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Fasting decreases hunger which makes it more effective than dieting

Ghrelin is the so-called hunger hormone, first purified from rat stomach in 1999 and subsequently cloned. It binds to growth hormone (GH) secretagogue receptor, which strongly stimulates GH. So, eating, by itself does not makes you gain lean tissue (like muscle and bone), despite what all the makers of supplements like whey protein and creatine claim. Rather, hunger may be a strong growth stimulus.

Nothing turns off Growth Hormone like eating and you need GH to grow functional tissue. Of course, food provides the nutrients needed to grow, so in fact, you need both feeding and fasting cycles to properly grow. Not all feeding, and not all fasting. Life lies in the balance of the two. The cycle of life is feast and fast. But in today’s world, many people would have you believe that fasting is detrimental to your health, and that you should eat all the time.

The biggest worry about fasting is dealing with hunger. People assume that hunger will get worse and worse until you cannot help yourself and start an IV donut slurry in your garage. Oooh… donuts…. Ghrelin, the hunger hormone, increases appetite and weight gain. It also antagonizes the effect of leptin (in rats at least). Leptin is a hormone produced by fat cells which turns off appetite and makes us stop eating.

Ghrelin turns on appetite. So, if you want to lose weight on a long term basis, you need to tune down ghrelin. If you don’t eat (fast), don’t you get hungrier and hungrier, ghrelin goes up and up and you’ll just gain weight?

Well, no. As we discussed last week, eating all the time sounds like it will turn off hunger and ghrelin. But that’s far too simplistic. Surprisingly, the answer to turning down ghrelin (and hunger) is the opposite — fasting.

Let’s look at this study “Spontaneous 24-h ghrelin secretion pattern in fasting subjects“. Patients undertook a 33 hour fast, and ghrelin was measured every 20 minutes. Here’s what ghrelin levels look like over time.

There are several things to notice. First, ghrelin levels are lowest at approximately 8:00 – 9:00 in the morning.

Circadian rhythm studies consistently find that hunger is lowest first thing in the morning, also generally the longest period of the day where you have not eaten.

This reinforces the fact that hunger is not simply a function of ‘not having eaten in a while’. At 9:00, you have not eaten for about 14 hours, yet you are the least hungry. Eating, remember, does not necessarily make you less hungry.

Next, notice that there are 3 distinct peaks corresponding to lunch, dinner and the next day’s breakfast. BUT IT DOES NOT CONTINUALLY INCREASE. After the initial wave of hunger, it recedes, even if you don’t eat.

Ghrelin shows a “spontaneous decrease after approximately 2 h without food consumption”. This correlates perfectly to our clinical experience in the Intensive Dietary Management Program that ‘hunger comes in waves’.

If you simply ignore it, it will disappear. Think of a time that you were too busy and worked right through lunch. At about 1:00 you were hungry, but if you just drank some tea, by 3:00 pm, you were no longer hungry. I often feel the same level of hunger whether I ate lunch or not — exactly what the ghrelin studies show. Ride the waves — it passes.

Also note that ghrelin does have a learned component since all these subjects were used to eating 3 meals per day. It is not merely by coincidence that these peaks of ghrelin happen. This is similar to the ‘cephalic phase’ of insulin secretion that we’ve discussed previously.

There was one other big finding of this study. Look at the average ghrelin levels over 24 hours. Over the entire day of fasting, ghrelin stays stable! In other words, eating nothing over 33 hours made you no more or less hungry than when you started! Whether you ate or did not eat, your hunger level stayed the same.

Eating more sometimes makes you more hungry, not less. In the same vein, eating less can actually make you less hungry. That’s terrific, because if you are less hungry, you will eat less, and are more likely to lose weight.

So what happens over multiple days of fasting? This study looked at the question specifically. 33 subjects had their ghrelin measured over 84 hours of fasting and they divided the results by men and women, as well as obese and lean.

There were no significant differences between the lean and obese subjects, so I won’t dwell on that further. Once again, there were distinct circadian variations.

Over 3 days of fasting, ghrelin gradually DECREASED. This means that patients were far LESS hungry despite not having eaten for the past 3 days. This jives perfectly with our clinical experience with hundreds of patients undergoing extended fasting in our IDM program.

Everybody expects to be ravenously hungry after fasting multiple days, but actually find that their hunger completely disappears.

They always come in saying ‘I can’t eat much anymore. I get full so fast. I think my stomach shrank’. That’s PERFECT, because if you are eating less but getting more full, you are going to be more likely to keep the weight off.

 

Notice, also the difference between men and women. There’s only a mild effect for men. But the women show a huge decrease in ghrelin. Again, this addresses one of the major worries that women are not able to fast.

Actually, women would be expected to have more benefit from fasting because their hunger can be expected to decrease better than men. Notice, too, how much higher women’s ghrelin level reaches.

I suspect this correlates to the clinical observation that many more women are ‘addicted’ to certain foods eg. chocoholics. Sugar addicts. etc.

So many women have remarked how a longer fast seemed to completely turn off those cravings. This is the physiologic reason why.

A few other notes about the hormonal changes of fasting. Notice that cortisol does go up during fasting.

Yes, fasting is a stress to the body and cortisol acts as general activator as well as trying to move glucose out of storage and into the blood. So, if too much cortisol is your problem, then fasting may not be right for you.

Insulin also goes down, which is what we expect. Growth hormone, as we’ve previously noted, goes up during fasting. This helps to maintain lean muscle tissue and to rebuild lost protein when you start to eat again.

An interesting study of food cravings found exactly what we have been discussing. When patients were put on low calorie diet (1200) versus very low calorie (500) diets, food cravings didn’t change much on the former, but virtually disappeared on the latter. Yes. By eating almost nothing, food cravings did not get worse, they got much, much better.
This effect on food cravings is true for all food, since all foods are restricted. So cravings for sweets, carbs and high fat foods are all reduced.
This is very important in the fight to lose weight. Controlling hunger by eating little bits at a time simply does not work.

During intermittent and extended fasting, ghrelin, the main hormonal mediator of hunger does not increase to unmanageable levels. Rather it decreases — which is exactly what we are looking for.

We want to eat less, but be more full. Fasting, unlike caloric restriction diets is the way to do that.

Don’t believe the LIES about Garcinia Cambogia

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Since the late 1990’s Garcinia Cambogia has been included in various weight loss products, but exploded in popularity in 2012 when Dr Julie Chen talked about it on the Dr Oz TV show.

Unfortunately, there is an avalanche of faulty information about Garcinia Cambogia on the web that we attempt to clean up below.

WHAT THE RESEARCH SAYS

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Several studies on rats have demonstrated significant weight loss, belly fat reduction, and lowered blood glucose levels (456).

We looked at all the randomized, double-blind clinical studies on humans. Some we excluded were either too short (2 weeks), used too small a dose, or had other flaws such as a low fat, high carb diet which researchers believe had a negative impact on the results.


This chart shows the results from the most relevant clinical studies on Garcinia Cambogia, encompassing 307 participants (7,8,9,10).

All of these were Double Blind,Randomized Controlled Trials, with subjects given Garcinia Cambogia or Placebo over 8-12 weeks.

The average for these 4 studies was 4.1 pounds lost vs 1.7 for those taking Placebo.

It should be noted that studies #3 and 4 used the highest dosages of 2800 mg daily, and showed the greatest amount of weight loss compared to placebo.

Studies #1 and 2 showed the least amount of weight loss benefit, and also used the lowest amount of Garcinia Cambogia, at 1200 mg per day.

[box]Conclusion: The average for the 4 relevant clinical studies on humans showed weight loss of 3 pounds more than placebo. Studies that used higher doses of HCA recorded more weight loss. [/box]

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What brand of Garcinia Cambogia should you Buy

You really need to read the label. Many brands are pushing inferior products. If they don’t show you the label, chances are they are trying to push you some crappy, useless stuff and don’t want you to realize it until you take it and don’t get any results.

Always Look for the HCA!

HCA, or hydroxycitric acid, is the active ingredient. You need to make sure it has at LEAST 60% HCA in it – Higher is better. Also check to make sure they don’t use a lot of added ingredients – especially if they’re hard to read, nearly impossible to pronounce ingredients.
wwrecommend
We’ve looked at all the leading brands sold on Amazon. There are several that are good, and dozens that are garbage.
The best quality we found that also has a good price is NewLifeBotanical’s Garcinia Cambogia.
If you find it more convenient, you can get it on Amazon

[product_category category=”garcinia-cambogia-2″ columns=”3″ per_page=”6″ orderby=”menu_id” order=”desc”]

Reasons why we recommend it:

  • Has 90% HCA!
  • No filler ingredients – all natural only
  • 600mg per capsule
  • Has been PROVEN to be effective
  • Has NO additives, fillers and other low-quality ingredients

 

PHARMACEUTICAL COMPANIES HATE GARCINIA CAMBOGIA

According to this article in Washington Post, it cost between $800 million and $2.6 BILLION to bring a new prescription drug to market.

Once they start clinical trials, the pharmaceutical company only has 20 years of patent protection to recoup that cost, so they have to charge exorbitant prices to make that back and pay their shareholders a good return on their investment.

Of course they don’t want potential customers to think a natural product that cost a tiny fraction of what they charge can be effective at all.

Hence pharmaceutical manufacturers often fund research studies they hope will cast the competition in a bad light. A few million dollars to fund a study on a competitor is nothing compared to the billions it cost to develop a drug.

For example, this meta-review that examines existing clinical studies on Garcinia Cambogia is funded by GlaxoSmithKline, the manufacturer of the prescription weight loss pill Orlistat, marketed under the name Alli.

For reference, Alli cost $60 for 120 capsules! The literature claims it can block 25% of the fat you eat from being absorbed.

Not surprisingly, the research they pay for often finds mixed results, with some studies showing positive effects for Garcinia Cambogia and some not.

The academic editor for that meta review was also the lead author for a few of the studies that found Garcinia to be ineffective. He also was the lead author for several studies that showed positive results for Orlistat (1,2,3).

[box] Conclusion: Big Pharma spends hundreds of millions of $$$ funding research to cast doubt on the effectiveness of natural weight loss products like Garcinia Cambogia.
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HOW DOES IT HELP WITH WEIGHT LOSS?

Garcinia Cambogia is somewhat unique in that there are 2 pathways the HCA utilizes to help with weight loss

1. It May Help Reduce Hunger

too hungry

Studies with rats have shown those given Garcinia Cambogia tend to eat less than those in the control group(11, 12).

How it works isn’t fully known, but those studies seem to indicate it increases levels of serotonin in the brain. (13, 14).

Likewise, some clinical studies with humans has shown it tends promote feeling of satiety (fullness), so you eat less. (15, 16, 17, 18, 19).

Serotonin is the “feel good” hormone that promotes feelings of satisfaction and is well known to be an appetite suppressant. (20).

Those studies are in contrast to some others that found no benefit for suppressing appetite vs those given placebo. (21, 22, 23, 24). Its not clear why studies have shown such a difference and more study is needed.

Conclusion: Some studies have shown garcinia cambogia increases serotonin to suppress appetite, but there have been other studies that could not replicate this effect.

2. It May Block Fat Production and Reduce Belly Fat

The effect HCA has on fatty acids in the bloodstream is the most important factor in its ability to aid weight loss.

Human and animal studies has shown HCA helps lower levels of triglycerides in the blood, reducing the oxidative stress throughout the body. (25, 26, 27, 28, 28).

It is even more attractive as a weight loss aid as it helps reduce belly. (29).

Another study gave moderately obese individuals 2,800 mg of garcinia cambogia daily for eight weeks (30).
After completion, participants had dramatically lower markers of metabolic disease such as:

  • 6.3% LOWER Total cholesterol levels
  • 12.3% LOWER LDL (the “bad”) cholesterol levels
  • 10.7% HIGHER HDL (the “good”) cholesterol levels
  • 8.6% LOWER Blood triglycerides

This is due to the inhibition of the enzyme citrate lyase, which signals the production of fat in the body (32, 33, 34, 35, 36).

By inhibiting citrate lyase, garcinia cambogia is thought to slow down or block fat production in the body. This may reduce blood fats and lower the risk of weight gain, two major disease risk factors (37).

Conclusion: Garcinia cambogia blocks the production of new fats in the body, and has been shown to lower cholesterol levels and blood triglycerides in overweight people.

OTHER HEALTH BENEFITS

Animal and test-tube studies suggest that garcinia cambogia may also have some anti-diabetic effects, including (38, 39, 40):

  • Decreasing insulin levels
  • Decreasing leptin levels
  • Reducing inflammation
  • Improving blood sugar control
  • Increasing insulin sensitivity

Garcinia cambogia may also have benefits for the digestive system. Animal studies have suggested it helps protect against stomach ulcers and reduce damage to the inner lining of the digestive tract (41, 42).

However, these effects need to be studied further before firm conclusions can be drawn.

Conclusion:Garcinia Cambogia may help lower blood sugar levels and increase insulin sensitivity to combat diabetes

 

SIDE EFFECTS

Generally Recognized as Safe (GRAS)
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Garcinia Cambogia is recognized as GRAS by the FDA, meaning it has “been adequately shown to be safe under the conditions of its intended use”.

There have been several studies to test the effectiveness of these products and in these controlled quantities there were no significant side effects.

This meta-analysis examined all published research on Garcinia Cambogia, and found garcinia to be free from any major side effects when taken at dosages up to 2800 mgs per day (with 60% HCA)

Screenshot 2016-03-28 12.30.09

WHO SHOULD NOT TAKE GARCINIA CAMBOGIA

garcinia warning

It  IS safe for most people. But there are a few cases where you wouldn’t want to take it:

  • Pregnant
  • Breastfeeding
  • Alzheimers or dementia

Garcinia Cambogia boosts serotonin levels in the brain (which triggers the satisfied, full feeling that helps suppress appetite).

For this reason, it is not advised for patients with neurological disorders such as Alzheimers, Parkinsons, or other forms of dementia.

DOSAGE AND WHEN TO TAKE IT

Dr Harry Preuss is  a researcher and pathologist at Georgetown University past president of the American College of Nutrition who has led 2 of the studies on HCA that showed the best results (43,44)  He says:

“YOU HAVE TO TAKE THE RIGHT DOSE OF THE RIGHT PRODUCT, AND YOU HAVE TO TAKE IT PROPERLY.”

The 4 studies that were included in the meta-analysis referenced above noted that 1 to 2.8 grams daily were used in testing, and that 2.8 grams seemed more effective (45)

Different studies that have been performed to focus on side effects found no major side effects at dosages up to 2.8 grams daily (46).

Dosage recommendations from those studies are:

  • 500 to 1000mg capsules
  • 70% or higher HCA
  • 3 times a day
  • 30-60 minutes before meals
  • taken with 8 ounces of water

70% HCA means that the manufacturer has standardized the extract to be 70% Hydroxycitric Acid by volume.

50-60% was the highest purity commercially available until recently, so has been the standard used for testing.

The higher percentage provides more total HCA per capsule, but is not more effective otherwise.

In other words, the higher HCA % is not “better”,  you just need less of it.

For proper dosage, you should lower the quantity if you use a product with HCA % higher than the 60% used in studies.

For example, the maximum recommended dosage of 3 grams per day of a 60% HCA product would yield 1800 mg of pure HCA – the same as 2 grams of 90% HCA.

[box]**** DAILY MAXIMUM RECOMMENDED DOSAGE ****

3,000 mg  x 60% HCA =   1800mg  pure HCA
2,000 mg  x 90% HCA = 1800mg  pure HCA[/box]

BUYING ON AMAZON – BEWARE THE SCAMS

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With any popular diet product, there are lots of scams that sell crappy product at ridiculous prices, and some that disappear with your money.

You might want to review some guidelines by the FTC in spotting the crooks.

It is becoming more common now with Garcinia, so beware, and read some of our reviews of brands like Ultra, Extreme, Purely Inspired, Miracle, Whole Body, Natural, and Pure Garcinia Cambogia.

Amazon is super convenient, and great at making sure you get what you order. But they don’t do anything to ensure the quality of a product.

Any brand that just popped up yesterday and will be gone tomorrow is NOT concerned with quality.

DR OZ WARNS ABOUT FAKE PRODUCTS

There are now dozens of new “Brands” of Garcinia Cambogia sold on Amazon that just make up a name and throw a label on some garbage product. And, they LIE about what is in the bottle!

The following quote is directly from the Dr Oz website where they warn about such deceptive marketing.

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This doesn’t mean all products sold on Amazon are bad. It just warns that products sold ONLY on Amazon are a much higher risk for being very poor quality.

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Conclusion: Beware any Brand or Product that is sold exclusively online and not in a brick in mortar store. Those that exist only on Amazon and do not even have a website of their own are very likely to sell a very poor quality product.
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WHAT WE RECOMMEND

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CONCLUSION

For Weight Loss, we are convinced that:

The Ketogenic Diet(47,48), preferably combined with Intermittent Fasting is the most effective way to lose weight.

High Intensity Interval Training (HIIT) can greatly increase your metabolism to make weight loss easier and faster.

As for Garcinia Cambogia, the evidence shows that:

  • Garcinia Cambogia is NOT A MAGIC PILL that will melt the fat off
  • Garcinia Cambogia CAN HELP you lose a few more pounds a month

Low-Fat Foods Are Higher in Sugar

Many people believe that low-fat foods are generally higher in added sugar than the original full-fat versions.

Although this is highly plausible, it has never been scientifically confirmed.

For this reason, a group of Californian scientists decided to systematically compare the sugar content of several common full-fat foods with their lower-fat alternatives.

Below is a detailed summary of their findings, recently published in Nutrition & Diabetes.

Background

In the late 70’s, public health authorities started recommending reduced fat consumption.

In response to increased consumer demands, food producers started offering low-fat or fat-free versions of foods.

However, this may not have been a step in a healthier direction. First, fat may not be as unhealthy as it was made out to be.

Second, food producers may have intentionally increased the sugar content of some processed food products to make up for the lack of tastiness caused by reducing their fat content.

This may have adversely affected people’s health, since sugar promotes obesity and chronic disease (12).

Article Reviewed

This article presents the results of a systematic comparison of the sugar content of full-fat and reduced-fat versions of common foods.

A systematic comparison of sugar content in low-fat vs regular versions of food.

Study Design

The purpose of this simple study was to compare the sugar content of common foods and their fat-reduced versions.

The selection of foods was based on a list of foods recommended by the US National Heart, Lung, and Blood Institute.

This was a list of high-calorie, high-fat foods along with “healthier”, low-fat alternatives. The nutrient content of these foods was obtained from the USDA Nutrient Database.

Finally, the researchers used statistics to compare the sugar content in 100 grams of the regular, low-fat and non-fat versions of the selected foods.

Bottom Line: This study compared the sugar content of the regular, low-fat and non-fat versions of several common foods.

Finding: Lower-Fat Means Higher-Sugar

The study found that low-fat versions of foods were, on average, higher in sugar.

Additionally, the study showed a significant difference in the sugar content of the regular and low/non-fat versions of the following food groups:

  • Dairy products.
  • Meat, fish and poultry.
  • Baked goods, including snacks and sweets.
  • Fats, oils and salad dressings.

The difference was usually small, as shown in the chart below. It shows the median sugar content (g) of the regular, low-fat (“light”) and non-fat versions of foods within the four food groups.

Bottom Line: The study showed that full-fat versions of foods are lower in sugar than their low-fat or fat-free alternatives.

Limitations

The results of this study were presented as a “short communication”, including minimal details on the study’s methods and results.

For this reason, it is difficult to assess the study’s limitations. However, a few potential shortfalls should be mentioned.

First, it compared the sugar content of a limited number of foods.

Second, when you remove fat from a food product, such as milk, the relative proportions of protein, carbs and sugar increase.

This may create a statistically significant difference in the sugar content of full-fat and lower-fat foods, even if they do not contain any added sugar.

Third, the USDA Nutrient Database does not distinguish between added sugar and sugar that’s naturally present in whole foods.

The researchers did not address these potential limitations.

Bottom Line: This study had a few potential limitations. For example, it did not distinguish between added sugar and sugar that is naturally present in foods.

Summary and Real-Life Application

Gram for gram, there is no doubt that low-fat foods contain higher amounts of sugar than full-fat versions.

There are two possible reasons for this:

  1. The relative proportion of sugar increases when fat is removed.
  2. Food producers add more sugar to low-fat and fat-free products.

The present study does not distinguish between these two possibilities.

Whether people should chose full-fat or low-fat versions of foods depends entirely on their nutrient composition.

For example, choosing a low-fat food product may be good if it means that you are getting more protein without a large increase in sugar.

On the other hand, if it means that you’re getting a lot more sugar, then it is probably healthier to stick to the regular, full-fat version.

Alternate-Day Fasting Increases Fullness After Meals

Alternate-day fasting is a version of intermittent fasting, which is currently one of the world’s most popular weight loss trends.

Recently, a group of scientists examined the effects of 8-week alternate-day fasting on appetite ratings, appetite hormones and body weight.

Here is a detailed summary of their results.

Empty Orange Plate

Background

Alternate-day fasting (ADF) is a weight loss technique that has recently become popular (1).

One popular version of ADF restricts calories by 75% every second day, while allowing unrestricted eating in between.

Human trials have shown that this method may lead to 4–8% weight loss in just 2–3 months. Here is a summary of study results from over the years:

  • 2005: 16 non-obese men and women fasted every other day for 22 days and lost 2.5% of their initial body weight (2).
  • 2007: 9 overweight asthma patients consumed 20% of their calorie needs every second day for 8 weeks and lost 8% of their initial body weight (3).
  • 2009: 16 obese people consumed 25% of their calorie needs every second day for 8 weeks and lost 12.4 lbs (5.6 kg) (4).
  • 2013: 32 obese people fasted every other day for 8 weeks and lost 4.8% of their body weight on a high-fat diet (45% fat), but 4.2% on a low-fat diet (25% fat) (5).
  • 2013: 32 obese people fasted every other day for 12 weeks and lost 6.6 lbs (3 kg). When fasting and doing endurance exercise, they lost 13.2 lbs (6 kg) (6).
  • 2013: 15 overweight or obese women fasted every other day for 6 weeks and lost 7% of their initial body weight (7).

Additionally, giving in to hunger and cravings is the main reason why people fail to adhere to a diet (8).

This seems to be less common during ADF, though the reason is not clear (9).

Article Reviewed

This trial examined how ADF affects appetite ratings, appetite hormones and weight.

Changes in hunger and fullness in relation to gut peptides before and after 8 weeks of alternate day fasting.

Study Design

This trial examined the effects of 8-week ADF on subjective ratings of appetite, appetite hormones and body weight.

It should be noted that results from this study have been published before (10).

A total of 59 middle-aged, obese adults completed the trial, or 80% of those who initially started. 84% of the participants were women.

The study was divided into 3 periods:

  • Control period 1: For 2 weeks, the participants followed their habitual diets. Initial measurements took place during this period.
  • Alternate-day fasting: For 8 weeks, the participants fasted every second day.
  • Control period 2: Immediately after the ADF, participants followed their habitual diet for 2–3 days before final appetite measurements were taken.

Bottom Line: This trial examined how ADF affects appetite and body weight. The study included 59 people, and was divided into three periods.

Alternate-Day Fasting

For 8 weeks, the participants fasted every second day, with 75% calorie restriction. Conversely, on “feed days” they were allowed to eat whatever they wanted.

To improve compliance, all participants were provided with the food they were allowed to eat on fast days.

This food contained 60% of calories from carbs, 24% from fat and 16% from protein. Participants were allowed to consume unlimited amounts of calorie-free drinks.

Every week, the researchers measured body weight. Fat mass, lean mass and intra-abdominal fat were also measured using DXA.

Bottom Line: The participants consumed 25% of their calorie needs every other day for 8 weeks.

Appetite Assessment

Subjective ratings of appetite were assessed after a 12-hour fast, before and after a standardized meal.

The standardized meal consisted of a liquid meal, providing 440 calories. It was designed to have a similar macronutrient profile as a typical breakfast, or 60% of calories from carbs, 24% from fat and 16% from protein.

Fasting blood samples were taken before the meal. Blood was also drawn immediately after the meal, and at 30, 90 and 120 minutes afterwards.

The blood was analyzed for total ghrelin, peptide YY (PYY) and several other hormones. Immediately before each of the blood draws, the participants rated their appetite using a visual analog scale (VAS).

Bottom Line: Appetite hormones and subjective ratings of appetite were assessed before and after the 8 weeks of ADF.

Finding 1: Body Weight Decreased

During eight weeks of ADF, the participants lost 8.6 lbs (3.9 kg).

This weight loss was largely due to loss of fat — 4.9 lbs (2.2 kg) — but also lean mass (water and muscle) — 3.1 lbs (1.4 kg).

The chart below shows the changes in fat mass and lean mass.

Fat and Lean Mass Change

Bottom Line: Fasting every other day for 8 weeks led to 8.6 lbs (3.9 kg) weight loss.

Finding 2: Fullness After Meals Increased

Subjective ratings of fullness after the test meal were significantly higher after 8 weeks of ADF, as shown below.

Start and End Fullness

This increase in fullness was associated with higher levels of peptide YY, which is a hormone that reduces appetite after meals (1112).

Similar to fullness, PYY levels after meals increased after 8 weeks of ADF. The reason why ADF increased PYY levels and fullness is unclear.

Bottom Line: Post-meal fullness was greater after 8 weeks of ADF, compared to before.

Finding 3: Ratings of Hunger Remained Unchanged

Eight weeks of ADF did not change hunger ratings.

This is consistent with previous studies suggesting that hunger remains unchanged after 3–12 weeks of ADF (23913).

Conversely, studies on hunger after continuous calorie restriction indicate that compensatory increases in hunger are common (141516).

Taken together, these findings indicate that intermittent calorie restriction is easier to stick to than continuous dieting or fasting.

However, levels of the hunger hormone ghrelin were significantly higher after the test meal at the end of the trial, compared to its levels before the trial.

The reason for these findings is unknown.

Bottom Line: Despite the loss of weight, subjective ratings of hunger didn’t change. This indicates that ADF is easier to adhere to than dieting.

Limitations

This study had a few limitations.

First, meals were not standardized the day before the appetite measurements took place. Even though the tests were preceded by a 12-hour fast, the previous evening’s meal might have affected the findings.

Second, one of the authors, Krista Varady, wrote the book The Every Other Day Diet, creating a conflict of interest. None of the other authors reported competing interests.

Summary and Real-Life Application

ADF is an effective weight loss strategy, causing significant weight loss after 8 weeks. Yet despite the weight loss, hunger ratings after a standardized meal remained unchanged.

Additionally, when the ADF was over and the participants went back on their regular diets, subjective ratings of fullness were significantly higher after the standardized meal, compared to a similar meal before the fast.

These findings suggest that ADF is relatively easy to stick to. However, further studies need to examine its long-term effects.

Some People May Be Genetically Adapted to Vegetarian Diets

Scientists have hypothesized that people who follow plant-based diets for many generations are better adapted to vegan or vegetarian diets.

In other words, some populations may be better at getting the nutrients they need from these diets. Recently, a group of researchers tested this hypothesis.

Here is a summary of their results.

Background

Arachidonic acid is a long-chain, polyunsaturated omega-6 fat. It’s mainly found in animal-derived foods, such as meat, dairy and eggs.

Adequate amounts of arachidonic acid are necessary for normal body function. Yet when arachidonic acid is in short supply, the body can produce it from linoleic acid.

For this reason, vegans can get the arachidonic acid they need from linoleic acid, which is found in high amounts in many vegetable oils.

Although this conversion is usually inefficient, some people may be better at producing arachidonic acid from linoleic acid.

Article Reviewed

Researchers examined whether a variation of the FADS2 gene, which is involved in the conversion of linoleic acid to arachidonic acid, would result in improved levels.

They also tested the frequency of this gene in different populations.

Positive Selection on a Regulatory Insertion–Deletion Polymorphism in FADS2 Influences Apparent Endogenous Synthesis of Arachidonic Acid.

Study Design

The purpose of this study was to examine whether a variation of the FASDS2 gene resulted in higher arachidonic acid levels.

Additionally, the researchers wanted to find out if the proportion of people with this gene differed between human populations.

The researchers compared two groups of people:

  • Indians: 234 participants were from Pune, India. About 38% were vegetarian. In this area, people have been largely vegetarian for thousands of years.
  • North Americans: 311 participants were from the US and Canada. However, most of them came from Kansas.

The researchers also used reference data from the 1,000 Genomes Project. This allowed them to compare a greater number of different populations.

Additionally, the levels of arachidonic acid in red blood cells were analyzed in the 199 participants who came from Kansas.

Bottom Line: This study examined if a variation of the FADS2 gene led to higher levels of arachidonic acid, and if it was more common in traditionally vegetarian populations.

Finding: Some People Are Better at Producing Arachidonic Acid

This study showed some people have a variation of the FADS2 gene (rs66698963) that makes it easier for them to produce arachidonic acid from linoleic acid.

This implies that they are better adapted to a diet that’s very low in arachidonic acid, such as a vegan diet. Additionally, the study found that the percentage of people with this gene variation differed between populations.

Specifically, it was much higher in Indians, and other people in South Asia, compared to North Americans and Europeans. This can be seen in the chart below.

Pie Chart of Vegans

What’s more, the levels of arachidonic acid were, on average, 8% higher among those who had this gene variation, compared to those who didn’t.

Evolutionary tests also revealed that these population differences were unlikely due to chance. In other words, it appears they may be genetic adaptations reflecting traditional, ancestral diets.

Bottom Line: The study found that the gene variant led to higher circulating levels of arachidonic acid. It also showed that it was more common in India and south Asia, compared to North America and Europe.

What Are the Health Implications?

According to some estimates, humans evolved eating omega-6 and omega-3 fatty acids in the ratio 4:1 to 1:1 (1).

Today, vegetable oils rich in omega-6 linoleic acid are widely used in cooking and processed foods. These include corn, soybean, cottonseed and sunflower oils.

For this reason, the ratio of omega-6 to omega-3 in the Western diet may even reach above 10:1 (23).

Some scientists are concerned that a high omega-6 to omega-3 ratio may promote inflammation and increase the risk of heart disease, diabetes and cancer (234).

The authors of the current study speculated that individuals with the rs66698963 gene variation may be at a greater risk of developing inflammation-related, chronic disease when following a diet high in omega-6 linoleic acid and/or arachidonic acid.

For this reason, it is possible that people with this gene variant might be better off sticking to vegetarian diets that do not contain much arachidonic acid and are relatively low in linoleic acid.

Conversely, people without this gene variant should try to get some arachidonic acid from their diet. Strict vegan diets might not suit them.

These are speculations, however, and further studies are needed.

Bottom Line: The health implications of the findings are unclear. The authors speculated that people with the vegetarian gene variant may be better off limiting their intake of arachidonic acid and linoleic acid.

Limitations

This study did not seem to have many limitations, but the health relevance of the results is unclear.

Additionally, the levels of arachidonic acid were only measured in those participants who came from Kansas in the US, but not in the Indian population.

Summary and Real-Life Application

In short, this study showed that some people have a certain gene variant that makes them better at converting linoleic acid into arachidonic acid.

This seems to be an adaptation to plant-based diets that contain low levels of arachidonic acid.

Additionally, this gene variant is more common in India and Southeast Asia, compared to North America and Europe.

The health implications are unknown, but the authors speculated that people who have this variant should try to limit their linoleic acid and arachidonic acid intake.

Can Yogurt Help You Lose Weight? The Surprising Truth

Yogurt is a popular dairy product made by adding live bacteria to milk.

Without added sugar, it is generally considered to be very healthy. Some studies even link yogurt to a reduced risk of weight gain and obesity.

Recently, a team of scientist decided to do a thorough review of all the evidence on yogurt consumption and weight loss/gain.

This article presents a detailed summary of their findings.

Strawberry Yogurt and Berries

Background

Conventional yogurt is a type of fermented milk that contains cultures of bacteria, mainly Streptococcus thermophilus and Lactobacillus delbrueckii.

Probiotic yogurt contains added probiotic bacteria, such as Bifidobacterium lactis and Lactobacillus acidophilus. Yogurt must also contain lactic acid, a minimum of 2.7% milk protein and less than 15% milk fat.

Many studies have examined the effects of conventional yogurt on health, and reviews have concluded that yogurt may reduce the risk of type 2 diabetes (123).

However, until now, no reviews have examined how yogurt affects body weight.

Article Reviewed

This was a systematic review of studies on the association between conventional yogurt and weight management.

Is consuming yoghurt associated with weight management outcomes? Results from a systematic review.

Study Design

This review and meta-analysis examined the association between conventional yogurt and weight-related outcomes in healthy adults.

It was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines (4).

The researchers found 22 eligible studies, 13 observational studies, 6 randomized controlled trials and 1 controlled trial.

These studies examined the effects of yogurt in healthy, normal populations, but not in people with obesity or specific diseases.

Additionally, the researchers excluded studies investigating probiotic yogurt, kefir, kumis or yogurt with added vitamins, protein or fat.

Bottom Line: This systematic review and meta-analysis examined how eating conventional yogurt affects weight-related outcomes.

Finding 1: Eating Yogurt is Associated With Lower Body Weight

Observational studies show that eating yogurt is associated with lower body weight, body mass index (BMI), body fat and a smaller waist circumference.

However, observational studies cannot prove a cause-and-effect relationship.

It is highly likely that a high consumption of yogurt is associated with other healthy lifestyle factors that could influence body weight.

Bottom Line: Observational studies showed that eating yogurt was linked to lower body weight, BMI, body fat and a smaller waist circumference.

Finding 2: Eating Yogurt Might Reduce Weight

A total of 6 randomized controlled trials (RCTs) were included in this systematic review. Here are brief summaries of 5 of the selected studies.

  • Compared to the control, yogurt caused more weight loss, body fat reduction and reduction in waist circumference. It also helped retain lean body mass (5).
  • Yogurt did not reduce body fat, compared to the control groups (6).
  • Body weight, body mass index (BMI), waist circumference and body fat did not decrease more after consuming yogurt, compared to a placebo (7).
  • Eating yogurt did not lead to a greater reduction in body weight, BMI or body fat, compared to a placebo (8).
  • Yogurt caused a small, but statistically significant, increase in body weight (9).

However, this last study was not a weight loss trial and the participants were given one liter of several dairy products (9).

Also, it should be noted that only one of these studies showed that yogurt caused significant improvements to body weight and composition (5).

Yet when the results from several of these studies were combined in a meta-analysis, there was evidence that yogurt may have modest weight loss benefits.

Nevertheless, none of these trials could prove that the yogurt itself actually led to changes in body weight.

Bottom Line: Randomized controlled trials have provided mixed results, but together suggest that yogurt may cause modest weight loss.

How Might Yogurt Affect Weight?

The available evidence suggests that yogurt may promote a healthy body weight.

This could be due to a higher protein intake among people who eat a lot of yogurt.

Additionally, some yogurts contain live probiotic bacteria, which may promote weight loss. This is discussed in a previous research review.

However, this review focused on conventional yogurt, not probiotic yogurt.

Bottom Line: Why conventional yogurt would promote weight loss is unclear. However, studies suggest that probiotics may have health benefits.

Limitations

This systematic review was conducted according to strict standards and guidelines. In itself, it doesn’t appear to have many limitations.

The main limitations apply to the selected studies. Most of them were observational, but a few randomized controlled trials were also included.

These randomized controlled trials had several limitations. Some didn’t provide all relevant methodology, which made comparing and interpreting the results difficult.

Additionally, only one of the trials reported the type of bacterial strains in the yogurt used. For this reason, it can’t be ruled out that some of them included probiotics.

This also applied to the observational studies. The methods used to estimate yogurt consumption, such as food frequency questionnaires, are often inaccurate.

Finally, the authors concluded that none of the studies they used managed to separate the effects of yogurt, proving that yogurt consumption caused weight loss.

Bottom Line: The studies included in this systematic review had several limitations, and none could prove that eating yogurt led to weight loss.

Summary and Real-Life Application

In short, this systematic review indicates that eating conventional yogurt may have modest weight loss benefits.

However, the evidence was limited, and higher-quality studies are needed before a solid conclusion can be reached. Additionally, if you decide to eat more yogurt to lose weight, selecting sugar-free yogurt is recommended.

And although not the focus of this study, studies suggest that probiotic yogurt may have even greater health benefits.

Artificial Sweeteners in Pregnancy and Obesity in The Child

The use of artificial sweeteners has increased dramatically in recent decades.

At the same time, obesity rates have skyrocketed. However, the link between artificial sweetener use and obesity is controversial.

A new study was just done that examines the use of artificial sweeteners in pregnancy and the risk of obesity in child.

The findings were very interesting, and are outlined below.

Pregnant Woman With Candy Heart

Background

More than 30% of pregnant women may regularly consume artificially sweetened beverages (12).

Animal studies suggest that when unborn offspring are exposed to artificial sweeteners they are more likely to develop overweight or obesity after birth (34).

They also tend to have greater preferences for sweet foods, changed blood lipid profiles and increased insulin resistance (456).

However, until now, this association has never been examined in humans.

Article Reviewed

This study assessed the consumption of artificial sweeteners among pregnant mothers and examined its association with infant body mass index.

Association Between Artificially Sweetened Beverage Consumption During Pregnancy and Infant Body Mass Index

Study Design

This was an observational cohort study examining the link between maternal consumption of artificial sweeteners and infant obesity.

It included 2686 healthy, pregnant women from the Canadian Healthy Infant Longitudinal Development (CHILD) Study.

The dietary intake of these women was estimated using a food frequency questionnaire during the second or third trimester of pregnancy.

One year after birth, the researchers measured the body mass index (BMI) of their children.

Bottom Line: This observational study examined the association of artificial sweetener intake among pregnant mothers and infant body mass index at age one.

Finding: Maternal Consumption of Artificial Sweeteners Was Linked With an Increased Risk of Infant Overweight

More than a quarter of the women in this study consumed artificial sweeteners during pregnancy.

At one year of age, the children of those women who consumed a lot of artificial sweeteners during pregnancy had a higher body mass index (BMI) than those who consumed less.

Additionally, they were twice as likely to be overweight at age one, compared to those who weren’t exposed to artificial sweeteners while still in the womb.

Infants of women who consumed artificially sweetened beverages were 119% more likely to be overweight at 1 year, compared to women who consumed them less than once per month.

When the analysis was done separately for each gender, the researchers found that maternal intake of artificial sweeteners was only linked with body weight in boys. This is supported by a study in mice (5).

These associations remained significant even after adjusting for maternal BMI, diet quality, total calorie intake and other risk factors for obesity.

Bottom Line: The study showed that high intake of artificial sweeteners among pregnant women increased their child’s risk of becoming overweight or obese at age one. However, the association was only significant in boys.

Do Artificial Sweeteners Really Cause Weight Gain?

This was the first human study to suggest that maternal consumption of artificial sweeteners during pregnancy may increase the risk of weight gain and obesity in the infant.

A few observational in humans have also suggested that artificial sweeteners may increase the risk of weight gain and metabolic syndrome in adults (78).

However, these were all observational studies, meaning that they couldn’t demonstrate a cause-and-effect relationship.

Their results have also been inconsistent, with some studies suggesting that artificial sweeteners may reduce the risk of obesity (910).

Additionally, a recent meta-analysis of randomized controlled trials concluded that low-calorie sweeteners reduce calorie intake and body weight. This is discussed in a previous research review.

Bottom Line: Human studies haven’t proved that artificial sweeteners promote weight gain. Observational studies have provided inconsistent results.

How Might Artificial Sweeteners Cause Weight Gain?

Researchers have come up with several ideas of how eating artificial sweeteners could affect body weight in adults.

These include:

  • Changes in glucose metabolism (11).
  • Disruption of the gut microbiota (12).
  • Dysregulation of appetite control and calorie compensation (13).

Since artificial sweeteners have been detected in human breast milk, infants may be exposed to sweeteners consumed by their mothers (14).

Bottom Line: Several theories have been proposed to explain the possible effects of artificial sweeteners on body weight. These involve adverse changes in glucose metabolism or the gut microbiota.

Limitations

The main limitation of this study is its observational design.

Second, the study didn’t distinguish between different types of artificial sweeteners, and didn’t account for the amount found in solid foods.

Third, the researchers assessed the intake of artificial sweeteners using food frequency questionnaires (FFQ). Although they are generally good at differentiating between high and low consumers, FFQs are often inaccurate.

Additionally, the questionnaire used in the present study was not specifically validated for beverages.

Finally, infant overweight and obesity were estimated using BMI, which is an inaccurate measure of body fat.

Bottom Line: The study’s main limitation was its observational design. Measures of artificial sweetener intake and body fat were also inaccurate.

Summary and Real-Life Application

In short, this study suggests that high intake of artificial sweeteners among pregnant women may increase their children’s risk of excessive weight gain and obesity.

However, since the study had an observational design, it couldn’t prove that artificial sweeteners were responsible for the association.

For this reason, the role of artificial sweeteners in infant weight gain and obesity are still unclear. Randomized controlled trials are needed before any hard conclusions can be reached.

Fatty Acids Produced by Gut Bacteria Reduce Appetite

The most important health function of prebiotic fiber is to increase the formation of short-chain fatty acids (SCFAs) in the colon.

Not only do these fatty acids benefit colon health, but they also play a role in regulating appetite.

Recently, a team of researchers examined the effects of elevated propionate, which is one of the most common SCFAs, on calorie intake and brain signals involved with food reward-driven eating behavior.

Today’s review provides a detailed summary of their findings.

Young-Woman-Disgusted-By-Doughnuts

Background

Fiber is a key component of a healthy diet.

This especially applies to prebiotic fiber, which sustains the beneficial bacteria living in your digestive system.

When reaching the colon, prebiotic fiber is fermented by intestinal bacteria, producing short-chain fatty acids (SCFAs), mainly acetate, butyrate and propionate (1).

Growing evidence indicates that SCFAs produced by bacteria in the colon may affect appetite regulation in the brain (234).

One study in rodents showed that elevated amounts of acetate in the blood suppressed appetite by affecting brain function (4).

Another human study found that increasing the formation of propionate in the colon by supplementing with inulin-propionate ester was associated with a reduced food intake and protected against weight gain (5).

However, until now, no studies have examined the potential effects of colon-derived SCFAs on the human brain.

Article Reviewed

A team of researchers examined the effects of elevated short-chain fatty acid formation in the colon on reward-driven eating behavior in humans.

Increased colonic propionate reduces anticipatory reward responses in the human striatum to high-energy foods.

Study Design

This randomized, crossover trial examined the effects of increasing propionate formation in the colon on eating behavior.

A total of 20 healthy men, aged 18 to 65, participated in the study. Their body mass indexes ranged from 20 to 35.

They were assigned to receive two supplements in a random order:

  • Inulin: A soluble fiber that promotes the formation of SCFAs (acetate, butyrate and propionate) in the colon.
  • Inulin-propionate ester (IPE): Previous studies suggest that IPE provides similar amounts of acetate and butyrate as inulin but higher amounts of propionate (5).

After an overnight fast, the supplements were taken with breakfast when the participants visited the lab. The two lab visits were separated by at least 6 days.

The breakfast consisted of a standard chocolate milk shake and snack bar with 10 grams of either IPE (treatment) or inulin (control).

During each visit, the researchers measured the following:

  • Brain activity: 5 hours after breakfast the researchers measured brain activity using functional magnetic resonance imaging (fMRI) while the participants looked at pictures of low- and high-calorie foods.
  • Food appeal: While the participants were looking at the food images, they were asked to rate how appealing they found each of the foods, on a scale of 1 to 5.
  • Blood values: Blood samples were collected to measure circulating levels of insulin, glucose and two appetite-suppressing hormones: glucagon-like peptide 1 (GLP-1) and peptide YY (PYY).
  • Self-rated appetite: The participants were asked to rate their appetite and mood using visual analog scale questionnaires.
  • Breath hydrogen: The concentration of breath hydrogen was measured to assess the level of fermentation in the colon.
  • Food intake: At the end of each lab visit, the participants’ food intake was assessed by serving them a large meal consisting of a savory tomato and mozzarella pasta bake.

Bottom Line: This was a randomized, controlled trial examining the effects of elevated colonic propionate formation on calorie intake, appetite and food reward-related brain activity.

Finding 1: Colonic Propionate Reduced Food Intake

Supplementing with inulin-propionate ester (IPE) reduced food intake at an experimental meal by 9.5%, compared to supplementing with inulin.

These results are shown in the chart below:

Calories-Eaten-Inulin-And-IPE

The findings are supported by one previous human study showing that supplementing with IPE reduced food intake significantly (5).

The researchers concluded that these differences were likely due to elevated levels of propionate in the colon after the IPE supplement.

Changes in levels of insulin, glucose and the appetite-suppressing hormones GLP-1 and peptide YY were not significantly different between supplements, suggesting that other mechanisms may be responsible.

Bottom Line: Supplementing with inulin-propionate ester (IPE), which increases propionate levels in the colon, reduced calorie intake at an experimental meal, compared to supplementing with inulin.

Finding 2: Colonic Propionate Suppressed Reward Signals in the Brain

The researchers measured brain activity – the blood oxygen level–dependent (BOLD) signal – in brain regions that have previously been associated with food reward processing (6).

Supplementing with IPE suppressed food reward-related brain signals when the participants looked at images of food more than supplementing with inulin did.

Suppression of these brain signals was detected in two brain regions — the nucleus accumbens and caudate. It was greater when the participants looked at images of high-calorie foods, compared to low-calorie foods.

In fact, brain signals in the caudate were only suppressed by images of high-calorie foods, but not low-calorie foods.

The findings are presented in the chart below.

BOLD-Signal-In-Caudate

These results indicate that propionate suppressed food intake by affecting reward-driven eating behavior, although the researchers didn’t find any significant association between changes in brain signals and food intake.

Reduced BOLD signals have previously been linked to suppressed appetite and reduced appeal of high-calorie foods (78910).

However, this is the first study to suggest that propionate may affect these signals in humans.

Bottom Line: Supplementing with IPE suppressed brain activity in brain regions involved with food reward processing.

Finding 3: Colonic Propionate Made High-Calorie Foods Less Appealing

After the participants supplemented with IPE, they found high-calorie foods less appealing, according to ratings of food images.

It also took them longer to rate the images, which may indicate reduced appetite (1112).

However, self-rated appetite, as evaluated by visual analog scale questionnaires, was not significantly different between supplements.

Bottom Line: Supplementing with IPE made images of high-calorie foods less appealing, compared to supplementing with inulin.

Finding 4: Prebiotic Fiber Increased Fermentation in the Colon

Hydrogen gas is a by-product of fiber or carb fermentation in the colon. A large proportion of it is absorbed into your blood and released into your breath.

Since there are no other major sources of hydrogen in the human body, breath hydrogen levels are used to assess how much fermentation is taking place in the colon (13).

In the present study, breath hydrogen levels had increased significantly 3.5 hours after taking the supplements and stayed high until the end of the study visit.

Supplementing with inulin led to significantly greater breath hydrogen levels than IPE. This is because inulin contains higher amounts of fermentable fiber, or 10 grams, compared to 7.3 grams in the IPE supplement.

Circulating levels of butyrate also increased after supplementing with inulin and IPE, but the increase was not significantly different between supplements.

Bottom Line: Both supplements led to increased fiber fermentation in the colon, according to hydrogen breath tests.

Limitations

The study’s design appears excellent. However, there are a few limitations to the interpretation of its findings.

First, all of the participants were men, and none of them severely obese. The findings might not apply to women or severely obese people and need to be confirmed in these groups.

Second, the study examined the appetite and brain responses after a single dose of inulin or IPE. The long-term effects of these supplements on brain function need to be investigated.

Summary and Real-Life Application

The study showed that increased colonic formation of short-chain fatty acids (SCFAs), specifically propionate, may temporarily reduce calorie intake and the appeal of high-calorie foods.

This is supported by previous studies in both humans and animals, but this is the first study to show that propionate affects brain regions involved with food reward-driven behavior in humans.

Simply put, prebiotic fiber may play an important role in appetite regulation through its effects on SCFA formation in the colon.

Thriftiness: Another Piece of the Obesity Puzzle

Not everyone is equal when it comes to losing weight.

Multiple factors determine whether people are successful or not. Growing evidence suggests that one of them is thriftiness.

Recently, a group of researchers examined the association of thriftiness with body fat and body temperature.

Today’s research review provides a detailed summary of their findings.

Obese-Man-Struggling-To-Button-Pants

Background

Calorie expenditure is the rate at which you burn calories.

Previous studies suggest that a “slow metabolism” or low resting calorie expenditure is not the underlying cause of obesity in most people.

In fact, obese people may burn more calories at rest, compared to normal-weight people, as we discussed previously.

Yet, growing evidence shows that other aspects of calorie expenditure may explain why some people have a greater tendency to gain weight over time.

In fact, people’s physiological response to calorie deficit or overfeeding significantly varies between individuals (1234).

Some people are better adapted at preserving calories during periods of calorie deficit or malnutrition. These people are of the “thrifty phenotype.”

Most studies define thrifty individuals as having a greater decrease in calorie expenditure during fasting, compared to others (1).

This means that it’s more difficult for them to lose weight through dieting or fasting. One study showed that thrifty individuals lost less weight during a weight loss program (5).

It’s still unclear what causes people to become thrifty. Genetics may play a large role, but physical fitness or previous weight loss attempts could also be involved (67).

Article Reviewed

A team of scientists examined whether the decrease in calorie expenditure while fasting was associated with fat mass and body temperature.

Lower core body temperature and greater body fat are components of a human thrifty phenotype.

Study Design

This observational study examined whether changes in calorie expenditure in response to fasting were associated with body fat and body temperature.

The study was based on the results of two studies conducted at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) in Phoenix, Arizona.

Data from 77 men and women who participated in the studies was included in the final analyses. Their body mass index ranged from 17.8 to 50.

The researchers examined how calorie expenditure changed during three 24-hour periods — weight maintenance, overeating and fasting — during which the participants spent their time at the research unit.

During the 24-hours of weight maintenance and overeating the participants followed a standard diet.

The diet consisted of 4 meals (breakfast, lunch, an afternoon snack and dinner) and provided 50% of calories from carbs, 30% from fat and 20% from protein.

While the participants stayed at the research unit, the researchers measured the following:

  • Body weight: Each morning, the participants’ body weight was measured shortly after they woke up.
  • Body composition: The participants’ body composition was measured using dual-energy X-ray absorptiometry (DEXA). The measurements included percent body fat, fat mass, abdominal fat and fat-free mass.
  • Calorie expenditure: For 24 hours, starting 30 minutes after the participants finished breakfast, their calorie expenditure was assessed using a whole-room indirect calorimeter.
  • Core body temperature: Body temperature was measured continuously using small sensors equipped with transmitters. The participants swallowed the sensors shortly after they woke up.

Bottom Line: This was an observational study examining how the response of calorie expenditure to fasting (starvation response) was associated with body fat and body temperature.

Finding 1: Fasting Decreased Calorie Expenditure

The study showed that calorie expenditure decreased by 8%, on average, during fasting.

This is a natural response that reduces the risk of starvation during periods of food shortage, also known as starvation response, starvation mode, metabolic adaptation or adaptive thermogenesis (8).

One study suggested that the starvation response may in some cases persist over a few years, as discussed in our previous research review (9).

Bottom Line: Fasting for 24 hours significantly decreased calorie expenditure. This effect is known as the starvation response or adaptive thermogenesis.

Finding 2: Overeating Increased Calorie Expenditure

On average, overeating caused a 9.7% increase in calorie expenditure.

This effect is known as diet-induced thermogenesis or the thermic effect of food (TEF).

Previous studies indicate that TEF is influenced by various factors. For example, high-protein meals cause a greater TEF, compared to high-carb meals, and it appears to be stronger early in the day.

Bottom Line: Overeating for 24 hours caused a significant increase in calorie expenditure. This phenomenon is known as the thermic effect of food.

Finding 3: Some Individuals Had a Thrifty Phenotype

Not everyone responded to calorie deficit or excess in the same way. In fact, the response varied significantly between individuals.

Based on this response, the researchers divided the participants into two categories: thrifty and spendthrift individuals.

Specifically, thrifty individuals were below the median for the 24-hour response of calorie expenditure to fasting, whereas spendthrift individuals were above it (5).

The chart below shows the average differences in the responses of calorie expenditure to fasting and overeating.

Change-In-Calorie-Expenditure-Fasting-vs-Eating

Bottom Line: The researchers divided the participants into two categories – thrifty and spendthrift – depending on how their calorie expenditure changed in response to 24-hour fasting.

Finding 4: Thrifty Individuals Had Lower Body Temperature

The analyses of body temperature were limited to men, since body temperature may fluctuate during the menstrual cycle in women.

Thrifty individuals had a significantly lower core body temperature while fasting, overfeeding and during weight maintenance.

On average, thrifty men had a 0.29 °F lower core body temperature, compared to spendthrift men, as shown in the chart below.

Combined-Avg-Temp-Thrifty-Vs-Spendthrift-F-aligned

Body temperature and starvation response were significantly associated. Specifically, a 0.18 °F drop in core body temperature was linked to a 1.4% greater decrease in calorie expenditure during fasting.

A few previous observational studies have found that obese individuals have a lower body temperature, compared to normal-weight people, but not all studies agree (1011121314).

Bottom Line: Thrifty individuals had a lower body temperature, compared to spendthrift individuals.

Finding 5: Thrifty Individuals Had More Body Fat

Those who were categorized as thrifty had significantly greater total fat mass and abdominal fat, compared to those who were spendthrift.

On average, thrifty individuals had 17.7 lb more fat mass and 4.8 lb more abdominal fat, compared to spendthrift individuals. These findings are presented in the chart below.

Body-Fat-Thrify-Vs-Spendthrift

Similar results were obtained when the analyses were limited to men.

A greater decrease in calorie expenditure was also associated with greater total fat mass and abdominal fat. This association remained significant after taking age, gender, race and ambient temperature into account.

These results suggest that thrifty individuals have a greater tendency to gain weight, compared to their spendthrift counterparts.

They may also have greater difficulty losing weight while dieting. This is supported by one previous trial showing that thrifty, obese individuals were less successful at losing weight during a 6-week weight loss program that reduced calories by 50% (5).

Bottom Line: Thrifty individuals had lower total body fat and abdominal fat, compared to spendthrift individuals.

Limitations

The main limitation of the study was its observational design.

Although the results are valid, they do not allow any conclusions about causality.

For example, it is unknown whether thriftiness leads to obesity, or if obesity makes people thrifty. However, previous studies support the former possibility (515).

Summary and Real-Life Application

In short, this study confirms that some obese people are better at conserving calories than others.

The authors labeled them as “thrifty.” Thrifty individuals tended to have greater total fat mass, abdominal fat and lower body temperature, compared to those who were “spendthrift.”

What’s more, the starvation response of thrifty individuals was stronger, and the thermic effect of food was weaker.

Although these findings have limited real-life application, they show that not everyone is equal when it comes to losing weight.

Protein and Exercise May Prevent Muscle Loss While Dieting

Dieting often results in the loss of both fat and muscle mass.

Strength exercises and protein can help prevent the loss of muscle mass, yet studies disagree on how much you need.

A recent study examined these effects. Below is a detailed summary of their results, published in the American Journal of Clinical Nutrition.

Background

When you are on a calorie-reduced diet, loss of lean body mass may contribute to 20–30% of the total body weight you lose (1).

Lean body mass, also known as fat-free mass, is a measure of body composition. It is basically all of the body mass — water, bones and muscles — minus the fat.

The loss of lean body mass during dieting is mainly due to loss of muscle, but water may be lost as well (2).

Maintaining your muscle mass is very important for overall health. Fortunately, several strategies may help, including (3):

  • Eating enough protein (456).
  • Doing intense strength exercises (7).
  • Supplementing with high-quality protein, such as whey (8).

Article Reviewed

A group of researchers from McMaster University, Canada, examined the effects of high protein intake on body composition during a calorie-reduced diet combined with high-intensity strength exercise.

Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial.

Study Design

This 4-week, randomized, controlled trial examined whether the amount of protein eaten on a calorie-reduced diet during an intense strength exercise program would affect changes in body composition.

A total of 40 overweight young men followed a calorie-reduced diet, providing 60% of their calorie requirements, or 33 kcal for every kg (about 2.2 lbs) of lean body mass.

They also had exercise sessions on 6 days of the week, which involved strength training and high-intensity interval training.

The participants were randomly assigned to one of two diet groups:

  • High-protein diet: This diet provided 35% of calories from protein, 50% from carbs and 15% from fat. Daily protein intake was 2.4 g per kg of body weight.
  • Control diet: This diet provided 15% of calories from protein, 50% from carbs and 35% from fat. Daily protein intake was 1.2 g per kg of body weight.

The amount of protein in the control diet was similar to what many people normally get from their diet. In the high-protein group, however, the protein intake was 3 times higher than the recommended daily allowance.

All food was provided by the study kitchen. Participants in both groups also received beverages containing whey protein.

One of the protein beverages was consumed immediately after exercise, whereas the rest were consumed throughout the day.

At the start and end of the study, the researchers measured body composition.

Bottom Line: This was a 4-week, randomized, controlled trial examining the effects of a high-protein diet on changes in body composition during a calorie-reduced diet combined with strength exercises.

Finding 1: High Protein Intake Increased Lean Mass

Lean body mass increased significantly in the high-protein group, while it remained unchanged in those who got lower amounts of protein.

The chart below shows the differences between groups.

Protein and Control on Lean Mass Change

In both groups, lean muscle mass was preserved, despite significant weight loss.

This is supported by a previous study in overweight and obese women showing that a high-protein diet, providing 30% of calories from protein, increased lean mass during a calorie-reduced diet and a strength exercise program (6).

Bottom Line: The study showed that 1.2 g of protein/kg/day combined with strength exercises prevented loss of lean mass during a calorie-reduced diet. Higher amounts of protein, 2.4 g/kg/day, increased lean mass.

Finding 2: High Protein Intake Caused Greater Fat Loss

Participants in both groups lost significant amounts of fat. In fact, the participants’ weight loss was solely fat loss, while lean body mass was preserved.

This fat loss was significantly greater in the high-protein group, compared to the control group, as shown in the chart below.

Protein and Control on Fat Mass Change

These findings are strongly supported by previous studies showing that high-protein diets increase fat loss and preserve lean mass (9).

Bottom Line: The high-protein diet significantly reduced fat mass, compared to the lower-protein diet.

Limitations

This study was well designed and implemented, and appears to have no obvious limitations.

Summary and Real-Life Application

This study showed that supplementing with protein and doing high-intensity exercise prevented muscle loss and increased fat loss during a calorie-reduced diet.

What’s more, these strategies also significantly increased muscle mass.

If you want to improve the effectiveness of your dieting, consider eating more protein and doing some strength exercises.

This can help you retain your muscle mass, increasing the quality of your weight loss and improving your overall health.

Khorasan Wheat is Healthier Than Modern Wheat

Modern wheat has been criticized for being less nutritious than older varieties.

In fact, emerging evidence indicates that ancient Khorasan wheat is healthier than modern wheat (123).

To expand the evidence base, a group of scientists examined the health effects of Khorasan wheat on people with type 2 diabetes.

Their results were recently published in the European Journal of Nutrition.

Background

Modern wheat is a key component of many people’s diets.

However, a few previous studies suggest that modern wheat may be less nutritious than older varieties like spelt, emmer, einkorn or Khorasan wheat (4567).

Recently, a few human trials have focused on Khorasan wheat, also called Kamut. Khorasan wheat is an ancient type of wheat with grains that are larger than those of modern wheat.

Three randomized trials, all done by the same research group, have shown that Khorasan wheat may have health effects that are superior to modern wheat.

One 6-week trial in men and women with irritable bowel syndrome (IBS) showed that eating Khorasan wheat instead of modern wheat reduced inflammation and improved symptoms of IBS (3).

Another randomized trial in patients with heart disease found that a diet based on Khorasan wheat improved blood lipids, blood sugar control, inflammatory factors and antioxidant status, compared to modern wheat (2).

Finally, a trial in healthy individuals showed that Khorasan wheat had favorable effects on heart disease risk factors such as blood lipids, blood sugar, inflammatory markers and antioxidant status (1).

Article Reviewed

A group of Italian researchers compared the health effects of diets based on modern wheat and Khorasan wheat in people with type 2 diabetes.

A khorasan wheat‑based replacement diet improves risk profile of patients with type 2 diabetes mellitus (T2DM): a randomized crossover trial.

Study Design

This was a randomized, crossover trial examining the health effects of modern wheat and Khorasan wheat in people with type 2 diabetes.

A total of 21 diabetic men and women, with an average age of 64, participated in the study. The participants were assigned to two groups, in random order:

  • Khorasan wheat: This 8-week diet was based on wheat products made using organic, KAMUT® Khorasan wheat. The flour used was semi-whole.
  • Modern wheat: This 8-week control diet was based on wheat products made using organic, modern wheat. The flour used was semi-whole. Specifically, this was a mix of modern durum wheat and soft wheat varieties.

In both groups, the participants’ weekly consumption of wheat products included 500 grams of pasta, 250 grams of crackers and 250 grams of biscuits. Additionally, they ate 150 grams of bread each day.

The wheat products accounted for 50–55% of the participants’ daily calorie intake.
Since the study had a crossover design, all participants were in both groups on different occasions, separated by 8 weeks.

At the start and end of the study, the researchers measured fasting blood sugar, insulin, blood lipids, inflammatory markers and antioxidant status.

Bottom Line: This was a randomized, crossover trial examining the effects of replacing modern wheat with Khorasan wheat on blood sugar control and heart disease risk factors.

Finding 1: Khorasan Wheat Improved Blood Sugar Control

Eating Khorasan wheat reduced fasting levels of blood sugar by 9.1% and insulin by 16.3%, whereas modern wheat had no effects.

The difference between groups was significant only for insulin. The chart below shows the changes in blood sugar and insulin in both groups.

Wheat on Blood Sugar and Insulin

The researchers also estimated insulin sensitivity, which improved significantly when the participants consumed Khorasan wheat, compared to modern wheat.

These results are supported by two previous studies in healthy people and patients with heart disease (12).

Bottom Line: Consuming Khorasan wheat significantly improved fasting levels of blood sugar and insulin.

Finding 2: Khorasan Wheat Reduced LDL-Cholesterol

Replacing modern wheat with Khorasan wheat improved the blood lipid profile, reducing levels of total cholesterol by 3.7% and LDL-cholesterol by 3.4%.

In contrast, the diet that contained modern wheat seemed to increase total and LDL cholesterol levels slightly, although the effect was not statistically significant.

Two previous studies also support these results (12).

Bottom Line: Khorasan wheat improved cholesterol and LDL-cholesterol, compared to modern wheat.

Finding 3: Khorasan Wheat Improved Antioxidant Status

Previous studies have shown that high levels of blood sugar may impair antioxidant status, increasing the generation of harmful reactive oxygen species (ROS).

In the present study, eating Khorasan wheat significantly improved antioxidant status, whereas eating modern wheat had no significant effects.

In fact, Khorasan wheat improved total antioxidant capacity by 6.3%, and also reduced levels of ROS.

However, there were no significant differences between groups.

Wheat on Antioxidants

These findings are supported by a previous study examining the health effects of Khorasan wheat in healthy individuals (1).

Bottom Line: Eating Khorasan wheat significantly improved antioxidant status. However, there were no significant differences between groups.

Limitations

This study appears to have been designed and implemented well. Nonetheless, a few potential limitations should be mentioned.

First, the study size was small, which limits its statistical power.

Additionally, the paper doesn’t mention the fiber content of the wheat flours used in the study. Yet fiber is highly relevant, since it can affect various health markers.

Finally, the study was supported by a grant from Kamut Enterprises of Europe, which also provided the Khorasan wheat used in the study. However, the authors declared no conflicts of interest.

Bottom Line: This paper had a few limitations, including lack of information on the fiber content of the diets. Additionally, the study was funded by a company that sells Khorasan wheat.

Summary and Real-Life Application

In short, this study showed that when modern wheat accounts for about half of people’s daily calorie intake, replacing it with Khorasan wheat may have multiple health benefits.

These results are supported by a few previous studies by the same research group, and they were all funded by a Khorasan wheat producer. Although this does not discount the results, they should be confirmed by an independent research group.

If you want to improve your health, replacing your wheat with other fiber-rich grains may help. Khorasan wheat appears to be a good choice.

Organic Meat is Higher in Omega-3 and Polyunsaturated Fat

There are many reasons why people choose to eat organic food.

Some people believe that organic food is more nutritious than non-organic food. Numerous studies have looked into this, but their results are mixed.

An international team of scientists reviewed the results of 67 studies on conventional vs organic meat. Their results were published in the British Journal of Nutrition.

Background

The popularity of organic food has increased over the past few decades, and there are two main explanations for this:

  • Environment: People choose organic food because of environmental concerns.
  • Health: People choose to eat organic food for health reasons.

Many people believe that organic foods contain lower amounts of contaminants or are richer in healthy nutrients.

However, studies have provided mixed results and there has been some debate as to whether eating organic food has any health relevance (1).

Article Reviewed

This paper presents the results of a systematic review and meta-analysis on differences in the fat content of organic meat and non-organic meat.

Composition differences between organic and conventional meat: a systematic literature review and meta-analysis.

Study Design

The analysis included 67 studies published between 1992 and 2014. In 1992, the first organic farming regulations were introduced in the European Union.

Most of the included studies were from Europe, while rest were mainly from the US and Brazil.

The studies examined the nutritional content of various types of meat, but most of them focused on beef, lamb, goat, pork and chicken.

Three main types of studies were analyzed:

  • Comparison studies: Measurements of the nutritional content of meat from organic and non-organic farms in the same country or region.
  • Controlled experiments: Measurements of meat from experimental animals bred according to organic or conventional standards.
  • Basket studies: Measurements of organic and conventional meat from retail outlets.

The researchers mainly examined the content of polyunsaturated fatty acids (PUFAs) and omega-3 PUFAs, but the amount of other fats was also examined.

Bottom Line: This meta-analysis compared the fat content of organic meat and non-organic meat, focusing on polyunsaturated and omega-3 fatty acids.

Finding 1: Organic Meat is Higher in Polyunsaturated Fat

When all meat types were analyzed together, organic meat turned out to be 23% higher in polyunsaturated fat (PUFA), compared to non-organic meat.

However, when meat types were analyzed separately, significant differences in PUFA content were only found in chicken and pork.

This also applied to omega-6 and omega-3 PUFAs. The levels of omega-6 were, on average, 16% higher in organic meat. Similarly, the levels of omega-3 were 47% higher in organic meat.

When the omega-3 content of individual meat types was analyzed separately, significant differences were detected in chicken meat only.

The study found no significant differences in individual PUFAs, such as EPADHA or CLA, or the ratio of omega-6 to omega-3.

Bottom Line: Organic meat contained significantly more polyunsaturated fat, compared to conventional meat. It also contained higher amounts of omega-6 and omega-3 fat.

Finding 2: Organic Meat is Higher in Monounsaturated Fat

Organic meat was also 8% higher in monounsaturated fat.

When meat types were analyzed separately, monounsaturated fat levels were higher in pork and chicken only.

Conversely, the saturated fat content was similar in both organic and non-organic meat.

Bottom Line: Organic meat was significantly higher in monounsaturated fat, compared to non-organic meat.

Explanations

The nutrient content of meat ultimately depends on what the animal ate.

For this reason, the results of the present study are primarily explained by differences in feed or forage, although breed choice may also play a role.

Here are a few factors that may affect the fat content of meat:

  • Fresh forage: Pasture-raised or grass-fed meat contains higher levels of PUFAs and omega-3s. Animals on organic farms are often raised this way (23).
  • Type of forage: Organic farms often use a mixture of grass and clover, and clover-fed animals tend to have more omega-3s in their meat (45).
  • Concentrated feeds: Non-organic farms tend to use greater amounts of concentrated feeds based on grains or legumes, instead of pasture or grass (6).
  • Animal breed: Organic farmers may prefer more traditional breeds. Studies have shown that breed choice may affect the fat content of meat (2).

Bottom Line: The feed of animals on organic farms is often different from animals on non-organic farms, which affects the meat’s fat composition.

Limitations

Although the meta-analysis showed some significant differences between organic and non-organic meats, the individual studies provided mixed results.

For this reason, the strength of the evidence was estimated to be moderate. According to calculations, there was also some evidence for publication bias.

Otherwise, the meta-analysis itself appears to have been executed well.

Bottom Line: This meta-analysis seems to have been of high quality. However, the quality of the evidence was considered moderate, and the included studies provided mixed results.

Summary and Real-Life Application

This study showed that organic meat is, on average, significantly richer in polyunsaturated and monounsaturated fat, compared to non-organic meat.

This also applied to the levels of omega-3 and omega-6, whereas the ratio of omega-3 and omega-6 remained the same in both organic and non-organic meat.

The study’s authors speculate that eating organic meat may provide health benefits, especially if you eat a lot of meat.

However, randomized, controlled trials are required before any conclusions can be reached about the health relevance of these findings.

Weight Loss Changes the Gut Microbiota

The gut microbiota is one of the most highly active areas of research in nutrition.

Recently, a team of researchers examined the effects of a weight-loss program on the gut microbiota of obese individuals.

Here we discuss their main results, recently published in PLOS ONE.

Background

The gut microbiota appears to play a role in obesity and metabolic disorders, as discussed in our previous research review.

What you eat significantly affects the types of bacteria that thrive in your gut. These bacteria may also respond to sudden dietary changes or weight loss (12345).

This is because the bacteria feed on what you eat. What’s more, individual species of bacteria are often highly selective, feeding only on certain food components.

In this way, your diet can influence health through its effects on the gut microbiota.

Article Reviewed

A team of German scientists examined changes in the gut microbiota during a weight-loss program in obese people.

Characterization of the Gut Microbial Community of Obese Patients Following a Weight-Loss Intervention Using Whole Metagenome Shotgun Sequencing.

Study Design

This observational study examined changes in the gut microbiota during and after a weight-loss program in obese adults.

The researchers also wanted to find out if bacteria in stool samples could predict successful weight loss, or if the microbiota of people with metabolic syndrome or non-alcoholic fatty liver disease differed from that of healthy individuals.

The weight-loss trial lasted for one year. It involved a 3-month, very low-calorie diet (800 kcal/day) using a dietary formula enriched in inulin.

After that, the participants gradually replaced the formula with real food, and started weight maintenance. Additionally, the program involved exercise and behavioral therapy. These results and methods are described elsewhere (6).

In the present observational study, 16 obese individuals who participated in the trial were chosen based on their weight-loss success.

These 16 individuals were followed for two years — for the duration of the weight-loss trial and for another year afterwards.

Based on their weight-loss success, they were divided into two groups:

  • Persistent weight-loss success: A total of nine participants were successful in maintaining a 10% weight loss for one year after the weight-loss trial finished.
  • No persistent success: Seven of the participants were not successful in maintaining their weight.

The researchers analyzed the participants at the start of the study and after 3, 6, 12, 18 and 24 months. Using DNA sequencing, they measured the types and numbers of bacteria in stool samples.

Bottom Line: This was an observational study examining changes in the gut microbiota during and following a weight-loss trial. It also investigated whether the microbiota profile could predict weight-loss success.

Finding 1: Weight Loss Changed the Gut Microbiota

The study detected around 2,000 different types of bacteria in the participants’ stool samples. There was high individual variability in the microbiota profile, and some species were only found in one or a few of the participants.

The microbiota turned out to be quite stable during the weight-loss trial. Yet, the researchers detected 56 species of bacteria whose numbers changed significantly, mainly during the three months of calorie restriction.

Most notably, the following groups increased in counts: AlistipesLachnospiraceaeEthanoligenens and Holdemania.

HIV patients have lower levels of Alistipes than healthy people. However, some studies also link high levels with an increased health risk (7891011).

Only one group, Roseburia, decreased significantly. This group of bacteria convert fiber into butyrate, a healthy short-chain fatty acid.

Previous studies have shown that counts of Roseburia decrease during a low-carb, weight-loss diet among obese individuals (1213).

However, these changes were only temporary. After the 3-month weight-loss period, the counts of these bacteria gradually returned to initial levels.

When the whole 2-year study period was examined, only Akkermansia increased significantly. Specifically, it increased 11-fold, from 0.26 to 2.9% of total counts.

Bottom Line: The gut microbiota in obese adults changed during the weight-loss program, which involved an inulin-enriched, calorie-reduced diet.

Finding 2: Certain Groups of Bacteria Predicted Successful Weight Loss

Participants who consistently lost weight over the 2-year study had a slightly different microbiota at the start of the study, compared to those who were unsuccessful.

Specifically, they had a microbiota rich in the following groups of bacteria:

  • Alistipes.
  • Pseudoflavonifractor.
  • Ethanoligenens.
  • Gordonibacter.
  • Symbiobacterium.

The level of weight loss was also linked with increases to the numbers of bacteria of the genus Akkermansia in stool samples.

Studies show that high counts of Akkermansia are linked with a reduced risk of obesity and metabolic disorders. It may also reflect a healthy gut microbiota (1415).

By looking at food diaries, the researchers couldn’t find any dietary patterns explaining these differences.

Bottom Line: Successful weight loss was linked with higher initial counts of certain bacteria, such as Alistipes. Weight loss was also associated with higher counts of Akkermansia throughout the study.

Finding 3: The Ratio of Firmicutes and Bacteroidetes Was Not Linked With Obesity

Previous observational studies indicate that a high ratio of bacteria in the groups Firmicutes and Bacteroidetes (FB) is linked with increased body weight (1617).

In an attempt to explain this, scientists have speculated that Firmicutes may increase calorie absorption. In fact, they convert fiber into short-chain fatty acids, such as butyrate, which are absorbed by the cells lining the colon (18).

However, the current study did not find the ratio of FB to be significantly associated with body weight. This is consistent with other observational studies (192021).

These inconsistencies might be explained by genetic differences. One recent study suggests that numbers of Firmicutes may depend on individual genetics, whereas numbers of Bacteroidetes are mainly influenced by diet (22).

Bottom Line: Unlike some studies, this study did not find a significant link between the ratio of Firmicutes and Bacteroidetes and body weight.

Finding 4: Metabolic Syndrome Was Associated With a Different Microbiota Profile

The ratio of Firmicutes and Bacteroidetes was significantly higher (0.64) in those with metabolic syndrome at the start of the study, compared with those who were “healthy” obese (0.27).

Counts of Akkermansia were also lower in those with metabolic syndrome.

Additionally, the researchers compared the bacterial composition of people with non-alcoholic fatty liver disease (NAFLD) to those who didn’t have it.

These analyzes were done at the end of the study, to minimize the influence of the weight-loss trial.

They found several significant differences. Participants with NAFLD had:

  • Lower counts of Subdoligranulum, which are also lacking in patients with cirrhosis (23).
  • Lower counts of Lactococcus, which produce lactic acid from glucose and are used in the production of fermented dairy products, such as cheese. They may slow the development of colitis in mice (24).
  • Higher counts of Paraprevotella.

Bottom Line: Metabolic syndrome and non-alcoholic fatty liver disease were linked with differences in the gut microbiota.

Limitations

This study had several limitations. First, it was an observational study that couldn’t demonstrate causation.

Apart from the weight loss, several other factors were likely to have affected the microbiota. These include the probiotic inulin in the weight-loss formula (2526).

Second, the study was very small, including only 16 obese adults. This limited its statistical power.

Third, the participants were selected to reduce individual variability. For this reason, the results may not apply to all obese people.

Bottom Line: This observational study has a few limitations, including small size. It also can’t demonstrate causation, and its findings may be limited.

Summary and Real-Life Application

In short, this study indicates that the bacterial composition of stool samples may be used to predict success during a weight-loss program.

Specifically, high levels of Akkermansia were the strongest predictor of weight-loss success. However, these findings have no real-life application for weight loss.

Yet they are important to science, helping us understand what role the gut microbiota plays in obesity, weight loss and health.

Protein Reduces Appetite More Than Carbs and Fat

Eating protein leads to a greater reduction in appetite, compared to fat or carbs.

However, no previous studies have looked into the effects of specific proportions of protein, carbs and fat in a systematic, dose-response manner.

For this reason, scientists examined the effects of five drinks containing different proportions of these nutrients.

Background

Protein is generally considered to be the most filling macronutrient, whereas fat is the least filling. However, not all studies support this (12345).

This may be because protein and carbs suppress the hunger hormone, ghrelin, more than fat (67).

Another hormone that may be involved is the satiety hormone, glucagon-like peptide-1 (GLP-1). However, it’s currently unclear which macronutrient has the greatest effect on GLP-1 (89).

Article Reviewed

Scientists from Lund University, in Sweden, examined how different macronutrient proportions affected calorie intake, appetite hormones and appetite.

Protein-Enriched Liquid Preloads Varying in Macronutrient Content Modulate Appetite and Appetite-Regulating Hormones in Healthy Adults.

Study Design

This was a randomized, crossover trial examining the effects of liquid meals — varying in protein, fat and carbs — on appetite, appetite hormones and calorie intake.

A total of 36 healthy men and women participated in the study.

They were assigned to five different liquid meals, which they received on separate days in a random order:

  • Low-protein, low-carb, high-fat drink (LP/LC:HF): 8.9% of calories from protein, 28% from carbs and 63.1% from fat.
  • High-protein, low-carb, medium-fat drink (HP/LC:MF): 40% of calories from protein, 18.5% from carbs and 41.5% from fat.
  • Low-protein, high-carb, low-fat drink (LP/HC:LF): 8.9% of calories from protein, 71.1% from carbs and 20% from fat.
  • High-protein, medium-carb, low-fat drink (HP/MC:LF): 40% of calories from protein, 46.8% from carbs and 13.2% from fat.
  • Medium-protein, medium-carb, medium-fat drink (MP/MC:MF): 24.4% of calories from protein, 50.4% from carbs and 25.2% from fat. This drink was replicated three times.

These liquid meals were based on milk protein isolate, rapeseed oil and a mixture of maltodextrin and table sugar. All of them contained 502 calories (2,100 kJ), and had the same volume of 670 mL.

After finishing the drink on each of the seven test days, the participants rated their appetite every 30 minutes until they had a lunch test meal.

During the same period, the researchers collected blood samples every hour. The blood samples were analyzed for the appetite hormones, ghrelin and GLP-1.

The purpose of the lunch test meal was to measure calorie intake. It was served 3.5 hours after the breakfast, and was based on pasta. The participants were encouraged to eat as much as they wanted.

Bottom Line: This randomized, crossover study examined the effects of liquid meals, varying in protein, carbs and fat, on appetite hormones, self-rated appetite and calorie intake.

Finding 1: Protein Tended to Lower Appetite

Every half an hour after finishing the test drink, the participants were asked to rate their feelings of appetite on a visual analog scale (VAS).

The VAS included the following feelings:

  • Hunger.
  • Desire to eat.
  • Fullness.
  • Prospective food consumption.

The researchers found that subjective ratings for fullness were significantly greater after HP/MC:LF than after LP/LC:HF.

Similarly, prospective food consumption ratings were 12% lower after the intake of HP/MC:LF, and 11% lower after the intake of HP/LC:MF, compared to LP/LC:HF.

The findings are presented in the chart below:

Fullness and Consumption on VAS

However, there were no significant differences in any of the ratings between HP/MC:LF and LP/HC:LF, indicating that carbs may have some filling effects as well.

Overall, protein appeared to be the most filling macronutrient, while fat was the least filling. No significant differences in hunger or desire to eat were seen.

Bottom Line: Protein reduced self-rated appetite more than carbs and fat, and appears to be the most filling of the three macronutrients.

Finding 2: Calorie Intake Was Unaffected

There were no significant differences in how the meals affected calorie intake at lunch, 3.5 hours after they were consumed.

Some evidence indicates that liquid calories have weaker effects on appetite and calorie intake, compared to solid calories (10).

Also, the effects of these drinks on appetite may have faded 3.5 hours afterwards.

Bottom Line: The various liquid meals had no significantly different effects on calorie intake at a lunch eaten 3.5 hours afterwards.

Finding 3: Protein Increased Levels of GLP-1

Circulating levels of the appetite-suppressing hormone, GLP-1, were higher after the HP/LC:MF drink, compared to the other liquid meals.

This can be seen in the chart below:

Specifically, the levels of GLP-1 were generally 13–19% higher after the HP/LC:MF drink. This suggests that the appetite-suppressing effects of protein may be at least partly due to increases in GLP-1.

However, fat appeared to increase GLP-1 to some extent as well. These findings are supported by several previous studies (91112).

Conversely, no significant changes in the hunger hormone, ghrelin, were detected between liquid meals.

Bottom Line: Protein appeared to increase circulating levels of the appetite-suppressing hormone, GLP-1.

Limitations

Although the study’s design did not have any serious shortfalls, a few limitations should be mentioned.

First, including both men and women caused significant variations in calorie intake. This might have masked the effects of the liquid meals on calorie intake at lunch.

Additionally, the generalizability of the findings is limited. There is some evidence that liquid calories have weaker effects on appetite than solid calories (10).

Second, the drinks were not typical breakfast foods. One study indicates that novelty may affect satiety (13).

Finally, not all types of protein, carbs and fat affect appetite the same (141516).

Bottom Line: The study’s findings may not be generalized to all situations. For example, the liquid form of the drinks may have affected the results.

Summary and Real-Life Application

This study showed that protein reduces appetite more than carbs and fat. On the other hand, fat appeared to be less filling than protein and carbs.

Simply put, if you want to lose weight, adding more protein to your diet may help curb your appetite.

Low-Calorie Sweeteners May Help You Lose Weight

Replacing sugar with low-calorie sweeteners can reduce your calorie intake, and may lead to weight loss.

However, some people claim that low-calorie sweeteners promote weight gain.

For this reason, a group of scientists assessed the overall evidence in a systematic review and meta-analyses of studies in both animals and humans.

Background

Low-calorie sweeteners are widely used throughout the world. They can be added to food, but are also found in processed foods and diet sodas.

The most common low-calorie sweeteners include acesulfame-Kaspartamesaccharinstevia and sucralose.

Even though low-calorie sweeteners contain less calories than sugar, some researchers have speculated that consuming them may lead to weight gain (123).

Low-calorie sweeteners might affect body weight in several ways:

  • Calorie intake: Replacing sugar with sweeteners may cause you to eat more later on (4).
  • Label awareness: When food or drinks are labeled as low-calorie, some people may eat larger portions, eat more of other foods or eat more later on (5678).
  • Added sweetness: Sweetness might increase calorie intake by making foods more satisfactory or pleasant to eat (9).
  • Energy balance: Low-calorie sweeteners may disrupt how the body associates sweetness with calorie intake, impairing energy balance (10).

Article Reviewed

A team of European researchers from the International Life Science Institute looked at how low-calorie sweeteners affect body weight and calorie intake.

Does low-energy sweetener consumption affect energy intake and body weight? A systematic review, including metaanalyses, of the evidence from human and animal studies.

Study Design

This was a systematic review and meta-analysis examining the effects of consuming low-calorie sweeteners on calorie intake or body weight.

Several meta-analyses were conducted on different types of studies published before February 1st, 2015. These included intervention studies, randomized controlled trials, observational studies and animal studies.

Randomized, Controlled Trials (RCTs)

The review included 56 randomized, controlled trials or intervention studies that were divided into two categories, depending on their duration:

  • Short-term: RCTs that were shorter or equal to one day in length.
  • Long-term: RCTs that lasted for 10 days or longer.

Observational Studies

The review included the results of 12 observational studies, but only nine were used in meta-analyses.

All of these were prospective cohort studies, which measured habitual intake of sugar-sweetened beverages or diet beverages at one time point, and then followed the participants for more than one year.

This allowed the researchers to find out if sugar or low-calorie sweeteners were associated with changes in body weight.

Animal Studies

The researchers reviewed 62 articles, which reported the results of 90 studies examining the effects of low-calorie sweeteners on mice or rats.

These studies were divided into three groups, depending on their purpose:

  • Forced consumption: These studies examined the effects of forced consumption of low-calorie sweeteners.
  • Voluntary consumption: These studies examined the effects of voluntary consumption of low-calorie sweeteners.
  • Learning studies: These studies tested the hypothesis that rats fed low-calorie sweeteners will stop associating sweetness with additional calories.

Bottom Line: This analysis combined the results of randomized controlled trials, observational studies and animal studies published before 2015.

Finding 1: Low-Calorie Sweeteners Reduce Short-Term Calorie Intake

A total of 56 randomized, controlled trials, or intervention studies, lasting less than one day, were included in this systematic review.

These studies examined the effects of consuming low-calorie sweeteners on subsequent or total calorie intake.

The results of these studies were combined in a meta-analysis. Their main results are presented below.

Low-Calorie Sweeteners vs. Sugar

The meta-analysis showed that consuming low-calorie sweeteners, rather than sugar, significantly reduced overall calorie intake in both adults and children.

In addition, the analysis found that people tended to compensate for the reduced calorie intake by eating more at a subsequent meal. However, the calorie compensation was only partial.

Low-Calorie Sweeteners vs. Unsweetened Beverages/Food

Beverages or foods sweetened with low-calorie sweeteners did not significantly affect calorie intake, compared to the same foods without low-calorie sweeteners.

Similarly, diet beverages did not significantly affect calorie intake, compared to water.

Low-Calorie Sweeteners in Capsules vs. Placebos

When low-calorie sweeteners were given in capsules, they tended to reduce calorie intake, compared to placebo capsules.

One study found that taking a capsule containing aspartame, an amount similar to that found in diet sodas, reduced calorie intake, compared to a placebo (11).

The reason for these effects is unknown.

Summary

Overall, these studies consistently found that eating low-calorie sweeteners instead of sugar before a meal significantly reduced short-term calorie intake. On average, the difference was 94 calories.

The effects of eating low-calorie sweeteners were similar to drinking plain water.

Bottom Line: The results of short-term intervention studies suggest that consuming low-calorie sweeteners reduces short-term calorie intake.

Finding 2: Low-Calorie Sweeteners Reduce Long-Term Calorie Intake and Body Weight

This systematic review included a number of long-term intervention studies, ranging from 10 days to 3 years.

Calorie Intake

Nine intervention studies reported results for calorie intake.

Three of the studies found that consuming low-calorie sweeteners caused a significantly lower calorie intake (121314).

Conversely, three studies found no significant difference (151617).

The rest did not report the results of tests for statistical significance (181920).

Body Weight

A total of 10 long-term, interventional studies examined the effects of low-calorie sweeteners on body weight.

Five studies showed that consuming low-calorie sweeteners had significant benefits:

  • One study of obese women linked consuming aspartame-sweetened foods and beverages to greater weight loss and less weight regain (15).
  • Another study linked sugar supplements to increased calorie intake and weight gain, while artificial sweeteners had no adverse effects (12).
  • An aspartame-sweetened beverage reduced body weight in men, but not women. The same beverage, sweetened with high-fructose corn syrup, increased body weight (20).
  • This 18-month trial in children found that replacing sugary soda with diet soda reduced body weight and fat accumulation (21).
  • A 12-month weight-loss trial showed that drinking an artificially sweetened beverage led to greater weight loss than plain water (22).

Conversely, the other half of the studies found no significant improvements, compared to sugar or water (1617192324).

These studies were combined in a meta-analysis, which found that consuming low-calorie sweeteners led to a smaller weight gain, or greater weight loss, than sugar.

Summary

In short, the meta-analysis showed that eating low-calorie sweeteners caused a significant weight loss of about 3 lbs (1.35 kg).

Bottom Line: The meta-analyses of the RCTs showed that consuming low-calorie sweeteners reduced calorie intake and body weight.

Finding 3: Observational Studies Provide Inconsistent Results

A total of 12 observational studies examined the effects of diet sodas on body weight.

Overall, the results were mixed:

  • Higher risk of obesity: Five studies found that diet sodas were associated with a higher risk of obesity (325262728).
  • Lower risk of obesity: Six studies showed that diet sodas were linked with a lower risk of obesity (29303132).

Meta-analyses combining the results from nine of these studies found no significant associations between diet sodas and changes in body mass index (BMI).

However, inconsistencies in the studies’ findings make it difficult to interpret the results. Additionally, observational studies cannot prove causation.

Bottom Line: The observational studies provided inconsistent findings. The meta-analysis found no significant links between low-calorie sweeteners and BMI.

Finding 4: Low-Calorie Sweeteners Do Not Affect Body Weight in Animals

The majority of animal studies suggest that eating low-calorie sweeteners does not affect body weight.

Forced Consumption

The review included 45 articles on 47 studies where rats or mice were fed specific amounts of low-calorie sweeteners.

The majority of the studies found no significant effects of low-calorie sweeteners on body weight.

However, 18 studies that used higher doses showed that low-calorie sweeteners decreased body weight. Conversely, a few studies reported significant increases in body weight:

  • One study showed that saccharin increased body weight when it made up 1% of the diet, but higher doses had no effects (33).
  • Other studies, using lower doses of saccharin, also found no significant effects (343536).
  • When saccharin, cyclamate, acesulfame-K or aspartame were added to drinking water, only saccharin and cyclamate significantly increased body weight (37).
  • Another study found that low doses of cyclamate caused significant weight gain, but later studies were unable to replicate these findings (383940).

Voluntary Consumption

The review included 10 articles, reporting the findings of 21 studies in which rats were given the chance to eat artificial sweeteners.

Most of these studies, which offered a 0.1–0.2% saccharine solution or water, found no significant effects of saccharine on body weight (4142434444).

However, a few studies found that adding saccharin (0.2%) to water-mixed lab chow led to significantly greater calorie intake and weight gain (46).

Another study found that yogurt sweetened with aspartame or saccharin caused greater calorie consumption and weight gain, compared to yogurt sweetened with sucrose (47).

Learning Studies

The review included seven articles discussing 22 learning studies.

A total of 14 studies (64%) showed that rats with access to food with low-calorie sweeteners gained more weight than those with access to glucose-sweetened food.

The relevance of these studies for humans remains unclear.

Bottom Line: When low-calorie sweeteners improve the taste of food, they may increase body weight in animals. However, the majority of studies suggest that low-calorie sweeteners, on their own, do not affect body weight.

Limitations

This systematic review and meta-analysis had a few limitations.

First, it did not differentiate between the various types of low-calorie sweeteners. These may have different effects on body weight and health.

Second, some of the authors have ties to companies that produce low-calorie sweeteners, potentially creating a conflict of interest.

Summary and Real-Life Application

The majority of the evidence shows that using low-calorie sweeteners instead of sugar is beneficial, or at least neutral, when it comes to weight.

Another recent meta-analysis reached a similar conclusion (48).

If you prefer to sweeten your food, replacing sugar with low-calorie sweeteners may be an effective weight loss strategy, when combined with other lifestyle changes.

Matured Hop Extract May Reduce Belly Fat

For those trying to lose weight, weight loss supplements are a popular choice.

When combined with dieting and exercise, supplementing may be useful, but the weight loss benefits are usually modest.

Recently, hops have been studied for their potential weight loss benefits. This randomized controlled trial examined the effects of matured hop extract on weight loss in overweight adults. Below is a detailed summary of its findings.

Background

Hops are a type of flower, widely grown for the brewing industry.

They are an ingredient in most beers, providing the bitter flavor. They also have strong antibacterial properties, which suppress the growth of undesirable bacteria, while favoring the activity of brewer’s yeast (1).

Apart from their practical application in brewing, studies suggest that some of the active constituents of hops may have health benefits (234).

These include iso-alpha-acids — bitter constituents of beer — that are formed from alpha-acids in hops during the brewing process (235).

Evidence indicates that iso-alpha-acids may promote weight loss in humans and mice (67).

However, their intense bitterness makes them unsuitable for use in supplements. For this reason, researchers have started investigating less bitter alternatives, such as matured hop extract.

Article Reviewed

Japanese researchers investigated the effects of matured hop extract, containing matured hop bitter acids (MHBAs), on belly fat and body weight.

Matured hop extract reduces body fat in healthy overweight humans: a randomized, double-blind, placebo-controlled parallel group study.

Study Design

This randomized controlled trial examined the effects of matured hop extract on belly fat and body weight in healthy, overweight Japanese adults.

A total of 200 overweight men and women, aged 20 to 65 years, participated in the study. They were randomly assigned to one of two groups:

  • Matured hop extract: Daily for three months, the participants consumed 350 mL of a drink containing matured hop extract (MHE), providing 35 mg of matured hop extract bitter acids (MHBAs).
  • Placebo: Instead of consuming MHE, the participants consumed 350 mL of a control drink daily for three months.

Both beverages looked and tasted the same. They were based on water, containing around 1.05 grams of carbs and 5.25 grams of fiber (resistant maltodextrin).

At the beginning, midpoint and end of the study, the researchers measured body weight, belly fat (using CT scanning) and total body fat percentage (using bioelectrical impedance analysis).

Bottom Line: This was a randomized controlled trial examining the effects of supplementing with matured hop extract on body weight and belly fat.

Finding: Matured Hop Extract Reduced Belly Fat and Body Weight

Total belly fat decreased in both groups, but significantly more so for those who supplemented with matured hop extract, compared to the placebo.

The decrease in abdominal skin fat was not significantly different between groups.

The supplements also led to a slight decrease in body weight and body mass index (BMI). What’s more, the body fat percentage was slightly lower at the end of the study.

The chart below shows the changes in body weight, body mass index (BMI) and body fat percentage in both groups.

MHE and Placebo on Weight, BMI and Fat

These findings are supported by previous studies examining the health effects of iso-alpha-acids, which are derived from hops during brewing (67).

However, this is the first study to show that matured hop extract has a similar benefit.

Bottom Line: Supplementing with matured hop extract significantly reduced belly fat and body weight, compared to a placebo.

How Does Hop Extract Reduce Body Weight?

The reason why matured hop extract stimulates weight loss is not entirely clear.

One study in mice suggests that oxidized alpha-acids (MHBAs) may enhance fat burning in brown fat tissue (8).

Specifically, the alpha-acids increased heat production (thermogenesis) by speeding up the rate at which the mice burned calories in brown fat tissue. Higher activity of brown fat tissue has been associated with a lower body fat content in humans (9).

However, no alpha-acids were detected in the matured hop extract used in the current study, suggesting that other compounds may be at work.

Simply put, matured hop extract might promote weight loss by activating brown fat tissue, but further studies are needed to fully understand how this works.

Bottom Line: The reason why matured hop extract promotes weight loss is unclear. One previous study suggests that it may increase the amount of calories burned in brown fat tissue.

Why Did Both Groups Lose Belly Fat?

Interestingly, the participants in both groups lost significant amounts of belly fat.

This is a good example of a placebo effect, illustrating why placebo/control groups are necessary for clinical studies.

The psychological effects of participating in a supplemental weight loss study, and expecting certain benefits, may lead to marked improvements in body weight.

Participants may have unconsciously changed their habits — eating, exercise, sleep, smoking and drinking — during the study, even though they were told not to.

The authors speculated that psychological effects or seasonal variation may have been responsible.

It’s also plausible that resistant maltodextrin, a type of fiber added to the beverages, may have contributed to the decrease in belly fat (10).

Because of the additional weight loss caused by the placebo effect and/or fiber, the actual benefits of the matured hop extract were probably much lower than observed.

Bottom Line: Participants in both groups lost significant amounts of belly fat. The exact cause of the weight loss is unknown, but may be explained by a placebo effect and/or the fiber added to the beverages.

Limitations

According to the authors, the main limitation is the study’s short duration. It’s unclear if the weight loss benefits of matured hop extract are sustained in the long term.

It’s also unclear if the results can be generalized to severely obese individuals or other ethnicities. In the current study, the participants were overweight, with a BMI ranging from 25 to 30.

Finally, nine of the paper’s authors were employees of the study’s sponsor — Kirin Company, a corporation that specializes in beverage production. The same people collected, analyzed and interpreted the data, creating a conflict of interest.

Bottom Line: The findings may not be generalized to obese individuals and the long-term effects are unclear. There was also a conflict of interest.

Summary and Real-Life Application

In short, this study showed that supplementing with 35 grams of matured hop extract bitter acids may slightly reduce body fat, especially belly fat.

Why it works is not entirely clear, but previous animal studies suggest it may increase the amount of calories burned in brown fat tissue.

However, before any strong claims can be made, further studies by independent research groups are required.

Early Life Gut Microbiota is Affected by Maternal Weight Status

The bacteria that live in our digestive system significantly influence our health in a number of ways.

Commonly known as the gut microbiota, these bacteria can be either beneficial or harmful, all depending on what types of bacteria are present and their relative amounts.

A recent review discussed the development of the gut microbiota early in life, focusing on how it’s influenced by maternal weight status.

Below is a summary of the review’s main points.

Article Reviewed

This was a scientific review on the gut microbiota during infancy and the factors that affect it.

Microbial transmission from mothers with obesity or diabetes to infants: an innovative opportunity to interrupt a vicious cycle.

Early Development of the Gut Microbiota

The gut microbiota is believed to play a key role in the development of many chronic diseases, as discussed in a previous review.

For this reason, maintaining a healthy and balanced microbiota is important for health.

The gut microbiota of infants is highly variable between individuals. It also fluctuates over time, reaching stability at around age two (12).

Some evidence suggests that the infant microbiota may influence the gut environment later in life, possibly affecting health (3).

Bottom Line: Studies suggest that the gut microbiota of infants may affect health later in life.

How Do We Inherit Microbes From Our Mother?

We may inherit microbes from our mother in several ways:

  • In the uterus: Recent studies suggest that the developing fetus may be colonized by bacteria living in the uterus (45).
  • During birth: The type of birth may have considerable effects on the gut microbiota early in life. Being born the natural way is generally considered more beneficial than being delivered via a cesarean section (67).
  • While breastfeeding: Breastmilk contains bacteria such as Bifidobacteria and Lactobacillus. More importantly, it contains prebiotics that support growth of beneficial bacteria (8).

Bottom Line: Children are colonized by maternal bacteria when they are born and while they are breastfeeding. Recent studies suggest that unborn children may also be colonized by bacteria living inside the uterus.

What Factors Affect the Microbiota in Infants?

Various factors may affect the development of the gut microbiota in young children.

These include type of birth, breastfeeding, maternal health status and metabolism, weight gain during pregnancy, genetics and use of antibiotics.

These are discussed in greater detail below.

Maternal Dietary Intake, Obesity and Diabetes

Our health later in life may be affected by nutrient excess or deficiency while we were still in the womb (91011).

In fact, maternal obesity and diabetes are among the strongest risk factors for these metabolic disorders in children (1213).

What’s more, the newborns of obese or diabetic mothers have higher amounts of liver fat, increasing their risk of developing non-alcoholic fatty liver disease as they grow older (1415).

Attempting to explain this, some researchers have speculated that bacterial toxins, “leaking” from the gut into the bloodstream of obese mothers, may affect the development of the fetus (16).

There is also some evidence that maternal obesity may influence the gut microbiota in early infancy.

For example, bacteria belonging to the class Gammaproteobacteria are among the first to dominate the microbiota in young infants.

Although Gammaproteobacteria promote inflammation, they may be necessary for the normal development of the immune system – preventing the risk of autoimmunity in the gut.

A few studies in humans and animals indicate that the levels of Gammaproteobacteria are lower in the offspring of obese mothers (1718).

Bottom Line: Having an obese and/or diabetic mother is strongly associated with an increased risk of developing these disorders. However, the role of the gut microbiota in this relationship is unclear.

Cesarean Delivery

Children who are born the normal way are colonized by bacteria that live in their mother’s birth canal and intestinal tract.

Conversely, children that are delivered via a cesarean section are initially colonized by bacteria that live on their mother’s skin (67).

The way children are born can make its mark on the gut microbiota for up to two years (619).

However, observational studies suggest that its health effects may persist for longer.

Being born via a cesarean delivery is associated with a 46% greater risk of obesity at age seven, and a 20% increased risk of type 1 diabetes, compared to children born naturally (2021).

Bottom Line: Being born via a cesarean section affects the development of the gut microbiota. It has been linked with a higher risk of childhood obesity.

Breastfeeding

Breastmilk contains several compounds that are important for the development of a healthy gut microbiota (22).

These include human milk oligosaccharides, which function as prebiotic fiber, stimulating the growth of beneficial Bifidobacteria (8).

Human milk is also a source of microbes, mostly Bifidobacteria and Lactobacillus, which are also a part of the normal microbiota in healthy infants (23).

For these reasons, formula-fed infants have a lower diversity of Bifidobacteria in their gut, compared to breastfed infants (24).

However, not all milk is the same. The breastmilk of obese women seems to be slightly different from that of normal-weight women, containing higher levels of inflammatory markers, insulin and sugar (2526).

These differences might affect infants’ gut microbiota, but the health relevance is unclear (27).

Nevertheless, all women are encouraged to breastfeed, regardless of their weight status. Breastmilk has various benefits for young children (28).

What’s more, several observational studies suggest that breastfeeding may reduce the risk of obesity in children (7293031).

Bottom Line: Breastmilk has beneficial effects on the gut microbiota in children, and may even reduce the risk of childhood obesity.

Antibiotics

Some scientists are concerned that using antibiotics may cause an imbalance in the gut microbiota.

Adding to these concerns, several observational studies suggest that using antibiotics during the first two years of life may increase the risk of childhood obesity (3233).

What’s more, one study found that when mothers were given antibiotics during the second or third trimester of pregnancy their children were 84% more likely to become obese at age seven (20).

Bottom Line: Using antibiotics may imbalance the gut microbiota, at least temporarily. Some observational studies suggest that taking antibiotics during early infancy may increase the risk of obesity.

Ways to Improve the Gut Microbiota in Infants

In addition to breastfeeding, supplementing with probiotics and prebiotics may lead to significant improvements in the gut microbiota.

Studies in mice and humans show that probiotics and prebiotics may improve the gut microbiota, and reduce body weight and inflammation (343536).

Additionally, some studies in pregnant women indicate that supplementing with probiotics may affect the gut microbiota composition of their children (373839).

One randomized controlled trial in 122 mothers and their children examined the effects of supplementing with Lactobacillus rhamnosus and Bifidobacter lactis.

The study showed that supplementing from week 36 of pregnancy until delivery increased the counts of beneficial Bifidobacteria in the infants’ gut when they were three months old (37).

Bottom Line: Exclusive breastfeeding for the first 6 months of life promotes a healthy gut microbiota. After that, supplementing with pro- and prebiotics may provide an added benefit.

Summary and Real-Life Application

In short, multiple factors affect the development of the gut microbiota in infants.

Being born via a cesarean section, or having an obese or diabetic mother, is linked with an increased risk of an imbalanced gut microbiota and obesity.

Conversely, breastfeeding and taking probiotics is associated with improvements in the gut microbiota and a reduced risk of developing obesity.

Glycotoxins May Impair Insulin Sensitivity

Glycotoxins are a group of compounds that have been associated with an increased risk of type 2 diabetes and several other chronic diseases.

Recently, a team of scientists investigated the effects of a diet low in glycotoxins on insulin sensitivity in healthy, overweight people.

Background

Glycotoxins, also known as advanced glycation end products (AGEs), are a group of compounds formed when proteins react with sugar.

They are naturally formed in the body, but may be harmful if present in high amounts for a long time (1).

There are several ways that you may be exposed to high levels of glycotoxins:

  • Processed food: Many processed foods are high in glycotoxins, especially those that are high in fat (2).
  • Cooking: Glycotoxins are formed when foods are cooked, especially with high-temperature dry heat (2).
  • Meat intake: Roasted, fried or grilled meat contains high glycotoxin levels (23).
  • Sugar intake: Eating sugar may also increase glycotoxin levels in blood (4).

Glycotoxins have been associated with many chronic diseases, but few controlled trials have examined their effects in humans.

In mice, long-term consumption of high amounts of glycotoxins impairs insulin sensitivity, promoting the development of type 2 diabetes (5678).

Additionally, several human studies indicate that a diet low in glycotoxins may improve insulin sensitivity in patients with type 2 diabetes as well as in healthy, obese individuals without diabetes (91011).

Article Reviewed

A group of researchers examined the effects of a diet low in glycotoxins on insulin levels and sensitivity.

Diet low in advanced glycation end products increases insulin sensitivity in healthy overweight individuals: a double-blind, randomized, crossover trial.

Study Design

This was a randomized crossover trial examining the effects of a diet low in glycotoxins on insulin levels and sensitivity.

A total of 20 healthy, overweight adults participated in the study. They were assigned to two groups in a random order:

  • High-glycotoxin diet: For two weeks, the participants adhered to a diet high in glycotoxins, similar to a typical Western diet.
  • Low-glycotoxin diet: For two weeks, the participants adhered to a diet low in glycotoxins.

Since the trial had a crossover design, all participants were in both groups at different study periods, separated by a 4-week washout period.

All food was provided by the study kitchen. Both diets contained the same amount of calories, and the proportion of calories from protein, fat and carbs were matched. The diets also contained many of the same foods.

At the start and end of each period, the researchers measured fasting insulin and assessed insulin sensitivity, using high-standard techniques.

Additionally, two types of glycotoxins were measured in the diet, blood and urine: N-carboxymethyl lysine (CML) and methylglyoxal-derived hydroimadazolidine (MG-H1).

One type of advanced lipoxidation end product (ALE) — N-carboxyethyl lysine (CEL) — was also measured.

Bottom Line: This was a randomized, crossover trial examining the effects of a diet low in glycotoxins on insulin sensitivity.

Finding: Eating Less Glycotoxins Improved Insulin Sensitivity

Eating less glycotoxins caused a significant increase in insulin sensitivity, whereas eating higher amounts tended to impair insulin sensitivity.

Specifically, insulin sensitivity increased by 19% in the low-glycotoxin group, and decreased by a non-significant 11% in the high-glycotoxin group.

These results are shown in the chart below.

Glycotoxins on Insulin Sensitivity

Several other human trials support these findings. However, they all had several limitations, which weakened their findings (91011).

How glycotoxins affect insulin sensitivity is currently unknown, but may be related to their ability to promote oxidative stress and inflammation (1213).

In the study, there were no significant differences in insulin levels between diets.

Bottom Line: A diet low in glycotoxins significantly improved insulin sensitivity, while insulin levels remained unchanged.

Limitations

This study was designed and implemented well, and used high-standard analytical techniques.

However, the researchers couldn’t rule out that insulin sensitivity might have been affected by factors other than glycotoxins.

Additionally, the study’s results can’t be generalized to people with type 2 diabetes.

Further studies are needed to find out if going on a low-glycotoxin diet improves diabetics’ symptoms.

Summary and Real-Life Application

In short, the study suggests that eating a diet low in glycotoxins for two weeks improves insulin sensitivity, compared to a diet high in glycotoxins.

Nonetheless, further studies are needed before the health effects of glycotoxins are fully understood.

Water vs Diet Soda: Which is Better for Weight Loss?

Many people think drinking diet beverages is a great way to lose weight.

However, most dietary recommendations say pure water is best. Recently, a team of scientists from Iran and the UK delved into this issue.

Here is a detailed summary of the results, recently published in the American Journal of Clinical Nutrition.

Background

Sugar-sweetened beverages have long been linked to weight gain (12).

For this reason, beverages with low-calorie sweeteners have become a popular alternative for those who wish to maintain or lose weight (3).

Although the evidence is mixed, some studies actually suggest that diet beverages may be associated with weight gain as well (4).

Article Reviewed

A group of researchers from Iran and the UK compared the effectiveness of diet beverages and water on weight loss.

Effects on weight loss in adults of replacing diet beverages with water during a hypoenergetic diet: a randomized, 24-wk clinical trial.

Basic Study Design

This was a 24-week, randomized weight loss trial in 62 healthy, overweight and obese women. The participants ranged in age from 18 to 50 years.

Before the study started, all of the participants regularly consumed diet beverages.

The participants were randomly assigned to one of two groups:

  • Diet beverage group: Participants were provided with 250 ml (8.5 oz) of a diet beverage and were told to drink it after lunch, 5 times per week.
  • Water group: Participants in this group stopped drinking diet beverages and replaced them with equal amounts of water, provided by the study staff.

However, it is important to note that the contents of the diet beverage are not specified.

This study was designed to promote weight loss of 7–10%, during the research period. This involved a calorie-restricted diet that was high in carbs (60%), but low in fat (23%) and protein (17%).

Additionally, participants had professional support throughout the study, and were encouraged to gradually increase physical activity to 60 minutes, 5 days of the week.

The researchers measured body weight, insulin, blood sugar and blood lipids at the beginning, middle and end of the study.

Bottom Line: This was a randomized weight-loss trial in overweight and obese women. It compared the effectiveness of drinking diet beverages or replacing them with water.

Finding 1: Water is More Effective for Weight Loss

Participants in both groups achieved significant weight loss during the study.

However, drinking pure water resulted in a 13.6% greater weight loss than diet beverages. However, the difference was small, amounting to 2.6 pounds, or 1.2 kg.

The chart below shows the difference in weight loss and body mass index (BMI) between groups.

Overall, drinking water led to greater weight loss and improvements to BMI, compared to drinking diet beverages.

Bottom Line: The study showed that drinking pure water leads to greater weight loss, compared to drinking diet beverages.

What Do Other Studies Say?

In general, these results are supported by studies showing that increased water intake can help with weight loss (5).

However, there are mixed results in studies that compared water and diet beverages. For example, one randomized controlled trial found that diet beverages caused significantly greater weight loss, compared to water (6).

Another trial found that weight loss was similar among those who drank water or diet beverages (7).

The cause of these inconsistencies is unknown, but they might be due to differences in the type of diet beverage or a lack of compliance.

Despite these disparities, the present study is significant because it is different from previous trials.

This study is the first to examine the effectiveness of replacing diet beverages with water, during a weight loss program, where participants were obese, regular drinkers of diet beverages.

Bottom Line: The study showed that replacing diet beverages with water led to greater weight loss. However, other studies have found no difference, and some have even found diet beverages to lead to more weight loss than water.

Finding 2: Water Caused Greater Improvements in Blood Sugar Control

Drinking pure water, rather than diet beverages, caused significantly greater improvements in blood sugar control.

The chart below shows the improvements in insulin and blood sugar levels 2 hours (2-hbs) after eating 75 grams of glucose.

Water and Diet Beverage on Insulin

Insulin resistance also improved significantly.

Additionally, although fasting blood sugar levels improved overall, the difference between groups was not statistically significant.

Bottom Line: Overall, the weight loss program caused significant improvements in blood sugar control. Drinking water caused greater improvements in fasting insulin and insulin resistance.

Finding 3: Water and Diet Beverages Had Similar Effects on Blood Lipids

The weight loss program caused substantial improvements in blood lipids in both groups.

The chart below shows the changes in both groups.

Water and Diet Beverage on Cholesterol

These improvements were not significantly different between groups.

Bottom Line: The blood lipid profile improved in both groups. However, there was no significant difference between groups. In general, this indicates that water and diet beverages may have similar effects on blood lipids.

Limitations

The study appears to have been well designed and executed.

However, the paper itself has one major limitation. It fails to provide information about the contents of the diet beverage used in the study, which makes interpreting the results difficult.

There are many different artificial sweeteners in the food supply. Different types may have different effects.

Also, according to self-reported food records, calorie intake and carb intake reduced slightly more in the water group, compared to the diet beverage group.

This may explain some of the differences between groups.

Bottom Line: The study appears to have been designed well. However, the paper fails to specify the contents of the diet beverage, which makes interpreting the results difficult.

Summary and Real-Life Application

In short, this study indicates that pure water promotes significantly greater weight loss, compared to diet beverages.

Additionally, drinking water caused greater improvements in insulin sensitivity, indicating improved metabolic health.

However, it is impossible to reach any conclusions based on this study alone, because other studies have shown completely different effects.

At the end of the day, this may depend on the individual.

If you like diet drinks, and they help you stick to a healthy diet, then there is probably no need to stop drinking them.

But if you are drinking them, and you have trouble losing weight or want to speed things up, removing these drinks may or may not help.

It’s definitely something that is worth experimenting with, but the science is not settled on this issue yet.

Everything in Moderation: Helpful or Harmful Advice?

Most dietary guidelines recommend dietary diversity.

In other words, they say that people should eat lots of different kinds of food in moderation. “Everything in moderation” is a popular phrase.

However, it is unclear whether following this recommendation has any effects on people’s health.

A group of scientists tried to answer this question by examining the association of dietary diversity and abdominal obesity and type 2 diabetes.

Background

Dietary diversity has never been clearly defined.

Most previous studies simply define it as the number of different foods you eat in a certain time frame.

However, this leaves out some important factors, such as how the foods are spaced out or how different the foods actually are.

A few previous studies have investigated the effects of a diverse diet, but most focused only on diversity within selected food groups.

For example, one observational study links eating many different types of fruits and vegetables to a reduced risk of type 2 diabetes (1).

Another observational study showed that eating a variety of vegetables may help prevent weight gain. However, eating many varieties of unhealthy foods may increase the risk of weight gain (2).

These studies suggest that dietary diversity can affect health in different ways, depending on what foods are eaten.

Article Reviewed

A team of researchers from the US examined how a varied diet affects the risk of obesity and type 2 diabetes.

Everything in Moderation — Dietary Diversity and Quality, Central Obesity and Risk of Diabetes.

Basic Study Design

This study was a secondary analysis of the Multi-Ethnic Study of Atherosclerosis, a prospective observational study in people of Caucasian, Hispanic, African and Chinese descent.

The purpose of this secondary analysis was to examine the association of dietary quality with abdominal obesity and type 2 diabetes.

A total of 2505 men and women, 45 to 84 years old, participated. None of them had type 2 diabetes. At the beginning of the study, their diet was estimated using a food frequency questionnaire.

To estimate dietary diversity, the researchers assessed:

  1. Count: How many different foods were eaten more than once per week.
  2. Evenness: How the diversity was spread out over the week.
  3. Dissimilarity: How different the foods were.

After 5–7 years, the study staff measured body weight and waist circumference. Fasting blood sugar was measured 10–11 years later.

Bottom Line: This was a prospective observational study examining how the risk of weight gain and diabetes is linked with dietary diversity or quality.

Finding 1: Dietary Diversity Is Not Associated With Dietary Quality

The major finding of the study is that a diverse diet is not necessarily a healthy diet.

The count and evenness measures of dietary diversity were only weakly linked with dietary quality.

Conversely, greater food dissimilarity was linked with lower dietary quality — a lower intake of healthy foods and a higher intake of unhealthy foods.

Bottom Line: A diverse diet is not necessarily a healthy diet. Eating many different types of food doesn’t guarantee that those foods are high in quality.

Finding 2: Dietary Diversity May Promote Weight Gain

Greater food dissimilarity was linked with higher gain in waist circumference, which is a measure of belly fat.

This is probably because a higher food dissimilarity was associated with a higher intake of unhealthy food.

Supporting this, one observational study showed that greater dietary variation was associated with a higher intake of unhealthy foods (3).

Additionally, observational studies suggest that high dietary diversity may lead to increased calorie intake and fat gain (234).

Bottom Line: Eating many different kinds of food does not necessarily prevent belly fat. In fact, increasing diversity may even promote higher calorie intake and weight gain.

Finding 3: A Varied Diet Was Not Linked With Type 2 Diabetes

During the 10-year follow-up period, 24% of the participants were diagnosed with type 2 diabetes.

However, this was not linked to dietary diversity. Likewise, no significant associations were found when foods were categorized as either healthy or unhealthy.

In fact, a greater variety in fruit and vegetable intake did not seem to be associated with a reduced risk of type 2 diabetes.

This is inconsistent with one observational study suggesting that eating a greater variety of fruits and vegetables may help prevent type 2 diabetes (1).

On the other hand, the present study found high dietary quality to be significantly associated with less risk of type 2 diabetes.

This means that diets should focus on high-quality food, rather than on diversity.

Bottom Line: A diverse diet did not protect against type 2 diabetes. However, a high-quality diet was linked with less risk of type 2 diabetes.

Limitations

The use of food frequency questionnaires to assess dietary variation is one of the main limitations of the study.

Food frequency questionnaires can only include a few types of food. For example, the fruit and vegetable category included only 23 different foods.

For this reason, dietary diversity may have been biased or underestimated.

Additionally, this was an observational study, not a controlled trial. Although the study was designed well, it can not prove causation.

For example, it can show that people who eat a diverse diet have a higher risk of weight gain, but it can not prove that the diverse diet itself caused the weight gain.

Bottom Line: The study was designed well. However, the use of food frequency questionnaires to assess dietary intake limited the researchers’ ability to fully evaluate dietary diversity.

Summary and Real-Life Application

In short, this study does not support the idea that eating whatever you want, even in moderation, promotes a healthier diet.

However, this doesn’t mean dietary diversity is a bad thing.

For example, in developing countries with limited food supplies, greater dietary diversity would increase nutrient intake (5).

It just means that, for many people, diet should focus on eating quality, whole foods — but not trying to eat “everything in moderation.”

Slow Down! Eating Too Fast May Cause Weight Gain

Eating too fast has often been linked to weight gain, yet the available evidence is inconclusive.

For this reason, a team of Japanese researchers conducted a meta-analysis that combined the results of several previous studies.

Here is a detailed summary of their findings, recently published in the International Journal of Obesity.

Background

How eating behavior affects weight gain and obesity is an area of active research. One interesting part of this is eating rate, or the speed of eating.

Because eating speed is so important, slow and thoughtful eating is often recommended as an effective weight loss strategy (1).

This is supported by several observational studies, suggesting that eating slowly may reduce the risk of obesity (2345).

However, the available evidence is not entirely conclusive (67).

Article Reviewed

A team of Japanese scientists conducted a systematic review and meta-analysis of observational studies about the association of eating speed with obesity.

Association between eating rate and obesity: a systematic review and meta-analysis.

Basic Study Design

This meta-analysis included data from 23 observational studies that investigated the link between eating speed and obesity.

Using the combined dataset, the researchers tried to answer the following two questions:

  1. Is eating speed associated with body mass index (BMI) or obesity?
  2. Is eating speed associated with weight gain?

In this study, “eating speed” refers to how quickly people finished a meal.

Bottom Line: This was a meta-analysis, combining the results of 23 observational studies. It examined the association between eating speed and weight gain or obesity.

Finding 1: Fast Eaters Are Much More Likely to Be Obese

The study showed that fast eaters tend to have a higher average BMI. They are also more likely to be obese, compared to those that eat slower.

The results can be seen in the plot below, which shows the obesity risk in relation to eating speed.

As you can see in the plot above, obesity is very strongly linked to eating quickly.

This association was weaker in diabetics, but was otherwise consistent across subgroups.

Bottom Line: This study shows that people who eat more quickly tend to have higher BMIs and obesity rates, compared to people with less fat mass.

Finding 2: Fast Eating is Linked to Weight Gain

The analysis included three studies examining the association of eating rate and weight gain or the risk of developing obesity.

One study in firefighters showed that those who ate quickly at the station gained 9.9 lbs (4.5 kg) over a 7-year period, compared to only 6.8 lbs (3.0 kg) among those who ate slowly (8).

The second observational study found that those who ate quickly gained 2.4 lbs (1.1 kg) more weight over an 8 year period, compared to those who ate more slowly (9).

Finally, the third study showed that university students who finished their meals quickly were at an increased risk of becoming obese (10).

Bottom Line: Overall, this meta-analysis suggests that eating quickly increases the risk of weight gain and obesity.

How Does Rate of Eating Affect Weight?

Other studies have proposed several possible explanations for the link between eating rate and obesity.

These include:

  • Greater calorie intake: Several observational studies and one meta-analysis indicate that a fast eating pace may lead to a higher calorie intake (111213).
  • Eating ahead of brain signals: Fast eaters consume more calories before the satiety (appetite-reducing) signals kick in (14).
  • Lower levels of satiety hormones: One study has shown that eating a meal quickly causes lower levels of satiety hormones, such as peptide YY and glucagon-like peptide-1 (15).

However, the present study does not support the above-mentioned theories. In this analysis, calorie intake turned out to be similar across different eating rates.

Instead, the authors suggested an alternative explanation.

Fast eaters may chew their food less than slow eaters. A lack of chewing may inactivate histamine, which is a type of neurotransmitter. This, in turn, may reduce fat burning (16).

Bottom Line: Several factors may explain how the speed at which you eat affects weight gain. The authors suggested that faster eating is linked to a reduction in fat burning.

Limitations

The study seems to have been well executed, but a few important limitations should be mentioned.

First off, this meta-analysis included only observational studies, which cannot prove a causal relationship. Randomized controlled trials are needed to establish causality.

Second, in all of the included studies, save one, eating speed was assessed from self-reports. This may have caused some inaccuracies.

Third, many of the included studies categorized eating rates differently.

Finally, most of the participants were Japanese. This limits the generalization of the results to other populations, who may have different dietary habits.

Bottom Line: The study included results from observational studies, which can’t demonstrate causality. Additionally, the participants were mostly Japanese and the results may not be generalized to all populations.

Summary and Real-Life Application

This meta-analysis clearly suggests that the speed of eating affects weight.

Faster eaters have higher BMIs and are much more likely to be obese. People who eat quickly also gain much more weight when followed for several years.

One study suggests that retraining eating behavior, by reducing portions and slowing down the speed of eating, can lead to significant weight loss (17).

However, randomized controlled trials are needed to confirm these findings, which for now are only observational in nature.

Meanwhile, eating slowly and without distraction is definitely very sensible advice.

Low-Fat vs. Higher Fat Diets: What’s Best for Weight Loss?

The effects of low-fat diets on weight loss have been debated for many years.

Even though a lot of researchers have studied this, the evidence is still inconclusive.

For this reason, a team of US scientists analyzed trials comparing the effectiveness of low-fat diets to other types of diets.

Background

Many studies have examined how macronutrients — carbs, fat and protein — affect weight loss, but the best ratio of the three has yet to be determined.

One common belief is that higher-fat diets cause weight gain. As a result, many weight-loss diets are low in fat.

This is mainly because fat contains more than twice as many calories as carbs and protein. So, gram for gram, replacing fat with another macronutrient should promote weight loss.

However, the evidence is inconsistent. Randomized controlled trials do not always find low-fat diets to be effective for long-term weight loss (1234).

Article Reviewed

A group of researchers conducted a meta-analysis of randomized controlled trials, comparing the effectiveness of low-fat diets with higher-fat diets for long-term weight loss.

Effect of low-fat diet interventions versus other diet interventions on long-term weight change in adults: a systematic review and meta-analysis.

Basic Study Design

This meta-analysis examined the effectiveness of low-fat diets for long-term weight loss, compared to other types of diets.

These included low-carb diets, higher fat diets or the participants’ normal diets.

The analysis included 53 trials and a total of 68,128 participants. All of the trials were long-term, lasting for more than 1 year.

However, they were not all weight-loss trials, and the low-fat diet ranged in fat content from under 10% of calories to under 30% of calories from fat.

Bottom Line: This meta-analysis assessed how low-fat diets affected weight loss, compared to low-carb diets, higher fat diets or no participants’ normal diets.

Sub-Analyses of the Main Study

Not all of the included studies provided the same results.

This inconsistency is, at least partly, explained by how the studies were designed.

For example, the present meta-analysis suggests that study intensity may have influenced the effectiveness of the investigated diets.

Study intensity depended on several factors, such as the level of support given to participants, and whether or not the diets were calorie-restricted.

For more accurate results, the researchers did a sub-analysis of studies with a similar intensity.

Bottom Line: In addition to combining the results of all studies, this meta-analysis also compared studies of similar intensity to minimize risk of bias.

Finding 1: Low-Fat Is Not Better Than Higher-Fat

The average weight loss of all the trials was 2.7 kg (6.0 lbs).

There were no significant differences in weight loss between low-fat and higher-fat diets, when all the studies were analyzed together. This is consistent with one previous meta-analysis (5).

On the other hand, the average weight loss was 3.8 kg (8.4 lbs) in the analyses of trials where the diets were also calorie-restricted.

When the study diets differed by more than 5% of total calories from fat, higher-fat diets led to significantly greater weight loss.

Also, if the change in circulating triglycerides differed by 0.06 mmol/L or more between diets, the higher-fat diet was more effective than the low-fat diet.

Simply put, when the studies were designed for weight loss, and compliance was adequate, higher-fat diets caused more weight loss than low-fat diets.

These results are not supported by a previous meta-analysis concluding that reducing total dietary fat leads to significantly greater weight loss, compared to other dietary patterns (6).

However, this previous analysis selected studies of shorter duration, excluded trials that had calorie-restricted diets, and didn’t take study intensity into account.

Bottom Line: Overall, low-fat diets are not more effective for weight loss than higher-fat diets. In fact, higher-fat diets were more effective than low-fat diets when they differed by more than 5% of calories from fat.

Finding 2: Low-Fat Is Not Better Than Low-Carb

When compared to low-carb diets, low-fat diets were found to be slightly less effective for weight loss.

This analysis found that, on average, low-carb diets caused 1.2 kg (2.5 lbs) more weight loss than low-fat diets.

These results are supported by previous meta-analyses, which estimated a 0.9–2 kg (2–4.4 lbs) greater weight loss on a low-carb diet, compared to a low-fat diet (78).

Bottom Line: Low-carb diets caused more weight loss than low-fat diets. This is also supported by previous studies.

Finding 3: Low-Fat Is Better Than Nothing

Low-fat diets were more effective for weight loss than no dietary intervention at all.

The analysis found that people on a low-fat diet lost 5.4 kg (11.9 lbs) more weight, on average, than those who did not alter their diet.

This indicates that low-fat diets are not completely useless for weight loss. Going on a low-fat diet is definitely a better weight loss strategy than continuing to eat a Western diet.

However, higher-fat and low-carb diets are even more effective.

These results are supported by one previous meta-analysis showing that low-fat diets caused greater long-term weight loss, compared to the participants’ regular diets (5).

Bottom Line: Low-fat diets caused significantly more weight loss than habitual diets. Although a low-fat diet is not the best option, it is much better than adhering to the typical Western way of eating.

Limitations

This meta-analysis appears to be as good as they get. The main limitation is the variability of the trials, since they differed considerably in design and intensity.

However, the researchers tried to minimize this bias by doing comparisons of similar-intensity studies.

Additionally, most of the studies allowed participants to eat on their own. Food was not provided or monitored, and the studies relied on self-reporting.

Bottom Line: This was a high-quality meta-analysis with no obvious design flaws. However, the strength of the evidence is limited by the variability and shortfalls of the included trials.

Summary and Real-Life Application

Simply put, low-fat diets are not the best option for weight loss.

However, they are better than no dietary changes at all. This study just shows that other diets, such as higher-fat and low-carb diets, are much more beneficial.

If you are considering going on a weight loss diet, then you don’t necessarily need to reduce your fat intake.

Instead, you should reduce the amount of carbs in your diet, while making your food choices healthier overall.

Are Energy Drinks Bad for Your Heart?

Energy drinks are very popular, especially among young people.

These beverages contain stimulants, such as caffeine, which are supposed to provide a physical and mental boost.

However, drinking too many energy drinks may have serious effects on heart function and other aspects of health (1234).

Today’s study takes a look at how energy drinks affect heart health.

Study Reviewed

Researchers from the Mayo Clinic in Minnesota conducted a small study on how energy drinks affect blood pressure, heart rate, blood sugar and norepinephrine levels.

A Randomized Trial of Cardiovascular Responses to Energy Drink Consumption in Healthy Adults.

Basic Study Design

This was a randomized, controlled crossover study that examined how energy drinks affect heart function. It included 25 healthy men and women, aged 26 to 31 years.

There were two study groups:

  • Energy drink: The participants drank 480 mL (16 fl oz) of Rockstar, a type of energy drink. It contained several stimulants: caffeine (240 mg), taurine (2000 mg), and extracts of ginseng root, milk thistle and guarana seed.
  • Placebo: Another day, the participants got the same amount of a placebo drink. It was similar to the energy drink, but didn’t contain any of the stimulants.

On both occasions, the participants were fasting. They also hadn’t had any energy drinks, coffee or alcohol for at least 24 hours prior to each study day. Additionally, all study drinks were finished within 5 minutes.

Since this was a crossover trial, the participants got both drinks in random order on separate days, with less than 2 weeks apart.

Before and after drinking the energy drink and the placebo, the researchers measured circulating levels of caffeine, blood sugar, norepinephrine, blood pressure and heart rate.

Blood pressure and heart rate were also measured while the participants were under 2 minutes of stress. Responses to three types of stress were measured: physical stress, mental stress and cold stress.

Bottom Line: This small, randomized, controlled crossover study examined the effects of an energy drink on blood pressure, heart rate, blood sugar and norepinephrine.

Finding 1: Energy Drinks May Increase Blood Pressure

Blood pressure increased after the energy drink, whereas the placebo drink did not cause any statistically significant changes in blood pressure.

The chart below shows the changes in mean blood pressure in both groups:

Energy Drink and Placebo on Blood Pressure

After the energy drink, systolic blood pressure increased by 6.2% and diastolic blood pressure increased by 6.8%.

Although the study did not examine how long the effects on blood pressure lasted, they were probably only temporary.

Blood pressure also rose during physical, mental and cold stress, but the energy drink didn’t add to this increase.

Additionally, the energy drink did not affect heart rate, which remained normal after both drinks.

Bottom Line: Blood pressure increased significantly after the energy drink. Conversely, the placebo drink did not lead to any significant changes.

Finding 2: Norepinephrine Increased More After the Energy Drink

Also called noradrenaline, norepinephrine is a stress hormone that helps prepare the body for action.

For this reason, its levels are lowest during sleep, and highest during periods of stress and/or fear. It is one of the body’s “fight or flight” hormones.

High levels of norepinephrine have been linked with an increased risk of heart disease in predisposed individuals (56).

In the present study, levels of norepinephrine increased after both drinks.

However, the rise was significantly higher after the energy drink, compared to the placebo.

The chart below shows the differences between groups:

Energy Drink and Placebo on Norepinephrine

As with the rise in blood pressure, the rise in norepinephrine was probably just temporary. Therefore, its health relevance is unclear.

Bottom Line: Norepinephrine levels increased after both the energy drink and the placebo. However, the increase was higher after the energy drink.

Finding 3: Blood Sugar Increased Similarly in Both Groups

Both the energy drink and the placebo drink contained equal amounts of sugar. For this reason, the blood sugar levels rose similarly after both drinks, as expected.

Several previous studies have shown that caffeine may blunt the insulin response to sugar intake for those who are not regular caffeine consumers (789).

However, this does not seem to be the case here.

Many of the participants might have been regular coffee drinkers, or the statistical power of the study was simply not great enough to detect the between-groups difference as significant.

Bottom Line: The energy drink and the placebo contained the same amount of sugar, and blood sugar levels increased similarly after both drinks.

Limitations

The main limitation of this study is the small number of participants. The study may not have had enough statistical power to detect smaller between-group differences.

Another limitation is that the energy drink contained several stimulants: caffeine, taurine, guarana, milk thistle and ginseng root. This makes it impossible to isolate the effects of the individual ingredients.

This study also only examined one energy drink, which contained a mixture of commonly used stimulants like caffeine. Other brands and products may have different ingredients.

Otherwise, this study appears to have been designed and executed well.

Bottom Line: The study’s main limitation is its small size and limited statistical power.

Summary and Real-Life Application

This small study shows that energy drinks may cause a sudden rise in blood pressure and norepinephrine.

The authors concluded that over time, these factors may possibly increase the risk of heart disease (610).

However, the extent of this risk is unclear, and needs to be studied further before any solid conclusions can be reached.

At the end of the day, energy drinks should be used sparingly, if at all. In addition to possibly harmful stimulants, they also contain sugar and other unhealthy ingredients.

Plain coffee is a much healthier alternative.

Eating Garlic Makes Men Smell More Attractive

Garlic is known for causing bad breath (12).

This is because it contains a gas called allyl methyl sulfide, which can also affect the smell of breast milk (34).

A team of researchers looked into the effects of garlic on sweat, particularly armpit odor. Here is a detailed summary of the results, recently published in Appetite.

Article Reviewed

A small team of scientists from the Czech Republic and Britain investigated the effects of garlic on men’s body odor.

Consumption of garlic positively affects hedonic perception of axillary body odour.

Basic Study Design

The purpose of the study was to test whether eating garlic would change the characteristics of men’s armpit odor, as judged by women.

The study was divided into three experiments, which included 42 men and 82 women. In each, the participants were randomly assigned to one of two groups:

  1. Garlic group: These men ate garlic, but the amount varied by experiment.
  2. Control group: The men in this group ate no garlic.

Each of the three experiments tested different amounts or forms of garlic:

  • Experiment 1: The body odor of 10 men was rated by 14 women. The garlic group got 6 grams of crushed, raw garlic, equivalent to 2 cloves of garlic.
  • Experiment 2: The body odor of 16 men was rated by 40 women. The garlic group ate 12 grams of crushed, raw garlic, equivalent to 4 cloves of garlic.
  • Experiment 3: The body odor of 16 men was rated by 28 women. The garlic group ingested 12 garlic capsules, each containing 1 gram of garlic extract dissolved in soybean oil, an amount equivalent to 12 grams of fresh garlic.

The experiments had a crossover design. This means that all of the men were in both control and garlic groups on different occasions, separated by one week.

To collect body odor, the male participants wore cotton pads in their armpits for 12 hours while fasting, immediately after eating the experimental meal.

Afterwards, the women sniffed the pads. They then ranked the odor for its intensity, attractiveness, pleasantness and masculinity, using a 7-point scale.

Bottom Line: This study examined the effects of garlic on the characteristics of men’s armpit odor, as rated by a group of women.

Finding 1: Garlic Improved Body Odor

In the first experiment, no significant differences were detected. However, when the amount of garlic was increased in experiments 2 and 3, the body odor of men who ate garlic was significantly less intense.

The chart below shows how eating garlic affected the intensity of body odor.

Why this happens is unclear. However, there is one plausible explanation. Fresh sweat produced in the armpits is virtually odorless, but after a while it starts to smell because of the action of skin bacteria (56).

Garlic is well-known for having potent antibacterial effects. It is possible that these antibiotics may find their way into sweat, reducing the activity or growth of the skin bacteria that cause unpleasant sweat odors (7).

For this reason, the findings of the study may not have been sex-specific, and might have provided similar results if men had ranked the body odor of women.

Bottom Line: After eating garlic, the armpit odor of men was less strong or intense. Hypothetically, garlic’s antibiotic effects might reduce the growth of skin bacteria responsible for strong body odors.

Finding 2: Garlic Decreased Masculinity

Experiments 2 and 3 found that the body odor of men who ate garlic was less masculine, compared to those who didn’t eat garlic. However, eating small amounts of garlic (experiment 1) had no statistically significant effect.

The chart below shows the effects of garlic on masculinity, in all three experiments.

This may be because women find strong or intense body odors as more masculine.

If the intensity of odor was rated as high, the masculinity rating of an odor tended to be high as well.

Bottom Line: The body odor of men who ate garlic was judged as less masculine. This is probably because the sweat of men who ate garlic also smelled less strong.

Finding 3: Garlic Increased Attractiveness

In the first experiment, no statistically significant differences were detected. Experiments 2 and 3, which used twice as much garlic, showed significant differences between groups.

The armpit odor of those who ate garlic was judged as more pleasant and attractive, compared to the odor of men who didn’t eat any garlic.

The chart below shows the differences between groups in all three experiments.

Graph of Garlic Attractiveness

This finding may be explained by the association of odor attractiveness and intensity. More intense body odors were ranked as less attractive.

Alternatively, the women might have subconsciously perceived the body odor of garlic-eating men as more attractive because it exhibited subtle signs of health.

In our opinion, however, this is a much less likely explanation.

Bottom Line: The armpit odor of men who ate garlic was rated more attractive, compared to the odor of those who didn’t eat garlic. This is presumably because garlic reduced the intensity of sweat odors.

Limitations

This study appears to have been conducted well, but has one limitation.

The number of participants was lower in experiment 1, which weakens the statistical power of the findings and makes comparisons between experiments difficult.

Summary and Real-Life Application

This study suggests that eating garlic improves armpit body odor, at least in men.

Garlic decreased odor intensity and increased attractiveness, as rated by women. However, it also decreased the perception of masculinity.

Although the real-life application of this study is questionable, the results are intriguing. Garlic may affect certain skin bacteria responsible for intense sweat odor.

Clearly, there is more to garlic than meets the mouth.

Sugary Drinks Make You Eat More

People who drink sugar-sweetened beverages tend to gain more weight over time.

However, it is not known whether all types of sugar are equally fattening.

For this reason, a team of scientists recently examined how different forms of sugar affect calorie intake.

Here is a detailed summary of their results, published in the American Journal of Clinical Nutrition.

Background

Sugar-sweetened beverages are a major source of calories in Western society (1).

Studies suggest that drinking sugar-sweetened beverages promotes excessive calorie intake, weight gain and obesity (2).

Several factors could explain this:

  • Liquid calories bypass the body’s appetite-regulating system. They are simply added on top of normal calorie intake (3456).
  • Fructose doesn’t stimulate insulin release when ingested. For this reason, it may not suppress appetite as strongly as glucose (7).

However, exactly how or why this happens is not fully understood, and further studies are needed.

Study Reviewed

Scientists from Seattle examined the effects of fructose-sweetened beverages on calorie intake, and compared it with beverages sweetened with glucose, high-fructose corn syrup or aspartame.

No difference in ad libitum energy intake in healthy men and women consuming beverages sweetened with fructose, glucose, or high-fructose corn syrup: a randomized trial.

Basic Study Design

This study was based on the secondary analysis of two randomized, controlled crossover trials.

The main purpose of this study was to examine the effects of fructose-sweetened beverages on calorie intake, and to compare it with glucose, high-fructose corn syrup (trial B) or aspartame-sweetened beverages (trial A).

Trial A

A total of 9 healthy, normal-weight adults participated in this trial. They were randomly assigned to one of three groups:

  • Fructose: For 8 days, the participants consumed 4 servings of a fructose-sweetened beverage every day.
  • Glucose: During the same period, the participants consumed 4 servings of a drink sweetened with glucose. A small amount of aspartame was also added to match the sweetness of the fructose.
  • Aspartame: In this control group, the participants consumed 4 servings of aspartame-sweetened beverages per day.

The amount of glucose and fructose consumed daily was equivalent to 25% of each subject’s estimated calorie requirement. Conversely, the aspartame-sweetened drink provided only 4% of their estimated calorie needs.

The study had a crossover design, which means that all participants were in each of the three groups on different weeks, separated by 20 days.

All participants spent 8 days in each group, during which the study kitchen provided them with standardized food, or an amount equivalent to 125% of their estimated calorie requirements.

Trial B

A total of 24 healthy adults completed this trial. Half of them were overweight or obese, whereas the rest were normal-weight.

They were randomly assigned to one of three groups:

  • Fructose: For 8 days, the participants consumed beverages sweetened with fructose. As in trial A, the daily amount was divided between 4 servings.
  • Glucose: Participants in this group consumed fructose-sweetened beverages instead of glucose. A small amount of aspartame was added to make the sweetness equal to that of the fructose beverage.
  • High-fructose corn syrup: In this group, the participants got beverages sweetened with high-fructose corn syrup, which is essentially a mixture of fructose and glucose. A small amount of aspartame was also added.

Otherwise, trial B was identical to trial A.

Bottom Line: This study used data from two small randomized controlled trials examining the effects of fructose on calorie intake, and comparing it with glucose, high-fructose corn syrup or aspartame.

Finding 1: Sugar-Sweetened Beverages Increased Calorie Intake

In trial A, calorie intake was significantly higher among those who got 25% of their estimated calorie needs from sugar-sweetened beverages, compared to those who got aspartame.

Glucose- and fructose-sweetened beverages increased calorie intake equally.

The chart below shows the differences in calorie intake between groups, presented as the percent of estimated calorie requirement:

Chart One on Sugars on Calorie Intake

These results are supported by studies showing that sugar-sweetened beverages consistently promote weight gain (26).

In the present study, body weight did not change significantly between groups. This is probably explained by the low statistical power of the study, and its short duration.

Bottom Line: Sugar-sweetened beverages increase calorie intake, compared to beverages sweetened with aspartame. For this reason, they may promote long-term weight gain.

Finding 2: Fructose and Glucose Increased Calorie Intake Equally

Fructose, glucose and high-fructose corn syrup all had similar effects on calorie intake. Also, no differences were detected when the participants were divided into subgroups based on gender or body weight.

The chart below shows the differences in calorie intake between groups in trial B, presented as the percent of estimated calorie requirement.

Chart Two on Sugars on Calorie Intake

These findings are in line with previous studies (89).

Bottom Line: Fructose, glucose and high-fructose corn syrup increased calorie intake to the same extent. Put simply, liquid sugar promotes weight gain, regardless of the type of sugar.

Limitations

The study was well planned and executed. However, it had several limitations.

First, both trials recruited a small number of participants, especially trial A, which included only 9 participants. This limited the statistical power, and means that smaller but significant findings may have been missed.

However, trial B included a greater number of participants than trial A, and was based on proper sample-size calculations.

Second, both trials were intentionally of short duration to prevent adverse health effects, such as weight gain. But this means that the results may not necessarily be generalized to longer periods.

Additionally, in trial A, the participants in the fructose and glucose groups were provided with more calories, or a total of 150% of their calorie requirements, compared to those in the aspartame group, which received only 129%.

This difference might have contributed to the differences in calorie intake between groups.

Finally, the participants were provided with a standardized diet that did not include snack foods high in sugar and fat. This limits the generalizability of the results further.

Bottom Line: The study was well planned and implemented. However, it had a few shortfalls that might have affected the results and limited the generalizability of the results.

Summary and Real-Life Application

In short, consuming sugar-sweetened beverages leads to a higher calorie intake, compared to aspartame-sweetened beverages.

Fructose, glucose and high-fructose corn syrup all had a similar effect. This indicates that liquid sugar increases calorie intake, regardless of the type of sugar.

Simply put, if you care about your weight, you should avoid sugar-sweetened beverages.

Eating Late at Night Burns Fewer Calories

Eating food causes a temporary increase in metabolic rate, or calories burned. This is known as diet-induced thermogenesis, or the thermic effect of food (TEF).

Some studies indicate that TEF may be higher in the morning. Therefore, a team of researchers set out to examine how meal timing affects TEF.

Here is a detailed summary of their findings, recently published in the International Journal of Obesity.

Background

The body’s metabolic activities fluctuate throughout the day. For example, the metabolic responses to a meal are different in the morning than later in the day.

Most notably, insulin sensitivity is higher in the morning, causing faster blood sugar clearance after a meal. It decreases as the day goes on, reaching its lowest point during the night (123).

Previous studies have also found that the rise in metabolic rate after a meal, or TEF, is higher in the morning than in the evening (45).

Although TEF is only responsible for about 10% of the body’s total calorie expenditure, it is believed to play a role in the development of obesity (6).

In fact, several observational studies suggest that consuming a large part of your daily calories in the evening is associated with an increased risk of obesity (789).

Additionally, one randomized weight-loss trial also showed that a high-calorie breakfast caused greater weight loss than a high-calorie dinner (10).

However, the available evidence is not entirely conclusive. Studies suggest that skipping breakfast, and eating more in the evening and afternoon, has no effect on calories burned over a 24-hour period (11).

What’s more, one large randomized controlled trial, which we reviewed last September, showed that skipping breakfast for 4 months has no effects on body weight in overweight and obese adults (12).

Article Reviewed

A group of researchers from Turin, Italy compared the effects of breakfast and dinner on blood sugar control and the post-meal increase in the body’s metabolic rate.

Is the timing of caloric intake associated with variation in diet-induced thermogenesis and in the metabolic pattern? A randomized cross-over study.

Basic Study Design

The main purpose of this randomized crossover trial was to compare the effects of breakfast and dinner on post-meal metabolic rate. It also examined the effects on blood sugar control and free fatty acids.

A total of 20 normal-weight men and women participated in the study. They were randomly divided into one of two groups:

  • Morning: Participants in this group got a standardized meal at 8 AM.
  • Evening: Participants in this group got an identical meal at 8 PM.

The meal had a relatively high protein content, or 30% of total calories. The fat and carb content were 31% and 39% of total calories, respectively.

A high protein content is known to promote calorie expenditure, or a greater thermic effect of food (1314).

The trial had a crossover design, which means that the participants who got breakfast on the first day got dinner a week later, and vice versa.

The researchers measured resting metabolic rate, blood sugar, insulin and free fatty acids before each meal and again after the meal was finished.

Bottom Line: This was a randomized crossover trial that compared the effects of a standardized high-protein breakfast and dinner on metabolic rate (calories burned), blood sugar control and free fatty acids.

Finding 1: Earlier Meals Burned More Calories

The amount of calories burned was significantly greater after the morning meal, compared to the later meal, as seen in the chart below.

Metabolic Rate and Meals Chart

These findings are supported by a few previous studies (45).

Several factors may explain these differences. First, levels of the hormone epinephrine are higher in the morning than later in the day. Epinephrine may increase metabolic rate (1516).

Second, insulin resistance may decrease metabolic rate, possibly explaining why it is lower in the evening (1617).

Bottom Line: An early meal caused a greater increase in metabolic rate and calorie expenditure than an identical meal eaten in the evening.

Finding 2: Earlier Meals Affected Free Fatty Acids Less

In the study, the levels of circulating free fatty acids (FFAs) increased less after the early meal, compared to the later meal.

FFA On Meals Chart

Previous studies support these results. Circulating FFAs have been reported to be higher around noon or in the afternoon, compared to early morning (118).

Although elevated levels of FFAs are perfectly normal after a meal that contains fat, increased base levels of FFAs have been associated with obesity, type 2 diabetes and metabolic syndrome (19).

Bottom Line: The levels of free fatty acids increased less after earlier meals, compared to meals eaten later on.

Finding 3: Earlier Meals Raised Blood Sugar Levels Less

Blood sugar and insulin levels were significantly lower after earlier meals, compared to later meals.

Glucose On Meals Chart

This aligns with previous studies (12).

A few factors may be responsible for these effects:

  • Gastric emptying is slower in the evening, possibly leading to more efficient carb absorption (2021).
  • Free fatty acids may impair blood sugar control (2223).
  • Hormones fluctuate throughout the day (242526).

Bottom Line: Later meals caused a greater increase in glucose and insulin levels, compared to earlier meals. This indicates that blood sugar control is not as efficient in the evening.

Limitations

This study appears to have been well designed and implemented. However, its results may not apply to all situations.

The test meal contained a relatively high amount of protein, or 30% of total calories. If the meal had contained a less protein, the differences resulting from timing may have been less pronounced.

Additionally, all of the subjects were of normal weight. These results need to be confirmed in overweight or obese people.

Bottom Line: The study was well planned and executed. However, the test meal had a high protein content and all participants were of normal weight, which may limit the generalizability of the results.

Summary and Real-Life Application

In short, this study suggests that meal timing is important for weight loss and maintenance.

An early meal resulted in more calories burned, compared to eating the same meal later on. The early meal also led to smaller increases in free fatty acids and blood sugar levels.

Taken together, the available evidence indicates that eating a greater proportion of calories earlier in the day, and avoiding big meals at night, may be useful for losing weight.

Probiotics May Lower Blood Sugar in Diabetics

Imbalanced gut microbiota may be one of the underlying causes of type 2 diabetes, and changing this environment may help improve symptoms.

Recently, a team of scientists examined the effects of beneficial, probiotic bacteria on blood sugar control in type 2 diabetics.

Here is a detailed summary of their findings, published in Clinical Nutrition.

Goat Milk in Jug

Background

Type 2 diabetes has been associated with dysbiosis — an imbalance in the bacterial community in the gut (1).

Two studies even suggest that high numbers of undesirable gut bacteria may play a direct role in the development of type 2 diabetes (23).

Supplementing regularly with probiotics may help change the gut environment. In diabetics, Lactobacillus probiotics may have beneficial effects on blood sugar control and blood lipids (4567).

Study Reviewed

A group of scientists from Brazil looked at the effects of probiotic supplementation on several markers of diabetes.

Clinical application of probiotics in type 2 diabetes mellitus: A randomized, double-blind, placebo-controlled study.

Basic Study Design

This was a 6-week, randomized controlled trial examining the effects of probiotics on blood sugar control, blood lipids and inflammatory markers.

A total of 45 men and women with type 2 diabetes participated in the study. They were randomly assigned to one of two groups:

  • Probiotic group: Participants in this group consumed 120 grams of fermented goat’s milk every day for 6 weeks. The milk contained two kinds of probiotics, Lactobacillus acidophilus and Bifidobacterium animalis.
  • Control group: Participants in this group consumed 120 grams of conventional, fermented goat’s milk per day. It contained the probiotic Streptococcus thermophilus.

At the beginning and the end of the study, the researchers measured blood sugar markers, insulin, blood lipids and inflammatory markers.

Bottom Line: This was a 6-week, randomized controlled trial examining the effects of probiotics on blood sugar control, blood lipids, inflammation and other health factors in people with type 2 diabetes.

Finding 1: Probiotics Improved Blood Sugar

HbA1c is short for glycated hemoglobin. It forms when hemoglobin, the protein that carries oxygen throughout the body, joins with sugar (glucose).

Your HbA1c levels indicate how high your blood sugar levels have been in the past weeks or months, on average.

Like HbA1c, fructosamine is a glycated protein that reflects blood sugar levels in the previous 2 or 3 weeks.

In the present study, HbA1c and fructosamine both decreased significantly in the group that received probiotics. The graph below shows the results for fructosamine:

Probiotics and Control on Blood Sugar

Conversely, fasting levels of blood sugar, insulin or insulin resistance did not change in either group. Taken together, these findings suggest that probiotics may improve blood sugar control in type 2 diabetics.

This is supported by previous studies showing that eating yogurt containing Lactobacillus acidophilus for 6–8 weeks may reduce blood sugar and HbA1c in diabetic individuals (45).

Bottom Line: Drinking goat’s milk containing Lactobacillus acidophilus and Bifidobacterium animalis appeared to improve fructosamine and HbA1c levels, compared to goat’s milk containing Streptococcus thermophilus.

Finding 2: Probiotics Improved Blood Lipids

There was a significant difference in the changes in total cholesterol and LDL-cholesterol between groups, as seen in the chart below.

Probiotics and Control on Cholesterol

Levels of total cholesterol and LDL-cholesterol increased significantly in the control group, but went down slightly in the probiotics group.

HDL-cholesterol and triglycerides did not change in either group.

Previous studies have also shown that Lactobacillus acidophilus may reduce total cholesterol and LDL-cholesterol in type 2 diabetics (67).

Bottom Line: Drinking milk containing Lactobacillus acidophilus and Bifidobacterium animalis promoted a better blood lipid profile, compared to milk that contained Streptococcus thermophilus.

Finding 3: Goat’s Milk May Reduce Inflammation

Systemic inflammation may be an underlying factor in the development of type 2 diabetes (8).

Therefore, the researchers measured levels of several inflammatory markers, including tumor necrosis factor alpha (TNF-α) and resistin.

TNF-α and resistin decreased significantly in both groups over the course of the study. For this reason, the researchers concluded that drinking fermented goat’s milk may improve inflammation.

Bottom Line: Drinking fermented goat’s milk that contained probiotics appeared to reduce inflammation. This happened in both groups.

Limitations

This study had several shortfalls.

First, levels of HbA1c were significantly higher in the probiotic group at the beginning of the study. This might have affected the decrease in HbA1c in the probiotic group.

Second, the control group got fermented milk that contained the probiotic bacteria Streptococcus thermophilus, which may have health benefits different from those of Lactobacillus acidophilus and Bifidobacterium animalis (9).

In a controlled trial, the experimental and control groups must not differ from each other except through the variables that are to be tested, which in this case are the probiotic effects of L. acidophilus and B. animalis.

For this reason, the study may not have had a true control group.

Bottom Line: The study’s design is questionable and it had a few limitations that make its results difficult to interpret.

Summary and Real-Life Application

In short, the study suggests that the probiotics Lactobacillus acidophilus and Bifidobacterium animalis may have health benefits in people with type 2 diabetes, compared to Streptococcus thermophilus.

They improved the blood lipid profile and appeared to have beneficial effects on blood sugar control.

This study adds to the growing evidence that probiotic bacteria can have wide-ranging health benefits.

Carbs Have No Effect on The Starvation Response

Sustained, long-term weight loss is difficult for many people. One reason is because the body adapts to weight loss, which is known as starvation response.

During starvation response, metabolic rate (or calories burned) is reduced. Dietary factors may also play a part, but studies debate this (123456).

Recently, a team of scientists looked into how carbs affect starvation response and body weight. Here is a detailed summary of their results, published in Obesity.

Study Reviewed

A group of scientists compared the effects of a moderate-carb diet and a high-carb diet on weight loss, body composition and starvation response.

Effects of Carbohydrate Quantity and Glycemic Index on Resting Metabolic Rate and Body Composition During Weight Loss.

Basic Study Design

This double-blind, randomized controlled trial investigated how carbs in calorie-restricted diets affect body weight, body composition, resting metabolic rate and starvation response. The participants were obese adults, aged 45 to 65 years.

The study was divided into 4 phases. The first three phases had a controlled diet, provided by the study’s kitchen. During the last phase, the participants were free to eat as much as they wanted to.

  • Phase 1. Weight maintenance: This 5-week phase determined how many calories participants needed to maintain a stable weight.
  • Phase 2. Experiment: In this 12-week phase, the participants were randomly assigned to one of four diets (see below). These 4 diets were calorie-restricted, and had about 67% of the calories required to maintain a stable weight.
  • Phase 3. Weight maintenance: During this 5-week phase, the participants had their calorie intakes adjusted so they would maintain their weight.
  • Phase 4. Follow-up: For 12 months, the participants selected and prepared their own meals, but were provided with instructions to follow their assigned diets.

The 4 diets assigned in phase 2 varied the amounts of carbs, as well as the glycemic index (GI). Those who ate fewer carbs ate more fat instead.

  • Moderate-carb, high-GI diet: This diet provided 54%, 29% and 16% of calories from carbs, fat and protein, respectively, and had a glycemic index of 80.
  • Moderate-carb, low-GI diet: This diet provided 54%, 31% and 16% of calories from carbs, fat and protein, respectively, and had a glycemic index of 51.
  • High-carb, high-GI diet: This diet provided 70%, 14% and 16% of calories from carbs, fat and protein, respectively, and had a glycemic index of 86.
  • High-carb, low-GI diet: This diet provided 68%, 16% and 15% of calories from carbs, fat and protein, respectively, and had a glycemic index of 59.

Throughout the study, the researchers measured body weight, body composition and resting metabolic rate. Starvation response was calculated as the difference between predicted and measured resting metabolic rate.

Of the 107 participants that initially started the study, 79 completed phases 1–3, but only 60 made it to the end.

Bottom Line: This was a double-blind, randomized controlled trial comparing the effects of moderate-carb and high-carb diets, and high- and low-GI diets, on starvation response, body composition and body weight.

Finding 1: Carbs Did Not Affect Starvation Response

At the end of phase 2, resting metabolic rate (RMR) was 6.5% lower, on average, compared to at the beginning of the study.

Some of the decline in RMR was predicted to happen with weight loss, but the actual measured reduction was slightly greater than predicted.

This difference, which amounted to 54 kcal/day, on average, was assumed to be accounted for by the starvation response. The chart below shows the differences in starvation response during phase 2 across groups.

Carbs and GI on Adaptation

Bottom Line: Neither the amount of carbs nor the glycemic index had any significant effects on starvation response or the total reduction in RMR during the study.

Finding 2: The Diets Caused Similar Weight Loss

On average, the study participants lost 7.5% of their original body weight during the study, mostly in phase 2. However, weight loss did not significantly differ across groups.

Carbs and GI on Weight Loss

These results indicate that when a calorie-controlled weight loss diet contains moderate to high amounts of carbs, variations in the ratio of carbs to fat do not change the effectiveness of the diet.

This study, however, did not compare the effectiveness of high- or moderate carb diets with a low-carb diet. A low-carb diet is much lower in carbs than the diets tested in the current study.

Bottom Line: Moderate-carb and high-carb diets had similar effects on weight loss. These results cannot be generalized to low-carb diets, which were not examined in the present study.

Finding 3: Glycemic Index Did Not Affect Weight Loss

The glycemic index measures how foods affect the rise in blood sugar after a meal. In the present study, weight loss did not significantly differ by the glycemic index of the diet.

This is supported by previous studies showing that the glycemic index of a particular diet has no effects on weight loss when calories are controlled (789).

Bottom Line: The glycemic index of the diets had no effects on weight loss in the current study.

Finding 4: Carb Amount Did Not Affect Weight Loss Quality

The quality of weight loss refers to how much fat mass is lost relative to muscle mass.

When you go on a weight loss diet, you usually lose both fat mass and muscle mass (lean mass), but the ratio may vary. If relatively little muscle mass is lost, the quality of the weight loss is high.

In the present study, neither the carb content nor the glycemic index (GI) of the diet had any effects on the ratio of the loss of fat mass and lean mass, as shown in the chart below.

Various factors may affect the quality of weight loss. These include strength exercises, protein intake and eating pattern.

However, the present study makes it clear that carbs are not one of those factors, at least not when the carbs are at moderate or high levels.

Bottom Line: Neither the carb amount nor the glycemic index of the diets had any effects on weight loss quality, or the ratio of the reduction in fat mass and lean mass.

Finding 5: Carb Amount Did Not Affect Weight Regain

During phase 4 of the study, the participants were allowed to eat as much as they wanted, but were given instructions to follow their diets from phase 2.

On average, the participants regained 4.3 kg (9.5 lbs) during phase 4, or about 58% of the weight they lost.

Weight regain did not differ across groups, and was not associated with variations in resting metabolic rate or the starvation response. This means that the amount of carbs eaten did not predict weight regain after dieting had stopped.

Bottom Line: The carb amount of the weight loss diets did not affect weight regain after dieting had stopped.

Limitations

This study does not have any serious weaknesses in its design or execution.

However, only 56% of participants made it to the end, which means the dropout rate was very high. There are also a few issues that limit how the results can be generalized.

First, the study compared moderate- to high-carb diets. The difference in the amounts of carbs on the high-carb (70%) and moderate-carb diets (54%) may not have been sufficient enough to cause significant differences in weight loss.

Second, the study wasn’t designed to cause a huge amount of weight loss. With greater energy restriction, the results might have been different.

Third, adherence to the diets may not have been perfect. In fact, there were some indications that calorie intake may have been slightly higher than prescribed.

Finally, calories were controlled in the current study. The results may have been different on an ad libitum (eat until fullness) diet.

Bottom Line: This study appears to have been well designed and implemented. However, the results cannot be generalized to low-carb diets, and the dropout rate was very high.

Summary and Real-Life Application

Starvation response was not affected by the amount of dietary carbs or the glycemic index, at least not when carb intake was moderate to high. Likewise, weight loss did not differ across groups.

This is not to say that reducing carbs can’t be beneficial for weight loss. Plenty of studies have shown that reducing carbs can be a very effective weight-loss strategy.

This study, however, replaced carbs with fat, while keeping protein intake unchanged. Additionally, it did not examine the effects of a low-carb diet.

The present findings are of limited use for people trying to lose weight. They are, however, of greater value for science, helping us understand how carbs affect body weight on a calorie-restricted diet.

A Healthy Body Clock May Reduce The Risk of Weight Gain

Many metabolic functions fluctuate throughout the day. These changes are regulated by your body’s internal clock, also known as the circadian rhythm.

Disrupting this system may contribute to weight gain and obesity.

Recently, a review article discussing the role of the body clock on weight maintenance was published in Obesity Reviews.

Article Reviewed

Researchers at the University of Leuven’s Gut Peptide Research Lab, in Belgium, reviewed the evidence about the body clock’s role in weight maintenance.

Chronobesity: role of the circadian system in the obesity epidemic.

What is the Body Clock?

The body clock is a biological rhythm present in almost all living things.

It regulates the 24-hour fluctuations in body activity, including hormones and other metabolic processes. It also helps the body prepare for sleep/wakefulness or food.

At the molecular level, the circadian system is driven by CLOCK genes, which are influenced by environmental information passed on by the brain and neurons (12).

A region in the brain, known as the suprachiasmatic nucleus (SCN), is often called the body’s master pacemaker because it is synchronized with the light/dark cycle.

The food-entrainable oscillator also appears to be involved with the circadian rhythm of feeding, but its rhythm is closely related to the SCN (34).

Interestingly, the activity and composition of the gut bacteria also changes over the 24-hour day, and is influenced by food intake (56).

Bottom Line: The body clock is the body’s timekeeping system that helps it prepare for sleep and wakefulness. This system is strongly affected by light exposure and food intake.

How Does the Body Clock Affect Weight?

The body clock helps the body anticipate and prepare for food intake.

Under natural conditions, food intake is influenced by food availability, hunger and appetite. Hunger and appetite are also strongly influenced by appetite hormones.

These hormones are regulated by the circadian system of feeding, which helps ensure that people maintain their weight, even when food availability is limited.

The circadian system also mediates food intake over the 24-hour day, suppressing appetite during the night, and increasing appetite during the day.

These fluctuations in appetite are reflected by the daily changes in the levels of the hunger hormone ghrelin. In healthy individuals, ghrelin levels are suppressed at night, but rise in the morning, peaking before meal time (789).

Bottom Line: The body clock controls changes in appetite over the 24-hour day. It is supposed to restrict food intake to waking hours, while at the same time ensuring that calorie intake is sufficient for weight maintenance.

Body Clock Disruption Promotes Weight Gain

Disrupting the body clock has been called chronodisruption, and is defined as a long-term disruption of the 24-hour circadian rhythm (10).

Several factors can cause a long-term disruption, including irregular sleeping, abnormal eating and a high-fat diet.

Abnormal Sleeping Patterns

Irregular sleeping is one of the most common disruptions to the circadian system. It is most often caused by shift work, frequent travelling across time zones or other nighttime disturbances.

During travel, this is called jet lag. Symptoms include poor sleep, poor mental and physical performance, fatigue, headache, irritability, indigestion and diarrhea (11).

Shift work often involves working during the night, or late into the night. Light exposure at night is one of the most important disruptions to the circadian system.

Several observational studies suggest shift work may increase the risk of various chronic diseases, such as obesity, type 2 diabetes and heart disease. This risk may also worsen over time (12131415).

One study in healthy people examined the effects of shifting the sleeping time. When eating and sleeping times were 12 hours out of phase with what the participants were used to, levels of the satiety hormone leptin decreased (16).

Although disrupting appetite hormones seems to be involved, it remains to be explained exactly how irregular sleeping affects body weight.

Bottom Line: Irregular or abnormal sleeping patterns mess up the body’s timekeeping. Common causes include shift work and jet lag. This disruption may promote obesity, but human trials are lacking.

Irregular Eating Patterns

Body weight is not only affected by what and how much you eat — it is also affected by when you eat. Irregular eating can be caused by numerous factors, including disruptions to sleep caused by shift work, jet lag or nighttime sleep disturbances.

It may also be caused by adverse conditions, such as night-eating syndrome, which is associated with abnormal fluctuations in the levels of appetite hormones.

People who have night-eating syndrome consume most of their daily calories in the evening or night. They are also more likely to be overweight or obese, compared to healthy people (817).

This is supported by studies in mice and rats showing that nighttime eating causes significant weight gain, compared to daytime eating (1819).

Irregular eating has also been found to cause adverse changes in the gut microbiota.

One high-impact study in both mice and humans showed that eating irregularly promoted an overgrowth of undesirable gut bacteria, increasing the risk of type 2 diabetes and obesity (5).

Bottom Line: Irregular eating may also disrupt the body clock. This may lead to weight gain, especially when food intake is significant in the late evening or night.

Consuming a High-Fat Diet

A few studies indicate that a high-fat diet may also disrupt the body clock. One study in women showed that a high-fat diet reduced the average 24-hour levels of the satiety hormone leptin (20).

Another study in mice found that following a high-fat diet for a week led to increased food intake when the mice were normally resting. This was accompanied by changes in the expression of CLOCK genes (21).

Obesity caused by excessive calorie intake on a high-fat diet may also reduce the 24-hour fluctuations in the composition of the gut microbiota, resulting in the overgrowth of undesirable bacteria (22).

Bottom Line: High-fat diets have been implicated in the disruption of the body clock. However, further studies are needed.

Summary and Real-Life Application

This review showed that disrupting the body clock may contribute to weight gain and obesity. However, it also discussed some evidence-based strategies that may help you maintain healthy rhythms and reduce this risk.

  • Eat plenty of protein during the first meal of the day (2324).
  • Eat lunch at noon and do not postpone it until later (25).
  • Include plenty of carbs in the last meal of the day (2627).
  • Make sure that your last meal of the day is the lightest (28).
  • Avoid eating late and eat dinner at least 3 hours before bedtime (26).
  • Avoid eating too much fat (20).
  • Try to get high-quality sleep (2930).
  • Exercise regularly to burn calories and improve sleep (31).
  • Keep your sleeping patterns regular (32).
  • Do not work during the night.
  • Block out blue light from electronic screens during the late evening (3334).
  • Try to avoid frequent travelling across time zones.

The Mineral Phosphorus May Help You Lose Weight

Observational studies suggest that people who eat more phosphorus gain less weight.

However, the effects of phosphorus supplementation on weight loss have never been studied in humans.

For this reason, a team of scientists recently conducted a study. Below is a detailed summary of their results, published in Nutrition & Diabetes.

Background

Phosphorus is a dietary mineral that is essential for every cell in the body.

Most of it is found in your bones and teeth. In plants and animals, phosphorus is bound to oxygen, forming phosphate.

Phosphate is found in most food in varying amounts, but the best dietary sources are dairy products, meat and fish (1).

Even though cereals and legumes are also rich sources of phosphorus, most of it is found in the form of phytate or phytic acid, which is poorly absorbed (2).

Interestingly, scientists have speculated that poor phosphorus status may increase the risk of weight gain and obesity.

This claim is supported by observational studies associating low phosphorus status with increased body weight (345).

However, human trials are needed to confirm these findings.

Article Reviewed

A group of researchers from Beirut, Lebanon, conducted a study examining the effects of phosphorus supplementation on body weight.

Effect of phosphorus supplementation on weight gain and waist circumference of overweight/obese adults: a randomized clinical trial.

Study Design

This was a double-blind, randomized controlled trial in overweight, but otherwise healthy, adults aged 18–45 years.

The participants were randomly assigned to one of two groups:

  • Phosphorus group: Participants took phosphorus supplements with a meal 3 times a day for 12 weeks, amounting to 1,125 mg per day.
  • Placebo group: Participants took the same amount of a placebo.

At the beginning, middle and end of the study, the researchers measured body weight, waist circumference, subjective appetite scores, and fasting levels of phosphorus, creatinineC-reactive protein, blood lipids, blood sugar and insulin.

A total of 47 participants completed the study, or 75% of those who were recruited.

Bottom Line: This was a 12-week, randomized controlled trial examining the effects of a phosphorus supplement on body weight and appetite.

Finding 1: Phosphorus Caused Weight Loss and a Reduction in Waist Circumference

At the end of the study, those in the phosphorus group had lower body weight, body mass index and waist circumference, compared to the placebo group, as shown in the chart below.

Phosphorus and Placebo on Weight Factors
In the phosphorus group, body weight decreased by 0.65 kg (1.4 lbs), whereas body weight increased by 1.13 kg (2.5 lbs) in the placebo group.

These results are supported by observational studies suggesting that a poor phosphorus status may predispose people to weight gain (678).

As a possible explanation, a few human trials suggest that phosphorus intake may reduce appetite at a subsequent meal or increase metabolic rate (9101112).

However, note that the present study is the first human trial to examine the effects of phosphorus on body weight. Further studies are needed to confirm its results.

Bottom Line: Supplementing with phosphorus caused weight loss and a reduction in waist circumference. These results need to be confirmed by further studies.

Finding 2: Phosphorus Reduced Appetite

In the phosphorus group, subjective ratings of appetite decreased.

These included appetite, the amount of food needed to reach fullness and the number of snacks eaten.

The findings are supported by one study in which phosphorus intake reduced food intake at a subsequent meal (9).

Bottom Line: Supplementing with phosphorus reduced subjective ratings of appetite.

Finding 3: Blood Levels of Phosphorus Did Not Increase

Levels of phosphorus in blood plasma did not increase among those participants who got phosphorus supplements.

This indicates that plasma phosphorus levels are not a good indicator of phosphorus intake, as confirmed by previous studies (1314).

Bottom Line: The study suggests that phosphorus intake is not reflected in increased fasting levels of phosphorus in blood, supporting earlier findings.

Limitations

The study had no obvious major limitations.

However, the methods section of the article lacks information. For example, there is no information on the type of phosphorus/phosphate supplement used.

Additionally, phosphorus levels in blood plasma did not increase in people who got phosphorus supplements.

While this is supported by previous studies suggesting phosphorus levels in blood do not reflect intake, it also means the researchers were unable to test compliance.

Bottom Line: This study had no apparent limitations, but the paper is lacking information on the supplement that was used.

Summary and Real-Life Application

In short, this study showed that phosphorus supplements may promote weight loss.

They do this, most likely, by suppressing appetite and calorie intake.

Since this is the first study to show that phosphorus reduces body weight, further studies are needed to confirm its findings.

Eating Less May Prevent Disease and Help You Live Longer

In many animal species, such as monkeys, eating less has been linked to longer lifespans. However, this is much harder to measure in humans, since we live longer.

Therefore, a team of scientists decided to study how reducing calorie intake affects predictors of longevity. Their results were published in Journals of Gerontology: Medical Sciences.

Background

Calorie restriction refers to a diet that does not contain enough calories to maintain weight. Over time, this leads to significant weight loss or starvation, if the calorie restriction is severe.

However, during moderate calorie restriction, weight loss gradually slows down. This is known as the starvation response, or metabolic adaptation, and is characterized by a reduced metabolic rate.

Moderately restricting calories may have many health benefits, especially if you keep it up for a long time and get enough essential nutrients.

In many animals, such as rhesus monkeys, moderate calorie restriction increases lifespan and slows down the development of many age-related diseases (123).

This is supported by observational studies in humans indicating that long-term calorie restriction may improve many risk factors of chronic disease (4).

Randomized, controlled trials have also shown that when overweight people follow a reduced-calorie diet for 6–12 months, many risk factors are improved (567).

Study Reviewed

A team of researchers examined the effects of moderate calorie restriction on predictors of longevity in normal-weight adults.

A 2-Year Randomized Controlled Trial of Human Caloric Restriction: Feasibility and Effects on Predictors of Health Span and Longevity.

Basic Study Design

This randomized, controlled trial studied the feasibility and safety of long-term, moderate calorie restriction. It also examined its effects on predictors for longevity.

To date, this is the largest study to examine the effects of long-term calorie restriction in adults. Non-obese men and women, aged 21–51 years, participated in the study for 2 years.

The participants were randomly assigned to one of two groups:

  • Calorie restriction: Participants in this group cut their daily calorie intake by 25%, designed to cause a 15.5% weight loss over 2 years.
  • Control: In this group, the participants changed none of their dietary habits.

At regular intervals during the study, the researchers measured several factors, including the change in resting metabolic rate, blood levels of triiodothyronine (T3) and tumor necrosis factor-α (TNF-α).

A total of 188 people completed the study, or 86% of those who started.

Bottom Line: This was a randomized, controlled trial examining the effects of sustained calorie restriction on predictors of longevity.

Finding 1. Calorie Restriction Slowed Metabolism

Metabolic rate is a measure of metabolism that estimates the amount of calories used by the body at a given time. In animals, a low resting metabolic rate (RMR) has been associated with increased life span (89).

In the present study, resting metabolic rate decreased significantly more in those who were on a reduced-calorie diet.

This difference in RMR across groups was mostly explained by the greater weight loss among those who were on a reduced-calorie diet.

However, starvation response was also responsible for some of it. Starvation response was estimated as the difference between measured and predicted RMR.

In the first year of the study, the participants lost 10% of their initial body weight, on average. But because of metabolic slowdown, body weight stabilized in the second year of the study.

Bottom Line: Sustained calorie reduction led to slower metabolism or a decreased resting metabolic rate (RMR). This was caused by weight loss as well as the starvation response.

Finding 2. Calorie Restriction Reduced Triiodothyronine (T3)

Triiodothyronine (T3) is a thyroid hormone that affects metabolism, body temperature and heart rate. Low thyroid activity has been associated with longevity in animals (10).

The present study showed that T3 decreased by more than 20% in those who were on a reduced-calorie diet, as shown in the chart below.

Bottom Line: Levels of the thyroid hormone triiodothyronine (T3) decreased significantly on the reduced-calorie diet. Reduced T3 has been associated with longevity in animal studies.

Finding 3. Calorie Restriction Lowered TNF-α

Tumor necrosis factor alpha (TNF-α) is an inflammatory marker. High levels of TNF-α indicate systemic inflammation, and in animal studies, low levels of TNF-α have been associated with longevity (11).

In the present study, levels of TNF-α decreased significantly in those who were on a reduced-calorie diet, as shown in the chart below.

These findings are consistent with observational studies showing lower TNF-α in people who have been on a reduced-calorie diet for a long time (12).

Bottom Line: Calorie restriction caused a significant decrease in the inflammatory marker TNF-α, suggesting reduced systemic inflammation. Reduced TNF-α has been associated with longevity in animals.

Finding 4: Calorie Restriction Improved Heart Disease Risk Factors

Reducing calories also favorably affected many risk factors for heart disease, including:

  • Significant weight loss: The reduced-calorie diet led to a 10% reduction in body weight during the first year of the study, which was maintained in the second year.
  • Improved blood lipids: Levels of triglycerides, LDL-cholesterol and total cholesterol decreased.
  • Lower blood pressure: Systolic and diastolic blood pressure dropped.
  • Better blood sugar control: Insulin sensitivity improved.

Bottom Line: Calorie restriction led to significant weight loss, an improved blood lipid profile, lower blood pressure and better blood sugar control.

Potential Adverse Events

For most of the participants, moderately reducing calories did not appear to have any serious adverse effects. However, a few of the participants were withdrawn from the study due to health problems.

These included a decrease in bone mineral density, and anemia that didn’t improve with treatment. Additionally, one participant lost too much weight.

Overall, bone mineral density was significantly reduced in the calorie-restricted group, compared to the control group. However, these decreases were small.

This suggests that sustained calorie restriction may, over many years or decades, lead to osteoporosis and fractures.

However, it is unclear whether this is caused by calorie restriction itself or an insufficient intake of certain nutrients.

Bottom Line: Moderate calorie restriction is generally safe for most healthy people, as long as the intake of essential nutrients is sufficient. However, this may depend on the individual.

Limitations

This study appears to have been designed and implemented well, with no apparent limitations.

During the study, however, the calorie-restricted group only lost 10% of their initial body weight, not the expected 15.5%.

This is because the participants did not achieve the planned 25% calorie restriction, but only about 12%. Why this happened is unclear, but it might have been due to lack of compliance and/or an inaccurate study design.

Also, the study’s findings are limited to highly motivated, healthy, non-obese individuals. Sustained calorie restriction may have different effects in other groups.

Bottom Line: The study was planned and implemented well. However, participants did not achieve the planned 25% calorie restriction.

Summary and Real-Life Application

In short, the study showed that moderate, long-term calorie restriction is both feasible and safe for healthy, non-obese people.

Although the effects on life span couldn’t be measured directly, a reduced-calorie diet improved several health aspects related to longevity.

Simply put, moderately reducing calories may have many potential benefits, as long as the intake of essential nutrients is adequate.

In some cases, however, reducing calories can be downright harmful. If you are not overweight, consult with your doctor before going on a reduced-calorie diet.

The DASH Diet Lowers Blood Pressure, Even With More Fat

The DASH diet is designed to reduce blood pressure and improve blood lipids.

It’s typically low in fat and relatively high in carbs, but it’s not clear what role these macronutrients play in the diet’s effectiveness.

For this reason, a group of researchers compared the effects of a higher-fat, lower-carb DASH diet to the conventional DASH diet.

Their results were recently published in the American Journal of Clinical Nutrition.

Background

DASH stands for Dietary Approaches to Stop Hypertension.

It is currently the world’s most popular diet aimed at lowering blood pressure and reducing the risk of heart disease.

The original DASH diet has the following characteristics (12):

  • High in fruits and vegetables.
  • High in whole grains and fiber.
  • Includes nuts, seeds and legumes several times weekly.
  • High in low-fat dairy products.
  • Relatively low in red meat, poultry and fish.
  • Low in saturated fat, cholesterol and sodium.
  • Relatively high in potassium, magnesium and calcium.
  • Relatively low in refined sugar.

A large, observational study, called the Nurses’ Health Study, found a DASH-type diet to be associated with a reduced risk of heart disease and stroke (3).

Some researchers believe that the DASH diet may reduce heart disease risk because of its low saturated fat content (45).

However, this idea has not been put to the test.

Article Reviewed

A team of scientists from the Children’s Hospital Oakland Research Institute, in California, compared the effects of the standard DASH diet and a higher-fat, lower-carb DASH diet on blood pressure and blood lipids.

Comparison of the DASH (Dietary Approaches to Stop Hypertension) diet and a higher-fat DASH diet on blood pressure and lipids and lipoproteins: a randomized controlled trial.

Basic Study Design

This randomized, controlled trial examined the effects of a modified DASH diet and the standard DASH diet on blood pressure and blood lipids. The modified diet included more dairy fat and fewer carbs.

The participants were healthy men and women with systolic blood pressure less than 160 mm Hg, and diastolic blood pressure between 80 and 95 mm Hg.

The participants were assigned to three groups in random order:

  • Standard DASH diet: Participants followed the conventional DASH diet.
  • Higher-fat DASH diet: This diet included more dairy fat and less carbs, but was otherwise identical to the standard DASH diet.
  • Control diet: The control diet was designed to represent a normal Western diet.

In the higher-fat DASH diet, the saturated fat content was increased from 8% to 14% of daily calories. To keep the calorie content the same, the carb content was also reduced by 12% of daily calories.

Each of these diets lasted for 3 weeks. The study had a crossover design, meaning that all of the participants followed all three diets during different study periods, separated by a 2-week washout period.

At the beginning and end of each of the three diets, the researchers measured blood pressure, blood lipids, body weight and body fat.

A total of 36 participants completed the study.

Bottom Line: This randomized, crossover trial examined the effects of a higher-fat, lower-carb DASH diet on blood pressure and blood lipids.

Finding 1: Dairy Fat Did Not Adversely Affect Blood Pressure

Both the standard DASH diet and the higher-fat DASH diet reduced blood pressure to a similar extent, compared to the control diet, as shown in the chart below.

DASH  Diets and Control Blood Pressure

However, blood pressure was significantly lower two weeks after the participants had finished the higher-fat DASH diet, suggesting delayed effects.

This means that eating more saturated dairy fat on the DASH diet does not adversely affect blood pressure.

Other studies have found that modifying the standard DASH diet by replacing carbs with unsaturated fat or protein yields similar or greater improvements in blood pressure (678).

Bottom Line: The standard DASH diet and the higher-fat DASH diet reduced blood pressure to a similar extent, compared to the control diet.

Finding 2: Higher-Fat DASH Diet Reduced Triglycerides

The DASH diet and the higher-fat DASH diet had different effects on the blood lipid profile. The higher-fat DASH diet reduced the levels of triglycerides, as shown in the chart below.

DASH Diets and Control Triglycerides

This modest reduction in triglycerides may be explained by the lower amounts of carbs in the higher-fat DASH diet, compared to the standard DASH diet (9).

Bottom Line: The higher-fat DASH diet reduced triglycerides, compared to the standard DASH diet, due to the lower carb content of the higher-fat diet.

Finding 3: Effects on LDL Peak Diameter

High levels of small, low-density lipoproteins (LDL) have been associated with an increased risk of heart disease (10).

In the present study, the conventional DASH diet reduced the peak diameter of the LDL particles, but the higher-fat DASH diet increased the peak diameter, compared to the control diet.

This means that the higher-fat DASH diet may have caused a modest increase in LDL particle size.

In fact, there was a trend for higher levels of large LDL particles with the higher-fat DASH diet, but the findings were not significant.

Previous studies have shown that reduced carb and sugar intake may cause a shift from smaller to larger LDL particles, explaining the present findings (1112).

Bottom Line: The higher-fat DASH diet increased LDL peak diameter, whereas the standard DASH reduced the LDL peak diameter. Large LDL size has been associated with a reduced risk of heart disease.

Finding 4: No Increase in LDL-Cholesterol

The higher-fat DASH diet did not increase levels of LDL-cholesterol, compared to the standard DASH diet.

This is inconsistent with studies showing that replacing carbs or unsaturated fats with saturated fats increases LDL-cholesterol (913).

The authors speculate that the DASH diet may have characteristics that prevent the rise in LDL-cholesterol typically associated with a higher intake of saturated fats.

Bottom Line: The higher-fat DASH diet did not increase LDL-cholesterol, compared to the standard DASH.

Limitations

This study appears to have been designed and implemented well.

It was a crossover trial, meaning that all participants were on all three diets during different study periods, separated by a 2-week washout period.

The purpose of the washout period was to prevent the previous diet from affecting the results of the next diet.

This washout, however, doesn’t appear to have worked in all cases, since there were some prolonged effects of the higher-fat DASH diet on blood pressure. The reason for this is unexplained.

Other limitations include a small number of participants and a relatively short study period.

Bottom Line: This study did not have any serious limitations. However, the 2-week washout period between diets may not have been long enough with respect to blood pressure.

Summary and Real-Life Application

In short, this study shows that eating slightly more saturated dairy fat while on the DASH diet does not affect its beneficial effects on blood pressure.

Also, it did not have any adverse effects on the blood lipid profile.

A lower-carb, higher-fat DASH diet is a healthy, equally effective option, which may be easier to follow than the standard DASH diet.

Isolated Trans Fats are Unhealthy, Regardless of the Source

Industrially produced trans fats are known to be bad for heart health. Yet the effects of natural trans fats, found in dairy products and meat, are less clear.

For this reason, a team of scientists compared the effects of these two groups of trans fats on the blood lipid profile.

Below is a detailed overview of their results, recently published in the American Journal of Clinical Nutrition.

Background

Trans fats are a type of dietary fat mainly found in processed food products containing partially hydrogenated oil.

These include foods such as margarine, shortening, deep-fried food, microwave popcorn, and store-bought cookies and cakes.

However, trans fats are also naturally present in smaller amounts in body or milk fat from ruminant animals like cows, sheep and goats.

Many studies suggest that a high intake of industrially produced trans fats may increase the risk of heart disease, and limiting intake is recommended (1).

However, the health benefits of natural trans fats are less clear. One type, conjugated linoleic acid, may even have health benefits.

Nonetheless, observational studies in humans have provided inconsistent results about the health effects of natural trans fats in general (12345).

Human trials are few and have not been able to provide strong evidence, due to shortfalls in their design (678910).

Article Reviewed

A group of researchers examined the difference between industrially produced and natural trans fats on the blood lipid profile.

Vaccenic acid and trans fatty acid isomers from partially hydrogenated oil both adversely affect LDL cholesterol: a double-blind, randomized controlled trial.

Basic Study Design

This was a double-blind, randomized, controlled trial comparing the effects of synthetic and natural trans fatty acids on blood lipids.

Healthy men and women, aged 25 to 65 years, participated in the study. Most of them were middle-aged, overweight or obese, and at a potential risk for heart disease.

The participants were assigned to four diets in a random order:

  • Vaccenic acid (VA): 3.3% of calories were from vaccenic acid, the most common natural trans fat.
  • Industrially produced trans fats (iTF): 3.3% of calories were from a mixture of industrially produced trans fats from partially hydrogenated vegetable oil.
  • Conjugated linoleic acid (CLA): 0.9% of calories were from conjugated linoleic acid (c9,t11-CLA), a natural trans fat associated with health benefits.
  • Control diet: 0.1% of calories were from mixed trans fats, both naturally and industrially produced.

Each diet lasted for 24 days and was completely controlled. All the diets had the same macronutrient composition: 34% of calories from fat, 50% from carbs and 17% from protein.

The additional calories from trans fats replaced calories from stearic acid, a common fatty acid that has neutral effects on both LDL-cholesterol and HDL-cholesterol.

The study had a crossover design, meaning that each participant was in each of the groups on different occasions. At the start and end of each of the diets, the researchers measured blood lipids, inflammatory markers and body weight.

A total of 116 participants started the study, and 91% completed at least one of the four study periods.

Bottom Line: This randomized, controlled trial compared the effects of industrially produced trans fats and natural trans fats on blood lipids.

Finding 1: All Trans Fats Increased Total Cholesterol

High levels of cholesterol in the blood may increase the risk of heart disease.

In the current study, both the iTF and the VA diets increased total cholesterol, compared to the control diet. However, the VA diet increased cholesterol even more.

Chart 1 Trans Fats Total Cholesterol

Therefore, it can be concluded that trans fats increase cholesterol, regardless of their source. One exception is conjugated linoleic acid (CLA), which did not affect total cholesterol.

Bottom Line: Regardless of their dietary source, trans fats increased total cholesterol. Natural trans fats in the VA diet, however, increased cholesterol more. CLA, additionally, had neutral effects.

Finding 2: Natural Trans Fat Increased LDL-Cholesterol and Apolipoprotein B

When levels of cholesterol become too high, it is often because of increased concentration of low-density lipoproteins (LDL).

Cholesterol carried around in LDL (LDL-cholesterol) is considered especially unhealthy when its levels are abnormally high.

In the present study, LDL-cholesterol increased during both the iTF and the VA diets, compared to the control. The rise in LDL-cholesterol, however, was significantly higher during the VA diet, as shown in the chart below.

Chart 2 Trans Fats on LDL Cholesterol

These results are supported by a previous study showing that a diet high in vaccenic acid increased LDL-cholesterol (8).

Apolipoprotein B

Apolipoprotein B (apoB) is a class of proteins found on the surface of low-density lipoproteins (LDL). High levels are associated with an increased risk of heart disease.

In the current study, both the VA and the iTF diets increased levels of apoB, compared to the control. However, apoB increased more during the VA diet, as shown in the chart below.

Chart 5 Trans Fats on ApoB

Bottom Line: Both types of trans fats raised levels of LDL-cholesterol and apoB, but VA caused larger increases to both.

Finding 3: Natural Trans Fat Increased HDL-Cholesterol and Apolipoprotein A1

High levels of high-density lipoproteins (HDL-cholesterol) are considered beneficial for heart health.

Although this is supported by many observational studies, the benefits of raising HDL-cholesterol have not been confirmed in clinical trials (11).

In the present study, HDL-cholesterol increased during the VA diet. In comparison, the iTF diet had no effects.

Both the VA diet and the iTF diet increased the ratio of total cholesterol and HDL-cholesterol similarly. The same applied to the ratio of LDL-cholesterol and HDL-cholesterol.

Apolipoprotein A1

Apolipoprotein A1 (apoA1) is a class of proteins mainly found on the surface of high-density lipoproteins (HDL).

As with HDLs, high levels of apoA1 have been associated with a reduced risk of heart disease. In the present study, apoA1 increased during the VA diet, but not the iTF diet.

Chart 6 Trans Fats ApoA1

Bottom Line: Naturally occurring vaccenic acid increased levels of HDL-cholesterol and decreased levels of apoA1, while the industrially produced trans fats did not affect either.

Finding 4: Natural Trans Fat Increased Triglycerides

Triglycerides are a type of fat that circulate in the blood.

As with cholesterol, abnormally high levels of triglycerides have been associated with an increased risk of heart disease.

In the current study, the levels of triglycerides rose higher during the VA diet, compared to the iTF diet.

In contrast, CLA lowered triglyceride levels, compared to the control.

Bottom Line: Vaccenic acid increased triglycerides more than industrially produced trans fats.

Finding 5: Natural Trans Fat Decreased Fibrinogen

Fibrinogen is a type of protein that helps the blood clot. As a result, high levels of fibrinogen are associated with an increased risk of heart disease (1213).

In the present study, the VA diet lowered fibrinogen, compared to iTF and the control diet.

High levels of fibrinogen have been associated with systemic inflammation. In this study, however, levels of inflammatory markers remained unchanged across diets.

Bottom Line: Levels of fibrinogen decreased when the participants were on a diet high in vaccenic acid. Industrially produced trans fats had no effects.

Limitations

This study did not appear to have any serious limitations, but a few issues should be mentioned.

First, the VA and iTF diets were supposed to provide the same amount of calories from trans fat. However, these two diets actually differed by 0.67%.

The VA diet provided 3.86% of calories from vaccenic acid, whereas the iTF diet provided 3.26% of calories from industrially produced trans fats. These differences might have affected the results.

Second, the study tested much higher amounts of trans fat than are normally consumed in the USA.

Certain subgroups of people may reach similar intake levels for industrially produced trans fats. The amount of vaccenic acid used, however, exceeded normal dietary intakes by far.

Finally, the dietary context may play a role. In this study, the researchers used synthetic vaccenic acid that was not consumed with dairy fat or meat.

Previous studies suggest that vaccenic acid does not affect the risk of heart disease when eaten in normal amounts with milk or meat (141516).

Bottom Line: The study did not have any important limitations.
However, the VA diet provided a greater proportion of calories from trans fat, compared to the iTF diet.

Summary and Real-Life Application

In short, this study shows that both industrially produced trans fats and vaccenic acid, the most common natural trans fat, adversely affect the blood lipid profile, when consumed in equal amounts.

However, this does not mean that natural foods containing natural trans fats need to be avoided. Studies indicate that when eaten in normal amounts with milk or meat, vaccenic acid does not impair heart health (141516).

Also, natural trans fats include conjugated linoleic acid (CLA), which may have health benefits.

For optimal health, it is more important to limit the intake of industrially produced trans fats from processed food.

Chitosan Supplements May Cause Weight Loss

Chitosan is a dietary fiber sold as a weight loss supplement. However, studies have provided inconsistent results about its effectiveness.

Recently, a team of researchers from India evaluated the effects of one weight loss supplement containing chitosan.

Below is a detailed summary of their findings, published in Nutrition Journal.

Background

Chitosan is a synthetic dietary fiber made from chitin, which comes from the shells of crustaceans. It is also found in the cell walls of fungi (1).

Chitosan has special properties that bind with fat, decreasing fat absorption. For this reason, taking chitosan with meals may reduce the overall calorie content. Chitosan may also reduce blood cholesterol levels (2345).

Several studies have evaluated the effects of chitosan on body weight. Here are their findings from over the years:

  • 1999: 2,000 mg of chitosan a day, for 28 days, had no significant effects (6).
  • 2001: 3,000 mg of chitosan a day, for 12 weeks, had no significant effects (7).
  • 2004: This review found chitosan’s effects on body weight to be minimal, and unlikely to be clinically relevant (8).
  • 2006: Along with a behavior modification program, 3,000 mg of chitosan each day, for 60 days, caused significant weight loss of 2.8 lbs (1.3 kg) (9).
  • 2008: Chitosan may have some minimal, short-term benefits, but is unlikely to have any clinically relevant effects (10).
  • 2008: Along with exercise, 2,000 mg of chitosan (polyglucosamine) a day, for 4 months, led to an additional 8.6 lbs (3.9 kg) of weight loss (11).
  • 2015: Along with diet and exercise, 1,700 mg of chitosan (polyglucosamine) a day, for 24 weeks, caused an additional 3.9 lbs (1.8 kg) of weight loss (12).

In short, most of the evidence suggests that 1,700–3,000 mg of chitosan per day may help reduce body weight over the course of several months.

However, chitosan does not seem to work any miracles on its own. It needs to be used with other weight loss strategies, such as diet or exercise.

Article Reviewed

A group of Indian researchers examined the effectiveness of 2,500 mg of chitosan on body weight in overweight and obese men and women.

Single-blind, placebo controlled randomised clinical study of chitosan for body weight reduction.

Basic Study Design

This was a 90-day, single-blind, randomized controlled trial examining the effectiveness of chitosan for weight loss.

It was a phase IV trial, testing the safety and effectiveness of a patented weight loss supplement, KiOnutrime-CsG®, produced by KitoZyme.

A total of 96 overweight or obese men and women, aged 18 to 65 years, started the study. They were unevenly randomized, in the ratio of 2:1, into one of two groups:

  • Chitosan: 64 participants took chitosan capsules before breakfast, lunch and dinner, totaling 2,500 mg per day.
  • Placebo: 32 participants took the same amount of placebo capsules, containing a cellulose powder.

The chitosan was of fungal origin and was taken 15 minutes before meals. Previous research suggests that it may take some time for chitosan to dissolve in the digestive system before becoming usable (4).

At the start, middle and end of the study, the researchers measured body weight, body composition, the blood lipid profile and glycated hemoglobin (HbA1c).

A total of 86 participants completed the study, or 90% of those who initially started.

Bottom Line: This was a randomized controlled trial examining the effectiveness of the weight loss supplement chitosan.

Finding 1: Chitosan Led to Weight Loss

Supplementing with chitosan led to significantly more weight loss than the placebo.

In fact, those who took chitosan lost 2.2 lbs (1.0 kg) each month, on average. This amounted to 6.8 lbs (3.1 kg) over the 3-month study period.

In comparison, the placebo group did not experience significant weight loss.

This weight loss in the supplement group was caused by loss of fat mass and lean mass, as shown in the chart below.

Chitosan and Placebo Changes in Mass

Similarly, waist and hip circumference decreased among the participants in the supplement group.

These findings are interesting, because the participants did not go on a diet or increase their physical activity. The chitosan, on its own, had significant benefits.

Previous trials do not support these results. Without other weight loss strategies, chitosan supplements have not lead to significant weight loss (67).

However, chitosan may be effective when participants are also making dietary, exercise or behavior modifications (91112).

Bottom Line: Supplementing with chitosan led to significant weight loss without any dietary restrictions or increased exercise.

Finding 2: Chitosan Improved Blood Sugar Control

HbA1c is also known as glycated hemoglobin. It is measured to evaluate the average blood sugar levels of the past few weeks.

In the present study, supplementing with chitosan led to a reduction of HbA1c levels in participants who had high levels (over 6%) initially.

These results are supported by a previous study showing that chitosan may reduce blood sugar after meals in humans (13).

Bottom Line: Chitosan reduced the levels of HbA1c. These findings suggest that chitosan may improve blood sugar control.

Finding 3: Chitosan Did Not Affect Blood Lipids

The researchers measured several different blood lipids at the start, middle and end of the study. These included triglycerides, HDL, LDL and VLDL.

None of these blood lipids changed significantly during the study period.

These findings are inconsistent with previous studies showing that chitosan may have significant positive effects on the blood lipid profile (1415).

Bottom Line: Supplementing with chitosan had no significant effects on the blood lipid profile.

Limitations

This study had several potential limitations.

First, it was conducted by Ethicare Clinical Trial Services, which specializes in conducting clinical research for pharmaceutical companies. As a result, competing interests may have been involved.

Additionally, two of the paper’s authors were employees of KitoZyme, the company that produces the weight loss supplement. This is a clear conflict of interest.

Second, the researchers were not blinded. This probably didn’t affect the results, but does create the potential for bias (1617).

Third, the researchers also assessed body composition using bioelectrical impedance analysis (BIA), which can be inaccurate (18).

Finally, the supplement assignment was unequal, as there were twice as many participants receiving chitosan than the control. The researchers do not clearly explain why they did this (19).

Bottom Line: The researchers had potential competing interests. There were also some minor limitations to the research methods and study design.

Summary and Real-Life Application

This study showed that chitosan supplements may lead to significant weight loss over time, without dietary changes or increased exercise.

However, these results may depend on the form of chitosan or the way it’s produced. The study only examined KiOnutrime-CsG®, a formula developed by KitoZyme.

Additionally, two of the paper’s authors were employees of KitoZyme, and the study was done by a company that’s funded by the pharmaceutical industry.

Therefore, these findings need to be confirmed by an independent research team.

Very High Amounts of Fat May Reduce Insulin Sensitivity

Studies show that calorie-reduced diets improve insulin sensitivity, regardless of their fat content (123).

However, it’s unclear if this is due to the composition of the diet or weight loss.

For this reason, a group of scientists compared the effects of high- and low-fat diets, while maintaining stable weight.

Below is a review of their findings, published in the European Journal of Nutrition.

Background

Insulin sensitivity refers to how sensitive the body is to the effects of insulin.

Low insulin sensitivity, also known as insulin resistance, means the body doesn’t respond to insulin efficiently. This adverse condition characterizes type 2 diabetes and can lead to abnormally high blood sugar after meals.

It’s unclear exactly what causes insulin resistance, but several studies have examined how diet composition affects insulin sensitivity.

Two short-term studies compared the effects of diets high in fat (50–55% of calories) and low in fat (20–25% of calories) on insulin sensitivity. They found no significant differences in insulin sensitivity between diets (45).

Another study in older individuals showed that a 4-week, high-fat diet (42% of calories), high in saturated fat (24% of calories), did not cause significant changes in insulin sensitivity (6).

What’s more, an 11-day study found that a very-high-fat diet (83% of calories) had no effects on insulin sensitivity, compared to a diet that contained no fat (7).

However, the evidence is not entirely conclusive. Some studies indicate that low-fat diets may improve insulin sensitivity (68).

In short, it seems that eating high amounts of fat does not increase your risk of becoming insulin resistant, but more research is needed.

Article Reviewed

Researchers from the University of Washington in the US compared the effects of a very high-fat diet and a low-fat diet on insulin sensitivity.

A high‑fat, high‑saturated fat diet decreases insulin sensitivity without changing intra‑abdominal fat in weight‑stable overweight and obese adults.

Study Design

The main purpose of this small, randomized, controlled trial was to examine the effects of a high-fat diet, rich in saturated fat, on insulin sensitivity.

The study included 13 overweight or obese men and women, aged 18–55 years.

For the first 10 days of the study, all of the participants followed a standardized diet. It provided 47% of calories from carbs, 18% from protein, and 35% from fat, including 12% from saturated fat.

Then, the participants were assigned to two 4-week diets in a random order:

  • Low-fat diet: 20% of calories from fat, including 8% from saturated fat, 62% from carbs and 18% from protein.
  • High-fat diet: 55% of calories from fat, including 25% from saturated fat, 27% from carbs and 18% from protein.

These two diets were identical, apart from their varying fat and carb content. The major sources of fat in both diets were butter and safflower oil, high in oleic acid.

The study kitchen provided participants with all food, and they were weighed twice weekly to ensure weight stability.

The study had a crossover design, meaning that the participants followed both diets on different study periods, separated by 6 weeks.

At the beginning and end of the diets, the researchers measured insulin sensitivity, abdominal fat and fasting levels of very-low-density lipoproteins (VLDLs).

Only 7 participants completed both diets, or 54% of those who originally started.

Bottom Line: This was a randomized, crossover trial comparing the effects of a very high-fat diet and a low-fat diet on insulin sensitivity.

Finding 1: A High-Fat Diet Reduced Insulin Sensitivity

Insulin sensitivity is often assessed by injecting people with insulin and then measuring blood sugar clearance, or how quickly blood sugar levels drop.

During the high-fat diet, insulin sensitivity decreased, whereas it remained constant during the low-fat diet.

The chart below compares the differences in the change in blood sugar clearance during each of the two diets. The blood sugar response is shown for both low and high doses of insulin.

Low and High Fat Diets on Blood Sugar Clearance

These results cannot be explained by changes in body weight or abdominal fat, since the participants’ weight remained the same during the study.

The researchers speculated that the saturated fat in the high-fat diet may have contributed to the decrease in insulin sensitivity, which is supported by other studies.

In one study, when healthy participants followed a diet high in saturated fat (17% of calories) for three months, insulin sensitivity decreased by 12.5% (9).

Other studies have shown that single meals or diets high in polyunsaturated or monounsaturated fat improve insulin sensitivity, compared to saturated fat (910111213).

These studies indicate that insulin sensitivity is influenced by the type of fat eaten, rather than the total dietary fat content. However, further studies are needed.

Bottom Line: The high-fat diet reduced insulin sensitivity, whereas it remained constant on the low-fat diet.

Finding 2: Increases in Skin Fat Were Associated With Higher Insulin Sensitivity

Why the high-fat diet reduced insulin sensitivity is unclear. However, the researchers observed a few significant associations.

During the low-fat diet, the researchers found that increases in the amounts of skin fat were associated with better insulin sensitivity.

Although there was a similar trend during the high-fat diet, the association was not statistically significant.

Conversely, on both diets, an increase in the content of omega-6 docosapentaenoicacid in very-low-density lipoproteins (VLDL) was associated with reduced insulin sensitivity.

Yet it should be noted that these were observational findings, and do not prove a causal relationship.

Bottom Line: Increased skin fat was associated with increased insulin sensitivity. Conversely, high blood levels of omega-6 docosapentaenoic acid were associated with reduced insulin sensitivity.

Limitations

This study was nicely designed, but had a few minor limitations.

First, the study was very small, including only 13 participants. For this reason, it may not have had the statistical power to detect smaller differences as significant.

Second, the dropout rate was very high, or 46%, indicating that dietary adherence may have been difficult.

Third, the study was designed to compare the effects of high-fat and low-fat diets on insulin sensitivity. Therefore, it does not provide any evidence for the effects of saturated fat on insulin sensitivity.

Finally, the study included individuals with normal blood sugar control, and the high-fat diet contained higher amounts of fat than are typically consumed. As a result, the findings may not apply to diabetics or those who consume lower amounts of fat.

Bottom Line: This study was very small and the dropout rate was high. Additionally, the findings may not apply to normal real-life settings or people with type 2 diabetes.

Summary and Real-Life Application

In short, this study suggests that a diet very high in fat, or saturated fat, make the body less sensitive to the effects of insulin.

However, the results may only apply to very high amounts of fat or specific types of fatty acids.

Gluten Sensitivity – Is it All in Your Mind?

Gluten is a protein found in certain grains, especially wheat.

There are some people who react negatively when they eat gluten and experience adverse symptoms.

There is one well-defined disease called celiac disease, and then another more controversial condition called gluten sensitivity.

Celiac disease affects about 0.7-1% of people (1), but the numbers for gluten sensitivity range from 0.5-13% depending on the study (2).

Some experts even believe that gluten sensitivity isn’t a real condition.

Study Reviewed

Today’s study may be able to shed some light on gluten sensitivity and the usefulness of removing gluten from the diet.

Capannolo A, et al. Non-Celiac Gluten Sensitivity among Patients Perceiving Gluten-Related Symptoms. Digestion, 2015.

This study looked at almost 400 people who believed that they were gluten intolerant, and investigated whether these people actually benefitted from a gluten-free diet.

Introduction

Gluten intolerance is a general term used for adverse reactions to gluten in wheat, rye and barley.

It can be divided into two distinct conditions; celiac disease and gluten sensitivity.

Celiac disease is an autoimmune disorder in genetically predisposed people. It is triggered by the consumption of gluten. It is a serious condition, and most people who have it don’t know about it.

However, gluten sensitivity (often termed non-celiac gluten sensitivity, or NCGS) is a more controversial condition. It is not as easily identified, and its existence is debated.

Gluten sensitivity is claimed to be characterized by various adverse symptoms. These include digestive discomfort, bloating, diarrhea, constipation, fatigue, headache, anxiety, depression, skin rashes, sore joints and weight loss.

The diagnosis is based on the following criteria:

  • Gluten intolerance is suspected.
  • A gluten-free diet alleviates symptoms, and symptoms reappear on exposure to gluten.
  • Celiac disease and allergies have been ruled out.

Many scientists have speculated that gluten sensitivity is a misnomer – that it is caused by substances other than gluten.

Some researchers even believe that it’s all in the minds of people. No matter what kind of sickness people suffer from, it’s all blamed on wheat and gluten.

Aim of the Study

The aim of the current study was to find out how many of those with self-reported gluten intolerance actually had celiac disease, non-celiac gluten sensitivity or wheat allergy.

Methods and Results

A total of 392 participants, both men and women, were included in the study.

They had one thing in common – they all complained of various general symptoms and believed them to be caused by gluten.

First, the researchers thoroughly tested all of the participants for celiac disease and wheat allergy.

Only 26 participants (6.6%) were positively diagnosed with celiac disease, and two (0.5%) turned out to be allergic to wheat.

This left 364 people who believed they reacted adversely to gluten, without a positive diagnosis of celiac disease or wheat allergy.

To investigate if any of the remaining participants had gluten sensitivity, they were put on a gluten-free diet for 6 months.

Then, those who experienced benefits while on the gluten-free diet were submitted to a “gluten re-challenge”. The gluten re-challenge involved going on a gluten-containing diet for a month.

To increase compliance, all participants were interviewed by a nutritionist on a monthly basis.

The diagnosis criteria of gluten sensitivity were the following:

  1. The participant had to experience benefits on the 6-month gluten-free diet.
  2. Going back on a gluten-containing diet caused the symptoms to return.

According to the study results, only 27 (7%) of the participants fulfilled these criteria, and were identified as “gluten sensitive”.

For this reason, the researchers concluded that only 14.5% of those who complained of gluten intolerance actually had issues with gluten or wheat.

On the other hand, 86% of people were wrong in their suspicions. Their symptoms were not relieved on a gluten-free diet, and their symptoms did not worsen when they started eating gluten again.

Here is an overview of the results:

Conclusions

The main conclusions of this study are:

  1. The majority of people who complain of gluten intolerance do not suffer from gluten intolerance. Their symptoms have other causes.
  2. Gluten sensitivity is about as common as celiac disease in people who claim that they are gluten intolerant.

Limitations

The study had several limitations.

First, there was no control group in the study. All participants were submitted to the same treatment.

It is impossible to know whether it was actually the gluten-free diet that caused improvements in symptoms among those 27 people who reported a positive change.

The improvement could simply have been due to chance. Symptoms tend to change naturally over time and are influenced by various lifestyle factors.

Second, the participants knew they were on a gluten-free diet. They also knew when they were submitted to a gluten re-challenge.

It can’t be ruled out that changes in symptoms were due to a placebo effect.

Third, self-reported symptoms are difficult to quantify, and there may be high variability in how people perceive and report symptoms.

In short, the study had several major design flaws, so the results should be taken with a grain of salt.

What Do Other Studies Say?

Randomized controlled trials are the gold standard in nutrition research.

So far, three randomized controlled trials have investigated gluten or wheat sensitivity.

Two of these studies have shown that people with irritable bowel syndrome (IBS – a common digestive disorder) but not celiac disease experience improvements on a gluten-free diet (34).

These studies support gluten sensitivity as a real condition, and indicate that a gluten-free diet can be beneficial in people who don’t have celiac disease.

However, other researchers believe that these benefits are not caused by removing gluten, but other problematic substances in wheat, mostly FODMAPs.

FODMAPs are short-chain carbohydrates that are poorly absorbed and cause digestive problems in many people.

One study fed isolated gluten to people who were not eating any FODMAPs. This study found no consistent adverse effects from gluten (5).

The study indicated that the benefits of gluten-free diets may be because these diets also remove wheat, which is a major source of FODMAPs.

As a result, some people claim that “wheat sensitivity” may be a more accurate term than “gluten sensitivity”. In those that do not have celiac disease, the benefits of removing wheat probably do not have anything to do with gluten.

Summary

The main message of this study review is that the great majority of people who think they are intolerant to gluten don’t actually benefit from a gluten-free diet.

The study indicates that non-celiac gluten sensitivity is about as common as celiac disease. The prevalence of celiac disease is around 0.7-1%.

However, the study has some major limitations so it cannot really provide any firm conclusions.

Given the body of evidence, non-celiac gluten sensitivity still probably exists, but it may be relatively rare.

The debate of gluten sensitivity is still up in the air, and we will review new studies as they come.

Real Life Applications

All this being said, if you consistently feel bad after eating gluten-containing cereals, you should definitely go on a gluten-free diet and see if your symptoms improve.

Even if you don’t have celiac disease, a gluten-free diet may be worth trying. In fact, there is no nutrient in wheat, barley and rye that can’t be provided by other foods.

Gluten- and wheat-free diets may have benefits for some people, but there is currently no evidence that warrants prescribing them to the general population.

In fact, the current study suggests that the majority of people would not benefit from such a diet, even people who believe that gluten causes them problems.

New Study Shows That Reducing Saturated Fat is (Almost) Useless

For decades, saturated fat has been believed to be harmful.

This is claimed to be because saturated fat raises blood levels of cholesterol inside LDL lipoproteins, which is a risk factor for cardiovascular disease (heart disease and strokes).

This is often referred to as the diet-heart hypothesis.

However, several major studies in recent years have challenged the diet-heart hypothesis and failed to find a relationship between saturated fat consumption and cardiovascular disease (12).

Study Reviewed

A new study recently came out that looks at the relationship between saturated fatconsumption and the risk of cardiovascular disease.

Hooper Lee, et al. Reduction in saturated fat intake for cardiovascular disease.The Cochrane Database of Systematic Reviews, 2015.

This is a systematic review and meta-analysis performed by the Cochrane collaboration, an independent organization of scientists that do objective and highly thorough reviews of randomized controlled trials.

When it comes to the quality of scientific evidence, it really doesn’t get much better than a Cochrane review.

Materials and Methods

The researchers searched the literature for randomized controlled trials that fulfilled certain criteria.

These included, but were not limited to:

  • There was a control group in each study.
  • The study instructed participants to reduce saturated fat, or replace it with other types of fats.
  • The study lasted for at least 24 months.
  • The study looked at hard end points, such as heart attacks and death.

All in all, 15 randomized controlled trials with over 59,000 participants were included.

Results

There were several interesting findings in the study.

Cardiovascular events

A cardiovascular event can refer to several different things. The study defined a “cardiovascular event” as:

“Combined CVD events. These included data available on any of the following: cardiovascular deaths, cardiovascular morbidity (non-fatal myocardial infarction, angina, stroke, heart failure, peripheral vascular events, atrial fibrillation) and unplanned cardiovascular interventions (coronary artery bypass surgery or angioplasty).”

In the current review, intervention that reduced saturated fat intake led to a 17% reduction in cardiovascular events. The quality of evidence was deemed “moderate.”

All-cause mortality

All-cause mortality refers to death from any cause, including heart attacks, cancer, accidents and others.

This study showed that reducing saturated fat has no statistically significant effect on total mortality. In other words, you are just as likely to die if you significantly cut back on saturated fat intake.

Cardiovascular mortality

Cardiovascular mortality implies death caused by either heart attacks or strokes. These are currently the two of the world’s most common causes of premature death.

This study did not find any benefit of reducing saturated fat. In other words, those who reduced their intake of saturated fat were just as likely to die from heart attacks or strokes.

Fatal heart attacks

The study almost found a small reduction in fatal heart attack risk by reducing saturated fat. The risk ratio was 0.95, or a 5% reduction in risk.

However, this was not statistically significant.

Non-fatal heart attacks

The study found no reduction in non-fatal heart attacks.

Strokes

There were no reductions in strokes (bleeding or a blood clot in the brain) in groups who restricted their saturated fat intake.

Summary

All in all, the only benefit of reducing saturated fat intake was found in cardiovascular events. There was no statistically significant effect on mortality, death from cardiovascular disease, heart attacks or strokes.

However, when they analyzed the studies further, they found a significant reduction in cardiovascular events only when saturated fat was being replaced with polyunsaturated fats.

In other words, reducing saturated fat had no effect on its own, but replacing it with polyunsaturated fats led to a 27% reduced risk of cardiovascular events (but not death, heart attacks or strokes).

They also found that the people who had the greatest reduction in serum total cholesterol were the most likely to experience a benefit.

This implies that changes in fat intake may be beneficial when they actually lead to a significant improvement in blood lipids.

Conclusions

These were the conclusions of the study:

“The findings of this updated review are suggestive of a small but potentially important reduction in cardiovascular risk on reduction of saturated fat intake. Replacing the energy from saturated fat with polyunsaturated fat appears to be a useful strategy, and replacement with carbohydrate appears less useful, but effects of replacement with monounsaturated fat were unclear due to inclusion of only one small trial.

This effect did not appear to alter by study duration, sex or baseline level of cardiovascular risk. Lifestyle advice to all those at risk of cardiovascular disease and to lower risk population groups should continue to include permanent reduction of dietary saturated fat and partial replacement by unsaturated fats. The ideal type of unsaturated fat is unclear.”

Cochrane reviews tend to be very conservative in their conclusions. Even though the data clearly suggests that reducing saturated fat is next to useless, they still claim in their conclusion that this is useful advice.

In this case, the study’s conclusions are not supported by the data.

Limitations

It is hard to find any limitations to this study. It is just about as good as it gets when it comes to studies on nutrition.

The only major flaw is the misleading conclusion.

What Other Studies Say

The findings of this study are similar to a previous Cochrane review that was done in 2011 (3).

It is also in line with findings from other recent systematic reviews and meta-analyses that did not find a link between saturated fat intake and heart disease (12).

Summary

Despite the strange conclusion of the study authors, the data they derived from their review is another nail in the coffin of the diet-heart hypothesis.

This high-quality study shows that reducing saturated fat has no effect on heart attacks, strokes or the risk of dying from all causes.

However, there may be a modest cardiovascular benefit to replacing saturated fats with polyunsaturated fats, such as those found in fish, nuts and olive oil.

According to this current study, this is unlikely to prolong your life, but it may reduce your risk of experiencing a cardiovascular event slightly.

Importantly, despite saturated fat not being harmful in reasonable amounts, this does not mean that people should go out of their way to eat more of them.

This study only looked at people using reasonable amounts of saturated fat, and does not exonerate bulletproof coffee users – which are using much higher amounts of saturated fat than the participants in this review.

Real Life Applications

Saturated fats appear to be neither good, nor bad. They are just neutral.

However, we do know that there are fats out there that have actual benefits.

Emphasizing foods that contain healthy fats, such as fish, nuts, seeds and extra virgin olive oil, may lead to a net health benefit.

In other words, don’t avoid saturated fats, but still try to prioritize whole foods that contain fats that have clearly been shown to be healthy.

Review: Health Benefits of Sustained Weight Loss

There is much more to weight loss than meets the eye.

In fact, weight loss is associated with multiple health benefits, and may be the single most important thing you can do to improve your health (if you are overweight).

Article Reviewed

A recent review article in the magazine Annual Review of Nutrition provided a comprehensive overview of the health benefits of maintaining weight loss in the long term.

Rueda-Clausen et al. Health Benefits of Long-Term Weight Loss Maintenance. Annual Reviews of Nutrition, 2015.

Aims

The main aim of the review was to summarize the evidence for the risks and benefits of sustained weight loss.

How is Sustained Weight Loss Defined?

Before discussing weight loss maintenance, it is important to explain or define what that means exactly.

Several researchers have come up with their own definitions.

Wing and Hill defined sustained weight loss in the following way (1):

Sustained weight loss is an intentional weight loss that has been maintained for at least a year. Additionally, it is equivalent to at least 10% of the initial body weight before deciding to lose weight.

The 10% cut-off value was based on the fact that previous studies had shown metabolic benefits from weight loss of that magnitude (23).

Further weight loss may have additional benefits.

It is Difficult to Determine the Health Benefits of Weight Loss

It can be very hard to determine the independent effects of weight loss on health.

There are a few reasons for this:

  • Dietary changes: Weight loss is usually accompanied with changes in diet. Dietary changes may have very strong effects on health.
  • Increased exercise: Weight loss is often associated with increased exercise. On its own, exercise may have immense health benefits.
  • Calorie restriction: Negative energy balance, the main reason for weight loss, also has huge health benefits.

As a result, it very difficult (or impossible) to isolate the health benefits of the weight loss itself.

This is also the reason why weight loss strategies may have powerful effects on health outcomes, even though the weight loss itself is minimal.

Health Benefits of Weight Loss Maintenance

According to this review, losing weight and keeping it off may improve:

  • Blood pressure: Losing weight may significantly improve blood pressure.
  • Heart health: Weight loss has been associated with improved heart health and a reduction in risk factors.
  • Type 2 diabetes: In people with insulin resistance (impaired glucose tolerance), weight loss may reduce the risk of type 2 diabetes or slow its progression.
  • Blood sugar control: In people with type 2 diabetes, weight loss leads to better blood sugar control.
  • Blood lipid profile: Weight loss causes improvements in the levels of blood lipids, reducing triglycerides and increasing HDL cholesterol.
  • Osteoarthritis: Weight loss may reduce symptoms in people with osteoarthritis.
  • Obstructive sleep apnea: Although weight loss rarely resolves obstructive sleep apnea completely, it may significantly improve symptoms.
  • Obesity hyperventilation syndrome: Substantial weight loss can improve symptoms in people with obesity hyperventilation syndrome.
  • Asthma: Weight loss maintenance may significantly improve asthma symptoms.
  • Cancer: There is some evidence to indicate reduced risk of cancer with sustained weight loss.
  • Quality of life: Health-related quality of life is significantly improved with weight loss.
  • All-cause mortality: Studies suggest that weight loss may be linked to reduced risk of all-cause mortality.

Does Short-Term Weight Loss Have any Benefits?

Short-term weight loss has many benefits, similar to sustained weight loss.

The difference is that the health benefits of short-term weight loss are limited to the actual weight loss period. When people start regaining weight, health status may start worsening accordingly.

However, some studies indicate that short-term weight loss may have health benefits in the long term. This phenomenon is called the “legacy effect” or the “metabolic memory effect” (4).

Health Risks of Weight Loss

When it comes to health and nutrition, very few things are perfect.

There are usually some downsides, but many of them may depend on the individual or be limited to specific situations.

In addition, the weight loss method affects the potential health benefits and risks considerably.

Weight loss methods can be divided into three main categories:

  1. Behavioral: This group of weight loss methods includes diets and exercise programs.
  2. Pharmacological: This category includes weight loss methods that involve medications and supplements.
  3. Surgical: When other methods fail, liposuction and other surgical methods, such as gastric bypass, are occasionally used to treat obesity.

In general, behavioral weight loss methods are considered the safest approach, whereas pharmacological and surgical procedures are more risky.

Apart from potential complications associated with surgical methods and medications, weight loss may worsen symptoms in the following diseases:

  • Non-alcoholic fatty liver disease: In people with non-alcoholic fatty liver disease, fast weight loss may worsen liver health.
  • Gallbladder disease: Weight loss may increase the risk and severity of gallbladder disease.

Take Home Message

It is clear that intentional, sustained weight loss may have significant beneficial effects on various health outcomes.

However, it is difficult to isolate weight loss from other lifestyle factors that are unavoidably associated with weight loss. These include increased exercise, changes in diet and calorie restriction.

In certain individuals, weight loss may worsen liver health and gallbladder disease. However, other health benefits far outweigh possible adverse health effects.

In short, if you are obese and want to improve your health, losing weight may be the single most effective way to do that.

7 Days of Overeating and Inactivity Causes Insulin Resistance

Obesity is one of the most common consequences of the Western lifestyle.

Unsurprisingly, obesity is not only a matter of weight. It is also associated with a variety of health problems.

The most common health problems associated with obesity are collectively known as metabolic syndrome.

Insulin resistance and type 2 diabetes are among the main components of this syndrome, but how they are linked with obesity is not clearly understood.

Article Reviewed

A team of scientists at Temple University, Philadelphia, set out to investigate how overeating and obesity may be linked with insulin resistance.

Boden et al. Excessive Caloric Intake Acutely Causes Oxidative Stress, GLUT4 carbonylation, and insulin resistance in healthy men. Science Translational Medicine 2015.

Materials and Methods

Six healthy, middle-aged men volunteered to participate in the study.

Half of them were normal weight, while the rest were slightly overweight.

None of them had a family history of diabetes or other endocrine disorders, and they were not taking any drugs.

They spent one week at a hospital, where they were overfed and confined to their rooms to minimize physical activity.

Their diet consisted of approximately 6000 kcal per day, a whopping 200–250% increase in their normal calorie intake.

It was a typical US diet, standardized to 50% carbohydrate, 35% fat and 15% protein.

Various blood analyses were done every day, while other measurements, such as fat biopsies, were only performed at the beginning and end of the study. Body weight and composition were also measured.

Results

By the end of the study, the participants had gained an average 3.5 kg, all in the form of fat mass.

On day two, insulin levels rose quickly with signs of increased insulin resistance, gradually becoming worse as the study progressed.

This chart shows how fasting insulin changed during the study (increased by 150%):

In addition, oxidative stress increased significantly during the study.

The source of this oxidative stress was found in fat tissue, as evident from fat biopsies. Apparently, fat tissue is particularly stressed during periods of overeating.

Most importantly, the study strongly suggests that oxidative stress was the cause of insulin resistance in the study participants.

In fact, oxidative stress appears to inactivate GLUT-4, an insulin-regulated glucose transporter mainly found in fat tissue and muscles.

Insulin resistance did not seem to be triggered by elevated levels of free fatty acids (FAA) or increased inflammation. Both remained constant during the study period.

Main Conclusions

This study showed that overfeeding causes insulin resistance.

It indicates that insulin resistance is caused by oxidative stress associated with increased storage of fat in fat tissue.

The oxidative stress seems to disrupt blood sugar regulation by damaging GLUT4, a protein responsible for transporting glucose from the bloodstream into cells.

Limitations

Apart from the small number of participants, the study doesn‘t have any obvious limitations.

However, for comparison, it would have been useful to have a control group receiving a weight-maintenance diet.

As the researchers point out, inactivity is likely responsible for a part of the adverse changes seen in the study.

What Do Other Studies Say?

A slower and less pronounced increase in insulin resistance has been found in other studies feeding participants less amounts of excess calories.

One 8-week study in 29 healthy men investigated the effect of increasing calorie intake by 40%. It found an 18% increase in insulin resistance (1).

Another study in 40 healthy men and women showed that eating an excess of 1040 kcal/day for a month decreased insulin sensitivity by 8% (2).

Previous research also indicates that insulin resistance is linked with oxidative stress and that adipose tissue is heavily stressed during overeating (34567).

For this reason, several human trials have tried to decrease insulin resistance by using antioxidants (compounds that act against oxidative stress). However, their results have been inconsistent (89101112).

The results of the current study are supported by studies of cells in test tubes, showing that oxidative stress causes insulin resistance on the cellular level (131415).

Studies in humans and animals also indicate that a high-fat diet increases oxidative stress and insulin resistance (7).

Summary

In short, this study clearly shows that drastic overeating and inactivity are seriously unhealthy. They increase oxidative stress and cause insulin resistance in as little as two days.

Oxidative stress impairs blood sugar regulation by inactivating a protein called GLUT4, responsible for transporting glucose from the bloodstream into cells.

Simply put, overeating and lack of exercise may explain what causes insulin resistance – a leading driver of metabolic syndrome and type 2 diabetes, which are currently massive health problems worldwide.

Does Eating or Skipping Breakfast Affect Weight Loss?

The importance of eating breakfast is frequently highlighted in public health recommendations.

However, the supporting evidence is limited and mainly based on observational studies and short-term clinical trials (12).

Study Reviewed

A recent study investigated whether dietary recommendations were more effective at promoting weight loss when coupled with the advice to either eat or skip breakfast.

Dhurandhar et al. The effectiveness of breakfast recommendations on weight loss: a randomized controlled trial. American Journal of Clinical Nutrition, 2014.

Materials and Methods

This 16-week randomized controlled trial took place in multiple locations in Europe and the USA.

A total of 309 overweight or obese men and women between the ages of 20 and 65 were recruited in the study.

At the start of the study, all participants got dietary recommendations from the USDA in the form of a pamphlet.

Participants were then randomly assigned to one of three groups:

  1. Breakfast: Advice to eat breakfast before 10 AM every day.
  2. No breakfast: Advice to eat nothing before 11 AM every day.
  3. Control: No advice regarding breakfast.

The randomization procedure was stratified, meaning that the initial breakfast skippers and eaters were randomized separately. This was done to minimize bias.

To increase compliance, the participants got phone call reminders on weeks 4, 8 and 12.

Compliance was also checked with daily diaries in which the participants indicated whether they were able to follow the breakfast recommendations or not.

Body weight and height were measured at the start of the study. Weight was measured again at the end.

The main outcome measure was weight change during the course of the study. The weight change was then compared between groups.

Results

The study did find that the recommendations were effective at changing people’s breakfast habits.

In other words, those who were asked to skip breakfast managed to do so, and those who were asked to eat breakfast did so as well.

However, there was no significant difference in weight loss between groups.

This chart shows the weight loss among the study groups, divided into two parts depending on the participants’ eating habits before the study.

As you can see, the difference between groups is small and insignificant. All groups lost a bit of weight, but the difference between groups was less than half a pound.

A total of 283 participants finished the study, but 26 dropped out for various reasons.

Main Conclusion

The main conclusion is that recommendations to skip or eat breakfast do not have any significant effects on weight loss in overweight/obese men and women.

Limitations

The study does not have any major limitations.

However, it would have been useful if the study had measured body composition or other metabolic variables instead of just body weight.

In addition, the study was only 16 weeks. It is possible that the study was too short to detect long-term effects.

As pointed out by the researchers, the study indicates that breakfast recommendations do not influence weight loss in a free-living setting.

However, it does not rule out the possibility that breakfast habits can affect weight loss in a controlled setting.

Strengths

So far, this is the largest randomized controlled trial on the effect of breakfast recommendations on weight loss.

The large number of participants and multiple study sites ensure adequate statistical power and allow the results to be generalized.

What Do Other Studies Say?

Observational studies indicate that eating breakfast is linked with lower body weight (34567).

However, observational studies can only provide suggestive evidence. There may be other beneficial factors in people’s lifestyles that are also associated with the habit of eating breakfast.

Several short-term clinical studies have investigated the issue. They indicate that breakfast may promote weight loss (891011).

Unlike the current study, these studies aimed at explaining potential mechanisms in a controlled setting. They were also of much shorter duration.

One 12-week study investigated the effect of skipping breakfast in 52 moderately obese women (12).

Supporting the results of the current study, there were no significant differences between groups. However, there was a non-significant trend towards greater weight loss in those who had breakfast.

Recently, several scientists have pointed out that the evidence regarding the effect of breakfast habits on obesity is severely limited (12).

Summary

In short, this study suggests that advising people to either skip or eat breakfast has no effects on weight loss.

Although it doesn’t rule out that breakfast habits may have metabolic consequences, it strongly suggests that breakfast recommendations do not have a significant impact when people are trying to lose weight.

Mediterranean Diet With Olive Oil Slashes Breast Cancer Risk by 62%

Breast cancer is the most common cancer in women. About 12.3% of women will experience breast cancer at some point in their life (1).

Even though modern medical treatments work well in many cases, it still causes about half a million deaths per year.

Breast cancer has become increasingly more common in the past few decades, which may be attributed to our modern lifestyles (2).

Several observational studies have suggested that a “Mediterranean” diet pattern may reduce the risk of breast cancer (34), although other observational studies have found no effects (56).

Study Reviewed

Today’s study is the first randomized controlled trial that looks at the effect of the Mediterranean diet on breast cancer risk.

It is an analysis based on data from the massive PREDIMED study, the largest study ever done on the Mediterranean diet.

Estefania Toledo, et al. Mediterranean Diet and Invasive Breast Cancer Risk Among Women at High Cardiovascular Risk in the PREDIMED Trial. JAMA Internal Medicine, 2015.

Aim of The Study

The aim of the study was to evaluate the effects of a Mediterranean diet, supplemented with either extra virgin olive oil or nuts, on the risk of breast cancer.

How The Study Was Designed

This paper is based on the famous PREDIMED study, a large multicenter randomized controlled trial on the Mediterranean diet.

The study was originally designed to test whether a Mediterranean diet reduced the risk of cardiovascular disease, which it did (7).

This part of the study only evaluated women, not men. The women were between 60 to 80 years of age, had no heart disease, but had either type 2 diabetes or at least 3 major risk factors for heart disease.

The trial included a total of 4282 women, which were randomized into 3 different diet groups:

  1. A Mediterranean diet supplemented with extra virgin olive oil (MED+EVOO).
  2. A Mediterranean diet supplemented with nuts (MED+Nuts).
  3. A “low-fat” diet (control group).

Those in the olive oil group received a liter (34 oz) of extra virgin olive oil per week, while those in the nut group received 30 grams (1 oz) per day of mixed nuts. These foods were provided to the participants for free.

Both group and individual sessions with dietitians were included to ensure compliance to the prescribed diets. Compliance was evaluated using dietary screening questionnaires.

There were no recommendations to cut calories or increase physical activity in any group.

The women in the study were followed for an average of 4.8 years.

Results

After a 4.8 year study period, 35 cases of malignant breast cancer were confirmed.

Relative to the “low-fat” control group, the risk of breast cancer was lower in both of the Mediterranean diet groups:

  • Med+Nuts: 38% lower risk, not statistically significant.
  • Med+EVOO: 62% lower risk, statistically significant.

This graph shows the differences between the groups (click for a larger version):

When all participants were analyzed, the 20% who consumed the most extra virgin olive oil had a whopping 82% lower risk of breast cancer compared to the 20% who consumed the least.

Additionally, each 5% increase in percentage of calories from extra virgin olive oil was linked to a 28% lower risk of breast cancer. Women who consumed over 15-20% of calories from extra virgin olive oil had the lowest risk.

Main Conclusions

According to this study, a Mediterranean diet can lead to a reduced risk of breast cancer if supplemented with extra virgin olive oil.

Additionally, a dose-response relationship was found. As in, the more extra virgin olive oil the women consumed, the lower their risk of breast cancer was.

The study did not find a statistically significant effect in the Mediterranean diet group that supplemented with nuts.

Biological Mechanism

The exact mechanism behind the breast cancer-lowering effects is not fully known at this point.

However, there are several possible explanations:

  • The mechanism may have something to do with reduced oxidative stress on a Mediterranean diet (89).
  • Extra virgin olive oil also contains many beneficial plant compounds, including powerful polyphenol antioxidants (1011).
  • Oleic acid, the main fatty acid in olive oil, has also been shown to have anti-cancer effects in some studies (12).
  • Other compounds in extra virgin olive oil that may have anti-cancer effects include squalene and lignans (1314).

Limitations

The study did have some notable limitations:

  1. The study was designed with the end point of cardiovascular disease in mind, not breast cancer.
  2. Some data on breast cancer, either before or during the study, may be missing because it wasn’t tracked as well as heart disease.
  3. The cases of breast cancer in the study were relatively few, only 35.
  4. This study included white postmenopausal women at high cardiovascular risk. The results may not apply to other age groups or ethnicities.
  5. The Mediterranean diet groups got better social support than the control group in the beginning of the study.
  6. The women in the “low-fat” control group did not reduce their fat intake substantially, so they were not really eating a low-fat diet.

Overall, however, the study was very well designed. It was a long-term randomized controlled trial looking at hard end points instead of just risk factors. This is about as good as it gets in studies on nutrition.

What do Other Studies Say?

As mentioned above, results from observational studies have been inconsistent.

Some of them show that people who follow a Mediterranean diet “pattern” have a lower risk of cancer (34), while other studies find no effects (56).

One other large randomized controlled trial has been done on the Mediterranean diet and cancer risk.

This study was called the Lyon Diet Heart study, and it showed that a Mediterranean diet reduced the risk of overall cancer (not just breast cancer) by 61% (15).

Summary and Real Life Applications

According to this study, a Mediterranean diet reduces breast cancer risk in women, especially when supplemented with extra virgin olive oil.

This study also shows that the women who eat the most extra virgin olive oil have the lowest risk of breast cancer, by far.

Combined with the cardiovascular benefits (7) and overall cancer risk reduction (15) of the Mediterranean diet, these are compelling reasons to follow a Mediterranean diet if your goal is to live a long life and reduce your risk of chronic disease.

This study also provides a compelling reason to eat more extra virgin olive oil. It also has numerous other benefits, which you can read about in this article here from 2014.

Extra virgin olive oil really may be the healthiest fat you can eat. It seems like a good idea to eat it in place of other cooking fats. It is a myth that olive oil is a poor choice for cooking.

Do All Fruits and Vegetables Help You Lose Weight?

Eating a variety of fruits and vegetables has been associated with improved health and a reduced risk of chronic disease.

The current Dietary Guidelines for Americans even recommend them for weight loss.

However, not all fruits and vegetables are equal when it comes to weight loss or maintenance. They may have different metabolic effects, depending on their nutrient composition.

Body weight may be affected by glycemic load and amount of fiber, as well as polyphenols and sugar content (1234).

Study Reviewed

A team of researchers hypothesized that fruits and vegetables with a high fiber content or a low glycemic load would be more strongly associated with weight loss.

To prove or disprove this hypothesis, they did a meta-analysis of three observational studies that spanned up to 24 years.

Bertoia et al. Changes in Intake of Fruits and Vegetables and Weight Change in United States Men and Women Followed for Up to 24 Years: Analysis from Three Prospective Cohort Studies. PLOS Medicine 2015.

Aims

The purpose of the study was to investigate the association of increased fruit and vegetable intake and changes in weight over time.

Additionally, the researchers wanted to find out if fiber-rich, low-glycemic fruits and vegetables were more strongly associated with weight loss and weight maintenance than their fiber-poor and high-glycemic counterparts.

Study Design

The study combined data from three large observational studies, using a method known as random effects meta-analysis.

These three observational studies were the Nurses’ Health Study, the Nurses’ Health Study II, and the Health Professionals Follow-up Study.

They included a total of 133,468 health professionals from the US, and spanned 24 years, from 1986 to 2010.

With 4-year intervals, dietary and lifestyle habits were estimated using questionnaires. Similarly, body weight was self-reported.

The study used a so-called “change-on-change” analysis. In other words, it examined the effect of changes in the consumption fruit and vegetables and compared them with changes in body weight.

A validated food frequency questionnaire was used to assess food intake. It included more than 70 fruits and vegetables (5).

The foods were classified as either high- or low-fiber, and as high- or low-glycemic, based on their glycemic load. Glycemic load was calculated by multiplying the serving size with the glycemic index of the food.

When analyzing the dietary data, other lifestyle factors and diseases were taken into account. These included other dietary aspects, physical activity, alcohol and smoking status.

Additionally, the calculations were only based on whole foods. Processed foods, such as fruit juice, french fries and potato chips, were excluded.

Results

This chart shows the weight loss for different classes of fruits and vegetables, based on one serving size:

The numbers show the pooled weight loss over four years, for each serving. As you can see, eating berries was most strongly associated with weight loss.

Several individual fruits and vegetables were also associated with weight loss. These included applespears, blueberries, raisins, grapes, prunes, grapefruit, soy, tofu, cauliflower, peppers and carrots.

In contrast, a few starchy vegetables appeared to promote weight gain.

As you can see, potatoescorn and peas were all associated with weight gain in the current study.

However, this only applied to servings that exceeded one serving per day.

Overall, these results indicate that eating fruits and (most) vegetables may help with weight loss and weight maintenance.

On the other hand, starchy vegetables, such as potatoes, peas and corn, may promote weight gain when eaten in excess.

All of these effects were stronger among overweight individuals than normal-weight individuals.

Fruits — Effect of Fiber and Glycemic Load

When fruits were examined, no association with weight change was found for fiber content or glycemic load.

Vegetables — Effect of Fiber and Glycemic Load

Low-fiber vegetables were associated with weight loss. Similarly, high-fiber vegetables were linked to weight loss, but only when potatoes were excluded.

Additionally, eating more than one serving of low-GL vegetables per day was linked to weight loss, but the significance was only marginal.

The results changed when high-fiber and low-GL vegetables were grouped together and compared with low-fiber, high-GL vegetables.

The difference was highly significant. High-fiber and low-GL vegetables were clearly better at promoting weight loss.

Main Conclusions

  • Increased vegetable and fruit consumption is linked to weight loss over time, especially among overweight individuals.
  • Fruits, especially berries, are more effective at promoting weight loss than vegetables.
  • Starchy, high-glycemic vegetables, such as potatoes, corn and peas, are associated with weight gain.

Limitations

This was an observational study (as opposed to a randomized controlled trial), and observational studies have many potential limitations.

They only provide hints, indicating a possible causal relationship, but cannot prove anything.

Even though the study showed strong associations, their cause remains unclear.

Additionally, the interpretation of observational studies is often difficult due to a type of bias known as confounding.

This means that factors, other than those that are being investigated, may be responsible for the observed relationship.

These factors are called confounders. In this study, the most important confounders — physical activity, smoking, and foods — were taken into account.

There are several other potential limitations.

  • The study used a validated food frequency questionnaire to estimate food intake (5). These questionnaires are prone to errors that may reduce the chance of finding significant associations.
  • It is possible that those individuals who were eating more fruit and vegetables for health reasons were also making other healthy lifestyle changes that were not completely captured by the study’s questionnaires.
  • Since the study mainly included white adults with graduate degrees, the results may not be generalizable to all people. However, the effects are unlikely to be different in other populations.

That being said, this study appears to be about as good as observational studies get.

What Do Other Studies Say?

Supporting the current study, other observational studies have found that increased fruit and vegetable intake is linked to weight loss (1678).

One observational study found a similar association that only applied to fruit, but not vegetables (9).

In contrast, another observational study did not detect any significant association of fruit and vegetable intake and weight change. However, it did not do a change-on-change analysis like the current study (10).

Clinical trials have also provided mixed results.

In 103 overweight individuals with sleep-related eating disorders, increased consumption of fruits and vegetables caused weight loss over 3 months (11).

Conversely, increasing vegetable and fruit intake did not have any significant effects on weight in 690 healthy individuals over a 6-month period (12).

Trials that have focused on eating specific fruits and vegetables support that some of them may benefit weight loss. Among these are apples, pears and grapefruit (1314).

Summary and Real-Life Application

Overall, the findings of the study support the dietary recommendations of eating fruits and vegetables for healthy weight.

However, not all vegetables are made equal.

The study indicates that excessive consumption of certain starchy vegetables may promote weight gain. These include potatoes, peas and corn.

In short, if you are overweight, consider eating more whole fruit and vegetables, but limit your intake of starchy vegetables.

Starvation Mode: When You Eat Less, Your Body Burns Less

Besides storing fat, the body has several methods to survive periods of food shortage and starvation.

One of them is called adaptive thermogenesis, sometimes referred to as “starvation mode.”

It involves a reduction in the amount of calories your body burns, resulting in slower weight loss and faster weight regain.

It is defined as a decrease in resting energy expenditure during calorie restriction, beyond what can be explained by reduced mass of muscles, organs and fat.

Adaptive thermogenesis is seen when people continuously restrict calories by dieting and/or exercising. It may also be caused by weight loss drugs or surgery (123).

Although adaptive thermogenesis is well-known, how it works remains unclear.

Empty Plate and Utensils

Article Reviewed

German researchers set out to investigate the causes and dynamics of adaptive thermogenesis (starvation mode).

They wanted to find out how body composition affects adaptive thermogenesis, whether it causes changes in hormones, and what effect it has on weight regain.

Muller et al. Metabolic Adaptation to Caloric Restriction and Subsequent Re-feeding: The Minnesota Starvation Experiment Revisited. American Journal of Clinical Nutrition 2015.

Study Design

The article describes the results of two related studies from Christian Albrechts University, in Germany.

The design was similar to the famous Minnesota Starvation Experiment from 1950, one of the most important early studies on the effects of starvation in humans (4).

Study 1

This 6-week intervention study included 32 healthy, non-obese men, between 20 and 37 years of age.

Before the intervention started, participants spent 10 weeks at the university’s metabolic ward where their energy needs were calculated.

The intervention was divided into three parts:

  1. Overfeeding: For one week, the participants were overfed so that their calorie intake exceeded their energy needs by 50%.
  2. Calorie restriction: For three weeks, the participants were semi-starved so that their calorie intake was 50% lower than their energy needs.
  3. Re-feeding: For two weeks, the participants were again overfed so that their calorie intake exceeded their needs by 50%.

All participants spent every day, from 8 AM to 6 PM, at the university’s metabolic ward, where they were measured and monitored.

Dietary intake was strictly controlled. All foods were weighed and all meals supervised.

Additionally, participants were encouraged to avoid any physical activity and to remain sedentary.

Compliance was ensured by using continuous 24-h glucose monitors, pedometers and dietary records.

Body composition was measured using various techniques. These included quantitative magnetic resonance and whole-body MRI.

The levels of various hormones and other relevant body processes were also analyzed throughout the study.

Study 2

A smaller follow-up study was done 1.5 years later than the original study.

This study included only eight of the participants that took part in the first study.

Its purpose was to estimate the effects of short-term calorie restriction on adaptive thermogenesis.

Additionally, it examined whether the results of the earlier study were reproducible.

It was divided into two parts:

  1. Overfeeding: Participants were overfed for one week.
  2. Calorie restriction: Participants were calorie restricted for one week.

Otherwise, the methods were similar to the first study.

Results

This chart below shows the changes in body composition over the course of the study (click to enlarge):

Calorie Restriction Results Smaller

The top graph shows change in body weight, the middle graph shows a change in fat mass, and the bottom graph shows nitrogen balance, which indicates changes in lean mass (mostly muscles and organs).

After three weeks of calorie restriction, body weight decreased by 6 kg (13.2 lbs – 7.5%) and resting energy expenditure dropped by 266 calories per day, on average.

Adaptive thermogenesis was detected in 60% of participants in the early stages of calorie restriction. It became significant on the third day.

It was partly responsible for the decrease in energy expenditure, accounting for 108 calories/day.

Of these 108 calories per day, 36 were explained by changes in the composition of fat-free mass, leaving 72 calories for “true” adaptive thermogenesis.

Factors that were associated with adaptive thermogenesis included reduced insulin levels, heart rate, kidney function and body fluid balance. Increased formation of glucose in the liver also appeared to play a role.

Adaptive thermogenesis was not associated with changes in sympathetic nervous system activity, total body fat, belly fat, liver fat, organ mass, nitrogen and sodium balances.

It was also not linked to hormonal changes, such as in leptin, ghrelin, adiponectin and thyroid hormone levels (T3).

Lastly, adaptive thermogenesis appears to have no long-term effects on weight or fat regain after short-term calorie restriction. The effect was reversed within two weeks of re-feeding.

Here you can see how energy expenditure changes from adaptive thermogenesis developed during the course of the study:

Adaptive Thermogenesis Chart

As you can see, the increase during the re-feeding phase completely reversed the decrease seen during the calorie restriction phase.

Several other parameters changed significantly during 3 weeks of severe calorie restriction:

  • Fat mass: Decreased by 114 grams per day.
  • Lean mass: Decreased by 159 grams per day (muscles and organs combined, see below).
  • Muscle mass: Decreased by 5%.
  • Liver mass: Decreased by 13%.
  • Kidney mass: Decreased by 8%.
  • Heart rate: Went down by 14%.
  • Blood pressure: Went down by 7%.
  • Creatinine clearance: Went down by 12%.
  • Energy cost of walking: Decreased by 22%.
  • Sympathetic nervous system activity: Decreased by 38%.
  • Leptin levels: Decreased by 44%.
  • Insulin levels: Decreased by 54%.
  • Adiponectin levels: Decreased by 49%.
  • Triiodothyronine (T3): Decreased by 39%.
  • Testosterone: Decreased by 11%.

Main Conclusions

The main conclusions of the study were as follows:

  • Adaptive thermogenesis is modest and kicks in during the early stages of starvation, shortly after calorie restriction starts. It is maintained as long as you keep restricting calories.
  • Adaptive thermogenesis appears to have no long-term effects on weight or fat regain after short-term calorie restriction.
  • Adaptive thermogenesis was partially explained by reductions in heart rate and kidney function, and increased formation of glucose in the liver.
  • In early calorie restriction, adaptive thermogenesis is also associated with a drop in insulin levels.

Limitations

The study has no apparent limitations. It was tightly controlled and had highly significant results.

However, since the participants were limited to healthy, sedentary, non-obese men, the results may not be generalized to all people.

For example, it is possible that the dynamics of of adaptive thermogenesis are vastly different in people with obesity.

What Do Other Studies Say?

In general, adaptive thermogenesis (AT) is considered to be an automatic response to food shortage.

In the Minnesota Starvation Experiment from 1950, resting energy expenditure declined by 39% (600 calories/day). About 35% of this decline was not caused by changes in body composition, which indicates that AT also played a role (4).

Additionally, studies in obese patients have detected adaptive thermogenesis amounting to 504 calories/day (56).

Reduced levels of leptin and thyroid hormone (T3) have often been considered as major determinants of AT (789).

Although the current study showed reductions in both leptin and T3, it did not support a causal relationship between AT and changes in these hormones.

This is supported by studies on obese patients after weight loss. They found no significant associations between AT and reductions in leptin and T3 (56).

Some studies indicate that AT may contribute to increased weight regain after calorie restriction (410).

This effect has been referred to as the “fat overshooting” phenomenon (7).

According to the current study, this effect is reversed within 2 weeks of re-feeding.

Summary and Real-Life Application

In short, adaptive thermogenesis (AT) is one of the main reasons your body starts burning fewer calories when you lose weight.

It is a part of the reason why weight loss tends to slow down over time, and is often referred to as “starvation mode.”

In the current study, significant adaptive thermogenesis was detected as early as on the third day of calorie restriction.

Unfortunately, there is no known way to completely prevent this from happening.

However, two effective ways to partly reduce muscle loss and metabolic slowdown during weight loss include strength training and keeping your protein intake high (101112).

Additionally, by exercising more and staying active throughout the day, you can negate some of the reduction in energy expenditure.

The Paleo Diet May Help Fight Metabolic Syndrome

In the past decade, the Paleolithic diet (or paleo diet) has gained considerable popularity due to its claimed health benefits.

However, it differs from official dietary recommendations in many ways. For example, it excludes all grains, dairy products and industrially processed food.

Several studies have investigated the health effects of the paleo diet. This meta-analysis examined its effects on metabolic syndrome.

Background

Metabolic syndrome is a group of adverse conditions associated with abdominal obesity.

These include the following risk factors for type 2 diabetes and heart disease:

  • Abdominal obesity.
  • Elevated blood sugar.
  • Elevated blood pressure.
  • High blood triglycerides.
  • Low HDL-cholesterol.

An underlying cause of metabolic syndrome is thought to be the modern processed diet, causing low-grade inflammation and insulin resistance (12).

For this reason, it is very likely that diets based on unprocessed, whole foods, like the paleo diet, may improve health among people with metabolic syndrome.

Study Reviewed

Scientists from Bahrain and the Netherlands did a meta-analysis of randomized controlled trials that compared the paleo diet with other dietary patterns.

Paleolithic nutrition for metabolic syndrome: systematic review and meta-analysis.

Basic Study Design

The researchers conducted a meta-analysis of randomized controlled trials.

They combined results from many conceptually similar studies and performed new statistical analyses.

This meta-analysis included four randomized controlled trials (IIIIIIIV) with a total of 159 participants.

The researchers then compared these findings to control diets based on nutrition guidelines from around the world.

The main research question of this review was: Does adhering to a Paleolithic diet improve metabolic risk factors?

Finding 1: The Paleo Diet Improved Body Composition

The paleo diet resulted in greater improvements in body composition than the diets based on official health recommendations.

Below is an overview of how the paleo diet differed from the control diets in the short-term. The numbers represent the mean difference.

  • Body weight: -2.69 kg (-5.9 lbs).
  • Waist circumference: -2.38 cm (-0.94 in).

Supporting this, a few other trials have shown that going on the paleo diet may reduce body weight and improve body composition (45).

Bottom Line: The Paleolithic diet resulted in greater reductions in body weight and waist circumference than diets based on official health recommendations.

Finding 2: The Paleolithic Diet Reduced Heart Disease Risk

Compared to the control diet, the Paleolithic diet also improved several other risk factors for heart disease.

  • Triglycerides: -0.40 mmol/L.
  • Systolic blood pressure: -3.64 mm Hg.
  • Diastolic blood pressure: -2.48 mm Hg.

HDL-cholesterol and C-reactive protein levels were also reduced, but the differences between the diets were not significant.

A few other human trials on the paleo diet have provided similar results (345).

Bottom Line: The Paleolithic diet resulted in greater improvements in heart disease risk factors than diets based on official nutritional recommendations.

Finding 3: Effects on Blood Sugar Control

The paleo diet resulted in significant reductions in both fasting blood sugar and insulin.

However, changes in blood sugar and insulin were not significantly different between diets.

One uncontrolled trial also showed significant improvements to blood sugar control on a paleo diet (3).

Bottom Line: The Paleolithic diet resulted in improvements in blood sugar control. However, the difference between diets was not significant.

How Does the Paleolithic Diet Improve Metabolic Syndrome?

There are several possible reasons why the paleo diet may have an advantage over conventional diets.

  • Paleolithic nutrition contains almost no carbs that are high on the glycemic index. Eating lots of high-glycemic foods may increase low-grade inflammation and the risk of insulin resistance (6).
  • Paleolithic diets contain no processed foods. They are exclusively based on whole foods, including fruits and vegetables.
  • Paleolithic diets contain no refined vegetable oils. Many vegetable oils are high in omega-6 fats, and may cause unfavorable ratios between omega-3 and omega-6. This may cause chronic, low-grade inflammation (78).

Bottom Line: Paleolithic diets do not contain any processed foods or foods that are high on the glycemic index. This may help prevent low-grade inflammation and reduce the risk of insulin resistance.

Limitations

This meta-analysis appears to be well designed and not have any serious limitations. The control diets were also relatively similar.

However, the included studies had a few potential limitations:

  • Most of the studies had few participants and were short in duration.
  • The paleo diet prescribed in the studies may not accurately represent what “paleo” eaters consume in the real world.
  • In three of the studies, the dietary intervention was in the form of advice and recommendations. Compliance may have been an issue in some of these studies (91011).
  • None of the included trials were fully blinded. This might have affected their results.
  • Although the present meta-analysis tried to standardize the time-point data, the duration still ranged from 2 weeks to 6 months (1011).
  • Although the test and control diets in all 4 studies were reasonably similar, there were some differences. Even slight variations in macronutrient composition may have strong effects on health outcomes.
  • One of the included trials had a baseline imbalance. Participants in the Paleolithic group had significantly worse outcome values at the start of the study compared to the control group (10).
  • Only one study reported adverse effects, and none of them assessed quality of life.

Summary and Real-Life Application

In short, the study shows that a paleo diet may have moderate benefits for metabolic syndrome.

However, the authors of the article believe that more evidence is needed before Paleolithic nutrition can be recommended in official guidelines.

Additionally, it is debatable whether total avoidance of dairy and grains is necessary, or even advantageous, for optimal health.

That being said, it is clear that avoiding processed foods and adhering to a diet based on whole foods is sound nutritional advice.

Probiotics May Help Prevent Weight Gain

Probiotics are bacteria that have health benefits when consumed. They are found in probiotic supplements and some fermented foods.

Several studies indicate that probiotics can be useful in the battle against weight gain and obesity (1).

This study examined the effects of a broad-spectrum probiotic supplement on weight gain during a high-fat, high-calorie diet.

Background

People who have obesity and/or type 2 diabetes may have more undesirable bacteria in their digestive system than beneficial bacteria (2).

Although the cause of this imbalance is not entirely clear, evidence indicates that high-fat, high-calorie diets may cause unfavorable changes in the bacterial environment in the gut (3).

This may be the cause of the systemic inflammation associated with obesity and metabolic syndrome (3456).

For this reason, dietary strategies that positively affect the gut bacteria may potentially benefit people with obesity or metabolic diseases.

One such strategy is supplementation with probiotic bacteria, like Lactobacillus and Bifidobacterium.

Previous studies have shown that probiotics may decrease the growth of undesirable bacteria and reduce inflammation in the digestive system (7).

Study Reviewed

Researchers at Virginia Tech set out to examine whether a probiotic supplement would reduce weight gain on a high-fat, high-calorie diet.

Probiotic Supplementation Attenuates Increases in Body Mass and Fat Mass During High-Fat Diet in Healthy Young Adults.

Basic Study Design

This was a 4-week, double-blind, randomized controlled trial in 20 healthy, non-obese men, aged 18–30 years.

The participants were randomly assigned to one of two groups:

  • Probiotic group: Participants received a broad-spectrum probiotic supplement called VSL#3. Two doses of VSL#3, each containing 450 billion probiotics of 8 different strains, were consumed daily in a milkshake.
  • Placebo group: Participants in the placebo group received milkshakes containing cornstarch instead of probiotics.

All participants were also put on a weight-gain diet, containing an excess of 1000 calories. This diet was high in fat, containing 55% fat, 30% carbs and 15% protein.

Several variables were measured at the beginning and the end of the study; these included body composition, insulin sensitivity, endotoxins and inflammatory markers.

Bottom Line: This was a 4-week, randomized controlled trial in 20 healthy, non-obese men. They were assigned to one of two groups: probiotic supplementation and placebo.

Finding 1: Probiotic Supplementation Reduces Weight Gain

The probiotic supplementation reduced gain in body mass and fat mass, compared to the placebo.

The chart below shows the difference in weight gain between groups.

These results are consistent with other studies that have reported weight loss in obese people taking probiotic supplements (89).

An additional study showed that taking probiotic supplements might reduce weight gain during 7 days of overfeeding (10).

The present study shows that these effects are sustained for up to 4 weeks.

How probiotics reduce weight gain is unclear, but it may have something to do with the amount of calories that are absorbed from the digestive system (1112).

Further studies are needed to determine exactly how this works.

Bottom Line: Probiotic supplements reduced gain in body mass and fat mass in people who were fed a high-fat, high-calorie diet.

Finding 2: Effects on Insulin Sensitivity

The high-fat, high-calorie diet did not affect insulin sensitivity in the participants.

Probiotic supplementation also had no effects on insulin sensitivity, and these results are consistent with a few previous studies (1314).

However, they conflict with one study showing that probiotic supplementation may prevent development of insulin resistance during 7 days on a high-fat, high-calorie diet (10).

Other studies also indicate that probiotic supplementation may reduce or prevent insulin resistance (15161718).

The reason for this inconsistency is unclear.

Bottom Line: Neither the high-fat diet nor the probiotic supplements had any effects on insulin sensitivity. Other studies have provided mixed results.

Finding 3: Effect on Endotoxins

Endotoxins, also known as lipopolysaccharides, are found in the membranes of some gut bacteria.

These compounds may find their way into the blood circulation of individuals with an imbalance in the bacterial environment in the gut.

In fact, previous studies have shown that high-fat, high-calorie diets may cause a small increase in the levels of endotoxins in blood (319).

In the present study, the levels of endotoxins did not change in either group.

Bottom Line: A high-fat, high-calorie diet did not affect levels of endotoxins in blood. Probiotic supplementation did not affect endotoxins either.

Finding 4: Effect on Inflammation

Systemic inflammation is estimated by measuring inflammatory markers in the blood.

The present study measured three inflammatory markers: C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α).

TNF-α increased significantly in both groups during the 4 weeks of the high-fat, high-calorie diet.

CRP did not change significantly during the study period. IL-6 seemed to increase, but the change was not statistically significant.

Probiotic supplementation had no effects on the change in inflammatory markers.

Bottom Line: The high-fat, high-calorie diet increased levels of TNF-α, a marker of inflammation. Probiotic supplementation did not affect this increase.

Limitations

The study was well designed. However, as in most studies, there were a few important limitations.

For starters, the number of participants was low. A larger number of participants would have increased the statistical power of the study.

Second, the study included only healthy, non-obese men. For this reason, the results cannot be generalized. The effects might be different in obese people or women.

The probiotic supplement also contained multiple strains of bacteria, which may have different effects on health. For this reason, it is unclear which probiotic bacteria were responsible for suppressing weight gain.

Bottom Line: This study was well designed and conducted. However, the number of participants was low and the findings may not apply to women or people with obesity.

Summary and Real-Life Application

This study evaluated whether probiotic supplements would help protect against the adverse effects of consuming a high-fat, high-calorie, weight-gain diet.

Neither the diet nor the probiotics had significant effects on insulin sensitivity or endotoxin levels.

The diet did cause an increase in one inflammatory marker, but the probiotics did not have any effect.

However, this study did show that people who took a probiotic supplement gained significantly less weight and fat mass. This indicates that probiotics may be an effective way to prevent weight gain and obesity.

Probiotics may even be useful for weight loss if the diet is not hypercaloric, but the current study did not test that.

Type of Dietary Fat May Affect Body Composition

The role of dietary fat in body fat distribution is not well known.

However, some interesting results from the LIPOGAIN study were published in the July, 2014 issue of Diabetes.

This study compared the effects of overfeeding saturated and polyunsaturated fat on fat accumulation and body composition.

Here is a detailed summary of the findings.

Background

Visceral fat accumulates in the abdominal cavity, around organs such as the intestines, liver and pancreas.

Conversely, ectopic fat accumulates inside the organs themselves, mainly the liver and pancreas.

Both visceral and ectopic fat are associated with an increased risk of chronic disease, such as heart disease and type 2 diabetes (123).

Combined, the adverse health consequences of visceral and ectopic fat are known as metabolic syndrome. For this reason, well-designed research on the causes of visceral and ectopic fat is extremely valuable.

Study Reviewed

A team of Swedish scientists set out to investigate the effects of eating high amounts of saturated fat and polyunsaturated fat on body composition and the accumulation of visceral and ectopic fat.

Overfeeding Polyunsaturated and Saturated Fat Causes Distinct Effects on Liver and Visceral Fat Accumulation in Humans.

Basic Study Design

This was a 7-week, double-blind, randomized, parallel-group trial in 39 young and normal-weight men and women.

The purpose of the study was to compare the effects of eating high amounts of either saturated fat or polyunsaturated fat.

Participants were randomly assigned to one of two groups:

  • Saturated fat group: Participants were overfed with muffins high in saturated fat for 7 weeks. The fat was in the form of refined palm oil, which is rich in palmitic acid, the most common saturated fat in the modern diet.
  • Polyunsaturated fat group: Participants were overfed with muffins high in omega-6 polyunsaturated fat for 7 weeks. The fat was in the form of refined sunflower oil, which is rich in linoleic acid.

The amount of muffins was adjusted so that each participant would achieve a 3% weight gain during the study period.

On average, the daily amount of oil added to the muffins was about 40 grams, and the calorie excess was 750 kcal per day.

The researchers measured total body fat, visceral fat, abdominal skin fat, liver fat, pancreatic fat and lean tissue.

Bottom Line: This study was a randomized controlled trial in healthy, normal-weight individuals. It compared the effects of overeating palm oil and sunflower oil on fat accumulation and body composition.

Finding 1: Fat Mass and Lean Mass Gain Were Affected

Participants in both groups gained equal amounts of weight, or 1.6 kg (3.5 lbs).

However, those who were fed saturated fat gained significantly more fat mass, whereas polyunsaturated fat led to a greater increase in lean mass.

In fact, the ratios of lean and fat tissue gain in the polyunsaturated and saturated fat groups were approximately 1:1 and 1:4, respectively.

The chart below shows changes in fat mass and lean mass in both groups.

This difference remained, even when total body water content was taken into account.

These findings are supported by previous studies, one in postmenopausal women and one in rats (45).

However, exactly how this works is unknown. It is also unclear what the current study’s increase in lean tissue actually represents or signifies.

Bottom Line: Eating high amounts of saturated fat caused more fat accumulation than eating polyunsaturated fat. Additionally, polyunsaturated fat appeared to cause a greater increase in lean mass.

Finding 2: Saturated Fat Caused More Visceral Fat Gain

There are two types of belly fat:

  • Subcutaneous: This type of belly fat is stored directly underneath the skin.
  • Visceral: This type of belly fat is stored inside the abdominal cavity, surrounding the intestines, liver and pancreas.

Visceral fat is much more harmful than subcutaneous fat, and is associated with various chronic diseases.

In the present study, participants who were fed saturated fat gained significantly more visceral fat, compared with those who got polyunsaturated fat. In fact, the difference was nearly two-fold.

The chart below shows the differences in visceral fat changes between groups.

These results suggest that overeating polyunsaturated fat may cause less fat accumulation in the abdominal cavity, compared to saturated fat.

That being said, overeating is still unhealthy, no matter what you are eating — overeating polyunsaturated fat just seems to be less bad.

Bottom Line: Eating high amounts of saturated fat from palm oil caused more visceral fat accumulation than eating polyunsaturated fat from sunflower oil.

Finding 3: Saturated Fat Caused More Liver Fat Gain

Participants who were overfed with saturated fat gained significantly more liver fat than those who ate polyunsaturated fat.

The chart below shows the differences in liver fat changes between groups.

These results are well supported by several other studies.

Observational studies have found high dietary intake of saturated fats, and low intake of polyunsaturated fats, to be associated with increased liver fat (678).

Fatty livers also contain low levels of polyunsaturated fat. Additionally, a clinical trial found that the polyunsaturated fat in sunflower oil reduced liver fat, compared to a diet rich in saturated fat (7910).

Accumulation of liver fat may lead to an adverse condition known as non-alcoholic fatty liver disease (NFLD). NFLD is present in up to 75% of obese people (11).

Fatty liver is believed to contribute to the development of many chronic diseases, such as type 2 diabetes and metabolic syndrome (1213141516).

Bottom Line: Eating high amounts of saturated fat from palm oil caused greater liver fat accumulation than eating polyunsaturated fat.

Finding 4: Pancreatic Fat Decreased in Both Groups

On average, pancreatic fat decreased by 31%. There was no significant difference between groups.

This unexpected finding cannot be explained based on the study’s results, and needs to be confirmed by other studies before any solid conclusions can be reached.

Bottom Line: Pancreatic fat decreased significantly in both groups. The finding needs to be confirmed in other studies before any conclusions can be made.

Limitations

This high-quality study appears to be well-designed and executed. Nevertheless, there are several limitations worth mentioning.

Sunflower Oil Contains More Vitamin E

Sunflower oil contains more vitamin E than palm oil, and vitamin E may reduce liver fat (17). However, the amount of vitamin E in the sunflower oil was probably too low to have any significant effects.

The Results May Not Be Generalized

The study tested palm oil and sunflower oil, and may not be generalized to all saturated or polyunsaturated fatty acids.

Other Nutrients May Play a Role

The dietary context may play an important role in how the body reacts to high amounts of fat.

The muffins provided to participants were also high in fructose and refined carbs, which could have affected the findings.

The Study Examined Only Lean Individuals

All study participants were lean, so the results may not apply to obese or diabetic individuals.

Bottom Line: The study was well designed and executed. There are a few limitations, so the results should not be generalized.

Summary and Real-Life Application

This study shows that dietary fat type may affect fat distribution and body composition.

To summarize the findings:

  • High amounts of palm oil (palmitic acid) led to greater liver and visceral fat gain, compared to sunflower oil.
  • High amounts of sunflower oil (linoleic acid) led to almost a three times greater increase in lean body mass, compared to palm oil.

Simply put, palm oil caused fat accumulation in places associated with adverse health outcomes. Conversely, sunflowers oil caused less fat gain overall and much greater gain in lean mass.

These results are of limited value for health-conscious consumers, since they may only apply to those that are overeating and gaining weight. However, a previous study showed a similar effect during a weight-maintenance diet (10).

That being said, this doesn’t necessarily mean that saturated fat is unhealthy, only that eating too much of it may have worse consequences compared to eating an equal amount of polyunsaturated fat. At least in the context of a high-calorie diet.

At the end of the day, overeating should be avoided and fat intake should be balanced.

Eating Less Sugar Has Multiple Health Benefits

Excessive fructose consumption is believed to be one of the main causes of metabolic syndrome.

Fructose makes up 50% of table sugar, which is the most commonly consumed sweetener in the world.

A recent study, published in Pediatric Obesity, investigated whether replacing sugar with starch would improve markers of metabolic syndrome in children.

Here is a detailed summary of the findings.

Background

Although metabolic syndrome is mainly associated with obesity, some normal-weight children have similar symptoms (1).

Additionally, type 2 diabetes is more common than obesity in Chinese and Indian children. This indicates that metabolic syndrome is not solely explained by excessive calorie intake (2).

In fact, one of the main suspects is fructose, a type of sugar found in virtually all sugar-sweetened foods.

Fructose has several properties that make it particularly unhealthy when eaten in high amounts:

  • Liver fat accumulation: Excessive intake leads to liver fat accumulation and increases the risk of non-alcoholic fatty liver disease (345).
  • Oxidative stress: Fructose increases oxidative stress, which may disrupt cellular function (6).
  • Overeating: Fructose does not suppress appetite as efficiently as glucose, and may therefore promote overeating (78).

For these reasons, limiting fructose from added sugars may have many health benefits.

Study Reviewed

Researches from California set out to investigate the metabolic effects of replacing sugar with starch for children with obesity and metabolic syndrome.

Isocaloric Fructose Restriction and Metabolic Improvement in Children with Obesity and Metabolic Syndrome.

Basic Study Design

This 9-day trial in 43 obese children with metabolic syndrome investigated the short-term health effects of reducing sugar and fructose.

The participants’ normal diets were characterized by high amounts of added sugar. Their average sugar intake was 28% of total calories.

To examine the effects of fructose restriction, the participants followed a weight-maintenance diet that reduced sugar and fructose to 10% and 4% of total calories, respectively, and replaced it with starch.

The diet contained similar proportions of protein, fat and carbs as their habitual diet before the study.

At the beginning and end of the study, the researchers measured body composition, blood sugar, insulin, blood pressure and blood lipids.

Bottom Line: This was a 9-day trial in obese children with metabolic syndrome. Its purpose was to examine the health effects of reducing dietary sugar and fructose and replacing it with starch.

Finding 1: Eating Less Fructose Improved Blood Pressure

During the study period, diastolic blood pressure decreased by 4.9 mmHg, on average.

Conversely, systolic blood pressure did not decrease significantly.

These results are supported by observational studies in children and adolescents that found an association between dietary fructose intake and both diastolic and systolic blood pressure (910).

Bottom Line: Reducing sugar intake significantly improved diastolic blood pressure, but not systolic blood pressure.

Finding 2: Less Dietary Sugar Improved Blood Lipids

The blood lipid profile also improved significantly during the study:

  • Fasting triglycerides: -46%.
  • LDL-cholesterol: -13%.

These findings are consistent with previous studies showing that high-fructose diets can have adverse effects on the blood lipid profile (1112).

Bottom Line: Eating less fructose improved the blood lipid profile, causing a significant reduction in fasting triglycerides and LDL-cholesterol.

Finding 3: Eating Less Sugar Improved Blood Sugar Control

Blood sugar control improved substantially during the course of the study:

  • Fasting blood sugar: -6%.
  • Fasting insulin: -53%.
  • Peak insulin: -56%.
  • Insulin resistance: -58%, according to HOMA-IR.

Also, the body’s response to glucose ingestion improved significantly, according to the results of an oral glucose tolerance test.

These improvements were not associated with either weight loss or a calorie deficit. This suggests that the benefits were mostly caused by the reduction in sugar intake.

Bottom Line: Reducing sugar intake improves blood sugar control, fasting blood sugar, fasting insulin and insulin resistance.

Finding 4: Eating Less Sugar Caused Weight Loss

During the study, body weight decreased by 1%, or 0.9 kg (2 lbs), on average.

Since the participants were supposed to have been on a weight-maintenance diet, the weight loss is probably not explained by substantial fat loss.

There are a few factors that likely contributed to the weight loss:

  • Reduced water retention: Less sugar intake may have decreased water retention. The weight loss took place in the first 4 days, suggesting loss of water weight.
  • Decreased lean mass: Lean mass decreased significantly, or by 0.6 kg (1.3 lbs). Since water weight is a part of the lean mass measurement, this further supports that the weight loss may have been due to reduced water retention.
  • Less food intake: 77% of the participants reported that they were unable to eat all of the food provided by the researchers. This may have led to weight loss. However, fat mass reduction was not significant, according to DXA.

Although most participants did lose weight, a total of 10 participants did not lose weight during the study. However, these participants still experienced health benefits similar to the children who did lose weight.

The researchers concluded that the health benefits seen in the present study could not be explained by the small amount of weight loss.

Bottom Line: Overall, the participants lost weight during the study. This weight loss may be largely attributed to less water retention.

Limitations

This was a well-designed and well-executed study. However, there were a few limitations.

By replacing sugar with starch and adding fiber, the overall glycemic index of the diet was reduced.

It is possible that some of the findings were, at least, partly caused by a reduction in the glycemic index of the diet, rather than a decrease in fructose (13).

Also, the study had no control group. For this reason, we do not know if other study-related factors had an effect.

Bottom Line: The study was designed well and there is no reason to doubt the results. The findings are also supported by previous studies.

Summary and Real-life Application

The study showed that eating less sugar has multiple health benefits.

In summary, reducing sugar and fructose intake:

  • Reduced blood pressure.
  • Lowered blood cholesterol.
  • Decreased triglyceride levels.
  • Improved blood sugar control.

These results happened in only 9 days. Restricting fructose for a longer period of time may have resulted in even greater health benefits.

Simply put, reducing your intake of added sugar is one of the best things you can do for your health.

Diet and Gut Microbiota in Inflammation and Disease

Emerging evidence links chronic intestinal inflammation with obesity and metabolic disorders like insulin resistance.

What’s more, this association seems to be affected by changes in the gut microbiota caused by diet.

Recently, a group of researchers summarized the available evidence in a review published in Cell Metabolism. Below is an overview of the review’s main points.

Article Reviewed

This article discusses the association of intestinal inflammation, obesity, metabolic syndrome, the gut microbiota and dietary factors.

The Intestinal Immune System in Obesity and Insulin Resistance.

What is Inflammation?

Inflammation is the immune system’s response to infection, injury or toxins. There are two types of inflammation: acute inflammation and chronic inflammation.

Acute inflammation

Acute inflammation starts immediately after an injury or infection.

Its purpose is to eliminate foreign substances or invaders, such as bacteria or viruses, as well as to remove dead or injured cells that are no longer functional.

Although it causes the swelling and redness associated with wounds and infections, it is an essential process that helps the body heal and protects it against further harm.

Chronic inflammation

Chronic inflammation lasts longer than acute inflammation. For this reason, it damages living tissue. This increases the risk of diseases like cancer, heart disease and type 2 diabetes.

Many conditions may lead to chronic inflammation, including infection, toxin exposure, autoimmune diseases, age, high blood sugar levels or an unhealthy diet.

Low-grade, chronic inflammation is an underlying condition in obesity, insulin resistance and many other conditions.

Bottom Line: There are two types of inflammation: acute and chronic. Acute inflammation is a beneficial process, while chronic inflammation is associated with obesity and metabolic diseases.

Obesity is Associated With Dysbiosis

Obesity and metabolic syndrome are associated with dysbiosis, a term that refers to an imbalance in the gut microbiota (1).

Some scientists even believe that dysbiosis plays a key role in the development of obesity.

This idea is supported by animal studies, showing that mice without any bacteria in their intestines had lower amounts of body fat, and did not become obese or insulin resistant when put on a high-fat diet.

However, when the intestines of these same mice were colonized by gut bacteria from normal mice, they started to gain fat and develop insulin resistance (23).

What’s more, intestinal bacteria from obese mice increased fat gain more than bacteria from lean mice (1).

Consistently, killing the intestinal bacteria of obese mice with an antibiotic treatment reduced body fat and improved insulin sensitivity (45).

However, obese people should not resort to taking antibiotics, as there are other, healthier approaches. Human studies have shown that weight loss may restore gut microbiota balance and improve metabolic health (67).

Bottom Line: Different types of bacteria are predominant in obese people’s guts. These bacteria make it easier for them to absorb calories and gain fat.

Dysbiosis May Cause Intestinal Inflammation

Studies indicate that obesity-associated dysbiosis may promote weight gain. This is because obese people may have greater numbers of bacteria that improve calorie absorption.

Dysbiosis also seems to be characterized by low numbers of beneficial, anti-inflammatory bacteria.

These bacteria feed on fiber, especially prebiotic fiber, and produce short-chain fatty acids like butyrate. Butyrate improves colon health and reduces inflammation.

For this reason, a lack of butyrate-producing bacteria may promote intestinal inflammation.

Transferring gut bacteria from lean, healthy donors to those with metabolic syndrome increased the butyrate-producing bacteria, which improved insulin sensitivity (8).

This also seems to be related to diet, in that obese people tend to have lower bacterial diversity and richness in their guts. However, one study showed that bacterial diversity can be restored by eating less (910).

Bottom Line: An imbalance in the microbiota of obese individuals may lead to intestinal inflammation. This imbalance is characterized by low numbers of beneficial, anti-inflammatory bacteria.

Dysbiosis May Weaken the Gut Wall

Intestinal permeability is an essential function of the gut wall. It allows nutrients to pass across the gut barrier into the blood circulation.

But the gut barrier should not be too permeable, since it needs to prevent potentially harmful substances from entering the body.

However, excessive intestinal permeability is an unfortunate consequence of dysbiosis and intestinal inflammation.

This leads to the leakage of bacteria or bacterial toxins across the gut barrier, worsening systemic inflammation and metabolic disease. This condition is called metabolic endotoxemia (41112).

Endotoxemia is associated with high calorie intake, high intake of saturated fat, abdominal obesity and an increased risk of diabetes (1314).

Conversely, getting enough fiber might help prevent endotoxemia by increasing the numbers of beneficial bacteria and strengthening the gut barrier (15).

Nevertheless, further studies are needed before any solid conclusions can be reached.

Bottom Line: Dysbiosis and intestinal inflammation may also increase intestinal permeability, allowing harmful substances to “leak” across the gut barrier. This may worsen inflammation and metabolic disorders.

Dietary Factors Affect Intestinal Inflammation

Intestinal inflammation is not only associated with dysbiosis and a “leaky gut.” All of this also appears to be linked to dietary habits.

Dietary factors that may worsen intestinal inflammation include:

  • A diet high in saturated fat: A diet high in saturated fat has been associated with intestinal inflammation in mice. This effect appears to be mediated by the gut microbiota, since bacteria-free mice showed no effects (161718).
  • Food emulsifiers: Another mouse study suggests that two commonly-used food emulsifiers may change the gut microbiota and worsen inflammation (19).

Other dietary factors may protect against inflammation:

  • Losing weight: One human study showed that losing weight reduced intestinal inflammation, while also improving blood sugar levels and blood lipids (20).
  • Omega-3 fatty acids: A study in mice found that saturated fats from lard increased inflammation, whereas polyunsaturated fats from fish oil protected against inflammation (16).
  • Probiotics: Several types of probiotic bacteria may reduce intestinal inflammation and strengthen the gut barrier (2122232425).
  • Antioxidants: Antioxidant polyphenols from fruits and vegetables may also reduce inflammation (26).
  • Prebiotic fiber: Eating plenty of prebiotic fiber encourages the growth of beneficial bacteria that produce anti-inflammatory short-chain fatty acids, such as butyrate (27).

Several studies have also examined the effects of anti-inflammatory drugs on intestinal inflammation and metabolic conditions.

Apart from reducing inflammation, anti-inflammatory drugs may improve insulin sensitivity, decrease fasting blood sugar, reduce endotoxemia and increase gut bacterial diversity, without any effects on body weight (282930).

Taken together, these findings support the idea that diet-induced inflammation plays a key role in the development of chronic diseases in obesity.

Bottom Line: Dietary factors may either worsen or improve intestinal inflammation. Many of these effects seem to be mediated by the gut microbiota.

Summary and Real-Life Application

Obesity and many metabolic disorders are associated with chronic intestinal inflammation. Dietary factors and the gut microbiota also play a key role.

Fortunately, dietary strategies may be able to prevent or reduce these problems. These strategies may also improve many obesity-related metabolic conditions, such as insulin resistance.

Effective strategies include losing weight, eating omega-3s, and taking prebiotic fiber and probiotics.

DASH Diet Lowers Inflammation and blood pressure


DASH stands for Dietary Approaches to Stop Hypertension.

The DASH diet is designed to reduce blood pressure and improve blood lipids.

It’s typically low in fat and relatively high in carbs, but it’s not clear what role these macronutrients play in the diet’s effectiveness.

For this reason, a group of researchers compared the effects of a higher-fat, lower-carb DASH diet to the conventional DASH diet.

Their results were recently published in the American Journal of Clinical Nutrition.

The DASH diet focuses on fruits, vegetables, whole grains and lean meats.

The diet was designed after researchers noticed that high blood pressure was much less common in those who followed a plant-based diet, such as vegans and vegetarians, than in meat eaters (56).

This led researchers to design a diet that provided liberal amounts of the nutrients that appeared to protect people against high blood pressure.

The result was the DASH diet, which is high in fruits and vegetables and contains some lean protein sources like chicken, fish and beans. The diet is low in red meat, salt, added sugars and fat.

It’s thought that one of the main reasons people with high blood pressure can benefit from this diet is because it reduces the amount of salt they’re eating.

The regular DASH diet program recommends that people eat no more than 2,300 mg of sodium per day (or 1 teaspoon), which is in line with most national guidelines.

The lower-salt version recommends that people eat no more than 1,500 mg of sodium per day (or 3/4 of a teaspoon).

Conclusion: The DASH diet was designed to reduce high blood pressure. It’s rich in fruits, vegetables and lean proteins, but it restricts red meat, salt, added sugars and fat.

Background

It is currently the world’s most popular diet aimed at lowering blood pressure and reducing the risk of heart disease.

The original DASH diet has the following characteristics (12):

  • High in fruits and vegetables.
  • High in whole grains and fiber.
  • Includes nuts, seeds and legumes several times weekly.
  • High in low-fat dairy products.
  • Relatively low in red meat, poultry and fish.
  • Low in saturated fat, cholesterol and sodium.
  • Relatively high in potassium, magnesium and calcium.
  • Relatively low in refined sugar.

A large, observational study, called the Nurses’ Health Study, found a DASH-type diet to be associated with a reduced risk of heart disease and stroke (3).

Some researchers believe that the DASH diet may reduce heart disease risk because of its low saturated fat content (45).

The DASH Diet Lowers Blood Pressure

Blood pressure is a measure of the force put on your blood vessels and organs as your blood passes through them. It’s counted in two numbers:

  • Systolic pressure: The pressure in your blood vessels when your heart beats.
  • Diastolic pressure: The pressure in your blood vessels between heartbeats, when your heart is at rest.

Normal blood pressure for adults is a systolic pressure below 120 mmHg and a diastolic pressure below 80 mmHg. This is normally written with the systolic pressure written above the diastolic pressure, like this: 120/80.

People with a blood pressure reading of 140/90 are considered to have high blood pressure.

Interestingly, the DASH diet has been shown to lower blood pressure in both healthy people and those who already have high blood pressure.

Furthermore, it achieved this even though people didn’t lose weight or restrict their salt intake (78).

However, when sodium intake was restricted, they found that the DASH diet lowered blood pressure even further. In fact, the greatest reductions in blood pressure were seen in people with the lowest intakes of salt (9).

These low-salt DASH diet results were most impressive in people who already had high blood pressure, reducing it by an average of 11 points. In people with normal blood pressure, it reduced blood pressure by three points (5).

This is in line with other studies that have found that restricting salt intake can reduce blood pressure, especially in those who have high blood pressure (10).

However, it’s important to note that a decrease in blood pressure does not always translate to a decreased risk of heart disease or death (11).

Conclusion: Following a DASH dietary pattern is effective at lowering blood pressure, especially in people who already have high blood pressure.

Can You Lose Weight on the DASH Diet?

Apples, Grapes, a Fork and a Knife on Scales

The DASH diet has been shown to reduce blood pressure, regardless of whether people lose weight or not.

However, if you already have high blood pressure, chances are you have been advised to lose weight.

This is because the more you weigh, the higher your blood pressure is likely to be (121314).

Additionally, losing weight has been shown to lower blood pressure (1516).

Some studies have shown that people can lose weight on the DASH diet (171819).

However, those who have lost weight on the DASH diet have been in a controlled calorie deficit, meaning they were told to eat fewer calories than they were using.

Given that the DASH diet cuts out lots of high-fat, sugary foods, people may find that they automatically reduce their calorie intake and lose weight. Other people may have to consciously restrict their intake (20).

Either way, if you want to lose weight on the DASH diet, you’ll still need to reduce your calorie intake so you’re taking in fewer calories than you are using up.

Conclusion: The DASH diet could help you lose weight. However, for weight loss to occur, you still have to make sure you’re eating fewer calories than you’re burning.

Other Potential Health Benefits

Salmon and Vegetables

It’s well documented that the DASH diet can help lower blood pressure. However, the diet has additional benefits.

Here are some recorded benefits of the DASH diet:

  • Decreases cancer risk: A recent review found that people following the DASH diet had a lower risk of some cancers, including colorectal and breast cancer (21).
  • Lowers metabolic syndrome risk: Some studies have shown that the DASH diet reduces your risk of developing metabolic syndrome by up to 81% (2223).
  • Lowers diabetes risk: Following the DASH diet has been linked to a lower risk of developing type 2 diabetes. Some studies have also shown that it can improve insulin resistance (2425).
  • Decreases heart disease risk: One recent review showed that in women, following a DASH-like diet was associated with a 20% lower risk of heart disease and a 29% lower risk of stroke (26).

Many of these protective effects have been attributed to the high fruit and vegetable content of the DASH diet. This is because, in general, eating more fruits and vegetables is linked to a reduced risk of disease (27282930).

Conclusion: A DASH dietary pattern could reduce your risk of some cancers, diabetes, heart disease and metabolic syndrome.

Does the DASH Diet Work for Everyone?

One of the key findings of DASH diet studies was that the greatest reductions in blood pressure were seen in those with the lowest intakes of salt.

While this is interesting, the benefits of salt restriction on health and lifespan are not clear cut. For people with high blood pressure, reducing salt intake has been shown to significantly affect blood pressure (6).

However, in people who have normal blood pressure, the effects of reducing salt intake are much smaller (10).

This could partly be explained by the theory that some people are “salt sensitive,” meaning some people are more sensitive to salt and that it has a greater effect on their blood pressure (31).

Conclusion: Lowering salt intake from very high levels is beneficial for most people. Further salt restriction, as advised on the DASH diet, may only be beneficial for people who are “salt sensitive” and have high blood pressure.

 

DASH Diet Foods Plus Dairy

Article Reviewed

A team of scientists from the Children’s Hospital Oakland Research Institute, in California, compared the effects of the standard DASH diet and a higher-fat, lower-carb DASH diet on blood pressure and blood lipids.

Comparison of the DASH (Dietary Approaches to Stop Hypertension) diet and a higher-fat DASH diet on blood pressure and lipids and lipoproteins: a randomized controlled trial.

Basic Study Design

This randomized, controlled trial examined the effects of a modified DASH diet and the standard DASH diet on blood pressure and blood lipids. The modified diet included more dairy fat and fewer carbs.

The participants were healthy men and women with systolic blood pressure less than 160 mm Hg, and diastolic blood pressure between 80 and 95 mm Hg.

The participants were assigned to three groups in random order:

  • Standard DASH diet: Participants followed the conventional DASH diet.
  • Higher-fat DASH diet: This diet included more dairy fat and less carbs, but was otherwise identical to the standard DASH diet.
  • Control diet: The control diet was designed to represent a normal Western diet.

In the higher-fat DASH diet, the saturated fat content was increased from 8% to 14% of daily calories. To keep the calorie content the same, the carb content was also reduced by 12% of daily calories.

Each of these diets lasted for 3 weeks. The study had a crossover design, meaning that all of the participants followed all three diets during different study periods, separated by a 2-week washout period.

At the beginning and end of each of the three diets, the researchers measured blood pressure, blood lipids, body weight and body fat.

A total of 36 participants completed the study.

Conclusion: This randomized, crossover trial examined the effects of a higher-fat, lower-carb DASH diet on blood pressure and blood lipids.

Finding 1: Dairy Fat Did Not Adversely Affect Blood Pressure

Both the standard DASH diet and the higher-fat DASH diet reduced blood pressure to a similar extent, compared to the control diet, as shown in the chart below.

DASH Diets and Control Blood Pressure

However, blood pressure was significantly lower two weeks after the participants had finished the higher-fat DASH diet, suggesting delayed effects.

This means that eating more saturated dairy fat on the DASH diet does not adversely affect blood pressure.

Other studies have found that modifying the standard DASH diet by replacing carbs with unsaturated fat or protein yields similar or greater improvements in blood pressure (678).

Conclusion: The standard DASH diet and the higher-fat DASH diet reduced blood pressure to a similar extent, compared to the control diet.

Finding 2: Higher-Fat DASH Diet Reduced Triglycerides

The DASH diet and the higher-fat DASH diet had different effects on the blood lipid profile. The higher-fat DASH diet reduced the levels of triglycerides, as shown in the chart below.

DASH Diets and Control Triglycerides

This modest reduction in triglycerides may be explained by the lower amounts of carbs in the higher-fat DASH diet, compared to the standard DASH diet (9).

Conclusion: The higher-fat DASH diet reduced triglycerides, compared to the standard DASH diet, due to the lower carb content of the higher-fat diet.

Finding 3: Effects on LDL Peak Diameter

High levels of small, low-density lipoproteins (LDL) have been associated with an increased risk of heart disease (10).

In the present study, the conventional DASH diet reduced the peak diameter of the LDL particles, but the higher-fat DASH diet increased the peak diameter, compared to the control diet.

DASH Diets and Control LDL Peak

This means that the higher-fat DASH diet may have caused a modest increase in LDL particle size.

In fact, there was a trend for higher levels of large LDL particles with the higher-fat DASH diet, but the findings were not significant.

Previous studies have shown that reduced carb and sugar intake may cause a shift from smaller to larger LDL particles, explaining the present findings (1112).

Conclusion: The higher-fat DASH diet increased LDL peak diameter, whereas the standard DASH reduced the LDL peak diameter. Large LDL size has been associated with a reduced risk of heart disease.

Finding 4: No Increase in LDL-Cholesterol

The higher-fat DASH diet did not increase levels of LDL-cholesterol, compared to the standard DASH diet.

This is inconsistent with studies showing that replacing carbs or unsaturated fats with saturated fats increases LDL-cholesterol (913).

The authors speculate that the DASH diet may have characteristics that prevent the rise in LDL-cholesterol typically associated with a higher intake of saturated fats.

Conclusion: The higher-fat DASH diet did not increase LDL-cholesterol, compared to the standard DASH.

Limitations

This study appears to have been designed and implemented well.

It was a crossover trial, meaning that all participants were on all three diets during different study periods, separated by a 2-week washout period.

The purpose of the washout period was to prevent the previous diet from affecting the results of the next diet.

This washout, however, doesn’t appear to have worked in all cases, since there were some prolonged effects of the higher-fat DASH diet on blood pressure. The reason for this is unexplained.

Other limitations include a small number of participants and a relatively short study period.

Conclusion: This study did not have any serious limitations. However, the 2-week washout period between diets may not have been long enough with respect to blood pressure.

How to Make Your Diet More DASH-Like

Because there are no set foods on the DASH diet, you can adapt your current diet to the DASH guidelines by doing the following:

  • Eat more vegetables and fruits.
  • Swap refined grains for whole grains.
  • Choose fat-free or low-fat dairy products.
  • Choose lean protein sources like fish, poultry and beans.
  • Cook with vegetable oils.
  • Limit your intake of foods high in added sugars, like soda and candy.
  • Limit your intake of foods high in saturated fats like fatty meats, full-fat dairy and oils like coconut and palm oil.

Outside of measured fresh fruit juice portions, this diet recommends you stick to low-calorie drinks like water, tea and coffee.

Conclusion: It’s possible to adapt your current diet to align with the DASH diet. Simply eat more fruits and vegetables, choose low-fat products and lean proteins and limit your intake of processed, high-fat and sugary foods.

Frequently Asked Questions

If you’re thinking about trying the DASH approach for your blood pressure, then you might have a few questions about other aspects of your lifestyle.

The most commonly asked questions are addressed below.

Can I Drink Coffee on the DASH Diet?

Coffee in a Blue Cup

The DASH diet doesn’t prescribe specific guidelines for coffee. However, some people worry that caffeinated beverages like coffee may increase their blood pressure.

It’s well known that caffeine can cause a short-term increase in blood pressure (33).

Furthermore, this rise is greater in people with high blood pressure (3435).

However, a recent review found that despite coffee causing a short-term (1–3 hours) increase in blood pressure, it didn’t increase the long-term risk of high blood pressure or heart disease (33).

For most healthy people with normal blood pressure, 3–4 regular coffees per day are considered safe (36).

However, the slight rise in blood pressure (5–10 mm Hg) caused by caffeine means that people who already have high blood pressure probably need to be more careful with their coffee consumption.

Do I Need to Exercise on the DASH Diet?

The DASH diet has been shown to be even more effective at lowering blood pressure when people are also active (18).

Given the independent benefits of exercise on health, this is not surprising.

It’s recommended to do 30 minutes of moderate activity most days, and it’s important to choose something you enjoy, as you will be more likely to keep it up.

Examples of moderate activity include:

  • Walking (15 min/mile)
  • Running (10 min/mile)
  • Cycling (6 min/mile)
  • Swimming laps (20 mins)
  • Housework (60 mins)

Can I Drink Alcohol on the DASH Diet?

Glass of Red Wine

Drinking too much alcohol can increase your blood pressure (37).

In fact, regularly drinking more than three drinks per day has been linked to an increased risk of high blood pressure and heart disease (38).

On the DASH diet, it’s recommended that you drink alcohol sparingly and don’t exceed the national government guidelines — two or fewer drinks per day for men and one or fewer drinks per day for women.

: You can drink coffee and alcohol in moderation on the DASH diet. Combining the DASH diet with exercise may make it even more effective.

Summary and Real-Life Application

In short, this study shows that eating slightly more saturated dairy fat while on the DASH diet does not affect its beneficial effects on blood pressure.

Also, it did not have any adverse effects on the blood lipid profile.

A lower-carb, higher-fat DASH diet is a healthy, equally effective option, which may be easier to follow than the standard DASH diet.

For some people, the DASH diet may be easy to stick to and an effective way to reduce blood pressure.

However, it’s worth noting that reducing salt intake to 1,500 mg or less has not been linked to any hard health benefits, such as a reduced risk of heart disease or death, despite the fact that it can lower blood pressure.

Moreover, the DASH diet is very similar to the standard low-fat diet, which large controlled trials have not shown to reduce the risk of death (3940).

 

Dieting Increases Appetite More than Exercising

There are two basic weight loss methods: diet and exercise. When used separately, it’s unclear how these methods affect appetite.

For this reason, a team of scientists examined how diet and exercise affect appetite. Their results were recently published in the American Journal of Clinical Nutrition.

Background

Losing weight is hard. This is because your body doesn’t really want to lose weight, and uses several tricks to prevent this from happening.

One of them is to increase appetite and cravings to compensate for any lost weight.

However, previous studies suggest that losing weight by exercising may increase appetite and calorie intake less than dieting.

Several studies have also shown that calories lost via exercise are not completely restored by increased calorie intake afterward (123).

On the other hand, dieting seems to have much stronger effects on appetite and calorie intake (45).

Article Reviewed

A group of scientists compared the effects of calorie depletion by dieting or exercising on appetite and calorie intake.

Energy depletion by diet or aerobic exercise alone: impact of energy deficit modality on appetite parameters.

Study Design

The purpose of this small, randomized, crossover study was to examine the effects of dieting or exercising on appetite, appetite hormones and food intake.

A total of 10 healthy, young and relatively fit men participated in the study.

The study started with a control period, during which the participants followed a standardized diet for three days.

The participants were then assigned to two groups in a random order:

  • Dieting: During this three-day, calorie-reduced diet, the participants consumed 25% fewer calories than they needed to maintain stable body weight.
  • Exercising: For three days, the participants did aerobic exercise. The amount of exercise was carefully adjusted so that the participants would burn 25% of the calories they needed to maintain stable body weight.

Since this trial had a crossover design, all participants exercised and dieted on different occasions, separated by a 2-week washout period.

At the beginning and end of each of the three study periods, the researchers measured appetite hormones (ghrelin and leptin). Calorie intake and appetite were measured only at the end of each of the three study periods.

Bottom Line: This was a randomized, crossover study comparing the effects of dieting and exercising on appetite and calorie intake.

Finding 1: Dieting Promoted Greater Calorie Intake

Calorie intake increased significantly more after dieting, compared to exercising.

It was measured at a 30-minute buffet at the end of each of the three study periods. The findings are shown in the chart below.

Bottom Line: Calorie intake was significantly higher at the end of the dieting period, compared to both the control and exercising.

Finding 2: Dieting Led to a Greater Increase in Appetite

Dieting led to greater subjective ratings of appetite, compared to exercising, as assessed with a visual analogue scale (VAS) questionnaire.

Specifically, the ratings of “desire to eat”, “hunger” and “prospective food consumption” (PFC) were significantly higher after dieting.

The chart below shows the differences between groups.

However, there were no significant differences in appetite hormones between groups.

Bottom Line: Subjective ratings of appetite were significantly higher after the dieting period, compared to exercising.

Limitations

This study appears to have been well designed and implemented. However, a few limitations should be mentioned.

First, it was a small, pilot study with a limited statistical power. Second, the study was of short duration. The long-term effects of dieting and exercising may be different.

Finally, the participants were all young, relatively fit and healthy men. The results might not apply to other groups of people.

Bottom Line: The study’s main limitations were its small size and short duration.

Summary and Real-Life Application

This study showed that if you want to lose weight, dieting may increase appetite more than exercising, resulting in higher calorie intake to make up for the calorie deficit.

However, it would be difficult to imitate this study’s tightly controlled setting in a real-life situation.

Nevertheless, if you want to lose weight, exercise may make a difference.

Biggest Review Ever on Whole Grains and Blood Lipids

Whole grains have been considered to be healthy for a very long time.

Some of the health benefits of whole grains may be due to their effects on blood fats (cholesterol, triglycerides, etc).

However, the results of randomized controlled trials on the effect of whole grains on blood fats have been mixed (1).

Study Reviewed

A recent study assessed the effect of whole grains on blood fats by doing a meta-analysis, combining the results of many randomized controlled trials.

Hollander, et al. Whole-grain and blood lipid changes in apparently healthy adults: a systematic review and meta-analysis of randomized controlled studies. American Journal of Clinical Nutrition, 2015.

This study is the largest meta-analysis on the subject to date, and the only one that has distinguished between different grain types instead of just looking at “whole grains” as one big group.

Aim

The study aimed to assess the effect of whole grains on changes in blood fats, total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides.

Methods

The researchers searched the literature for randomized controlled trials.

They screened 6069 articles for eligibility and included those that fulfilled certain criteria.

These criteria included:

  • The study examined the effect of whole-grains, or diets rich in whole grains, on blood fats.
  • The control group had a diet low in, or without, whole grains.
  • The study focused on the grains themselves, not individual nutrients or dietary fiber.

Results

All in all, 24 randomized controlled trials with over 2275 participants were included.

Overall, the results of the analysis show that eating whole-grains causes the following changes in blood fats:

  • A decrease in LDL (“the bad”) cholesterol (Weighted difference: – 0.09 mmol/L or -3.48 mg/dL).
  • A decrease in total cholesterol (Weighted difference: -0.12 mmol/L or -4.68 mg/dL).
  • A non-significant tendency to decrease triglycerides (Weighted difference: -0.04 mmol/L or -3.54 mg/dL).
  • No change in HDL (“the good”) cholesterol.

When grain types were looked at individually, oats were responsible for most of the changes.

In comparison, other types of whole-grains had smaller or no significant effects.

Although eating whole grain oats was associated with a benefit, the study did not find a dose-response relationship, indicating that more is not necessarily better.

These results may be caused by the viscous beta-glucan fibers in oats, which have been shown to decrease total and LDL cholesterol in blood (2).

Barley and rye are also high in viscous fibers, such as beta-glucans. However, it was not possible to make any conclusions about barley and rye because of the few studies available.

Conclusions

The main conclusions of the study are:

  • Eating oats may reduce the risk of heart disease by improving the composition of blood fats.
  • In healthy people, other types of whole grains have smaller or no effects. It is not possible to draw conclusions about rye and barley due to a limited number of studies.

Limitations

This study only looked at the effects of whole grains in healthy adults. It is possible that they would have stronger effects in people with metabolic syndrome or a poor blood fat profile.

The study only looked at cholesterol, not lipoprotein markers like Apolipoprotein B or Apolipoprotein A1. These markers are more accurate predictors of cardiovascular risk than what was measured in the study.

Also, the study only looked at blood fats. It does not look at other health benefits of whole grains, such as blood sugar control, inflammatory markers or effects on weight loss.

What Do Other Studies Say?

The current study is the only meta-analysis that has investigated the effects of different whole grains on blood fats in a dose-dependent manner.

One other meta-analysis has examined similar studies, but it did not include as many studies as the current meta-analysis (3).

The results of that study were similar. It found that oats caused significant reductions in total cholesterol and LDL-cholesterol.

Real Life Applications

The blood-lipid lowering effects of whole grains are smaller than those achieved with medications.

Nevertheless, the effects are considered clinically relevant. This is particularly true of whole-grain oats.

Whole-grain oats can be recommended as a part of a heart-healthy diet, but the current evidence on other types of whole grains and blood fats is not impressive.

High Intensity Interval Training may reverse aging


It’s long been known that physical activity can reduce inflammation in your body and improve heart health.

This study recently published in cell.com shows that High-intensity interval training (HIIT) is more effective than weight training or cardio for improving metabolic health, is superior for fighting age related decline, and may yield anti-aging benefits down to the cellular level.

HIIT was found to be even more effective at improving mitochondria biogenesis in older individuals.

“HIIT reversed many age-related differ- ences in the proteome, particularly of mitochondrial proteins in concert with increased mitochondrial pro- tein synthesis.”

“HIIT increased maximal absolute mitochondrial respiration in young (+49%) and older adults (+69%), whereas a significant increase following CT was observed in young (+38%), but not older adults”

“HIIT training in older adults had strong effect sizes in multiple outcomes, including mitochondrial respiration (1.7), aerobic fitness (0.99), insulin sensitivity (0.5)”

“HIIT revealed a more robust increase in gene transcripts than other exercise modalities, particularly in older adults, although little overlap with corresponding individual protein abundance was noted.”

Researchers enrolled 36 men and 36 women from two age groups—either under 30 or over 65.

They took on three different exercise programs that included high-intensity interval biking, strength training with weights, and one that mixed lighter cycling and lifting. Each group completed their plan for 12 weeks.

“Any exercise is better than being sedentary,” said Dr. Sreekumaran Nair, senior author of the study and a diabetes researcher at the Mayo Clinic in Rochester, Minnesota. However, Nair noted that high-intensity interval training (HIIT), in particular, is “highly efficient” when it comes to reversing many age-related changes.

Young and old, men and women

For the National Institutes of Health-funded study, Nair and his colleagues enlisted the help of both men and women from two age groups: The “young” volunteers ranged in age from 18 to 30; “older” volunteers ranged in age between 65 and 80. Next, the researchers divided these participants into three mixed-age groups and assigned each a different supervised exercise training program lasting three months.

The high-intensity interval training training group did three days a week of cycling, with high-intensity bouts sandwiched between low-intensity pedaling, and two days a week of moderately difficult treadmill walking.

The strength training group performed repetitions targeting both lower and upper body muscles just two days each week.Finally, the combined training group cycled (less strenuously than the first group) and lifted weights (fewer repetitions than the second group) for a total of five days a week.

There were clear differences, then, in the amount of time different participants spent in the gym.

Before and after each training session, the researchers assessed various aspects of each volunteer’s physiology, including body mass index, quantity of lean muscle mass and insulin sensitivity, one indication of diabetes.

The researchers also did routine biopsies of each volunteer’s thigh muscles and performed a biochemical analysis in order to establish a comprehensive fingerprint of the muscle.

Analyzing the gathered data, Nair and his colleagues found that all forms of exercise improved overall fitness, as measured by cardiorespiration, and increased insulin sensitivity, which translates into a lower likelihood of developing diabetes.

Although all exercise helped with musculature, strength training was most effective for building muscle mass and for improving strength, which typically declines with age.

Meanwhile, at the cellular level, high-intensity interval training yielded the biggest benefits.

With HIIT, younger participants saw a 49% increase, while older participants saw a 69% increase in mitochondrial capacity.

Every cell in our bodies contain   mitochondria. They perform as tiny batteries do, producing much-needed energy that powers everything your cells do.

Interval training also improved volunteers’ insulin sensitivity more than other forms of exercise. Drilling down deeper, Nair and his colleagues compared the protein-level data gathered from participants to understand why exercise provided these benefits.

Enhancing your cellular machinery

If we think of the cell as a corporate hierarchy, genes (DNA) are the executives issuing orders to their middle managers: messenger RNA. Tasked with transcribing this order, the RNA turns to ribosomes, which perform a supervisory role by linking amino acids in order to assemble protein molecules. Finally, the proteins, cellular work horses, carry out the task originally dictated by the gene.

“Proteins sustain environmental damage and the damaged proteins have to be … replaced with newly synthesized (produced) proteins,” explained Nair in an email. “With aging in sedentary people, production of many protein molecules decline. … Gradually the quantity of these protein molecules decrease causing functional decline.”

Analyzing the muscle biopsies, the researchers discovered that exercise boosts cellular production of mitochondrial proteins and the proteins responsible for muscle growth.

“Exercise training, especially high intensity interval training, enhanced the machinery (ribosomes) to produce proteins, increased the production of proteins and enhanced protein abundance in muscle,” Nair said.

He said the results also showed that “the substantial increase in mitochondrial function that occurred, especially in the older people, is due to increase in protein abundance of muscle.”

In some cases, the high-intensity regimen actually seemed to reverse the age-related decline in both mitochondrial function and muscle-building proteins.

Exercise’s ability to transform mitochondria could explain why it benefits our health in so many different ways, according to the authors.

Muscle cells, like brain and heart cells, are unusual in that they divide only rarely compared with most cells in the body. Because muscle, brain and heart cells do wear out yet are not easily replaced, the function of all three of these tissues are known to decline with age, noted Nair.

If exercise restores or prevents deterioration of mitochondria and ribosomes in muscle cells, exercise possibly performs the same magic in other tissues, too. And, although it is important simply to understand how exercise impacts the mechanics of cells, these insights may also allow researchers “to develop targeted drugs to achieve some of the benefits that we derive from the exercise in people who cannot exercise,” Nair said.

‘Almost a medicine’

According to Jennifer Trilk, an assistant professor of physiology and exercise science at University of South Carolina School of Medicine Greenville, the new study is comprehensive and supports previous research, combining it all into one paper.

“We cannot have enough studies surrounding this information because of how impactful it is for health,” said Trilk, who was not involved in the research

She explained that if younger people boost mitochondrial function when they’re young, they would be preventing disease, while for an older population, they would also be preventing disease while maintaining skeletal muscle, which wanes in older age.

“Mitochondrial function is important to almost every cell in the human body,” Trilk said. “So when you don’t have mitochondrial function or when you have mitochondrial dysfunction, you have dysfunction of cells, so from a molecular standpoint, you start seeing cellular dysfunction years before you start seeing the global effect, which ends up coming out as symptoms of diseases: diabetes, cancers and cardiovascular disease.”

Juleen Zierath, a professor of integrative physiology at Karolinska Institutet in Stockholm, Sweden, finds the study to be “a really comprehensive and thorough analysis of human skeletal muscle before and after” adapting to different exercise regimens. Zierath, who did not participate as a researcher in the current study, also appreciated the fact that the authors comprehensively examined the effects on both younger and older participants.

“It teases out some of the training regimes that might be leading to greater effects on what they call mitochondrial fitness,” she said. Compared with the other two exercise programs, interval training “really had a more robust effect” on the machinery of cells, she said.

“It boosted the proteins that are important for mitochondrial function — the oxygen powerhouse of the cells,” Zierath said. “It reversed many of what we call age-related differences in mitochondrial function and oxidative metabolism.”

“Part of what happens with HIIT is, you disturb homeostasis, you exercise at a really high level, and the body needs to cope with that,” she explained.

Even though one program had superior effects, “every single exercise protocol they tested had positive effects,” said Zierath, who is looking forward to future research in this vein.

“Exercise is almost a medicine in some respects,” Zierath said. “It’s never too late to start exercising.”

Effects of Saturated Fat From Meat and Cheese on Blood Lipids

Heart disease is the leading cause of death in many countries, and high saturated fat intake has long been thought to be a major risk factor.

For this reason, health authorities have recommended limiting the intake of foods rich in saturated fat, such as meat and high-fat cheese. Alli (Orlistat) blocks fat absorption in the intestines.

However, studies indicate that high-fat cheese may actually protect against heart disease (123).

Additionally, several recent meta-analyses have been unable to find a link between saturated fat consumption and heart disease (45). However, there may be a small reduction in cardiovascular “events” when replaced with polyunsaturated fat (6).

Close Up of Woman Slicing Cheese

Study Reviewed

This randomized crossover trial examined how saturated fat from meat and cheese affected blood lipids.

Thorning et al. Diets With High-Fat Cheese, High-Fat Meat, or Carbohydrate on Cardiovascular Risk Markers in Overweight Postmenopausal Women: A Randomized Crossover Trial. American Journal of Clinical Nutrition 2015.

Aim

This study compared the effects of saturated animal fats and carbohydrates on blood lipids, apolipoproteins and fat digestibility.

Study Design

This 10-week study was a randomized crossover trial. A total of 19 postmenopausal women were recruited to participate.

Each participant’s energy requirements were calculated. Based on that, they were placed on a weight-maintenance diet to prevent weight gain during the study period.

The participants were then randomly assigned to one of three diets, each of which lasted for two weeks.

  1. High-cheese diet: This diet focused on cheese, but no other dairy products were included.
  2. High-meat diet: Participants on this diet were fed beef and pork, but no dairy products or probiotics.
  3. Control diet: The control diet contained high amounts of carbs and low amounts of fat, as well as protein from lean meat. The carbs mainly consisted of applesauce, white bread, pasta, marmalade, rice, cakes, biscuits and chocolate.

These three groups were isocaloric, meaning they had an equal energy content. Fiber was not specifically monitored. In the high-cheese and high-meat groups, the percentage of energy provided was:

  • Protein: 15%.
  • Fat: 35% (13% from saturated fat).
  • Carbs: 50%.

In the control diet, the percentage of energy provided was approximately:

  • Protein: 15%.
  • Fat: 25%.
  • Carbs: 60%.

All three diets contained similar amounts of protein. The only difference was the source of fat — from cheese or meat — and the amount of fat, which differed between the high-fat/high-meat diets and the control diet.

Since this was a crossover trial, all participants received each of the test foods at different points during the study. However, the order in which they got the foods was randomized.

Additionally, due to the nature of the diets, it was impossible to blind the participants.

Each of the study cycles was separated by a 2-week period, to stabilize blood lipids between diets.

At the beginning and end of each study period, blood samples were taken after a 12-hour fast. Fat digestibility was estimated by measuring fat in stools.

Results

A total of 5 participants dropped out during the study period, and 14 completed it.

Compared to the control diet, both the high-cheese and high-meat diets increased levels of the “good” HDL-cholesterol by 5% and 8%, respectively.

Apolipoprotein A-1 levels also increased by 8% and 4%, respectively. Apolipoprotein A-1 is the protein that carries HDL cholesterol in the blood, and having higher levels is a good thing.

In the high-cheese diet, the ratio of apolipoprotein B and apolipoprotein A-1 also went down by 5%, which indicates reduced heart disease risk.

Total cholesterol, LDL cholesterol, apolipoprotein B and triglycerides remained similar between groups.

Additionally, the fat in cheese did not seem to be efficiently absorbed.

Main Conclusions

The saturated fat in meat and cheese did not have adverse effects on blood sugar, compared to a high-carb, low-fat diet.

The study also found that some of the fat in cheese is not digested, and passes out of the body with feces.

Limitations

This study was well-designed and does not have any apparent shortcomings.

However, it has several limitations.

  1. There were only 14 participants that completed the study.
  2. The duration of the study was short.
  3. The participant group was very specific — postmenopausal women.
  4. Macronutrients were closely matched between diets, so the study does not provide a direct comparison of either cheese or meat as a whole.
  5. There was not a direct comparison of the different saturated fats found in cheese and meat. However, isolating these fats would neglect the potential interaction of the different nutrients in whole foods.

What Do Other Studies Say?

A high-fat diet rich in dairy calcium significantly decreased LDL-cholesterol, compared to a low-calcium diet (7).

Contrasting the results of the current study, other studies have shown a reduction in HDL-cholesterol and apolipoprotein A-1 when saturated fat has been replaced with carbs (89).

Supporting the results, a few observational studies have found a positive association between cheese intake and levels of HDL-cholesterol and apo A-1 (1011).

Summary and Real Life Application

For some time, health authorities have been recommending low-fat diets, saying that saturated fat increases the risk of heart disease.

However, the findings of this study (and many others) contradict those sources.

At the end of the day, saturated fat isn’t the demon it has been made out to be.

There is no reason to avoid saturated fat from whole foods, but there is no reason to glorify it and eat much of it either. It is neither good or bad, just neutral.

Tip: Nicotinamide Riboside can also lower risk of heart disease.

Low-Carb vs High-Carb For Type 2 Diabetes

Type 2 diabetes is a common condition characterized by high levels of blood sugar, usually due to insulin resistance.

The treatment of type 2 diabetes involves medication, but lifestyle strategies to lower blood sugar levels are very important as well.

These include increased exercise, weight loss and diet management (1).

Although low-carb diets have become popular for managing type 2 diabetes, few high-quality studies have investigated their long-term effects on blood sugar control and risk factors for heart disease (2).

Article Reviewed

A team of Australian researchers set out to compare the long-term health effects of a low-carb diet and a high-carb diet, focusing on differences in blood sugar control and risk factors for heart disease.

Tay et al. Comparison of Low- and High-Carbohydrate Diets for Type 2 Diabetes Management: A Randomized Trial. American Journal of Clinical Nutrition 2015.

Study Design

This was a randomized trial that spanned one year, or 52 weeks total.

A total of 115 obese and overweight adults with type 2 diabetes participated. Their age ranged from 35 to 68 years.

The participants were randomly assigned to one of two diets that contained an equal amount of calories:

  • Low-carb diet (LC): Carbs, protein and fat comprised 14%, 28% and 58% of calories, respectively. The total carb content was under 50 grams per day.
  • High-carb diet (HC): Carbs, protein and fat comprised 53%, 17% and 30% of calories, respectively.

Both diets restricted calories in order to produce weight loss. Calories were restricted by 30%, which amounted to 500–1000 calories, depending on the individual.

Tip:
Probiotics can help weight loss although the exact mechanism is unclear. Adding fiber can also help. Glucomannan is a favorite.

The fat content of the diets was mainly unsaturated, with less than 10% of calories from saturated fats.

In addition, all participants had 60-minute, supervised exercise sessions three times per week. These sessions focused on moderate-intensity aerobic and resistance exercise.

Blood samples were taken at the beginning, in the middle (24 weeks), and at the end (52 weeks) of the study.

Results

78 people completed the study, which is 68% of participants.

Due to regular exercise and the reduction of calories, participants in both groups lost weight and achieved significant health improvements.

This graph shows the weight changes in the two groups:

Changes in the following health markers were similar between groups:

  • Weight loss: The LC group lost 9.8 kg (21.6 lbs) and the HC group lost 10.1 kg (22.3 lbs).
  • HbA1c: Levels dropped by 1% in both groups.
  • Fasting blood sugar: Decreased by 0.7 mmol/L (27.02 mg/dL) in the LC group and 1.5 mmol/L (57.9 mg/dL) in the HC group.
  • LDL cholesterol: Levels dropped by 0.1 mmol/L (3.9 mg/dL) in the LC group and 0.2 mmol/L (7.7 mg/dL) in the HC group.
  • Blood pressure: Fell by 7.1 mmHg in the LC group and 5.8 mmHg in the HC group.
  • Inflammation: Estimated by the C-reactive protein, this decreased by 0.9 mg/L in the LC group and 1.2 mg/L in the HC group.
  • Insulin resistance: Also decreased substantially.

However, the low-carb group experienced significantly greater improvements in several health markers.

These included improvements in the following:

  • Medication: Greater reduction in the need for diabetes medication.
  • Glycemic variability: At least twice the decrease in glycemic variability, indicating greater stability in blood sugar levels.
  • Hyperglycemia: Less risk of experiencing high blood sugar levels.
  • Triglycerides: 0.4 mmol/L (7.2 mg/dl) reduction in triglycerides, versus a 0.01 mmol/L (0.18 mg/dl) reduction in the HC group.
  • HDL cholesterol: Increases of 0.1 mmol/L (1.8 mg/dl), versus 0.06 mmol/L (1.08 mg/dl) in the HC group.

Main Conclusions

For overweight or obese people with type 2 diabetes, calorie-restricted diets and regular exercise lead to weight loss, improved blood sugar control and reduced risk factors for heart disease.

This happens regardless of whether people follow low-carb or high-carb diets.

However, low-carb diets lead to greater improvements in blood sugar control and blood lipid profile than high-carb diets.

Additionally, low-carb diets decrease the need for diabetes medication and help stabilize blood sugar levels.

For this reason, low-carb diets can help effectively manage type 2 diabetes.

Limitations

This study was well designed, but had a few limitations.

  1. It did not include a control group of participants who did not change their diet, which would have helped isolate the effects of the lifestyle modifications.
  2. The assignment to diets was not blind.
  3. The LC group’s protein intake was much higher. Protein can affect weight loss as well as glycemic control, so this may have impacted the results of the study.
  4. By the end of the study, the LC group had increased their carbohydrate intake to 74 g, and saturated fat accounted for 11% of calories. Calorie intake was increased throughout the study in both groups.
  5. Adherence to the diet was good but not perfect, which is a common limitation of these types of studies.

What Do Other Studies Say?

HbA1c

The main outcome variable of the current study was HbA1c.

HbA1c is also known as glycated hemoglobin. Measuring HbA1c gives clinicians and scientists an idea of the average blood sugar levels over the previous few months.

High HbA1c levels are associated with an increased risk of developing diabetes-related complications.

Some studies have found no significant differences in the effects of low- and high-carb diets on HbA1c (34). Conversely, other studies have reported greater reductions in HbA1c with LC diets (567).

Weight Loss

Studies that have compared LC diets with calorie-restricted HC diets among patients with type 2 diabetes have provided mixed results.

Some reported that LC diets caused greater weight loss (27).

In the current study, both diets contained the same amount of calories, and weight loss was similar.

This suggests that the main cause of weight loss is calorie deficit rather than the nutrient composition of the diets. Several previous studies support this (3489).

Blood Lipids

Supporting the present study, one 24-week randomized controlled trial in obese adults with type 2 diabetes showed that a LC diet caused greater improvements in blood sugar control and blood lipid profile than a HC diet (10).

Similarly, previous studies have reported greater reductions in triglycerides and higher increases in HDL-cholesterol with LC diets (1112).

In the current study, similar reductions in cholesterol were seen in both the LC and HC diets.

In contrast, large reviews of previous trials suggest that very LC diets may have less favorable effects on LDL cholesterol than conventional high-carb, low-fat diets (1314).

These differences may be explained by the type of fat replacing carbs in LC diets. In the present study, carbs were replaced with unsaturated fat, which may lower LDL-cholesterol.

Conversely, saturated fats may raise the levels of LDL-cholesterol (151617).

Summary and Real-Life Application

In conclusion, reducing calories and increasing exercise can lead to weight loss and improved health — regardless of whether people are on a low-carb or high-carb diet.

However, for obese people who have type 2 diabetes, a low-carb diet seems to be more effective at improving blood sugar control and reducing the risk factors for heart disease.

This is supported by several studies showing that low-carb diets are effective for diabetics.

Butter vs Cream – Not All Dairy Fat is Equal

Not all dairy fat is equal.

Sometimes the fat is enclosed in a layer called the milk fat globule membrane (MFGM), composed of phospholipids and protein.

The presence of MFGM may be the reason that the various dairy products have different effects on health.

Cream contains twice as much MFGM as butter, so researchers set out to study the health effects of these two dairy products.

Background and Introduction

Observational studies indicate that the relationship between dairy fat and heart disease depends on the type of dairy product consumed (123).

Supporting this, randomized controlled trials have found that butter raises cholesterol levels more than cheese, even though the fat content is equal (4567).

Most dairy fat is enclosed in a layer called the milk fat globule membrane (MFGM), which may be the cause of these differences. This membrane is primarily composed of phospholipids, but around 20% is protein (89).

Butter is an exception. When butter is produced, the churning process removes most of the MFGMs from the fat. In comparison, cream contains twice as much MFGM (8).

Bottom Line: Studies have indicated that different dairy products have varying effects on health markers, such as cholesterol levels. This may be due to the presence and quantity of MFGMs, which enclose the dairy fat.

Study Reviewed

Many years ago, scientists hypothesized that the presence of MFGMs may contribute to how dairy products affect several aspects of health (10).

Researchers at the Uppsala University Hospital in Sweden set out to test this hypothesis in a randomized controlled trial.

The results were recently published in the American Journal of Clinical Nutrition:

Potential of Milk Fat Globule Membrane in Modulation of Plasma Lipoproteins, Gene Expression, and Cholesterol Metabolism in Humans: A Randomized Study.

Here, we discuss the main results of this study and their relevance to human health.

Tip:
Products that block fat absorption can be helpful for weight loss, but eating more whole foods like or fermented foods with probiotics for weight loss is more effective long term

Basic Study Design

This was an 8-week, single-blind, randomized trial in healthy, overweight men and women. A total of 57 participants were recruited, but only 46 completed the study.

The participants were randomly assigned to one of two groups:

  1. Cream: Participants consumed 40 g of milk fat per day in the form of whipping cream, which is very high in MFGMs.
  2. Butter: Participants consumed 40 g of milk fat per day in the form of butter oil, containing virtually no MFGMs.

Additionally, the study examined the effects of the two diets on gene expression and markers of cholesterol formation and absorption.

The main research hypothesis was that milk fat enclosed in MFGMs, such as in cream, would raise cholesterol much less than fat without MFGMs.

Bottom Line: The study was a randomized trial. Participants were divided into two groups that received 40 g of milk fat. The only difference between groups was that the cream group got milk fat with MFGMs, but the butter group did not.

Finding 1: MFGMs in Dairy Fat Prevent an Increase in Cholesterol

The study confirmed the research hypothesis.

It clearly showed that butter increased the levels of blood cholesterol, whereas cream did not. These differences are likely caused by the presence of MFGMs in cream.

This chart shows how blood cholesterol rose in the butter and cream groups.

Here is an overview of how eating butter oil changed the levels of blood lipids and lipoproteins, compared to cream:

  • Total Cholesterol: +0.30 mmol/L compared to -0.04 mmol/L.
  • LDL-Cholesterol: +0.36 mmol/L compared to +0.04 mmol/L.
  • Ratio of Apolipoprotein B to Apolipoprotein A-I: +0.03 mmol/L compared to -0.05 mmol/L.
  • Non-HDL Cholesterol: +0.24 mmol/L compared to -0.14 mmol/L.

Butter caused a significant increase in all of these factors, which are known risk factors for heart disease (41112).

However, not all blood lipids were significantly different between groups. For example, there was no difference in HDL-cholesterol, triglycerides, LDL:HDL ratio and apolipoprotein A-I.

Additionally, body weight and body composition remained relatively constant during the study. Body weight decreased slightly in the butter group, but the change was not statistically significant.

Simply put, these results indicate that butter fat has adverse effects on the blood lipid profile, whereas cream fat does not.

Supporting these findings, several animal studies have also shown that MFGMs may counteract the rise in cholesterol caused by saturated fats (131415161718).

Conversely, human studies have provided conflicting results (192021).

However, unlike previous studies, the present study used whipping cream, containing intact MFGMs.

Bottom Line: Milk fat without MFGMs, such as butter, causes a rise in blood cholesterol. On the other hand, cream that contains MFGMs does not cause a significant increase in cholesterol.

Finding 2: MFGMs Appear to Change Gene Expression

How MFGMs moderate the effects of milk fat on blood lipids is unclear.

However, animal studies indicate that the MFGMs can lower blood cholesterol levels by changing gene expression in the liver (131415161718).

In the present study, gene expression was examined in 30 women, randomly selected from both groups.

The study found a significant group difference in the expression of 19 genes. The expression of all of these genes were increased in the MFGM group, but reduced in the butter oil group.

Although the function of most of these genes is not completely understood, some of them may be involved in the regulation of blood lipids.

In fact, changes in the expression of some of these genes were associated with increases in cholesterol.

Bottom Line: MFGMs may work by affecting gene expression, preventing a rise in cholesterol.

Finding 3: MFGMs May Reduce Cholesterol Absorption

In addition to changing gene expression, MFGMs may affect blood lipids by reducing cholesterol absorption in the digestive system.

This is supported by animal studies showing that sphingolipids or a mixture of milk phospholipids may reduce cholesterol absorption (1415161718).

The current study did not indicate any differences in cholesterol absorption between groups. However, the measurements were based on indirect markers for cholesterol absorption.

Bottom Line: Animal studies indicate that MFGMs may decrease cholesterol levels by reducing its absorption. The present study does not support this.

Discussion of Cream Consumption and Limitations of the Study

This study indicates that cream does not raise the levels of blood cholesterol.

However, this does not mean that cream should be consumed in high amounts. Cream is very rich in fat and calories, and may contribute to weight gain and obesity.

Tip:
A high carb diet can be just as bad as too much fat.

Being overweight is, in itself, a risk factor for heart disease and a variety of other chronic diseases.

Additionally, the results of the current study cannot be generalized. There are several reasons for this:

  • The participants consumed 40 grams of dairy fat per day, which is 10 grams higher than the national average in Sweden. Amounts higher than that may have adverse effects.
  • The study used whipping cream. Participants were not allowed to heat, mix or whip the cream. It is unclear what effects these preparation methods have on MFGMs.
  • The study used butter oil rather than butter. This is unlikely to be a limitation since the nutritional characteristics of these two products are very similar.

Bottom Line: Excessive consumption of cream may contribute to weight gain and obesity. However, low or moderate consumption is fine.

Summary and Real-Life Application

Not all high-fat dairy products have the same health effects.

Butter oil increases the levels of cholesterol in blood, whereas cream does not. This may be explained by MFGM, which surrounds the fat globules and counteracts the cholesterol-raising effects.

Simply put, cream appears to be healthier than butter because it contains MFGMs. How this affects hard endpoints, such as heart disease, remains to be seen.

Additionally, other studies on this topic have provided mixed results. Few have been conducted on specific dairy foods, so more research is needed before solid conclusions can be drawn.

That being said, no evidence justifies eating excessive amounts of cream. All high-fat dairy products should be eaten in moderation.

People with lipid problems or a family history of heart disease should probably minimize their consumption of butter. Extra virgin olive oil is a much better choice.

Tip:
High fiber consumption is a useful strategy for weight loss. Try Acacia Rigidula, or White Kidney Bean Extract if you’re not getting enough in your diet naturally. Try to eat Apples instead of applesauce, as it has far more fiber.

The Benefits of Vitamin D May Depend on Your Genes

Even though obesity has been associated with poor vitamin D status, the evidence that vitamin D affects obesity is not entirely conclusive (1).

For this reason, researchers set out to examine the effects of vitamin D supplements on body fat levels, insulin sensitivity and circulating vitamin D levels. They also looked at the effects of genetics on responses to vitamin D (2).

Here is a detailed summary of the results, recently published in the British Journal of Nutrition.

Background

Central obesity involves having a lot of fat around the waist. It is primarily caused by excessive belly fat, especially around the organs.

Central obesity has been associated with various chronic diseases, such as type 2 diabetes and heart disease.

Some people are more prone to central obesity than others, which may be partially explained by genetic factors.

Nutritional factors, such as poor vitamin D status, may also play a role (34567).

Study Reviewed

Iranian researchers examined the effects of daily vitamin D supplements on markers for central obesity. They also investigated whether these effects depended on individual genetic make-up.

Vitamin D receptor Cdx-2-dependent response of central obesity to vitamin D intake in the subjects with type 2 diabetes: a randomised clinical trial.

Basic Study Design

This was a 12-week, randomized trial in 60 Iranian men and women with type 2 diabetes. 88% of the participants were obese, while the rest were overweight.

Participants were randomly assigned to one of two groups:

  • Vitamin D group: Twice a day for 12 weeks, participants consumed a 250 ml yogurt drink fortified with 12.5 µg of vitamin D3.
  • Placebo group: The participants consumed the same yogurt drink, containing no vitamin D3.

At the beginning and the end of the study, the researchers measured body weight, total body fat, visceral fat, circulating vitamin D levels, fasting glucose, fasting insulin and HbA1c.

These values were then compared between groups.

In the second part of the study, the genetic make-up of participants in the vitamin D group was examined. This is discussed below.

Bottom Line: This was randomized trial in diabetic and overweight Iranian men and women. Participants were randomly assigned to receive vitamin D supplementation or a placebo.

Genotype Groups

genotype simply refers to the genetic make-up of each individual.

For example, when referring to individuals that have different variants of a specific gene, we talk about different genotypes.

The present study focused on variants of the Cdx-2 gene, which is associated with vitamin D function.

The participants were divided into three groups, depending on their genotype:

  • AA genotype: 52% had the AA variant of the Cdx-2 gene.
  • AG genotype: 32% had the AG variant of the Cdx-2 gene.
  • GG genotype: 16% had the GG variant of the Cdx-2 gene.

The benefits of vitamin D supplementation were then compared between genotypes.

Other studies have also examined the frequency of these genotypes, which appears to vary by race. For example, the AA genotype is found in 18% of South Asians, but only 4% of Europeans (89).

Bottom Line: The study divided the study participants into three groups based on genotype. The benefits of vitamin D supplementation were then compared between genotypes.

Finding 1: Vitamin D Levels Did Not Increase in All Genotypes

Overall, circulating vitamin D levels increased significantly in many of the participants who were given vitamin D supplements.

However, vitamin D levels did not increase for everyone receiving supplements.

They only rose significantly in people who had the AA genotype, or in about 52% of the participants in the vitamin D group. Vitamin D levels did not increase for people who had the AG or GG genotype.

The table below shows the rise in vitamin D between genotypes.

These results indicate that not all people benefit from vitamin D supplementation.

This unexpected finding needs to be confirmed by other studies before any solid conclusions can be reached.

Bottom Line: Vitamin D levels did not increase in all of those who were supplemented. In fact, they rose only in those who had the AA genotype.

Finding 2: Vitamin D Decreased Body Fat

In addition to weight loss, waist circumference, visceral fat, truncal fat and fat mass percentage all decreased more in the vitamin D group, compared to the placebo.

Additionally, within the vitamin D group, waist circumference, visceral fat, fat mass percentage and truncal fat decreased more in participants with the AA genotype.

The table below shows the difference in total fat loss percentage between genotypes.

These results indicate that supplementing with vitamin D may be a useful weight loss strategy, at least for some people.

Bottom Line: Supplementing with vitamin D reduced central obesity. However, this effect was only significant in participants with the AA genotype.

Finding 3: Vitamin D Improved Insulin Sensitivity

Insulin sensitivity increased significantly in the vitamin D group, compared with the placebo.

Within the vitamin D group, insulin sensitivity increased most among those with the AA genotype.

No significant differences were seen in other markers of blood sugar control.

Bottom Line: Vitamin D supplementation appears to improve insulin sensitivity, benefitting people with type 2 diabetes. These effects were more pronounced in participants with the AA genotype.

Limitations

This study appears to have been well-designed and executed.

However, some of the research methods were inaccurate. For example, the researchers used bioelectrical impedance analysis (BIA) to measure body fat.

BIA may underestimate body fat percentage as fat levels get higher (10).

The results also cannot be generalized to all people, since the participants were Iranian. These findings need to be confirmed in other racial groups.

Additionally, the participants were middle-aged and elderly, as well as diabetic and overweight or obese. Vitamin D supplementation may not have the same weight loss effects in healthy, young people.

Finally, the study period was only 12 weeks. Although this is a relatively long period for a randomized trial, a longer study might have told a different story.

Bottom Line: The study appears to have been well-designed and executed, although some of the methods were inaccurate. The results also may not be generalized to all people or supplementation time frames.

Summary and Real-Life Application

In short, this study shows that vitamin D supplementation can have many health benefits.

These include better vitamin D status, reduced fat mass and improved blood sugar control.

However, not all people benefit equally from vitamin D supplementation. The benefits appear to depend on people’s genes.

This reminds us that generalizing is not always appropriate in nutritional science. People sometimes react differently to what they are eating.

At the end of the day, vitamin D supplementation may provide many health benefits. The magnitude of these benefits varies, depending on people’s genetic make-up.

Low-Fat vs Low-Carb Diet: Which is More Effective?

A low-calorie, low-fat diet is frequently recommended for weight loss.

However, strong evidence suggests that low-carb diets may be more effective (12).

Recently, scientists set out to examine this issue further. They conducted a meta-analysis of randomized controlled trials that compared low-fat diets to low-carb diets.

Here, we provide a detailed summary of the main results.

Red Knife Slicing Bread Cheese

Background

Low-fat diets have traditionally been recommended for weight loss.

There are two reasons for this.

First off, fat is the most energy-dense macronutrient. Second, saturated fat used to be believed to increase the risk of heart disease (3).

However, many studies do not support the idea that low-fat diets are very effective for weight loss (456).

In fact, strong evidence points toward low-carb diets being more effective. These diets typically limit carbohydrate intake to less than 20–30% of total calorie intake, and are higher in protein and fat (78).

Study Reviewed

A group of US researchers compared the effectiveness of low-carb and low-fat diets on causing weight loss and improving risk factors for heart disease.

Dietary Intervention for Overweight and Obese Adults: Comparison of Low- Carbohydrate and Low-Fat Diets. A Meta-Analysis.

Basic Study Design

This was a meta-analysis of randomized controlled trials that compared the effectiveness of two weight loss diets: low-carb and low-fat.

The researchers selected 17 randomized controlled trials that included a total of 1797 overweight and obese participants.

These trials had a few things in common:

  • They ranged from 8 to 24 months in duration.
  • The low-carb diet contained less than 120 grams of carbs per day.
  • The low-fat diet contained less than 30% of calories from fat per day.

This analysis compared the effects of low-fat and low-carb diets on changes in body weight, lower blood sugar and blood pressure.

Bottom Line: This was a meta-analysis that combined the results of 17 randomized trials. These trials compared the effects of low-carb and low-fat diets on weight loss and risk factors for heart disease.

Finding 1: Low-Carb Diets Cause More Weight Loss

While both low-carb and low-fat diets may cause significant weight loss, low-carb diets seem to be more effective.

In fact, the probability of greater weight loss on a low-carb diet, compared to a low-fat diet, was more than 99%.

Tip: Most people on high carb diets tend to consume higher glycemic index foods which studies show are bad for weight loss and many health problems.

Avoid high glycemic foods like applesauce, and add more fiber to slow absorption to lower glycemic index. White Kidney Bean Extract and Konjac root are two excellent choices.

The chart below shows the difference in weight loss between groups.

Low Carb Low Fat on Weight and BMI

These findings are supported by previous studies on low-carb diets (8).

Part of the reason for this may be that low-carb diets also tend to be higher in protein than low-fat diets. Protein can have beneficial effects on body weight.

Bottom Line: Both low-fat and low-carb diets can help you lose weight, but people tend to lose more weight on low-carb diets.

Finding 2: Low-Carb Diets Are Better For Heart Health

Both diets reduced risk factors for heart disease.

Low-carb diets caused greater improvements in HDL-cholesterol and triglycerides, while low-fat diets affected total cholesterol and LDL-cholesterol more favorably.

The chart below shows the changes in blood lipids in both groups.

Low Carb Low Fat Changes

Additionally, improvements in systolic blood pressure were slightly better in the low-carb group, with a difference of 1.7 mmHg between groups.

The probability of a low-carb diet causing a greater reduction in heart disease risk was calculated as 98%.

Overall, these results are consistent with previous studies on low-carb diets (89).

Bottom Line: Low-carb diets caused greater improvements in several heart disease risk factors. The differences were modest, but statistically significant.

Limitations

This study appears to have been well-designed and followed a precise protocol.

However, there were a few limitations to the trials included in the analysis.

First, patient-level data was not available for all of the studies. This limited the researchers’ ability to fully evaluate the quality of the studies they used.

Second, a substantial amount of the studies’ participants dropped out, and the drop-out rate differed significantly between studies. However, according to analyses, this should not have affected the overall results.

Finally, the scores calculated for heart disease risk were based on assumptions that were not verifiable.

The study was supported by a grant from Atkins Nutritionals, a company that produces low-carb products. This does not invalidate the findings, but should be mentioned.

Bottom Line: This study was well-designed and followed a strict protocol. The limitations appear to be minimal.

Summary and Real-Life Application

In short, this study found low-carb diets to be more effective for weight loss than low-fat diets.

Additionally, low-carb diets appeared to be slightly better at improving blood lipids and blood pressure.

All that being said, the best diet for you is the one you can stick to in the long run. A low-carb diet can work very well, but only if you stick to it.

Tip: Garcinia Cambogia can help lower hunger and burn fat on any diet but is more effective on low fat diets. For those on high fat diets might respond better with Alli, as it blocks absorption of fat. Likewise, Lactobacillus Gasseri also blocks fat absorption which has been shown to help with losing weight and belly fat.

Do Red Meat and Processed Meat Really Cause Cancer?

Recently, the World Health Organization (WHO) released a summary saying red and processed meat cause cancer.

The media went ablaze, with headlines such as “Processed meat ranks alongside smoking as major cause of cancer, World Health Organisation says.”

However, this is an oversimplification of the results. In this review, we will explain the WHO’s findings in more detail.

Background and Summary Reviewed

The International Agency for Research on Cancer (IARC), which is a department within the WHO, assessed the effects of red meat and processed meat on cancer risk.

A short summary was released in Lancet Oncology, but the full results will be disclosed in volume 114 of the IARC Monographs.

The information that was published is not new. The link between these types of meat and cancer has been known for many years, although the strength of the evidence has been a matter of debate.

The reason for the media headlines now is the source of the claims. A warning issued by the WHO should not be taken lightly.

In this article, we are going to review the IARC’s research summary, discuss the strength of the evidence and look at what that means.

Bottom Line: The IARC (a division of the WHO) released a summary recently saying red and processed meat cause cancer. It gained a lot of media coverage.

What Did the Research Summary Say?

The summary paper refers to a massive study conducted by an international group of 22 scientists.

Here are their main conclusions:

  • Processed red meat is carcinogenic to humans: It is categorized as a “group 1” carcinogen, which means that the evidence linking processed meat with cancer is sufficient.
  • Red meat is probably carcinogenic to humans: It is categorized as a “group 2A” carcinogen, which means that the evidence is limited. Red meat has not yet been established as a cancer cause.

This mainly refers to colon cancer, which is the third main cause of cancer-related death in the US (1).

Processed meat was classified as a “group 1” carcinogen, the category of highest risk. Tobacco smoking and radioactive materials are in the same group.

However, this does not mean that processed meat is as carcinogenic as nuclear waste. The IARC classifications refer to the strength of the scientific evidence, not the level of risk.

In fact, the cancer risk of eating processed meat is very small compared to the risk associated with smoking.

Bottom Line: The study concluded that processed red meat can increase the risk of colon cancer in humans, whereas unprocessed red meat is only probably carcinogenic.

How Strong is the Evidence?

Randomized controlled trials, the gold standard of human research, are difficult when investigating the causes of cancer in humans.

There are two main reasons for this. First, cancer takes a very long time to develop. Second, exposing humans to something potentially carcinogenic is not ethically acceptable.

Therefore, we have to rely on observational evidence, animal studies and test-tube experiments. The IARC study analyzed more than 800 studies, most of which were observational in nature.

In observational studies, it is difficult to establish a causal relationship. There might be other unhealthy lifestyle habits related to processed meat intake that are responsible for the observed association.

However, the evidence linking processed meat and cancer is consistent across different populations, which makes the chance of bias less likely. It is also supported by animal and test-tube experiments.

According to IARC’s research summary, the evidence linking processed meat with cancer is sufficient.

Bottom Line: As evaluated by the IARC, there is sufficient evidence that processed meat increases the risk of colon cancer. There is no major reason to doubt their conclusion.

How is the Cancer Risk Increased?

It is not fully understood how red meat or processed meat increase cancer risk.

However, there are several plausible mechanisms. Below is an overview of the three main suspects.

N-Nitroso Compounds (NOCs)

High consumption of red meat and processed meat promotes the formation of N-nitroso compounds (NOCs) in the digestive system (2).

NOCs cause low-grade damage to the lining of the colon, which may increase the risk of cancer over time (34).

However, processed red meat is likely more harmful, as it contains chemicals that increase the formation of NOCs, especially when it is exposed to high heat (5).

Dietary fiber and chlorophyll, the green pigment in vegetables, may counteract this risk (67).

Heterocyclic Amines (HCAs)

Cooking meat at high temperatures leads to the formation of heterocyclic amines (HCAs) (8).

HCAs cause cancer in animals, and may possibly increase cancer risk in humans (9).

The risk of HCAs may be reduced by eating veggies, such as cruciferous vegetables, or marinating your meat with certain spices (1011).

Polycyclic Aromatic Hydrocarbons (PAHs)

High amounts of PAHs are formed when meat is cooked under high temperatures or smoked (12).

PAHs can damage the intestinal lining, but whether this happens after meat consumption in humans has not yet been investigated (13).

Bottom Line: High-temperature cooking promotes the formation of several carcinogenic substances, such as NOCs, HCAs and PAHs. Avoid charring your meat and use gentle cooking methods.

How Much Processed Meat Can You Safely Eat?

Conducting randomized controlled trials on meat and cancer is extremely difficult.

For this reason, we do not know exactly how much red meat or processed meat you can safely eat.

This probably depends on the individual and the dietary context.

Additionally, the effect is clearly dose-dependent, and excessive consumption of processed meat is risky.

One meta-analysis estimated that for every 50 grams of processed meat eaten per day, the risk of colon cancer increases by 18% (14).

Bottom Line: The amount of meat you can safely eat is unknown. However, the dose makes the poison, and eating high amounts of processed meat is not advised.

Some High-Quality Studies Disagree

All this being said, two long-term randomized controlled trials have examined the effects of a low-fat, high carb diets on the risk of cancer.

The participants in these studies changed many things at a time, including significantly reducing their consumption of processed meat and red meat.

These studies did not find a reduction in the risk of colon cancer (1516).

This indicates that the advice to “eat less processed and red meat” may not be very effective at preventing colon cancer in the real world, at least not when combined with a conventional low-fat diet.

Bottom Line: Two long-term randomized controlled trials on low-fat diets, with less processed meat and red meat, did not find a reduction in the risk of colon cancer.

Summary and Real-Life Application

In short, the IARC study concluded that eating high amounts of processed meat increases the risk of colon cancer.

Red meat, on the other hand, cannot be established as a cause of cancer. Yet, it was classified as a probable cause of cancer.

More evidence is needed on this subject. But for now, we can assume that it is best to limit the intake of processed meat.

On the other hand, it is clear that being overweight is a root cause of many diseases and health problems. Eating more protein is often an effective way to lose weight fast, and is much preferred over depending on fads like garcinia cambogia, or diet pills like alli.

If you’re going to eat red meat, then use gentler cooking methods and don’t burn or char your meat.

Tip:Adding some Glucomannan or Acacia Rigidula to your food is a great way to add some fiber to your diet, which has proven benefits at fighting cancer.

The Bioavailability of Vitamin E is Lower in Metabolic Syndrome

Metabolic syndrome affects 34.7% of Americans (1).

It is a collective term for several adverse health conditions commonly associated with abdominal obesity.

Studies suggest that people with metabolic syndrome have lower levels of antioxidants, such as vitamin E, but the reason is not entirely clear.

A recent study examined vitamin E bioavailability in people with metabolic syndrome.

Today’s review provides a detailed summary of its findings.

Foods-High-In-Vitamin-E

Background

Vitamin E is a group of fat-soluble antioxidants, also known as tocopherols and tocotrienols.

Only one of them — alpha-tocopherol — is thought to meet the body’s vitamin E requirements. In this review, alpha-tocopherol will simply be referred to as vitamin E.

Like other fat-soluble vitamins, vitamin E is believed to be better absorbed into the bloodstream when eaten with fat (2).

In the body, its strong antioxidant properties protect cell membranes from oxidative damage.

For this reason, the elevated oxidative stress and inflammation associated with metabolic syndrome may increase people’s vitamin E requirements (34).

Vitamin E levels are generally lower in people with metabolic syndrome, compared to healthy individuals (5).

Tip: Quercetin lowers inflammation in a similar manner, which can also help increase NAD+ levels that are now thought critical for healthy aging.

Oxidative stress and inflammation are believed to explain these low levels, but it’s unclear how metabolic syndrome affects vitamin E bioavailability or the proportion of active vitamin E entering the blood circulation.

Article Reviewed

This study examined the effects of metabolic syndrome and dairy fat on vitamin E bioavailability.

α-Tocopherol bioavailability is lower in adults with metabolic syndrome regardless of dairy fat co-ingestion: a randomized, double-blind, crossover trial.

Study Design

The purpose of this randomized, crossover trial was to examine vitamin E bioavailability in people with metabolic syndrome, compared to healthy people. It also examined whether dairy fat had any effects on its absorption.

A total of 20 men and women were recruited — 10 with metabolic syndrome and 10 healthy individuals. These two groups were age-matched and contained an equal number of men and women.

All participants received 15 mg of vitamin E on 4 separate study visits, each of which was separated by a 2-week washout period.

On each visit, the participants arrived at the research unit in the morning after an overnight fast and took the vitamin E supplement with 240 ml of milk.

The fat and carb content of the milk differed between visits, and on one occasion they got soy milk instead of cow’s milk, as shown in the chart below.

Fat-In-Non-Fat-Reduced-Whole-And-Soy-Milk

All of the participants were provided with standardized food three days prior to, as well as during the first 24 hours of, each study visit.

Throughout each study visit, which lasted for 72 hours, the researchers collected blood at regular intervals. They then measured various blood variables, including vitamin E and C, blood sugar levels and inflammatory markers.

Researchers also conducted a test-tube experiment, examining the effect of dairy fat on the potential absorbability of low (15 mg) and high (268 mg) doses of vitamin E.

Bottom Line: This was a randomized, crossover trial investigating the bioavailability of vitamin E in people with metabolic syndrome. It also examined the effects of dairy fat on vitamin E bioavailability.

Finding 1: Metabolic Syndrome Was Associated with Lower Vitamin E Levels

At the start of the study, circulating levels of vitamin E were similar between healthy participants and those with metabolic syndrome.

However, when vitamin E levels were corrected for plasma total lipids (µmol/mmol lipid) as recommended, the levels were lower in participants with metabolic syndrome, compared to those who were healthy (6).

These findings are shown in the chart below.

Vitamin-E-Metabolic-Syndrome-Vs-Healthy

The results are supported by previous studies (5).

The lower levels of vitamin E may be explained by the chronic inflammation and oxidative stress associated with metabolic syndrome.

Accordingly, the study showed that participants with metabolic syndrome had higher levels of oxidized low-density lipoprotein (O-LDL), a marker of oxidative stress, and lower levels of vitamin C compared to healthy participants.

OLDL-And-Vitamin-C-Metabolic-Syndrome-Vs-Healthy

They also had higher levels of the inflammatory markers, interleukin-6 (IL-6), interleukin-10 (IL-10) and C-reactive protein (CRP), as shown below.

IL-6-10-And-CRP-Metabolic-Syndrome-Vs-Healthy

High levels of oxidized LDL and inflammatory markers were associated with lower levels of vitamin E.

Yet, vitamin E depletion was slower in participants with metabolic syndrome, compared to those who were healthy.

Slower vitamin E depletion may indicate lower requirements, but vitamin E metabolism is likely more complicated than that.

Bottom Line: People with metabolic syndrome had lower circulating levels of vitamin E, compared to healthy individuals.

Finding 2: Vitamin E Bioavailability Was Lower in People with Metabolic Syndrome

Estimated vitamin E bioavailability was significantly lower in participants with metabolic syndrome, compared to healthy individuals.

Estimated-Vitamin-E-Absorption

Also, average and maximum levels of vitamin E in blood and lipoproteins were lower over the whole measurement period.

Why the bioavailability of vitamin E was lower in people with metabolic syndrome is unclear.

However, lower levels of vitamin E were associated with higher levels of oxidized LDL and inflammatory markers, suggesting that inflammation or oxidative stress might be involved.

The authors also speculated that metabolic syndrome might be associated with disrupted vitamin E metabolism in the liver or that vitamin E might be temporarily trapped in enterocytes, which are the cells lining the small intestine.

However, further studies are needed before any hard conclusions can be reached.

Bottom Line: The bioavailability of vitamin E was lower in people with metabolic syndrome, compared to healthy individuals.

Finding 3: Dairy Fat Did Not Affect the Absorption of Low-Dose Vitamin E

Dairy fat had no significant effects on vitamin E absorption, regardless of the participants’ health status.

The average vitamin E levels over each 72-hour study visit, presented as area under the curve (AUC), are shown in the chart below. These values represent both vitamin E bioavailability and depletion.

AUC-Metabolic-Syndrome-Vs-Healthy

The results are inconsistent with two previous studies. One of them showed that vitamin E was better absorbed when taken with milk containing 1% fat, compared to orange juice (7).

Another study found that vitamin E absorption was greater when it was taken with whole milk, compared to low-fat milk (8).

However, these studies used very high amounts of vitamin E, or 150–200 mg. In comparison, the participants in the present study supplemented with 15 mg of vitamin E, which is equal to the Recommended Daily Allowance.

In the present study, the researchers also simulated milk digestion in a test tube. Their findings supported the human results – the fat content of milk did not affect the absorbability of 15 mg of vitamin E.

Yet, when the dose was increased to 268 mg, higher amounts of dairy fat significantly increased the potential absorbability of vitamin E.

Bottom Line: Dairy fat did not affect the absorption of vitamin E at low doses (15 mg). However, a test-tube experiment revealed that it may affect the potential absorbability of higher doses (268 mg) of vitamin E.

Limitations

The study didn’t appear to have many limitations, and the study design was excellent.

However, it didn’t allow the researchers to determine the absolute bioavailability of vitamin E. As a result, it may have been underestimated (9).

Summary and Real-Life Application

In short, this study showed that vitamin E bioavailability was lower in adults with metabolic syndrome, suggesting that a higher dietary intake of vitamin E might benefit them.

This is potentially explained by elevated inflammation and oxidative stress in these individuals.

Additionally, although fat is thought to increase vitamin E absorption, the bioavailability of low-dose vitamin E supplements (15 mg) seems to be unaffected.

Tip: Higher fiber intake can play a part in lowering blood glucose levels that are key to fighting metabolic syndrome. Acacia Rigidula and White Kidney Bean Extract are 2 excellent choices to investigate.

Does Night-Time Light Make People Fat?

A large number of things contribute to weight gain.

Too many carbs, not enough protein or fiber, poor gut microbiota, not enough exercise – the list is very long indeed.

Some scientists even believe that night-time light, as insignificant as it may seem, could contribute to obesity over time.

Recently, an observational study examined the association of artificial, night-time light with obesity rates.

Today’s review provides a detailed summary of its findings, and how this insight may help with weight loss.

Background

Living in an urban area is associated with many risk factors for weight gain and obesity. One of them is artificial light-at-night (ALAN).

ALAN comes from a variety of sources, including highways, railways, street lights, buildings, industries and billboards.

The reason why ALAN may contribute to obesity is not entirely clear, but scientists believe that a disrupted body clock and reduced formation of night-time melatonin are involved (12).

Previous studies also show that ALAN exposure may increase weight in laboratory animals (3456).

This is supported by two observational studies suggesting that increased light intensity in people’s bedrooms at night time may increase the risk of weight gain and obesity (78).

However, until now, no studies have examined the association of ALAN with obesity rates on a population level.

Article Reviewed

This study examined the association of artificial, night-time light intensity with obesity rates.

Does artificial light-at-night exposure contribute to the worldwide obesity pandemic?

Study Design

This observational study examined the association of obesity rates with artificial, outdoor, night-time light pollution.

Night-time illumination in residential areas was assessed using recent satellite images from more than 80 countries.

Information on obesity rates was obtained from the World Health Organization (WHO) country-wide database.

When calculating the associations, the researchers statistically adjusted for potential bias by taking the following into account: population wealth (per capita GDP), level of urbanization, birth rate, food consumption and regional differences.

Bottom Line: This observational study examined the association of obesity rates with illumination at night.

Finding: Artificial, Night-Time Light Was Linked With Higher Obesity Rates

On a regional level, greater artificial, night-time light intensity was linked with higher obesity rates in more than 80 countries throughout the world.

Specifically, night-time illumination explained 72–73% of the regional differences in overweight and obesity rates in women and 67–68% in men.

Additionally, the researchers found that when artificial light-at-night levels increased from the minimum amount to the maximum, obesity rates appeared to increase, on average, by about 900% in Asia and 250% in the rest of the world.

Bottom Line: On a regional level, greater light pollution was associated with higher obesity rates.

How Can Night-Time Light Increase Weight Gain?

It is not entirely clear how increased artificial light-at-night might contribute to weight gain and obesity.

However, scientists have come up with several plausible theories:

  • Disrupted sleep quality: Night-time light exposure reduces sleep quality and may disrupt the body clock, potentially contributing to weight gain (910).
  • Increased appetite: Poor sleep and irregular sleeping patterns may disrupt the 24-hour fluctuations of appetite hormones (11).
  • Reduced calorie expenditure: Conversion of brown fat tissue into white fat tissue may slow down metabolic rate and calorie expenditure (12).

In a previous research review, we discussed the possible ways in which a disrupted body clock may affect weight gain and obesity.

Bottom Line: Being exposed to light while sleeping can reduce sleep quality. This may disrupt the body clock, potentially increasing appetite or reducing calorie expenditure.

Does Night-Time Light Really Make People Obese?

A variety of things contribute to weight gain and obesity.

On its own, it’s unlikely that night-time light exposure causes obesity, but when combined with other obesogenic factors it might increase the risk.

Other factors associated with an urban environment have also been linked with an increased risk of obesity. These include:

  • Traffic noise (131415).
  • Traffic-related air pollution (1617).
  • Increased fast food accessibility (18).

However, since most of the evidence is observational, it is difficult to isolate individual factors.

Although the human evidence is limited, controlled animal studies support the idea that night-time light may affect weight gain (35).

Bottom Line: It is unlikely that artificial light-at-night has a large impact on obesity on its own. However, it might contribute to obesity when combined with other risk factors.

Limitations

The study’s main limitation was its observational design.

Simply put, it couldn’t prove that light exposure at night caused weight gain and obesity. Living in urban areas is associated with many other factors that may promote obesity.

Tip: Healthy diet and exercise, minimizing stress (such as night time lighting), and many other factors can be more helpful for weight loss that just taking fad diet pills.

Additionally, this was a population-level study, examining large populations of people rather than individuals.

Second, certain types of light are worse than others. For example, blue light suppresses melatonin formation more than other types of light. Distinguishing between different types of light could provide more accurate results (19).

Bottom Line: This was an observational study. For this reason, it doesn’t prove that night-time light exposure causes obesity.

Summary and Real-Life Application

In short, this study suggests that increased night-time light pollution in people’s bedrooms may increase the risk of obesity.

Night-time light is thought to disrupt the body clock, causing a hormonal imbalance that may affect appetite and/or calorie expenditure.

Due to its observational design, the study doesn’t provide any proof, but the findings are supported by controlled studies in animals.

Regardless of its possible effects on weight gain, a poor night’s sleep is unhealthy. Making sure your bedroom is dark at night may be something to consider.

Tip:
Users of Nicotinamide Riboside most often report increased energy and better sleep, which often go together. Berberine acts in much the same way to increase AMPK activity, which often leads to increased energy and can help with weight loss.

Do Recommendations Underestimate People’s Protein Requirements?

The methods used to assess people’s nutrient requirements are not perfect, and newer and potentially better techniques may change recommendations over time.

For example, new techniques suggest that official recommendations for protein intake may be too low, especially for older people.

Recently, a team of researchers evaluated the protein requirements for older men using the indicator amino acid oxidation (IAAO) technique.

Today’s review provides a detailed summary of their findings.

Protein Rich Foods

Background

Older adults arguably require greater amounts of protein than younger people.

They have reduced rates of protein synthesis, and higher amounts of dietary protein are required to fully stimulate muscle maintenance and growth (1234).

Yet, the current dietary reference intake (DRI) and WHO recommendations are the same for young and old people.

Currently, they are the following:

  • Estimated average requirement (EAR): 0.66 grams per kilogram (0.3 grams per pound) of body weight per day. The EAR refers to the intake level estimated to fulfill the requirements of half of the healthy individuals in the specified group.
  • Recommended daily allowance (RDA): 0.8 grams per kilogram (0.36 grams per pound) of body weight per day. The RDA refers to the intake level estimated to fulfill the requirements of 97% of healthy individuals.

These recommendations are based on nitrogen balance studies, which have several limitations (56).

However, newer studies in older women have used the IAAO technique, which is newer and possibly more accurate (7).

They suggest that the recommended values may be too low for older people (89).

Additionally, studies in older people with protein intakes equal to the current RDA suggest that they may lead to loss of muscle mass (10).

One working group even proposed that the recommendations for older people should be raised to 1.2–1.5 grams per kilogram (0.55–0.68 grams per pound) of body weight per day (11).

However, the evidence is limited and, until now, no studies have estimated the protein requirements of older men using the IAAO technique.

Article Reviewed

This study assessed the protein requirements of older men using the IAAO technique.

Dietary Protein Requirement of Men >65 Years Old Determined by the Indicator Amino Acid Oxidation Technique Is Higher than the Current Estimated Average Requirement.

Study Design

The purpose of this randomized, crossover trial was to assess the dietary protein requirements of six men, aged 65 or older, using the IAAO technique.

Additionally, the researchers compared the values obtained in the present study with those of older women and young men, as previously determined using the same technique (812).

The participants received a total of seven different amounts of protein in a random order in different study periods, separated by one or two weeks.

The amounts of protein tested ranged from 0.2–2.0 grams for each kilogram (0.1–0.9 grams per pound) of body weight per day.

Each level of protein intake was tested over a 3-day period, starting with two adaptation days. On day three, protein requirements were assessed using the IAAO technique (13).

On the adaptation days, the participants received a weight-maintenance diet based on a lactose-free milkshake that provided 1 gram of protein per kilogram (0.45 grams per pound) of body weight per day.

On the third day, the participants arrived at the research center after a 12-hour fast. They then consumed eight hourly meals, each of which represented 1/12th of their daily calorie requirements.

The test day diet consisted of a protein-free liquid formula, Applesauce, grape seed oil and an amino acid mixture resembling the composition of egg protein.

Depending on the amount of protein being tested, the test meal provided 40% of calories from fat, 37–57% from carbs and 3–37% from protein. The diet provided 1.5 times the calories required for weight loss at rest.

Bottom Line: The purpose of this study was to assess the protein requirements of older men using the IAAO technique and compare the findings with previous studies using the same technique.

Finding 1: Protein Requirements of Older Men Are Higher Than Recommendations

The study showed that both the EAR and RDA for protein were higher than official recommendations.

  • EAR: 0.94 grams per kilogram (0.43 grams per pound) of body weight per day.
  • RDA: 1.24 grams per kilogram (0.56 grams per pound) of body weight per day.

These values are similar to what the same research team has found in older women using the same method (812).

The chart below compares the current findings with the official recommendations:

EAR and RDA Protein

Simply put, the current EAR and RDA for older people may be underestimated by 30%.

However, before any strong conclusions can be reached, larger studies need to confirm the findings.

Bottom Line: This study suggests that the current recommended protein intake for older people may be underestimated by around 30%.

Finding 2: Protein Requirements May Increase with Age

The researchers compared the findings of the current study with previous studies in young men and older women using the same technique (812).

The chart below shows the comparison of the EAR for protein between groups. Protein requirements are either expressed for each kilogram of body weight per day (BW) or for each kilogram of lean body mass per day (LBM).

Protein In Populations

The protein requirements for each kilogram of body weight were equal between all three groups. However, on the basis of lean body mass, they were higher in older men and women, compared to young men.

Bottom Line: Based on lean body mass, the protein requirements of older people were higher, compared to young people.

What Are the Health Effects of Inadequate Protein Intake?

Eating inadequate amounts of protein has adverse health effects, especially in older people.

These include the following:

  • Muscle loss (sarcopenia) (1415).
  • Decreased muscle strength and function (1617).
  • Bone loss and an increased risk of fractures (18192021).
  • Reduced immune response, increasing the risk of infections (22).

Accordingly, one observational study showed that higher protein intakes were associated with fewer health problems in older people (23).

Bottom Line: Inadequate protein intake may promote muscle and bone loss and reduced strength. Additionally, it may impair the body’s immune response to infections.

Limitations

This study had an excellent design, but one of its main limitations was the low number of participants.

Also, since the study used a marker of protein requirements, the true relevance of the findings need to be tested in long-term trials. However, conducting such trials may be difficult.

Finally, the body may be able to adjust to low protein intakes, but this study did not take such adaptations into account (24).

Summary and Real-Life Application

This study suggests that the current recommendations for protein intake among older men is underestimated by around 30%.

However, before the recommendations can be changed, the findings need to be validated by further studies.

Tip:
Acacia Rigidula or Glucomannan are great additions to your diet to improve gut microbiota. Probiotics can influence weight loss in a much healthier manner than Garcinia Cambogia extract.

Changes in Gut Bacteria Are Linked to Diet and Disease

The human digestive system is home to trillions of bacteria and other microbes (1).

Collectively known as the gut microbiota or gut flora, this is one of the most active areas of research in nutrition, obesity and human physiology.

Recently, a review article discussing the role of the microbiota in the development of obesity and metabolic diseases was published in Advances in Nutrition.

Below is a summary of the review’s main points.

Stomach Middle Section of Overweight Man

Article Reviewed

Scientists at the University of Copenhagen, Denmark, reviewed the available evidence linking the gut microbiota with obesity, metabolic diseases and diet.

Can We Prevent Obesity-Related Metabolic Diseases by Dietary Modulation of the Gut Microbiota?

Beneficial Functions of the Gut Microbiota

Most of the gut microbiota lives in the colon, which may host more than 1,000 different species of bacteria (23).

Some of these bacteria have beneficial or even essential functions, whereas others are neutral or potentially harmful.

In healthy people, beneficial bacteria dominate the gut environment. Their most important functions are to:

  • Produce short-chain fatty acids to feed the cells that line the colon (4).
  • Protect the gut wall and keep harmful substances out of the blood (567).
  • Reduce the growth of harmful microbes by competing with them for resources.
  • Form essential vitamins, such as vitamin K (8).
  • Regulate the immune system (9).

Bottom Line: Our digestive system is home to trillions of bacteria, many of which have beneficial or even essential functions.

Imbalanced Gut Microbiota is Linked to Disease

A well-balanced gut microbiota is a sign of good health.

Unhealthy lifestyle habits and certain diseases are associated with a microbiota that is imbalanced or at least different from that of healthy people. This condition is sometimes called dysbiosis.

Adverse conditions that have been associated with changes in the gut microbiota include inflammatory bowel disease, type 2 diabetes, atherosclerosis and non-alcoholic fatty liver disease (310111213).

The gut microbiota of obese people is also different from that of normal-weight people (1415).

However, these are all observational studies that can’t demonstrate that improved gut microbiota leads to fast weight loss, and the true explanation for these associations is currently unknown.

Yet experiments in mice and humans suggest that the microbiota may play at least some role in the development of obesity and metabolic syndrome (161718).

This is an active area of research, and new pieces to the puzzle are gradually being discovered.

Bottom Line: Several adverse conditions, such as metabolic disorders and obesity, are associated with an imbalanced microbiota.

How Do Nutrients Affect the Gut Microbiota?

Multiple factors affect the gut microbiota, including genetics, age and how you’re born. Yet the most important factor is probably your diet — what you eat and how much (19202122232425).

Below is a detailed overview of how different nutrients affect the gut microbiota.

Carbs and Fiber

Carbs are usually the main component of the human diet, and for this reason, the most common types of gut bacteria feed on carbs (26).

Some carbs, such as resistant starch, pass to the colon undigested. There, they are fermented by beneficial bacteria that produce short-chain fatty acids (SCFAs).

Tips: Applesauce has a lot of beneficial Antioxidants, but is very low in fiber and high in carbs and calories, so is not really as healthy as many people think.

SCFAs are the main sources of nutrition for the cells lining the colon, and essential for colon health.

Additionally, a high rate of carb fermentation helps maintain a slightly acidic environment within the colon, favoring the growth of beneficial bacteria (242728).

However, certain types of fiber are better than others. These are known as prebiotics, and include fiber such as inulinGlucomannan, White Kidney Bean Extract, galacto-oligosaccharidesfructo-oligosaccharidesresistant starch and arabinoxylan (29).

By increasing the activity and growth of beneficial bacteria, prebiotics have a variety of health benefits (30).

Yet keep in mind that easily digested carbs, such as sugar and refined carbs, do not offer the same benefits as whole, fiber-rich carbs.

Bottom Line: Fiber is essential for many beneficial gut bacteria. The healthiest types of fiber are collectively known as prebiotics.

Fat

Animal studies indicate that very high fat consumption may lead to metabolic endotoxemia (3132).

Metabolic endotoxemia is characterized by high circulating levels of lipopolysaccharides, triggering an inflammatory response in the body.

Lipopolysaccharides, also known as endotoxins, are found in the membranes of gram-negative bacteria, which are potentially harmful.

Scientists have suggested that metabolic endotoxemia may be associated with an imbalanced gut microbiota.

They speculate that endotoxins from harmful bacteria may somehow escape across the gut wall and into the blood stream, promoting metabolic disorders (333435).

This idea is supported by observational studies that have associated high levels of lipopolysaccharides with obesity, type 2 diabetes and metabolic syndrome (3637383940).

Interestingly, eating prebiotic fiber may counteract many of these effects (4142).

However, more human studies are needed before any strong conclusions can be reached.

Bottom Line: Animal studies have associated high fat intake with metabolic endotoxemia. However, prebiotics may counteract these effects

Protein

Little is known about the effects of protein on the gut microbiota, but several studies indicate that a high intake of protein may be harmful for colon health.

Undigested protein may reach the colon, where it is fermented by bacteria that produce potentially harmful substances (274344).

This may not be a concern on a well-balanced diet, since eating prebiotic fiber may counteract some of these effects (45).

Bottom Line: High protein intake may have adverse effects on colon health, but prebiotics may counteract some of them.

Probiotics

Probiotics are live bacteria that provide health benefits when consumed (46).

These include friendly bacteria such as Bifidobacteria and Lactobacillus Gasseri, which have numerous health benefits including weight loss (47).

Supplements that contain both probiotics and prebiotics are known as synbiotics.

Synbiotics help the friendly bacteria survive and grow in the digestive tract, and are probably more effective than taking probiotics or prebiotics separately (48).

Bottom Line: Numerous studies show that probiotics may have various health benefits. These benefits may be greater when probiotics are taken with prebiotics.

Treating Metabolic Conditions Through Diet

A few human trials have found that supplementing with dietary fiber, including prebiotics, may change the gut microbiota. It may also improve insulin sensitivity, systemic inflammation and lipid metabolism (49505152).

Although these findings clearly show that taking prebiotics may improve metabolic disorders, they do not prove that these disorders were caused by an imbalance in the gut microbiota.

In fact, supplementing with prebiotics might improve metabolic conditions independently from their effects on the microbiota (53).

Bottom Line: Human trials have shown that prebiotics may improve metabolic disorders and change the gut microbiota. However, the role of the microbiota is still unclear.

Summary and Real-Life Application

In short, this review shows that metabolic disorders, such as obesity, are associated with changes in the gut microbiota.

Additionally, studies indicate that improving the gut microbiota may help treat metabolic disorders. However, the causal role of the microbiota has yet to be proved.

Certain types of fiber, known as prebiotics, are probably the most effective dietary strategies for maintaining a healthy gut microbiota.

Tips: A healthy gut microbiota can be more beneficial in keeping weight off than fad pills like Garcinia Cambogia or Alli.

Fast Weight Loss Does Not Promote Weight Regain

To successfully lose weight and keep it off, you usually need to change your lifestyle.

Short-term dieting or pills like Garcinia Cambogia don’t work in the long-term, since most people just gradually gain the weight back again. What’s more, some people have suggested that fast weight loss may cause even greater weight regain.

For this reason, researchers from the Netherlands compared weight regain after rapid and slow weight loss. Their findings were recently published in Obesity.

Background

Weight regain after dieting is a well-known problem. Two human trials showed that one year after dieting, only 20% of the subjects had avoided weight regain (12).

Another study found that two years after dieting the participants had, on average, regained approximately 70% of the weight they lost (3).

A widely held belief is that fast weight loss causes people to regain more body fat later on, but this has not been scientifically proved (45).

The idea seems scientifically plausible, due to low protein intake and a loss of muscle mass, which are explained below:

  • Low protein intake: Fast weight loss comes from following very low-calorie diets. These diets contain lower amounts of protein.
  • Loss of muscle mass: Eating very little protein increases muscle mass loss, reducing calories burned and making it harder to keep weight off (67).

However, previous studies have found no evidence that fast weight loss leads to more weight regain, when compared to more gradual weight loss (38).

Article Reviewed

This article describes the findings of a randomized trial comparing the effects of fast and slow weight loss on weight regain after dieting.

The Effect of Rate of Weight Loss on Long-Term Weight Regain in Adults with Overweight and Obesity.

Study Design

The purpose of this randomized trial was to examine whether losing weight fast has any effects on weight regain after dieting stops.

A total of 61 overweight or obese men and women started the study. They were randomly assigned to one of two groups:

  • Slow weight loss: A 12-week, low-calorie diet, aiming for 10% weight loss. Each day, it provided 1,250 kcal, 90 g protein, 150 g carbs and 32 g fat.
  • Fast weight loss: A 5-week, very-low calorie diet, aiming for 10% weight loss. Each day, it provided 500 kcal, 52 g protein, 52 g carbs and 8 g fat.

After the calorie-reduced diet, the participants went on a 4-week weight maintenance diet. Their weight regain was then monitored for 9 months after they stopped dieting.

The second group consumed very low carbs. Neither group used any weight loss pills or probiotics for weight loss.

At the start and end of each of the study periods, the researchers measured body weight and composition.

Bottom Line: This was a randomized trial examining how the rate of weight loss affects weight regain after dieting.

Finding 1: Rate of Weight Loss Did Not Affect Regain

In both groups, the participants lost similar amounts of body weight, ranging from 18–20 lbs (8–9 kg), on average.

During the 9-month follow-up period, 75% of the participants gained back more than 50% of their lost weight.

This weight regain was similar in both groups, as shown in the chart below.

These results are supported by previous studies showing that fast and slow weight loss resulted in similar weight regain (38).

Bottom Line: The study showed that the rate of weight loss does not affect weight regain after dieting stops.

Finding 2: Fast Weight Loss Reduced Lean Mass

One of the downsides of dieting is the loss of lean mass, which is a measure of the body’s fat-free mass — muscles, bones and water.

The amount of muscle mass you have is a strong determinant of how many calories your body burns (67).

In the present study, losing weight fast led to more lean mass loss.

Tips: Adding more fiber to your diet, such as Glucomannan or White Kidney Bean Extract can lead to more gradual weight loss without losing muscle mass

The chart below shows the differences between groups, presenting lean mass loss as a percent of total weight loss.

Losing weight fast caused a 1.3 lbs (0.6 kg) greater loss of lean mass, compared to a more moderate weight loss approach.

Additionally, loss of lean mass was associated with greater weight regain in both groups. However, this was not enough to cause a significant difference in weight regain between groups.

Bottom Line: Fast weight loss led to a greater lean mass loss, which was significantly associated with weight regain in both groups. However, this was not enough to cause differences in weight regain between groups.

Limitations

This study was both well designed and implemented, and did not seem to have any serious limitations.

Its main weakness was the method used to assess lean mass, as it did not allow the researchers to distinguish between body water and muscle mass.

It also did not examine differences in lower blood sugar or increased energy.

Summary and Real-Life Application

In short, this study showed that losing weight fast did not affect weight regain after dieting stopped.

However, fast weight loss had one downside. It caused a greater reduction in lean mass, compared to slower weight loss.

Tips: Add some Cumin to your meals can lead to less calorie consumption and gradual weight loss.

Even though fast weight loss does not affect weight regain, a more gradual weight loss approach is probably a better option, since it may help you retain muscle mass.

Eating Dairy May Reduce Heart Disease Risk

Many studies indicate that dairy products may protect against heart disease (1).

To expand and update the evidence base, a team of researchers conducted a meta-analysis, combining the results of 31 previous observational studies.

Below is a detailed overview of their results, recently published in the British Journal of Nutrition.

Knife Cutting Cheeses

Background

Many studies suggest that dairy products may protect against protect against heart disease . Yet most of the available evidence is based on observational studies, which can’t prove causation (1).

On the other hand, some scientists have suggested that high-fat dairy containing saturated fat may increase the risk of heart disease by raising LDL-cholesterol (23).

This is controversial, since dairy products have also been shown to raise HDL-cholesterol and reduce blood pressure (3456).

What’s more, emerging evidence indicates that saturated fat does not increase heart disease risk — its effect may simply be neutral (78910).

Other studies suggest that milk fat may have different effects on risk factors for heart disease, since different dairy product have Probiotics, depending on what dairy product it comes from (11).

Article Reviewed

A group of researchers from EpidStat Institute, USA, did a systematic review and meta-analysis of observational studies examining the association of dairy products and heart disease.

Dairy consumption and CVD: a systematic review and meta-analysis.

Study Design

This was a systematic review and meta-analysis of observational studies examining the association between dairy products and heart disease.

A total of 31 prospective cohort studies, including over one million adults, were selected using strict inclusion criteria.

A prospective cohort study is a type of observational study that follows individuals over time, investigating how certain factors affect the rates of a certain outcome.

In the present meta-analysis, the included studies assessed dairy consumption using food frequency questionnaires. They then followed the participants for 5–26 years, while recording all heart disease events.

Outcome values included:

  • Heart disease: Diseases of the heart and blood vessels are collectively known as heart disease, or cardiovascular disease. This includes conditions such as heart attacks, coronary heart disease, heart failure and stroke.
  • Coronary heart disease (CHD): This disease is characterized by the clogging of the blood vessels that supply the heart with oxygen. It may eventually lead to heart attacks or heart failure.
  • Stroke: Also known as brain attack, stroke is when blood flow in the brain is interrupted, leading to cell death. This may be caused by clogged or ruptured blood vessels.

Total carb intake was not measured, nor weight loss.  In addition to examining the association of total dairy intake with heart disease, the researchers divided dairy products into categories and did sub-analyses on each of the groups.

These categories included milk, cheese, yogurt, calcium from dairy products, low-fat dairy and full-fat dairy.

Bottom Line: This was a systematic review and meta-analysis examining the association of dairy consumption with heart disease, coronary heart disease and stroke.

Finding 1: Eating Dairy Reduced the Risk of Heart Disease

This study suggests that total dairy intake is associated with a reduced risk of heart disease, coronary heart disease and stroke.

In fact, the reduction in risk may be as high as 5–15%, regardless of fat content.

Additionally, there were no significant differences between intake levels. One serving per day appeared to be as beneficial as three servings.

These results are also supported by previous meta-analyses on the association of dairy products with heart disease, coronary heart disease and stroke (1).

Bottom Line: Total dairy consumption was associated with a reduced risk of heart disease, coronary heart disease and stroke.

Finding 2: Eating Cheese Reduced the Risk of Heart Disease

Previous studies indicate that eating fermented dairy products, such as cheese, may protect against heart disease (12).

The present study supports earlier findings, suggesting that cheese may reduce the risk of coronary heart disease by 18% and stroke by 13%.

All levels of intake appeared to be protective.

Bottom Line: Eating cheese was significantly associated with a reduced risk of coronary heart disease and stroke.

Additional Findings

Several additional findings were reported, including:

  • No benefits from milk: Drinking milk was not associated with a reduced risk of heart disease, coronary heart disease or stroke.
  • Calcium reduced stroke risk: Calcium from dairy products was not significantly linked with coronary heart disease. However, it was associated with an estimated 31% reduction in the risk of stroke, on average.
  • Yogurt is inconclusive: Due to lack of data, the study couldn’t form any conclusions about the effects of consuming yogurt. More studies are needed.

Bottom Line: Milk consumption was not associated with a reduced risk of heart disease, whereas dairy calcium seemed to protect against coronary heart disease. The effects of eating yogurt are still unclear.

Limitations

This systematic review and meta-analysis appears to have been well planned and implemented. Nevertheless, it has one important limitation: it used data from observational studies, which can’t prove causation.

For example, people who eat a lot dairy products may simply have healthier lifestyle habits, compared to those who eat less dairy.

Tip:  Other diet factors such as total fiber consumed were also not measured.  It is well know that Glucomannan and Acacia  Rigidula can have a big impact at lowering heart disease risk.

However, most of the studies included in this meta-analysis adjusted for dietary and lifestyle factors, and other studies have consistently reported similar associations.

This indicates that the observed associations are at least partly due to the direct effects of dairy consumption on heart disease risk.

Finally, it would have been interesting if the study had looked into the effects of different dairy fats. For example, butter appears to raise LDL-cholesterol to a greater extent than cream, as discussed in our previous research review (11).

Bottom Line: This study was both well planned and implemented. However, it was based on observational studies, which can’t prove a cause-and-effect relationship.

Summary and Real-Life Application

This study suggests that consuming dairy products may reduce the risk of heart disease, coronary heart disease and stroke.

Among the different types of dairy products, cheese seems to be an especially good choice.

Simply put, eating dairy appears to be healthy for your heart and blood vessels.

Tip: Milk contains Nicotinamide Riboside, which has many anti-aging properties in addition to heart health.

Pulses May Cause Modest Weight Loss

To lose weight fast, the importance of real food should not be disregarded.

Pulses, the seeds of legumes, may be one of those foods that help you lose weight.

Recently, a team of researchers reviewed and analyzed the available data. Here is a detailed summary of their findings.

Twelve Spoons with Pulses or Legumes

Background

The seeds of legumes are collectively known as pulses. However, not everyone agrees on what pulses are.

According to the United Nations’ Food and Agricultural Organization (FAO), the name pulse only refers to legumes that are harvested for their dry seeds. This definition excludes green beans, green peas, soybeans and peanuts.

Several controlled trials suggest that eating pulses may have benefits for those trying to lose weight. However, their findings are not entirely conclusive (1234).

Factors such as the amount eaten, trial duration, number of participants (statistical power) and the type of pulse examined result in inconclusive findings.

For this reason, combining the results of similar studies in a meta-analysis may increase statistical power, providing more accurate estimates of the truth.

Only one previous meta-analysis examined the effect of pulses on body weight. This meta-analysis, which was published in 2002 and included 8 randomized controlled trials, concluded that pulses do not reduce body weight (5).

However, many new studies have been published since then, justifying an update.

Diet Tips:
Product like garcinia cambogia appeal to a quick fix mentality, but recent studies are pointing to many foods that can help achieve weight loss without resorting to alli or other pills.

Cumin is a spice you can add to just about any food that can help.

probiotic can also aid in weight loss

Adding acacia rigidula or white kidney bean to any food can slow absorption and lower the glycemic index.

Article Reviewed

This was a review and analysis of studies examining how pulses affect body weight.

Effects of dietary pulse consumption on body weight: a systematic review and meta-analysis of randomized controlled trials.

Study Design

This was a systematic review and meta-analysis of randomized controlled trials on the effect of pulses on body weight, body fat or weight circumference.

In this study, pulses were defined as all leguminous seeds, except for oilseeds — soybeans and peanuts. These included beans, lentils, chickpeas, dry peas and lupin.

The analysis included 21 trials, including a total of 940 participants. All of the trials had the following characteristics:

  • They were randomized controlled trials, comparing a diet rich in pulses with a diet that didn’t contain any pulses.
  • The trials examined the effects of whole pulses on body weight, waist circumference or body fat percentage.
  • The diets contained the same amount of calories.
  • They were three or more weeks in duration.

Bottom Line: This was a systematic review and meta-analysis of randomized controlled trials examining the effects of pulses on body weight.

Finding 1: Pulses Reduced Body Weight

This meta-analysis showed that eating pulses may promote modest weight loss in overweight or obese middle-aged men and women.

On average, eating 132 grams of cooked pulses per day (or one serving) led to 0.75 lbs (0.34 kg) greater weight loss over a period of 6 weeks, compared to a diet that didn’t contain any pulses.

Pulses had weight loss benefits even when the diets were not intentionally calorie restricted. This suggests that eating pulses may be an effective alternative to calorie-reduced diets, which may be difficult to stick to in the long-term.

The findings are not supported by a previous meta-analysis, published in 2002 (5).

However, that analysis only included 8 trials, and may not have had enough statistical power to detect differences as significant.

Bottom Line: The analysis showed that eating pulses may cause modest weight loss, even when diets are not calorie-reduced.

Finding 2: Pulses Did Not Reduce Waist Circumference

Six of the included trials, which had a total of 509 participants, examined the effects of eating pulses on waist circumference.

Overall, eating pulses did not significantly reduce waist circumference.

However, when one study was removed from the analysis (6), waist circumference decreased by a significant 1%.

Body fat tended to decrease, but the difference between groups was on the verge of being statistically significant.

Bottom Line: Eating pulses did not significantly reduce waist circumference or body fat.

Why Do Pulses Have Weight Loss Benefits?

The main reason why pulses promote weight loss is probably their ability to increase fullness and reduce appetite (78910).

They have several nutritional properties that make them especially satiating or filling. These include:

  • Soluble fiber: Pulses are rich in soluble fiber, which may slow stomach emptying, contributing to fullness (11).
  • Resistant starch: Some of the starch in beans is resistant to digestion. This slightly reduces energy content, benefits gut microbiota and helps with fullness.
  • Protein: Pulses are high in protein, which also promotes fullness (12).
  • Glycemic index: Pulses are low on the glycemic index, improving blood sugar levels. This may potentially prevent overeating (1314).

Additionally, pulses are affordable and may have a number of other health benefits, potentially reducing the risk of heart disease and type 2 diabetes (151617).

Bottom Line: Pulses may promote weight loss by increasing fullness and calorie intake during a meal.

Limitations

This meta-analysis had several potential limitations.

First, the findings of one trial may have been largely responsible for the significant effects detected (4).

Second, many of the included trials were of short duration, or only 4–10 weeks. Further studies need to assess the long-term effects of a diet high in pulses.

Third, only 42% of the included trials were considered to be of high quality, according to the Heyland Methodologic Quality Score.

Finally, this meta-analysis did not distinguish between different types of pulses.

Although all pulses have several beneficial properties in common, it is possible that some of them are more effective than others.

Bottom Line: This meta-analysis had a few limitations. Many of the studies included were of low quality and short duration. Additionally, the analysis did not distinguish between the different types of pulses.

Summary and Real-Life Application

This meta-analysis showed that eating pulses may promote a slight weight loss, even on a diet that’s not calorie-reduced.

The ability of pulses to promote fullness and reduce appetite during a meal may be responsible for these effects.

Simply put, if you are trying to lose weight, adding one serving or a cup of cooked beans, lentils, peas or chickpeas do your daily diet could make a difference.

Diet Tips:
Beside proper nutrition, there are products like niagen by elysium health that increase energy so can burn more fat.
Also, berberine increases AMPk activity which is key to cellular energy levels.

Eating Salty, High-Fat Food May Promote Weight Gain

Regular overeating leads to weight gain, especially when high-fat food is involved.

On its own, fat tastes rather bland and people are unlikely to binge on it. However, mixing it with savory flavors, sugar or salt can make it very tasty.

Recently, a team of scientists examined how fat and salt affect calorie and food intake. Below is a detailed summary of their results.

Macaroni and Tomato

Background

Most people know that eating too much fat promotes weight gain and obesity (12).

This is because, gram for gram, fat is very rich in calories. Additionally, its appetite-suppressing effects are relatively weak (3456).

What’s more, fat is often mixed with salt, which makes it tastier — making people more likely to overeat and become obese (7891011).

Article Reviewed

A team of Australian researchers examined the effects of fat and salt on food intake.

Salt Promotes Passive Overconsumption of Dietary Fat in Humans.

Study Design

This randomized, crossover trial examined the effects of fat and salt on food intake.

It also investigated how fat taste sensitivity affects appetite after meals, and whether this was influenced by salt intake.

48 healthy men and women participated in the four test days of the study.

Each day, all participants had a standardized breakfast consisting of plain mini-croissants, after which they were assigned to four lunch meals in a random order.

These lunch meals all consisted of 56% cooked elbow macaroni with 44% Coles home-brand sauce (based on tomato passata) and a jug of water.

The total amount of macaroni and sauce was 1,350 grams and the participants were allowed eat as much as they wanted, or until they were comfortably full.

Depending on the lunch meal, the sauce provided different amounts of fat and salt, as shown below:

  • Low-fat, low-salt: 0.02% fat and 0.06% salt — 100% tomato passata.
  • Low-fat, high-salt: 0.02% fat and 0.5% salt — 100% tomato passata with added salt.
  • High-fat, low-salt: 34% fat and 0.06% salt — 60% tomato passata with added canola oil (30%) and thickened cream sauce (10%).
  • High-fat, high-salt: 34% fat and 0.5% salt — 60% tomato passata with added salt, canola oil (30%) and thickened cream sauce (10%).

All four meals contained approximately the same amount of protein and carbs.

The low-salt sauces contained no added salt. The high-salt sauce had optimally pleasant saltiness, based on the results of previous studies (91112).

Since the trial had a crossover design, the participants consumed all of the above lunch meals on different occasions, separated by one week.

Before and after each lunch meal, the researchers measured food intake, calorie intake and subjective ratings of appetite.

On two occasions, fat taste sensitivity was also estimated by determining the minimum amount of oleic acid — a common unsaturated fat — the participants were able to taste.

Bottom Line: This was a randomized, crossover trial examining the effects of salt and fat on food and calorie intake.

Finding 1: Salt Increased Food and Calorie Intake

Salt increased both food and calorie intake by 11%, regardless of the amount of fat in the meals. These findings are shown in the chart below:

Effects of Salt on Food Intake Both

The study also found that salty meals were rated more pleasant than non-salty meals, likely explaining why saltiness caused people to eat more.

Bottom Line: Saltiness increased food and calorie intake by 11%, regardless of the amount of fat. This was probably because salting made the food taste better.

Finding 2: Fat Taste Sensitivity Reduced Fat Intake

Those participants who were sensitive to the taste of fat tended to eat less of it, which would help to lose weight.

However, the study showed that fat intake was only reduced when the lunch meal contained low amounts of salt.

These findings suggest that people who are sensitive to the taste of fat are less likely to overeat on a high-fat diet, but that high amounts of salt may override this reduction in appetite. This is supported by previous studies (11131415).

Bottom Line: High fat taste sensitivity was associated with a lower consumption of fat. However, salt seemed to override this reduction.

Finding 3: Fat Affected Food Intake in Women

Overall, fat had no significant effects on the amount of food eaten during the meals.

In other words, despite the high calorie content of fat, the participants did not compensate by eating less of it. Alli can help block fat absorption.

In fact, calorie intake was 60% higher during the high-fat meals.

However, women appeared to be slightly less greedy than men when it came to fat. They ate 15% less of the high-fat meals by weight, compared to the low-fat meals.

Bottom Line: Women ate 15% less of the high-fat meals, compared to the low-fat meals.

Limitations

This study had several limitations.

First, it assessed the effects of only one type of food.

Second, the amount of fat in the high-fat meal was greater than what people normally eat during one meal. However, by using very high-fat meals, the study clearly showed that fat doesn’t have much effect on appetite.

Finally, the study only measured one meal. Further studies need to examine if a high-salt diet has any effects on weight gain and obesity in the long term.

Summary and Real-Life Application

The study showed that salt increased food and calorie intake, regardless of its fat content. This is probably because salt makes food more pleasant or tasty to eat.

Simply put, eating a lot of salty food may promote overeating and weight gain, especially if the food is also high in fat.

Diet Tips: Cumin can help with weight loss by increasing satiety. Glucomannan and acacia rigidula are soluble fibers that slow down food absorption to reduce glycemic index, especially when added to high calorie foods like applesauce. Making smart food choices is more effective than taking garcinia cambogia for weight loss.

Low-Fiber Diets Harm the Good Bacteria in Your Gut

A lack of fiber is one of the main flaws of the modern diet.

Whole plant foods have largely given way to heavily processed products that have lost most of their fiber.

Growing evidence suggests that low-fiber diets may adversely affect the gut microbiota, contributing to the development of many chronic lifestyle diseases.

A recent review discussed the importance of dietary fiber for the beneficial bacteria living in your gut, and how you can preserve a healthy gut microbiota.

Article Reviewed

This review discussed the importance of maintaining a healthy gut microbiota by eating enough fiber and probiotic for weight loss.

The Fiber Gap and the Disappearing Gut Microbiome: Implications for Human Nutrition.

What is the Gut Microbiota?

The microbes — bacteria and yeasts — living in your digestive system are collectively known as the gut microbiota or gut flora.

Most of these microbes rely on the things you eat. For example, some thrive on fiber, whereas others multiply when your diet is high in fat and sugar.

Simply put, your dietary choices determine what types of bacteria live in your digestive system. This can have important health implications and weight loss efforts
.

Generally, a diet based on whole, fiber-rich foods promotes the growth of beneficial bacteria, whereas other diets may favor bacteria you would do better without.

Bottom Line: The bacteria in your digestive system are collectively known as the gut microbiota. Their numbers and diversity depend on your diet.

The Importance of a Healthy Gut Microbiota

A healthy gut contains trillions of bacteria. The types of bacteria that are dominant, as well as their quantities, are also important.

For optimal health, your gut should host a variety of beneficial bacteria. Some of their health benefits include:

  • Colon nutrition: The bacteria produce short-chain fatty acids in your colon, providing nutrition for the cells lining the colon, improving colon health and reducing inflammation (1).
  • Stronger gut wall: The bacteria may protect and strengthen the gut wall, preventing harmful substances from entering the blood (234).
  • Vitamin K: The bacteria also produce vitamins, such as vitamin K (5).
  • Immune system regulation: Animal studies indicate that the gut microbiota provides the immune system with important signals, regulating its function (6).

An imbalance in the gut microbiota, often referred to as dysbiosis, is when beneficial bacteria are lacking and undesirable bacteria overpopulate the gut.

As discussed in a previous research review, dysbiosis is associated with inflammation, obesity and metabolic diseases.

Bottom Line: Your health may depend on the dominant bacteria in your gut. Some may harm your body, whereas others provide health benefits.

Is the Gut Microbiota Disappearing?

Evidence indicates the modern diet may have led to the loss of beneficial microbes.

The consumption of processed foods has increased, and diets may have become deficient in fiber, at least compared to pre-industrial levels (7).

This is supported by observational studies comparing the gut microbiota of people living in primitive societies with that of people living in Western countries.

For example, gut microbial diversity is significantly greater in people living in rural communities in Papua New Guinea, South America and Africa, compared to people in the US and Europe (8).

Furthermore, the average diet of people in Western society is low in fiber. In fact, it’s only half of what is recommended in official guidelines (9).

Bottom Line: The Western diet contains low amounts of fiber. This may have led to a reduction in the diversity of microbes living in people’s guts.

A Low-Fiber Diet Harms the Gut Microbiota

Multiple factors may affect the gut microbiota. However, the strongest determinant of gut microbial health and diversity is your diet, especially your fiber intake.

Not all fiber is equal. The types of fiber that promote the growth of beneficial bacteria are known as prebiotics or microbiota-accessible carbohydrates (MACs) (10).

Prebiotics are indigestible carbs that pass down into the lower parts of the digestive tract, where they are fermented by the resident bacteria.

A diet deficient in prebiotic fiber reduces the numbers of bacteria that rely on them. Foods like applesauce might seem healthy but are have no fiber.

As a result, levels of short-chain fatty acids in the colon decrease, potentially leading to poor colon health and inflammation (11).

Bottom Line: Fiber intake is very important to gut microbial health. A prolonged low-fiber diet may reduce the numbers of beneficial bacteria.

How to Preserve the Gut Microbiota

The single most important thing you can do to preserve your gut microbiota is to eat enough prebiotic fiber.

Human studies have shown that eating fiber and whole grains increases the diversity of fecal bacteria, which is an indicator of bacterial diversity in the colon (1213).

Although fiber can be obtained from a variety of whole foods, supplements may be convenient for those who find it hard to get enough from their diet.

Here is a list of a few types of prebiotic fiber:

  • Beta-glucan: Found in cereals, especially oats and barley (14).
  • Galacto-oligosaccharides: A food additive also sold as a supplement (15).
  • Guar gum: A food additive widely used in a variety of products (16).
  • Inulin: Found in chicory root, Jerusalem artichokes, garlic, onions and asparagus (17).
  • Pectin: Found in fruits, such as apples, oranges, plums and bananas (18).
  • Resistant starch: Found in whole grains, legumes, green bananas and potatoes (19).

Bottom Line: Eating enough prebiotic fiber may be a good way to preserve or even restore the gut microbiota.

Summary and Real-Life Application

Evidence indicates the modern lifestyle may have reduced the number of beneficial gut bacteria, potentially contributing to chronic disease such as high blood sugar.

The low fiber content of the Western diet is partly to blame.

So if you value your health, getting enough prebiotic fiber from whole foods or supplements should be a high priority for natural weight control without resorting to pills like garcinia cambogia or alli.

Can NMN really reverse Aging? (backup)

As we age, our levels of the Co-enzyme Nicotinamide Adenine Dinucleotide NAD+ drop significantly in multiple organs in mice and humans  (5,8,10).

NAD+ decrease is described as a trigger in age-associated decline(23), and perhaps even the key factor in why we age (5).

In 2013, research published by Dr David Sinclair demonstranted that short term supplementation with Nicotinamide MonoNucleotide (NMN) reversed many aspects of aging, making the cells of old mice resemble those of much younger mice, and greatly improving their health (8).

 

The quotes below are directly from that research:

NMN was able to mitigate most age-associated physiological declines in mice”

“treatment of old mice with NMN reversed all of these biochemical aspects of aging”

Since that landmark 2013 study, dozens of others have been published investigating the efficacy of supplementation with NMN in treatment and prevention of a wide range of disease including cancer, cardiovascular disease, diabetes, Alzheimers, Parkinsons, and more (5,6,7,9,10,11,13,14,15,16).

According to Dr Sinclair:

enhancing NAD+ biosynthesis by using NAD+ intermediates, such as NMN and NR, is expected to ameliorate age-associated physiological decline

WHAT IS NAD+

NR benefits chartNAD+ is a key co-enzyme that the mitochondria in every cell of our bodies depend on to fuel all basic functions. (3,4)

NAD+ play a key role in communicating between our cells nucleus and the Mitochondria that power all activity in our cells (5,6,7)

NAD+ LEVELS DECREASE WITH AGE

NAD+ levels decreaseAs we age, our bodies produce less NAD+ and the communication between the Mitochondria and cell nucleus is impaired. (5,8,10).

Over time,  decreasing NAD+ impairs the cell’s ability to make energy, which leads to aging and disease (8, 5) and perhaps even the key factor in why we age (5).

NAD+ METABOLISM IN HUMANS


NAD+ can be synthesized in humans from several different molecules (precursors), thru 2 distinct pathways:
De Novo Pathway

  • Tryptophan
  • Nicotinic Acid (NA)

Salvage Pathway

  • NAM – Nicotinamide
  • NR – Nicotinamide Riboside
  • NMN – Nicotinamide MonoNucleotide

The NAD+ supply is constantly being consumed and replenished through the Salvage Pathway, with approximately 3g of NAM metabolized to NMN and then to NAD 2-4 times per day (14).

  • The salvage pathway sustains 85% or more of our NAD+ (14)
  • Nampt is the rate-limiting step in the salvage process (97).
  • As we age, Nampt enzyme activity is lower, resulting in less NAM recycling, less NAD+, more disease and aging (97,101).

ALL PRECURSORS BOOST NAD+ SIGNIFICANTLY IN LIVER

NAM, NA, NMN, NR, and Tryptophan ALL elevate levels of NAD+ significantly in the liver, which has many benefits for metabolic health.

This chart from the Trammell thesis shows the impact on liver NAD+ for mice given NR, NAM, and NA by oral gavage 0.25, 1, 2, 4, 6, 8 and 12 hours before testing.

Charts showing NMN impact on NAD+ levels in the liver are below.

* Note:  These charts are somewhat deceptive. It shows NAM (green bar) elevated NAD+ nearly as much as NR (black bar)

However if they used equal mg of each supplement, which is how people actually purchase and use them, it would show NA about equal with NR and NAM far effective than NR at elevating NAD+ in the liver.

Mice in these experiments didn’t receive equal WEIGHTS of each precursor. Instead researchers chose to use quantity of molecules, which makes NR look “better” by comparison.

In this case, “185 mg kg−1 of NR or the mole equivalent doses of Nam and NA”(16).

Molecular weight for NR is 255 grams, NAM is 122 grams, and NA 123 grams.  So this chart used a ratio of  255 grams of NR to 122 and 123 grams of NAM and NA.

NMN

  • “NMN makes its way through the liver, into muscle, and is metabolized to NAD+ in 30 minutes” (R)

NR

  • Is much slower, taking 8 hours to reach peak NAD+ in humans (R)

NAM

  • Has very similar NAD+ profile to NR, taking 8 hours to reach peak NAD+ in humans (R)
  • Has been shown to increase NAD+ level in liver (47%), but was weaker in kidney (2%), heart (20%), blood (43%) or lungs (17%) (R)

NA (Niacin)

  • Elevates NAD+ to peak levels in liver in 15 minutes (R)
  • raised NAD+ in liver (47%), and impressively raised kidney (88%), heart (62%), blood (43%) and lungs (11%) (R)

TRYPTOPHAN

  • In the liver  tryptophan is the preferable substrate for NAD+ production (R)
  • Administration of tryptophan, NA, or NAM to rats showed that tryptophan resulted in the highest hepatic NAD+ concentrations(R)

ONLY NMN BYPASSES THE NAMPT BOTTLENECK IN TISSUES THROUGHOUT THE BODY

Restoring NAD+ to youthful levels in ALL CELLS throughout the body is the goal.

However, many tissues cannot utilize NAD+ directly from the blood as NAD+ cannot readily pass through the cellular membrane.

Muscle tissue, for example, depends on cells internal recycling of NAD+ through the salvage pathway which is controlled by Nampt.

To restore depleted NAD+ levels in such cells, a precursor must:

  • Be available in the bloodstream
  • Once inside a cell, be able to bypass the Nampt bottleneck

NA and Tryptophan
NA and Tryptophan act through the De Novo pathway, which supplies a small percentage of our NAD+, primarily in the liver

NAM
NAM is abundant in the blood and easily carried into such cells throughout the body, but  depends on Nampt, which is the rate limiting enzyme in the salvage pathway.

NR
When taken orally as a supplement, most NR does not make it through the digestive system intact, but is broken down to NAM (97,98,99).

For more info on how NR is converted to NAM in the body.

NR can bypass the Nampt bottleneck, but is not normally available in the bloodstream

After oral NMN supplementation, levels of NMN in the bloodstream are quickly elevated and remain high longer than NAM, NA, or NR (18,22,97,98,99)

Oral NMN supplements:

  • Make their way intact thru the digestive system (22)
  • Quickly elevates levels of NMN in the bloodstream for use throughout the body (22)
  • Quickly elevates levels of  NMN in tissues throughout the body (22)
  • Quickly raises levels of NAD+ in blood, liver and tissues  through the body (22,23)
  • Remain elevated longer than NAM, NA, or NR (18)

Only NMN is readily available in the bloodstream to all tissues, and bypasses the Nampt bottleneck in the Salvage pathway

ORAL NMN IS READILY AVAILABLE THROUGHOUT THE BODY

The chart at right shows levels of a double labeled NAD+ (C13-d-nad+) in liver and soleus muscle at 10 and 30 minutes after oral administration of double labeled NMN.

This clearly shows that NMN makes it way through the liver intact, through the bloodstream, into muscle, and is metabolized to NAD+ in 30 minutes (22) .

This quote below is directly from that study.

Orally administered NMN is quickly absorbed, efficiently transported into blood circulation, and immediately converted to NAD+in major metabolic tissues (22).

NMN QUICKLY RAISES NAD+ IN LIVER AND BLOOD

mouse-single-dose
In this 2016 study, mice were given a single dose of  NMN in water.

NMN  levels in blood showed it is quickly absorbed from the gut into blood circulation within 2–3 min and then cleared from blood circulation into tissues within 15 min

 

 

 

NMN INCREASES NAD+ and SIRT1 DRAMATICALLY IN ORGANS

In this 2017 study, NMN supplementation for 4 days significantly elevated NAD+ and SIRT1, which protected the mice from Kidney damage.

NAD+ and SIRT1 levels were HIGHER in OLD Mice than in YOUNG Mice that did not receive NMN.

LONG TERM SUPPLEMENTATION WITH NMN

mouse-long-term-research

In a long-term experiment documented in the 2016 study (22) , mice were given 2 different doses of NMN over 12 months.

Testing revealed that NMN  prevents some aspects of  physiological decline in mice, noting these changes:

  • Decreased body weight and fat
  • Increased lean muscle mass
  • Increased energy and mobility
  • Improved visual acuity
  • Improved bone density
  • Is well-tolerated with no obvious bad side effects
  • Increased oxygen consumption and respiratory capacity
  • Improved insulin sensitivity and blood plasma lipid profile

Here are some quotes from  the  study:

NMN suppressed age-associated body weight gain, enhanced energy metabolism, promoted physical activity, improved insulin sensitivity and plasma lipid profile, and ameliorated eye function and other pathophysiologies

NMN-administered mice switched their main energy source from glucose to fatty acids

These results strongly suggest that NMN has significant preventive effects against age-associated impairment in energy metabolism

NMN effectively mitigates age-associated physiological decline in mice


LOWER FAT AND INCREASED LEAN MUSCLE MASS

Researchers found that NMN administration suppressed body weight gain by 4% and 9% in the 100 and 300 mg/kg/day groups.

Analyses of  blood chemistry panels and urine did not detect any sign of toxicity from NMN.

Although health span was clearly improved, there was no difference in maximum lifespan observed.

These results suggest that NMN administration can significantly suppress body weight gain without side effects

INCREASED OXYGEN CONSUMPTION AND RESPIRATORY CAPACITY
screen-shot-2016-11-04-at-2-22-48-pm

Oxygen consumption significantly increased in both 100 and 300 mg/kg/day groups during both light and dark periods (Figure 3A).

Energy expenditure also showed significant increases  (Figure 3B).

Respiratory quotient significantly decreased in both groups during both light and dark periods (Figure 3C),

This suggests that NMN-administered mice switched their main energy source from glucose to fatty acids.

The mice that had been receiving NMN for 12 months exhibited energy levels, food and water consumption equivalent to the mice in the control group that were 6 months younger.

NMN administration has significant preventive effects against age associated physical impairment

HUMAN STUDIES – LONG TERM SUPPLEMENTATION WITH NMN

The first clinical trial of NMN in humans is currently underway by an international collaborative team between Keio University School of Medicine in Tokyo and Washington University School of Medicine (33).

Participants are 50 healthy women between 55 and 70 years of age with slightly high blood glucose,BMI and triglyceride levels.

Using a dose of 2 capsules of 125mg NMN per day over a period of 8 weeks, researchers are testing for:

  • change in insulin sensitivity
  • change in beta-cell function
  • works to control blood sugar
  • blood vessels dilate
  • effects of NMN on blood lipids
  • effects of NMN on body fat
  • markers of cardiovascular and metabolic health

According to the study:

“Data from studies conducted in rodents have shown that NMN supplementation has beneficial effects on cardiovascular and metabolic health, but this has not yet been studied in people”

Testing of metabolic parameter will continue for 2 years after supplementation has ended, so final results will not be published for some time yet, but preliminary results are expected to be announced in early 2018.

FOODS THAT CONTAIN NMN

NMN is found in many food sources such as edamame, broccoli, cucumber,cabbage, avocado, tomato, beef and shrimp.

As such, it is likely free from serious side effects in humans, and has been available for purchase commercially for over 2 years.

DOSAGE

In the long term (12 month) 2016 mouse study (22), both 100 and 300mg/kg per day improved oxygen consumption, energy expenditure, and physical activity more.

According to the FDA guidelines, an equivalent  would be about 560 mg for a 150lb human.

It should be noted that NMN administration did not generate any obvious toxicity, serious side effects, or increased mortality rate throughout the 12-month-long intervention period, suggesting the long-term safety of NMN.

The current Human study uses a dosage of 2 capsules of 125 mg, which seems to be the most commonly used dosage.

SUMMMARY

NAD+ levels decrease throughout the body as we age, contributing to disease and aging.

Restoring NAD+ levels can ameliorate many age released health issues.

All the NAD+ precursors are effective at raising NAD+ levels in the liver.

Raising NAD+ in the liver has many benefits, but is not effective in tissues and organs that cannot access NAD+ directly from the bloodstream and so depend on internal cellular NAD+ recycling.

For these tissues, utilizing each cells internal Salvage Pathway is necessary to restore NAD+ levels.

NR is not stable in the body and not normally found in the bloodstream, so is not readily available as NR to many tissues. Once metabolized to NAD+ it cannot enter cells. If metabolized to NAM it cannot bypass the Nampt bottleneck.

NMN is the only precursor that is stable and available to cells through the bloodstream, and can bypass the Nampt bottleneck to quickly restore NAD+ throughout the body.

NMN IS THE WHOLE BODY NAD+ BOOSTER

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OTHER RESEARCH WITH NMN

Aging

Head to Head Comparison of Short-Term Treatment with the NAD(+) Precursor Nicotinamide Mononucleotide (NMN) and 6 Weeks of Exercise in Obese Female Mice (Uddin, 2016)

NAD(+) levels were increased significantly both in muscle and liver by NMN
NMN-supplementation can induce similar reversal of the glucose intolerance
NMN intervention is likely to be increased catabolism of fats
NMN-supplementation does mimic exercise

DNA Damage

A conserved NAD+ binding pocket that regulates protein-protein interactions during aging (Sinclair, 2017)

This study showed supplementation with NMN was able to repair the DNA in cells damaged by radiation.

the cells of old mice were indistinguishable from young mice after just one week of treatment.”


Diabetes & Metabolic disease

Nicotinamide Mononucleotide, a Key NAD+ Intermediate, Treats the Pathophysiology of Diet- and Age-Induced Diabetes in Mice (Yoshino, 2011)

NMN was immediately utilized and converted to NAD+ within 15 min, resulting in significant increases in NAD+ levels over 60 min

administering NMN, a key NAD+ intermediate, can be an effective intervention to treat the pathophysiology of diet- and age-induced T2D

Surprisingly, just one dose of NMN normalized impaired glucose tolerance

Declining NAD+ Induces a Pseudohypoxic State Disrupting Nuclear-Mitochondrial Communication during Aging (Gomes, Sinclair,2013)

raising NAD+ levels in old mice restores mitochondrial function to that of a young mouse

treatment of old mice with NMN reversed all of these biochemical aspects of aging

restore the mitochondrial homeostasis and key biochemical markers of muscle health in a 22-month-old mouse to levels similar to a 6-month-old mouse

CardioVascular Disease

Nicotinamide mononucleotide, an intermediate of NAD+ synthesis, protects the heart from ischemia and repercussion (Yamamoto, 2014)

NMN significantly increased the level of NAD+ in the heart

NMN protected the heart from I/R injury

Nicotinamide mononucleotide supplementation reverses vascular dysfunction and oxidative stress with aging in mice (de Picciotto, 2016)

NMN reduces vascular oxidative stress
NMN treatment normalizes aortic stiffness in old mice
NMN represents a novel strategy for combating arterial aging

Short-term administration of Nicotinamide Mononucleotide preserves cardiac mitochondrial homeostasis and prevents heart failure (Zhang, 2017)

NMN can reduce myocardial inflammation

NMN thus can cut off the initial inflammatory signal, leading to reduced myocardial inflammation

Nicotinamide mononucleotide requires SIRT3 to improve cardiac function and bioenergetics in a Friedreich’s ataxia cardiomyopathy model

Remarkably, NMN administered to FXN-KO mice restores cardiac function to near-normal levels.

restoration of cardiac function and energy metabolism upon NMN supplementation
remarkable decrease in whole-body EE and cardiac energy wasting

Neurological Injury

Nicotinamide mononucleotide attenuates brain injury after intracerebral hemorrhage by activating Nrf2/HO-1 signaling pathway (Wei, 2017)

NMN treats brain injury in ICH by suppressing neuroinflammation/oxidative stress

NMN treatment protects against cICH-induced acute brain injury
NMN treatment reduces brain cell death and oxidative stress
These results further support the neuroprotection of NMN/NAD+

Alzheimers

Effect of nicotinamide mononucleotide on brain mitochondrial respiratory deficits in an Alzheimer’s disease-relevant murine model (Long, 2015)

We now demonstrate that mitochondrial respiratory function was restored

Nicotinamide mononucleotide protects against β-amyloid oligomer-induced cognitive impairment and neuronal death (Wang, 2016)

NMN could restore cognition in AD model rats.
The beneficial effect of NMN is produced by ameliorating neuron survival, improving energy metabolism and reducing ROS accumulation.
These results suggest that NMN may become a promising therapeutic drug for AD

Nicotinamide mononucleotide inhibits JNK activation to reverse Alzheimer disease(Yao, 2017)

NMN Treatment Rescues Cognitive impairments
NMN Treatment Improves Inflammatory Responses

Kidney Disease
Nicotinamide Mononucleotide, an NAD+ Precursor, Rescues Age-Associated Susceptibility to AKI in a Sirtuin 1-Dependent Manner (Guan, 2017)

Supplementation with NMN restored kidney SIRT1 and NAD+ content in 20-month-old mice and protected both young and old mice from acute kidney injury.

References:

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Nicotinamide Riboside Optimum Dosage

dosageNicotinamide Riboside (NR) is a form of vitamin B3 closely related to Niacin that is showing great promise for it’s ability to raise  NAD+ levels in older humans, back to the levels normally found in youth to prevent and repair damage to various organs in the body.

NAD+   is a key co-enzyme that enables the mitochondria to power and repair damage in every cell of our bodies.

WHAT IS THE MAXIMUM SAFE DOSAGE

There have been numerous studies of NR and NMN in mice that showed no negative side effects in Human Equivalent Dosages (HED) of 2.1 to 17 grams per day

The FDA recently granted GRAS (Generally Recognized as Safe) status on the basis of this clinical study, which showed “no observed adverse effect level was 300 mg/kg/day.”

screen-shot-2016-10-17-at-2-25-43-pmUsing the chart here from the  FDA guidelines for calculating this to HED of 2880 mg for a 130lb person.

With the FDA required 10x safety factor, that would equate to a dose of 288 mg per day for a 130lb human.

That is likely the limit on what sellers will recommend, but many people have been taking 500-1,000mg a day with no noticeable side effects.

[box]The 10x safety factor required by the FDA results in a safe dosage of 288 mg a day, although many people take much more and few if any side effects are reported at 1,000 mg a day or less[/box]

WHAT DOSAGE IS MOST EFFECTIVE

FIRST PUBLISHED RESEARCH ON NR IMPACT TO NAD+ IN HUMANS

The first published research to date that measures the NR supplementation increase in NAD+ levels in humans by Dr Charles Brenner is also documented in the Phd dissertation by Samuel AJ Trammel at the University of Iowa.

Experiment #1
In the first experiment, one Human subject was given a single dose 1,000 mg of NR each morning for 7 days. Blood levels of NAD+ and metabolites were 9 times the first day and every 24 hours thereafter.

screenshot-2016-09-08-09-20-24

From the results shown in chart above, we see NAD+ levels did not rise until 4 hours after ingesting, peaked at around 8 hours,  and remained elevated up to 24 hours.

Experiment #2
The second experiment involving human subjects included 12 individuals that were given 100,300, or 1,000 mg of NR with a washout period of 7 days between doses. Blood levels of NAD+ were recorded at 1, 2, 4, 8, and 24 hours.

nr_nad_24-hours

nr_nad_chart

100 mg per day
This chart shows 100mg per day (purple) elevates NAD+ levels around 4 hours, dropping significantly by 8 hours and continuing to decline throughout the 24 hours.

300 mg per day
The numbers in this line (red) are slightly elevated at 8 hours, then continue rising to 24 hours.

It appears that a dosage of 300mg achieved the same NAD+ increase as 1,000 mg at the 24 hour mark.

1,000 mg per day
This line (black) looks very similar to the first test with one subject given 1,000 mg daily.

Increased NAD+ noted at 4 hours, with maximum increase reached around 8 hour. It appears NAD+ levels remain at that maximum through 24 hours.

We can see that at all dosages the NAD+ levels were elevated somewhat within 4 hours.

It does appear an upper limit was reached after which, additional NR did not raise NAD+ any further.

Dr Brenner points to the increased NAAD levels that coincide with the peak of NAD+ and suggest NAAD acts as an “overflow pool”, that may later be converted to NAD+ if needed.

Do other Metabolites of NAD+ matter?
The author notes that supplementation with Nicotinamide Riboside elevates the level of many NAD+ metabolites at different rates:

“Because every NAD+ metabolite can be converted to one or more other metabolites, snapshots of the levels of NAD+ , nicotinamide (Nam) or any other NAD+ metabolite without assessment of the NAD+ metabolome on a common scale has the potential to be misleading.”

NAAD is much higher in the 1000mg subjects. However, the first study implies there is a limit to the possible increase of NAD+. Despite repeated usage over seven days, NAD+ tops out.

The second study shows that at 24 hours, NAD+ is elevated by approximately the same amount in the 300mg and 1,000mg test subjects.

[box]Conclusion: The maximum effect appears to be achieved at some dosage around 300mg per day.

Note: Subjects in this study were healthy and between 30-55 years of age. Older, sicker subjects might benefit from higher dosages. The Elysium Basis testing with older individuals (below) will hopefully shed more light on this.[/box]

SECOND STUDY OF NR EFFECT – ELDERLY PATIENTS TAKING ELYSIUM HEALTH BASIS

niagen_basis_elysiumResearch to prove Benefits and Safety for Elysium Health Basis brand of Nicotinamide Riboside

This recently complete, but not yet published study tracked 120 elderly subjects (60-80yrs age) over 8 weeks monitored blood and heart parameters to ensure safety.

They also measured NAD+ levels and several physical performance tests.

Completed in July 2016 but not yet published, it was sponsored by Elysium Health, manufacturer of Basis Nicotinamide Riboside.

A single capsule of BASIS is 125 mg of Chromadex NIAGEN brand of Nicotinamide Riboside, along with 50 mg of Chromadex Pterostilbene.

Participants received either placebo, 1, or 2 capsules of BASIS

Elysium Health did issue a press release that states that 125 mg of NIAGEN resulted in a 40% increase in blood NAD+ levels that was maintained throughout the 8 weeks of the study.

The 250 mg dosage resulted in an increase that was “significantly higher” than the 125 mg dose, and reached 90% at one of the 4 checkpoints (4 weeks).

Since the increase from the 250 mg dosages reached a plateau at 4 weeks, and dropped afterwards, implies that a higher dosage probably would not be any more effective.

This rather speculative interpretation agrees with the results in Study #1 that the most effective dosage is higher than 125 mg, but has peaked out at 250mg a day

[box]Conclusion: Most people will likely get the maximum NAD+ increase at 250mg per day
[/box]

 

NAD+ METABOLISM IN HUMANS

NAD+ is synthesized in humans by several different molecules (precursors), thru 2 different pathways:
De Novo Pathway

  • Tryptophan
  • Nicotinic Acid (NA)

Salvage Pathway

  • NAM – Nicotinamide
  • NR – Nicotinamide Riboside
  • NMN – Nicotinamide MonoNucleotide

The NAD+ supply is not stagnant – it is constantly being consumed and replenished, with the entire NAD+ pool being turned over 2-4 times per day (14).

This recycling is through the salvage pathway, where the enzyme Nampt catalyzes NAM to NMN, which is then metabolized to NAD+.


Nampt is the rate-limiting step in the salvage process (97).

Many studies have confirmed the importance of Nampt in maintaining sufficient NAD+ levels, such as the quote below from a 2016 study that used mice lacking Nampt in muscle fiber:

“NAD content of muscle was decreased by ~85% confirmed the prevailing view that the salvage route of NAD synthesis from NAM sustains the vast majority of the NAD” (97)

These mice exhibited normal muscle strength and endurance while young, but deteriorated rapidly as they aged which confirmed Nampt is critical to maintaining NAD+ levels.

As we age, Nampt enzyme activity is lower, resulting in less NAM recycling, less NAD+, more disease and aging (97,101).

NMN and NR SUPPLEMENTS CAN BYPASS NAMPT

NR had been known for decades, but was not thought to be that important until 2004 when Dr. Charles Brenner discovered the enzyme NRK1 can phosphorylate NR directly to NMN, bypassing the Nampt “bottleneck” (100).

This newly discovered “shortcut” in the NAD+ salvage pathway found that NR can be metabolized directly to NMN to boost NAD+ levels more effectively than NAM.

MOST NR IS FIRST METABOLIZED TO NAM

When taken orally as a supplement, most NR does not make it through the digestive system intact, but is broken down to NAM (97,98,99).

Even when taken at very high dosages, NR has not been detected in the bloodstream in any research (97,98,99).

“This evidence indicates that NR is converted to NAM before absorption occurs and that this reaction is the rate-limiting step ” (98)

“NR has been shown be converted to Nam before being absorbed or reaching tissues” (99)

“we were surprised to find that NR exerts only a subtle influence on the steady state concentration of NAD in muscles. Our tracer studies suggest that this is largely attributable to breakdown of orally delivered NR into NAM prior to reaching the muscle. ” (97)

Note:NAM does elevate NAD+, but is on the “wrong” side of the Nampt bottleneck, which limits it’s effectiveness

HUMAN STUDY ON NR BIOAVAILABILITY

The following five charts are all from the thesis published by Samuel Alan Trammell in 2016 under supervision by Dr Brenner:

Nicotinamide riboside is uniquely and orally bioavailable in mice and humans


This chart above shows the impact on NAD+ metabolites over time for a 52 year old human after ingesting 1000mg of NR daily for 7 days.

NAD+ levels begin to rise at 4.1 hours, and peak at 8.1 hours.

NAM levels double at .6 hours and have a second peak at 7.7 hours, long before NAD+ levels are elevated.

This chart at right shows metabolites found in urine of the subject from the same experiment as above.

The red box shows NAM  is elevated more than 10x baseline at the same time point that NAD+ is elevated, which implies that NR has elevated NAM to such an extent that excess NAM is excreted in urine.


This chart a left shows impact of NR, NA, and NAM supplementation on blood plasma NAD+ (b), and NAM  (d) levels in 12 human subjects.

The red line at 2 hours shows NR supplementation increases NAM perhaps 3x (d), but has not yet elevated NAD+(b).

The 2 hour mark also is the point at which NAM supplementation begins to increase NAD+ levels (b).

The blue line at 8 hours is when both NR (b) and NAM (d) supplementation reach peak NAD+ increase.

Lastly, the green bar and black bar in chart b show that NAM elevates NAD+ slightly less than NR.

NR elevated NAD+ slightly more than NAM, but is much slower acting

MOUSE STUDIES ON NR BIOAVAILABILITY


The chart above shows the result on NAD+ metabolism of 15 mice fed NR by oral gavage at a dose of 185 mg/kg of bodyweight.

The NR was synthesized with heavy atoms of deuterium at the ribosyl C2 and 13C on the Nam side, to allow tracking.

The measurement at 2 hours shows 54% of the NAD+ has the single heavy molecule (white bar, M+1). This 54% was likely broken down to NAM first, losing the second labelled heavy atom.

At the same time point, 5% of the NAD+ had both labels (Grey bar, M+2).

This 5% of NR made it through the digestive tract intact and was metabolized through the shortcut from NR -> NMN -> NAD+, vs 54% that had been through NR -> NAM -> NMN -> NAD+.

The chart above shows the impact of the same double labeled NR on mouse liver, but this time after IP (Intraperitoneal) Injection.

Note the dramatic difference in the ratio of labelled M+2 over M+1. IP results in much higher levels of intact NR (M+2) being metabolized to NAD+, whereas Oral NR shows far more M+1 labelled NR to NAD+.

This different behavior in IP vs oral NR supplementation also implies oral NR is partially metabolized to NAM before conversion to NAD+.

The above chart shows the resultant increase in select NAD+ metabolites of mice fed NR (unlabeled) at 185 mg/kg of bodyweight.

As noted by the authors, NR and NAR are the only NAD+ precursors tested that did NOT result in elevated levels of the precursor in the liver.

Here is one last quote in discussion section from the Trammell thesis:

“NR has not been detected in the blood cell fraction nor in plasma …NR varied and displayed no response to NR administration … but was detected after IP of double labeled NR in liver (Figure 5.7) and muscle (Figure 5.9), revealing NR does circulate”

They are saying that NR is found in small quantities in the liver, but is not detectable in bloodstream.  Oral supplementation with NR did not show any increase in NR in the body.  However, Injection (IP) of NR does result in a detectable increase of NR in muscle and Liver. So NR does circulate in the bloodstream when injected, but has not yet been detected upon oral supplementation.

The timing and amplitude of the increases in metabolites noted above imply that:

  • Oral NR does not result in a detectable increase of NR in the body
  • It’s likely a majority of the increase in NAD+ is due to NR->NAM->NAD+.

Note: NAM does elevate NAD+, but is on the “wrong” side of the Nampt bottleneck, which limits it’s effectiveness

DOSAGE – SUMMARY

Further testing with larger sample sizes and more data points is underway that will give a much better estimate on the most effective dosage. For now, some conclusions on dosage we see are:

  • A single dose of NR does increase NAD+ levels
  • NAD+ levels remain elevated 24 hours after a single dose.
  • There is an upper limit on the increase of NAD+ levels with NR supplementation
  • Maximum NAD+ elevation is maintained at a dosage higher than 125 mg per day – likely close to 250mg per day
  • It appears that a single daily dose may be just as effective as 2  smaller dosages.

Most NR ends up as NAM after digestion, so is much slower and less effective than NMN.

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References:

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Lycopene a great natural sunscreen

lycopeneSunscreen is not only applied to your skin, your body also makes its own. It’s called melanin.

But that’s not all. Growing evidence indicates that carotenoids, the antioxidants responsible for the vivid colors of many fruits and vegetables, may provide added protection from the sun.

A recent study investigated the effects of taking carotenoid supplements — lycopene and lutein — on skin protection at the molecular level. Here is a detailed summary of its findings.

 

Background

Carotenoids are a diverse group of antioxidant plant compounds that are responsible for the red, orange and yellow colors of many fruits and vegetables.

Several studies show that they may protect the skin against harmful sunlight.

Beta-carotene, which can be converted to vitamin A, is the most extensively studied carotenoid. A meta-analysis of seven controlled trials concluded that taking beta-carotene supplements may protect against sunburns and reduce their severity (1).

Carotenoids other than beta-carotene may also act in a similar way.

One study showed that taking 24 grams of a mixed carotenoid supplement containing equal amounts of beta-carotene, lycopene and lutein protected the skin as much as 24 grams of beta-carotene alone (2).

Another 10-week trial found that consuming tomato paste, providing 16 mg per day of lycopene, significantly reduced sunburns, compared to a placebo (3).

However, lycopene may not be the only plant compound in tomatoes providing benefits. Taking a supplement containing a combination of plant compounds from tomatoes led to better protection against sunburns than lycopene alone (4).

Article Reviewed

This was a randomized controlled trial investigating the effects of lycopene and lutein supplements on genes associated with sunburns.

Molecular evidence that oral supplementation with lycopene or lutein protects human skin against ultraviolet radiation: Results from a double-blinded, placebo-controlled, cross-over study.

Study Design

This randomized, double-blind crossover trial examined the capacity of the carotenoids lycopene and lutein to protect the skin against harmful sun radiation.

It was divided into two parts:

Part 1: Lycopene

A total of 29 people (25 men and 4 women) completed part 1. They were assigned to two 3-month treatment periods in a random order.

  • Lycopene: Every day the participants took four capsules containing a lycopene-rich tomato extract providing 5 mg of lycopene, as well as other plant compounds, such as phytoene, phytofluene, tocopherols and phytosterols.
  • Placebo: Capsules containing soy bean oil were taken instead of lycopene.

Part 2: Lutein

A total of 30 people (23 men and 7 women) completed the lutein arm of the study. They were assigned to two 3-month treatment periods in a random order.

  • Lutein: Every day the participants took two capsules containing 10 grams of lutein stabilized by 10% carnosic acid.
  • Placebo: Capsules containing soy bean oil were taken instead of lutein.

Before each study period, there was a 2-week washout period to reduce any possible carry-over effects from the previous period or the participants’ regular diets.

To investigate the carotenoids’ effects on the skin’s ability to protect itself against harmful light, the following procedure was conducted at the start and end of each treatment period.

  1. The researchers started by irradiating a patch of each participant’s skin with two types of ultraviolet light — ultraviolet B (UVB/A-) and ultraviolet A (UVA1) — using a solar simulator.
  2. 24 hours later, they took a skin biopsy from the irradiated area. For comparison, they also took a biopsy from a skin area that was not exposed to ultraviolet light.
  3. Finally, they analyzed the skin samples for the expression of genes that are associated with oxidative stress and sunburns.
  4. These genes were heme oxygenase-1 (HO-1), intercellular adhesion molecule-1 (ICAM-1) and matrix metalloproteinase-1 (MMP-1).

In addition, the researchers measured the carotenoid levels in the participants’ blood.

Bottom Line: This was a randomized controlled trial examining the effects of supplements containing a lycopene-rich tomato paste or lutein on the expression of genes associated with sunburns.

Finding: Lycopene and Lutein May Protect Against Sun-Induced Skin Damage

Supplementing with lycopene or lutein significantly increased blood levels of these carotenoids.

Additionally, exposure to ultraviolet light increased the activity of genes linked to oxidative stress and sunburns (HO-1, ICAM-1 and MMP-1).

However, the researchers discovered that taking lycopene or lutein supplements reduced the activity of these genes, compared to placebo.

The findings indicate that these carotenoids may protect the skin against damage and premature aging caused by sun exposure. The protective effect was similar after both types of ultraviolet light (UVB/A-and UVA1).

It also didn’t matter if the lycopene was given in the first or second phase of each study arm.

However, the protective effect of lutein was significantly weaker, compared to lycopene, if it was given in the second phase. That is, after a placebo period.

On the other hand, there were no differences between lycopene and lutein when they were given in the first phase.

These findings are supported by controlled trials showing that lycopene may reduce sunburns, as well as the harmful effects of sunlight on the molecular level (356).

Why carotenoids work in this way is currently unknown, but some scientists believe it may have something to do with their antioxidant properties.

Bottom Line: The study found that the carotenoids lycopene and lutein may protect the skin against harmful ultraviolet sunlight.

Limitations

This study had an excellent design. However, it had one fault — the short washout periods between treatments.

The purpose of washout periods is to prevent carry-over effects from a previous treatment or the participants’ habitual diets. Their insufficient length is often a weakness of crossover trials.

In the current study, the length of the washout periods appeared to be reasonably long, based on previous studies (78).

However, the protective effects of lutein were significantly weaker when it was given after 16 weeks of a lutein-restricted diet, indicating that the washout periods might not have been long enough.

Summary and Real-Life Application

In short, this study showed that dietary intake of lutein and lycopene may protect the skin against harmful sunlight, possibly slowing skin aging and reducing the risk of skin cancer.

Although the findings are very promising, further studies are needed before any definite health claims can be made.

Nevertheless, eating tomatoes, watermelons, bell peppers, kale or other carotenoid-rich fruits and vegetables is definitely a good idea if you spend a lot of time in the sun.

Keto diet proven effective for diabetics

ketogenic-dietMany nutritionalists and dietitians are joining the chorus of fans of ketogenic diet. And certainly it is more effective that even the best diet pills like Garcinia Cambodia.

However, there are some health professionals concerned about the use of ketogenic diets for diabetics.

Addressing this concern, a recent randomized controlled trial investigated the safety, tolerability and effectiveness of a 4-month, very low-calorie ketogenic diet in 89 obese people with type 2 diabetes.

Here is a detailed summary of its findings, in addition to some background information.

 

Background

low-carb-snacks-1200x509The ketogenic diet contains minimal amounts of carbs.

This forces the body to burn fat and leads to ketosis, which is characterized by elevated levels of ketone bodies in the blood. The ketone bodies partially replace glucose (blood sugar) as fuel for cells.

Reducing sugar intake has multiple health benefits, especially for diabetics.

Additionally, eating sugar, especially sugar-sweetened beverages, may promote overeating. Sugar may also be addictive for some people, making them susceptible to cravings and overeating.

For these reasons, high sugar intake is probably one of the main causes of weight gain and obesity.

A ketogenic diet eliminates most dietary sugar, as well as the health problems associated with it. However, eliminating dietary carbs means that you have to eat more fat or protein instead.

Increasing fat intake doesn’t seem to be a problem if the diet is also calorie-reduced. Studies indicate that high-fat diets are more effective for weight loss than low-fat diets. This is probably because high-fat diets contain much fewer carbs (1).

Additionally, limiting carbs is more beneficial for weight loss and blood sugar control, compared to a low-fat diet or high-carb diet (23).

Yet, some researchers are concerned that a high protein intake on a very low-carb diet may adversely affect diabetic people with kidney problems (diabetic nephropathy) (45).

Others have pointed out that very low-carb or high-protein diets may not be feasible in a real-life setting (6).

In 2008, the American Diabetes Association even concluded that very low-carb diets were of limited use for people with diabetes and should only be considered as part of a structured weight loss program (7).

However, few studies have examined the safety and effectiveness of a calorie-reduced, very low-carb ketogenic diet, compared to a standard weight loss diet.

Article Reviewed

This study examined the safety and effectiveness of a low-calorie ketogenic diet in obese diabetics.

Short-term safety, tolerability and efficacy of a very low-calorie-ketogenic diet interventional weight loss program versus hypocaloric diet in patients with type 2 diabetes mellitus.

screen-shot-2016-10-26-at-8-43-58-am

Study Design

This randomized controlled trial evaluated the safety, tolerability and effectiveness of a low-calorie ketogenic diet in obese people with type 2 diabetes.

A total of 89 men and women, aged 30–65, participated in the study. They followed a 4-month weight loss program, which included lifestyle and behavioral modification support.

The participants were randomly assigned to one of two groups:

1. Very Low-Calorie, Ketogenic Diet (VLCK)

This was a commercial weight loss program (DiaproKal Method) based on specific protein supplements provided by Pronokal Protein Supplies in Spain.

The program consisted of three stages:

  1. Active phase: Very low-calorie diet (600–800 calories per day) containing less than 50 grams of carbs from vegetables and 10 grams of olive oil. Protein intake ranged between 0.36–0.55 grams per pound of body weight (0.8–1.2 g per kg).
  2. Metabolic stabilization: When the participants had reached a pre-specified weight loss target, they began a low-calorie diet and gradually started to incorporate different food groups.
  3. Maintenance phase: Finally, the participants went on a weight maintenance diet that was balanced in carbs, protein and fat and ranged between 1,500–2,250 calories per day.

2. Standard Low-Calorie Diet (Control)

This was a standard weight loss diet based on the American Diabetes Association Guidelines (8).

It aimed at reducing calorie intake by 500–1,000 calories per day, depending on the participants’ basal metabolic rate.

The diet provided 10–20% of calories from protein, 45–60% from carbs and less than 30% of calories from fat.


In both groups, the participants attended nine individual support sessions with a dietitian and were contacted by telephone twice a month.

The researchers measured the participants and took blood samples on four occasions: 1) at the start of the study, 2) after 2 weeks, 3) after 2 months, and 4) at the end of the study (after 4 months).

They measured the following parameters:

  • Renal function: Biomarkers of kidney function were measured in blood samples.
  • Liver function: Biomarkers of liver function were measured in blood samples.
  • Ketones: Levels of ketone bodies in blood samples were measured to confirm that those in the VLCK reached ketosis.
  • Body weight, body mass index and waist circumference.
  • Blood sugar control: Fasting blood sugar, insulin and HbA1c were measured in blood samples. Insulin resistance was calculated using the homeostasis model assessment (HOMA).
  • Blood lipids: Fasting triglycerides, total cholesterol and LDL cholesterol.
  • Dietary adherence: Assessed using the Eating Self-Efficacy Scale.

Conclusion: This was a randomized controlled trial examining the safety and effectiveness of a calorie-reduced, very low-carb ketogenic diet in obese people with type 2 diabetes.

Finding 1: The Ketogenic Diet Caused Greater Weight Loss

The participants in the VLCK group lost an additional 22 lbs (10 kg) of body weight, compared to the control group.

Specifically, they lost 32 lbs (15 kg) in the VLCK group and 11 lbs (5 kg) in the control group.

They also experienced a greater decrease in waist circumference, as shown in the chart below.

keto-diet-chart

Some researchers have speculated that the ketogenic diet helps people lose weight only because it’s much higher in protein than the standard weight loss diet.

Eating high amounts of protein is known to reduce appetite and increase the amount of calories burned.

One study suggests that going on a ketogenic diet without increasing protein intake has no lasting effect on the amount of calories burned and doesn’t lead to additional weight loss, compared to a standard, high-carb weight loss diet.

Conclusion: The ketogenic diet led to significantly greater weight loss than the standard low-calorie diet.

Finding 2: The Ketogenic Diet Led to Greater Improvements in Blood Sugar Control

Insulin resistance decreased significantly more in the VLCK group, compared to the control, as shown in the chart below.

keto-diet-insulin-charg

Fasting blood sugar levels reduced similarly in both groups.

However, the decrease in HbA1c was significant only in the VLCK group. HbA1c is a marker of blood sugar control that represents the previous 3-month average of blood sugar levels.

These findings are supported by previous studies showing that very low-carb diets improve blood sugar control in diabetics (910).

Conclusion: The ketogenic diet significantly improved blood sugar control, compared to a standard weight loss diet.

Finding 3: Self-Reported Adverse Effects Were More Common on the Ketogenic Diet

The researchers detected no significant differences in safety parameters between groups. However, self-reported adverse effects were more common in the VLCK group.

Mild adverse effects were reported by 80% of the participants in the VLCK group but only 41% of those in the control group. These included headache, nausea, vomiting and weakness.

Additionally, constipation and low blood pressure when standing up (orthostatic hypotension) were more common in the VLCK group at the end of the study. No serious adverse effects were reported.

Adverse effects became less frequent as the study progressed. The authors concluded that the ketogenic diet is a safe, well-tolerated weight loss method for people with type 2 diabetes.

The adverse effects reported in this study are similar to those generally associated with very low-carb diets (11).

Conclusion: Blood analyses revealed no significant differences in biomarkers of liver and kidney function between groups. However, self-reported adverse effects were more common in the VLCK group.

Limitations

Participants in the VLCK group received protein supplements provided by Pronokal Protein Supplies in Spain.

Additionally, five of the nine authors received research grants and advisory board fees from the company, creating a conflict of interest.

Otherwise, the study appears to have been well designed.

Summary and Real-Life Application

In conclusion, a weight loss program based on the ketogenic diet was significantly more effective than a standard weight loss program.

It appeared safe and reasonably well tolerated by people with type 2 diabetes and caused greater weight loss and improvements in blood sugar control.

Supplementation to correct NAD+ deficiency repairs vision damage in Mice

diabeticretinopathy1

Nicotinamide adenine dinucleotide (NAD+) is a coenzyme found in the cells of all living creatures (3,4) and is critical for communication between the cell nucleus and the mitochondria that power the cells (5,6,7)

LOWER NAD+ LEVELS AS WE AGE

Everyone experiences lower NAD+ levels throughout the body as we age, effecting the communication within every cell of our bodies.

Scientists have known for some time that this loss of NAD+ leads to many different age related diseases as the cells lose ability to perform basic tasks and repair damage due to oxidative stress. (8)

HEALTH ISSUES RELATED TO DECLINING NAD+ LEVELS

  • Neural cognitive dysfunction (1,2,3)
  • Decreased Energy and muscle strength (23,24)
  • Higher Blood Sugar Levels and Increased Insulin resistance (20,21,22)
  • Chronic Inflammation resulting in hypertension and heart disease( 12,13,14)
  • Fatty Liver Disease (NAFLD and AFLD)(15,16,17)
  • Increased belly fat (18,19)

[box]Conclusion: Declining NAD+ levels are implicated in many age related disease and chronic conditions[/box]

NAD+ DEFICIENCY IMPLICATED IN RETINAL DISEASE

In addition to the chronic age related diseases found to be related to declining NAD+ levels, the study below finds impaired NAD+ biosynthesis in many diverse retinal diseases among young and older mice.

NAMPT-Mediated NAD+ Biosynthesis Is Essential for Vision In Mice

This study published in cell magazine published sep 27, 2016 found that

  • Limiting the natural NAD+ synthesis in the photoreceptors in Mice results in loss of vision
  • Supplementation to increase NAD+ reverses the damage and restores vision
  • Mouse models of retinal dysfunction exhibit early retinal NAD+ deficiency
  • NAD+ deficiency causes retinal metabolic dysfunction

Vision depends on the 2 classes of photoreceptors the rods and cones. Many different diseases such as Retinitis Pigments (RP), Age-Related Macular Degeneration (AMD), Rod and Cone Dystrophies, and Leber Congenital Amaurosis (LCA) all attack the photoreceptors thru diverse pathways that lead to photoreceptor death and blindness.

Photoreceptors are known to have high energy requirements, but limited reserves so are dependent on constant synthesis of NAD+ to meet energy needs. (Ames et al., 1992, Okawa et al., 2008)

The authors theorized that NAD+ biosynthesis plays a key role in healthy vision. They noted that the leading cause of blindness in children, LCA, is caused by a mutation in the enzyme NMNAT1 which results in impaired synthesis of NAD+.(Falk et al., 2012, Koenekoop et al., 2012, Sasaki et al., 2015)

In mammals, NAM is catalyzed by nicotinamide phosphoribosyltransferase (NAMPT) as the first step in biosynthesis of NAD+.

In this study, researchers created knockout mice that lack NAMPt in rod photoreceptors which disrupts the normal NAD+ biosynthesis, resulting in a 26-43% reduction in retinal NAD+ levels.

Within 6 weeks, these mice exhibited significant photoreceptor death and vision loss. The results very closely matched the degeneration seen in patients with Retinitis Pigments and other degenerative vision disease.

According to the authors:

NAD+ deficiency caused metabolic dysfunction and consequent photoreceptor death…these findings demonstrate that NAD+ biosynthesis is essential for vision

SUPPLEMENTATION TO INCREASE NAD+ PREVENTS PHOTORECEPTOR DEGENERATION AND RESTORES VISION

screen-shot-2016-10-04-at-10-16-05-am
To confirm the cause of vision loss, researchers supplemented knockout mice with daily injections of NMN, bypassing the need for NAMPT in the first step of NAD+ synthesis. Those mice receiving NMN experienced significant recovery of retinal function.
(Figures 3A–3C).

These data clearly demonstrate that NAMPT-mediated NAD+ biosynthesis is necessary for the survival and function of both rod and cone photoreceptors, as promoting NAD+ biosynthesis in the retina with NMN supplementation can compensate for Nampt deletion, thereby reducing photoreceptor death and improving vision.

NAD+ DEFICIENCY IS COMMON IN MANY RETINAL DISEASES

screen-shot-2016-10-04-at-10-15-02-am

Researchers were able to determine that NAD+ deficiency is common in many vision problems.

Mice subjected to light exposure retinal damage had significant reduction in NAD+ levels (Figure 3H)

Similar reductions in NAD+ levels were found in mice with streptozotocin (STZ)-induced diabetic retinal dysfunction compared to non-hyperglycemic controls (Figure 3I).

Lastly, they compared 18-month-old vs 6 month old mice. As with the light exposed and diabetic induced mice, the older mice exhibited diminished vision along with decreased retinal NAD+ levels (Figure 3J).

These findings support the idea that NAD+ deficiency may be a shared feature of retinal dysfunction.

SUPPLEMENTATION TO INCREASE NAD+ PROTECTS VISION

screen-shot-2016-10-04-at-10-12-49-amAfter demonstrating that light induced retinal dysfunction was linked to decreased NAD+ levels, researchers were able to show that supplementation to increase NAD+ could protect against retinal damage.

Mice that were given injections of NMN for 6 days prior, and 3 days after light exposure exhibited improved retinal function vs those that did not receive NMN injections (Figures 4A–4C).

[box]Conclusion: Results from this study suggest that supplementation to increase NAD+ deficiencies can help repair macular damage and may be an effective treatment for many common degenerative vision problems.[/box]

IMPLICATIONS FOR HUMANS

David_Sinclair_solo_mid_0_0_4_1
This study was very specific for the impact of NAD+ on Retinal disease in Mice, but is also further evidence that the absence of sufficient NAD+ has dire consequences, and that replacement of NAD+ can repair damage.

Researchers are experimenting with various techniques for raising NAD+ levels in mice and humans such as:

NMN
The 2013 study by Dr David Sinclair that demonstrated increased levels of NAD+  reverses age related degeneration in mice also used injections of NMN (25).

You can read more about Nicotinamide Mono-Nucleotide (NMN) here.

NICOTINAMIDE RIBOSIDE
Other studies with mice and human subjects use supplementation with Nicotinamide Riboside (NR) to raise NAD+ levels.

NR is a precursor the body can use to manufacture NAD+. It has been shown to be safe and effective at raising NAD+ levels in humans in dosages of around 250mg a day.

CD38
Another approach to boosting NAD+ levels is preventing the drop in NAD+ levels in the first place.

Recent studies have demonstrated that the enzyme CD38 becomes elevated as we age, possibly in response to increasing inflammation levels, and corresponds with declining NAD+ levels.

QUERCETIN
Flavonoids such as Quercetin are proving effective at lowering CD38 levels which results in higher circulating levels of NAD+ in the bloodstream.

Dr Sinclair recently published this article on CD38 and concluded that:

    • Combating the rise of CD38 is a promising approach to protect NAD+ levels.
    • The efficacy of NAD+ precursors may be enhanced by co-supplementation with CD38 inhibitors
Conclusion: Inhibiting CD38 to prevent NAD+ destruction AND supplementing with NAD+ precursors so the body can create more NAD+ is a promising new avenue in the anti-aging battle

No, Butter is NOT bad for your heart health

butter-and-knife-on-wooden-chopping-boardFor the past decades, butter has been implicated as a significant cause of heart disease.

However, studies provide mixed results and whether butter truly increases the risk of chronic disease is hotly debated.

A recent meta-analysis examined how eating butter affects heart disease, type 2 diabetes and mortality risk. Here is a detailed summary of the findings.

 

Background

Butter is a dairy product made from cream. It is almost pure milk fat, which mainly consists of saturated fatty acids.

The role of butter in health and disease is uncertain and hotly debated. Several studies show that a high intake of saturated fat is linked with a poor blood lipid profile, which is a risk factor for heart disease.

Additionally, one controlled trial showed that a high intake of saturated palm oil, rich in palmitic acid, caused greater gains in belly fat and liver fat, compared to polyunsaturated fat (1).

However, the largest and most recent meta-analyses of observational studies suggest that reducing saturated fat itself has neutral effects on health, whereas replacing it with certain unsaturated fats may have benefits (2).

Additionally, growing evidence suggests that not all saturated fats are the same and demonizing saturated fats as a whole is an oversimplification.

Nevertheless, official dietary guidelines continue to recommend lower intakes of all saturated fat and higher intakes of non-hydrogenated unsaturated fat (3).

Studies suggest that butter is different from other sources of dairy fat. Specifically, the fat in butter is not enclosed in a milk fat globule membrane (MFGM).

Several randomized controlled trials show that eating butter fat has worse effects on the blood lipid profile than other sources of dairy fat with an intact MFGM, such as cream or cheese (456).

Whether these effects translate into an elevated risk of hard endpoints, such as heart attacks, remains unclear.

Article Reviewed

This meta-analysis examined the association between butter intake and heart disease, diabetes and all-cause mortality or death.

Is Butter Back? A Systematic Review and Meta-Analysis of Butter Consumption and Risk of Cardiovascular Disease, Diabetes, and Total Mortality.

Study Design

This was a systematic review and meta-analysis of prospective observational studies and randomized controlled trials examining the association of butter consumption with heart disease, diabetes and mortality.

The researchers searched scientific databases for all relevant studies that fulfilled the exclusion criteria. When conducting the analysis, they followed the Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines.

A total of 9 publications were selected, including a total of 636,151 participants. No randomized controlled trials with hard endpoints were found.

Bottom Line: This was a systematic review and meta-analysis of prospective observational studies investigating the association of butter with the risk of heart disease, diabetes and death.

Finding 1: Butter Was Weakly Linked With All-Cause Death

Two large observational studies assessing the links between butter consumption and all-cause mortality (death) were included in the meta-analysis. These studies included a total of 379,763 participants.

The analysis showed that the risk of death increased by 1% for each tablespoon (14 grams) of butter consumed daily.

Previous, large meta-analyses examining the effects of total saturated fat intake found no significant effects on overall mortality (27).

Bottom Line: The researchers discovered that for each tablespoon of butter eaten, the risk of death from any cause increased by 1%.

Finding 2: Butter Reduced the Risk of Diabetes

The analysis included four studies examining the links between butter consumption and type 2 diabetes. They included a total of 201,628 participants.

Pooling the findings from these studies, the researchers discovered that a higher intake of butter was linked with a modest decrease in the risk of developing type 2 diabetes.

Specifically, the risk of type 2 diabetes decreased by 4% for each tablespoon (14 grams) eaten daily.

Other observational studies have found no association between dairy fat and type 2 diabetes, but a few support the present results, reporting a reduced risk with higher intakes (891011).

Bottom Line: The study showed that each tablespoon of butter eaten daily reduced the risk of type 2 diabetes by 4%.

Finding 3: Butter Was Not Linked With Heart Disease

Five of the included studies investigated the association of butter with heart disease.

When their results were combined, butter intake was not significantly linked with heart disease, including stroke and coronary heart disease.

These findings are supported by previous meta-analyses (1213).

Bottom Line: The meta-analysis showed that butter was not significantly associated with the risk of developing heart disease.

Limitations

The main limitation of this meta-analysis was the observational design of the included studies. Observational studies cannot demonstrate causality.

Since high butter consumption is generally associated with unhealthy dietary patterns and lifestyle habits, the study might have overestimated the association of butter with mortality, and/or underestimated its links with type 2 diabetes.

Summary and Real-Life Application

This analysis suggests that butter is neutral when it comes to the risk of developing heart disease.

Additionally, it was associated with a lower risk of type 2 diabetes, but a slightly elevated risk of overall mortality. Since these findings were based on observational studies, they should be taken with a grain of salt.

It should be noted that the elevated mortality risk associated with butter is relatively small compared to many other foods, such as refined grains and sugar.

In conclusion, it seems there is no compelling reason to avoid butter. Moderate amounts should be fine. However, if you eat lots of it, it may be wise to replace some of it with oils that have proven health benefits, such as olive oil.

Does Frequent Snacking affect Weight Loss

pretzels-and-snacks-in-bowlsMany snack foods are unhealthy and easy to overeat.

In many cases, snack foods may contribute to the development of obesity. But does snacking itself affect body weight?

A recent review shows that cutting down on snacks may be as effective as popular weight loss supplements like Garcinia Cambodia. Below is an overview of its main points.

 

Article Reviewed

This review discussed how snacking affects satiety and body weight.

Snack Food, Satiety, and Weight.

What Are Snacks?

Snacks are any foods that are eaten between meals.

They often are ready-to-eat and do not require much preparation. These commonly include candy, chips, crackers, cookies, granola bars, nuts and popcorn.

Although beverages are usually not considered snack foods, they are consumed along with snack foods.

In this review, we place beverages under the broad definition of snack foods.

Bottom Line: Snacking is the act of consuming foods or beverages between meals.

Does Snacking Increase Weight Gain?

Snacking contributes to approximately 27% of the daily calorie intake among children. The percentage has been on the rise in recent decades in both children and adults (12).

The increased popularity of snacking goes hand in hand with increased screen time (watching TV and playing computer games) and less physical activity.

Additionally, highly processed, “unhealthy” snacks are the most popular, and there seems to be limited interest in healthy snacks in the general population (345).

For these reasons, unhealthy snacking often contributes to weight gain.

Bottom Line: Snacking may be largely responsible for weight gain among many people.

Is Snacking Healthy?

In general, nutrient-poor and calorie-rich snacks are considered unhealthy (67).

Unhealthy snacks include candy, chips, cookies and sugary beverages. Healthy snacks may include fruits, vegetables, nuts, seeds and whole grains.

That said, any snacks are unhealthy when snacking goes out of hand and starts contributing to excessive weight gain.

Studies also suggest that irregular eating habits, often associated with snacking, may adversely affect health.

Bottom Line: Healthy snacks can be very nutritious. However, snacking is unhealthy when it gets out of hand or involves unhealthy food.

What Factors Affect Snacking?

Snacking is affected by a variety of factors.

The following factors have been associated with snacking behavior:

  • Poor education: One study showed that snacking was more common among those from poorly educated families (8).
  • Knowledge: Being able to distinguish between healthy and unhealthy snacks affects food choice (9).
  • Emotional eating: Some people respond to negative emotions by eating, especially high-sugar, high-fat snacks (10).
  • Stress: Anxiety causes some people to snack, especially emotional eaters (10).
  • Family norms: One study showed that having strict parents reduced snacking among children (11).
  • Social norms: When young adults were led to believe that limiting junk foods was the social norm, their intake of high-calorie snacks decreased (12).
  • Availability: Limited access to healthy snacks affects intake (13).
  • Packaging: Bigger package sizes encourage overeating, regardless of people’s appetite or the taste of the snack (14).
  • Distractions: Mindful eating reduces snack intake, whereas distractions (like watching TV or playing a video game) increases it (15).
  • Variety: Having a wide variety of snacks to choose from can promote overeating (1617).

Bottom Line: Numerous factors influence snacking behavior, including how often people snack, when they do it and how much they eat.

How Do Snacks Affect Appetite?

Some researchers have speculated that eating snacks might promote fullness or satiety, thus reducing the risk of overeating at the next meal (18).

One study found that snacks are generally not very filling. However, of all the snacks evaluated, those with the highest protein content were the most satiating (19).

Another study found that a high-protein afternoon snack delayed the need for dinner, compared to high-fat or high-carb snacks. In fact, the high-carb snack did not delay dinner at all (20).

High-protein snacks that may suppress appetite include:

  • Peanuts and tree nuts (2122).
  • Greek yogurt (2324).

Snacks that are high in fiber may also promote fullness, compared to low-fiber snacks. Popcorn is a good example of a common high-fiber snack food.

Additionally, low-fat (air popped) popcorn is significantly more satiating compared to an equal amount of potato chips (25).

Bottom Line: Snack foods that are high in protein and/or fiber may reduce appetite, compared to other types of snack foods.

Can Snacking Reduce Body Weight?

A few randomized controlled trials have examined how different snack foods affect body weight.

One trial in women showed that snacking on dark chocolate daily reduced body weight and fat mass, compared to fruit-flavored licorice (26).

Other studies comparing a variety of different snack foods found no differences in daily food intake or changes in body weight (272829).

It appears that people may compensate for snacking by eating less food at meals. However, the calorie compensation is often only partial, and regular snacking may lead to weight gain over time (3031).

Additionally, not all snacks are equal. One study showed that eating nut-based snack bars for 3 months reduced body fat and abdominal fat in overweight people, compared to a cereal snack bar (32).

Observational studies have also provided mixed results. Some studies showed no significant links between snack foods and weight or body weight (7).

These findings are partially supported by other observational studies. One important exception is sugary soda, which was significantly linked to obesity (3334).

In general, it seems that snacking on calorie-dense, low-nutrient foods may promote weight gain. This especially applies to sugary soda.

That said, it is still unclear whether traditional snack foods reduce body weight, compared to not snacking. At this point, it seems unlikely.

Bottom Line: There is limited evidence that snack foods reduce body weight. In contrast, high-calorie snack foods may promote weight gain.

Summary and Real-Life Application

Taken together, studies investigating the effects of snack foods on body weight provide mixed results.

In general, high-calorie snack foods are believed to promote obesity, especially sugary soda. In contrast, people seem to partially compensate for consuming healthy snacks by eating less at the next meal.

Overall, there’s limited evidence that traditional snack foods lead to weight loss.

Asthma relief yet another reason to take Vitamin D

Vitamin D Pills Forming Letter D
Asthma is a chronic inflammatory disease that causes breathing difficulties. The underlying cause is incompletely understood.

A recent meta-analysis of randomized controlled trials examined the effects of vitamin D supplements on asthma symptoms. Here is a summary its conclusions.

 

Background

Asthma is a chronic inflammatory condition of the lung airways. It is characterized by attacks of breathlessness, chest tightness and wheezing.

Several observational studies have associated low circulating levels of vitamin D with an increased risk of asthma attacks (123).

These findings are partly supported by some meta-analyses of randomized controlled trials (456).

Article Reviewed

This was a meta-analysis of randomized controlled trials examining the evidence linking asthma with vitamin D.

Vitamin D for the management of asthma.

Study Design

This was a systematic review and meta-analysis of randomized controlled trials investigating the effects of vitamin D supplements on asthma symptoms.

The researchers searched for all relevant studies using several databases.

Only studies that met the inclusion criteria were selected:

  • The studies had to be double-blind, randomized controlled trials.
  • The participants had to be asthmatic adults or children.
  • The main outcomes were asthma symptoms and/or the risk of a sudden worsening of symptoms.
  • The studies had to last at least 3 months.

A total of nine trials met the inclusion criteria and were included in the primary analysis — seven in children and two in adults.

The studies included a total of 1,093 participants — 435 children and 658 adults — and their length ranged from 4–12 months. Most of the participants had mild to moderate asthma.

Bottom Line: This was a meta-analysis of nine randomized controlled trials examining the effects of vitamin D supplements on asthma symptoms in children and adults.

Finding 1: Vitamin D Reduced the Risk of Severe Asthma Attacks

The analysis showed that supplementing with vitamin D reduced the risk of a sudden worsening of symptoms (asthma attacks) requiring asthma medication (corticosteroids) via injection.

Specifically, the risk decreased by 37%, on average. It also caused a 61% reduction in the risk of having at least one asthma attack requiring a visit to an emergency department or hospital.

The authors concluded that this reduction in severe asthma attacks had significant clinical relevance.

Bottom Line: Taking vitamin D supplements reduced the risk of severe asthma attacks requiring corticosteroid injections, hospitalization or a visit to an emergency department.

Finding 2: Vitamin D Did Not Affect Day-To-Day Asthma Symptoms

In contrast to the protective effects of vitamin D against severe asthma attacks, the researchers concluded that it did not significantly affect Asthma Control Test (ACT) scores.

The ACT score is used to determine if asthma symptoms are well controlled and what level of treatment may be required.

In addition, supplementing with vitamin D did not affect the percent predicted forced expiratory volume in one second, which is a measure of lung function.

Bottom Line: Taking vitamin D supplements did not affect day-to-day asthma symptoms or lung function.

How Does Vitamin D Reduce the Risk of Asthma Attacks?

The analysis shows that taking vitamin D supplements may reduce the risk of asthma attacks.

The way vitamin D may improve asthma is not completely understood but may be explained in the following way:

  1. Supplementing with vitamin D leads to increased levels of calcifediol (hydroxyvitamin D), which is the main form of vitamin D in the blood.
  2. When needed, an enzyme known as CYP27B1 changes hydroxyvitamin D into calcitriol, the bioactive form of vitamin D.
  3. Calcitriol is produced by various body tissues, mainly the kidneys. However, inflammation (as in asthma) leads to increased levels of CYP27B1 in the tissues surrounding the airways, promoting the formation of calcitriol in the lungs.
  4. Calcitriol binds with the vitamin D receptor, which acts to reduce inflammation and stimulates the production of antimicrobial compounds (7891011).
  5. In this way, vitamin D could reduce the inflammation associated with asthma, potentially reducing the risk of severe asthma attacks.
  6. Asthma attacks are also frequently brought about by lung infections. The way vitamin D strengthens the antimicrobial defenses of the lungs may also play a role.

Bottom Line: Vitamin D may reduce the risk of asthma by reducing airway inflammation and strengthening the antimicrobial defenses of the lungs.

Limitations

This meta-analysis was conducted according to accepted standards and didn’t appear to have any flaws. However, caution should be taken when generalizing the results to certain groups.

First, the conclusion that vitamin D protects against severe asthma attacks was mostly based on studies in adults. As a result, it cannot be generalized to children.

Second, the researchers were unable to look into the effects of vitamin D supplements in subgroups, such as those with severe asthma or vitamin D deficiency.

Bottom Line: The findings cannot be generalized to children, and the effects of vitamin D supplements in those with severe asthma symptoms or good vitamin D status are unclear.

Summary and Real-Life Application

In short, this meta-analysis concludes that supplementing with vitamin D is likely to protect against severe asthma attacks. It also reduces the risk of having to visit an emergency department or stay in a hospital because of asthma.

Although vitamin D itself won’t cure asthma, supplementing with it seems to reduce the risk of severe asthma attacks in people with mild or moderate asthma.

However, studies in severely asthmatic people are lacking. Additionally, it is unclear if these benefits are confined to people with poor vitamin D status or a deficiency.

Alternate day fasting is effective weight loss plan


Following a standard weight loss diet is difficult for most people who too often depend on the fad weight loss pills like Garcinia Cambogia extract.

Recently different methods such as intermittent fasting are gaining popularity.

A randomized controlled trial compared the safety and effectiveness of alternate-day fasting to a traditional, calorie-reduced diet. Here is a detailed summary of its findings.

Background

When people diet, they eat less than they normally would.

Typically, an effective weight loss diet involves a 20–30% calorie deficit, relative to the amount of calories needed to maintain weight. It generally leads to a moderate 5–10% weight loss over a 6-month period (12).

However, sticking to a calorie-reduced diet for a long period is extremely difficult for most people (3).

For this reason, alternative strategies are growing in popularity. One such strategy is intermittent fasting, which involves eating little or nothing for specified periods and normally the rest of the time.

One common intermittent fasting approach is alternate-day fasting (ADF), which involves eating little or nothing every other day.

Like most other weight loss methods, ADF reduces the risk of heart disease and diabetes. It may also cause beneficial changes in appetite hormones (456).

Studies in overweight or obese adults indicate that ADF may cause 3–8% weight loss over a period of 2–12 weeks (78).

Yet, it’s still unclear whether ADF is an effective weight loss strategy. Until now, no studies have compared ADF to a traditional weight loss diet (9).

Article Reviewed

screen-shot-2016-10-26-at-10-41-04-pmThis was a randomized controlled trial comparing the effectiveness of alternate-day fasting to a standard weight loss diet.

A randomized pilot study comparing zero-calorie alternate-day fasting to daily caloric restriction in adults with obesity.

Study Design

This was a small, 2-month randomized controlled trial examining the safety and effectiveness of alternate-day fasting, compared to a traditional weight loss diet.

A total of 26 obese adults participated in the study. They were randomly assigned to one of two groups:

  • Alternate-day fasting (ADF): Participants fasted every other day. On non-fasting days, they could eat as much as they wanted. On fasting days, they were only allowed to consume water, calorie-free beverages and stocks or broths.
  • Traditional weight loss diet (TWD): Participants followed a calorie-restricted diet (a deficit of 400 calories per day) for two months.

In both groups, all food was provided by the study kitchen, and food intake was closely monitored. Additionally, the participants’ macronutrient intakes were standardized with 55% of calories from carbs, 15% from protein and 30% from fat.

At the start and end of the study, the researchers measured the following:

  • Body weight.
  • Body composition: Measured using dual-energy X-ray absorptiometry.
  • Blood lipids: Total cholesterol, triglycerides and HDL were measured in fasting blood samples.
  • Blood sugar control: Evaluated with a glucose tolerance test.
  • Resting metabolic rate: Assessed in the morning using standard indirect calorimetry.
  • Appetite hormones: Leptin and ghrelin were measured in fasting blood samples.
  • Brain-derived neurotropic factor (BDNF).

When the study was over, the participants received standard weight maintenance advice. The above measurements were repeated after a 6-month unsupervised follow-up.

Summary: This was a randomized controlled trial comparing the safety and effectiveness of alternate-day fasting to a traditional weight loss diet.

Finding 1: Alternate-Day Fasting and Standard Dieting Caused Similar Weight Loss

Alternate-day fasting (ADF) and the traditional weight loss diet (TWD) caused similar weight loss.

Specifically, those who fasted every other day lost 18.1 pounds (8.2 kg), on average, whereas those who dieted every day lost 15.7 pounds (7.1 kg), as shown in the chart below.

Weight Loss ADF TWD

Although the weight loss was slightly higher among those who fasted every other day, the difference was not statistically significant. However, the relative weight loss (percentage of body weight) was nearly significant.

Further studies with a greater number of participants and more statistical power are needed to determine whether this difference is real or just a chance occurrence.

Summary: Alternate-day fasting led to weight loss similar to that of a standard weight loss diet with a moderate calorie deficit.

Finding 2: Alternate-Day Fasting Led to a Greater Calorie Deficit

Participants who fasted every other day achieved a greater calorie deficit.

They consumed 376 fewer calories per day, on average, compared to those who were on the traditional weight loss diet.

The chart below shows the differences in calorie deficit between groups.

Calorie Deficit ADF TWD

This is a large reduction in calories that should lead to considerable weight loss over two months.

However, this extra calorie deficit didn’t seem to significantly affect weight loss, as shown in the previous section.

Possible explanations include the underreporting of food intake in the ADF group or a reduction in the number of calories burned.

Summary: Alternate-day fasting seemed to cause a greater calorie deficit, on average, compared to a traditional weight loss diet.

Finding 3: Alternative-Fasting Had Favorable Effects on Body Composition

After the intervention part of the study had ended, the researchers followed the participants for an additional six months.

During these six months, there were no significant changes in weight regain between groups.

However, when the researchers compared values from the start of the intervention, changes in percent fat mass (FM) and lean mass (LM) were significantly more favorable among those who fasted every other day.

These findings are presented in the chart below.

Change FM Trunk FM LM

These findings should be interpreted with caution since there were some between-group differences in body weight at the start of the study.

Summary: Alternate-day fasting appeared to beneficially affect body composition, compared to a traditional weight loss diet.

Finding 4: Resting Metabolic Rate Decreased in Both Groups

Both alternate-day fasting and traditional dieting caused a drop in the number of calories burned at rest (resting metabolic rate).

This effect is known as metabolic adaptation or starvation mode — the body’s response to a calorie deficit.

When the decrease in resting metabolic rate (RMR) was adjusted for fat mass and lean mass, the difference between groups became marginally significant. The findings are presented in the chart below.

Change In Resting Metabolic Rate

Summary: Both alternate-day fasting and a calorie-reduced diet caused a decrease in resting metabolic rate.

Finding 5: Alternate-Day Fasting Caused an Increase in BDNF

Previous studies suggest that fasting may improve mental performance, possibly due to changes in brain-derived neurotrophic factor (BDNF).

BDNF may also be involved in the regulation of energy balance (10111213).

In the current study, there were no differences in BDNF levels between groups.

However, at the end of the follow-up period, the researchers discovered that levels of BDNF had increased significantly among those in the ADF group, compared to the TWD group, as shown in the chart below.

Change In BDNF ADF TWD

These findings suggest that ADF may lead to long-term changes in the formation of BDNF, which might promote weight loss maintenance. This needs to be studied further.

Summary: Alternate-day fasting led to an increase in brain-derived neurotropic factor. The health relevance of this is unclear.

Finding 6: Effects of Alternate-Day Fasting on Appetite Hormones

Previous studies indicate that alternate-day fasting increases fullness after meals, as well as levels of the satiety hormone peptide YY (14).

In the present study, the researchers measured leptin (a satiety hormone) and ghrelin (the hunger hormone) at the start and end of the study. The findings are presented in the chart below.

Change Leptin Ghrelin ADF TWD

There were no significant differences in hormone changes between groups.

ADF also led to improvements in blood lipids. Once again, there were no significant between-group differences.

Summary: Alternate-day fasting and a traditional weight loss diet similarly affected the appetite hormones ghrelin and leptin.

Limitations

The main limitation of the study was its small size. The low statistical power may explain the lack of significant differences in some of the outcomes.

Second, physical activity levels weren’t monitored. This might have affected the results.

Third, the researchers didn’t know how many of the participants continued following the ADF or TWD during the follow-up period.

Finally, food intake was strictly controlled, and the findings may not be generalized to a free-living population.

Summary and Real-Life Application

In short, this study suggests that alternate-day fasting is safe and at least as effective as a moderate, calorie-reduced diet.

It did not raise the risk of weight regain during the first six months after the weight loss program finished.

Although weight loss wasn’t significantly different between groups, there were some signs that alternate-day fasting may be more beneficial than continuous dieting. These findings need to be confirmed by larger studies.

Health risks of excessive Red meat consumption


Numerous observational studies have associated a high intake of red meat with an increased risk of heart disease and cancer.

In contrast, a high intake of fruits and vegetables is linked with a reduced risk of heart disease and cancer.

A recent observational study investigated whether high intakes of fruits and vegetables would counterbalance the link between red meat intake and poor health. Here is a summary of its findings.

Background

Observational studies suggest that eating a lot of red meat may increase the risk of diabetes, heart disease, certain types of cancer and premature death (12345).

These associations are quite consistent across studies and populations. However, observational studies have a major weakness — they cannot prove causality.

As a result, scientists are still not entirely sure if high red meat intake itself is harmful or if other factors related to high red meat intake are responsible (16).

The unhealthy lifestyle habits sometimes associated with high red meat intake include:

  • Lower-quality diet (78).
  • Low consumption of fruits and vegetables (9).

Nevertheless, some scientists believe that certain components of red meat, especially in processed red meat or overcooked meat, may at least partially explain these associations.

Accordingly, some observational studies have linked processed meat with adverse health effects but not unprocessed, fresh red meat (51011).

Researchers have hypothesized that eating a lot of fruits and vegetables might partially offset the harmful effects of high red meat intake (9).

This hypothesis is supported by evidence indicating that high meat intake does not increase the risk of death when intake of fruits and vegetable is comparable to that of vegetarians (1213).

Article Reviewed

This observational study investigated the association of red meat intake with the risk of death from chronic disease at different levels of fruit and vegetable intake.

High red meat intake and all-cause cardiovascular and cancer mortality: is the risk modified by fruit and vegetable intake?

Study Design

This observational study examined whether high intakes of fruits and vegetables could offset the adverse health effects of red meat intake.

The researchers evaluated data from two large prospective studies, including a total of 74,645 Swedish men and women.

Food intake was evaluated using self-administered questionnaires asking how often people consumed fruits, vegetables, fresh meat or processed meat.

Fresh meats included fresh and minced pork, beef and veal, whereas processed meat included sausages, hot dogs, salami, ham, processed meat cuts, liver pate and blood sausage.

Bottom Line: This was an observational study investigating whether high intakes of fruits and vegetables can counterbalance the negative health effects of high red meat intake.

Finding 1: Red Meat Was Linked With an Increased Risk of Death

The study showed that eating a lot of red meat increased the risk of death from heart disease by 29% and the overall risk of death by 21%. However, it was not significantly associated with an increased risk of death from cancer.

The chart below shows the percent changes in the risk of death, compared to the lowest quintile of red meat consumption (less than 46 grams per day).

Interestingly, these associations were largely reduced when limiting the analyses to non-processed (fresh) red meat, suggesting that processed meat may be to blame.

Bottom Line: The study showed that a high intake of red meat, especially processed red meat, was significantly linked with an increased risk of death from heart disease or other causes.

Finding 2: Eating Fruits and Vegetables Didn’t Reduce the Health Risks of Red Meat Intake

The researchers discovered that red meat intake was associated with an increased risk of death, irrespective of how many fruits and vegetables people were eating.

The harmful effects of red meat were clearly dose dependent. The higher the intake, the more likely the participants were to die during the follow-up period.

Additionally, this association of red meat with death was independent of education status or unhealthy lifestyle habits, such as smoking or alcohol consumption.

The researchers also found that fruit and vegetable intake was not associated with total red meat intake or the intake of processed meat.

In other words, those who ate a lot of red meat didn’t necessarily eat less fruit and vegetables (FV), as shown in the chart below.

However, a high fruit and vegetable intake wasn’t associated with reduced risk of death from heart disease or other causes.

Bottom Line: High red meat intake was consistently associated with an increased risk of death at all levels of fruit and vegetable intake.

Limitations

The study’s main limitation was its observational design – it couldn’t demonstrate causality.

Second, food intake was self-assessed using food frequency questionnaires (FFQs), which are often inaccurate.

In addition, the questionnaires didn’t ask about lamb and game meat intake, which might have skewed the results.

Third, the study revealed no protective effects from fruit and vegetable consumption. This might explain why they didn’t counterbalance the increased risk associated with red meat intake.

Summary and Real-Life Application

In short, this observational study indicates that eating a lot of fruits and vegetables does not counterbalance the harmful effects of high red meat intake.

However, since the study had a few limitations, its findings should be taken with a grain of salt. The results need to be confirmed in future studies.

Try Magnesium to help lower blood sugar levels

Assortment Of Magnesium Rich FoodsSupplementing with magnesium has been popular in recent years and is claimed to improve health in many ways.

Not all of these claims are backed by science, but there is convincing evidence linking magnesium supplementation to a lower risk of type 2 diabetes.

A recent meta-analysis examined the effects of magnesium supplementation in diabetics or people at a high risk of developing type 2 diabetes. Here is a summary of its findings.

 

Background

Observational studies suggest that magnesium insufficiency or deficiency is linked with heart disease and several metabolic disorders, including hypertension, metabolic syndrome and type 2 diabetes (T2D) (123).

One large meta-analysis of observational studies including more than half a million participants showed that higher magnesium intake was associated with a lower risk of T2D (4).

Other studies have also shown that diabetics tend to have lower levels of magnesium, compared to healthy people (56).

However, the direction of causality is unclear. Diabetes might promote magnesium depletion or, alternatively, magnesium deficiency might increase the risk of T2D.

Randomized controlled trials support the second option. They show that supplementing with magnesium improves the symptoms of T2D, indicating that poor dietary intake of magnesium may, at least partly, contribute to its development (7).

But there is also some evidence suggesting that T2D may increase magnesium depletion, creating a vicious cycle (8).

Article Reviewed

This was a meta-analysis of randomized controlled trials examining the effects of magnesium supplementation on blood sugar control in people with type 2 diabetes (T2D) or those at a high risk of developing it.

Effect of magnesium supplementation on glucose metabolism in people with or at risk of diabetes: a systematic review and meta-analysis of double-blind randomized controlled trials.

Study Design

This was a systematic review and meta-analysis of randomized controlled trials examining the effects of magnesium supplementation on markers of blood sugar control and insulin sensitivity.

The researchers searched for relevant articles using five of the largest scientific databases.

The inclusion criteria were the following:

  • A double-blind, randomized controlled trial.
  • Participants were diabetic or at a high risk of developing T2D.
  • The studies examined oral magnesium supplementation.
  • Outcomes included markers of glucose metabolism or insulin sensitivity.

A total of 18 randomized controlled trials fulfilled all of the inclusion criteria — 12 studies included people with T2D and 6 included people at a high risk of diabetes.

Bottom Line: This was a meta-analysis of randomized controlled trials examining the association of magnesium supplementation with blood sugar control in diabetics or people at a high risk of developing type 2 diabetes.

Finding 1: Magnesium Reduced Fasting Blood Sugar Levels

The analysis showed that supplementing with magnesium significantly reduced fasting blood sugar levels in people with T2D or at a high risk of it, compared to a placebo.

Specifically, the standard mean difference was -0.4, which means that magnesium caused a moderate improvement (decrease) in blood sugar levels.

However, magnesium did not affect fasting blood sugar levels in people who didn’t have type 2 diabetes.

Additionally, levels of fasting insulin, insulin sensitivity (HOMA-IR) or HbA1c didn’t change significantly.

Bottom Line: Supplementing with magnesium reduced fasting blood sugar levels in people with type 2 diabetes.

Finding 2: Magnesium Reduced the Rise in Blood Sugar After Eating Sugar

An oral glucose tolerance test (OGTT) measures the changes in blood sugar after eating a dose of pure sugar (glucose). It is currently the gold standard for diagnosing diabetes.

Three of the included studies investigated the effects of magnesium on blood sugar levels during an OGTT in people at a high risk of developing diabetes.

Based on these studies, the researchers concluded that supplementing with magnesium significantly reduces blood sugar levels after eating sugar.

Specifically, the standard mean difference was -0.35, which is a moderate effect.

These findings were supported by one study that measured OGT in diabetics (9).

Bottom Line: Supplementing with magnesium significantly reduced the rise in blood sugar during an oral glucose tolerance test.

Finding 3: High Magnesium Levels Associated With Lower HbA1c Levels in Diabetics

Glycated hemoglobin (HbA1c) is a marker of the previous three-month average in blood sugar levels.

Analyses revealed that high magnesium levels correlated with lower levels of glycated hemoglobin (HbA1c) in people with T2D, supporting the overall findings of the meta-analysis.

However, supplementing with magnesium did not affect HbA1c levels, probably because changes in HbA1c are slow and many of the studies were short in duration.

Magnesium status was also associated with improved insulin sensitivity in people at a high risk of T2D, but no significant links were detected in diabetics.

Bottom Line: Observational studies showed that high magnesium levels were linked with lower HbA1c levels in diabetics.

How Does Magnesium Deficiency Impair Blood Sugar Control?

The meta-analysis strongly suggests that supplementing with magnesium benefits diabetics and those at a high risk of it.

There are several mechanisms by which magnesium insufficiency could impair blood sugar control.

  • Sustained magnesium deficiency appears to reduce blood sugar uptake (1011).
  • Low magnesium levels may impair insulin release from the beta-cells in the pancreas (1213).
  • Poor magnesium status might increase oxidative stress, possibly increasing insulin resistance (10).

Bottom Line: Magnesium deficiency could impair blood sugar control by reducing sugar uptake (insulin sensitivity), impairing insulin release and/or increasing oxidative stress.

Limitations

This meta-analysis seems to have been designed well, and it followed accepted guidelines.

Although the included trials were generally high-quality, they included few participants and were generally short in duration. Long-term trials are needed.

Finally, the included studies varied in their design. For example, the doses of magnesium, as well as its form, differed considerably across studies.

Bottom Line: The included studies were generally of short duration, and their designs varied.

Summary and Real-Life Application

The researchers concluded that supplementing with magnesium may improve blood sugar control in diabetics, as well as people at a high risk of developing diabetes.

If you are diabetic or at risk of developing diabetes, supplementing with magnesium may be a good idea. However, you can also get all the magnesium you need from whole foods.

Magnesium-rich foods include whole grains, nuts, seeds, beans, dark leafy greens and fish. It is also abundant in coffee, cocoa and dark chocolate.

Heart Attack risk cut by Omega 3 fats

Omega 3 Supplements And FoodsThe health benefits of long-chain omega-3 fatty acids — docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) – are well known.

One large trial in patients with heart disease showe
d that supplementing with 1 gram of omega-3 per day reduced their risk of death by 20%. However, not all studies agree (12).

Recently, a large randomized controlled t
rial examined whether supplementing with 4 grams of omega-3 would help repair some of the damage caused by a heart attack. Below is a detailed summary of its findings.

 

Article Reviewed

This study examined the benefits of high-dose omega-3 supplementation on heart recovery after a heart attack.

Effect of Omega-3 Acid Ethyl Esters on Left Ventricular Remodeling After Acute Myocardial Infarction. The OMEGA-REMODEL Randomized Clinical Trial.

Study Design

This randomized controlled trial investigated the effects of omega-3 fatty acids on changes in heart function and structure during the first 6 months after a heart attack (acute myocardial infarction).

A total of 358 participants were randomly assigned to one of two groups 14 to 28 days after they had a heart attack:

  • Omega-3: The participants received high-dose omega-3 supplements from fish oil (4 grams per day for 6 months). The supplement contained ethyl esters of EPA (465 mg) and DHA (375 mg).
  • Placebo: The control capsules contained corn oil, providing 600 mg of omega-6 linoleic acid.

During the study, all of the participants were also receiving standard medical therapy to treat heart disease.

At the start and end of the study, the researchers measured heart structure and function using cardiac magnetic resonance imaging. They also measured several markers of inflammation and cardiac fibrosis.

Bottom Line: This was a large randomized controlled trial investigating the effects of high-dose omega-3 supplementation on changes in heart structure and function after a heart attack.

Finding 1: Omega-3 Supplements Improved Heart Function

Left ventricular systolic volume index (LVSVI) is a marker of the heart’s ability to pump blood.

The researchers discovered that high-dose omega-3 supplementation reduced LVSVI by 5.8%, compared to a placebo. This is a beneficial change, indicating improved heart function.

The chart below shows the changes in LVSVI in both groups:

Change In LVSVI

There was a dose-response relationship between these benefits and increases in the omega-3 content of red blood cells (RBC).

Among those participants who achieved the highest increase in the omega-3 content of RBCs, the reduction in LVSVI was much higher at 13%.

Bottom Line: Supplementing with 4 grams of omega-3 for half a year after a heart attack significantly improved heart function, compared to a placebo.

Finding 2: Omega-3 Supplements Reduced Myocardial Fibrosis

Myocardial fibrosis (MF) is a condition characterized by the accumulation of scar tissue in the heart muscle. It reduces the heart’s ability to contract and pump blood.

Increased MF is often seen following a heart attack and increases the risk of heart failure.

The researchers assessed non-infarct myocardial fibrosis (NMF), which is myocardial fibrosis in undamaged areas of the heart.

The researchers were unable to measure NMF directly. Instead, they measured extracellular volume fraction, which is a marker of MF.

On average, the participants experienced a 5.6% improvement in NMF, compared to a placebo. The chart below shows the differences between groups:

Change In NMF

The researchers also measured ST2, a circulating marker of MF. Levels of ST2 are elevated when the heart muscle is dysfunctional or partially dead (3).

They discovered that high-dose omega-3 supplementation reduced ST2 by 7.9%, further confirming its benefits for patients with heart disease. These findings are consistent with previous studies (4).

Both groups also experienced a significant improvement in infarct size (areas of dead heart tissue), but the difference was not statistically significant between groups.

All of these benefits were associated with an increase in the omega-3 content of red blood cells.

Bottom Line: Supplementing with omega-3 decreased heart tissue scarring (myocardial fibrosis), reducing the risk of heart failure.

Finding 3: Omega-3 Supplements Decreased Inflammation

The study found that supplementing with omega-3 reduced circulating levels of myeloperoxidase by 8.1%.

Myeloperoxidase is an enzyme that has been used as a marker of inflammation in the heart (5).

The authors speculated that the anti-inflammatory effects of omega-3 fatty acids explain the health benefits seen in the current study.

These findings are consistent with previous studies in animals and humans (678).

Bottom Line: Omega-3 supplements also decreased inflammation, potentially explaining their benefits for heart function.

Limitations

This study didn’t have any major limitations.

However, a considerable proportion of the participants couldn’t return for a lab visit at the end of the study.

Additionally, the participants started supplementing with omega-3 two to four weeks after having a heart attack.

Changes in LVSVI and NMF were only modest compared to clinical care guidelines, but much greater benefits could have been achieved if the treatment had started earlier.

Finally, the omega-3 came from a prescription supplement with the brand name Lovaza, which was provided by the pharmaceutical company GlaxoSmithKline. It is unclear if regular omega-3 supplements are as effective.

Bottom Line: This study didn’t appear to have any major limitations. However, if the omega-3 treatment had started immediately after a heart attack, the participants might have achieved much greater benefits.

Summary and Real-Life Application

In short, this study showed that supplementing with 4 grams of omega-3 for 6 months helped repair some of the damage caused by a heart attack.

Many previous studies have confirmed the health benefits of omega-3 supplements, and most health authorities promote adequate dietary intake of omega-3 oils.

The present results strongly support the use of high-dose omega-3 supplements after a heart attack.

But even if you are healthy and fit, regularly eating fatty fish or supplementing with omega-3 might reduce your risk of developing chronic disease later in life.

How Coconut Oil and other MCT’s aid weight loss

How quickly you become hungry after eating not only depends on how much you ate, it also depends on what you ate.

Diet pills like Garcinia Cambogia can help, but its also important to know that some foods are more filling or satiating than others.

A recent study compared the effects of two types of fat — conjugated linoleic acid (CLA) and medium-chain triglycerides (MCTs) — on subsequent appetite and calorie intake.

Here is a detailed summary of its findings, as well as some background information.

Background

Fat is the most calorie-rich nutrient you can find, providing 9 kcal for each gram, exceeding protein and carbs by 5 kcal.

However, fat isn’t necessarily fattening. It all depends on how much you eat, the dietary context and the type of fat.

In fact, some types of fat seem to promote the loss of excess weight. This includes conjugated linoleic acid (CLA) and medium-chain triglycerides (MCTs).

Conjugated Linoleic Acid (CLA)

cla-in-dairyCLA is a type of fat found in the milk and meat of ruminant animals, such as sheep and cows.

Supplementing with CLA is believed to benefit those who wish to lose excess fat. This is supported by a few human trials. However, the effects are small, and the clinical relevance is unclear (1234).

One trial showed that CLA may reduce appetite, while other studies have detected no effects (567).

However, its effects on calorie intake in humans have not been investigated before.

Medium-chain Triglycerides (MCTs)

medium-chain-triglyceridesMCTs are a type of fat mainly found in palm oil, coconut oil, milk fat or supplements. They are more water-soluble and are quickly absorbed into the bloodstream after a meal.

Compared to long-chain triglycerides (LCT), MCTs may reduce appetite, calorie intake and promote weight loss (891011).

This is likely because MCTs are a more readily available calorie source than LCT (12).

However, not all studies agree. Some studies found that supplementing with MCTs did not affect appetite (1314).

Article Reviewed

This study tested the effects of conjugated linoleic acid (CLA) and medium-chain triglycerides (MCTs) on appetite and calorie intake.

Medium-chain triglycerides and conjugated linoleic acids in beverage form increase satiety and reduce food intake in humans.
screen-shot-2016-10-26-at-2-14-13-pm

Study Design

This was a randomized controlled trial examining the effects of different types of fat on appetite and calorie intake.

A total of 19 healthy men and women participated in the study. They were assigned to three test breakfasts on separate days in a random order.

All three breakfasts consisted of 250 ml of a Tesco red berries smoothie (123 kcal), providing 0.8 grams of protein and 29.8 grams of carbs (91% sugar).

Added to the smoothie were 193 kcal of fat, but the type of fat differed between the three breakfasts:

  • Conjugated linoleic acid (CLA): 5 grams of CLA and 16 grams of vegetable oil.
  • Medium-chain triglycerides (MCTs): 25 grams.
  • Control: 22 grams of vegetable oil (unspecified).

After breakfast the participants were told to request a sandwich buffet lunch when they felt hungry enough.

The researchers measured calorie intake at the sandwich lunch. Weighed food diaries were also used to assess food intake for the rest of the day.

They also measured the time between the breakfast and self-requested lunch and assessed appetite using visual analogue scale questionnaires.

Bottom Line: This was a randomized controlled trial comparing the effects of supplementing with MCTs and CLA at breakfast on calorie intake and appetite for the rest of the day.

Finding: CLA and MCTs Reduced Calorie Intake

Supplementing with conjugated linoleic acid (CLA) or medium-chain triglycerides (MCTs) for breakfast resulted in a similar calorie intake at the lunch buffet, compared to supplementing with vegetable oil.

However, calorie intake for the rest of the day (after lunch) was significantly reduced after the participants had supplemented with CLA or MCTs for breakfast, as shown in the chart below.

Calorie Intake CLA MCT Control

Supplementing with CLA for breakfast also delayed the time until the participants requested the lunch buffet. Yet, the researchers detected no significant differences in appetite ratings.

Bottom Line: Eating CLA or MCTs at breakfast reduced calorie intake by roughly 500 kcal for the rest of the day.

Limitations

3-question-marksThe study’s design doesn’t seem to have had any major flaws, but several limitations should be mentioned.

First, the lunch buffet didn’t have a fixed time. The participants asked for it when they felt hungry enough.

Although this probably didn’t change the study’s overall findings, it probably explains why the researchers didn’t detect any between-group differences in calorie intake at lunch.

Second, calorie intake after lunch was estimated using food diaries, which are often inaccurate. However, this is unlikely to have affected the main results.

Third, five participants reported adverse digestive symptoms after supplementing with MCTs. This discomfort might have reduced their appetite and calorie intake later in the day.

In comparison, only one participant reported digestive discomfort after supplementing with CLA, and there were no adverse symptoms after consuming the control breakfast.

Finally, the calorie content of the two test lipids did not match. The amount of CLA used was 5 grams, whereas the dose of MCTs was 25 grams. As a result, the study didn’t provide an equal comparison of CLA and MCTs.

Bottom Line: The study didn’t have any major limitations to its design. However, there are some limitations to how its results can be interpreted.

Summary and Real-Life Application

This study showed that supplementing with CLA or MCTs for breakfast significantly reduced calorie intake for the rest of the day, compared to vegetable oil.

The reduction in calorie intake amounted to approximately 500 kcal. This calorie reduction should result in considerable weight loss over time, but it is unclear to what extent these effects are sustained when CLA or MCTs are taken regularly.

Some previous studies have indicated that supplementing with MCTs or CLA may help people lose excess weight, although the relevance is still debated (415).

Sleep important for Weight and Fat Loss

Beautiful woman sleeping

Most people know that adequate sleep is one of the cornerstones of good health. But is poor sleep bad for your waistline?

It’s not as flashy as diet products like Garcinia Cambogia, but adequate sleep is important for weight loss.

A recent meta-analysis examined the association of sleep quality and overweight and obesity in young people. Here is a detailed summary of its findings.

 

Background

obese-man-with-doctorMany previous studies suggest that inadequate sleep makes people more likely to gain weight (12).

However, most of them have investigated sleep duration rather than quality (345).

As opposed to sleep duration, sleep quality is more about the personal experience of sleep, such as difficulties falling asleep or sleep satisfaction. Broken sleep is also an aspect of sleep quality (6).

Some observational studies indicate that light pollution at night might increase weight by disrupting sleep.

However, until now, no meta-analyses have examined the association of sleep quality and overweight or obesity.

Article Reviewed

This was a systematic review and meta-analysis on the association of sleep quality and overweight and obesity.

Sleep quality and obesity in young subjects: a meta-analysis.
screen-shot-2016-10-26-at-1-33-00-pm

Study Design

This was a systematic review and meta-analysis of observational studies.

Its purpose was to examine the association of sleep quality and overweight and obesity in young people and find out if the association is independent of sleep duration.

The researchers selected nine observational studies for the meta-analysis, including a total of 26,553 children, adolescents and young adults.

Most of the included studies had a cross-sectional design, meaning that they examined the association at one point in time. In other words, they didn’t investigate the effect of poor quality sleep on weight changes over time.

Studies were excluded if they didn’t include body mass index as an outcome or the participants had medical or psychological problems.

Additionally, studies were left out if they only focused on sleep duration or all of the participants were overweight or obese.

Poor sleep quality was defined as difficulties falling asleep and sleep disturbances (recurrent awakenings).

Some of the studies assessed sleep using the Pittsburgh Sleep Quality Index or the Children’s Sleep Habits Questionnaire, both of which evaluate sleep duration and quality.

Bottom Line: This was a systematic review and meta-analysis of studies examining the association of sleep quality and overweight or obesity.

Finding: Poor Sleep Quality Was Associated With Overweight and Obesity

bad-sleep
This meta-analysis suggests that both short sleep duration and poor sleep quality makes young people more likely to be overweight or obese.

The association of sleep quality and overweight or obesity seemed to be independent of sleep duration (78).

Most of the included studies found that inadequate sleep was significantly associated with overweight and obesity.

However, the studies that used non-validated research methods provided mixed results (7910).

Most of the included studies were cross-sectional, measuring associations at one point in time. In contrast, only two of the studies were longitudinal, measuring sleep quality and changes in weight over time.

The longitudinal studies found no significant links between sleep quality and overweight or obesity (911).

Bottom Line: The study suggests that poor sleep quality is associated with overweight and obesity in young people, independently of sleep duration.

How Could Low Sleep Quality Make People Fat?

Although this study didn’t prove that poor sleep quality may lead to fat gain, it seems plausible that it might.

The potential mechanisms are unclear, but scientists have a few ideas.

  • Disrupted body clock: The body’s timekeeping system regulates many aspects of metabolism. Disrupting this system by sleeping irregularly or poorly may increase weight gain. (1213).
  • Increased appetite: Irregular or low-quality sleep can disrupt the 24-hour fluctuations in appetite hormones, promoting increased calorie intake during the day and at night (14).
  • Food intake at night: Broken sleep or difficulties falling asleep may encourage night-time eating, leading to more weight gain.

Bottom Line: Several plausible ideas explain how poor sleep might promote weight gain. For example, low sleep quality may disrupt the body clock and encourage night-time snacking.

Limitations

This study had a few important limitations.

First, all of the included studies had an observational design, and all but three were cross-sectional. This means that they couldn’t prove causality and didn’t show that poor sleep was linked with weight gain over time.

It’s plausible that being overweight or obese may reduce sleep quality, rather than the other way around.

Second, only three studies measured sleep quality, using actigraphy. Additionally, most of the included studies used validated questionnaires, whereas three relied on parental or self-reporting.

Finally, most of the studies used body mass index (BMI) as an outcome. Four of the studies used self-reported height and weight for calculating BMI. BMI is an inaccurate measure of overweight, especially when relying on self-reports.

Bottom Line: The meta-analysis included observational studies, which cannot prove a causal relationship. Additionally, most of the studies relied on inaccurate measurements.

Summary and Real-Life Application

In short, this study indicates that poor sleep quality — broken sleep or difficulties falling asleep — are associated with excessive fat mass.

However, the evidence is weak, and the direction of causality is unclear. Obesity, overweight or related factors are plausibly responsible for poor sleep quality, at least in some cases.

Regardless, there is no doubt that getting high-quality sleep is important for maintaining a healthy mind and body.

Obese People’s Brains Respond Differently to Sugar

Many people believe that excessive sugar intake is one of the main reasons for the “obesity epidemic.”

This is not because sugar is high in calories. Instead, evidence suggests that sugar may increase cravings and promote higher overall calorie intake.

Recently, a team of researchers examined the effects of sugar — glucose and fructose — on brain activity in lean and obese adolescents. Here is a detailed summary of their findings.

Obese Woman Happily Eating Ice Cream Cone

Background

High intakes of sugar, especially sugar-sweetened beverages, have been associated with an increased risk of becoming overweight or obese.

The two most common forms of simple sugars (monosaccharides) in the diet are glucose and fructose. In foods, they often occur together or are combined in the form of sucrose (table sugar).

Some researchers have suggested that sugar may be addictive, similarly to some narcotic drugs, explaining its link to obesity (12).

Although several studies support this idea, strong evidence is still lacking.

Article Reviewed

This study examined the effects of glucose and fructose on blood flow in the brain of lean and obese adolescents.

Altered Brain Response to Drinking Glucose and Fructose in Obese Adolescents.

Study Design

This observational study investigated the effects of eating glucose and fructose on brain blood flow and appetite hormones in lean and obese adolescents.

A total 38 adolescents were recruited — 14 lean and 24 obese. They were 13–19 years old and apparently healthy.

On separate occasions after an overnight fast, the participants consumed 75 grams of glucose or 75 grams of fructose, dissolved in 300 ml of cherry-flavored water.

Afterwards, the researchers measured the following:

  • Brain blood flow: The researchers assessed cerebral blood flow (brain perfusion) in different brain regions, using pulsed arterial spin labeling (PASL) and functional MRI. The brain scans took an hour.
  • Glucose: Every 10 minutes the researchers took blood samples to measure blood sugar (glucose).
  • Fructose: Circulating levels of fructose were measured 20, 40 and 60 minutes after drinking the glucose and fructose beverages.
  • Appetite hormones: Ghrelin, insulin, leptin and adiponectin were also measured in blood samples.
  • Self-rated appetite: At the beginning and end of each session, the participants were asked to rate their feelings of hunger, satiety and fullness using a visual analog scale.

Bottom Line: This observational study examined the effects of eating glucose and fructose on brain activity in lean and obese adolescents.

Finding 1: Obese Adolescents’ Brains Responded Differently to Sugar

The researchers discovered that the brains of obese adolescents responded differently to sugar consumption, compared to those of lean adolescents.

In obese individuals, eating glucose or fructose reduced blood flow in the prefrontal cortex — a brain region involved with decision making and behavioral choices.

Glucose also increased blood flow in the hypothalamus — a region involved with appetite — whereas fructose increased blood flow in the ventral striatum — a brain region involved with food rewards, cravings and pleasure (3).

In contrast, when normal-weight individuals ate the same amount of glucose, blood flow increased in the prefrontal cortex, while remaining unchanged in the hypothalamus and ventral striatum.

Interpreting these findings, the authors speculated that sugar intake may reduce conscious control of sugar intake and increase brain activity involved with food reward processing. These effects might promote the overconsumption of sugar.

The results are supported by a previous study showing that obese adolescents had higher ratings of disinhibition (lack of restraint) and impulsivity (4).

Animal studies have also found that regular sugar intake may lead to binge drinking of sugar-sweetened beverages, sugar cravings and increased consumption of other foods when sugar is not available (1).

A previous study in lean adults showed that eating glucose reduced blood flow in the hypothalamus and ventral striatum, whereas fructose did not significantly affect blood flow (5).

Taken together, the results of the current and previous studies indicate that regular and excessive sugar intake might lead to sugar addiction in some people.

Bottom Line: In obese adolescents, sugar increased brain activity in regions involved with pleasure and cravings and reduced activity in regions involved with decision making.

Finding 2: Eating Sugar Increased Hunger in Obese Adolescents

Hunger ratings increased significantly after eating glucose and fructose in obese adolescents, whereas they remained unchanged in those who were lean.

However, ratings of fullness were higher among lean adolescents after drinking the fructose beverage.

These findings suggest that sugar intake may promote excessive calorie intake in obese individuals.

Bottom Line: Eating either glucose or fructose significantly increased self-rated feelings of hunger in obese adolescents. In contrast, glucose and fructose did not affect hunger ratings in lean participants.

Finding 3: Effects on Circulating Levels of Hormones and Sugar

Blood sugar (glucose) rose similarly in both obese and lean adolescents after consuming glucose. However, insulin levels were slightly higher in those who were obese.

A similar but insignificant increase in blood sugar was seen after eating the fructose.

Normally, glucose and fructose consumption reduces the levels of ghrelin — the hunger hormone. Compared to lean adolescents, this suppression of ghrelin levels was lower in obese adolescents.

These changes were associated with changes in blood flow in several brain regions — the hypothalamus, thalamus and hippocampus.

The authors speculated that changes in ghrelin and insulin may possibly contribute to the differences in brain activity. However, the role of insulin and ghrelin in obesity is still unclear.

Bottom Line: The hormones ghrelin and insulin might be involved with the glucose and fructose-related changes in brain activity. However, their exact role is still poorly understood.

Limitations

The main limitation of the current study is its assessment of brain activity. It measured neuronal activity indirectly by assessing brain blood flow (brain perfusion), a