High-Fat Diet Doesn’t Cause Obesity
I wrote the other day about the less-than-optimal control animals and humans used in fasting and calorie-restriction studies. Partly this is due to the bad food that most people eat, as well as the substandard lab food that rats and mice eat. A similar problem exists in other diet experiments on lab animals. Here I’ll show that a high-fat diet doesn’t cause obesity – in lab animals anyway.
High-fat lab diets
If you read much of the scientific literature, you’ll come across lots of studies using lab rats and mice that were fed “high-fat” diets. Usually they produce ghastly results, like obesity, diabetes, cancer, cognitive deficits, and so on. Then the mainstream media trumpets these as meaning that you are going to get sick and die if you eat a high-fat diet.
Just to pull one more or less at random, “High-Fat Diet Disrupts Behavioral and Molecular Circadian Rhythms in Mice“. Control mice ate the Harlan Teklad 7012 diet of standard lab chow. It’s 25% protein, 17% fat, and 58% carbohydrate. Importantly, it contains no sugar and has high-quality, natural ingredients.
The high-fat group ate Research Diet 12451. Here are the ingredients:
This diet is 35% carbohydrate, 20% protein, and 45% fat. It contains sucrose – table sugar – as 17% of calories, as well as soybean oil, maltodextrin, and casein.
High fat? It’s more like dessert for rodents.
That amount of sugar is comparable to what the typical obese and heart-disease-prone American eats. Soybean oil has a high omega-6 content. Maltodextrin is a simple carbohydrate that turns to maltose and then glucose when absorbed, spiking blood sugar and insulin. Casein supplies all the protein, whereas the standard lab chow has no animal protein.
Yes, of course animals eating this garbage get sick.
Healthy high-fat diets
In contrast, look at another paper: A high-fat, ketogenic diet induces a unique metabolic state in mice. The animals on the ketogenic diet had lower body weight, lower glucose and insulin, and higher AMPK activity, a pro-longevity mechanism. When animals were switched to this diet, they lost weight. All very healthy, yet it was a high-fat diet, with 95% fat, 5% protein, and 0% carbohydrate. A very high-fat diet.
One of the experimental arms in this experiment was on the Research Diet 12451, as illustrated above. They got fat and sick.
Conclusion: Don’t believe everything you read
The animals on the “high-fat” diet in the first study were in reality eating a high-sugar, moderate-fat diet. Very misleading, if you ask me.
The animals in the second study ate a very high fat, no carb and sugar diet, and were healthy.
So next time you read about a high-fat diet making animals sick, diabetic, obese, or whatever, you can’t take it at face value.
Are carbohydrates needed to build muscle?
Lots of bodybuilders, most of them I would say, emphasize the need for a substantial amount of dietary carbohydrates to build muscle. The argument takes one or both of two forms; 1) that you need carbs to perform more intense exercise in the gym; and 2) carbs are needed to raise insulin and stimulate muscle growth. I’ve never found the arguments all that compelling, but then I’m just an average gym rat, not a bodybuilder extraordinaire. So how much truth is there in these statements?
First, as for intensity of workouts. A study was recently published in the Journal of the International Society of Sports Nutrition – which looked at elite level gymnasts. After 30 days on a ketogenic diet, i.e one with a very low carbohydrate content, probably under 50 grams a day, the athletes’ strength and power had not diminished. However, even these elite athletes, who one would presume were already in terrific shape, lost about 2 kg of fat, with a “non-significant” increase in muscle. This shows that if anything, at least for gymnasts, who require a high level of strength, the ketogenic diet was better than their regular diets. The authors conclude:
Despite concerns of coaches and doctors about the possible detrimental effects of low carbohydrate diets on athletic performance and the well known importance of carbohydrates there are no data about VLCKD and strength performance. The undeniable and sudden effect of VLCKD on fat loss may be useful for those athletes who compete in sports based on weight class. We have demonstrated that using VLCKD for a relatively short time period (i.e. 30 days) can decrease body weight and body fat without negative effects on strength performance in high level athletes.
Assuming that the same holds for bodybuilders, let’s move on to muscle hypertrophy. Another recent study found that carbohydrate does not augment exercise-induced protein accretion versus protein alone. In this study there were two conditions: young men performed resistance training followed by ingestion of either 25 grams of whey protein, or 25 grams of whey plus 50 grams of carbohydrate (maltodextrin). Despite the fact that the extra carbohydrate raised blood glucose levels 17.5 times higher and insulin levels 5 times higher (that is, area under the curve) than protein alone, no difference was found in either muscle protein synthesis or muscle protein breakdown.
So as long as you get adequate protein, you’ve maximized the amount of hypertrophy you can get out of resistance training. Protein raises insulin, which is required for hypertrophy, but raising insulin further does nothing.
Finally there’s an interesting new study, one the co-authors of which is Jeff Volek, who’s done so much great work in this area. The effects of ketogenic dieting on skeletal muscle and fat mass. One reason why it’s interesting is that the men in the study were already resistance-trained. Normally in studies like this they like to use newbies, as you see greater results in them; if already trained subjects are used, and there’s a difference between groups, then you know it really worked well.
Twenty-six college aged resistance trained men volunteered to participate in this study and were divided into VLCKD (5 % CHO, 75 % Fat, 20 % Pro) or a traditional western diet (55 % CHO, 25 % fat, 20 % pro). All subjects participated in a periodized resistance-training program three times per week….
Results: the ketogenic diet group gained 4.3 kg lean mass (muscle) compared to only 2.2 kg for the traditional diet group; the ketogenic group lost 2.2 kg of fat, compared to 1.5 kg in the traditional group.
I’d say this last study puts to rest any argument for lots of carbohydrates in weightlifting. The very low carbohydrate ketogenic diet was superior to a diet with 55% carbohydrate. Note that protein percent was the same for both groups.
Finally, there’s a very good book I recommend by the above-mentioned Jeff Volek and co-author Stephen Phinney, The Art and Science of Low Carbohydrate Performance.
So, no, carbohydrates are not needed to build muscle, and in fact muscle building might be even better without them.
Low-Carbohydrate Diet Beats Others for Weight Loss
Weight loss and the myth of saturated fat
What’s the best diet for weight loss? Much controversy swirls around this question because although diets like the low-carb Atkins diet have had great success, we don’t know whether they’re more effective, and besides we’ve been told for years that too much saturated fat in the diet may be bad for our health.
The “fact” that saturated fat may cause heart disease and be bad for our health generally has finally, and I believe definitively, been shown to be a myth. A meta-analysis from a few years ago, one of whose co-authors was Dr. Ronald Krauss, than whom it would be impossible to be more mainstream, showed that “there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD [coronary heart disease] or CVD [cardiovascular disease].” The myth of dietary fat and health risks has been expounded upon at length in the recent book by Nina Teicholz, The Big Fat Surprise, which I highly recommend.
As the myth of saturated fat has been debunked, we’re left with which diets are better for weight loss. One factor in that analysis is compliance, that is, to what extent dieters will stay on a diet. In compliance, there are basically two things to consider: 1) whether the food taste good; and 2) whether hunger can be kept under control.
Diets must control hunger
Food doesn’t just supply us with nutrients; it’s pleasant and the occasion for social interaction, and a diet depriving people of these will generally make them unhappy and unwilling to continue.
And if dieters are hungry, they are much more likely to break their diets and revert to their old, weight-gaining ways.
Low-fat diets, the kind prescribed over the past few decades, generally deprive dieters of foods that humans find naturally satisfying and that taste good, fatty foods like steak and all kinds of meats, butter, cream, cheese, eggs, even olive oil. Many or most people find that they feel deprived on such a diet – I would anyway.
On the other hand, low-carbohydrate diets deprive dieters of or severely limit sugar, bread, rolls, pasta, tortillas, candy, pastries, and any number of other things. However, on a calorically restricted low-fat diet, you can’t really eat your fill of these foods either.
So, as far as taste goes, a low-carbohydrate diet would seem to offer a better choice, being able to eat one’s fill of “main meal” type, satisfying foods, while limiting anything made with flour or sugar. Low-fat diets, if calorically restricted, limit these foods anyway.
What about hunger? Most people report less hunger on a low-carbohydrate diet, so they’re more likely to stay on it. But the kicker is that most low-carbohydrate diets do not restrict calories, while low-fat or conventional diets do. So even if low-carbohydrate, high-fat foods didn’t satisfy hunger more, the fact that one can just eat more of them would seem to make up for it. But all the evidence points to low-carb, high-fat foods as better able to eliminate hunger – in fact, that’s part of the mechanism that makes them work.
A head-to-head comparison of low-carbohydrate, low-fat, and Mediterranean diets
A study from a few years ago directly compared three different diets for weight loss: Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet. (New England Journal of Medicine.)
The low-fat diet was calorically restricted, with a target 1800 calories a day for men, 1500 for women. (Editorial comment: I’d be hungry on that amount of calories.) It was 30% of calories from fat, and “participants were counseled to consume low-fat grains, vegetables, fruits, and legumes and to limit their consumption of additional fats, sweets, and high-fat snacks”. (Editorial comment: even on this diet, sweets are limited.)
The Mediterranean diet’s target calorie intake was the same as for the low-fat, but with a goal of 35% calories from fat, “the main sources of added fat were 30 to 45 g of olive oil and a handful of nuts (five to seven nuts, that’s it).
The low-carbohydrate diet was not restricted in calories; it was all you can eat. (Now we’re talking.) It provided “20 g of carbohydrates per day for the 2-month induction phase…, with a gradual increase to a maximum of 120 g per day to maintain the weight loss. The intakes of total calories, protein, and fat were not limited. However, the participants were counseled to choose vegetarian sources of fat and protein and to avoid trans fat. The diet was based on the Atkins diet.” Unfortunately, we see the fear of saturated fat loom here, with “vegetarian sources of fat and protein”. At the beginning, the diet amounts to a ketogenic diet; it’s unclear why they felt the need to increase carbohydrates from the original to 120 grams. Possibly they think better compliance would result.
The study lasted for 2 years; all participants were either overweight (BMI ≥27), or with diabetes or coronary heart disease.
So, what happened? Drum roll, please…
Low-carbohydrate diet resulted in more weight loss
For participants who completed the entire 24-month program, weight loss was 3.3 kg (7.3 lbs.) on low-fat, 4.6 kg (10.1 lbs.) on the Mediterranean diet, and 5.5 kg (12.1 lbs.) on the low-carbohydrate diet. Low-carb was the clear winner.
Note from the above graph that with all diets, most weight loss occurred in the first 6 months, with either a plateau (Mediterranean) or a gradual weight regain. This pattern is often seen in diet studies and, no doubt, in real-world dieters.
The reasons for that are at least two or three. One is that dieters lose their initial enthusiasm and start to cheat. Another is a decrease in metabolism that follows weight loss; although this occurs with all weight loss, the low-carbohydrate diet appears to have a better record of maintaining metabolism, one reason being that it’s not calorically restricted. Finally, the low-carb diet had “cheating” built into it, with a beginning carbohydrate allocation of 20 grams a day, but rising to 120 grams a day later. That alone could easily account for weight regain.
The low-carbohydrate diet reduced disease risk more
The researchers wanted to know how each of these diets affected heart disease risk, and thus looked at lipid profiles. Results below.
We know that in lipid profiles, triglycerides (lower is better), HDL cholesterol (higher is better), and the ratio between the two have the most significance for heart disease risk. The low-carbohydrate diet trounced the others in this category.
Fasting glucose (chart not shown) remained about the same for all groups, although in diabetics, the Mediterranean diet group showed the greatest improvement.
Also in non-diabetics, the low-carbohydrate group showed the greatest decrease in fasting insulin levels. Since insulin is a pro-growth, anabolic hormone, and is implicated in aging, this gives further backing to the fact that a low-carbohydrate diet is an anti-aging diet. Of great interest, the level of C-reactive protein, which is a measure of inflammation, dropped the most on the low-carb diet. Again, since increasing inflammation is associated with aging, the low-carb diet can potentially slow the aging process.
The results show that the low-carbohydrate diet was the clear winner for weight loss. (Diabetics had somewhat better results with the Mediterranean diet, although not for weight loss.)
The better results on low-carb were likely due to two things, in my opinion. One is that insulin levels dropped. Insulin helps drive fat into cells, and lower insulin levels allow fat cells to release fat to be burned. The other reason is probably better compliance. This low-carbohydrate diet was unrestricted in calories, i.e. all-you-can-eat, therefore the participants on this diet were unlikely to get hungry and grab the nearest food available. The participants on the other, calorically restricted diets may have been much more likely to get hungry and cheat.
If weight loss is your goal, the choice seems clear enough. The addition of weight training and adequate protein intake to a low-carb diet will make the retention and even gaining of muscle possible, even while losing fat. (Annals of Nutrition and Metabolism.)
A couple of books that I like that thoroughly explain the low-carbohydrate diet, both by the same authors, Jeff Volek and Stephen Phinney, are The Art and Science of Low Carbohydrate Living, and for athletes, The Art and Science of Low Carbohydrate Performance.
Why a Low-Carb Diet Is Best for Weight Loss
If you want to lose weight, you have a number of choices. The most popular is to cut calories and eat a low-fat diet. A way that’s becoming more popular, because it works much better, is to cut carbohydrates. Here we’ll take a look at scientific proof that a low-carb diet is best for weight loss.
No calorie counting
The biggest impediment to losing weight on a low-calorie diet is hunger. If you voluntarily reduce calories while eating the same foods, you get hungry, as is to be expected. Your body defends its weight, i.e. it has a set point, and makes you hungry if your weight moves away from the set point.
On a low-carbohydrate diet, you merely cut the amount of carbohydrates in the diet, and in most studies looking at low-carb diets, the dieters ate as much as they wanted. Only carbohydrates were restricted. Cutting carbohydrates lowers levels of the hormone insulin, which signals the body to store fat, and which is responsible for setting the body weight set point. The result is nearly effortless weight loss.
In the first study we’ll look at, a group of obese women were randomized to either a low-fat, low-calorie diet, or a low-carbohydrate diet that was not restricted in calories, and followed for 6 months. Weight loss result in the chart below.
The low-carb group ate 20 g of carbohydrate daily, but were allowed to increase this to 40 to 60 g after 2 weeks, so long as they remained in ketosis as shown by urinary testing. The low-fat group was restricted in calories by 30% and ate about 55% of their calories as carbohydrates.
Despite the fact that the low-carb group could eat as much as they wanted, they spontaneously reduced their calorie intake to about the same as the low-fat group. That shows the power of low-carb in reducing hunger and changing the body’s weight set point. And they still lost more weight, an average of 7.6 kg, than the low-fat group, at an average of 4.2 kg.
You can even eat more calories and still lose weight
The second study concerns weight loss in obese teenagers. A group of adolescents, average age 14, were assigned to either a low-carb diet or a low-fat diet.
The low-carb group was instructed to keep carbohydrates at less than 20 g a day for the first 2 weeks, but increasing to 40 g a day in weeks 3 through 12. They could eat as musch as they wanted.
The low-fat group was instructed to keep fat at <40 g a day. They also could eat as much as they wanted.
Here are the results.
The low-carb teenagers averaged 9.9 kg of weight loss, compared to 4.9 kg in the low fat group. (That’s 22 pounds vs 11 pounds.) That was despite the fact that the low-carb group ate over 1800 calories a day, while the low-fat group ate 1100 calories a day. That’s the power of lowering carbohydrate intake. Also it’s guaranteed that the low-carb group was less hungry.
You don’t even need to reduce carbohydrates much
The third study compared a low-carbohydrate to a low-fat diet in severe obesity. These people had a high prevalence diabetes or metabolic syndrome.
The low-carbohydrate group was instructed to keep carbs at <30 g a day. However, they didn’t. They could eat as much as they wanted.
The low-fat group was instructed to keep fat at <30% of calories, and to reduce their calorie intake by 30%.
The low-carb group lost 5.8 kg after 6 months, the low-fat group 1.9 kg. (13 pounds vs 4 pounds.) The low-carb group spontaneously reduced their calorie intake, so that the 2 groups ate about the same number of calories, again showing the power of reducing hunger and body weight set point.
Notably, the low-carb group wasn’t very compliant, and they only reduced their carb intake to 37% of calories at 6 months, vs 51% for the low-fat group. Yet they still lost more weight.
Low-carb vs low fat and Mediterranean diets
The fourth study was a three-way comparison between a low-carb, low-fat, and Mediterranean diets. The low-fat and Mediterranean diets were restricted in calories, with limits of 1500 calories daily for women, and 1800 for men.
The low-carb dieters could eat as much as they wanted, so long as they restricted carbohydrates to 20 grams daily initially, but increasing to a maximum of 120 grams.
Here’s what happened:
Once again, low-carb is a clear winner. Low-fat lost 2.9 kg, Mediterranean 4.4 kg, and low-carb 4.7 kg. The low-carb group still ate a whopping 40% of calories as carbohydrates, although that was down from 51% at baseline, representing a drop of 120 grams of carbs daily.
Noteworthy is the increase in weight after the first few months of weight loss, which was greatest in the low-carb group. That group actually increased its carb intake slightly. Another explanation might be a lower metabolic rate and/or less exercise. the low-carb group did decrease the amount of exercise between 6 and 24 months; the low-fat group increased exercise.
Reviews of low-carb diets
We’ve seen above that several studies have found that low-carbohydrate diets are superior for weight loss. have I cherry-picked the studies? Nope.
Several meta-analyses (reviews of studies) have found that low-carb diets beat calorie-restricted low-fat diets.
This trial-level meta-analysis of randomized controlled trials comparing LoCHO diets with LoFAT diets in strictly adherent populations demonstrates that each diet was associated with significant weight loss and reduction in predicted risk of ASCVD events. However, LoCHO diet was associated with modest but significantly greater improvements in weight loss and predicted ASCVD risk in studies from 8 weeks to 24 months in duration. These results suggest that future evaluations of dietary guidelines should consider low carbohydrate diets as effective and safe intervention for weight management in the overweight and obese, although long-term effects require further investigation.
Compared with participants on LF diets, participants on LC diets experienced a greater reduction in body weight.
What to eat on a low-carb diet
Low-carb diets vary in the degree of carbohydrate restriction. One scheme that I used in my book Stop the Clock was the following:
- moderately low-carb: <130 grams of carbohydrate daily
- low-carb: 50 to <130 grams daily
- very low-carb ketogenic: <50 grams daily.
As we saw in this article, virtually any degree of carbohydrate restriction is beneficial. But, the more you restrict carbs, the better your weight loss is likely to be.
Timothy Noakes, M.D., a noted advocate of low-carb diets, recently published an article, Evidence that supports the prescription of low-carbohydrate high-fat diets: a narrative review. In it, he listed the following foods as being “green-lighted” for a low-carbohydrate diet:
This list is meant for people who are insulin-resistant. If trying to lose weight, it would be a good idea to go easy on the added oils and nuts.
You should omit the following foods entirely:
- anything made with flour: bread, pasta, tortillas, pastries
- anything with added sugar: soft drinks, fruit juice, candy, cookies
- starch: potatoes, sweet potatoes
Did I miss anything? It’s easy, just eat plenty of meat, eggs, vegetables, cheese. Don’t go hungry.
For what it’s worth, I eat this way all the time. Most days my carb intake is probably 20 to 60 grams, some days rising to 100.