Benefits of Intermittent Fasting for Weight Loss

fasting-monksThere are many different diets and plans that are popular for weight loss.

One that has recently been getting a lot of attention and I am personally using is called intermittent fasting

When you fast for short periods of time, it helps you to cut down the total calories you eat in a day.

And as an added bonus, it helps optimize the way some hormones work to signal your body for fat storage.

You can read about 6 Ways to do Intermittent Fasting, but the three most popular ones are:

  1. The 16/8 Method: Skip your breakfast throughout the week and eat only during an 8-hour feeding window, like from 12 noon to 8 pm.
  2. Eat-Stop-Eat: Do your fast once (or twice) every week for a 24-hour period. An example would be not eating from dinner one day until dinner the next day.
  3. The 5:2 Diet: Eat just 500-600 calories for two days of the week, but eat regularly the other 5 days.

With any of these methods, it is important that you don’t compensate by overeating during the non-fasting periods.

Adhering to sensible calorie consumption during the non-fasting periods will lead to a reduction in your total caloric intake, which will allow you to lose weight and fat around your belly (2, 3).

How Intermittent Fasting Influences Your Hormones for Fat Storage

fat storage hormones
Body fat is actually the result of how the body stores energy (calories).

When you haven’t had anything to eat for awhile, the body makes several hormonal adjustments so  the energy it’s already stored as fat is more  readily available.

Below are some of the things that happen to your metabolism when you are undergoing a fast:

  • Insulin: Insulin goes up when we digest food. When we fast, insulin in the body falls sharply. Fat burning is made easier with low levels of insulin.
  • Human growth hormone (HGH): Levels of growth hormone shoot up in the body during a period of fasting. This increase can be by as much as  5 x higher.  Growth hormone helps you to lose fat while also gaining muscle, along with other positive benefits (5, 6).Growth hormone  can aid fat loss and muscle gain, among other things (7, 8, 9).
  • Norepinephrine (noradrenaline): Your nervous system delivers norepinephrine to your fat cells. This makes them break down your body fat into free fatty acids that can then be burned for energy(10, 11).

Incredibly, despite what you may have heard  from proponents of the traditional 5-6 meal diet, short-term fasting appears to actually stimulate fat burning.

Of note, two studies have shown that fasting for about 48 hours or so boosts metabolism up to 14%(12, 13). However, fasting periods that are longer can suppress metabolism (14).

Short term fasting can be an excellent tool – it induces many changes including reduced insulin, more growth hormone and increased metabolism

Intermittent Fasting Helps You Reduce Your Calorie Intake


The primary reason that intermittent fasting assists with weight loss is that it helps you to consume fewer calories.

While calorie counting is normally not necessary with intermittent fasting, it is true that the weight loss is mostly due to the overall decrease in calorie intake.

Each of the protocols involves missing meals during the fasting periods. Unless you offset this deficit by eating a lot more during the eating periods, you will be taking in less calories.

According to this recent study, intermittent fasting can lead to an astounding amount of weight loss. In this 24 week long study, it was shown to reduce body weight up to 8% (2).

When looking at the actual rates of weight loss, people dropped about 0.55 pounds per week using intermittent fasting, but dropped up to 1.65 pounds per week using alternate-day fasting (2).

Participants lost up to 7% of their total waist circumference, which clearly shows that they lost fat around their belly.

These are fairly dramatic results that prove intermittent fasting can be very effective for weight loss.

More than just weight loss, the rewards of intermittent fasting are are also numerous positives for metabolic health such as lowered blood pressure.

These benefits may even include the prevention of chronic disease and a increase lifespan
(15, 16).

Bottom Line: Intermittent fasting is a simple way to restrict the amount of calories that many people find is easier to follow. Studies indicate that it can help you shed weight and belly fat.

How Intermittent Fasting can help you retain muscle mass

ripped girl
A nasty side effect of crash dieting is often a significant loss of muscle mass(17).

It is interesting that studies indicate less muscle loss from weight loss with Intermittent Fasting as opposed to other methods (18).

Another study showed a standard calorie restriction diet resulted in 25% of the weight loss to be muscle, vs only 10% of weight loss of those using intermittent fasting(18).

A third study had participants eat the same number of calories as usual, but have them all in a huge dinner and nothing else. Surprisingly, they lost body fat and increased muscle mass as well as many other positive changes in total health. (19).

Research indicates that Intermittent Fasting may result in less muscle loss for each pound of fat loss, as compared to non fasting diet plans

It is easier to eat healthy meals with Intermittent Fasting diet

healthy foods

For many people, the simplicity of meal planning is a huge benefit with Intermittent Fasting.

For example, with the 16/8 plan, you only have to plan 2 meals instead of 3 So there is less preparation, and you are more flexible when and where you have to be.

With the 5:2 plan, you only need to plan 500 calories for 2 days. the other 5 days you eat your normal diet, without having to plan for reduced calories.

No matter how well a diet works on paper, REAL people have to stick to it, and the simpler it is, the more likely you will be able to.

Intermittent Fasting is often much simpler than other diets, so is easier to stick to.

Final Thoughts

When it’s all said and done, intermittent fasting can be a helpful tool for weight loss.

In addition to making it easier to lose pounds, it often results in less loss of muscle mass and other improvements in body chemistry.

Its not for everyone, but many people are finding it beneficial. You can read more about Health Benefits of Intermittent Fasting here.


the 5-2 diet guide

Hungry Woman With a Can of FoodIntermittent fasting is an eating pattern that involves regular fasting.

The 5:2 diet, also known as The Fast Diet, is currently the most popular intermittent fasting diet.

It was popularized by British doctor and journalist Michael Mosley.

It’s called the 5:2 diet because five days of the week are normal eating days, while the other two restrict calories to 500–600 per day.

This diet is actually more of an eating pattern than a diet. There are no requirements about which foods to eat, but rather when you should eat them.

Many people find this way of eating to be easier to stick to than a traditional calorie-restricted diet (1).

This article explains everything you need to know about the 5:2 diet.

How to Do the 5:2 Diet

The 5:2 diet is actually very simple to explain.

For five days a week, you eat normally and don’t have to think about restricting calories.

Then, on the other two days, you reduce your calorie intake to a quarter of your daily needs. This is about 500 calories per day for women, and 600 for men.

You can choose whichever two days of the week you prefer, as long as there is at least 1 non-fasting day in between.

A common way of planning the week is to fast on Mondays and Thursdays, with 2 or 3 small meals, then eating normally for the rest of the week.

It’s important to emphasize that eating “normally” does not mean you can eat literally anything. If you binge on junk food, then you probably won’t lose any weight, and may even gain weight.

You should eat the same amount of food as if you hadn’t been fasting at all.

Bottom Line: The 5:2 diet involves eating normally for five days a week, then restricting your calorie intake to 500–600 calories on the other two days.

Health Benefits of Intermittent Fasting

Apple And Calculator

There are very few studies that test the 5:2 diet specifically.

However, there are plenty of studies on intermittent fasting as a whole, which show impressive health benefits (2, 3).

One important benefit is that intermittent fasting seems to be easier to follow than continuous calorie restriction, at least for some people (4, 5).

Many studies have shown that different types of intermittent fasting may significantly reduce insulin levels (2, 6, 7).

One study showed that the 5:2 diet caused weight loss similar to regular calorie restriction. Additionally, the diet was very effective at reducing insulin levels and improving insulin sensitivity (8).

Several studies have looked into the health effects of modified alternate day fasting, which is very similar to the 5:2 diet (ultimately, it’s a 4:3 diet) (9).

The 4:3 diet may help reduce insulin resistance, asthma, seasonal allergies, heart arrhythmias, menopausal hot flashes and more (10, 11).

One randomized controlled trial in both normal weight and overweight individuals showed major improvements in the group doing 4:3 fasting, compared to the control group that ate normally (12).

After 12 weeks, the fasting group had:

  • Reduced body weight by more than 5 kg.
  • Reduced fat mass by 3.5 kg, with no change in muscle mass.
  • Reduced blood levels of triglycerides by 20%.
  • Increased LDL particle size (which is a good thing).
  • Reduced levels of CRP, an important marker of inflammation in the body.
  • Decreased levels of leptin by up to 40%.

Bottom Line: The 5:2 diet may have several impressive health benefits. These include weight loss, reduced insulin resistance and decreased inflammation. Blood lipids may also be improved.

The 5:2 Diet for Weight Loss

Weight Scale

If you need to lose weight, the 5:2 diet can be very effective when done right.

This is mainly because the 5:2 eating pattern helps you consume fewer calories.

Therefore, it is very important not to compensate for the fasting days by eating much more on the non-fasting days. Intermittent fasting does not cause more weight loss than regular calorie restriction if total calories are matched (13, 14).

That being said, fasting protocols similar to the 5:2 diet have shown a lot of promise in studies on weight loss:

  • A recent review found that modified alternate day fasting caused weight loss of 3–8% over the course of 3–24 weeks (15).
  • In the same study, participants lost 4–7% of their waist circumference, meaning that they lost a lot of harmful belly fat.
  • Intermittent fasting causes a much smaller reduction in muscle mass than weight loss with conventional calorie restriction (15, 16).

Intermittent fasting is even more effective when combined with exercise, such as endurance or strength training (17).

Bottom Line: The 5:2 diet should be very effective for weight loss, if done correctly. It may help reduce belly fat, as well as help maintain muscle mass during weight loss.

How to Eat on Fasting Days

There is no rule as to what or when you must eat on the fasting days.

Overweight Woman Eating Salad

Some people function best by beginning the day with a small breakfast, while others find it best to start eating as late as possible.

Generally, there are two meal patterns that people use:

  1. Three small meals: Usually breakfast, lunch and dinner.
  2. Two slightly bigger meals: Only lunch and dinner.

Since calorie intake is limited — 500 for women and 600 for men — it makes sense to use your calorie budget wisely.

Try to focus on nutritious, high-fiber, high-protein foods that will make you feel full without consuming too many calories.

Soups are a great option on fast days. Studies have shown that they may make you feel more full than the same ingredients in original form, or foods with the same calorie content (18, 19).

Here are a few examples of foods that may be suitable for fast days:

  • A generous portion of vegetables.
  • Natural yogurt with berries.
  • Boiled or baked eggs.
  • Grilled fish or lean meat.
  • Cauliflower rice.
  • Soups (for example miso, tomato, cauliflower or vegetable).
  • Low-calorie cup soups.
  • Black coffee.
  • Tea.
  • Still or sparkling water.

There is no specific, correct way to eat on fasting days. You have to experiment and figure out what works best for you.

Delicious Low-Calorie Meals

There are plenty of websites with delicious meal plans and recipes for the 5:2 diet.

  • Check out this site for plenty of low-calorie meal ideas.
  • This site offers ideas for 10 fasting days that are worth checking out.
  • Here are 27 meal plans for 500-calorie fast days.
  • You can find all kinds of information and recipes on the chat forum of the official Fast Diet website.
  • There are also several books and cookbooks available for the 5:2 diet on Amazon, including the original best-selling The Fast Diet book.

Bottom Line: There are many meal plans and recipes available on the internet for 500–600 calorie fast days. Sticking to nutritious, high-fiber and high-protein foods is a good idea.

What to Do If You Feel Unwell or Uncontrollably Hungry

During the first few fast days, you can expect to have episodes of overwhelming hunger. It is also normal to feel a little weaker or slower than usual.

Beginner Fasting Woman Biting Plate

However, you’ll be surprised about how quickly the hunger fades, especially if you try to keep busy with work or other errands.

Additionally, most people find that the fast days become easier after the first few fasts.

If you are not used to fasting, it may be a good idea to keep a small snack handy during your first few fasts, just in case you feel faint or ill.

But if you repeatedly find yourself feeling ill or faint during fast days, then have something to eat and talk with your doctor about whether you should continue.

Intermittent fasting is not for everyone, and some people are unable to tolerate it.

Bottom Line: It is normal to be hungry or feel a little weaker during the first few fasts. If you repeatedly feel faint or ill, then you should probably stop the diet.

Who Should Avoid the 5:2 Diet, or Intermittent Fasting Overall?

Empty Plate

Although intermittent fasting is very safe for healthy, well-nourished people, it does not suit everyone.

Some people should avoid dietary restrictions and fasting completely. These include:

  • Individuals with a history of eating disorders.
  • Individuals sensitive to drops in blood sugar levels.
  • Pregnant women, nursing mothers, teenagers, children and individuals with type 1 diabetes.
  • People who are malnourished, underweight or have known nutrient deficiencies.
  • Women who are trying to conceive or have issues with fertility.

Furthermore, intermittent fasting may not be as beneficial for some women as it is for men (20, 21).

Some women have reported that their menstrual period stopped while they were following this type of eating pattern. However, things went back to normal when they returned to a regular diet.

Women should therefore be careful when starting any form of intermittent fasting, and stop doing it immediately if any adverse effects occur.

Take Home Message

The 5:2 diet is an easy, effective way to lose weight and improve metabolic health.

Many people find it much easier to stick to than conventional calorie restriction.

If you’re looking to lose weight or improve your health, the 5:2 diet is definitely something to consider.