Does Intermittent Fast Work For Gaining Or Losing Muscle?

What is Intermittent Fasting?


does intermittent fasting works Also known as Intermittent Energy Restriction, Intermittent Fasting is a diet method involving scheduled meal timings through a cycle of a period of voluntary fasting and followed by a period of non-fasting.

Designed to reduce calorie intake, the dieter is restricted from eating any kind of food except water and tea during the period of fasting . At eating time, or the period of non-fasting, food intake is allowed.

Gaining much popularity lately, IF or Intermittent Fasting was introduced in 2012 by journalist Dr. Michael Mosley in a BBC documentary “Eat Fast, Live Longer” followed by a book “The Fast Diet.”

Later, journalist Kate Harrison released the book “The 5-2 Diet” which she wrote out of her own experience. And subsequently Dr. Jason Fung’s published his book “The Obesity Code” which became a bestseller and made Intermittent Fasting a household name.

Although there is still much that needs to be known as to its long term effects, given the more recent emphasis and practice of this form of diet, the American Heart Association (AHA) has said that intermittent fasting may produce weight loss, it can also help reduce insulin resistance and may  lower the risk of cardiometabolic diseases.

A study conducted in 2019 also concluded that intermittent fasting interventions can help against obesity, dyslipidemia, inflammation, hypertension and insulin resistance.

At any rate, when on an intermittent fasting, although emphasis is on the cycle of the periods of fasting and eating, the dieter must still stick to eating more vegetables and fruits, healthy sources of fats and protein and avoid or lessen the intake of processed foods, refined grains and sugar.

Does Intermittent Fast Work


Kinds of Intermittent Fasting.


There are various methods of doing Intermittent Fasting. A dieter may read through some of these and find something that he or she can be more adaptable to. Just bear in mind that whatever the method you choose, there is one thing common to them all, and that is having a fast (period without any food intake, except water and tea) which is longer than the regular fast our body does overnight or during sleep.

Also, while there are studies  that reveal the weight loss and other benefits of intermittent fasting, there are also groups which appear to be hesitant to recommend the diet especially to those advanced in age or with existing health issues. Others are weary that it may cause muscle loss.

This write up gives you sufficient information to make an informed choice whether or not to try or continue intermittent fasting.

Intermittent fasting may have evolved in the sense of how dieters adapt themselves to the method or how they have modified it in  way to obtain the best benefit for themselves, but here is a lit of the most common types of IF:


Time-Restricted Feeding


Also known as the Time-Restricted Eating (TRE), this method limits the consumption or intake of calories to a fixed number of hours each day.

The eating period may range from a minimum of 4 hours to a maximum of 12 hours. But dieters commonly stick to an 8 hour eating window.

The 8 hour eating period is also called the 16/8 intermittent fasting. This simply means that a period of 16 hours fasting is followed by 8 hours of eating. So for example, when you start your fast at 8 o’clock in the evening, it should end at 12 o’clock at noon the following day. At 12:01 o’clock noon begins your eating period until 7:59 o’clock in the evening to complete the cycle of intermittent fasting. Then the cycle goes on.


Alternate-Day Fasting


As can be easily understood from its name, this method of intermittent fasting consists of day cycles of 1 day for eating and 1 day for fasting alternatively. A dieter can take a whole day as eating day followed by a non-eating or fasting day the next.

This method may prove a little bit difficult for those who are new to fasting because of the length of hours without food. So some dieter modified this method and would take 1 small meal during the fasting day.


Periodic Fasting


This method of intermittent fasting consists of occasional fast followed by days or weeks of eating period.

Although there are no definitive terminologies for this kind of fast, usually a fast for 1 to more days every 1-4 weeks can be considered as periodic fasting.


The 5:2 Diet


The more well known 5:2 intermittent fast is more likened to the periodic and alternate day fast.

What dieters do with this kind of fast is to eat normally for 5 days a week and followed by 2 days of eating only 25% of the regular or usual calories eaten every day.

The 2 day of reduced calorie restrictions is akin to a modified form of fasting specially if only one meal is eaten.


Religious Fasting


Many religions of the world practice some forms of voluntary or religious  fasting.

Such as these is the Ramadan by the Muslims which is considered as almost obligatory and an essential aspect of Islam. Also there are various other forms of fasts practiced by Orthodox Chiristian.



Is It True That We Lose Muscle Mass When  Fasting?


Intermittent fasting is purposed primarily for weight loss and a lot of studies on this idea have centered on this goal.  But it is also a legitimate concern to know if doing the fast can cause muscle loss.

We have to understand that any diet for that matter is incomplete by itself without the complement of a good exercise routine or some form of physical activity.  This holds true with intermittent fasting. When we lose weight it must be understood that it is because we are also losing both fat and lean mass. And lean mass means our muscles.

Losing muscle mass is true not only of intermittent fasting but with all other weight loss diets as well. In fact, in some studies it was found out that during intermittent fasting dieters actually lost minimal amounts of lean mass compared to other diets. But there are also studies which showed no loss of muscle mass at all, and this could be accounted for proper exercise and the kinds of food the dieters ate.

When in an intermittent fasting, it is recommended to incorporate a good exercise routine and probably weight training.  Some researchers agree that with proper diet and exercise, intermittent fasting appears more capable of maintaining lean muscle mass during weight loss than any other non-fast diet methods.


Is Intermittent Fasting the Best Method for Building Muscle Mass?


For this time, it appears that there is not much study made on the topic of whether intermittent fasting can be used to build muscle mass. This is probably because weight loss became the most likely reason for this diet method.

Nevertheless, there is 1 study conducted on 18 young men that can probably give us some insight on the issue of muscle gain. In a period of 8 weeks, these young men underwent a training program. All these men have not done weight training in the past on a regular basis.

While in the program they were made to follow a normal diet and a time-restricted one. Those who are in a restricted diet were required to eat all their food within a period of 4 hours, 4 days every week.

At the conclusion of the study, the time-restricted men were able to maintain their lean body mass with increased strength while those on  a regular diet gained 5 pounds or 2.3 kilos of lean mass and also with increased strength.

The study revealed to us that intermittent fasting is not too effective for muscle gain. This could be attributed to less protein consumed by the time-restricted group as against the control group.

From a scientific perspective there is a good reason why intermittent fasting may not be optimal for muscle gain.  This is because while on  a fast the dieter may have difficulty getting enough calories to build muscle and more so when eating nutrient-dense food that can make them feel full immediately.

To gain muscle mass, one must eat more calories than what is burned by the body.  There should be enough protein to build new tissues in the muscle and enough exercise to trigger muscle growth.

Therefore, if you are really meant to start intermittent fasting, make a good effort to get enough protein even if you have a limited eating time and a good exercise routine or physical activity in order to build and not lose muscle mass. Studies have shown that enough regular protein consumption throughout the day can be good for muscle growth.

With all these being said, it does not mean that it is impossible to gain muscle with intermittent fasting. The fact is that it is just not that easy, and so  if you are seeking to build muscle then intermittent fasting may not be your best alternative.  It is only proven to be very effective in weight loss.


Can Weight Training Help Maintain Muscle Mass During Intermittent Fasting?


Definitely, studies have shown that weight training can greatly help prevent muscle loss and maintain lean mass during intermittent fasting.

In a research conducted on 34 men (experienced weight trainers) for a period of 8 weeks to determine the effects of the weight training three days a week with intermittent fasting, this is what they found:

The men were divided into 2 groups. The time-restricted group and the control group who ate a normal and regular diet. The time-restricted group followed the 16/8 intermittent fasting method. Eating within the 8 hour window.

All the men in both groups were given foods with similar amounts of calories and proteins every day.  They only differed in the timing the foods were given to them.

At the conclusion of the study, researchers found that weight training 3 days a week during intermittent fasting helped those in the time-restricted group to maintain muscle mass and strength while losing 3.5 pounds of 1.6 kilos of fat, as compared to the control group that showed no change at all.

On the other hand, another study found that 20-45 minutes cycling or elliptical exercise 3 times a week helped those who are on an alternate-day intermittent fasting maintain lean muscle mass.

Therefore it can be said that doing exercise is greatly advised to dieters when doing intermittent fasting in order to maintain muscle mass. Just check with your doctor for the safest and most suitable physical activity you can engage in.


Should You Exercise During Intermittent Fasting?


There remains a debate as to whether there is a need to exercise while on an intermittent fast. Although it is not bad to exercise while in any kind of fast, let us look at the studies made on this issue.

In a study conducted on 20 women who fasted against those who did not. Those who exercised did so on the treadmill, 3 days in a week in a session of 1 hour each. It was later found out that –

Both those who fasted and those who did not fast lost almost the same weight and fat and showed no change in their muscle mass.

By these results it is safe to say that it will not matter if you exercise or not during your intermittent fast for as long as your only goal is to lose weight.

Also a word of caution must be said about athletes on serious weight training. You have to understand that fasting can impair your performance while exercising or doing other important physical activity. Intermittent fasting while on weight training is therefore not highly recommended in this instance. In short, doing both at the same time or complementarity is now a matter of your own personal choice.

Some people, however, have done exercise while on a fast. At this particular situation it is recommended that you take a protein supplement of at least 20+ grams immediately after exercise to support a quick muscle recovery, growth and prevent muscle loss.


Proper Nutrition To Prevent Muscle Loss


When you come to a point where you feel that intermittent fasting is worth a try, there are a few things you can do to prevent muscle loss.

One of the most important things you can do to prevent muscle loss while on an intermittent fasting is to exercise. Find a good and suitable physical activity you can engage in to compliment your intermittent fasting.

Find a physical activity that you can do on a regular basis. Fix a goal and modify your physical activity once in a while to avoid monotony. For example if you may want to go to a gym twice to three times a week then get another day to go for biking or a brisk walk along the park.

As much as possible avoid the elevator and take the opportunity to  walk when you can. Park further in a car park and when working in an office environment take a few minutes to stand up and walk around every 1-2 hours. Always emit a vibrant and energetic disposition to remind yourself of your fitness goals. Maintain a healthy disposition and always choose to eat healthy as much as you can.

Always remember that diet and fitness is not a one time life event. It is a lifestyle we need to cultivate. It is a culture of good health that we need to develop.

Being fit and sexy should be an inner inspiration and not merely for others to appreciate and look at. Of course that should come naturally when we are already fit and healthy.

Also, it is advisable to lose weight not too quickly. Allow your body to adjust to your new lifestyle and let it ditch those extra pounds slowly but regularly until your desired weight is attained. Because losing weight too quickly may result in losing fat and lean muscle too.

What we’re saying here is that when on an intermittent fasting, do not drastically reduce your calorie intake in one single go. Although it varies how much weight each person can lose in a given period, experts say it is safe to lose at least 1-2 pounds or 0.45-0.9 kilos per week.

Just keep in mind that you don’t want to lose muscle in the process so keep your exercise and physical activity going. And if muscle loss is a concern to you, keep your exercise and aim for the least weight loss per week.

An additional tip, keep your meal plan loaded from healthy protein and fat sources. Your diet can play an important role in keeping your lean muscle. So never forget your vegetables, fruits, as well as healthy fats and proteins. Avoid if not limit intake of processed, starchy and sugary foods.

Numerous studies have confirmed that with enough protein, the body is able to preserve your muscle even when trying to lose weight. Eat protein from healthy sources by at least 0.7 grams/lb of bodyweight per day (1.6 grams/kg). Loading enough protein while on intermittent fasting is even more important for the body to compensate for the periods that it’s deprived of nutrients during the fast.


Can Dietary Supplements Help Against Muscle Loss


Certainly, a safe and effective dietary supplement can be taken while on intermittent fasting. Just study the supplement you have chosen and find something that is complementary and not interfere with your fasting.

When choosing a supplement, consider having creatine and protein. These two are very essential to maintain muscle mass. If you feel that you are not eating enough protein then get a supplement to augment your diet. A supplement can come in handy and is specially needed when you are active physically to improve performance in exercise and aid in muscle growth.

Creatine is also very helpful. It is a molecule that is naturally occuring in the body. It’s composition in the body can be increased by taking creatine supplements. Creatine is known to improve strength and endurance during weight training by 5-10 percent on the average.

Supplements with amino acids  to include protein and BCAA supplements while on intermittent fasting also appears to be helpful in retaining muscle  mass. These supplements actually signal to your body that you are not on  a fast. With a good intake of protein, even fasting for 16 hours does not appear to affect your muscles at all, unlike sticking only to regular normal diets.

In short, taking supplements during intermittent fasting is really helpful and beneficial to preventing muscle loss.




As a popular form of diet, intermittent fasting is the cycle between periods of fasting and eating. It has been found to be an effective method for weight loss.

Intermittent fasting includes time-restricted eating, periodic fasting, the 5:2 diet, alternate-day fasting and religious fasting.

Although effective for weight loss, there are concerns that it may affect lean muscle and cause muscle loss. To address this concern, it is advised to compliment intermittent fasting with regular exercise and a diet with sources from healthy proteins and fats. Otherwise, a dieter may take protein, creatine supplements or additionally those with amino acids especially those doing weight training.

Also, it is advised that weight loss should be slow and not drastic when using the intermittent fasting method in order to help maintain lean muscle.

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  • St-Onge MP, Ard J, Baskin ML, Chiuve SE, Johnson HM, Kris-Etherton P, Varady K, et al. (American Heart Association Obesity Committee of the Council on Lifestyle and Cardiometabolic Health; Council on Cardiovascular Disease in the Young; Council on Clinical Cardiology; and Stroke) (February 2017). “Meal Timing and Frequency: Implications for Cardiovascular Disease Prevention: A Scientific Statement From the American Heart Association”. Circulation. 135 (9): e96–e121. doi:10.1161/CIR.0000000000000476. PMID 28137935.


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