Does Intermittent Fasting Make You Gain or Lose Muscle?

Intermittent  the most popular diet pattern, trending in these days.

There are lots of different types, but what they have in common is fasts that last longer than a normal overnight fast.

While research has shown that this can help you lose fat, some people are concerned about that intermittent fasting may also cause muscle loss.

This article explains you everything you need to know about the effects of intermittent fasting on your muscles.

Types of Intermittent Fasting

Although intermittent fasting is very common or popular, there is sometimes confusion about what it actually is.

This is probably because intermittent fasting is a broad term, explaining several specific types of eating. Here are the most common types (1):

Time-Restricted Eating

Time-restricted eating (also known as time-restricted feeding) restricts all calories to a certain periods of each day.

This may range from 4–12 hours, but an 8-hour eating period is popular.

Alternate-Day Fasting

As the name suggests, alternate-day fasting consists of alternating between fasting days and eating days. This means you fast every other day.

While some people don’t eat anything on the fasting days (true fasting), it is more common to take one small meal on the fasting day (modified fasting).

Periodic Fasting

Periodic fasting (also called as whole-day fasting) consists of irregular fasts, separated by few days or weeks of normal eating.

While exact definitions differ, programs involving fasting for one or more days every 1–4 weeks are usually regarded as periodic fasting.

The 5:2 Diet

The common 5:2 diet is very similar to alternate-day and periodic fasting.

It involves eating normally for five days in a week and taking about 25% of your normal amount of calories two days in a week (2).

The very low-calorie days could be regarded as a form of modified fasting, especially if you only eat one meal.

Religious Fasting

Many different religions have regular duration of fasting.

Examples include the month of Ramadan practiced by Muslims and various fasts related to Orthodox Christianity (3).

Do You Lose Muscle When Fasting?

Nearly all studies of intermittent fasting have been performed for weight loss purposes (1).

It is important to notice that without exercise, weight loss will often come from a loss of both fat mass and lean mass. Lean mass is everything besides fat, including muscle (4).

This is true for weight loss caused by both intermittent fasting and other diets.

Because of this, some studies have shown that few amounts of lean mass about 1 kg or 2 pounds may be lost after several months of intermittent fasting (1).

However, other studies have shown that there was no loss of lean mass (56).

In fact, some researchers think that intermittent fasting may be more effective for supporting lean mass during weight loss than non-fasting diets, but more research is required on this topic (7).

Altogether, it is likely that intermittent fasting will lead to lose more muscle than other weight loss diets.

It Probably Isn’t the Best Method for Gaining Muscle

There is very confined research on whether or not it is possible to gain muscle while following intermittent fasting.

This is probably because weight loss is the topic of interest in most studies on these diets.

However, one study of intermittent fasting and weight training provides some elementary information about muscle gain (8).

In this study, 18 young men finished an 8-week weight training program. They had not previously performed weight training regularly.

The men followed either a normal diet or a time-restricted eating plan. The program needed them to take all their food in a 4-hour period on 4 days each week.

By the end of the study, the time-restricted eating group individuals had maintained their lean body mass and raised their strength. However, the normal diet group gained 5 pounds (2.3 kg) of lean mass, while also rising their strength.

This could mean that intermittent fasting is not a very good for muscle gain. This may be because the time-restricted eating group ate less protein than the normal diet group.

There are a few other reasons based on science ,why intermittent fasting may not be ideal for muscle gain.

For gaining muscle mass, you must take more calories than you burn, consume sufficient protein to build new muscle tissue and do enough exercise stimulus to cause growth (91011).

Intermittent fasting could make it hard to get sufficient calories to build muscle, particularly if you are eating nutrient-rich foods that fill you up easily (12).

Moreover, it can be different to get sufficient protein when eating less often than with a normal diet.

Some research has also shown that eating protein on regular basis throughout the day could promote your muscle build up (1314).

All of these reasons don’t essentially mean that it is not possible to gain muscle while following intermittent fasting, but that it may not be the easiest or simplest diet for gaining muscles.

Weight Training Can Help You Maintain Muscle During Intermittent Fasting

Research has shown that weight training can help in preventing muscle loss during your weight loss journey. (15).

What’s more, some studies have shown this particularly in relation to intermittent fasting (816).

One 8-week study examined the combination of intermittent fasting and weight training three days in a week (16).

The researchers divide 34 men who were very experienced with weight training into two groups: a time-restricted eating group (taking all calories in 8 hours in a day) and a normally eating group.

Both groups were fixed the equal number of calories and amount of protein each day, and just the timing of taking food varied.

By the end of the study, neither group had lost muscle mass or strength. However, the time-restricted group lost about 3.5 pounds (1.6 kg) of fat, while there was no change in the normal diet group.

This shows that weight training for three days in a week may help maintain muscle when they lost fat during intermittent fasting.

Other research on alternate-day fasting has shown that 25–40 minutes of exercise on a bike three times each week can help maintain muscle mass during weight loss (17).

Overall, doing exercise is highly suggested for maintaining muscle during intermittent fasting (816).

Should You Exercise While Fasted?

Even among those who use intermittent fasting, there is an argument about whether or not to exercise during your fasting period. Lots of studies have also looked into this.

One 4-week study followed 20 women performing fasted against non-fasted exercise on a treadmill. Participants exercised three days in a week for one hour every session (18).

Both groups lost the same amount of weight and fat, and neither group had any change in lean mass. On the basis of these results, it may not matter whether or not you exercise fasted if your goal is weight loss.

However, it is possible that training fasted could disrupt your exercise performance, especially for serious athletes (19).

Because of this reason, studies of intermittent fasting and weight training have not used exercise during fast (816).

Overall, it appears that exercising while fasted may be a case of personal choice.

It will pehaps not make your exercise more effective, and it’s even possible that exercising during fast will reduce your performance.

However, some people enjoy doing exercise while fasted. If you prefer to do this, it is suggested that you get 20+ grams of protein soon after exercising to promote muscle recovery (19).

Nutrition Strategies to Support Your Muscles

If you prefer to use intermittent fasting as a tool for weight loss and health, there are so many things you can do to maintain as much muscle as possible.

As discussed, exercising — particularly weight training — can help maintain muscle mass. A slow and steady rate of weight loss may also can be helpful.

Research has shown that you have more chances to lose lean mass, including muscle, when you lose weight fastly(20).

This means that if you are performing intermittent fasting, you should try to not excessively reduce your calorie consumption all at once. Try to reduce gradually.

While the perfect rate of weight loss may differ, many experts suggest 1–2 pounds (0.45–0.9 kg) in a week. However, if maintaining muscle is your first preference, you may want to shoot for the lower end of this range (2122).

Along with the rate of weight loss, the composition of your diet can play a key role in preserving muscle during intermittent fasting.

It doesn’t matter which type of diet you follow, getting enough protein is essential. This is mainly true if you are trying to lose fat.

Several studies have shown that following a diet filled sufficient protein can help maintain muscle during fat loss (2324).

Protein consumption of about 0.7 grams/lb of bodyweight each day (1.6 grams/kg) may be apt during weight loss (2325).

It is possible that enough protein intake is especially important when practicing intermittent fasting, since your body will go for longer periods of time without getting nutrients.

Dietary Supplements to Support Your Muscles

If you want to preserve or gain muscle during intermittent fasting, some dietary supplements may be helpful.

However, it should be noted that, when you want to take the supplements, as this could interrupt with the outcomes of your fasting.

Supplements During Your Feeding Periods

Two of the most important supplements to think about are protein and creatine.

While protein supplements are not required if you get adequate protein from your diet , they can be a convenient way to ensure that you get enough.

Especially if you are physically active, protein supplements may help improve muscle size and exercise performance (26).

In addition to protein, creatine supplements can support your muscles.

Creatine is a molecule that is found naturally in your body. You can increase the amount of creatine in your cells via dietary supplements (27).

Creatine supplements are particularly helpful if you exercise. It has been estimated that creatine increases the strength gains from weight training by 5–10%, on average (2829).

Supplements During Your Fasting Periods

You may wonder if you should take protein, creatine or other supplements such as BCAAs (branched chain amino acid) during your fasting durations. This is mainly due to a thought that these periods will negatively affect your muscles.

However, as explained in this article, small periods of fasting are possibly not a concern for muscle loss (716).

What’s more, some of the health benefits of intermittent fasting are possibly due to the fact that your body is not getting any nutrients (30).

This mild stress on your body may strengthen it to fight off larger fears, such as disease, in the future (31).

If you take supplements containing amino acids (including protein and BCAA supplements) during your fasting periods, you are giving signals to your body that you are not fasting (32).

Moreover, if you get adequate protein in your feeding period, fasting for 16 hours does not appear to be harmful to your muscles, compared to a normal diet (16).

Overall, it is unexpected that you need to take dietary supplements during your fasting periods. Some supplements, like creatine, may even be more beneficial when taken with food (33).

Intermittent fasting is a popular dietary program that have fasting periods longer than a usual overnight fast.

There are so many different types of intermittent fasting, such as time-restricted eating, alternate-day fasting, periodic fasting, the 5:2 diet and religious or ethical fasting.

Intermittent fasting possibly does not lead to more muscle loss than other weight loss diets.

However, including exercise, particularly weight training, to your intermittent fasting program can help you maintain muscle mass.

However, whether or not you exercise during fasting periods is depends upon you. Fasting perhaps does not add benefits, and it could negotiate your optimal exercise performance.

Targetting for a slow rate of weight loss and taking adequate protein can help you maintain muscle during intermittent fasting.

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