Intermittent fasting is an increasingly popular way among people looking for weight loss without going through prolonged periods of strict dieting. There are several methods of fasting with variable results. One of the most popular ways is Time Restricted Fasting or 16:8 method. Other plans include Alternate Day Fasting (ADF), 5:2 fasting approach, Full day fasting, etc. Most beginners prefer the TRF approach as it provides regular opportunities for feasting while still being on a diet. It is also beneficial in controlling insulin sensitivity and improving insulin resistance. The most significant advantage of regulating insulin function is avoiding diabetes, which is a direct result of insulin resistance.

There is a debate among weight watchers about the effect of intermittent fasting on losing muscle mass. It is well known that loss of muscle results in decreased metabolism and can be counter-productive in maintaining weight loss in the long run. So one needs to look carefully at the relationship between fasting and muscle loss.

Whenever someone undergoes weight loss, it includes both fat losses as well as depletion of lean mass, which is everything besides fat, including muscles. Most of the research on intermittent fasting has focused on weight loss as this the primary purpose of the diet itself. The limited research that has been done to find the correlation between muscle loss and fasting has produced conflicting results and claims. Some studies indicate a small amount of muscle loss in the range of a couple of pounds (roughly one KG) over several months of consistent fasting. Other studies indicate no significant measurable loss at all. Instead, fasting helped improve metabolism, reduced cholesterol, triglycerides, and waist circumference. A more recent study in 2016 even indicated that fasting had less impact on lean mass compared to caloric restriction. Also, the calorie-restricted diets increased the production of the hormone ghrelin, which is known as the hunger hormone compared to fasting individuals. The hunger and cravings play a vital role in deciding how likely it is for a person to stick to a diet. Some studies even indicate better lean mass preservation compared to other dieting methods.

Another question is, can one gain muscle during intermittent fasting? To make it clear, the first thing to gain muscle is to have enough calorie intake over calories consumed. There should also be a sufficient supply of proteins to build muscle tissues. Diet should be backed up by exercise to stimulate growth. Usually, it is not easy to maintain all these three prerequisites while fasting. Most individuals struggle to keep calorie intake during the limited feasting window. Those who do cannot find the right balance of proteins and carbs. And lastly, exercise is usually challenging from psychological and physical points of view due to reduced performance during the fasting window. So the idea of muscle gain though technically possible, isn’t practical for most of the average dieters during intermittent fasting.

However, moderate exercise, along with proper intake of proteins and amino acids at regular intervals during fasting, should be beneficial in retaining and gaining muscle mass while losing weight. It is also well established that rapid weight loss (more than 1-2 pounds per week), leads to the possibility of losing lean mass, including muscles. In such a scenario, exercise and proper dosage of proteins can help retain muscle mass. The protein intake can be in the form of natural foods or dietary supplements though the former is preferred. Nutritional supplements should be used when it is not possible to cover the required protein quota for a healthy human being through regular meals. Protein intakes of around 0.7 grams/lb of body weight per day (1.6 grams/kg) may be appropriate during weight loss.

It is worth noting that all this debate is based on the assumption that one may lose muscles due to a lack of nutrition during fasting. A balanced diet with a sufficient amount of proteins should address this concern. Furthermore, unless one undertakes extreme forms of fasting with a prolonged period of remaining hungry and extremely short windows of eating allowance, one should not worry too much about muscle loss. The Time-Restricted Fasting (16:8 method) or 5:2 fasting (Five days of eating with two days of fasting per week) allow enough opportunities to replenish the nutritional deficiencies, and a balanced diet should help maintain lean mass while losing fat. The above, along with regular intervals of moderate exercise, should be sufficient for average individuals to reap the benefits of fasting without any adverse impact. One should also keep in view that too many calories during the feast period and choice of unhealthy saturated fats, sugar, and carbs can have a negative impact resulting in rapid weight gain instead of a loss. In short, thought intermittent fasting allows regular intervals of feasting during the diet period; it doesn’t give one a license of indulging in binge eating. Fasting is all about regulating your hormones to better cope with consuming energy and breaking fat cells. It requires a particular discipline in life with a proper balance of diet and exercise if one is serious about losing weight on a long term basis