Intermittent fasting is a popular way of eating. Although there are various types of intermittent fasting, the main idea is that there are pre-determined times when you restrict calories while the rest of the time you can eat your usual diet. There is a good amount of research being done on this type of eating to determine if the pattern is effective for long-term health benefits. But if you’re looking to build muscle., is intermittent fasting right for you?


There are two main types of intermittent fasting: Time Restricted Feeding (TRF) and a 5:2 format. In TRF, you eat all your daily calories within an 8-hour period of time, and fast the remaining 16 hours of the day. For example, you eat from 8 a.m. to 4 p.m., eating nothing else before or after.

The 5:2 format is followed in the popular Fast Diet where two non-consecutive days in the week are spent fasting, allowing approximately 25 percent of your daily calorie needs (about 500 calories for an average adult). During the remaining five days, a usual diet is consumed. The only rule is not what you eat, but when and how many calories you consume on fast days (if you are doing the 5:2 method). However, if you eat too much or too little on usual eating days, it can impact the times or days that you fast.

Symptoms of either method vary from person to person and include fatigue, headaches, hunger, and irritability. You may also experience gastrointestinal issues like gas, bloating, and constipation, depending on how your body reacts to the shift in the timing of your food and the amount eaten.


If you plan on working out while practicing intermittent fasting, Dana Angelo White, MS, RD, ATC. certified athletic trainer and sports dietitian at Quinnipiac University in Hamden, CT points out potential issues you may face. “The calorie deficit, especially on fasting days can have a negative impact on performance. The lack of fuel can interfere with proper energy production and muscle recovery,” says White.

If you do plan on working out, and are looking to build muscle, White suggests following the TRF model. The usual eating window on TRF is 8 a.m. to 4 p.m. or 12 p.m. to 8 p.m. to elongate the overnight fasting period. “I would suggest a workout in the middle of this window so calories are coming in before and a recovery meal can come after the workout,” explains White.

Toby Amidor is the owner of Toby Amidor Nutrition and best-selling author of Smart Meal Prep for Beginners, The Easy 5-Ingredient Healthy CookbookThe Healthy Meal Prep Cookbook, and The Greek Yogurt Kitchen.