Intermittent fasting is defined as an eating pattern that cycles between periods of fasting and eating. It has several popular methods and the most common being 16/8 methods. Studies have observed that intermittent fasting doesn’t help you gain muscle. Therefore, a protein supplement that contains a sufficient proportion of BCAAs taken during the eating window or eating phase may help in that respect (104). Whey supplements can be the right choice for that purpose. However, you shouldn’t take them during the fasting window as it contains calories and will break your fast.