One of the most popular uses of BCAAs is to increase muscle growth. The BCAA leucine activates a certain pathway in the body that stimulates muscle protein synthesis which is the process of making muscle. In one study people who consumed a drink with 5.6 grams of BCAAs after their resistance workout had a 22% greater increase in muscle protein synthesis compared to those who consumed a placebo drink. That being said this increase in muscle protein synthesis is approximately 50% less than what was observed in other studies where people consumed a whey protein shake containing a similar amount of BCAAs