Muscle Feast BCAA is formulated with the optimal 4:1:1 ratio of leucine, isoleucine, and valine. They are called branched chain because their structure has a ‘branch’ off the main trunk of the molecule. The combination of these three essential amino acids makes up approximately one-third of skeletal muscle in the human body. In order to get energy, the body can actually break down muscle to get these BCAAs. Therefore, by supplying them during or after a workout, muscles and other tissues are spared from breakdown, which occurs as a natural part of metabolism.