Branched-Chain Amino Acids (BCAAs) are a group of three essential amino acids: leucine, isoleucine, and valine. They are called branched-chain because of their chemical structure, which has a ‘branch’ off the main trunk of the molecule. BCAAs are essential because they cannot be produced by the body and must be obtained from the diet. They are widely used in the fitness and bodybuilding community due to their ability to promote muscle protein synthesis, increase muscle growth, and reduce muscle soreness and fatigue. They also play a role in regulating blood sugar levels and can provide the body with energy during prolonged exercise. 

The BCAA ratio refers to the proportion of branched-chain amino acids – leucine, isoleucine, and valine – typically found in BCAA supplements, often represented as 2:1:1, denoting twice as much leucine as isoleucine and valine.