BCAAs & amp; EAAs are specific types of amino acids. EAAs are essential amino acids and refer to the group of eight amino acids that cannot be synthesized by the body but must be supplied through the diet. The eight EAAs are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Three of these – leucine, isoleucine and valine – also belong to the category BCAA, which refers to branched-chain amino acids. EAAs are of particular interest as supplements for those who do not get enough amino acids through their regular diet. BCAA supplements are great for those who focus on serious strength training. The three BCAAs make up about a third of skeletal muscle and have been shown to be important for muscle building and effective in slowing muscle breakdown. BCAAs are metabolized by muscle tissue, making the amino acids readily available for building muscle or as building blocks for muscle.