Branched Chain Amino Acids (BCAAs) are Leucine, Isoleucine and Valine. They are considered to be essential amino acids because humans could not survive unless they were present in their diet. BCAAs are required to maintain lean tissue and studies have shown that they help to preserve your stores of glycogen. BCAAs also prevent tissue breakdown during training. Unlike other amino acids BCAAs are not metabolised in the stomach and are instead metabolised directly in the muscle. This unique quality means that they build lean tissue and stop catabolism. These unique amino acids (Leucine, Isoleucine and Valine) cannot be synthesised by your body so they are essential to your growth.