Essential Amino Acids cannot be produced in the body and must be consumed. EAAs are made up of 9 essential amino acids, including the Branch Chain Amino Acids (leucine, isoleucine, valine) and the other 6 EAAs (histidine, lysine, methionine, phenylalanine, threonine, tryptophan). Amino acids are the building blocks of protein. This is why EAAs are key to protein synthesis to build muscle tissue!