Essential amino acids
Amino acids are the molecules that make up proteins when they are linked up. There are certain essential amino acids, namely they are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
All of these must be obtained from one's diet. If they are not, the body will use existing proteins, such as muscle mass, to obtain them.
