Proteins are the building blocks of muscles. Proteins are made up of twenty amino acids, which include 9 essential amino acids. Therefore, the essential foods for muscle building are those that contain these amino acids, essential as well as non-essential. Since these essential amino acids are not produced by our body, they must be provided by external sources i.e. our diet.
In order to build muscles, one must consume a healthy, balanced diet with an adequate intake of protein rich foods at every meal. The common muscle building foods that are derived from animal sources include chicken, fish, eggs and milk. For a vegetarian person, the protein-rich food options are legumes, soy, vegetables, beans and grains.
However, the plant derived protein is considered to be inferior to the protein available from animal sources because it lacks in one or more of the essential amino acids. This is one reason why some bodybuilders rely on products such as protein supplements.