Our entire body is made up of proteins including every single cell, tissue, and organ. Adequate protein consumption is perhaps the most important daily “must do” to power a person throughout the day. There are many different protein sources, but not all proteins are created equal. The difference comes from whether the protein is classified as a complete or incomplete protein.
A complete protein is a protein that contains the just perfect amounts of all nine essential amino acids needed in a human diet. These amino acids are regarded as 'essential' because they cannot be created by the body itself but rather must be consumed through diet. Health benefits of these amino acids include improved energy and mood, lean muscle and fat burning capabilities.
A protein source that lacks even one essential amino acid is considered an incomplete protein. In fact, even if the protein does have all nine essential amino acids, it can still be considered incomplete if it does not have the necessary amounts of each essential amino acid.
Most foods on the market today are 'incomplete' protein sources because they lack these amino acids. In fact, when it comes to complete protein, whey is the one of the most important sources of it.