The human body requires protein; it is contained within every cell in the human body and is essential for building and repairing tissues. The body uses protein to manufacture hormones, enzymes, and many other chemicals in the body. It is a very important component of muscles, bones, cartilage, blood and skin.
Fat, carbohydrates, and protein are all needed in relatively large quantities. Vitamins and minerals are also essential, but only in very small amounts.
The body does NOT store protein. A constant supply of protein is essential since there is no reservoir of protein that the body can draw from when needed.