Protein is essential for almost every process in the human body. It is vital that we eat enough each day to support theses processes. It is said that we should aim for between 45g and 70g a day when working out. To put that in context, an egg has about 6g of protein and a chicken breast about 25g.
A diet too low in protein can result in losses in muscle mass and lean tissue. In turn, this causes a reduction in the metabolic rate, meaning we burn calories less efficiently.