To conserve body protein for its vital functions and not use it to provide energy, you should eat adequate amounts of carbohydrate and fat to conserve protein for other functions. Proteins play various roles other than to provide energy in the body which includes; building and repairing body tissues; they also production of hormones; They catalyze reactions; enzymes are proteins that increase the rate of chemical reactions in the body; they are also important in formation of antibodies which serve to protect infection, illness and diseases. Eating adequate amounts of carbohydrates and fat, they will serve as sources of energy instead of proteins.