Protein can provide calories. 1 gram of protein can provide about 4 calories to maintain normal metabolism and regulate the physiological functions of the body and repair cell tissues. Protein is one of the three major energy substances, usually the body’s fat and carbohydrates provide insufficient calories, can not meet the physiological needs, protein can be converted to heat by gluconeogenesis, for the body to utilize. The main physiological function of protein is not to provide energy, but also has an important role in the composition of human muscle tissue and participate in the construction of the immune system. Usually can moderate intake of food rich in high quality protein, such as eggs, lean meat, fish, milk, goat’s milk, soybeans, etc., a balanced diet, can provide a variety of high-quality protein for the body, to maintain the body has enough protein.