Excessive fasting puts the body in a state of starvation for a long time to achieve the purpose of fat burning and weight loss, which is a wrong approach. The human body in a state of hunger for a sustained period of time, will provide energy through the decomposition of glycogen, protein and fat in the body, but generally will first consume the reserve glycogen, the content of the reserve glycogen in each person’s body is different, the time to start consuming fat is different, most people will start consuming fat a day after they stop eating. Since the intestine does not take in certain nutrients and cannot meet the energy needs of the body, in order to maintain the normal physiological activities of the body, it is necessary to consume fat in the body to provide energy, generally by first consuming sugar in the blood as well as liver glycogen and muscle glycogen, to provide energy for the body. When glycogen depletion can not meet the body’s needs, the body is still in a state of hunger, it will begin to consume protein, fat. Prolonged starvation, relying on fat burning to make weight reduction, will cause the function of the tissues and organs in the body to decline, posing a threat to human health. Therefore, people who need to control their weight are not recommended to simply rely on excessive dieting and consume fat through starvation methods to achieve weight loss. You can properly control the diet, reduce the intake of fats and increase exercise, such as swimming, jogging and other ways. The process of weight loss is gradual, not to rush to achieve the purpose of weight loss, and use some methods that are not conducive to health.