Fast hunger is not necessarily good metabolism. It may be caused by good metabolism, low calorie intake, fast gastrointestinal peristalsis, hyperthyroidism, diabetes and so on. 1. good metabolism: generally in the developmental period of adolescents, the body develops quickly, eat more, digestion and absorption is also fast, metabolism is strong, will be hungry fast, is a good metabolism of a physiological phenomenon. 2. Eating low calorie: If you eat spinach, apples and other low-calorie vegetables and fruits more, lean meat, eggs and other foods with high protein and fat content eat less, can provide the body with low calories, it is easy to starve quickly. 3. Gastrointestinal peristalsis: Irritable bowel syndrome causes gastrointestinal peristalsis to accelerate, gastrointestinal contents of the discharge accelerate, which will cause fast hunger. 4. Hyperthyroidism: increased secretion of thyroid hormones, the body’s metabolic level increases, easy to starve after eating, this situation belongs to the pathologic metabolism fast. 5. diabetes: due to part of the glucose out of the body, can not be completely absorbed by the body, abnormal metabolism, easy to hungry fast, at the same time there will be more drinking, urination and other symptoms. Hungry fast exclude exercise consumption and other physiological reasons, may also be other reasons, should be timely under the guidance of the doctor to identify the causes, and timely and reasonable treatment.