After overeating, the body will lose weight, which is commonly seen in patients with gastric ulcer or gastritis after a sudden large amount of food, the stomach in order to adapt to more food continue to secrete gastric acid to dilute the absorption of various foods, when the patient in the overeating and suddenly reduce the amount of body functions can not adapt to, gastric acid continues to secrete erosion to the stomach itself, so resulting in gastric ulcers, gastritis, generally easy to bloating and diarrhea symptoms after overeating. In addition, the body becomes thin after overeating is also common in patients with pancreatitis, easy to overeat after a sudden sharp pain in the upper abdomen and even pain in the lower back, serious patients will be vomiting blood, vomiting blood, fecal occult blood positive, after treatment need to be strictly controlled diet and thus become thin.