The pain in the stomach when you eat is caused by pyloric obstruction, acute pancreatitis, etc. If it is gastric ulcer, irritable bowel syndrome, etc., you don’t need to fast for the time being. 1. Pyloric obstruction: the exit of the stomach to the intestine is the pylorus, when there is pyloric obstruction will cause eating and drinking abdominal pain phenomenon, nausea, vomiting and other symptoms, need to fasting and hospitalization, to take gastrointestinal decompression therapy. 2. Acute pancreatitis: acute pancreatitis can be induced by eating greasy food and overeating, and the pain is characterized by persistent and progressive aggravation of pain, like a knife cut, and in severe cases, it can lead to shock, which requires fasting and immediate treatment with medication or surgery. 3. Cholecystitis: The abdominal pain caused by this disease is generally not required to fast. After ultrasound diagnosis, only symptomatic treatment is needed. 4. Gastric ulcer: this kind of patients choose light diet and liquid food will not cause severe pain, so do not fast, but need to take gastric drugs such as omeprazole and other drugs. Abdominal pain should not be diagnosed and treated on its own, it is recommended to consult a doctor in a timely manner in order to avoid delaying the condition.