There are many reasons for loss of appetite, and the common ones are gastritis, gastroesophageal reflux and intestinal obstruction. 1. Gastritis: refers to acute or chronic inflammation of gastric mucosa caused by many different reasons, which is mainly manifested as epigastric discomfort, nausea, vomiting, loss of appetite and other symptoms. 2. Gastroesophageal reflux (GERD): Reduced function or structural damage of the lower esophageal sphincter can lead to reflux of gastric contents into the esophagus, with typical symptoms of heartburn and reflux, and accompanied by loss of appetite and nausea in some patients. 3. Intestinal obstruction: Diseases caused by various reasons that the intestinal contents cannot run normally and pass through the intestines smoothly. The main manifestations are abdominal pain, loss of appetite, abdominal distension, stopping defecation and gas evacuation. Loss of appetite may also be related to other causes, such as chronic cholecystitis, etc. If long-term loss of appetite, or accompanied by abdominal pain, nausea and other symptoms, you need to consult a doctor in a timely manner, under the guidance of a professional physician to clarify the cause of the disease, standardized treatment.