Lack of appetite may be caused by chronic gastritis, gastric ulcer, gastrointestinal dysfunction and other digestive diseases, but it may also be caused by mental stress and other factors. 1. Chronic gastritis: chronic gastritis is a chronic inflammation of the gastric mucosa caused by various factors, usually chronic gastritis does not have obvious symptoms, but some patients may show discomfort in the upper and middle abdomen, fullness, dull pain, lack of appetite and other symptoms. 2. Gastric ulcer: Gastric ulcer belongs to a kind of peptic ulcer, which refers to the inflammatory defect of the mucous membrane of the stomach, often related to gastric juice. This disease is mainly manifested as epigastric pain, but some patients may also have symptoms such as lack of appetite and belching. 3. Gastrointestinal dysfunction: Gastrointestinal dysfunction caused by various factors may cause the peristaltic function of the gastrointestinal tract to be weakened, which may cause the accumulation of food in the gastrointestinal tract, triggering the symptoms of lack of appetite. 4. Mental stress: If you are in a state of prolonged mental tension, it may also indirectly lead to mental exhaustion, loss of appetite and other symptoms. There are many reasons for the lack of appetite, if the symptoms are not relieved after the recovery of the mental state, or in this state for a long time, it is recommended to go to the hospital to find out the specific causes of the symptomatic treatment under the guidance of the doctor.