Vomiting once eating may be caused by anorexia, intestinal obstruction, acute inflammation of the digestive tract, malignant tumor of the digestive tract, acute heart failure and other causes. 1. Anorexia nervosa: this disease is related to genetic, psychological and social environment, etc. Patients with long-term excessive dieting, vomiting, etc. to reduce body weight, there may be mental anxiety and nervousness which may lead to the occurrence of this symptom. 2. Intestinal obstruction: intestinal occupation, intestinal torsion, mesenteric blood transport disorders, intestinal nerve dysfunction and other factors lead to intestinal stenosis and blockage of intestinal lumen, intestinal peristalsis disappears, and the pressure of the digestive tract above the site of obstruction rises significantly, so that this symptom occurs. 3. Acute inflammation of digestive tract: when infection, trauma, stress and other factors lead to acute gastritis, acute pancreatitis, acute cholecystitis and other acute inflammatory lesions of digestive tract, nausea, vomiting, abdominal pain, fever and other symptoms will appear. 4. Malignant tumor of digestive tract: in the middle and late stages of malignant tumors of digestive tract such as gastric cancer, liver cancer, gallbladder cancer, pancreatic cancer, colon cancer, etc., the cancerous tissues widely invade and lead to digestive dysfunction, so nausea symptoms will appear. 5. Acute heart failure: due to diastolic and systolic dysfunction of ventricle, resulting in blood circulation disorder, obstruction of venous return in digestive tract and other tissues of the whole body, a large amount of venous blood is stagnated in the digestive tract, and nausea and abdominal distension will also occur. Vomiting as soon as you eat may be related to a variety of factors, and it is recommended that you seek medical attention for a definitive diagnosis.