Early stage gastric cancer is often asymptomatic, and those with symptoms are not specific. Nausea, loss of appetite, epigastric heaviness, vague pain, and wasting often precede other symptoms. Malnutrition is mostly due to excessive blood loss, protein loss, or mechanical obstruction affecting feeding. In some patients, gastric fluid deficiency (gastric hydrochloric acid and protease deficiency) or gastric acid deficiency may exist several years before the onset of gastric cancer. Nutritional support for gastric cancer should be given as much attention as surgery, radiotherapy and chemotherapy, and strong measures should be taken. According to the tumor site, disease stage and whether there is gastric dysfunction, a corresponding dietary guidance plan should be formulated. Postoperative nutritional disorder – dumping syndrome may occur in some patients with surgical resection. Patients who have lost the chance of surgery in the progressive stage need to be given appropriate dietary adjustment. Any food hobbies of the patient, unless particularly harmful, should be satisfied as far as they are comfortable. In advanced disease, the patient can tolerate only a liquid diet or must rely on parenteral nutrition. Gastrectomized patients may experience nutritional impairment or difficulty in weight recovery. This is mainly due to inappropriate feeding due to anorexia or dumping syndrome, or malabsorption after eating. It is difficult for patients to eat large amounts of food at one time after total or subtotal gastrectomy, so they need to develop the habit of eating small and frequent meals. Gastrectomy patients often have weight loss, mostly due to fear or apprehension about eating. Some patients have symptoms when eating, which may be related to the way of eating, food volume and type. In addition to dumping syndrome and hypoglycemia, malabsorption and steatorrhea can occur in patients undergoing gastric surgery. About 10% of patients have typical steatorrhea due to accelerated peristalsis, loss of gastric lipase or inadequate pancreatic-biliary fluid secretion. Digestion is reduced due to interference with the entry of food into the small intestine and the release of hormones and enzymes from the small intestine. Patients may change from lactose tolerance to intolerance after surgery, mainly due to food diversion to the distal small intestine or rapid passage through the proximal small intestine. Prolonged malabsorption and restricted feeding lead to anemia, osteoporosis and deficiencies of certain vitamins and minerals. Iron and vitamin B12 cause iron deficiency and malnutrition anemia, respectively. Under normal conditions gastric acid reduces iron complex and promotes its absorption. Iron deficiency can be caused by decreased acid secretion, excessive transit, decreased area of iron absorption, or blood loss. Reduced gastric mucosa and inadequate production of endocannabinoids reduce vitamin B12 absorption; bacterial overgrowth in the proximal small intestine or input collaterals depletes vitamin B12, as bacteria can compete with the host for vitamin utilization. Thus, prophylactic injections of vitamin B12 are often required after gastric surgery. Growth inhibitors are often used to slow gastric emptying in patients with tachypnea or dumping syndrome. Acarbose, an alpha glycoside hydrolase inhibitor, was originally used in type 2 diabetes and is now used in the treatment of some patients with dumping syndrome. Acarbose inhibits the digestion and absorption of starch, sucrose and maltose and may alleviate the dietary hypo- or hypoglycemia associated with dumping syndrome, but may exacerbate underlying chronic flatulence and diarrhea. Postoperative diarrhea caused by too little food and excessive bowel movements in gastric cancer patients can both lead to weight loss and malnutrition. Nutritional components should be provided to improve nutritional status and quality of life. Fats and proteins are more easily tolerated than carbohydrates because carbohydrates are slower to hydrolyze into osmotically active substances. Monomeric carbohydrates such as lactose, sucrose and glucose hydrolyze more rapidly and must be limited, whereas complex carbohydrates (starch) are tolerated. Because liquids enter the jejunum quickly, some patients with dumping syndrome do not tolerate it easily, so the amount of liquids should be limited during meals or between meals, and lying down immediately after meals can reduce symptoms. Fiber slows down the passage of the stomach and intestines, slows down the absorption of glucose and reduces the release of insulin, which is beneficial to reduce the symptoms of dumping syndrome. Pectin, a dietary fiber found in beverages, vegetables, and gums, is used to treat dumping syndrome by slowing carbohydrate absorption and lowering hepatic anti-insulin substances, thereby reducing the feedback elevation of insulin. Care must be taken in the application of dietary fiber, as several cases of obstruction have occurred with the use of gums and mucilage, especially in large amounts and without adequate water intake. In order to avoid dumping syndrome and to maintain a proper weight and nutritional status, a diet with medium amounts of fat (30-40% of calories), small amounts and monomeric carbohydrates and high protein (20% of calories) should be given. Milk is especially intolerable in large amounts for almost all post-gastric patients, and patients are more tolerant of lactose in cheese and yogurt than in cow’s milk. Vitamin D and calcium should be supplemented if the food is insufficient. Commercially available dairy products should be given for those with significant lactose malabsorption. Steatorrhea is also a problem and is more easily tolerated if the fat in the formula is given as medium-chain triglycerides. In conclusion, the dietary formula for patients with dumping syndrome after gastric surgery should refer to the food nutrient list. Each meal should be adjusted to suit the patient based on diet and social history.