Diet after gastrectomy for weight loss is one of the most important concerns of patients. Patients cannot control their own diet after gastrectomy because vomiting will occur if they eat too much after surgery, especially within 3 weeks after the surgery, the diet should be mainly liquid, for example, patients should be discharged from hospital in about 1 week, and the diet should be mainly liquid, such as water, rice soup, milk, soybean milk, fish soup, meat soup, vegetable soup and other food without slag. Patients should be on a liquid diet for 3 weeks, and can gradually transition from a liquid diet to a semi-liquid diet for more than 3 weeks. The semi-liquid diet includes thin rice, noodles, egg custard, steamed eggs and other better digested foods. After 1-2 months of this type of diet, there is a gradual transition to soft foods. In addition, there will be an appropriate dietitian to guide the patient’s diet. And does the skin sag after gastrectomy bariatric surgery? First of all, obesity is measured according to the body mass index, or BMI, and can be classified as mild, moderate or severe according to the degree. The BMI of the Asian population is more than 37.5, that is, it is severe obesity. Patients with severe obesity have a large body surface area, and after undergoing surgery to slim down, the skin on the body surface will not shrink with weight, and the skin will be sagging. Patients with moderate obesity and mild obesity will not have obvious skin laxity after surgery, and serious skin laxity is called bat sleeve, as loose as the skin of a bat. Patients over 400 pounds are likely to have skin laxity after surgery, but patients between 200-300 pounds usually do not have skin laxity after surgery.