As anyone who knows anything about bariatric surgery knows, there are several types of bariatric surgery, the main effect of which is to limit the amount of food intake and nutrient absorption. As in the case of gastric bypass surgery, the goal of weight loss is to reduce the amount of nutrients absorbed by the intestines from food by reconstructing the digestive tract. The gastric reduction surgery mainly lies in the changes in the stomach and does not make adjustments in the intestine, so how does the surgery achieve the reduction of nutrient absorption? The stomach has the function of storing food, digesting and absorbing, and secreting hormones, etc. When two-thirds of the stomach is removed by gastric reduction surgery, the obvious physical change is that the stomach shrinks, but at the same time, the various hormones secreted by the stomach are also reduced, and the corresponding function is also weakened. In addition, in order to achieve a better reduction in nutrient absorption, many doctors will add a secondary procedure, or sleeve gastrojejunostomy, for patients according to their specific body conditions. In the current domestic bariatric surgery environment, the number of cases of gastric reduction surgery exceeds that of other procedures, mainly because of the relatively low operational difficulty of gastric reduction surgery, while in special cases, such as the above-mentioned surgery that requires additional jejunostomy, many doctors are unable to do so.