Bariatric surgery is a type of surgery used to treat obesity, mainly gastric banding, sleeve gastrectomy, gastric diversion, etc. Different surgical methods have different side effects, such as band slippage, intestinal obstruction, anastomotic fistula and anesthesia accidents. 1. Gastric banding: After the operation, it may cause nausea, vomiting, slippage of band, intestinal obstruction, residual gastritis and other side effects. Moreover, gastric band is a foreign implant, which has a complicated structure and may malfunction, and some patients may also have symptoms such as rejection reaction and infection. 2. Sleeve Gastrectomy: The operation usually requires the use of anastomosis to reduce the volume of most of the stomach, so the anastomosis may not heal well, and part of the stomach needs to be removed during the operation, and after the operation, the stomach’s function of storing and digesting food may be reduced. 3. Gastric diversion: side effects such as anastomotic rupture, anastomotic fistula, anastomotic obstruction, and gastric emptying obstruction may occur after the surgery. In addition, no matter what kind of weight loss surgery is performed, there may be anesthesia accidents during the operation, such as aspiration and reflux, cardiac arrest and so on. Patients who need to undergo weight loss surgery should choose regular hospitals and professional doctors, which can reduce the risk of surgery to a certain extent.