Roux-en-Y gastric bypass (RY-GBP) is one of the surgical techniques most widely used for the treatment of obesity. Long series of operated patients published in the literature have demonstrated its safety and efficacy. It consists on the reduction of the size of the stomach and joining it (anastomosis) with the small bowel to reduce the absorption of calories. Single anastomosis duodenoileal with sleeve gastrectomy is an increasingly used surgical technique that is a simplification of the duodenal switch. It consists on the reduction of the stomach to a tube (sleeve gastrectomy) and an anastomosis between the duodenum and the small bowel. It has been demonstrated as a effective technique and it is supported by the international scientific societies. There are no data that indicate a superiority of one technique over the other. The objective of this study is to analyze if there are differences between the two techniques in terms of postoperative weight control and gastroesophageal reflux at short, medium and long term.