Sleeve gastrectomy (SG) has become the most commonly performed weight loss surgery, accounting for 60% of all bariatric operations worldwide. While technically easier with less side-effects and nutritional risks than other operations, SG is also associated with a higher risk of failure (20 to 40%). In such case, the most effective option consists in adding an intestinal bypass called the Biliopancreatic Diversion with Duodenal Switch (BPD-DS). This surgery is, however, technically challenging and yields a significant risk of complications, nutritional deficiencies or gastro-intestinal side-effects. Recently, a simplified version of the Standard DS, called Single-Anastomosis Duodenoileal Switch (SADI-S) was endorsed by surgical societies as one of the approved bariatric procedures. There is currently no prospective or randomized data to support the effectiveness of this new procedure, especially as a revisional approach. The Overall Objective of this randomized controlled trial project is to establish the clinical benefits of the SADI-S as a revisional surgery after SG, while also considering critical issues related to sex and gender. The investigator Overall Hypothesis is that the SADI-S represents a relevant revisional option for weight loss and metabolic recovery in women and men suffering from severe obesity who had a previous SG. The investigator propose to address the following research question. Research Question: What are the clinical effects of SADI-S compared to standard DS when used as a revisional procedure after SG, in patients with obesity? Participants who need revisional surgery after SG will be enrolled in a prospective, randomized, double-blind (patient-evaluator), non-inferiority trial comparing SADI-S vs DS. The primary outcome will be 12-month excess weight loss. Secondary outcomes will be perioperative complications, risk of malnutrition, quality of life and gastrointestinal side effects. The investigator hypothesize that SADI-S offers similar weight loss compared to standard DS, but a lower risk of complications and nutritional deficiencies. With the increase in the number of bariatric operations performed worldwide and the recent endorsement of the SADI-S as a regular procedure, reliable clinical data are urgently needed. The present proposal will directly address this knowledge gap.