The recent introduction of the new generation of anti-obesity medications (AOMs) will change the future of obesity treatment. These highly effective medications, such as high-dose semaglutide and tirzepatide, are hormone analogues that augment the incretin function and exert multiple physiological effects by activating glucagon-like peptide-1 (GLP-1) and/or glucose-dependent insulinotropic polypeptide (GIP) distributed in various organs. These medications provide an average of 15-22% weight reduction in one-year trials, which had not been seen in the past with medical therapy. While the literature suggests that bariatric surgery is superior to these new highly effective medications, there is no head-to-head comparison between the most common bariatric operations (Roux-en-Y gastric bypass \[RYGB\] and sleeve gastrectomy \[SG\]) with semaglutide (once weekly) and tirzepatide (once weekly). The goal of this Randomized Clinical Trial (RCT) is to compare these effective therapies in patients with severe obesity to provide the best evidence to inform clinical decisions in treating patients with obesity.

This is a randomized, non-blinded, controlled efficacy/safety study with 3 parallel groups who will either receive bariatric surgery (RYGB or SG), semaglutide, or tirzepatide. The study has 2 phases: the first 12 months for the assessment of the primary endpoint ( mean percentage weight loss) and the second 12 months as the extension phase of the study to mimic the real-life setting. Findings at the end of each phase will be separately reported. A randomized trial of 125 patients with a BMI of 35-65 kg/m2 who sought treatment for obesity at Cleveland Clinic will be performed. Patients who meet the ASMBS/IFSO 2022 guidelines for bariatric surgery will be invited for possible enrollment. Interested and eligible patients will be randomized to receive their already chosen bariatric surgery (RYGB or SG), tirzepatide. or semaglutide in 2:2:1 ratio. The study is not intended to compare RYGB vs SG head-to-head. RYGB and SG constitute one group as a bariatric surgery group. The assignment of RYGB or SG is not based on a randomized design. Each patient and surgical team will make a shared decision about the most appropriate surgical procedure. The study is also not intended to compare semaglutide vs tirzepatide head-to-head. In the second or extension phase of the study, participants are followed from month 12 to month 24, regardless of the treatment that they receive. In this phase, the study medications (semaglutide and tirzepatide) will not be provided by the study. The goal of this phase is to provide valuable insights into A) access to AOMs and the durability of effects in the real-life setting, B) cross-over from AOMs to bariatric surgery, and C) adjuvant pharmacotherapy after bariatric surgery.