Assessment of weight change patterns following Roux en Y gastric bypass, one anastomosis gastric bypass and sleeve gastrectomy using change-point analysis

We aimed to assess the weight loss trend following Roux en Y Gastric Bypass (RYGB), One Anastomosis Gastric Bypass (OAGB), and Sleeve Gastrectomy (SG), utilizing a change-point analysis. A retrospective cohort study was conducted on 8640 patients, from 2009 to 2023. The follow-up period extended to 7 years, with a median follow-up of 3 years (interquartile range: 1.4-5). Following metabolic bariatric surgery, four weight loss phases (three change points) were observed. The primary, secondary, and tertiary phases, transitioned at 12.64-13.73 days, 4.2-4.8 months, and 11.3-13.1 months post-operation, respectively, varying based on the type of procedure. The weight loss rate decreased following each phase and plateaued after the tertiary phase. The nadir weight was achieved 11.3-13.1 months post-procedure. There was no significant difference in the %TWL between males and females, however, males achieved their nadir weight significantly earlier. Half of the maximum %TWL was achieved within the first 5 months, with the greatest reduction rate in the first 2 weeks. Our findings inform healthcare providers of the optimal timing for maximum weight loss following each surgical method and underscore the importance of close patient monitoring in the early postoperative period.