Greater early weight loss after metabolic/bariatric surgery predicts greater loss up to 2 years but is also associated with weight regain in the longer term.

Background: Early postoperative weight loss may help predict later outcomes, but its reliability for longer-term weight loss and regain remains unclear. We assessed whether the percentage total weight loss (%TWL) 3 months after metabolic/bariatric surgery predicted later %TWL weight change/regain. Methods: This retrospective observational cohort study included 216 patients from a prospectively pre-recruited multicentre bariatric surgery cohort who underwent sleeve gastrectomy or Roux-en-Y gastric bypass and had 3-month %TWL and at least one later outcome. Linear regression assessed associations between 3-month %TWL and later %TWL plus weight change/regain outcomes. Adjusted incremental R2 quantified the additional variance explained by 3-month %TWL. Secondary procedure-stratified, diabetes-stratified, and baseline BMI comparator analyses are reported in the Supplementary Material. Results: Greater 3-month %TWL was associated with higher 1-year and 2-year %TWL in adjusted models (both p < 0.001) but not longer-term %TWL (p = 0.078). Incremental R2 was 38.23% for 1-year, 11.75% for 2-year %TWL and 2.25% for long-term %TWL. Greater 3-month %TWL was also associated with greater recurrent weight gain from 1 to 2 years and from 1 year to long-term follow-up. In secondary analyses, findings were broadly consistent across procedure and diabetes subgroups, while 3-month %TWL explained more additional variance in 1-year %TWL than baseline BMI Conclusion: 3-month %TWL predicted 1-year and 2-year outcomes but not longer-term %TWL, supporting its value as an early marker of postoperative weight trajectory. Heterogeneity in recurrent weight stability may contribute to weaker long-term prediction and warrants further study to determine whether early weight-loss patterns can identify patients requiring closer long-term weight management support.