The Effect of Antidepressant Use on Weight Loss After One Anastomosis Gastric Bypass: A Retrospective Cohort Study

Objective: Antidepressant use is frequently associated with weight gain, yet little is known about its impact on postoperative weight loss following bariatric surgery. This study aimed to examine how antidepressant use—before and/or after surgery—affects weight loss outcomes in patients undergoing one-anastomosis gastric bypass (OAGB). Material and Method: This retrospective cohort study included 181 patients who underwent OAGB between January 2020 and December 2021. Based on antidepressant use, patients were categorized into four groups: no use (n=87), preoperative use only (n=25), continued use before and after surgery (n=36), and new initiation after surgery (n=33). Weight loss outcomes were assessed using percentage of excess BMI loss (%EBMIL) and total weight loss (%TWL) at 12 months postoperatively. Statistical comparisons were conducted using independent samples t-tests. Results: There were no significant differences in %TWL between any of the groups (range: 34.54%–37.05%). However, %EBMIL was significantly lower in the continued-use group (82.21%) compared to the no-use group (p=0.0270) and the preoperative-use-only group (p=0.0196). No statistically significant differences were found between other groups. Demographic variables were generally comparable, though hypertension, hyperlipidemia, and gender distribution differed significantly across groups. Conclusion: Continued antidepressant use after OAGB may negatively affect %EBMIL, despite similar %TWL outcomes. These findings suggest that antidepressant exposure, particularly when continued into the postoperative period, may attenuate the optimal metabolic benefits of bariatric surgery. Future prospective studies with pharmacokinetic monitoring and larger samples are warranted to clarify medication-specific effects.