Objectives To quantify and compare the rate of weight regain after cessation of weight management medications (WMMs) in adults with overweight or obesity. Design Systematic review and meta-analysis. Study selection Trial registries and databases (Medline, Embase, PsycINFO, CINAHL, Cochrane, Web of Science, and trial registries) were searched from inception until February 2025 for randomised controlled trials (RCTs), non-randomised trials, and observational studies that included WMM (≥8 weeks) with follow-up for ≥4 weeks after cessation of treatment in adults with overweight or obesity. Comparators were any non-drug weight loss intervention or placebo. Data extraction and synthesis The review followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Two independent reviewers screened titles, extracted data, and assessed the risk of bias using the Cochrane Risk of Bias 2 tool for RCTs and the ROBINS-I tool for non-randomised trials. Data were analysed using mixed effect, meta-regression, and time-to-event models. Weight regain after cessation of WMM was compared with that reported after cessation of behavioural weight management programmes (BWMPs). Main outcome measures The primary outcome was rate of weight regain from end of treatment, with associated changes in cardiometabolic markers as a secondary outcome. Results Of the 9288 titles screened, 37 studies (63 intervention arms, 9341 participants) were included. Average treatment duration was 39 (range 11-176) weeks, with average follow-up of 32 (4-104) weeks. The average monthly rate of weight regain was 0.4 kg (95% confidence interval (CI) 0.3 to 0.5) (mixed model 0.3 kg (0.2 to 0.4) monthly v control in RCTs). All cardiometabolic markers were projected to return to baseline within 1.4 years after the cessation of WMM. Weight regain was faster after WMM than after BWMP (by 0.3 kg (0.22 to 0.34) monthly), independent of initial weight loss. Estimates and precision were robust in sensitivity analyses. Conclusions This review found that cessation of WMM is followed by rapid weight regain and reversal of beneficial effects on cardiometabolic markers. Regain after WMM was faster than after BWMP. These findings suggest caution in short term use of these drugs without a more comprehensive approach to weight management. Systematic review registration PROSPERO CRD42024532069. Data may be made available to investigators upon request by email to the corresponding author.