Do People Reduce Attempts At Lifestyle Change After Initiating Weight Loss Medication? A Review Of Trial Evidence.

Anti-obesity medications (AOMs) are used with lifestyle change support for weight management for adults with obesity. We investigated whether initiation of AOMs appeared to reduce attempted lifestyle changes. We searched for orlistat, liraglutide, semaglutide, and low-fat reducing diet (LFRD) trials in a trial register, Medline, Embase and systematic reviews from 1990 to June 2023. Weight changes in placebo groups of AOM trials with lifestyle interventions were compared to weight changes in LFRD trials. 16 orlistat, 7 liraglutide, 5 semaglutide, and 7 LFRD trials were included. Weight loss in orlistat placebo groups was 1.1kg less than LFRDs, a statistically non-significant difference, where last observation carried forward values were used for missing data in trials. Adjustment with baseline observation carried forward found 2.6kg less weight lost, a significant difference. Last observation carried forward data for orlistat trials providing completer data found a 0.2kg difference. Liraglutide placebo groups had 2.1kg less weight lost than predicted from LFRD trials. Semaglutide placebo groups had 2.0kg less weight loss. Compensatory reductions in changes to lifestyle behaviours may result following AOM initiation, but this needs to be explored further. Variability in trial design and study populations may contribute to the differences in weight change found.