Effects of Dietary Self-Monitoring, Physical Activity, Liraglutide 3.0 mg, and Placebo on Weight Loss in the SCALE IBT Trial

Introduction: Individuals who enroll in intensive behavioral therapy (IBT) programs are asked to make several lifestyle changes simultaneously. However, few studies have examined the relative effects of adherence to different treatment components on weight loss. Objective: This secondary analysis of the SCALE IBT trial assessed adherence to the medication regimen, dietary self-monitoring, and physical activity recommendations and their relative contributions to weight change in individuals with obesity who were provided with IBT combined with either liraglutide 3.0 mg or placebo. Methods: SCALE IBT was a double-blinded, multicenter, randomized controlled trial comparing 56-week weight losses in individuals with obesity who received liraglutide 3.0 mg (n = 142) or placebo (n = 140), as an adjunct to IBT. Adherence to dietary self-monitoring, physical activity, and medication usage (liraglutide or placebo) were measured during the 56-week treatment period. A regression model was used to estimate the relative contribution of adherence to each treatment component to weight loss at week 56. Results: The proportion of individuals who adhered to each intervention component decreased over time. Compared with non-adherence, complete adherence to dietary self-monitoring and physical activity recommendations were associated with estimated weight changes of −7.2% (95% CI –10.4 to –4.0; p < 0.0001) and –2.0% (95% CI –3.2 to –0.8; p = 0.0009), respectively. Complete adherence to liraglutide predicted an additional weight loss of –6.5% (95% CI –10.2 to –2.9; p = 0.0005) relative to individuals who did not adhere to the medication regimen, while adherence to placebo did not have a statistically significant effect on weight loss (p = 0.33). Conclusions: High adherence to dietary self-monitoring and use of liraglutide 3.0 mg was associated with clinically relevant weight loss with IBT and adjunctive pharmacotherapy. The effect of adherence to physical activity was significant but smaller.