OBJECTIVE: To evaluate the effects of tirzepatide on body composition, appetite, and energy intake to address the potential mechanisms involved in body weight loss with tirzepatide.
RESEARCH DESIGN AND METHODS: In a secondary analysis of a randomized, double-blind, parallel-arm study, the effects of tirzepatide 15 mg (N = 45), semaglutide 1 mg (N = 44), and placebo (N = 28) on body weight and composition, appetite, and energy intake were assessed at baseline and week 28.
RESULTS: Tirzepatide treatment demonstrated significant reductions in body weight compared with placebo and semaglutide, resulting in greater fat mass reduction. Tirzepatide and semaglutide significantly reduced appetite versus placebo. Appetite scores and energy intake reductions did not differ between tirzepatide and semaglutide.
CONCLUSIONS: Differences in energy intake during ad libitum lunch were not sufficient to explain the different weight outcomes. Further evaluation is needed to assess mechanistic differences related to tirzepatide actions on 24-h energy intake, substrate utilization, and energy expenditure.