Study wrapper · #417
Real-World Comparative Effectiveness of Tirzepatide and Semaglutide for Obesity: A Multicentered Study.
Editor's note
This is a retrospective, multicenter real-world cohort (511 US adults) directly comparing tirzepatide and semaglutide for obesity — a head-to-head question that matters because the two are so often weighed against each other. Researchers reported greater 12-month total body weight loss with tirzepatide than semaglutide (16.6% vs 13.4%), with more tirzepatide users reaching ≥15% and ≥20% loss, and a larger gap among people without diabetes. Prior obesity-medication use was associated with less weight loss in both groups, and semaglutide users reported more gastrointestinal side effects (50.7% vs 28.5%). The design caveats are important: this is observational, not randomized, so channeling by clinician or patient preference, differing dose titration, and adherence can bias a head-to-head comparison; the cohort was predominantly White and female. Directionally consistent with randomized trial data favoring tirzepatide on weight, but read the magnitude cautiously given the observational design.
Plain-language abstract
This study compared two popular weight-loss medicines — tirzepatide and semaglutide — using real-world records from 511 adults treated for obesity at several US centers between 2021 and 2024. Researchers tracked the percentage of body weight lost at 3, 6, 9 and 12 months. At one year, people on tirzepatide lost more weight on average (16.6%) than those on semaglutide (13.4%), and more tirzepatide users reached large losses of 15% or 20% of their body weight. The difference was even bigger among people without diabetes. People who had used weight-loss medicines before lost less with either drug. Semaglutide users reported stomach and gut side effects more often (about 51% versus 29%), though both drugs were generally tolerated. Because this used existing records rather than randomly assigning treatment, other differences between the groups could influence the results, and most participants were White and female. The authors call for studies in more diverse populations.