The first big real-world comparison finds more weight loss on tirzepatide
A large real-world study found people taking tirzepatide (Mounjaro) were about three times more likely to lose 15% of their body weight than those on semaglutide (Ozempic), though it wasn't a randomized trial.
A new analysis of electronic health records has found that patients taking tirzepatide, the active ingredient in Mounjaro and Zepbound, lost more weight and lost it faster than patients taking semaglutide, the active ingredient in Ozempic and Wegovy [1][2]. The study, released November 27, 2023 by Truveta Research, looked at records for more than 18,000 adults [2] and found that people on tirzepatide were about three times more likely to reach 15% weight loss than people on semaglutide [1][2].
The research compared 9,193 patients on Mounjaro with a closely matched group of 9,193 patients on Ozempic, all of whom started treatment between May 2022 and September 2023 [1][2]. About half the group had type 2 diabetes [1][2]. After one year, 42.3% of tirzepatide patients had lost at least 15% of their body weight, compared with 19.3% of semaglutide patients [1]. After adjusting for individual risk factors, tirzepatide patients were 76% more likely to lose at least 5% of body weight, more than twice as likely to lose at least 10%, and more than three times as likely to lose at least 15%, compared with semaglutide patients [1].
The gap in average weight loss widened over time. At three months, tirzepatide patients had lost 5.9% of body weight versus 3.6% for semaglutide patients [2]. By six months, the numbers were 10.1% versus 5.9% [2]. By one year, tirzepatide patients had lost 15.2% of body weight compared with 7.9% for semaglutide patients [2], a gap the Reuters report also framed as a 7.2 percentage point difference at 12 months [1]. Rates of gastrointestinal side effects were similar between the two groups [1][2].
Both drugmakers pushed back on how the study should be read. A Novo Nordisk spokesperson noted that the semaglutide doses studied have not been evaluated for chronic weight management, and that there are no completed head-to-head trials comparing Wegovy and tirzepatide directly [1][2]. Novo also pointed out that Ozempic is dosed lower than Wegovy, while Mounjaro and Zepbound share the same dosing [2]. An Eli Lilly spokesperson said the company does not promote off-label use of its medicines and that it did not sponsor the study [1][2]. The study itself, posted on medRxiv, carries a notice that it has not been peer-reviewed and
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