Also known as Mounjaro in its approved type 2 diabetes indication, tirzepatide helped participants across two trials—SURMOUNT-3 and SURMOUNT-4—lose up to 26.6% of their body weight, Lilly said Thursday. Tirzepatide met all primary endpoints across both trials, Lilly said.

SURMOUNT-3 pitted tirzepatide against placebo in obese or overweight adults over a 72-week span following a 12-week intensive lifestyle intervention lead-in period. That intervention included a low-calorie diet, exercise and weekly counseling sessions, Lilly explained in a press release.

To qualify for Lilly’s trial, participants had to lose at least 5% of their body weight by the end of the 12-week lead-in.

In SURMOUNT-3, those on tirzepatide lost an additional 21.1% of their body weight from randomization, while patients on placebo experienced an average weight regain of 3.3% over 72 weeks, Lilly said.

SURMOUNT-4, meanwhile, looked at tirzepatide’s safety and efficacy over 52 weeks after a 36-week open-label tirzepatide lead-in period, during which all study participants received Lilly’s drug.

In the SURMOUNT-4 lead-in period, participants lost an average of 21.1% of their body weight, Lilly said. Those who stayed on tirzepatide lost an additional 6.7% of their body weight during the trial.

Over that same stretch, patients on placebo regained an average of 14.8% of their body weight.