Phase 3 trial reports 25% average weight loss with highest retatrutide dose

Weight reductions compared across doses after 80 weeks

According to the report, 2,339 adults with obesity but without diabetes were randomly assigned weekly retatrutide at 4, 9, or 12 milligrams, or placebo. Average weight reductions after 80 weeks were reported as 17.6%, 23.7%, and 25% across the three doses, versus 3.9% with placebo.

In subgroups, knee-pain scores and obstructive sleep-apnea breathing events declined more with the highest dose than with placebo. Retatrutide remains experimental.

Earlier phase 2 results described average 24.2% weight loss after 48 weeks at the highest dose. The reported phase 3 trial used a larger group and followed outcomes for 80 weeks; the two-year extension involved only participants who entered it.

The report describes dose-dependent average weight loss after 80 weeks, reaching 25% in the 12-milligram group, alongside greater reductions than placebo in knee pain and sleep-apnea events among the relevant subgroups.

Side effects and questions outside the trial’s scope

The reported trial assessed obesity alongside knee osteoarthritis pain and obstructive sleep apnea, rather than weight alone. It also reported side effects: nausea was reported by about 42% of the highest-dose group, and adverse events led about 11% to stop treatment. The study was not designed to establish cardiovascular safety or directly compare retatrutide with semaglutide or tirzepatide.