Eli Lilly said ‌on Thursday that its experimental drug retatrutide helped patients diagnosed with obesity lose more ​than 28% of their weight over a year and a half in a key ⁠trial that helps pave the way for the firm to seek regulatory approval and launch the drug next year. Shares of Lilly climbed 1% in premarket trading. The late-stage trial, which tracked weight loss in patients diagnosed with ‌obesity but not diabetes, marks the latest leg of Lilly’s push to dominate the booming market for obesity medications, such as its injectable Zepbound and Novo Nordisk’s Wegovy.

This is ‌Lilly’s most powerful weight loss drug yet, and is meant to appeal to those who ‌need ⁠to lose the most weight. Its Zepbound and Novo’s Wegovy have shown weight ⁠loss in trials of around 15-20%, while its oral pill has shown weight loss of around 11%. Retatrutide is the first of Lilly’s obesity drugs that activates three hormone receptors - GLP-1 to suppress appetite, GIP to enhance insulin secretion and glucagon to aid ​fat burning - earning it the nickname “triple G”. ‌In previous trials, it has been shown to boost weight loss well beyond Lilly’s and its Danish rival’s other drugs.

In this late-stage trial for adults with obesity or who were overweight and at least one weight-related comorbidity, the firm found patients on the highest dose, 12 milligrams, of retatrutide ‌lost an average of 28.3% of their weight over 80 weeks. More than 45% ​of participants lost 30% or more.

“That’s really a threshold that’s historically been associated with bariatric surgery,” Kenneth Custer, Eli Lilly’s president of cardiometabolic health, said in an ⁠interview. “To have that available in a medicine is a pretty big deal.”

Custer said the company hopes to launch the drug next year. Investors are keenly focused on safety and other side effects of weight-loss ‌drugs in development. In the late-stage trial, incidents of dysesthesia, an abnormal skin sensation, occurred in 12.5% of patients treated with the 12 mg dose, compared with 20.9% of patients on the highest dose in the December trial result. About 11% of patients on the top dose discontinued due to adverse events. The results appear to be in line with expectations. RBC Capital Markets analysts said in a note on Tuesday that they were expecting 28% to 30% weight loss from the trial.

Patients with qualifying ‌body mass index extended use of the drug for a full two years and lost an average of just ​over 30%, the company said.

Participants on a smaller, 4-milligram dose lost 19% of their weight over 80 weeks, Lilly said. In a previous trial published in December, retatrutide ⁠helped patients with obesity and osteoarthritis of the knee lose an average of 28.7% of their weight over 40 ⁠weeks and reduce knee pain. In March, Lilly said another trial showed the drug helped reduce blood sugar levels and lose an average of 15.3% of their weight. Previously, J.P. Morgan ‌analysts have said the incidences of side effects with retatrutide were higher than seen with Lilly’s other diabetes drug, Mounjaro, which partially offset the efficacy.

When asked about side effects, Custer said ​the drug was on par with other GLP-1 medications.

Published on May 21, 2026