Eli Lilly said its experimental retatrutide shot delivered weight loss of 19% to 28% across three doses in a late-stage study of people with obesity, with some results comparable to weight-loss surgery—while the company weighs future FDA approval.
A late-stage study result landed with force on May 21: Eli Lilly said its experimental weight-loss medicine. retatrutide. produced weight loss that—in some cases—rivaled bariatric surgery. Now the company is pushing for the next step. even as the science is still awaiting peer review and regulatory review.
Lilly said in a news release Thursday that people taking retatrutide across three different dosages achieved weight loss ranging from 19% to 28%. The company reported that results for some participants were on par with weight-loss surgery. a comparison that could matter immensely in a market where access. side effects. and durability of results are all closely watched.
The company’s numbers were stark. Participants taking a 9 mg dose lost an average of 64 pounds, or nearly 26% of their body weight. Those taking a higher 12 mg dose lost an average of 70 pounds, or more than 28% of their body weight. For a smaller 4 mg dose group, participants lost an average of 47 pounds, or about 19% of their body weight.
Lilly also said weight reduction was common among the highest-dose participants over the study period. Nearly 2 in 3 people taking the 12 mg dose over 80 weeks lost enough weight to fall below the obesity measure based on a person’s height and weight. Nearly half of the people on the 12 mg dose lost an average of more than 30% of their body weight—also described by Lilly as a result on par with weight-loss surgery.
The road to any real-world impact still runs through regulators and clinicians. Lilly reported the results in a news release. meaning the study results have not been peer reviewed or published in a scientific journal. The company has not yet filed for Food and Drug Administration approval, but it could do so this year.
The study comes as the broader weight-loss drug market keeps expanding. If retatrutide is approved, it would join Lilly’s existing anti-obesity medications Zepbound and the weight-loss pill Foundayo. Novo Nordisk markets Wegovy. available as an injectable and once-a-day pill—already showing how quickly consumers are moving from “promising” to “available.”.
There are also practical considerations, especially for patients deciding whether the trade-off is worth it. Lilly said the most common side effects among study participants included nausea, constipation, vomiting and upper respiratory tract infection.
What sets retatrutide apart, Lilly said, is its hormonal targeting. The medication works differently than existing treatments because it includes GIP, GLP-1 and glucagon triple hormone receptor agonists. By contrast. other available medications often referred to as GLP-1s mimic the effects of glucagon-like peptide-1. a hormone that regulates metabolism.
The sequence of facts matters: Lilly described rapid and large weight losses across 9 mg. 12 mg and 4 mg doses. linked those outcomes to obesity thresholds and surgery-level benchmarks. and then paired the claims with clear limits—no peer review yet and no FDA filing yet. The tension for the market is straightforward: the results are compelling. but the timeline for access depends on steps that haven’t happened yet.
Eli Lilly retatrutide weight loss shot obesity drug FDA approval late-stage study GLP-1s Zepbound Wegovy GIP GLP-1 glucagon