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# Lilly Says Retatrutide Delivered Up to 30% Weight Loss
- URL: https://www.fdaweb.com/lilly-says-retatrutide-delivered-up-to-30-weight-loss/
- Published: 2026-05-21T12:00:00.000Z
- Updated: 2026-09-14T13:39:40.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5161189

Eli Lilly says its investigational obesity drug retatrutide produced weight-loss results approaching those historically associated with bariatric surgery in a pivotal Phase 3 clinical trial, strengthening the company’s position in the increasingly competitive obesity treatment market. The drug met all primary and key secondary endpoints in the TRIUMPH-1 study, which evaluated retatrutide in overweight adults who had at least one weight-related condition, but without diabetes.

The study enrolled 2,339 participants who were randomized to receive retatrutide at 4 mg, 9 mg, 12 mg or placebo. The study lasted 80 weeks, with an additional extension phase for certain patients with severe obesity.

Participants receiving the highest 12 mg dose lost an average of 70.3 pounds, or 28.3% of body weight, after 80 weeks of treatment, Lilly says, adding that 45.3% of patients on this dose achieved at least 30% weight loss, while 27.2% lost at least 35% of their body weight. In a pre-specified extension study involving patients with a baseline body mass index of at least 35, participants continuing treatment for 104 weeks lost an average of 85 pounds, or 30.3% of body weight.

The company says all three dose levels tested in the study achieved statistically significant reductions in body weight compared with placebo. Patients receiving the lowest 4 mg dose — which required only one dose escalation step — lost an average of 47.2 pounds, or 19% of body weight, after 80 weeks.

Lilly also reports improvements in several cardiometabolic risk markers, including waist circumference, triglycerides, non-HDL cholesterol, systolic blood pressure and high-sensitivity C-reactive protein.

Side effects were generally consistent with existing incretin-based obesity therapies, Lilly says. The most common adverse events included nausea, diarrhea, constipation and vomiting, most of which were mild to moderate in severity. Discontinuation rates due to adverse events increased with dose level, reaching 11.3% in the 12 mg group, compared with 4.9% for placebo.

Retatrutide is a once-weekly injectable therapy that simultaneously targets glucose-dependent insulinotropic polypeptide, glucagon-like peptide-1 (GLP-1), and glucagon receptors. The so-called “triple agonist” mechanism is viewed as a next-generation approach beyond currently marketed GLP-1-based obesity therapies.

The company notes that additional data from the TRIUMPH program are expected later this year, including studies evaluating retatrutide in obesity patients with Type 2 diabetes and cardiovascular disease.