Quick Facts

• Retatrutide helped patients lose 28.3% of their weight on average over 80 weeks in Phase 3 trials
• 45% of patients achieved 30% or more weight loss, matching bariatric surgery results
• The drug targets three hormone receptors simultaneously, unlike current obesity medications

Eli Lilly announced results from late-stage trials of retatrutide, its next-generation obesity drug that delivered significantly more weight loss than existing treatments.

The highest dose of retatrutide helped 2,500 patients lose an average of 28.3% of their weight over 80 weeks. That equals about 70.3 pounds of weight loss.

Roughly 45% of patients achieved 30% or more weight loss. These results match the effectiveness of bariatric surgery, which typically produces 25% to 35% weight loss within two years.

Patients with severe obesity who continued treatment for 104 weeks lost an average of 30.3% of their weight, or about 85 pounds.

“This is the largest weight loss I’ve ever seen in any medication trial,” said Dr. Susan Spratt, an endocrinologist at Duke Health.

Retatrutide works differently than current obesity drugs. It targets three hormone receptors at once: GLP-1 to suppress appetite, GIP to enhance insulin secretion, and glucagon to help burn fat. Current drugs like Lilly’s Zepbound and Novo Nordisk’s Wegovy target fewer receptors.

In December 2024, Lilly reported that Zepbound helped patients lose 20.2% of their body weight after 72 weeks compared to 13.7% for Wegovy in a head-to-head trial.

“People with obesity and knee osteoarthritis often live with pain and restricted mobility,” said Kenneth Custer, president of Lilly Cardiometabolic Health. “We believe retatrutide could become an important option for patients with significant weight loss needs.”

The drug showed higher rates of gastrointestinal side effects, including nausea and diarrhea. About 11% of patients on the highest dose dropped out due to side effects, higher than previous obesity drug trials.

Retatrutide remains in Phase 3 clinical trials. FDA approval is expected in 2027 or 2028, with patient access likely by early 2028.

The global obesity drug market is projected to reach $150 billion by 2035. Data analytics firm GlobalData forecasts Zepbound will generate $27.2 billion in annual sales by 2030.

Read more: Eli Lilly says its next gen obesity drug is more powerful than Zepbound and Wegovy