Retatrutide weight-loss drug shows 28% body weight

Indianapolis, 21 May 2026 Eli Lilly's experimental weight-loss drug Retatrutide helped obese patients lose over 28% of their body weight on average over 80 weeks in a Phase-III clinical trial, the company announced Thursday. Participants taking the highest dose of 12 mg of Retatrutide lost an average of 28.3% of their weight, with over 45% losing 30% or more. Those taking a lower dose of 4 mg lost 19% of their weight over the same period. The results significantly outperform previous weight-loss drugs like Zepbound from Eli Lilly and Wegovy from Novo Nordisk, which achieved 15-20% weight loss in studies. Kenneth Custer, head of cardiometabolic health at Eli Lilly, stated that the weight loss achieved with Retatrutide is comparable to that from bariatric surgery. "Das ist ein Gewichtsverlust in einem Ausmaß, wie er bisher mit der Adipositas-Chirurgie in Verbindung gebracht wurde" (This is weight loss on a scale previously associated with bariatric surgery), he said. Retatrutide is the first Eli Lilly drug that activates three hormone receptors simultaneously to curb appetite, promote insulin secretion, and support fat burning. This triple action is likely the key to its effectiveness. ## How Retatrutide Works Graham Finlayson, a professor of psychobiology at the University of Leeds, noted that the activation of three hormone receptors is likely the key difference in Retatrutide's effectiveness compared to previous medications. Simon Cord, a professor of physiology at Anglia Ruskin University, expressed confidence in the robustness of the results from previous studies on Retatrutide. He welcomed the development of effective and safe medications for treating obesity, noting that it is a lifelong condition requiring active medical treatment. About 12.5% of participants taking the highest dose experienced skin sensations (dysesthesia) as a side effect, down from 20.9% in earlier studies. Approximately 11% of participants discontinued treatment due to adverse side effects. ## Side Effects and Discontinuation Rates The analysts at RBC Capital Markets had anticipated weight loss of 28-30%, meaning the current results align with expectations. The drug's performance suggests it could become a leading treatment for obesity if approved. Eli Lilly plans to submit Retatrutide for regulatory approval following the successful Phase-III trial results. The drug represents a significant advancement in pharmacological weight-loss treatments. Obesity affects millions worldwide and is associated with numerous health risks, including diabetes and heart disease. Effective treatments like Retatrutide could help address this growing public health concern. ## Broader Implications for Obesity Treatment While the results are promising, experts caution that lifestyle changes remain an essential component of weight management. Medications like Retatrutide are most effective when combined with diet and exercise. The development of Retatrutide highlights the pharmaceutical industry's ongoing efforts to combat obesity with innovative treatments. As research progresses, more effective and safer options may become available to patients.

Eli Lilly's Experimental Drug Retatrutide Shows Promising Weight Loss Results in Clinical Trial

How Retatrutide Works

Side Effects and Discontinuation Rates

Broader Implications for Obesity Treatment