Eli Lilly’s latest clinical trial data reveal that its experimental drug, retatrutide, could be a significant leap forward in obesity treatment. The phase 3 results suggest it may outperform existing weight loss medications like semaglutide (Wegovy) and tirzepatide (Zepbound), though approval is still pending.
How Retatrutide Works Differently
Retatrutide is a “triple agonist,” activating three key hormone receptors involved in appetite and metabolism: GLP-1, GIP, and the glucagon receptor. This contrasts with current drugs: Ozempic and Wegovy target only GLP-1, while Zepbound and Mounjaro work on both GIP and GLP-1. By hitting three receptors, retatrutide may offer greater efficacy.
Trial Results: Significant Weight and Pain Reduction
A trial involving over 400 obese participants with knee osteoarthritis showed remarkable results. Those taking a 9mg or 12mg weekly dose of retatrutide lost up to 28.7% of their body weight (an average of 71.2 pounds) over 68 weeks. Additionally, knee pain decreased by an average of 4.5 points, representing a 75.8% reduction.
For context, a New England Journal of Medicine study comparing tirzepatide and semaglutide showed tirzepatide led to an average weight loss of 50 pounds (20.2% of body weight) over the same period. Semaglutide resulted in an average loss of 33 pounds (13.7%).
Expert Perspectives: A Potential Breakthrough with Caveats
Medical experts are cautiously optimistic. “It doesn’t hurt to have other alternatives,” says Mir Ali, MD, medical director of MemorialCare Surgical Weight Loss Center. Gitanjali Srivastava, MD, co-director of Vanderbilt Weight Loss Clinics, calls the results “remarkable” and highlights retatrutide as a “potential breakthrough therapy.”
However, both doctors emphasize the need for further research. Side effects, common to these medications, include nausea, diarrhea, constipation, and vomiting. Long-term effects remain unknown. Moreover, sustained weight loss requires lifestyle changes alongside medication. As Dr. Ali notes, “patients commonly regain weight when they stop these medications.”
The Bigger Picture: A Growing Market for Obesity Drugs
The development of retatrutide underscores the rapidly evolving landscape of obesity treatment. The success of drugs like Wegovy and Zepbound has driven demand for more effective options. Retatrutide’s triple-agonist approach may represent the next step in this trend, but its ultimate impact will depend on FDA approval and long-term data.
The race to develop more potent weight loss drugs is accelerating as obesity rates climb globally. These medications, while promising, are not a silver bullet and require ongoing commitment from patients to maintain results.
