Eli Lilly experimental obesity drug could beat rivals in total weight loss for patients

Eli Lilly’s experimental drug helped patients lose up to 24% of their weight after almost a year, the highest reduction seen in the obesity treatment space to date, according to new mid-stage clinical trial results released Monday. 

The phase two trial followed 338 adults who were obese or overweight and either received the pharmaceutical company’s injection, retatrutide, or a placebo each week. 

Patients who took a 12-milligram dose of retatrutide lost 17.5% of their body weight, or 41 pounds, on average after 24 weeks, compared with 1.6% for those who received the placebo. 

Patients lost 24.2%, or 58 pounds, on average after 48 weeks. Those who took the placebo lost 2.1% of their body weight after that same time period.

The trial's researchers said average weight loss did not appear to plateau after 48 weeks, suggesting a longer study could show even more. Eli Lilly is currently recruiting patients for a phase three trial.

That data suggests Eli Lilly’s retatrutide is the “most effective anti-obesity med to date,” Michael Weintraub, an endocrinologist at NYU Langone Health, said in a Twitter post. 

Eli Lilly’s other obesity drug Mounjaro, which is approved for type 2 diabetes, has helped patients lose up to 21% of their weight in clinical trials.

Novo Nordisk’s Wegovy, cleared for weight loss, has shown up to 15% weight loss in trials. 

Like Wegovy and Mounjaro, Eli Lilly's retatrutide is a weekly injection that changes the way patients eat and leads to decreased appetite by mimicking certain hormones in the gut.

But Wegovy only mimics one hunger-regulating hormone called GLP-1, while Mounjaro mimics GLP-1 and another hormone called GIP.

Retatrutide mimics three different hunger-regulating hormones: GLP-1, GIP and glucagon. That appears to have more potent effects on a person's appetite and satisfaction with food.