Lilly drug saves muscle when added to Wegovy weight-loss shot

Patients who took an experimental drug from Eli Lilly and Co. together with Novo Nordisk A/S’s Wegovy maintained muscle while losing weight, offering a potential solution to one of the key problems that’s emerged with popular obesity shots.

The closely-watched study showed that patients on Wegovy combined with bimagrumab lost 22.1% of their body weight in 48 weeks, with 92.8% of that coming from the body’s fat stores, according to results shared Monday at the American Diabetes Association conference in Chicago.

Those on Wegovy alone lost 15.7% of their weight, with 71.8% coming from body fat—indicating more muscle was lost when the experimental drug wasn’t included in the regimen.

“This is the result we were hoping for,” said study lead Louis Aronne, a physician who directs the Comprehensive Weight Control Center at Weill Cornell Medicine.

The trial was funded by Lilly, which bought bimagrumab for about $2 billion in 2023 from startup Versanis Bio. Lilly is now running additional studies of bimagrumab in combination with its own obesity shot, Zepbound.

When people drop weight quickly, whether via obesity drugs or bariatric surgery, they tend to lose muscle alongside fat. That’s raised concerns, particularly for people over 65, who take weight-loss drugs. It’s also made muscle preservation an alluring target for drugmakers like Regeneron Inc. and biotech Veru Inc., which are seeking a foothold in the fast-growing and lucrative obesity market.

Additional drug combinations may carry a risk of more side effects though, raising concerns from some doctors. Regeneron recently said that a combination of Wegovy and two other experimental drugs spurred more weight loss, while preserving muscle for patients enrolled in its trial.

However, about 28% of patients dropped out of the trial and two patients receiving the drugs died. Regeneron said it “has not identified a causal association” between the drugs and deaths. Still, Bloomberg Intelligence analysts called the result “unnerving.”