Shedding Fat, Not Muscle Is Lilly’s Next Weight-Loss Target (2)

Eli Lilly & Co. will study its blockbuster diabetes drug Mounjaro in combination with an experimental muscle-loss treatment as it searches for ways to help patients maintain muscle while losing weight.

The sheer amount of weight patients are shedding from Mounjaro and similar GLP-1 medications has raised concern that it isn’t just fat melting away, but potentially vital muscle and bone that play key roles in regulating metabolism and preventing injury, particularly in older adults.

Lilly fell as much as 3.4% as of 12:31 p.m. in New York, its biggest intraday loss since Sept. 22.

Mounjaro is still under ...