A new Ozempic rival helps patients lose fat, but keep their muscle — the holy grail for a weight-loss drug

• A new GLP-1 drug, pemvidutide, helped patients lose fat while guarding muscle, like exercise does. 
• The weekly injectable, from Altimmune, saw trial participants losing about 75% fat, and 25% muscle.
• Drugmakers Eli Lilly and Novo Nordisk are also researching how to preserve muscle mass in GLP-1 users.

It's the holy grail for a weight-loss drug. Stay strong, but lose the fat.

Drugmaker Altimmune says its new weekly injectable, called pemvidutide, saw patients losing around 75% fat, and only 25% muscle, in results of a Phase 2 clinical trial the company announced on Wednesday.

That's impressive when you compare it to existing GLP-1 drugs like Ozempic and Wegovy (semaglutide), or Mounjaro and Zepbound (tirzepatide).

On those drugs, patients can lose as much as 40% of their muscle mass. Their ratio of muscle-to-fat usually still improves, but in particularly vulnerable populations, like older adults, the rapid and significant muscle loss can be an issue. This is why doctors recommend patients on weight loss drugs do some strength training in tandem with their medication.

But Altimmune says their drug may mimic the beneficial effects of weightlifting, without making you do the work. Pemvidutide, like tirzepatide is a two-part drug that combines a GLP-1 drug with another drug in a single shot. In this case, it's boosting glucagon, a key blood-sugar-regulating hormone. While the GLP-1 reduces a person's appetite, the glucagon is thought to mimic the effects of exercise, the company says.

"There is a growing appreciation that the quality of weight loss is as important as the quantity of weight loss," Scott Harris, Altimmune's chief medical officer, said in a release. "We believe that pemvidutide, if approved, could stand out as an attractive option for weight loss and weight maintenance."

Other drugmakers are trying to solve muscle loss on drugs like Ozempic

In July, Eli Lilly, which makes Zepbound and Mounjaro, acquired Versanis. The deal was worth $1.9 billion, FierceBiotech said.

Versanis makes a monoclonal antibody called bitmagrumab, which is thought to help preserve more muscle mass, even through weight loss.

The same antibody is also being tried out in combination with semaglutide, in a worldwide Phase 2 clinical trial being run by Eli Lilly.