A small study presented at this year’s Endocrine Society meeting offers new insight into how weight-loss drugs like Ozempic and Wegovy may affect muscle mass, and how diet could help protect it.
These medications, known as GLP-1 receptor agonists, are commonly prescribed for people with obesity.
Researchers found that people taking semaglutide lost more total weight than those following a diet and lifestyle program, but about 40% of that weight loss came from lean mass, including muscle. That’s a concern, especially for older adults and women, who the study suggests may be more prone to muscle loss while using the drug.
The findings point to protein intake as a possible way to reduce that risk.
“Older adults and women may be more likely to lose muscle on semaglutide, but eating more protein may help protect against this,” said lead researcher Dr. Melanie Haines of Massachusetts General Hospital and Harvard Medical School.
Muscle plays a critical role in blood sugar control and bone strength. Losing too much muscle, especially during rapid weight loss, may limit the health benefits of semaglutide, particularly when it comes to improving blood sugar levels and reducing insulin resistance. In the study, people who lost more muscle saw less improvement in blood sugar.
The researchers studied 40 adults with obesity over a three-month period. Of these, 23 were prescribed semaglutide, while 17 took part in a lifestyle program called Healthy Habits for Life. Although both groups lost muscle as part of their weight loss, the data showed that within the semaglutide group, those who ate more protein lost less muscle.
“Preserving muscle during weight loss with semaglutide may be important to reduce insulin resistance and prevent frailty in people with obesity,” Haines said.
The study is small and still in early stages. More research is needed to understand how best to support muscle health while taking GLP-1 medications like semaglutide. But the findings highlight the value of nutrition, especially protein quality and timing, as part of any weight-loss strategy.
This research was presented at ENDO 2025, the Endocrine Society’s annual meeting. It was not yet published in a peer-reviewed journal at the time of presentation.