A new study has found that older adults and women who take the weight-loss drug semaglutide may lose more muscle than others.
But eating more protein might help lower this risk. The findings were presented at ENDO 2025, the Endocrine Society’s yearly meeting in San Francisco.
Semaglutide is a medicine that helps people lose weight by making them feel full and slowing down digestion. It copies a natural hormone in the body called GLP-1. It’s often used by people with obesity and type 2 diabetes.
While it’s effective at helping people lose weight, it can also cause people to lose muscle, not just fat. Muscle loss during weight loss is known as lean mass loss.
Dr. Melanie Haines, the main researcher from Massachusetts General Hospital and Harvard Medical School, explained that losing muscle is not good for health. Muscles help control blood sugar and keep bones strong. Losing too much muscle can make your metabolism slower, weaken your bones, and increase the risk of frailty, especially as you age.
The researchers studied 40 adults with obesity for three months. Out of the group, 23 people were given semaglutide, and the other 17 followed a healthy lifestyle and diet program called Healthy Habits for Life (HHL). The team measured how much muscle participants lost while losing weight.
People who took semaglutide lost more total weight than those who followed the diet plan. But in both groups, about 40% of the weight lost came from muscle, not fat. This shows that muscle loss happens no matter how people lose weight—whether it’s through medicine or lifestyle changes.
The study also found that muscle loss was worse in some people. In the semaglutide group, older adults, women, and people who ate less protein lost more muscle.
And the people who lost more muscle didn’t see as much improvement in their blood sugar levels. This was measured using a marker called HbA1c, which shows how well blood sugar is controlled over time.
This is important because one of the main goals of using semaglutide is to help manage type 2 diabetes. If too much muscle is lost, it may reduce the drug’s ability to improve blood sugar levels. That’s why it’s important to find ways to protect muscle during treatment.
Dr. Haines said that eating more protein could help keep muscle while using semaglutide. This could help people get the benefits of weight loss—like better blood sugar—without the downside of muscle loss.
She also said that more research is needed. Scientists want to find the best ways to help people lose fat but keep muscle when using drugs like semaglutide. This is especially important for women and older adults, who seem more likely to lose muscle during treatment.
If you care about muscle, please read studies about factors that can cause muscle weakness in older people, and scientists find a way to reverse high blood sugar and muscle loss.
For more health information, please see recent studies about an easy, cheap way to maintain muscles, and results showing these vegetables essential for your muscle strength.
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