The team behind new research into the impact of weight-loss drugs on muscle loss say better strategies are needed to preserve muscle mass in those taking the medication.
While GLP-1 drugs can help people to lose a significant amount of weight, concerns have been raised about the effect that the associated muscle loss can have on long-term health.
Researchers from the University of Virginia have called for more research to further the understanding of the effects of GLP-1s.
They warn that the medication doesn’t deliver improvements in heart and lung function that is vital for long-term health outcomes.
Zhenqi Liu, Professor of Medicine and James M. Moss Professor of Diabetes at the University of Virginia School of Medicine, said: “Some patients literally told me that they felt that they were losing muscle or muscle was slipping away from them while they were on these medications.
“This is a serious concern. Muscle, especially axial muscle, is essential for posture, physical function and overall well-being. Losing lean body mass can increase the risk of cardiovascular disease, all-cause mortality and diminished quality of life.
“We need to make sure that patients prescribed these medications aren’t already at risk for malnutrition or low muscle mass.”
GLP-1 drugs can help improve blood-sugar control and bring short-term cardiorenal benefits for people with obesity, type 2 diabetes and heart failure, helping to improve survival rates.
However, to help people on GLP-1s get the longer term full cardiorespiratory benefits that come with significant weight loss, researchers say these patients may also need nutrition supplements, complementary medications or exercise programmes.
The weight lost through GLP-1 use includes the loss of fat-free mass, of which muscle makes up 40% to 50%. Up to 40% of the total weight lost can be fat-free mass, compared to age-related decline in fat-free mass which is only 8% per decade.
Professor Liu and his colleagues examined available data on the effects of GLP-1s on cardiorespiratory fitness (CRF).
Siddhartha Angadi, a cardiovascular exercise physiologist at the university, explained: “In a recent study by our group that examined mortality outcomes from almost 400,000 individuals across the world, we found that CRF was far superior to overweight or obesity status for predicting the risk of death.
“In fact, once CRF was factored in, body weight failed to predict the risk of mortality. This is why it’s so important to understand the effects of this new class of drugs on it.”
The team concluded that GLP-1 drugs “significantly reduce body weight and adiposity, along with a substantial FFM [fat-free mass] loss, but with no clear evidence of CRF enhancement.”
Read more in the Journal of Clinical Endocrinology & Metabolism.