GLP-1 drugs like semaglutide and liraglutide have changed the weight loss conversation by helping many people eat less and lose significant amounts of weight. But according to a new perspective published in JAMA, there may be an important catch: Losing weight is not always the same thing as protecting long-term metabolic health.
The article is not a new clinical trial, but rather an expert analysis from researchers at Pennington Biomedical and Harvard University examining how exercise fits into the growing GLP-1 era. Their central argument is simple: These medications may be powerful tools, but they do not replace the broader health benefits of physical activity.
GLP-1 medications can sharply reduce calorie intake, sometimes far more than standard exercise recommendations alone. But the authors argue that focusing only on the scale may miss a larger issue, especially when some weight loss may include fat-free mass such as muscle.
“Although GLP-1 receptor agonists offer powerful new opportunities for losing weight, they do not diminish the manifold benefits of exercise and instead highlight the need to translate exercise’s efficacy into effectiveness,” the authors wrote.
That distinction could matter for people thinking beyond short-term weight loss. Muscle plays a major role in physical function, metabolic health and healthy aging, and losing too much of it may increase concerns about frailty or sarcopenia, particularly for older adults.
The perspective also points to another major challenge: Many patients stop GLP-1 medications within a year, and weight regain after discontinuation is common. Exercise may help reduce that rebound, especially when it becomes part of a sustainable long-term routine.
But the authors also acknowledge reality: Exercise is hard for many people to maintain. Time, cost, physical limitations and even negative past experiences can all make adherence difficult. Rather than simply telling patients to “exercise more,” they argue clinicians should focus on individualized strategies that help people find practical, enjoyable forms of movement they can actually sustain.
This JAMA perspective was led by researchers from Pennington Biomedical Research Center and Harvard University. Reported disclosures were limited to one author’s book related to exercise biology.