People with severe obesity who exercise regularly have healthier blood vessels and lower inflammation than those who rely on weight-loss medication alone, according to a new study from the University of Copenhagen — even after both groups have already lost significant weight.

Researchers followed 130 people with severe obesity for one year after they completed a low-calorie diet and lost an average of 13.7 kg (13 percent of body weight). Participants were then randomly assigned to one of four groups: exercise only, the weight-loss drug liraglutide only, exercise plus liraglutide, or placebo. Those who exercised developed healthier blood vessels and lower inflammation; medication alone helped maintain the weight loss but did not improve vascular health.

“The study shows that while medication supports weight maintenance, it is exercise — with or without medication — that improves vascular health.”

Signe Torekov, Professor, Department of Biomedical Sciences, University of Copenhagen

A Measurable Difference in Artery Health

After one year, the researchers measured the thickness of participants’ carotid artery walls, a marker of cardiovascular risk — the thicker the wall, the greater the risk of atherosclerosis, blood clots, and stroke. Participants who exercised saw a 6 to 7 percent reduction in artery wall thickness, with no improvement seen in the liraglutide-only or placebo groups. Levels of several inflammatory markers, including IL-6 and IFN-gamma, also fell among the physically active participants; combining exercise with medication produced further weight loss and additional improvements in vascular function.

“Medication can help maintain weight loss, but exercise provides additional health benefits that we do not see with medication alone.”

Rasmus Sandsdal, medical doctor and PhD student, first author

Two and a Half Hours a Week

The effect didn’t require intense training. Participants in the exercise groups trained an average of around two and a half hours a week, mainly spinning and circuit training, with activity measured objectively using heart-rate monitors.

“What is striking is how little it takes. Replacing just a few hours of screen time each week with physical activity improves cardiovascular health.”

Signe Torekov

The participants, in their mid-40s, had not yet developed diabetes or heart disease at the study’s start, which the researchers say makes the finding especially encouraging. “The participants were in their mid-40s and had not yet developed diabetes or heart disease, so it’s encouraging that even a modest amount of exercise can improve key risk factors for cardiovascular disease,” Sandsdal said.

The study used liraglutide, an earlier-generation GLP-1 weight-loss drug, so the results can’t be directly applied to newer medications such as semaglutide (marketed as Wegovy) — though liraglutide maintained weight loss at a comparable level in the trial. The researchers emphasize that exercise should remain a central part of treatment for severe obesity, especially as more people turn to weight-loss medication.

“Weight-loss medication is an important tool, but our results indicate that it cannot replace exercise. Physical activity remains essential for protecting the heart and blood vessels.”

Signe Torekov

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The study, “Effects of exercise and liraglutide on vascular health and inflammation during weight loss maintenance: a prespecified secondary analysis of the S-LiTE trial,” was published June 24, 2026, in Nature Metabolism (DOI: 10.1038/s42255-026-01554-4).