Fitbit data has cast doubt over whether patients using GLP-1RAs are engaging in the regular exercise needed to boost the chances of maintaining long-term control over their weight.

Internal medicine specialist at HSHS St. John’s Hospital in Illinois, Dr Sajana Maharjan, shared details of a study of 753 patients with obesity who had been prescribed a GLP-1 at last month’s ENDO 2026 event in Chicago.

Dr Maharjan and colleagues used fitness tracker data from the All of Us Research Program cohort, looking at patient’s physical activity before and after starting on an obesity management medication.

The analysis found:

• Following GLP-1RA initiation, participants’ average steps decreased from 5,047 to 4,487,
• Minutes of moderate to vigorous physical activity fell from 28 to 22 minutes per day,
• The declines in activity were most pronounced for male patients and those with musculoskeletal pain.

More that 80% of the cohort studied had existing musculoskeletal pain, while two thirds had hypertension and just under half had a T2D diagnosis.

Changes in exercise patterns did not differ according to age, history of stroke or heart failure status.

The importance of exercise for obesity medication users has been in the spotlight ever since drugs like semaglutide and tirzepatide first came to market, with data suggesting long-term weight maintenance is more successful when physical activity is included in a treatment plan [link here].

Australia’s recent consensus guidelines on managing CVD risk backed GLP-1RAs for obesity management but stressed these must be used in concert with lifestyle modifications, including regular moderate-intensity activity and resistance training [link here].

This study provided real world evidence that rather than increasing patterns of exercise, losing weight with a GLP-1RA was associated with a slowdown of activity, the authors noted.

Dr Maharjan said the research showed a relationship between weight loss and exercise should not be automatically assumed.

“The findings in our study reinforce that exercise cannot be optional for people taking these medications. People need targeted interventions that encourage physical activity alongside medication for obesity,” she said.

The authors concluded that specific interventions were needed to make sure patients were encouraged to continue enough exercise, and these should be put in place at the same time as starting pharmacological treatment.