People taking GLP-1 medications like Ozempic and Wegovy are moving less, not more, after starting treatment. That is the finding of a new study being presented at ENDO 2026, the Endocrine Society's annual meeting in Chicago.
According to Healthline, the study tracked 753 people with obesity who used Fitbit devices before and after starting a GLP-1 medication. Researchers pulled data from the National Institutes of Health All of Us Research Program, which links health records with Fitbit activity data. That allowed them to measure physical activity objectively rather than relying on self-reporting.
The numbers showed a clear drop. Daily step counts fell from an average of 5,047 to 4,487 after participants began their medication. Minutes of moderate-to-vigorous physical activity per day dropped from 28 to 22. The study found no evidence that weight loss from GLP-1 medications was associated with increased physical activity.
The group that saw the sharpest declines was males and people with musculoskeletal pain, meaning muscle or joint problems. Factors like age, prior stroke, or heart failure did not appear to change the results. The study population was 78.6% female, with an average age of 52.7.
Sajana Maharjan, MD, a board certified internist at HSHS St. John's Hospital in Springfield, Illinois, and the lead author of the study, addressed a common assumption about weight loss drugs in a press release. "While many assume that weight loss leads naturally to increased physical activity, our study suggests otherwise," she said.
Maharjan did not stop at the observation. "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 findings match what at least one physician says he sees in practice. Mir Ali, MD, medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, California, was not involved in the study but commented on the results. "This study aligns with my clinical experience. I often find that patients feel more fatigued while losing weight, which can make exercise feel like a chore," he told Healthline.
Ali also noted what reduced exercise can mean for patients on these drugs. A lack of exercise can lead to increased muscle loss, heightened fatigue, and suboptimal weight loss results, he said.
GLP-1 medications work by mimicking hormones that regulate appetite and blood sugar. They have grown sharply in popularity as treatments for both obesity and type 2 diabetes. Ozempic, Wegovy, and Mounjaro are among the most recognized names in the drug class. Their rise has prompted significant research interest into how they affect the body beyond appetite suppression and weight loss.
The study has not yet been published in a peer-reviewed journal. Presentation at a professional conference is an earlier stage of scientific review. Peer review involves independent experts evaluating the methodology and conclusions before formal publication.
The research team used data from the NIH All of Us Research Program, a large ongoing study designed to gather health information from a diverse population across the United States. By connecting electronic health records with wearable device data, researchers were able to capture real-world physical activity patterns rather than estimates.
The 753 participants in this analysis all had sufficient Fitbit data from both before and after starting their GLP-1 medication, which allowed for direct before-and-after comparisons within the same individuals. Common health conditions among participants included a range of comorbidities that often accompany obesity.
The study adds to a growing body of questions about how GLP-1 medications interact with other health behaviors. Weight loss alone has long been considered a driver of increased mobility and physical activity. These findings suggest that relationship may be more complicated, and that patients and their doctors may need to address exercise separately and deliberately as part of any GLP-1 treatment plan.
