GLP-1 Users Move Less After Starting Ozempic or Wegovy, Wearable Data Show

Adults with obesity who lost weight on GLP-1 receptor agonists were moving measurably less after they started the drugs, not more, according to research presented June 14 at ENDO 2026, the Endocrine Society's annual meeting in Chicago.

The finding cuts against one of the more appealing assumptions in GLP-1 prescribing: that shedding pounds naturally makes people feel lighter and more inclined to be active. The data say otherwise.

The study, led by Sajana Maharjan, M.D., an endocrinologist at HSHS St. John's Hospital in Springfield, Illinois, pulled Fitbit activity records linked to electronic health records from NIH's All of Us Research Program. According to the Endocrine Society's press release, researchers identified 1,950 adults with obesity who started a GLP-1 medication and focused on the 753 who had enough wearable-device data to analyze before and after they began therapy.

On average, daily step counts fell from 5,047 to 4,487 after starting a GLP-1, and moderate-to-vigorous physical activity dropped from 28 minutes per day to 22, according to figures published by the Endocrine Society. That's a loss of roughly 560 steps and six minutes of meaningful exercise every single day. The declines were statistically significant and happened alongside, not instead of, real weight loss.

The groups hit hardest were men and people with musculoskeletal pain, who showed the largest drops. Age, a history of heart failure, and prior stroke did not change the results, according to the Healthline report on the study.

Why does that matter clinically? GLP-1 receptor agonists reduce fat mass and lean muscle mass together. As reported by EurekAlert from the Endocrine Society release, physical activity is the primary tool for preserving strength during that weight loss. A patient who's eating less and moving less is at compounded risk of losing muscle they can't easily get back, especially older adults, who start with less reserve.

This is the first large study to use wearable fitness tracker data specifically to examine activity patterns in GLP-1 users, according to the Endocrine Society press release. That matters because clinic-based activity questionnaires are notoriously unreliable. Fitbit data don't lie the way self-report does.

The study is a retrospective pre-post cohort, not a randomized trial, and the findings haven't been peer-reviewed yet as a published paper. Conference data come with caveats. But 753 people with wearable records tied to verified prescribing data is a reasonable real-world signal, not a fluke.

For clinicians writing GLP-1 prescriptions, the practical upshot is straightforward. Patients aren't going to spontaneously start exercising because the scale is moving. If their prescriber doesn't explicitly build activity counseling into the visit, it probably won't happen. That could mean the difference between a patient who keeps their muscle mass and function at year two versus one who's lost weight but ends up weaker and more fragile than when they started.

Maharjan's team recommended targeted interventions that pair physical activity support directly with medication prescribing. What that looks like in practice, including whether it requires a structured referral, a behavioral health component, or just a different kind of conversation at the follow-up visit, is the next question the field needs to answer.

Sources cited:
- Endocrine Society press release via EurekAlert (https://www.eurekalert.org/news-releases/1130958)
- Endocrine Society press release (endocrine.org) (https://www.endocrine.org/news-and-advocacy/news-room/2026/maharjan-press-release-endo-2026)
- Medical Daily, ENDO 2026 Fitbit study coverage (https://www.medicaldaily.com/glp1-ozempic-wegovy-physical-activity-decline-endo-2026-fitbit-study-475671)
- Healthline, GLP-1 exercise coverage (https://www.healthline.com/health-news/people-taking-glp-1-weight-loss-less-exercise)