Ozempic Users Are Moving Less, Not More — New Fitbit Study Finds
People losing weight on Ozempic, Wegovy, Mounjaro, and Zepbound are moving less — not more — after starting the medications, according to research presented Saturday at ENDO 2026, the Endocrine Society's annual meeting in Chicago.
The finding runs counter to a common assumption. Many people expect that shedding excess weight naturally makes movement easier, prompting more activity as a side effect of the drugs' success. According to ScienceDaily, researchers found the opposite: physical activity declined after participants began treatment, despite successful weight loss.
How the Study Was Conducted
The research drew on a uniquely detailed data source — wearable fitness tracker records linked to electronic health information.
Researchers analysed data from the National Institutes of Health's All of Us Research Program, which combines electronic health records with Fitbit activity data. The study began with 1,950 adults with obesity who started a GLP-1 medication. Of those, 753 participants had sufficient wearable-device data to be included in the final analysis.
Most participants were women (78.6%), with an average age of 52.7 years. Researchers compared each participant's physical activity before and after they began taking the medication, focusing on two measures: daily step counts and minutes of moderate-to-vigorous physical activity (MVPA).
According to the researchers, this is the first large study to use wearable fitness tracker data specifically to examine physical activity patterns among adults taking GLP-1 receptor agonists — a class of drugs that includes semaglutide (Ozempic, Wegovy), tirzepatide (Mounjaro, Zepbound), liraglutide, and dulaglutide.
📰 Related: Hormone-Disrupting Chemicals Found in Up to 92% of US Breast Milk Samples — Study Confirms
The Numbers Behind the Decline
The data showed a clear and measurable drop in movement.
Average daily step counts fell from 5,047 to 4,487 steps per day after participants began treatment — a decline of roughly 11%. Time spent in moderate-to-vigorous physical activity dropped from 28 minutes to 22 minutes per day, a reduction of about 21%.
The largest decreases were observed in men and in people who reported joint or muscle pain. Notably, factors such as age, heart failure, and a prior stroke did not significantly alter the findings — the activity decline appeared across the study population regardless of these health conditions.
Critically, researchers found no evidence that the weight loss itself led people to become more physically active afterward — directly contradicting the assumption that lighter bodies naturally move more.
📰 Related: GLP-1 Drugs: The Promises and the Troubling Side Effects Nobody Told You About
Why This Matters for Muscle Health
The activity decline intersects with a separate, well-documented concern about these medications: muscle loss.
GLP-1 drugs are highly effective at reducing body weight, but the weight lost is not exclusively fat. These medications can also contribute to a loss of lean muscle mass — making physical activity especially important for preserving strength during treatment, according to study leader Dr. Sajana Maharjan, M.D., of HSHS St. John's Hospital in Springfield, Illinois.
"While many assume that weight loss leads naturally to increased physical activity, our study suggests otherwise," Maharjan said, per ScienceDaily. "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."
The findings should be read with appropriate caution: as research presented at a conference, they are preliminary and have not yet undergone full peer review. Other research — including large-scale clinical trials — has indicated that muscle loss is not a major concern for most GLP-1 users, and that physical functioning generally improves while on these drugs. Separate preclinical research presented at the European Atherosclerosis Society Congress found that combining semaglutide with exercise preserved muscle function while delivering greater fat loss than either intervention alone.
📰 Related: Ozempic May Fight Addiction Too — Massive Study of 600,000 Veterans Finds Shocking Results
What This Means Going Forward
The practical takeaway from Maharjan's team is straightforward: exercise guidance needs to be built into GLP-1 treatment from the outset, not treated as a secondary recommendation.
For patients already at elevated risk of muscle loss — particularly older adults — a roughly 11% drop in daily steps and a 21% drop in moderate-to-vigorous activity time represents a measurable reduction in one of the few tools available to offset that risk. The researchers' call for "targeted interventions" suggests this could translate into structured exercise programmes being prescribed alongside GLP-1 medications, similar to how physical therapy is sometimes paired with other treatments.
For people currently taking or considering these medications, the findings reinforce a message that has appeared consistently across GLP-1 research throughout 2026: the drugs are a tool for weight loss, not a replacement for the broader lifestyle changes that protect long-term health.
Key Takeaways
- A study presented at ENDO 2026 found GLP-1 users became less physically active after starting treatment — despite losing weight.
- Average daily steps fell from 5,047 to 4,487 (~11% decline); moderate-to-vigorous activity fell from 28 to 22 minutes/day (~21% decline).
- The study analysed 753 participants from the NIH All of Us Research Program, using linked Fitbit and health record data.
- Largest declines seen in men and those reporting joint or muscle pain; age, heart failure, and stroke history did not change the pattern.
- Researchers found no evidence that weight loss itself increased physical activity afterward.
- Study leader Dr. Sajana Maharjan: "Exercise cannot be optional for people taking these medications."
Sources
- ScienceDaily / The Endocrine Society — People taking GLP-1 weight loss drugs like Ozempic started moving less
- Gizmodo — Ozempic Users Are Skimping Out on Exercise, Study Finds
- EMJ Reviews — EAS 2026: Exercise Unlocks Greater Benefits from Ozempic
