GLP-1 Users Moved Less Despite Weight Loss
Get the Health newsletter
Daily health & science — research, biotech, public health, the studies worth knowing. Free.
- Researchers analyzing Fitbit data from 753 adults in the NIH's All of Us Research Program found that people starting GLP-1 medications saw average daily step counts fall from 5,047 to 4,487 and moderate-to-vigorous exercise drop from 28 to 22 minutes per day.
- Study leader Sajana Maharjan, M.D., of HSHS St. John's Hospital in Springfield, Illinois, said exercise "cannot be optional" for patients on these medications and called for targeted interventions alongside the drugs.
- The largest activity declines were seen in men and in people who reported joint or muscle pain — groups already at elevated risk for the muscle wasting these drugs can cause.
- GLP-1 receptor agonists (semaglutide, tirzepatide, liraglutide, and dulaglutide) can reduce lean muscle mass along with fat, making the post-treatment drop in movement especially concerning for long-term strength and health.
- Researchers found no evidence that losing weight with GLP-1 medications led people to become more physically active, directly contradicting the common assumption that shedding pounds makes movement easier.
- Presented at ENDO 2026, the study is the first large investigation to use wearable fitness tracker data to track activity patterns in adults taking GLP-1 receptor agonists.
- Factors including age, heart failure, and prior stroke did not alter the activity-decline finding; the analyzed cohort was 78.6% women with an average age of 52.7.
Why it matters: Roughly 753 GLP-1 users dropped about 560 daily steps and 6 minutes of vigorous exercise each after starting medication, with the steepest declines in men and people with joint or muscle pain — the very groups most vulnerable to lean muscle loss. For the millions now on Ozempic, Wegovy, Mounjaro, and Zepbound, the data suggest the drugs may undercut the exercise habits that protect long-term metabolic and musculoskeletal health.
