People on GLP-1 Drugs Are Moving Less, New Fitbit Data Shows

What the Researchers Tracked

At ENDO 2026, the Endocrine Society's annual meeting held June 13-16 in Chicago, Dr. Sajana Maharjan of HSHS Saint John's Hospital in Springfield, Illinois, presented a study that did something most GLP-1 research doesn't: it looked at objective movement data, not just the number on the scale.

Using the National Institutes of Health's All of Us Research Program, the team identified 753 adults with obesity who had started a GLP-1 receptor agonist — the drug class that includes semaglutide (Ozempic, Wegovy), liraglutide, dulaglutide, and tirzepatide (Mounjaro, Zepbound) — and who also had Fitbit activity data covering time both before and after they began treatment. The cohort skewed toward women (78.6%) with a mean age of 52.7, and came in with a fair amount of existing wear and tear: 81.9% reported musculoskeletal pain, 67.3% had hypertension, and 48.1% had type 2 diabetes.

The Finding: Steps and Exercise Both Dropped

After starting the medication, average daily steps fell from 5,047 to 4,487 — a drop of about 560 steps a day. Moderate-to-vigorous physical activity fell too, from 27.9 minutes a day to 22.2 minutes. The decline was largest among men and among people already dealing with joint or muscle pain; age, heart failure, and prior stroke didn't change the pattern.

Notably, the researchers found no evidence that losing weight on these drugs led people to move more, even though lower body weight generally makes movement easier. If anything, the data points the other way: people were doing less, not more.

One Important Caveat First

This research was presented at a scientific conference and has not yet completed peer review or appeared in a published journal. Conference presentations share early findings with the field, but the methods and conclusions can still be refined before formal publication. Treat this as a meaningful early signal, not a settled result.

Why This Is a Body Composition Story, Not Just a Weight Story

The headline number on a GLP-1 medication is almost always the scale. But weight loss on these drugs isn't purely fat loss — a meaningful share of what comes off is lean muscle, and muscle is maintained largely through use. If physical activity is declining at the same time weight is dropping, that's a setup for losing more muscle than intended, not less.

This is especially relevant heading into and through perimenopause, when muscle mass and bone density are already harder to hold onto for hormonal reasons. Combining that backdrop with a medication-driven drop in daily movement is worth knowing about before it becomes a pattern that's hard to reverse.

Staying Active While on a GLP-1

None of this is a reason to avoid these medications — for many people, they are genuinely effective tools. It's a reason to treat movement as its own variable to manage deliberately, rather than assuming it will take care of itself once the weight starts coming off. A few things this study suggests are worth a conversation with a healthcare provider: whether resistance training is part of the plan (not just cardio or step count), whether joint or muscle pain is being addressed rather than just worked around, and whether protein intake is adequate to support the muscle that is being used.

The practical takeaway isn't complicated: don't assume the scale is telling the whole story. Steps, strength, and how capable your body feels day to day are worth tracking right alongside weight.

What This Is, and Isn't

This is a report on an early-stage research finding about real-world activity patterns in people taking GLP-1 medications. It is not medical advice, and it is not a recommendation to start, stop, or change any treatment or exercise routine. Decisions about GLP-1 drugs — which are prescription medications — belong with a qualified healthcare provider who knows your history.