Many patients expect movement to increase once weight starts falling. The logic seems obvious: less weight, easier stairs, more energy, more exercise.
That is not always what happens.
Research presented at ENDO 2026 used Fitbit data from adults with obesity who started a GLP-1 medicine. Among the 753 people with enough wearable data for analysis, average daily steps and moderate-to-vigorous activity fell after treatment began.
This does not prove Ozempic, Wegovy or Mounjaro directly caused people to move less. It does show something clinically important: weight loss medication does not build a maintenance lifestyle by itself.
Élan view: if movement falls while weight falls, the scale can look successful while the maintenance system becomes weaker. Exercise cannot be treated as decoration after the medicine works.
What the wearable-data study found
The study analysed data from the United States National Institutes of Health All of Us Research Program. Researchers identified 1,950 adults with obesity who started a GLP-1 medicine. Of these, 753 had enough Fitbit data for the before-and-after activity analysis.
In the included group, most participants were women, and the average age was 52.7 years. After treatment started, average daily steps fell from 5,047 to 4,487. Time spent in moderate-to-vigorous physical activity fell from 28 minutes to 22 minutes per day.
The data were presented at a medical conference, not yet as a full peer-reviewed paper. That means the finding should be read as a signal, not as final proof. But the signal is useful because it matches a common clinical problem: appetite improves before routines do.
Why this matters during GLP-1 weight loss
Weight loss is not the same as health gain. During treatment with semaglutide or tirzepatide, a lower weight can come with better appetite control, better blood pressure, better glucose markers and less strain on joints. But the body also adapts to weight loss.
If food intake falls and activity also falls, the patient may lose more non-fat tissue than necessary. Trial measurements of lean mass are not the same as pure skeletal muscle. Lean mass can include water, glycogen, organ and liver mass, connective tissue and muscle. Still, muscle preservation is one of the practical goals of supervised weight management.
Movement also helps the parts of maintenance that medication does not fully solve: balance, strength, cardiorespiratory fitness, mood, sleep, glucose handling and confidence in daily life.
The common trap: waiting until goal weight
A patient may think: first I lose the weight with Ozempic, Wegovy or Mounjaro, then I start exercising.
That is understandable, especially if nausea, fatigue, joint pain or embarrassment around fitness has been part of the story. But it creates a weak handover. When dose reduction, side effects, cost pressure, travel or medication breaks appear, the non-medication system is still immature.
For Élan Clinic, this is why maintenance starts during weight loss, not after it. The question is not whether a patient can complete an ideal training programme. The question is whether the patient can build enough repeatable movement to protect the result.
A practical movement check for patients on GLP-1 treatment
If you use Ozempic, Wegovy or Mounjaro, do not judge progress only by weight. Track whether your movement system is improving or quietly shrinking.
For many patients, the first target is not heroic exercise. It is a floor: a minimum amount of walking and basic resistance work that survives busy weeks, travel, side effects and weight plateaus.
When activity falls, do not assume laziness
A drop in movement has several possible causes. Some are behavioural. Some are medical.
Reduced food intake can reduce spontaneous movement. Nausea, constipation, reflux or dehydration can make exercise less attractive. Rapid dose escalation may worsen symptoms. Joint pain can limit walking. Low mood, poor sleep, anaemia, thyroid disease, diabetes medicines and other conditions can also affect energy.
The useful response is not blame. It is review. If activity falls while treatment continues, a physician-led plan should check dose tolerability, food intake, protein pattern, hydration, constipation, sleep, pain and other medicines before simply telling the patient to try harder.
What a maintenance-focused clinic does differently
A prescription-only model can treat exercise as optional advice. A maintenance clinic should treat it as part of the treatment architecture.
That does not mean forcing the same gym plan on every patient. It means matching movement to the person: walking for continuity, strength training for muscle and function, and enough follow-up to adjust when side effects or plateaus appear.
The goal is not to make GLP-1 treatment harder. The goal is to make the result more durable.
Weight loss should build a stronger maintenance system.
Élan Clinic helps patients using Ozempic, Wegovy or Mounjaro protect muscle, activity and long-term weight maintenance. If your weight is changing but your energy, strength or movement is falling, book a consultation and bring your medication history, dose and recent weight trend.
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- Maharjan S et al. Physical activity after GLP-1 receptor agonist initiation using Fitbit and electronic health-record data from the All of Us Research Program. Presented at ENDO 2026, the Endocrine Society annual meeting, 2026. Observational wearable-data analysis; 1,950 adults with obesity identified, n=753 included in final Fitbit analysis. Conference abstract and Endocrine Society release, not yet a full peer-reviewed paper.
- Jastreboff AM et al. Tirzepatide once weekly for the treatment of obesity. New England Journal of Medicine. 2022;387(3):205-216. Phase 3 randomised controlled trial; n=2,539.
- Wilding JPH et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension. Diabetes, Obesity and Metabolism. 2022;24(8):1553-1564. Randomised trial extension; n=327 in extension analyses.