GLP-1 Weight Loss Medications Linked to Reduced Physical Activity

Patients using GLP-1 receptor agonists, such as semaglutide and tirzepatide, may experience a significant decrease in daily physical activity following the start of treatment. Recent research presented at the Endocrine Society’s annual meeting, ENDO 2024, suggests that individuals prescribed these medications for obesity reduction saw an average decline of approximately 560 steps per day and a reduction in moderate-to-vigorous physical activity of nearly six minutes daily.

How Does GLP-1 Therapy Impact Daily Movement?

According to the preliminary study conducted by researchers at HSHS Saint John’s Hospital, the reduction in activity is not uniform across all demographics. The analysis, which utilized data from the All of Us research program, tracked 753 adults with obesity who were initiating GLP-1 therapy. Data showed that men experienced a steeper decline, averaging nearly 1,000 fewer steps per day compared to their pre-treatment baseline, while women showed a decrease of approximately 450 steps. Researchers measured these changes by linking electronic health records with data from wearable activity trackers, providing an objective look at behavioral shifts during pharmacological weight loss.

Why Is Maintaining Activity Crucial During Weight Loss?

Weight loss achieved through GLP-1 medications often involves a reduction in both fat mass and lean muscle mass. Clinical guidelines from the American Association of Clinical Endocrinology emphasize that without consistent resistance training and physical activity, patients are at a higher risk of sarcopenia—the loss of muscle mass and strength. While these medications effectively suppress appetite and promote caloric deficit, they do not replace the metabolic benefits of movement. Maintaining muscle mass is essential for sustaining long-term metabolic health and preventing weight regain once treatment is adjusted or discontinued.

What Are the Clinical Risks of Reduced Activity?

Even minor decreases in movement can have long-term health implications. A meta-analysis published in The Lancet demonstrates that even small increases in daily moderate-to-vigorous physical activity are associated with a lower risk of all-cause mortality. For individuals who are already sedentary, even five additional minutes of movement per day can produce measurable improvements in cardiovascular health. The decline observed in the HSHS Saint John’s study—a drop from 27.9 to 22.2 minutes of active time daily—moves patients in the opposite direction of these established health targets.

Addressing Behavioral Changes in Treatment

The study did not definitively conclude why patients move less once they begin GLP-1 therapy. However, clinical experts suggest several possibilities. Rapid weight loss can initially lead to fatigue or changes in energy levels, which may inadvertently discourage exercise. Furthermore, because the medication addresses hunger signals so effectively, patients may prioritize dietary changes over physical activity. Physicians are increasingly encouraged to include structured exercise counseling as a standard component of obesity management. Incorporating strength training at least twice a week is recommended to counteract the specific risk of muscle wasting associated with rapid, medication-induced weight loss.

Key Considerations for Patients

• Monitor Activity: Using wearable trackers can help patients stay aware of their daily step counts and activity duration.
• Prioritize Protein and Resistance: To protect muscle mass, clinical experts recommend high-protein intake paired with consistent resistance training.
• Consult a Provider: Patients noticing a significant drop in energy or activity levels should discuss these changes with their endocrinologist or primary care physician to adjust their lifestyle plan.

Note: The research cited was presented at a scientific conference and is considered preliminary. It has not yet undergone the formal peer-review process required for publication in a medical journal.