Physical Activity Declines After GLP-1 Initiation in Patients With Obesity

Patients with obesity who begin GLP-1 receptor agonist therapy experience a measurable decline in physical activity, according to data presented at the ENDO 2026 annual meeting in Chicago. Analysis of 753 patients showed that average daily step counts dropped from 5,047 to 4,487 following the initiation of treatment. These findings challenge the assumption that weight loss naturally leads to increased movement in a real-world setting.

Did You Know? The study utilized the NIH All of Us Research Program to link electronic health records with objective Fitbit data, moving beyond the limitations of self-reported activity levels often found in previous research.

Factors influencing activity decline

The reduction in physical activity was not uniform across the study population. According to the research, men experienced a significantly steeper decline in daily steps compared to women, with an average drop of 986 steps versus 445. Additionally, the decrease in moderate to vigorous physical activity was more pronounced in men, at 15.3 minutes compared to 2.9 minutes for women.

Patients suffering from musculoskeletal pain also showed higher susceptibility to reduced activity. Those reporting pain saw a mean decline of 679 daily steps, compared to a 22-step decline among patients without such pain. The study found no significant variation in these trends based on age, history of stroke, history of heart failure, or the presence of morbid obesity.

Clinical implications for weight management

Sajana Maharjan, MD, of HSHS St. John’s Hospital, noted that because GLP-1 medications reduce both fat and lean muscle mass, maintaining physical activity is essential to preserve strength and function. The data suggest that healthcare providers should not assume that weight loss will automatically trigger higher activity levels in patients.

Expert Insight: The findings suggest that the clinical approach to obesity management may need to shift toward a more prescriptive model. By integrating structured exercise counseling, resistance training, and targeted pain management at the start of therapy, clinicians could potentially mitigate the loss of muscle mass and functional capacity that may occur alongside fat loss.

What happens next

As GLP-1 usage continues to grow, clinical practice may evolve to include more robust monitoring of patient activity levels. Providers could increasingly rely on wearable technology to track progress and identify patients at risk for sedentary behavior. Future clinical strategies may involve proactive referrals for physical therapy for those with musculoskeletal conditions to ensure they remain mobile during their treatment journey.

Frequently Asked Questions

Did patients increase their activity levels after starting GLP-1 therapy?
No, the study found that average daily steps declined from 5,047 to 4,487 after patients initiated the medication.

Which patient groups saw the greatest decline in activity?
The declines were most pronounced in men and in patients who reported suffering from musculoskeletal pain.

Does age affect how activity changes during GLP-1 treatment?
No, the researchers found that the trends in activity decline did not vary by age, nor did they vary by morbid obesity status or a history of heart failure or stroke.

How do you track your own physical activity levels while managing your long-term health goals?