Weight Loss Drugs Linked to Reduced Physical Activity, Study Finds

People taking GLP-1 receptor agonists—medications like Ozempic, Wegovy, Mounjaro, and Zepbound—experienced a significant decline in physical activity after weight loss, according to a study presented at ENDO 2026, the Endocrine Society’s annual meeting. The research, led by Dr. Sajana Maharjan of HSHS St. John’s Hospital, analyzed data from 753 adults with obesity and found average daily step counts dropped by 11% and moderate-to-vigorous physical activity (MVPA) fell by 21% after starting treatment.

Why Are Patients Losing Activity After Weight Loss?

The study challenges the assumption that weight loss inherently boosts physical activity. Researchers noted that participants, particularly men and those with joint or muscle pain, saw the largest declines. “While many assume weight loss leads to increased movement, our findings suggest exercise cannot be an afterthought,” Maharjan said. The medications, which include semaglutide and tirzepatide, are known to reduce both body fat and lean muscle mass, complicating the relationship between weight loss and physical function.

How Was the Study Conducted?

The research used data from the NIH’s All of Us Research Program, combining electronic health records with Fitbit activity tracking. Participants began the study with an average of 5,047 daily steps and 28 minutes of MVPA, which fell to 4,487 steps and 22 minutes after starting GLP-1 therapy. The analysis excluded individuals with conditions like heart failure or stroke, but the trend remained consistent across demographics.

What Does This Mean for Patients?

Experts emphasize the importance of maintaining physical activity alongside medication. “Protecting muscle mass is critical for long-term health,” said Dr. Maharjan, who highlighted the need for targeted interventions to encourage movement. The study, the first to use wearable data to track activity patterns in GLP-1 users, underscores the complex interplay between pharmacological weight loss and physical health.

Key Takeaways

• GLP-1 medications like Ozempic and Wegovy may lead to reduced physical activity despite weight loss.
• Participants saw an 11% drop in daily steps and a 21% decline in MVPA after starting treatment.
• Researchers recommend combining medication with structured exercise to preserve muscle and mobility.

What’s Next for Obesity Treatment?

The findings add to growing discussions about the long-term effects of GLP-1 drugs, which have become a cornerstone of obesity care. While these medications effectively reduce weight, their impact on physical activity and muscle health remains a focus for further research. “This study highlights the need for a holistic approach to weight management,” said Dr. Maharjan, whose work was funded by the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases.

ENDO 2026 Study Summary | NIH All of Us Research Program