Exercise Should Be an Essential Part of GLP-1 Treatments, Says Research

Last month, HFB reported that HFA was part of a global coalition calling for physical activity to be central to treatments with GLP-1 medications. Joining HFA in the position statement were the World Obesity Federation, AUSactive, Exercise New Zealand, the Fitness Industry Council of Canada, and ukactive.

GLP-1 receptor agonists—including tirzepatide, semaglutide, and liraglutide—have transformed obesity treatments over the past several years. But the drugs come with a well-documented side effect: The joint position statement follows years of research that shows significant muscle loss from GLP-1 medications. According to the American Diabetes Association, “Lean body mass can account for up to 15% to 40% of total weight loss from GLP-1 therapies.”

Other research backs this up. A 2025 narrative review published in the European Journal of Clinical Investigation, drawing on PubMed data through August 2025, put the lean body mass loss figure at approximately 20% to 40% of total weight lost—and flagged the risk of sarcopenia, particularly in elderly patients and those with chronic metabolic disease.

Muscle loss at these rates can reduce bone density, increase fatigue, diminish strength and balance, and increase risk of injury. The Harvard Science Review published an analysis of “long-term clinical data from 2025 and 2026” and concluded: “Up to 40% of the weight lost on high-efficacy GLP-1 medications is not fat; it is lean body mass. As millions of patients age while on these therapies, researchers are urgently investigating how this pharmacologically induced muscle loss is accelerating sarcopenia, altering metabolic rates, and impacting human longevity.”

The problem of muscle loss from GLP-1 treatments is beginning to worry health authorities.

“As we enter a new era of obesity treatments, it’s vital to focus not just on the amount of weight lost but on preserving muscle mass and gaining the health benefits that result from treating obesity,” Samar Hafida, vice president of Obesity Association, a division of the American Diabetes Association, said in a statement.

Structured Exercise Is the Way Forward

Adding to the urgency of the joint statement from HFA and fellow stakeholders is the rise in use of the medications. Use of GLP-1 drugs increased by 586% from 2019 to 2024, With more telehealth services prescribing these drugs and oral versions being introduced to the market, the pace will certainly accelerate. According to Fortune Business Insights, in the United States alone, the market for GLP-1 and similar medications will grow from $73.39 billion in 2026 to $254.19 billion by 2034.

A possible weight-rebound problem is an added concern. Patients who discontinue GLP-1 therapies regain approximately 60% to 67% of their lost weight within the first year after stopping treatment, according to University of Cambridge. Given real-world data indicating that most patients who discontinue using these drugs do so within the first two years, this rebound represents a significant challenge to long-term outcomes.

Despite these concerns, GLP-1 medications are still an important tool in reducing the rise of global obesity, an issue that requires urgent action. The World Obesity Federation predicts that “the global economic impact of overweight and obesity will reach $4.32 trillion annually by 2035 if prevention and treatment measures do not improve.”

This is where the fitness industry can play a vital role. Researchers and healthcare professionals are becoming more aware of one key fact: Exercise, particularly resistance training, is one of the most evidence-supported interventions for mitigating muscle loss from GLP-1 therapies, slowing weight regain after cessation of treatment and supporting overall quality of weight loss.

Research presented at the European Congress on Obesity (ECO 2025) suggested that adults taking GLP-1 drugs who engaged in strength training and consumed adequate protein were able to retain muscle while losing weight. Other studies back these conclusions. (See sidebar below.)

The World Health Organization has also joined the call for pairing exercise with use of GLP-1 drugs. (See sidebar at right.)

In the coming weeks, HFA will publish a new multinational white paper examining the economic value of combining GLP-1 therapy with structured exercise. Developed in collaboration with fitness sector partners across multiple countries, the study moves the conversation from clinical rationale to health economic impact, showing how an integrated approach supports more durable outcomes and generates greater healthcare cost savings than GLP-1 use alone.