GLP-1s & Rheumatology: Balancing Weight Loss & Muscle Mass Concerns

The growing use of glucagon-like peptide-1 receptor agonists (GLP-1s) for weight management is extending beyond endocrinology and into fields like rheumatology, prompting a re-evaluation of traditional weight loss strategies. While these medications can induce significant weight loss, experts emphasize that sustained success and overall health benefits likely hinge on integrating lifestyle interventions alongside pharmaceutical approaches.

The Promise and Potential Pitfalls of GLP-1s in Rheumatology

GLP-1 receptor agonists, initially developed for type 2 diabetes, have gained prominence for their ability to promote weight loss. This is particularly relevant in rheumatology, where excess weight is increasingly recognized as a contributing factor to arthritis and autoimmune disease severity. Data suggest a link between adiposity – the accumulation of body fat – and disease activity, making weight management a potential therapeutic target. However, simply losing weight isn’t enough. the *way* weight is lost, and maintained, appears crucial.

“These medications lead to rapid weight loss, but when you stop taking them you gain weight regain,” explained Brian J. Andonian, MD, MHSc, assistant professor of medicine at Duke University, speaking at the Cleveland Clinic Basic and Clinical Immunology for the Busy Clinician symposium. “That weight regain is going to be adipose tissue primarily. We are really good at building fat, we are not so good at building muscle.” This highlights a key concern: the potential for regaining lost weight, and specifically, regaining it as fat rather than lean muscle mass.

This is particularly concerning for individuals with rheumatic conditions, who may already be predisposed to sarcopenia – the age-related loss of muscle mass and function. Sarcopenia can exacerbate joint pain, reduce mobility, and increase the risk of falls. A weight loss strategy that doesn’t prioritize muscle preservation could inadvertently worsen these issues.

Beyond the Numbers: The Importance of Body Composition

Andonian underscored that it’s not just Body Mass Index (BMI) that matters, but body composition. “This proves really the adiposity that is the concern, not just the BMI,” he stated. This distinction is crucial because BMI doesn’t differentiate between fat and muscle mass. Two individuals with the same BMI can have vastly different health profiles depending on their body composition.

Studies have shown that GLP-1s can improve pain and joint parameters in patients with osteoarthritis, as measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). This suggests a benefit beyond simply reducing weight, but the underlying mechanisms are still being investigated. Emerging research also indicates potential benefits in psoriatic disease, though the precise pathways involved remain unclear.

The Role of Lifestyle Interventions

The consensus among experts is that GLP-1s are most effective when combined with comprehensive lifestyle changes. This includes a focus on dietary modifications and, crucially, resistance or strength training. Strength training is considered the most effective therapy for combating sarcopenia and preserving muscle mass.

Conventional weight loss strategies, such as diet and exercise, remain essential components of a holistic approach. However, the integration of GLP-1s necessitates a more nuanced understanding of weight management. A slower, steadier approach, prioritizing muscle preservation and long-term sustainability, may be preferable to rapid weight loss followed by regain.

Unintentional Weight Loss: A Cautionary Note

While intentional weight loss is generally considered beneficial, unintentional weight loss warrants investigation. Andonian cautioned that unintentional weight loss can be a sign of underlying health problems and should not be ignored. This is particularly important in patients with rheumatic conditions, who may be at risk for malnutrition or other complications.

What’s Next: Research and Refinement

Further research is needed to fully understand the effects of GLP-1 medications on skeletal muscle in patients with rheumatic diseases. Specifically, studies are needed to determine the optimal combination of GLP-1s, dietary interventions, and exercise regimens for maximizing muscle preservation and improving long-term health outcomes.

The mechanisms by which GLP-1s impact autoimmune conditions like psoriatic disease also require further investigation. Current evidence suggests potential effects on T cells, intraepithelial lymphocytes, and Natural Killer T cells, but more research is needed to elucidate these pathways.

Ongoing clinical trials and observational studies will continue to refine our understanding of the role of GLP-1s in rheumatology and inform best practices for their use. The field is rapidly evolving, and healthcare professionals will require to stay abreast of the latest developments to provide optimal care for their patients.

Brian J. Andonian, MD, MHSc, can be reached at [email protected].

Source: Andonian B. Obesity, Metabolism & Inflammation: The GLP-1 Revolution and What’s Next? Presented at Basic and Clinical Immunology for the Busy Clinician, Feb. 28 to March 1, 2026; hybrid meeting.