#398 ‒ AMA #86: GLP-1 RAs and muscle loss: new data, better questions, and how to preserve muscle during weight loss

GLP-1 receptor agonists like semaglutide and terzepatide induce significant weight loss, yet the associated reduction in lean mass often stems from rapid weight reduction rather than direct muscle wasting. DEXA scans frequently misinterpret changes in intramuscular adipose tissue and hydration as muscle loss, failing to capture true contractile tissue changes. Despite these reported lean mass declines, patients often maintain or improve physical function and grip strength, likely due to reduced physical load and improved metabolic health. Mitigating muscle loss requires prioritizing resistance training and high protein intake, ideally 1.4 to 1.6 grams per kilogram of body weight. While emerging drugs like retatrutide offer even greater weight loss potential, they necessitate rigorous adherence to lifestyle interventions to preserve functional capacity and bone health, as current data remains limited regarding long-term muscle preservation.