While GLP-1 receptor agonists (RAs) have transformed the management of Type 2 diabetes and obesity, concerns remain regarding their effects on skeletal muscle, particularly the reduction in lean body mass observed during therapy.
Weight loss is typically accompanied by reductions in both fat and muscle mass. Although accumulating evidence suggests that GLP-1 RAs lead to modest decreases in absolute muscle mass, these changes are typically proportional to total weight loss and may be accompanied by improvements in muscle quality and metabolic function.
Across randomized trials and meta-analyses, reductions in lean body mass (all nonfat components of the body, including muscle, bone, connective tissue, organs, and water) with GLP-1 RA therapy typically account for approximately 12%-40% of total weight loss, with many studies reporting values toward the lower end of this range.
Reductions in absolute muscle mass appear to be smallest with liraglutide, but larger decreases have been observed with semaglutide and tirzepatide. Importantly, these changes appear to be consistent with expected physiologic responses to weight loss and do not exceed age-related muscle decline when adjusted for the magnitude of weight reduction.
Muscle quality – defined by such factors as intramuscular fat content, mitochondrial efficiency, insulin sensitivity, and microvascular perfusion – has emerged as a more meaningful determinant of strength and physical function than muscle quantity alone. Multiple studies demonstrate that GLP-1 Ras preserve or improve muscle quality, despite modest reductions in absolute muscle volume.
Data from preclinical studies and clinical trials suggest that muscle strength and physical performance are largely preserved during GLP-1 RA therapy.
Overall, recommendations emphasize that regular resistance and weight-bearing exercise, combined with sufficient dietary protein intake, are essential to preserving muscle mass and strength during weight loss. When GLP-1 RA therapy is implemented within this framework, the risk for clinically significant muscle impairment seems to be minimal and the metabolic and cardiovascular benefits remain substantial.
To find out more, CLICK HERE.
