#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 Ozempic, Wegovy, and Zepbound represent a step-function change in weight loss treatment, yet they introduce significant concerns regarding body composition and muscle preservation. Clinical observations reveal a troubling one-to-one ratio of lean mass loss to fat loss, where half of the weight shed may come from muscle rather than adipose tissue. This phenomenon differs markedly from traditional caloric restriction, where fat loss typically outpaces lean mass reduction. While DEXA scans provide data on these shifts, the impact on physical strength and bone density remains the most critical metric for long-term health. Mitigating these risks requires precise clinical counseling focused on high-protein nutrition and resistance exercise to counteract the physiological tendency to lose muscle. Emerging triple-agonist drugs like retatrutide further complicate this landscape, necessitating a deeper understanding of how pharmacological weight loss affects metabolic health beyond the scale.