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

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View the Show Notes Page for This Episode Become a Member to Receive Exclusive Content Sign Up to Receive Peter's Weekly Newsletter In this "Ask Me Anything" (AMA) episode, Peter explores the effects of GLP-1 receptor agonists—including drugs such as Ozempic, Wegovy, and Zepbound—with a particular focus on their impact on muscle. He examines how much lean mass people actually lose during treatment and how those changes compare to weight loss achieved through other methods, while explaining why measurements of lean mass on DEXA scans can sometimes be misleading. Peter discusses the effects of these medications on bone mass, fracture risk, strength, and physical function, highlighting why functional outcomes may be more important than body composition metrics alone. He also explores how GLP-1–based therapies affect different fat depots throughout the body, identifies who may be most vulnerable to muscle loss, and outlines practical strategies for preserving muscle and bone health while using these medications. Finally, Peter reviews early insights into retatrutide, a next-generation weight-loss therapy, including what current evidence suggests about its effects on weight loss and muscle mass. If you're not a subscriber and are listening on a podcast player, you'll only be able to hear a preview of the AMA. If you're a subscriber, you can now listen to this full episode on your private RSS feed or our website at the AMA #86 show notes page. If you are not a subscriber, you can learn more about the subscriber benefits here. We discuss: The evolution of GLP-1 receptor agonists from diabetes drugs to breakthrough weight-loss therapies [1:45]; Early concerns about lean mass loss with GLP-1 receptor agonists and the limitations of clinical trial data [3:45]; How newer research has changed the understanding of lean mass loss on GLP-1 receptor agonists and why DEXA measurements can misrepresent muscle loss [6:15]; Comparing lean mass loss across semaglutide, tirzepatide, and traditional weight-loss interventions [10:30]; C