Metabolic Brake or Muscle Catalyst? The Pharmacokinetics of GLP-1 Muscle Loss

While GLP-1 receptor agonists are not inherently "muscle-toxic," the rapid metabolic shift they induce can lead to a catabolic state that consumes lean tissue. In this episode, we dive into the pharmacology of semaglutide and tirzepatide, examining how slowed gastric emptying and blunted appetite signals impact the leucine threshold required for muscle protein synthesis. We explore the "glucose-alanine cycle," the role of myostatin inhibitors in future drug pipelines, and how adjusted protein dosing ($1.2$ to $1.6\text{ g/kg}$) can act as a pharmacological safeguard against sarcopenia.