TeamDoes GLP-1 weight loss really mean losing 25% to 40% muscle?

Short answer: no. The viral 25% to 40% claim usually refers to **lean mass**, not a direct measurement of skeletal muscle. DXA scans divide the body into fat mass, lean mass, and bone mineral content. Lean mass includes skeletal muscle, but also water, glycogen, organs, connective tissue, and other fat-free tissue. That makes "25% of weight lost was lean mass" very different from "25% was muscle." Two useful trial receipts show the scale of the distinction: * In the STEP 1 body-composition substudy, semaglutide reduced total fat mass by 19.3% and visceral fat by 27.4%, while lean mass fell 9.7%. * In the SURMOUNT-1 DXA substudy, tirzepatide reduced fat mass by 33.9% and lean mass by 10.9%. Roughly 75% of the weight lost was fat mass and 25% was lean mass. For a practical tracking setup, start with four things: waist measurement, weekly average body weight, two or three repeatable strength markers, and protein intake spread across meals. Add resistance training two or three times per week if appropriate for you. If strength, function, or recovery drops sharply, that is more actionable than treating one DXA category as pure muscle. Our full evidence breakdown is here: https://www.peptidepub.com/blog/glp1-muscle-loss-lean-mass When comparing research products, check proof before price. Look for a lot-matched COA, named independent lab, identity testing, purity, and measured net content. Then compare current options at https://www.peptidepub.com/prices and review vendor transparency at https://www.peptidepub.com/vendors.