New research in Cell Reports Medicine challenges the claim that GLP-1 drugs cause excessive muscle loss. DEXA scans, the standard measurement tool, lump together liver tissue and muscle, so the extra lean mass loss may be liver shrinkage, not muscle. A human trial found that while muscle size decreased on GLP-1, strength stayed fully preserved.
We've been totally wrong about muscle loss on GLP-1 weight loss drugs. Let me catch you up. So it's become common knowledge that people on weight loss drugs, GLP-1 receptor agonists, Ozempic, Wegovy, tirzepatide, retatrutide, lose more lean mass than people who just lose weight via diet and lifestyle alone, about 40% versus 25%. But there's a catch that was just clarified in brand new data published in Cell Reports Medicine. Basically, the DEXA scans that that have been used in the human controlled trial literature, they cluster together a lot of different tissues and organs as lean mass. So liver, muscle, and then different components in the muscle all go into one bucket. So it turns out a lot of the extra lean mass loss that we're seeing in the clinical trials are just things like shrinking livers, or your muscles getting rid of substrates it doesn't really need rather than the functional muscle components. In fact, in a proof of principle human trial in this study, They were able to show that while muscle cross-sectional area shrinks in humans on GLP-1s, maybe the muscle's just getting rid of stuff it doesn't need, the strength of the muscle doesn't diminish at all. In the upper and lower body, strength is 100% maintained. This really reframes how we think about muscle health on these weight loss drugs. This is just level 1. If you want to go to level 2, 3, 4, and get the deep nuances, check the long-form content and click subscribe to stay up to date on health information.
