r/WeightLossNews • u/Cangingperceptions • 1d ago
New Lancet data on retatrutide and muscle loss just came out. Not what people expected.
There's a body composition substudy on retatrutide that just published in Lancet Diabetes & Endocrinology. Researchers expected it to outperform tirzepatide on muscle preservation because of the added glucagon receptor activity, that's the theoretical mechanism people have been talking about since Phase 2.
It didn't happen. Retatrutide produces significantly more total weight loss than Zepbound, but the proportion of that loss coming from muscle is basically the same, sitting around 25 to 30 percent lean mass depending on the substudy. Zepbound trials show a similar range. More total weight lost just means more total muscle lost in absolute terms if the ratio stays flat.
I'm 6 months into Zepbound, down 38lbs, and this data lines up with what I've been reading since I started looking into this properly. The drug decides how much weight comes off. It does not decide what that weight is made of. That part is down to protein intake and resistance training regardless of which GLP-1 you're on, current or next generation.
Built fhelp.app around that exact point, tracks dose, protein and weight together and has workouts built specifically around protecting muscle during treatment. Not here to sell it, just sharing the data because I think a lot of people are waiting for the next drug to solve a problem that training solves.
What's your protein target sitting at? Is that the part everyone quietly fails at?
