Keeping Muscle on GLP-1s

What shows up as lean mass on a dexa scan is technically fat-free mass, basically everything that isn't fat tissue. So that includes bone, skin, organs, all of it.

This class of medication drives fast weight reduction, which often takes lean muscle along with fat. Since muscle packs more density than fat, shedding a pound of it produces a much smaller drop in actual size. So if the loss skews heavily toward muscle, the number on the scale falls while your measurements barely budge, meaning clothes fit about the same.

Here's another source making the same point, since you don't seem to be following what I'm getting at.