mike.trainer_LA said:

There is also a quality change that the scan cannot see.

Filing a mild objection. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit. I think this board over-worries about lean mass. Some lean loss is obligatory — you need less muscle to move a smaller body, and preserving mass you no longer need is not a health outcome. The question is whether strength and function held, and mine did.

JakeBK_lifts said:

Two DEXA scans eleven months apart: down 24kg total, of which the scan says 6kg was lean.

My endo's protocol for lean mass plateau: if weight loss stalls for 6+ weeks at current dose, we go through this checklist before titrating up:

1. Food diary review — is intake creeping up?
2. Protein check — minimum 100g/day
3. Activity audit — steps + resistance training
4. Sleep quality — poor sleep kills GLP-1 efficacy
5. Stress/cortisol management

Only after addressing all of these do we increase the dose. Often fixing one lifestyle factor restarts progress without needing more medication.

RetaRick_CA said:

I think this board over-worries about lean mass.

OMG yes. lean mass + resistance training is the combo. Can confirm.

A narrower follow-up, since the general answer is now clear:

What fraction of loss being lean mass is actually normal, because the numbers quoted here range from 10% to 40% and cannot all be right?

Closing the loop on my own question.

Second scan under matched conditions, six months apart, same time of day: the lean number came back nearly a kilo higher than the panic scan. Strength was up throughout.