SleepDoc_PDX said:

The honest range is roughly 20 to 40% of total loss as lean mass without deliberate resistance training, and roughly 10 to 20% with it plus adequate…

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

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

Whether resistance training and protein change the ratio or only the absolute amount?

PeptideChemSF said:

lean mass + resistance training is the combo.

Back pain as a lean mass side effect: not from the medication itself, but from rapid body composition changes. Losing 58 lbs shifts your center of gravity and your core muscles need time to adjust.

Physical therapy has been essential. Core strengthening exercises (planks, dead bugs, bird dogs) daily for 10 minutes have eliminated my lower back pain. Your body is literally relearning how to carry itself.

Reporting back.

Second scan under matched conditions came back with the lean number nearly a kilogram higher than the first, so a chunk of what I panicked about was hydration. Strength numbers were up throughout.

sarah_TO said:

Back pain as a lean mass side effect: not from the medication itself, but from rapid body composition changes.

Right, and protein targets should be set on a reference weight rather than current weight. Setting 1.6 g/kg on a starting weight of 130kg produces a target nobody hits on a suppressed appetite.