Dr.PainCLE 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…

Pushing back on Dr.PainCLE here. 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.

LarryQC_SD said:

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

Regarding lean mass: I accidentally injected my dose intramuscularly instead of subcutaneously last week (went in at wrong angle, too deep). Called my pharmacist — they said it's not dangerous but may absorb faster, potentially causing more GI effects.

Sure enough, had worse nausea that day. Lesson learned: pinch the skin properly and use the right needle length for your body composition.

mike_nyc said:

I think this board over-worries about lean mass.

mike_nyc said:

...the muscle loss concern with lean mass...

This is a legitimate and well-studied concern. Let me put some numbers on it:

In STEP 1, approximately 39% of weight lost was lean mass. However, the Lundgren 2024 study showed that structured resistance training reduced this to ~25% lean mass loss.

Context matters: at BMI 35+, you're carrying excess lean mass to support the extra weight. Losing some lean mass is expected and not inherently harmful if you maintain adequate muscle function through exercise.

The solution isn't avoiding the medication — it's combining it with proper exercise and protein intake.

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

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

OP back with an update, since a thread like this is useless without one.

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.