PedsEndoPhilly said:

The intervention that works is boring and well evidenced: resistance training two to three times a week at a genuine effort, protein at 1.4 to 2.0…

No disagreement with PedsEndoPhilly. One condition attached. 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 protein. Both numbers need a caveat that matters: "lean mass" on a DEXA is not muscle. It includes water, glycogen and the lean fraction of organs, and glycogen alone carries about three grams of water per gram. A large early lean drop is mostly the glycogen and water going, which is why the first scan flatters and the second is the honest one.

PedsEndoPhilly said:

The intervention that works is boring and well evidenced: resistance training two to three times a week at a genuine effort, protein at 1.4 to 2.0…

I read this differently from PedsEndoPhilly, on substance rather than tone. 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.

Short answer first, then the reasoning. There is also a quality change that the scan cannot see. Weight loss shifts fiber-type distribution toward Type I and improves mitochondrial density and insulin-stimulated glucose uptake per fiber — so the muscle you keep is metabolically better even though there is less of it. That does not make the loss irrelevant, but it explains why function often holds up better than the number suggests.

Ask again with the specifics and you will get a better answer than this one.

RetaRick_CA 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…

Same pattern here, and in the same order.