Dr.AddMedPHL 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.

Adding the numbers, since they settle part of this. The arithmetic that makes it tractable: reference weight in kg times 1.6 gives the target; divide by four for a per-sitting figure; then find four foods that hit that figure in a volume you can actually finish. Most people need two of the four to be liquid or semi-liquid early on.

Dr.NateNeph said:

I think this board over-worries about lean mass.

Adding the part of the answer the thread has not reached. The RDA is the wrong reference and it is worth understanding why. 0.8 g/kg is the intake at which nitrogen balance is not negative in healthy weight-stable adults — a floor for deficiency prevention, not an optimum, and derived in a population that is not in a deficit. In a substantial energy deficit, protein requirement rises because amino acids are being oxidised for energy and because muscle protein synthesis is blunted. The literature on preserving lean mass during weight loss lands around 1.4 to 2.0 g/kg of reference body weight, which is roughly two to two and a half times the RDA.

One thing that is still open after anders_CPH’s answer:

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

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.