Accepted answer
Take the SURPASS-2 body-composition substudy, not the main paper, and note how few participants were in it. Composition substudies are typically a small imaged subset of the full randomisation, so the lean-mass fraction carries a confidence interval far wider than the weight figures beside it. Then check the method: DEXA reports lean soft tissue, which includes water, and a large early fluid shift is counted as lean loss whether or not any protein left. The fraction most of these programmes land near is around a quarter of total loss, which is also roughly what caloric restriction alone produces — the interesting question is not the fraction but whether it differs from the deficit-matched control.
This is measurable rather than arguable, provided you use the same instrument under the same conditions each time.
Resistance training two to four times weekly with progressive load is the intervention with the strongest evidence for reducing the lean fraction of loss. Cardiovascular exercise does not substitute for it on this endpoint.
Protein target arithmetic
| Body mass | 1.2 g/kg | 1.6 g/kg | 2.0 g/kg | Per meal at 1.6 (÷3) |
|---|
| 62 kg | 74 g | 99 g | 124 g | 33 g |
| 74 kg | 89 g | 118 g | 148 g | 39 g |
| 88 kg | 106 g | 141 g | 176 g | 47 g |
| 103 kg | 124 g | 165 g | 206 g | 55 g |
| 124 kg | 149 g | 198 g | 248 g | 66 g |
At roughly 4 kcal per gram, 141 g of protein is about 564 kcal — a substantial fraction of a 900 kcal budget, which is the real constraint.
Concretely, bone mineral density is measured on the same scan and falls slowly with weight loss; it is worth tracking on the same series rather than as a separate exercise.
Glycogen's water-binding ratio of roughly three to one is basic physiology and explains most early rapid weight change in any deficit.
Do not read the first fortnight as tissue loss. It is mostly glycogen and its water.
3Any published number for how long the counter-regulatory response persists? – Dr_Yusuf_Adeyemi 4 months ago 2Adding for future readers: same machine, same time of day, or the series is noise. – bufferline42 2 months ago add a comment