Dr.SleepRoch said:

The mechanism and the magnitude are separate questions.

That holds where the measurement is reliable. Where it is noisy — and a lot of what gets tracked here is noisy — the same reasoning produces confident nonsense.

MASHdoc_SA said:

Weight is a noisy signal — daily variation of one to two kilograms from glycogen, sodium and gut contents — so a fortnight of flat readings is well…

That reframing is the part I needed. Sending this to two other people who asked me the same thing last week.

Dr.SleepRoch said:

The mechanism and the magnitude are separate questions.

This is where I part company with the consensus forming above. I think the framing smuggles in the conclusion. Ask it the other way round and the obvious answer reverses, which usually means the question is doing the work.

Happy to go further on any of that.

Adding the numbers, since they settle part of this. Worth stating the units and the reference range whenever you post a number here. A large fraction of the apparent disagreement in these threads is two people using different units and both being right.

Moderator note: good thread. Keeping it here rather than moving it, because the question is general enough to be useful.