Dr.EM_Chicago said:

Almost every unanswerable question in these threads is unanswerable because three things changed in the same fortnight, and no amount of subsequent…

There is a second half to this that has not been said yet. The honest answer is that the effect is real, the magnitude is contested, and the individual variation is larger than either. Those three things can all be true at once, and most arguments here are two people holding different parts of that.

The figures, for anyone assembling their own picture. One practical note: write down what you did and when, before you need it. Reconstructing a timeline from memory three months later is how people end up unable to answer the one question that would have resolved it.

Following on from Dr.EM_Chicago — and this may be the naive question:

How long did you give it before you decided it was working?

hank_denver said:

One practical note: write down what you did and when, before you need it.

I do not accept the framing. The question has been narrowed to the version that has a tidy answer, and the part that was dropped is the part the OP actually asked about.

Reporting back.

Follow-up — I put something in the gap where food used to be rather than waiting for the gap to close on its own. That was the part nobody told me.