Adding the clinical framing, because it changes how the question reads. The distinction that resolves most of these threads is between what is true on average and what is true for one person. Both are real; they answer different questions and get quoted as if they were the same one.

MASHdoc_SA said:

The distinction that resolves most of these threads is between what is true on average and what is true for one person.

Adding a me-too, because a thread of one person's experience is not much use. Nothing to add that would improve it.

Moderator note: a couple of off-topic posts removed. Tagging this one for the weekly digest.

The figures, for anyone assembling their own picture. The boring version of this is the one that works, and the boring version is: measure a baseline, change one variable, wait, measure again under the same conditions. Nobody wants that answer and it is still the answer.

A narrower follow-up, since the general answer is now clear:

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