BariatricNurseD said:

The useful move here is to separate what is established from what is widely repeated.

Adding the part of the answer the thread has not reached. Whatever the answer turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, and invite the correction. That is slower than asserting, and it is the only version that survives being wrong.

The figures, for anyone assembling their own picture. Give anything pharmacological four weeks before you judge it, and give anything measured weekly a four-point rolling average before you call it a trend.

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

How would you tell the difference between that and the alternative explanation?

stefan_berlin said:

Give anything pharmacological four weeks before you judge it, and give anything measured weekly a four-point rolling average before you call it a…

Filing a mild objection. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit. Filing an objection on the n=1 problem. Personal experience is genuine evidence about one person and very weak evidence about anybody else, and this thread keeps promoting the first into the second.

stefan_berlin said:

Give anything pharmacological four weeks before you judge it, and give anything measured weekly a four-point rolling average before you call it a…

That is right for the common case. Whether it is right for the case being asked about depends on a detail that has not been given.