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

Which effects tachyphylax and which persist, because the answer explains why tolerability improves while the appetite effect keeps working?

CarlaRPh_TPA said:

The mechanism is more central than most summaries suggest.

Filing a mild objection. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit. The objection nobody has made: this only works if the measurement is doing what we assume it is doing, and that assumption has not been tested here.

CarlaRPh_TPA said:

The mechanism is more central than most summaries suggest.

No disagreement, though the timescale matters more than the mechanism here. Most of what looks like a difference in kind turns out to be a difference in how long somebody waited.

CarlaRPh_TPA said:

The mechanism is more central than most summaries suggest.

Saving this. It is the first explanation that did not require me to already understand it. Taking it to my next appointment.

Adding the clinical framing, because it changes how the question reads. 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.