At least for the 70s fad diets, there wasn't any sort of long-term benefit like that. When they stopped, people would return to their original weight, or maybe even a little more. Then they would freak out and go back to the diet again -- the infamous "yo-yo dieting."

But I do think it's true that there are two different sensations: hunger, versus wanting food because it's yummy. Maybe some future diet will pair a restrictive diet with some sort of guided meditation helping you discern the different signals your stomach can send you.

Or maybe Mounjaro and friends will make the whole point moot ;-)

Do you think Wegovy/Ozempic/Mounjaro also work due to placebo effect? It seems that over the past decade or two we’ve discovered (some elements of) the sophisticated physiological mechanism by which we regulate appetite, and it involves the production of various hormones within our lower intestinal tract. When some fad diet produces sharp appetite reduction, my general question is: what’s more reasonable? To assume placebo or disruption of this mechanism?

At very least I think it’s useful to reinterpret these extreme fad diet weight loss results in light of this knowledge, rather than defaulting to the (now obsolete) understanding that appetite is primarily determined by psychological effects.