I don't know if I'm remembering this properly but there was an article on fat cells and the death of

Fat cells are long-lived but they do die. That, in fact, their longevity is programmed by body cycles of famine, i.e., if famine occurs approximately every 5-7 years, fat cells will live at least eight to 10 years or something like that to ensure it doesn't get caught short of stored fat when a famin arrives...even if it arrives a little later than expected.

Diet cycles stand in as famine cycles.

Fat cells multiply but don't shrink; they fill with water to keep them available for refilling during the next feast/pre-famine period as the energy needed to maintain them fat less is less than that needed to create new.

Water filled fat cells will refill with fat in preference to expending energy in preparation for the next famine.

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I remember when I found/read this article, it made a lot of sense to me.

So...
Fat cells dying and releasing contained water is what creates the "whoosh" of weight loss.

It explained plateaus.

It explained weight spriraling and the period before weight regain when it seemed like you were off the diet but not gaining weight for a while.

It explained why you really shouldn't restrict calories too much.. i.e., it mimics famine and leads to fat cell longevity and easy weight regain.

It explained why people could be turtles and/or never get the Atkins energy surge.