Originally Posted by Liberty
I disagree that speed of fat loss has anything to do with it. Nor do I think that it is "unrealistic" to expect that eating more food will make you less hungry.
There is actually something to it, but not the way you'd expect. When you lose weight quickly, your TDEE decreases quickly as well. So in absolute terms, your maintenance goes down faster and you need to adapt to it faster. You can't get used to small decreases of food, but you suddenly need to eat "way less" to maintain. Psychologically, that's a big reason a lot of people fail.
Additionally, when you lose weight rapidly, your hormones down regulate pretty fast as well. I remember vaguely that a typical RFL run down-regulates your hormones as much as a comparable 8 week diet. Again, you need to get used to those adjustment in a much smaller time frame. Another reason why people may slingshot themselves out of the newly attained leanness.
To summarize, fast weight loss means fast adaptions which people cannot handle very well.