I saw a great Tabitha Farrar recently on "normal" eating and how dumb it is to think we can go from prolonged restriction right to normal eating. There are things we need in order to be alive - air, water, food. If your air is being restricted, you don't breathe normally when it's available again, you gasp. If your water has been restricted, you are not casual about water when you have access to it again, you gulp. It's normal and necessary. Yet we think we can drastically restrict food, and then be super casual around it or only eat a little bit. That misconception carries over even to some eating disorder treatment providers. They are so concerned about overeating that they promote meal plans that would be inadequate for most people, let alone someone who has been in extreme energy deficit.
I really liked the air, water, food analogy. Why is food any different from the other two? They're all essential for life. The body responds accordingly when we are deprived. It's biology, not that we are weak-willed, greedy, or emotional.