Right, and part of being built for those "periods of lack" is that our bodies tend to respond to them by slowing our metabolisms. That way when we're well fed again we store an even higher percentage of calories as fat in case of future famines.
My weight has been stable in the three months since stopping.
If your base calorie requirements drop because you have lost a bunch of weight, but you don't change your eating behavior after stopping the fast, then of course you will end up gaining the weight back. They have done studies on the "World's Biggest Loser" contestants that show this. The facile interpretation is that you "slowed your metabolism".