HI, I think I eat more in terms of calories than when i tried to lose weight the CW-way. When I was 19 I went on a 3 month diet where I ate as little as 450 cal daily. Needless to say it was horrible and stuffed me up for years after!
The wartmth in your body, especially the heat about 20 min after eating, is your body's metabolism, more specifically, its burning fat (well, thats what I was explained when I started the Leptin-reset anyway). I think its just a change for your body from burning carbs to burning fat. Its good to hear that you're feeling well though, you are lucky you have started this lifestyle so early.