LOL.. I could go a bigmac right now..
If I remember rightly from a lecture I was once given about food and exercise is that you have to make sure you "eat" enough energy to sustain the energy you are letting out by exercising. It related to metabolism as well because it can attack your muscles if the fat hasn't been "stimulated" from food.
I could be waaaaaaay off here, but it was something like that. I've had to take some painkillers and I'm not thinking 100% straight. Hopefully someone in here can correct me if I'm wrong.