For me, at the beginning it was hard to walk (the day I broke the fast). But after I was feeling better every time I I burnt more fat and sweat more. Weird, eh?
But really, the exercising was probably one of the BEST sessions of like 7 years of hard exercising (not naming the sport) I've had! It's just I felt bad at the beginning, but burning more fat and sweating off more crap made me feel better.
But really, the cells or whatever, they do grow from old cells. People gained weight (as The Fasting Doctor mentioned) on the fast (probably from muscles, your body I guess can do itself).
By the way, I think I might try a blog, because my posts get too long and too many.