well youre supposed to lose 1-2 lbs per day of fast....3500 cal are in 1 lb of fat...so you will burn your BMR plus some..if you exercise (not recommended) youll burn even more...i think its good to exercise the first day, but as you get weaker, you should only take light walks, just to keep your metabolism going....but other than that about a 1 lb a day is what youll lose fasting, good luck we're here w/ ya!