this is day 3 for me and ive had a headache all day, any one else have this trouble? does it go away? is it from lack of carbs, or just from being hungry all day? ive been starving all day (except 10 min after i eat) and totally tired. Im at about 2000 cal/day, is this enough (5'11", 197lbs, probably upper teens body fat%)? please respond if anyone has some suggestions.