im not a consultant so dont know the whole science behind it, but i do know that your hexa's and hexb's are there for your healthy amounts of fibre and calcium that you need to make your body healthy, so think its best you have them!! i cant see missing a couple of days will hurt (ive been known to do this!) but you shouldnt leave them out altogether. for a start you would get "bunged up" with a lack of fibre!!!!!! lol