Headache

Hi,
I started a 3 day fast which ended at 1 1/2 days because of the severe headache which stayed with me for over 24 hours.
I really didn't have that much trouble not eating but once the headache came and stayed for 7 hours I knew the fast was over.
I know that there's supposed to be a headache but is there anyway to work up to the fast and not get that kind of a headache. Is everyone else's headache that bad?
I did have to get up and drive somewhere which didn't help the headache.
The book I bought really doesn't address the headache issue nor does it tell me how long it normally lasts. Any body know of a book that talks about the phases of fasting?

Thanks,
Susie