I fasted for 2 weeks once because I had contracted salmonella and typhoid all in one go... It was not pleasant and I lost a considerable amount of weight.
The only nourishment I could keep down was the residue water that rice had been cooked in, and fresh carrot puree, plus copious amounts of H20.
Oh, and lots of salt tablets (Gastrolyte), you suffer an awful lot of fluid and electrolyte loss due to dehydration.
Only try fasting after consulting a doctor, dehydration is a FAST killer and can leave some pretty serious side effects if left for too long.
My advice, try Yoga and meditation... it's safer.
Wiz