Too bad such knowledge and advice was buried by "you know who", and I don't mean Valdemort.
Fasting can work wonders - especially when followed by correct living. Prolonged fasts like yours should always be done under the supervision of a qualified naturopathic health care giver. I think that just about everyone would benefit from the occasional short term fast, regardless of how correctly they live.
The Dr. Johanna Brandt Grape Cure, which works much like a fast, can do the same thing.
Another is the 48 hour Watermelon fast, which has the added benefit of being able to dissolve kidney stones.