I've been hesitant to talk a lot about fasting 'cause I'm pretty much done with it myself.
But, yes, I have fasted numerous times, including two 30 day water fasts.
I've done one to three week water fasts quite a few times.
When I lost 150 lbs or so as a teenager I ate one meal a week for several months (usually an all-meat pizza on Friday night
The first day is the worst, but after the second or third day, it's clear sailing for a week or two. After that, it is really more psychological as all hunger stops.
Into week three, at least for me, the muscle cramps start up and get bad--you NEED to drink a LOT of water. I'm sure this is probably not the most healthy thing to do.
You DO lose a lot of weight, and the feeling is great, once the hunger pangs of the first couple of days subside. You will have LOTS more free time and will wonder at the hours once spent eating/preparing to eat.
You will feel euphoric and sometimes lightheaded, especially if you continue to exercise (which if you don't, you'll lose even more muscle tissue). You will probably feel cold.
You will pee a LOT if you are drinking anywhere near enough.
Other than the muscle cramps, it's really a pretty good experience. I will say, though, that it gives one a good understanding of how painful it would be to actually starve to death.
I think that one or two day fasts, perhaps with juice or something to help keep electrolytes in balance wouldn't be bad. Long water fasts, I don't know--they can kick off a low cal diet but in the long run, well, they didn't work out all that well for me (since here I am).
Hope this helps.
47 M 5'8"
May 4, 2010...... 440? lbs. (Start FitDay Size 60 Jeans)
June 19, 2010.... 393 lbs. (First Weigh-in)
June 19, 2011.... 229 lbs. (164 lbs. gone in one year :-)
Current Weight... 185 lbs. (Size 36 Jeans)
Next Goal 169 lbs. (07/04/12)
Ultimate Goal 165 lbs. (12/31/12)
The best exercises for weight loss are Fork Putdowns and Table Pushaways.