Fasting = the worst way to lose weight long term.
Why?
When you fast and deprive yourself of the nutriets it needs to survive, what do you lose?
Fat, Muscle, Water, etc.
You can't fast forever or you will die. So when you get back to eating like you should, you will gain all that weight back and then some. Depriving your
body of nutrients is actually counter-productive to big, long-term
weight loss. Not to mention it destroys your metabolism which is your
body's natural means of burning
calories.
Sure, as Leigh said, you will lose all that weight quickly. What happens after? you gain it all back. If you want to make a change for your life instead of a few weeks or months, then you should reconsider fasting. I'm not trying to be mean or anything, I'm simply trying to state facts so that you'll understand that fasting is NOT an effective means of longterm
fat loss.