I do shorter fasts (10 - 21 days) but I like to do them every three months too.
I'm down 35 lbs in the last year over my four fasts and I expect to do approximately the same next year to reach my good weight.
This might seem slow to those looking for a quick fix, but I'm happy with it. I feel better than I ever have and junk food really does not taste as good to me as healthy food these days.