I did an interesting experiment. I fasted every other day for a month. It was about 30-35 hours of fasting every 48 hours. My belt no longer fit and it seemed to reset my metabolism. I have been eating a lot of carbs lately and it is just starting to show. I will probably do 2-4 weeks of it again.
I did consume a lot of water with added minerals and as much vinagre, lemon juice, and lime juice as I wanted whenever I wanted. That made it really easy.