I want to to do a water fast, but I don't wanna kill my metabolism...?

I have not water fasted but I do the whole fast because I am Muslim.. but I do have to say is that it DOES not help in losing weight.. because when you open your fast you are twice as hungry and end up overeating.. Its better to eat in moderation then in extremes.. So i don't recommend that you do a water fast.. Exercise!