I have fasted before, and I have liked that it helped me keep my weight down. But I did some stupid stuff that probably wasn't good for me. This would be my advice. If you do fast, when you come off the fast, like the next day (Sunday for you, I guess), eat really light foods--veggies, fruits, juices, soups, broths. Do not eat meat or bread or sugar. That will help ease your body back into food and not shock it or make it pack on pounds again. That's what I would say. I know that's sort of hard, because then it's like 2 days of restricted eating, but I think it might really be worth it.
And, when you fast, make sure you drink lots and lots of water. You want to be a pee machine when you fast. Seriously.