Yo-yo dieting is actually quite common. You lose a bit of weight, and then end up gaining it back and more. It's hard to keep bad habits from returning, you may have a cheat day here and there and it creeps up on you. I've never tried fasting before, but I've heard it can help you lose weight. As long as you've got a routine and stick to it I think it's possible to keep the weight off for good.