Many people think that fasting leads to food cravings, which will diminish the positive fasting effect. That's definitely not the case. Of course, the first meal after a fasting period might be a little bit bigger than usually, which is absolutely fine. However, researchers suggest that those after-fasting-meals only have about 10-20% more calories than usual meals, which is still less than the amount of calories one might have eaten without fasting. To put it in a nutshell: you will still be in calorie deficit and therefore lose weight.