If you can't stick to your decision, there is nothing medicine can do to make you stronger-willed... if you really want to lose weight, put all of your heart in it and try to resist the urge to eat... if you can't it just means your mind is not in that place yet.... But there is a little trick that might help-drink a lot of water before you go to bed. It will make your stomach full and maybe will keep you from eating for a while. Also, a problem might be with the diet you are using-did you find it somewhere, or are you making it up yourself? You should be eating diversely, and balanced, only less calories. Five smaller meals a day are a good plan, but you need to balance sugars, fats, proteins, vitamins and make sure total calories count is less than you usual. That way you will feel good, and not hungry. If you are just starving yourself the whole day, it makes sense you are so hungry in the evening. Also, some physical activity will help you a lot.