NayNay, Tuscon is right. Don't start by beating yourself up. In fact start when you are feeling fairly good about yourself because it takes patience if you are doing it right.

What worked for me was finding a diet that makes sense to me and then following it. It's not easy but it does work because it gives me structure and if I question a food I just look in my book and know if I can eat it that day or if it's a bad idea overall or if it's fine tomorrow if I watch for other things.

Good luck and be gentle with yourself.