Know exactly what you're going through. Have been through the exact same thing like a million times. One day you're up all bright and hopeful and swearing nothing will deter you from starving yourself and then three hours later you just happen to encounter a tiny cookie crumb - before you know it you've gobbled it up and decide you might as well chuck your diet just for today and begin afresh tomorrow. The trick is to forbid yourself even that teeny little cookie crumb. Although fasts have never worked for me. What is your calorie intake ?