You are not a FU. It is just yr body reacting to years,of carbs. Carbs are addictive. An MRI of a cocaine addict and an MRI of a sugar addict shows the same destruction. U would not be surprised at a cocaine addict slipping? Why hate yourself for slipping on sugar? I agree with the commenter who recommends no "cheat " days. U would not try a "little" cocaine would you?
Please forgive yourself, drink a lot of water, stretch, take a little walk, and eat lots of leafy greens.