I agree with some of the other posts, if it's planned and not totally nuts you'll be OK.

A couple of weekends ago was my wedding anniversary. My husband and I had t-bone steaks, Caesar Salad (no croutons) and a bottle of cabernet. We then shared a tiny, single-serving size chocolate mud cake. It was the first of anything like that I had had since the end of January. I thoroughly enjoyed every bite. The whole dinner was delicious, rich and wonderful, AND LOW CARB except for the cake. A planned cheat can be done and not mess you up at all!

Good luck!