Nah, you can't ruin a diet unless you overdo it. What matters is how *often* you eat poorly. If you indulge only once in a while and don't go hog-wild, you will get no effect. Heck, I quickly lost more weight briefly after Thanksgiving.
I actually gained weight during most of December despite doing nothing different from usual, but I'm going back down now. The body is strange. The good thing is that I now weigh less than I did before graduating high school, and I feel a lot better than then as well. It's not just about losing the weight; eating better helped my body overall. I used to have sore knees just at the weight I have now, but that's been gone for a while since starting the diet.
