I'm pretty flexible with the holiday...but ONLY the holiday! It's too easy to start justifying eating junk for several weeks during this time...my work party, hubby's work party, office cookie exchange, nibbling while baking for others, feeling impolite if you don't try some of a patient's homemade treats they've brought for the office, etc. So, my "rule" is to give myself license for 2 days, Christmas Day and the day after because that's when my sister comes down to celebrate.

It's my tradition to make lasagne for Christmas dinner (I've done it for years) and I'll eat it. Last year I ate enough of my favorite Christmas cookie to be on the verge of being miserable! One piece of fudge, etc. According to FitDay, I was up by about 6 lbs right after Christmas but it was all gone within 2 weeks of getting right back on plan.

I realize that, with all things, Your Mileage May Vary. And I agree that some folks don't seem to be able to "get back on the horse" after they've carbed-up for a day or two. You just won't know how you do until you give it a try.