Don’t ever do this!
First off this combination of terms makes no logical sense, and unless you are prepping for a body building contest or embarking on a career important game the next day, you should never diet on this day.
If disallowing yourself the grandeurs of this holiday is so detrimental to your dieting, you may want to look at how effective your current routine is. A singular day does not impact that heavily unto your proposition for the other 365 days of the year, but I understand why people feel that they can not enjoy this day to the fullest.
Sometimes the fleeting feeling of abstaining from certain foods while everyone else is indulging may feel empowering. Instead, though it shows the flaws in your current methodology and provides a framework for what you should be doing all year round; not just this one day.
Commitment to diet and exercise is an ongoing dedication that is not predicated on single daily choices. Have you ever gone to the gym one day, and left the next day with 20 extra pounds of muscle? It never happens that way, and it is up to you to make diet and exercise a part of your daily life.
Be more concerned about your overall habits than focusing on singular instances. Don’t diet on Thanksgiving!