This week you have likely been deluged with fast-talking influencers on television talking about how to stick to your diet this holiday season. They don't know what they are talking about, next week the same group of thin, hurried, fast-talking, overconfident people will be making gift recommendations.
Calories are a marathon, not a one-day spring. If you are fat, binging for one day didn't cause it, it is the chronic overeating that did. I lived in Manhattan, with some of the best Italian food on earth. Somehow I gained 10 pounds? There was no mystery, it was eating stromboli every day and pretending it was a treat rather than a lifestyle.
Thanksgiving is a treat. It is not going to ruin your diet. Even Marion Nestle agrees, and she thinks food is part of a Vast Corporate Conspiracy.
Obviously if you are the kind of person who is all or nothing when it comes to pleasure - many alcoholics say they can't have even a drink or they go on a binge - then use your judgment, there is no blanket solution that applies to everyone, but that is the problem with those annoying morning shows turkey trotting out diet advice for holidays. They are shaming pumpkin pie, when it is almost guaranteed that the pumpkin pie did not make you fat. Nor was it the trans fats, or the sugar.
It's calories that matter, not the type of food. Not where you bought it, not what process label is on it. Worrying about one day is the dietary equivalent of trying to blame "endocrine disrupting chemicals" in food or the epigenetics of your grandparents' eating habits. It's a headfake to avoid the real issue. And the real issue is we are in a Golden Age of Food - it is cheap, nutritious, and plentiful, so we can all afford to be fat. However, indulging one day a year won't cause that.