The holiday season seems to bring up a lot of guilt around food for people. They feel bad for eating "unhealthy" foods and then try to "make up for it" by skipping other meals or only eating salads for a week or something along those lines.
If your game plan for Thanksgiving involves skipping all meals until the actual Thanksgiving meal is served - STOP!
The only thing restricting food intake will do is set you up to overeat. One of your body's responses to food restriction is to make food even more appealing. So, when you do eat, it will likely feel so out of control that you'll barely enjoy the food anyway!
Just because you're going to a party in the evening doesn't mean your body stops requiring fuel to function throughout the rest of the day. By skipping meals in an attempt to "save up" calories for later, you're depriving your body of the valuable energy it needs to keep you going. Then, you'll show up to the family dinner ravenously hungry, eat far more than you otherwise would have, and will probably not feel all that great afterward.
What this desire to restrict or "save up" calories stems from is the idea that the foods typically served at Thanksgiving are "bad" or unhealthy.
In reality, there is no moral value assigned to food. You aren't "good" if you skip breakfast or eat salad, just as you aren't "bad" if you eat mashed potatoes, stuffing, and pumpkin pie. Food is just food. It is absolutely okay to eat a food simply because you enjoy it.
Thanksgiving is for giving thanks and spending time with loved ones, not guilt and shame over what we ate or didn't eat. So, feed yourself regularly leading up to your Thanksgiving meal, arrive comfortably hungry, and enjoy the foods you love without judgement.