Traditionally, Thanksgiving is a time of year for being social with friends and family and sharing a big meal. The guys at jiujitsubrotherhood.com have a very informative article about nutrition for BJJ. Please read the link before continuing **insert Jeopardy music here**...
So here are your challenges during your meal:
Avoid Large Meals
Yeah right... Who will do that? That's the whole point of Thanksgiving right? To eat a LARGE meal. Can you limit your portions?
Limit Meat Consumption
Turkey, Ham, Roasts, etc are part of the traditional Thanksgiving meal. How many people will be having Tofurky this year?
Ask the food preparers if the Rolls/Breads are gluten free. But honestly, would you care if they weren't?
This has got to be the biggest challenge. I believe sugar is a drug. You can always try to only eat stevia prepared desserts but they may be hard to come by. You can just skip the desserts altogether...it may cut down your calorie intake tremendously.
Maximise Fruit and Vegetables Intake
No, cranberry sauce is not a fruit. It is probably full of HFCS...you might be ok if you go organic though.
And vegetables boiled in butter may not be too good for you either.
Avoid Processed Food Products and Preservatives
This all depends on the chef. If the food preparer takes time and care, most of your meal will be made from scratch. But with our high tech lifestyle, the "add water make food" mantra may take hold and people will sacrifice a quality meal to make more time to play candy crush on facebook.
Finally, this may also be an option. People may think you are weird or wonder why you are self-ostracizing. You can always say you refuse to sacrifice your performance on the mats by eating wrong. Or, you may go the route of mentioning the Pequot War.
"In 1637 near present day Groton, Connecticut, over 700 men, women and children of the Pequot Tribe had gathered for their annual Green Corn Festival which is our Thanksgiving celebration. In the predawn hours the sleeping Indians were surrounded by English and Dutch mercenaries who ordered them to come outside. Those who came out were shot or clubbed to death while the terrified women and children who huddled inside the longhouse were burned alive. The next day the governor of the Massachusetts Bay Colony declared "A Day Of Thanksgiving" because 700 unarmed men, women and children had been murdered."
Yeah...I think I may be fasting...