If one wants to be health concious, then one can eat sparingly for a couple of days before Thanksgiving, so they induldge themselves on the holiday, but still try to eat in moderation.
One meal is not going to kill anyone, but you don't have to overeat. Exercise combined with eating moderatly, should be done throughout the year. I agree it's very easy to overeat, but Thanksgiving is a day to be with people you care about, and enjoying their company.
Nobody puts a gun to one's head and tells them they must eat, until they need a Alka-Seltzer.
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"It doesn't cost "nuttin", to be nice". 
MOM
I just want to do the right thing! Uncle Joe, (my hero).