Probably not.  Shopping and carrying all those Christmas presents around burns up close to 190 calories.  That's a far cry from the 4,500 most eat in a typical Thanksgiving Day dinner.  However, one of the things I learned from my nutritionist when I went through the Victory Instutute for Weight Management classes, was this.  If you eat healthy and stay minimally active year round, one day of going crazy, even if you do it once a week, is not going to make you fat.  So indulge a little!