I'm so tired and I'm so full

I love Thanksgiving.  Had another round of food at supper tonight.  Why oh Why do I eat so much and that Pumpkin Pie is calling my name.  What is this phenomenom?????     The more I eat the more I want.  It should be once I meet my caloric intake I'm done.  But, its nuts.  I'm so full but I want more.  I'm so tired.  I just love tryptophin.