This is not a diet site. But it is a site devoted to cooking and eating well, and so we cannot embark on the holiday season without mentioning a few thoughts. And we’ll start by simply repeating a few of Dr. Clower's thoughts, because they are sensible.
The key is high quality, low quantity. The problem with Thanksgiving, for example, is that although turkey is good for you, sweet potatoes are good for you (and so on) - "but it comes out on a forklift!" Very American... land of The Hummer and Big Gulps.
It all sounds simple, but for most people it is not. It takes a level of consciousness that most people, Americans in particular, do not practice.
If we could all just slow down and notice our food more, we would eat better. Notice the texture in each bit. Notice the temperature, the color, the scent it has before you put it in your mouth. Think about where it came from as you eat it. Guaranteed, over time, you will eat healthier food, and less of it.