Here are a few suggestions I gave for eating less on thanksgiving:
1) “Move to chopsticks!” Or, barring that, smaller plates and utensils.

2) Place the food “far away,” so people have to work (i.e., walk to the kitchen) to get another serving.

3) Start with a soup course, and serve other foods that are filling but low in calories.

4) Limit the number of courses.

Variety stimulates appetite. As evidence, consider a study conducted on mice. A male mouse and a female mouse will soon tire of mating with each other. But put new partners into the cage, and it turns out they weren’t tired at all. They were just bored. So, too, with food. “Imagine you only had one dish,” he says. “How much could you eat?”
5) Make the food yourself. That way you know what’s in it.

6) “Wear a very tight shirt.”

Enjoy

This advice also appeared here