From the realage.com website, which sends me emails frequently:

"You Can Think Yourself Thin"
Here's a novel weight-loss strategy. Before you take one single bite, think about your last meal -- every detail.

It may sound silly, but there's science behind the idea. People in a study who thought about their last meal before snacking munched less. So before your next nibble, picture your lunch plate.

Mind over Matter
It made no difference how tempting the treat. When people were asked to remember what they had for lunch that day prior to eating a popcorn snack, they ate less of the munchy stuff -- regardless of whether it was seasoned or served plain. All of which suggests that appetite may be linked to food memory cues.