Slightly off-topic, but it is related: chew your food. Seriously. I'm not being sarcastic.
I'm convinced so many of us eat with our eyes and completely forget what is going on with the whole process of eating.
By remembering to chew your food properly as opposed to shoveling it in your mouth like coal being shoveled into a steam engine provides a more extended period of time to complete the eating of a meal, giving you time to feel the process of 'filling up' and signalling that you've actually had a sufficient in take of grub. And your stomach will really appreciate it too.
I have to sometimes consciously stop for a minute now after I've put the plate in front of me, take stock of what I'm actually doing before I start eating and realize that what I'm obsessing about in my head has nothing to do with me sitting here just about to start eating. So, we come back to where we are, we eat and we chew,,,,and we chew so more, and then some more. Problem is, for most of us, chewing's pretty boring, and we'd rather get the next mouth full in to get that food-sensation thing going on - ummmm loverly, Homer Simpson style. Then we finish, look down, wonder were the food has gone and barely remember eating it!