Per Michael Pollan:
Don't eat anything your great grandmother wouldn't recognize as food. When you pick up that box of portable yogurt tubes, or eat something with 15 ingredients you can't pronounce, ask yourself, "What are those things doing there?".
Don’t eat anything with more than five ingredients, or ingredients you can't pronounce.
Stay out of the middle of the supermarket; shop on the perimeter of the store. Real food tends to be on the outer edge of the store near the loading docks, where it can be replaced with fresh foods when it goes bad.
Don't eat anything that won't eventually rot. There are exceptions -- honey -- but as a rule, things like Twinkies that never go bad aren't food.
Always leave the table a little hungry. Many cultures have rules that you stop eating before you are full. In Japan, they say eat until you are four-fifths full. Islamic culture has a similar rule, and in German culture they say, 'Tie off the sack before it's full.'
Families traditionally ate together, around a table and not a TV, at regular meal times. It's a good tradition. Enjoy meals with the people you love. Remember when eating between meals felt wrong?
Don't buy food where you buy your gasoline. In the U.S., 20% of food is eaten in the car.
In summation:
Eat real food, probably less, mostly plants, with friends/family.