1. They make it cheaper to buy "meals" than a la carte items.
2. They use fake smells to make you think you're hungry when you aren't.
3. They change the meaning of basic words, like "Large."
4. They know that seeing a food "can stimulate unplanned consumption" even when you're not hungry.
5. They keep adding cheese.
6. They turned cup holders into meal holders.
7. Their restaurants are designed to make us eat too much too fast.
Everything about a fast food restaurant encourages us to clean our trays quicker than we normally would. The color red, the bright lighting, the clatter of noise, and the nonstop smells all make us think we're hungrier and in more of a rush than we really are. (And as we all know by now, when we eat too fast, we eat too much.)