Boredom for some, comfort for others, addiction for most.
The Average American diet consumes a lot of gluten and processed foods. Processed foods have a lot of sodium, which increases the need to want to eat. On top of it, the food colorings, preservatives, excessive use of corn and corn products in them, have addicting properties.
Gluten acts as an opiate in the brain, and can be addicting as well. It triggers the same receptors in the brain as morphine, and can cause the same cravings as morphine addictions. As mentioned before, corn can do similar things.
You can read a little bit more in depth about gluten in my review on Wheat Belly here
and I have more information on corn in my Morality of Food Series: