It's an American mainstay, present in all its cheesy, saucy goodness at almost every sporting event or social gathering. But as much as we love it, pepperoni pizza is junk. Delicious, greasy, gooey junk. Sure, Congress and others may argue that pizza contains something from each of the four food groups — grains, fruits and vegetables, dairy and meats — but when the grain is enriched and mixed with oil, the cheese is piled on and the meat is highly processed and full of salt and saturated fat, it's easy to see how pizza takes a turn from health food to junk food. But despite its bad nutritional rap, pizza is deliciously irresistible and not so awful when devoured in moderation. So enjoy the slices, just try to hold off on thirds.