Just as important as putting truly nourishing substances into the body is avoiding substances that are bad for the body. The number-one "bad guy" on my list is high-fructose corn syrup. This stuff is killing Americans, making them obese as they suffer disease and even die due to MALNOURISHMENT. I am a meticulous label-reader when it comes to what I put into (or even ON) my body.
You probably know the basics: Avoid white sugar, white flour, artificial sweeteners, high sodium-content products, and products with high-fructose corn syrup. If you aren't familiar with this nutrition plan, I recommend checking out food-combining for better digestion and health. Suzanne Somers has a video called "Somercizing" that explains a lot about how to eat properly for best nutrition. Of course, one benefit of eating that way is that you will be the size your body is SUPPOSED to be -- not morbidly obese from all the crap "food" out there!