This article in GoAnimal.com suggests that a diet high in real food and low in "food products" (heavily processed foods) will leave you much healthier. It points to the development of hydrogenation and trans fats, and high fructose corn syrup, as the "twin horsemen of our metabolic apocalypse."
How do You Tell the Difference?
They suggest that food can be identified because it is:
While "food products" are:
Picking Your Food
They also make a number of further suggestions to help you make the distinction:
The basic premise of this article is right on the target. Your body was designed to eat natural foods as they are found in nature, not artificial substances that are created in a lab. They correctly point to trans fats and high fructose corn syrup as two of the unnatural scourges that have created an epidemic of degenerative diseases in the modern world. I would also add artificial sweeteners and the vast numbers of additives, preservatives and artificial flavorings to the list.
Those are the foods that the human body adapted to over hundreds of thousands of years, long before fairly recent (in evolutionary terms) farming techniques loaded our diet with simple sugars and carbohydrates. If you really want to be healthy, reduce or eliminate grains and sugars from your diet, and eat the foods you evolved to eat.