The best things have been said already in the other responses.
The high PREVENTABLE death-rate in the states is a combination of diet and lifestyle-meaning, for the greater part being sedentary(and, of course, smoking)
If you ever want to be truly terrified, bypass Stephen King, and read FastFoodNation,or Diet for a New America.
These detail where modern food comes from, and how it's produced,and both will change your eating habits.
More bad news: Almost all western nations are on a downward spiral of obesity and, at the same time, malnutrition, due in large part to convenience and fast-foods.
Fast-food vendors encourage us to eat more and larger amounts. This has added SIGNIFICANTLY to our intake of saturated fats and SUGAR.
Sugar is not benign. We might overlook it's evils because it's ubiquitous, but for another good scare read about what large amounts do to your overall health and mental health.