No country has embraced the movement toward commercialized, prepackaged food as much as the United States.

Americans eat 31 percent more packaged food than fresh food, and they consume more packaged food per person than their counterparts in nearly all other countries. A sizable part of the American diet is ready-to-eat meals, like frozen pizzas and microwave dinners, and sweet or salty snack foods.

"Americans tend to graze rather than sit down and eat a full meal, so the food is tailored for convenience," said Mark Gehlhar, who has studied global food consumer preferences at the Economic Research Service of the Agriculture Department. "And Americans do not seem to be as discerning about quality."

T. Colin Campbell, a nutritionist at Cornell University, said that "there is a lot of money tied up in the industry because it is profitable for companies to make these foods." He added that "Processed foods contain large amounts of fat, salt and sugar, and Americans have become addicted to them."