Why are Americans so fat? It’s the corn.
In Michael Pollan’s book The Omnivore’s Dilemma: A Natural History of Four Meals, he uses an analysis of four conventional meals to explore the origins of fundamental components of the American diet: how food is grown via industrial farming, what organic food is about, and what it’s like to grow, and hunt, your own food. He focuses especially on the ominpresence of corn in the American diet, directly and indirectly (dairy from corn-fed cattle and eggs produced by corn-fed chickens). From a New York Times review of Pollan’s book:
Big agribusiness has Washington in its pocket. The reason its titans want to keep corn cheap and plentiful, Pollan explains, is that they value it, above all, as a remarkably inexpensive industrial raw material. Not only does it fatten up a beef steer more quickly than pasture does (though at a cost to ourselves and cattle, which haven’t evolved to digest corn, and are therefore pre-emptively fed antibiotics to offset the stresses caused by their unnatural diet); once milled, refined and recompounded, corn can become any number of things, from ethanol for the gas tank to dozens of edible, if not nutritious, products, like the thickener in a milkshake, the hydrogenated oil in margarine, the modified cornstarch that binds the pulverized meat in a McNugget and, most disastrously, the ubiquitous sweetener known as high-fructose corn syrup (HFCS). Though it didn’t reach the American market until 1980, HFCS has insinuated itself into every nook and cranny of the larder — in Pollan’s McDonald’s meal, there’s HFCS not only in his 32-ounce soda, but in the ketchup and the bun of his cheeseburger — and Pollan fingers it as the prime culprit in the nation’s obesity epidemic.