This is one of my favorite articles from the New York Times. The politics of agriculture and the root causes of the obesity epidemic are spelled out better than I've ever seen prior or since.
"The (Agri)Cultural Contradictions Of Obesity" By Michael Pollan

"Nixon ordered his secretary of agriculture, Earl (Rusty) Butz, to do whatever was necessary to drive down the price of food.
Butz implored America's farmers to plant their fields ''fence row to fence row'' and set about dismantling 40 years of farm policy designed to prevent overproduction.

Cheap corn, the dubious legacy of Earl Butz, is truly the building block of the ''fast-food nation.'' Cheap corn, transformed into high-fructose corn syrup, is what allowed Coca-Cola to move from the svelte 8-ounce bottle of soda ubiquitous in the 70's to the chubby 20-ounce bottle of today. Cheap corn, transformed into cheap beef, is what allowed McDonald's to supersize its burgers and still sell many of them for no more than a dollar. Cheap corn gave us a whole raft of new highly processed foods, including the world-beating chicken nugget, which, if you study its ingredients, you discover is really a most ingenious transubstantiation of corn, from the cornfed chicken it contains to the bulking and binding agents that hold it together."