From Scientific American:
Morgan Spurlock’s “really great bad idea,” as it would later be called, came to him after a gluttonous Thanksgiving meal. Jeans unbuttoned, stomach engorged with turkey—and eyeing a second helping—the 32-year-old playwright noticed on the television news that two teenage girls from New York City were suing McDonald’s for allegedly making them fat.
“It was the dumbest thing I’d ever heard of,” Spurlock recalls thinking. Until, that is, a McDonald’s spokeswoman appeared on screen to deny any link between the chain’s food and the girls’ obesity, claiming that Big Macs, Chicken McNuggets and the rest of the gang were nutritious. “That was even crazier than the lawsuit,” says Spurlock, now 37. “If it’s so nutritious, I should be able to eat it every day.”
Against the better judgment of three doctors and the pleading of Alexandra Jamieson, his vegan chef girlfriend (now his wife), he enlisted himself as experimental subject, eating only McDonald’s fare, three meals a day, for 30 days. Super Size Me, the chronicle of his February 2003 “McOrgy,” became the eighth-highest grossing documentary in movie history, and is widely regarded as encouraging the end of the fast food “super size” era.
More here.