Super Size Me is a deliciously amusing socio-culinary prank. The director and star, Morgan Spurlock, decided to eat nothing but food from McDonald's for 30 straight days. Without fail, he consumed three square meals -- roughly 5,000 calories -- a day, pigging out on Big Macs and Quarter Pounders, goopy salads and third-of-a-gallon Cokes; all the while, he monitored his weight and his health, arranging for a trio of physicians to chart his cholesterol, blood pressure, and so forth. Spurlock is tall, sandy-haired, and perpetually amused, with a slightly goofy handlebar mustache and, early on, a bit of a dainty stomach. On Day 2, he can't even keep down his double cheeseburger and supersize fries, vomiting it all up right on camera.
His tolerance grows quickly, though. As he travels around the country, recording each meal with straight-faced aplomb, ordering the supersize portion every time a cashier asks him if he'd like to, he doesn't deny that he digs the food. The deep-dish fun of ''Super Size Me'' is the way that Spurlock, for the sake of his documentary experiment, forces himself to do what every kid would love to do. He becomes the ultimate Mickey D's junkie, acting out the quest for instant -- and endless -- gratification until he's poised between craving and nausea. Along the way, he talks to a man who has eaten two Big Macs a day for decades with no adverse effects; he shows us schoolkids who can ID a picture of Ronald McDonald but not Jesus; he takes an eye-opening investigative detour into the way that school-lunch programs have been hijacked by junk-calorie marketers; he offers a graphic sequence (scored to ''The Blue Danube'') of an obese man's stomach-reduction surgery. ''Super Size Me'' is witty, gross, smart, outrageous, and so clever it just about pops. The movie lays bare the insidiousness of American fast-food culture by feasting on it in big, hungry bites.
Spurlock, it's clear, has taken a page or two from Michael Moore, but he's a far more benevolent muckraker. From the outset, he establishes that his true subject isn't McDonald's but addiction -- the vast, ruthlessly advertised national religion that fast food has become. At the beginning, a group of children jubilantly chant ''McDONald's! McDONald's! Kentucky Fried Chicken and a Pizza Hut!'' -- a pledge of allegiance they can truly believe in. Spurlock, like Moore, hates the way that corporations have exploited public weakness, and he shows sympathy (too much of it, I would say) for the recent lawsuits against McDonald's, but he's really laying the blame where it belongs: on us. Through it all, he casts his own Golden Arches odyssey as a perversely exciting adventure. What happens to Spurlock? He gains nearly a pound a day, and his liver turns to ''pâté.'' Yet the real news isn't so medical. In ''Super Size Me,'' we watch a man gorge on McDonald's until he gets sick of it (literally). He binges for our sins, and by the end you want to see him -- and all of us -- purged.