Gerontologist Richard Weindruch and his team divided the monkeys into two "houses": One was fed a normal diet (we'll call them Gryffindors), while the other group (Slytherins) received 30 percent fewer calories along with supplements to ensure complete nutrition. The monkeys are now in their mid-20s, and the results show that 63 percent of the Slytherins are still alive compared to only 45 percent of the Gryffindors. The extreme dieters also appear to be in better shape, with less muscle and brain degeneration than their counterparts.

While the Slytherins seem to have won this particular House Cup, school's not out just yet. Explorations into caloric restriction on roundworms and mice have produced encouraging outcomes in the past, but not everyone is convinced human beings might also be able to ingest minimal food for maximal life. "Ultimately the results seem pretty inconclusive at this point," says Dr. Steven Austad, an aging expert at the University of Texas Health Science Center. "I don't know why they didn't wait longer to publish.''

Naturally, a few thousand people are already trying it anyway, following the method Roy Walford lays out in Beyond the 120 Year Diet: How to Double Your Vital Years. They claim to have more energy and a better sex life, which sounds pretty great, but there is a dark side: Just as Voldemort's dalliances with immortality leave him with a serpentine physique, people who practice caloric restriction must ingest vast quantities of carotenoids -- the substance that gives carrots their orange color. Eat enough beta-carotene and lycopene, and you'll take on an orange hue, too.

Could the key to long life be even easier to grasp than looking in the Mirror of Erised and wishing for a rock? Well, depends on your definition of "easier." Caloric restriction surely doesn't sound very pleasant. But neither does trying to wrestle the Sorcerer's Stone out of Voldemort's creepy claws. I mean, you don't want a nasty scar on your forehead and liver spots, do you?