populations. The Mediterranean diet is widely believed to be one of the most healthful traditional diets, yet much of what we know about it is based on studies of people living in the 1950s on the island of Crete—people who in many respects led lives very different from our own. Yes, they ate lots of olive oil and more fish than meat. But they also did more physical labor. As followers of the Greek Orthodox church, they fasted frequently. They ate lots of wild greens—weeds. And, perhaps most significant, they ate far fewer total calories than we do.