The remarkable longevity of Japanese citizens derives from a culture of temperance and reserve, eating habits that emphasize small portions of low-fat, high-protein foods, and a love of nature and the outdoors.

A typical meal in Japan is about half the size of an average Western meal and usually features fish, soy, vegetables, and tea, all linked to good health and long life. An old Japanese saying—Hara hachi bunme—instructs people to stop eating when you are 80 percent full. And a regional proverb counsels: "Eat like a crane," a bird whose pointed beak forces it to pick delicately at its food.

There are practical aspects to Japanese longevity as well. In most areas, parking a car is difficult and expensive, so a trip to the store is more likely to take place on a bike or on foot. And Japan's generally small homes mean people go out more for recreation and entertainment.

These and other common healthy habits, like tai chi, reiki, and yoga, give the Japanese one of the highest life expectancies in the world. A Japanese man can expect to live to age 78 and a woman to nearly 85. The average lifespan is 81.25 years, 16 years longer than the world average, and some 25,000 Japanese citizens are more than 100 years old.

Japan's notoriously exacting work ethic takes a toll on the overall health of the population, particularly men. And increased affluence has drawn many toward more Western habits and vices, like fast food, red meat, and cigarette smoking, which has increased the incidences of chronic disease and obesity and lost Japan its number-one spot on the world longevity list. The government is pursuing measures to curb this trend.