thumb|Map of Ryukyu Islands.
The Okinawa diet describes the traditional dietary practices of indigenous people of the Ryukyu Islands (belonging to Japan), which were claimed to have contributed to their relative longevity over a period of study in the 20th century. although the male life expectancy rank among Japanese prefectures plummeted in the 21st century.
Okinawa had the longest life expectancy in all prefectures of Japan for almost 30 years prior to 2000. The relative life expectancy of Okinawans has since declined, due to many factors including Westernization.
Indigenous islanders' diet
thumb|The plate to the right is the national dish, gōyā chanpurū, made with bitter melon known as goyain.
The traditional diet of the islanders contained sweet potato, green-leafy or root vegetables, and soy foods, such as miso soup, tofu or other soy preparations, occasionally served with small amounts of fish, noodles, or lean meats, all cooked with herbs, spices, and oil. Although the traditional Japanese diet usually includes large quantities of rice, the traditional Okinawa diet consisted of smaller quantities of rice; instead the staple was sweet potato.
Another low-calorie staple in Okinawa was seaweed, such as wakame. Seaweed and tofu in one form or other were eaten on a daily basis.
Okinawans ate three grams total of meat – including pork and poultry – per day, substantially less than the 11-gram average of Japanese as a whole in 1950.
Okinawan health
In addition to their relative longevity identified in the mid-20th century, islanders were noted for their low mortality from cardiovascular disease and certain types of cancers. One study compared age-adjusted mortality of Okinawans versus Americans and found that, during 1995, an average Okinawan was 8 times less likely to die from coronary artery disease, 7 times less likely to die from prostate cancer, 6.5 times less likely to die from breast cancer, and 2.5 times less likely to die from colon cancer than an average American of the same age,
Research
In the 1972 Japan National Nutrition Survey, it was determined that Okinawan adults consumed 83% of what Japanese adults did and that Okinawan children consumed 62% of what Japanese children consumed. The food culture and presentation is preserved, passing low-calorie food from generation to generation.