The Okinawa diet can refer either to the traditional diet consumed by the native peoples of the Ryukyu Islands (Okinawa is the largest and best known of these), or to a commercial online weight loss diet that was published in the early 2000s. In either case it is basically a low-fat, low-calorie diet.
The Satsuma potato, a type of sweet potato (Ipomoea batatas), was introduced to the islands by the Japanese in the seventeenth century. Okinawans regarded this plant as a stable source of food that eased the recurrent threat of starvation. Satsuma potatoes were a staple of the Okinawan diet up through the end of World War II, when they were supplemented with rice, which became more readily available in the 1950s. The potatoes were usually eaten steamed, with the leaves of the sweet potato vine stir-fried and eaten in soups. They were difficult to preserve for long periods of time, so the Okinawans often converted them to potato starch, which could be used in the preparation of other dishes.
The commercial Okinawa diet was developed by three gerontologists, who also head the Okinawa Centenarian Study (OCS), an ongoing research project funded by the Japanese Ministry of Health that began in 1975. The study is investigating the reasons for the relatively high number of centenarians among the Okinawan population. Although genetic factors are thought to account for 30%–50% of longevity in any human group, diet and nutrition, high levels of physical activity, not smoking, and effective stress management are all thought to play a part. The traditional lifestyle of Okinawans, including their diet, is thought to contribute to their low rates of cancer, dementia, cardiovascular disease, and osteoporosis compared to their Western counterparts. The three members of the OCS research team began to publish popular diet books for Westerners based on the traditional Okinawan diet in 2001.
Another reason for the heavy use of vegetables in traditional Okinawan cuisine is the belief derived from Traditional Chinese Medicine (TCM) that food in general and vegetables in particular have a tonic or medicinal quality. Even in contemporary Okinawa, it is customary to thank those who have prepared and served a meal by saying “Kusuinatan,” which means that the food is like medicine because it has been good for the guest's body. Certain herbs and vegetables such as bitter melon, fennel leaves, green mustard, and “long-life grass” are used in Okinawa to treat ailments ranging from eczema and diarrhea, to coughs and colds.
The traditional Okinawa diet contains only 25% of the sugar and 75% of the grain of the average Japanese dietary intake. It also contains less fish than is customary in the Japanese diet—less than half a serving per day on average. The Okinawa diet includes very little meat, with the exception of pork, and almost no eggs or dairy products. The creators of the commercial Okinawa diet plan maintain that there is a connection between the low caloric density of the traditional foods used in Okinawan cooking and the long life span of many of the islanders.
The central concept of the commercial Okinawa diet is caloric density (CD)—that is, the number of calories per gram of food. The importance of this concept in the plan is to help people avoid feeling overly hungry by eating larger amounts of foods with low CDs and smaller amounts of foods with high CDs. The commercial diet plan classifies foods into four categories according to caloric density:
The recipes included in The Okinawa Diet Plan, the most recent book published by the originators of the diet, are intended to accommodate strict vegetarians as well as meat eaters. There are three styles of cooking represented in the recipe section of the book: Western, traditional Eastern, and fusion (a combination of the two).
The question is whether CR has the same effect on longevity in humans. One difficulty in answering this question is that several decades would be required to test the effects of CR in human subjects as they age. Another difficulty is that short-term studies of CR in humans have largely involved subjects who were overweight to begin with; it is not yet clear whether CR would be equally beneficial in normal-weight subjects used as controls. In addition, the exact amount of calorie intake and body mass related to optimal health and maximal longevity in humans has not been determined. There is some evidence that people who are underweight or have a slender body build may actually develop health problems from a CR diet.
The goals of the Okinawa diet are overall weight loss, loss of body fat rather than lean body tissue, and long-term weight management—although the originators of the commercial diet claim that it also contributes to a longer life span. This claim is based on the fact that Okinawa has one of the world's highest proportions of centenarians—people who have reached age 100—in its general population. It is theorized that the longevity of Okinawans is related to the calorie restriction (20% fewer calories than the usual Japanese diet) of their traditional eating habits. The Okinawa diet is intended to be a lifelong way of eating rather than a quick weight-loss diet for temporary use.
Most people who stay on the commercial Okinawa diet will lose at least some weight. There is little data available on the number of people who remain on the diet for longer than the eight-week plan contained in the popular books, and no provisional reports of its effects on their overall health.
The most important precautions for the Okinawa diet, as for any other diet intended for weight control or diabetes management, are making sure that the diet is based on accurate medical information and sound nutritional advice, and that it includes foods and recipes that the individual patient enjoys, for the sake of long-term compliance. People interested in using a calorie-restriction diet or any other diet plan for weight loss should first consult their primary care physician. People already at a healthy weight do not need to undergo calorie-restriction diets and may even experience adverse side effects.
People on any calorie-restriction diet run some risk of inadequate vitamin and mineral intake. In addition, some people find that this type of diet triggers episodes of binge eating, so that any weight loss may be undone by periodic food binges.
There are relatively few research studies of the Okinawa diet. With regard to the association between calorie restriction and longevity, there is no consensus among researchers as to whether and to what extent animal studies of CR are applicable to humans. One finding that has emerged is that long-term CR diets do not appear to reduce the appetite for food; animals on a calorie-restriction diet are continuously hungry. As the authors of one article state, “the feasibility of restricting [food] intake in humans for many decades without long-term support is questionable.” Another question is whether the supposed benefit of CR to human longevity applies to people who were obese when they began the diet or only to people who have always maintained a normal weight.
An additional question that applies to the Okinawa diet, as well as to other traditional diets, is whether eating habits can be separated from such other factors that affect longevity as lifestyle, genetics, and the human and geographic environment.
See also Anti-aging diet .
Willcox, Bradley J., D. Craig Willcox, and Makoto Suzuki. The Okinawa Diet Plan: Get Leaner, Live Longer, and Never Feel Hungry. New York: Clarkson Potter, 2004.
Willcox, Bradley J., D. Craig Willcox, and Makoto Suzuki. The Okinawa Program: How the World's Longest-Lived People Achieve Everlasting Health—and How You Can Too. New York: Clarkson Potter, 2001.
Willcox, Bradley J., Makoto Suzuki, and Craig D. Willcox. The Okinawa Way: How to Improve Your Health and Longevity Dramatically. Williamsburg, VA: Mermaid Books, 2001.
Gavrilova, Natalia S., and Leonid A. Gavrilov. “Comments on Dietary Restriction, Okinawa Diet and Longevity.” Gerontology 58, no. 3 (April 2012): 221–23.
Hokama, Tomiko, and Colin Binns. “Declining Longevity Advantage and Low Birthweight in Okinawa.” Asia-Pacific Journal of Public Health 20, suppl. (October 2008): 95–101.
Le Bourg, E. “Dietary Restriction Studies in Humans: Focusing on Obesity, Forgetting Longevity.” Gerontology 58, no. 2 (2012): 126–28.
Redman, Leanne M., et al. “Effect of Caloric Restriction in Non-Obese Humans on Physiological, Psychological, and Behavioral Outcomes.” Physiology and Behavior 94, no. 5 (August 6, 2008): 643–48.
Speakman, J. R., and C. Hambly. “Starving for Life: What Animal Studies Can and Cannot Tell Us about the Use of Caloric Restriction to Prolong Human Lifespan.” Journal of Nutrition 137, no. 4 (April 2007): 1078–86.
Willcox, B. J., et al. “Caloric Restriction, the Traditional Okinawan Diet, and Healthy Aging: The Diet of the World's Longest-Lived People and Its Potential Impact on Morbidity and Life Span.” Annals of the New York Academy of Sciences 1114 (October 2007): 434–55.
Willcox, D. C., et al. “The Okinawan Diet: Health Implications of a Low-Calorie, Nutrient-Dense, Antioxidant-Rich Dietary Pattern Low in Glycemic Load.” Journal of the American College of Nutrition 28, suppl. (August 2009): S500–S516.
“The Okinawa Diet Food Pyramids.” http://okinawadiet.net/okinawa_diet/okinawa_diet_food_pyramid.html (accessed April 13, 2018).
Okinawa Centenarian Study (OCS), (808) 524-4411, http://www.okicent.org/index.html .
Okinawa Research Center for Longevity Science (ORCLS), 1-27-8 Ahacha, Ste. 202, Urasoe, Okinawa, Japan, 901-2114, +81 98 874-7330, ORCLS@nirai.ne.jp, http://orcls.org/index.php .
Pacific Health Research Institute (PHRI), 3375 Koapaka St., Ste. I-540, Honolulu, HI, 96819, (808) 524-4411, Fax: (808) 524-5559, email@example.com, http://www.phrei.org/index.html .
Rebecca J. Frey