I hear it all the time: why not just eat a diet like the Okinawans, the healthiest and longest lived people in the world? Traditionally they ate rice, tofu, and almost no meat! Unfortunately after WWII Americans introduced bad foods like pork and now disease rates are increasing.
That's the conventional narrative at least. Honestly, I'm not sure about the Okinawan diet. Most of the people discussing it are Americans with some sort of ax to grind. I would love to hear some Okinawan voices tell us what they actually ate, but those are few and far between.
Americanized nonsense "Okinawan Diet"
The picture that is painted from the actual studies available is pretty murky, but shows that what is being promoted as an Okinawan diet is cultural misappropriation for profit, with American nutritionists making $$$ passing off what ends up being a Mediterranean diet with rice as the secrets of Okinawan elders.
The real traditional diet seemed to consist of yams, goat, pork, tofu, seaweed, and seafood harvested from the island. It seems like it was pretty similar to the diet of Kitava. After the devastation of World War II, importation of food increased and oils, sugar, flour, white rice, and other processed foods became staples. The narrative of fat consumption increase only takes statistics starting from World War II, so we really don't have much of an idea of how much fat was in the traditional diet.
We do know the the consumption of traditional foods like raw goat, yams, and seaweed decreased dramatically. Also, that domestic meat production didn't really change much after WWII and much of that increase was probably recovery from devastation of the war. The increase of meat consumption came mostly from imported animals that were probably factory-farmed...or SPAM, which is now hugely popular there.
It does seem that their traditional diet was high in carbohydrates from yams, but its nonsense make up an Okinawan Diet plan including foods that are nothing like what pre-WWII Okinawans consumed such as whole grain bread, olive oil, soy milk, apples, and yogurt. The traditional Okinawan diet doesn't seem to be far from my own paleo diet, except for the soy . Fortunately, the harmful effects of that can be mitigated by fermentation. I occasionally consume some fermented soy since I am an Asian food enthusiast and I adore the taste of miso and ssämjang. Yam are controversial on the paleo diet, but personally I enjoy them without ill effects. I would say my own paleo diet is heavily influenced by Japanese cuisine and benefits from it tremendously. I could never tolerate a diet of just eggs and ground meat...I'm too much of a foodie and an omnivore for that!
Here is a recent paper on the importance of the yam, kombu, and pork offal in Okinawa. Paleo dieters could definitely benefit from the consumption of kombu, which is rich in iodine, and pork offal (feet, ears, blood, intestines), which is delicious and contains many important nutrients. The problem with this paper is that they assume that people threw away pork fat...I don't know of any agrarian culture that exhibits that kind of waste. They say akunuki is removal of fat, but it also seems to mean removal of astringent taste.
Speaking of Japan, I was just reading this editorial by Swedish scientist Uffe Ravnskov:
In a study of Japanese migrants in the United States the cultural upbringing was the strongest predictor of coronary heart disease. Those who were brought up in a non-Japanese fashion but preferred the lean Japanese food had a heart attack almost twice as often as those who were brought up in the Japanese way but preferred fatty American food.4
I think it's possible that the issue here was that they thought fat wasn't traditional for Japan, but it sheds light on the fact that fat doesn't seem to cause heat disease.