Wikipedia wrote:
Generally, the traditional diet of the islanders is 20% lower in calories than the Japanese average and contains 300% of the green/yellow vegetables (particularly heavy on sweet potatoes). The Okinawan diet is low in fat and has only 25% of the sugar and 75% of the grains of the average Japanese dietary intake.[2] The traditional diet also includes a relatively small amount of fish (less than half a serving per day) and somewhat more in the way of soy and other legumes (6% of total caloric intake). Almost no meat, eggs, or dairy products are consumed.