One hypothesis currently being investigated by researchers involves the traditional Japanese practice known as “hara hachi bu” (腹八分)—eating until about 80% full rather than continuing until feeling completely satiated.

This custom is particularly associated with the Okinawa region, which is known for its high number of centenarians. The concept is that stopping a meal before reaching total fullness naturally reduces caloric intake over time, without the need for restrictive dieting. While it does not fully explain weight differences between populations on its own, the habit is considered a contributing factor to the lower prevalence of obesity.

In addition to *hara hachi bu*, researchers highlight other aspects of the traditional Japanese diet that may work in tandem:

Smaller portion sizes.
Frequent consumption of fish, vegetables, seaweed, soy, and fermented foods.
Lower intake of ultra-processed foods.
Eating more slowly and chewing thoroughly, which can promote a sense of satiety.

It is important to note that no single habit is solely responsible for differences in weight management across populations. Factors such as genetics, physical activity, the food environment, culture, income, sleep quality, and access to healthy foods also play significant roles.

In summary, *hara hachi bu* is a scientifically promising practice because it can help naturally reduce excessive calorie consumption; however, researchers view its effects as part of a broader set of habits and characteristics inherent to the Japanese lifestyle.