Hara hachi bu: the ancient Japanese rule for not gaining weight

Hara hachi bu (腹八分) is a traditional Japanese principle that literally means “80% stomach .” The idea is to stop eating when you feel about 80% full , rather than waiting until you are completely full.

This practice was studied in Okinawa, a region known for the high longevity of its population.

Hara hachi bu is based on the fact that the feeling of satiety isn't immediate: it takes about 15–20 minutes for the brain to fully register that the stomach is full. By stopping a little before complete satiety, it's easier to avoid overindulgence. Eating until you feel "fairly satisfied," rather than completely full, reduces the risk of overindulging without requiring you to count calories.

In practice this means:

• eat slowly;
• take small bites and chew well;
• pay attention to hunger and satiety cues;
• stop when hunger is virtually gone, even if you could continue eating.

Research suggests that this habit can help reduce calorie intake without following a strict diet; help maintain a healthy body weight; improve blood sugar control after meals; and reduce the risk of eating out of habit or boredom.

Obviously, hara hachi bu is associated with other fundamental and healthy eating habits of the Japanese people: a diet rich in vegetables, legumes, fish and moderate portions, as well as regular physical activity.

The result is that Japan is one of the high-income countries with some of the lowest obesity rates in the world.

According to data from the Organisation for Economic Co-operation and Development and the World Health Organization, in most developed countries, adult obesity exceeds 20–30% of the population; in Japan, the prevalence of obesity (generally defined as a BMI ≥30 according to the international standard) is around 4–6% , one of the lowest among OECD countries.

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