Okinawa, an idyllic Japanese island known for its stunning beaches and sunny landscapes, also boasts a population of some of the world’s longest-living people. Research into their longevity has pointed towards a simple three-word mantra that may well be a key factor.
Before each meal, locals say “Hara hachi bu”, which translates to “Eat until you are 80 percent full”. Longevity expert, Dan Buettner, who has studied the health practices of Okinawans, shared his insights during a conversation with Dr Craig Willcox, co-author of ‘The Okinawa Program’.
He described the thinking behind this eating habit: “Undereating, as the theory goes, slows down the body’s metabolism in such a way that it produces fewer damaging oxidants – agents that rust the body from within.”
Expanding on these ideas in his book ‘The Blue Zones secrets to living longer’, Buettner explained: “Unlike most Americans, who keep eating until their stomachs are full, traditional Okinawans stop as soon as they no longer feel hungry.”
He also suggested an additional benefit of this practice by adding: “It provides a helpful nudge to stay fit. The 20 percent gap between not being hungry and feeling full could be the difference between losing weight and gaining it.”
The 80 percent rule, known as ‘Hara Hachi Bu’, has been the subject of extensive research in recent times. Health expert Jayanta Kumar Das from the National Institute of Health highlighted its potential benefits beyond longevity, suggesting it could also lead to healthier aging.
He stated: “Our research indicates that moderate calorie restriction in humans has the potential to influence various biological pathways [that], when activated, may positively contribute to healthy aging and resilience of muscle tissue.”
But the advantages don’t stop there.
Enhanced enjoyment at meal times
Enhanced mealtime enjoyment is another perk of this practice, according to Japanese-British dietitian Kouka Webb. She believes that the ‘Hara Hachi Bu’ method can increase the pleasure derived from eating by encouraging people to savour the flavours, textures, and scents of their food.
Webb shared: “By focusing on the flavors, textures, and aromas of the food, people may get more satisfaction from their meals,” adding, “I also find that for me, hara hachi bu makes me more aware of what and how often I’m eating, which in turn makes the whole dining experience more enjoyable.”
Help with weight loss
Moreover, Webb suggests that this lifestyle approach promotes mindful eating and portion control, which can aid in weight loss “without the need for strict calorie counting or eliminating certain food groups”. Supporting this, a 2018 review in the journal Current Obesity Reports concluded that mindful eating is a significant factor in managing weight and addressing obesity.
May help with digestion
The practice may even improve digestion, rounding off a list of potential health benefits associated with the ‘Hara Hachi Bu’ principle.
Dietitian Asak Miyashita warns that eating until you’re completely full could slow down digestion and negatively impact metabolism, putting a strain on organs such as the stomach, intestines, pancreas, kidneys, and liver. On the other hand, Webb suggests that by eating until 80 percent full, individuals may experience less discomfort and reduce strain on their digestive system.
The Cleveland Clinic also notes that overeating can lead to indigestion and stomach pain.
Could help lower risk of chronic diseases
A 2024 study indicates that Okinawans, who are known for having significantly fewer illnesses like diabetes, heart disease, and cancer, follow the 80% rule, although it’s unclear how much this principle contributes to their lower disease rates.
While many admire the Okinawans for their food consumption, it’s believed that what they eat, particularly imo or purple sweet potato, significantly boosts their health. Described by Buettner as one of the “healthiest foods on the planet”, this superfood is rich in nutrients including vitamin C, fibre, carotenoids, flavonoids, and slow-burning carbohydrates.