The ’80 percent rule’ or ‘Hara Hachi Bu’ dietary practice may help you live longer
Lauren Haughey Lifestyle and Money Reporter
11:01, 27 Jan 2026Updated 11:04, 27 Jan 2026
Experts have delved into a simple Blue Zone dieting practice (stock image)(Image: Mirjana Pusicic via Getty Images)
On the face of it, Italy, Japan and Costa Rica may seem worlds apart, yet they share a remarkable link. These nations are home to three of the world’s six rare ‘Blue Zones’ where residents are said to have a significantly greater chance of reaching 100 than average US citizens.
But if you don’t call these longevity hotspots home, there’s no need to worry. Experts recently delved into a potentially pivotal ‘secret’ for residents’ longevity, which focuses on an approach called the ‘80% trick’ or ‘Hara Hachi Bu’.
This eating principle won’t appeal to anyone fond of tucking into three substantial meals each day. It is believed that some Blue Zone residents might only have a single small meal in the evening, intentionally stopping at about 80% fullness, which is why the practice is named as such.
No foods are strictly forbidden with the ‘80% rule'(Image: istetiana via Getty Images)
This method is believed to ward off the familiar sluggish sensations that can follow excessive eating, whilst also helping locals maintain their energy levels throughout the day. According to researcher Dan Buettner, the technique originated in Okinawa, one of Japan’s smallest islands.
As noted by the Mirror in 2024, he explained: “The secret to eating in moderation in the long run is emulating the environment and habits of the Okinawan people. There is a significant calorie gap between when an American says, ‘I’m full’ and an Okinawan says, ‘I’m no longer hungry’.”
Previous studies suggest that Okinawans typically sustain a ‘calorie deficit’, consuming around 1,900 calories instead of the usual 2,000 to 2,500, which is associated with a reduced risk of age-related diseases.
Dr Deborah Lee, a GP at Dr Fox Pharmacy, shares similar sentiments. She revealed to the Mirror that consuming less food could potentially help slow down the ageing process.
“Imagine what 80% of your meal would look like, and aim to leave 20% behind,” she said in a past interview. “Calorie restriction is believed to slow the ageing process. Eating less lowers the metabolic rate.
Okinawa in Japan (pictured) hosts one of the world’s Blue Zones(Image: @ Didier Marti via Getty Images)
“With less metabolic processes underway, less oxidation is taking place. Oxidative stress probably underpins the development of many of the chronic diseases we see today – heart disease, cancer, type-2 diabetes and dementia.”
Dr Lee recommended that taking your time whilst eating can assist in following the 80% principle. Scientific evidence arguably supports this, with a 2012 study showing that eating at a slower pace is connected to greater fullness and reduced hunger pangs between meals.
She continued: “Nutritionists believe that when you look at your plate, if you eat mindfully, eating slowly and chewing every mouthful thoroughly, you can feel satisfied by eating only 80% of that is on your plate.
“The diet has many benefits. You don’t have to count calories, and no foods are absolutely forbidden. It can fit in with your work and social schedule. You are still eating large amounts of healthy foods and getting good nutrition.”
For the latest money-saving tips, shopping and consumer news, go to the new Everything Money website
AloJapan.com