There is a whole body of scientific research dedicated to uncovering the lifestyles of people living in blue zones – areas of the globe where a higher proportion of people seem to live exceptionally long lives beyond the age of 100.

From Okinawa in Japan to the island of Sardinia in the Mediterranean, the seven blue zone regions have given rise to books, diets, documentaries and endless social media posts from “wellness coaches” delving into what it is about these places that lead people to live for so long.

What does the evidence say about blue zones?

In September the Australian researcher Dr Saul Newman, now at the Oxford Institute of Population Ageing in the UK, won an Ig Nobel prize after he uncovered the one critical factor key to longevity that all these regions have in common.

Terrible record-keeping, it turns out.

Newman tracked down 80% of people in the world claiming to be 110 years or older and found almost none of them have a birth certificate. His work is supported by a Japanese government review that found 82% of people aged over 100 in Japan were actually dead or couldn’t be located.

“Okinawans eat spam and KFC at high rates and are last in Japan for consumption of vegetables and sweet potato, and eat 41kg of meat a year,” Newman tells me. “They have the consistently worst BMI in Japan since 1975, including among the 75-plus-year-olds. This is not my data. It comes from the government of Japan, which surveys the people of Okinawa in the largest nutritional survey in the world.”

It turns out many of the components of diets such as the Mediterranean, Okinawan and other diets from blue zone regions have been cherrypicked and don’t reflect how those people are actually living.

What do experts recommend?

The physician and executive director at the George Institute for Global Health Australia, Prof Bruce Neals, says when you look at many of the recommendations made in articles about the blue zone lifestyle, “some of the suggestions are good for people”.

Eating more leafy greens and building movement into every day are important, evidence-based recommendations, he says.

“There’s also a bunch of stuff which is clearly just wrong,” he says, such as incorporating a certain amount of wine into the diet. Alcohol, for example, isn’t a part of any heart-healthy diet but is recommended by some blue zone diet advocates.

“But the things that really have made people live longer are environmental factors like having a sewerage system, having fresh water that’s readily available, and living in a society in which there is a reasonable degree of equity, peace and money,” Neal says. Vaccines, too, significantly add to life expectancy.

He says these are often factors beyond an individual’s control and come down to environment, government policies and wealth distribution.

And for people privileged enough to have access to all of these things? Are there ways to add more longevity?

The accredited dietician Dr Daisy Coyle says: “There is no specific formula for living to 110 years old, but we do know some factors that can influence longevity.”

A healthy diet, maintaining a healthy weight, avoiding smoking, exercising regularly, and limiting alcohol consumption are important. Managing stress, getting enough sleep, creating healthy connections and avoiding risky behaviours are important too, she says.

“Adopting these lifestyle habits can improve your chances of ageing well, but they don’t guarantee you’ll live to over 100.”

Genetics play some role, she says: “Not just in how long you live but also in your susceptibility to conditions like cancer and other diseases.”

A professor of healthy ageing at the University of Sydney’s Charles Perkins Centre, Prof Yun-Hee Jeon, has interviewed hundreds of older people living in rural and regional areas about their health and quality of life.

She says social connection is an incredibly important factor contributing not only to longevity but to quality of life and overall wellbeing.

“We’re not talking about having hundreds of social media followers,” she says. “We’re talking about having a couple of people actually close to where we live and having some sense of connection with them.”

Jeon says finding the perfect combination of lifestyle hacks to live longer may seem appealing but irks her. She says even people who do everything “right” will probably still get sick once they hit a certain point.

“About 80% of people aged 75 and older experience more than one health condition, but that doesn’t mean that they’re not ageing well, that they will all die soon, or that they can’t still have quality of life,” she says.

“What we have to do is accept that we will be exposed to health conditions in later stages of our lives, and so healthy life, to me, is about being able to adapt to those challenges and have some independence to do things you enjoy. I’m more interested in a life of quality, rather than living a longer life.”

• Melissa Davey is Guardian Australia’s medical editor. She has completed a master of public health and moonlights as a fitness instructor

• Antiviral is a fortnightly column that interrogates the evidence behind the health headlines and factchecks popular wellness claims