Secrets of centenarians: 4 factors that influence who makes it to 100

By Joe Hannan | Fact-checked by Anastasia Climan, RDN, CD-N
Published March 6, 2023

Key Takeaways

  • Yes, genetics are integral to longevity. But research suggests that so are lifestyle factors such as how much we eat, when we eat, and how both may influence our gut microbiota.

  • These considerations may be critical given increasingly common struggles with overweight, obesity, and sedentary lifestyle.

  • Healthcare professionals can familiarize themselves with the latest evidence on the health factors that contribute to longevity.

What’s the secret formula for living 100 years? 

According to centenarian comedian George Burns, it was 20 cigars and six martinis daily and a distaste for fruits and vegetables. Actor Kirk Douglas, 103 at time of death, relied on more wholesome practices, such as daily activity and time with family. And Queen Elizabeth, who made it to 96, walked her dogs, rode horseback, and strolled the grounds of her estates.

Anecdotal evidence—and questionable lifestyle decisions—aside, what are the scientific facts of longevity? 

Lucky genes

First, let’s get the unfortunate truth out of the way: Some of longevity is a matter of luck. 

Research indicates that genetics[] determine about 25% of the differences in duration of human life. Certain polymorphisms located on the APOE, FOXO-3, and CETP genes are associated with long life.

This could explain, in part, why the first-degree relatives of centenarians are more likely to be in good health and to live longer lives than others.

Furthermore, if you have a centenarian parent, you’re more likely to be free of age-related disease at 70 than your peers. Siblings of centenarians also tend to live longer and develop age-related disease later in life, compared with their peers.

Don’t have a centenarian first-degree relative? Don’t despair. Not all people who become centenarians have these genetic variations. And despite what George Burns said, lifestyle factors still count toward longevity.

Caloric restriction

One 2022 meta-analysis, published in the International Journal of Molecular Sciences (IJMS), indicates that caloric restriction may be an important underpinning of longevity.

Researchers gathered relevant studies of international populations that looked at longevity factors such as nutrition, lifestyle, gender differences, blue zones, aging rate, and various others, in addition to caloric restriction.[]

After reviewing the evidence, researchers concluded that they cannot definitively say that caloric restriction leads to longevity. Part of the problem is that the data on nutritional habits and caloric intake of centenarians living in longevity blue zones is too inconsistent and/or incomplete to establish a causal link. Still, they believe there is a connection.

"Nutrition undoubtedly has profound effects on aging, and more certainly and importantly, on health span. "

Authors, IJMS

Their review contained numerous data points linking longevity to improved glucose handling, insulin sensitivity, and declines in plasma IGF1 levels—all of which are modulated by caloric restriction.

But, before you tell grandma to eat less, proceed with caution, the researchers noted.

“Higher frailty levels and increased anxiety were detected in experimental models of late-onset [caloric restriction] and similarly could happen in older people who are often at risk of undernutrition and sarcopenia, rather than of obesity, and in those who already have an appropriate diet and a normal weight,” researchers wrote.


There’s an emerging body of evidence suggesting that when we eat may be just as integral to longevity as how much we eat. 

Researchers summarized this evidence in a 2021 review article published in Nature Communications.[]

For example, the researchers highlighted how four short-term clinical trials have demonstrated that alternate-day fasting produces health benefits that are comparable with caloric restriction. Those benefits include weight loss, better lipid profiles, hypertension reduction, and improved insulin sensitivity. Furthermore, at least two studies have produced evidence that fasting may have cancer-fighting benefits and make cancerous cells more vulnerable to chemotherapy.

Additionally, the research suggests that sleep and eating may be inexorably linked, in terms of their potential impact on health and longevity.

“The timing of food intake relative to the natural increase in melatonin (which marks the beginning of night for each individual) is significantly associated with body fat percentage and body mass index,” the researchers wrote, adding that people with excess weight tend to consume most of their calories 1.1 hours closer to the onset of melatonin, compared with people who do not have excess weight.

"A periodic break in energy intake appears to improve multiple risk factors and, in some cases, reverse disease progression in mice and humans. "

Authors, Nature Communications

However, the researchers concluded that there’s more we don’t know than we know about how fasting affects longevity.

Gut microbiota

The more researchers uncover about gut microflora, the more apparent it becomes that these multitudinous microorganisms may be indispensable for human health. A 2020 review article published in Nutrients indicates that they may have an important role to play in longevity, too.[]

The researchers included 27 human studies to identify trends in gut microbiota diversity, composition, and functional features that may be associated with aging. 

Their work revealed that longevity may be linked to heightened flexibility and stability of gut microbiota, and that these features may be linked to inflammation.

“What might make the oldest-old adults unique is the ability to maintain (or possibly upregulate) anti-inflammatory activity despite a concomitant uptick of pro-inflammatory activity that occurs in all older adults,” the researchers wrote.

They noted that supporting this hypothesis observations of an increase in health-sustaining taxa that coincides with the production of short-chain fatty acids. Researchers postulated that while gut taxa are influenced by certain genetic factors, environmental factors such as diet also are influential. 

So perhaps encourage patients to lay off the George Burns diet after all.

What this means for you

Yes, genetics are undeniably important for longevity. But lifestyle factors that influence body composition and gut microflora also appear to be linked, research suggests. All findings indicate that lifestyle counseling remains an integral part of clinical care for promoting healthy lifestyle and longevity.

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