Extending life has always been an endeavor thatâ€™s captured the human imagination. Our written history is replete with folk tales and urban legends about rituals, remedies, and spiritual practices that heal our wounds, maintain our vitality, and keep us drinking from the fountain of youth. Many religious dogmas are centered around the goal of securing our place in heaven. Extending life beyond death.
In the centuries since, our priorities havenâ€™t changed. We spend an increasingly larger share of our national GDP on life-extending procedures and medications, and the 20th century had more than its share of technologists and visionaries dreaming up scenarios where weâ€™d use scientific innovation to increase our life span to infinity and beyond.
Â Does Caloric Intake Affect Longevity?
Of course philosophers and poets have had plenty to say about whether or not such a state of being is preferable or not. However, on the margin it doesnâ€™t change the preference most of have towards extending our life. That is, on most days itâ€™s better to be alive than dead.
The science of life extension has sprawled out into an eclectic mix of scientific disciplines. Genomics, bio-informatics, cell biology and other branches of the life sciences have taken their turn at hacking the human genome. These attempts have had varying degrees of success, but over the decades one discipline has enjoyed a surprising amount of success over the others: nutrition. Certainly not the sexiest of fields, but nutrition has the benefit of studying the most basic interaction our bodies have with the environment around us: the food we put in our mouths. And when it comes to food and expanding life spans, a clear best practice has emerged over the last 50 years: donâ€™t eat very much of it.
Caloric restriction is the act of continuously depriving the body of calories compared to some baseline that itâ€™s used to. On-going caloric restriction has shown to be remarkably robust at extending life spans, delaying the onset of age related diseases and maintaining metabolic balances.
Research on caloric restriction began in the 1950â€™s when scientists began to starve rats to study its effect on their observed behavior and physiological health. To Â their surprise, the starved rodents had improved mental agility, hormonal balances, and health in old age. They lived a lot longer too. Research began to study the effect in other animals and the results were consistent: fewer calories meant longer lives. From bacteria like C. elegans, to fruit flies, dogs and our closest primates, caloric restriction always seemed to extend time on earth.
[box type=”note”]In fact, the correlation has become so strong that the burden of proof has reversed itself. Scientists are now challenged to find an example where caloric restriction doesnâ€™t extend life and improve health.[/box]
Of course, there are problems when we apply this finding to humans. Weâ€™re not fruit flies or lab rats, and we canâ€™t starve â…“ of the population their whole lives and wait and see what happens. However, a number of studies that indirectly measure the effect of caloric restriction suggest the results are the same for humans as they are for the rest of the animal kingdom.
For one, our closest relative in the animal kingdom have shown remarkable benefits when given a calorically restricted diet. A study published in the European Journal of Clinical Nutrition found that rhesus monkeys that were fed 30% less calories than a control group aged more slowly, had lower blood pressure, increased insulin sensitivity, and less warning signs of cardiovascular disease and cancer. This type of finding is particularly remarkable because rhesus monkeys that are malnourished develop â€œlifestyle diseasesâ€ in a manner thatâ€™s very similar to humans.
Perhaps the strongest case for the benefits of caloric restriction in humans is the study of the most prolific group of centenarians on the planet: the Okinawans. Okinawa is a region in the south of Japan that became famous when researchers discovered they had a much higher portion of people living beyond 100 than other parts of the world. A flurry of research about their lifestyle quickly followed.
One fact that soon became apparent is the Okinawans had a diet that was quite distinct from the rest of the world. Their typical meals consisted of lots of fruits and vegetables, water-based soups, and had little meats or calories. Compared to the rest of the world they had a diet that was both calorically restricted and nutrient dense. In fact, it was found that the typical Okinawan consumed 40% fewer calories than the typical American.
Furthermore, clinical studies have shown that caloric restriction causes physiological changes that are dramatic and rapid in people who adopt the habit in the middle of life. A paper published in the New York Academy of Sciences found that people who reduced their caloric intake by 20% had reduced blood pressure and cholesterol, lower blood sugar, and increased insulin sensitivity after 2-6 years. Even after six months, subjects displayed favorable biomarkers. Caloric restriction might be the reason women live longer than men. On average they consume 25% fewer calories and live 5 years longer.
Of course, this sort of news should not come without its caveats. The most important detail to take note of is that caloric restriction has only been shown to be effective when nutrients are not sacrificed as well. So only snacking on sweets and fast foods will not have the desired effect. Neither will anorexia or bulimia.
In fact, several studies have suggested that itâ€™s the nutrient density of reduced calorie diets and not the calories themselves that have the life-extending effects. Furthermore, extreme dieting has shown to have the opposite effect of a calorie restricted diet. After going on a radical diet people have a tendency to binge eat and lose any gains they have made after extreme fasting.
[box type=”important”]So take this news with a bit of caution. The benefits of reducing your calories while still maintaining high levels of vital nutrients like vitamin A, B, C, D and anti-oxidants and phyto-chemicals seems to have remarkable effects on the human body. However, this is not the same thing as fad dieting, starvation, or an endorsement of adopting an eating disorder. Rather, itâ€™s an embrace of the advice Michael Pollan gives his readers in his book the Omnivoreâ€™s Dilemma: Eat food, not too much, mostly plants.[/box]
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