The mantra today if somebody wants to get healthier is “you need to eat more protein”.
If somebody feels fat, sick and tired, their first response is to start introducing new foods into their diet, but not necessarily at the expense of food they consume now; they just add more kale, turmeric, flax seeds, and so on on top of their existing caloric intake.
Even when most people say they are going to cut body fat, whether it’s for an upcoming fight, a race, or just for summer, they usually obsess over the balance of carbs and protein in their diet.
As far as we can tell, the last thing on many people’s minds when it comes to health, fitness, and longevity is eating less.
But there is a growing body of research suggesting that this is exactly what you should be doing if you want to get leaner, fitter, and live longer.
We’re going to focus on the relationship between caloric restriction and longevity here. We’ll cover how it affects fitness and body fat levels in other articles. There is more than enough to mention with regards to longevity!
What The Research Says
There’s no point waxing lyrical about caloric restriction. Let’s just dive right in and see what the scientists have to say about it!
Let’s start with one interesting study carried out on rhesus monkeys. Researchers at two universities found that when rhesus monkeys were fed a diet that was about 30% lower in calories than a control group, they tended to live longer. In fact, according to the researchers, at any one time of the study the monkeys undergoing caloric restriction had half the death rate of the control monkeys.
Interestingly, the incidence of age-related diseases was also far higher in control monkeys – those fed a regular diet – than in monkeys fed a restricted diet. Age-related diseases as defined by the researchers included “sarcopenia, osteoporosis, arthritis, diverticulosis, cataracts and persistent heart murmurs, in addition to age-related diseases including cancer, diabetes and cardiovascular disease”.
Yes, cardiovascular disease was also positively affected by caloric restriction: “Incidence of cardiovascular disorders was lower in CR monkeys than controls at UW. There was no apparent impact of diet on incidence of cardiovascular disease for monkeys at NIA; however, incidence for both control and CR monkeys was lower than UW controls.”
As interesting as these results are, studies done on monkeys can only tell us so much. The researchers did point out that, given the similarities in biology between rhesus monkeys and humans, the effect of fasting on the monkeys could be extrapolated onto humans. but we’d ideally like to see some human studies before we draw strong conclusions.
Thankfully, there are some really good ones now being published that hint at caloric restriction’s potential as a lifespan-increasing tactic.
This study, for example, was published in March 2018, and it points to a very powerful mechanism behind caloric restriction’s disease-postponing power.
According to the paper’s abstract: “The study found that calorie restriction decreased systemic oxidative stress, which has been tied to age-related neurological conditions such as Alzheimer’s and Parkinson’s diseases, as well as cancer, diabetes, and others.”
For example, there is strong evidence that prolonged caloric restriction significantly improves insulin sensitivity, which is thought to indirectly elongate lifespan.
There is also good evidence suggesting that regular caloric restriction reduces fasting glucose. This is thought to be a major factor in the ageing process through its effect on protein glycation. The mechanism or relationship is not thoroughly understood yet, but if you really want to maximize lifespan, then protein glycation might be something you want to try to mitigate.
We do also have some good human longitudinal data to look at, thanks to some epidemiological studies conducted on the good people of Okinawa, Japan.
The Okinawans previously ate a diet that was extremely high in nutrients, very low in energy-dense foods (meat and dairy), and most people reportedly ate a restricted diet (about 10-20% below daily caloric need depending on age).
Numerous studies have established that the people eating the traditional diet of Okinawa not only lived much longer than the people of mainland Japan (not to mention the West), but the incidence of disease among them was far lower too. Age-related diseases appeared much later in Okinawans, meaning that they not only enjoyed a longer lifespan, but also a far longer health span.
Some researchers note specific benefits that the Okinawan diet seemed to confer: “Hormone-dependent cancers including breast, ovary, prostate and colon and osteoporotic complications, such as hip fracture rates, are also less frequent compared to the west. Protective factors may include high anti-oxidant consumption, mainly flavonoids and carotenoids, through a high vegetable (e.g., onions) and soy intake.”
Interestingly for anyone looking to build lean muscle tissue, that same study also found that the people of Okinawa had a higher average serum DHEA level. DHEA is an important male sex hormone. Older Okinawan people clearly have a slower rate of depletion than Westerners or even mainland Japanese, meaning they will stay virile, strong and energetic for longer.
Should You Cut The Calories?
If your main goal is to live longer, it looks like the answer is a resounding “YES!”
Before you do though, it’s important to read the studies we’ve cited carefully and really take in what they’re saying.
First of all, they aren’t saying that caloric restriction can ward off all disease. It can’t stop you from ageing, and it can’t stop death. There’s no good evidence – as far as we know – that it can make a dint in serious diseases that have already manifested (it is sometimes used as a complimentary treatment on cancer patients, but it is not the primary treatment, which is surgery, radiotherapy, etc).
Second of all, the studies tend to show that a modest reduction in calories works when in conjunction with a nutrient-rich diet, a healthy lifestyle, and modest levels of activity. Starving yourself isn’t the answer, and caloric restriction will only make you sicker if your diet is already devoid of vitamins and minerals.
What we can draw from the studies is this: reducing your caloric intake, eating energy-poor but nutrient rich foods, and living an active lifestyle tend to elongate lifespan. Caloric restriction to the tune of about 20% seems to lower disease incidence across the board (when done right), without severely impacting fitness or hormone profile. In fact, in the Okinawan people, it seems to improve hormone profiles.