Welcome to Running: A FEVER. I’m Michael Davis. This is a podcast about fitness, diet, and medicine. My goal is to live a long, healthy, happy, active life right up to the very end. And I do it by loving my life enough to make it last as long as possible.
In this series, we’re talking about how to stop or even reverse aging based on some scientific research in this specific field. Thus far, we’ve explored the idea of treating aging as a disease. We have also gone into the information theory of aging and studied several genes that are particularly important in the aging process and, more importantly, in the potential for reversing aging.
Today is all about caloric restriction and fasting: we’ll discuss the benefits of calorie restriction and intermittent fasting on longevity.
You know, longevity has been a part of this podcast for as long as I can remember. So, throughout this series, I’ve been combing the archives for episodes in which we discussed some of these topics. We’ve looked at fasting and calorie restriction before. In particular, look at episode 132. We also discussed it in 198. And there were other times, I’m sure.
Now, we want to talk about calorie restriction in the context of longevity gene activation. In his book Lifespan: Why We Age — and Why We Don’t Have To, David Sinclair writes, “There is no best diet; we’re all different enough that our diets need to be subtly and sometimes substantially different too.” It’s a variation of my mantra, “Become an expert in your own health.” Not everything we say here will apply to you, so take that to heart.
And we’re not talking about malnutrition or starvation. These are not paths to good health or longer life. Quite the opposite. What we’re talking about is intentionally eating less than we want. And it’s nothing new, really. Hippocrates recommended fasting as a treatment for certain illnesses in the fifth century BC. He believed that eating when you were sick was like feeding the disease.
A fifteenth-century nobleman, Luigi Cornaro, took on asceticism in his mid-thirties after a life of wine, women, and song. In what was perhaps the first self-help book, his First Discourse on the Temperate Life, he wrote, “I accustomed myself to the habit of never fully satisfying my appetite, either with eating or drinking, always leaving the table well able to take more.” He died at the ripe age of 100.
Alexandre Gueniot, a professor at the Paris Medical Academy at the turn of the twentieth century, was mocked for believing that hunger would lead to good health, but he lived to be 102.
In 1918, the same scientists who discovered vitamin A proved that female rats whose growth was stunted due to lack of food earlier in life lived longer than those that ate plenty.
A 1935 Cornell University study found that rats fed a diet of 20% indigestible cellulose lived significantly longer than those fed a normal diet. Studies continued throughout the century, confirming the idea that caloric restriction extends life.
Engaging the survival circuit directing the lives of sirtuins (as we talked about in the last episode, see RunningAFEVER.com/391), requires a delicate balance. Too much cellular trauma causes confusion and speeds up the aging process. However, just enough stress at the cellular level engages that survival circuit and increases lifespan. With calorie restriction, the key is to have just enough intake, but not too much.
In Okinawa, children get less than 2/3 of what children in mainland Japan get, and adults get 20% less. Okinawa is famed for the longevity of its residents, and a huge number of centenarians live there. It is one of Dan Beuttner’s “blue zones”. We reviewed his book The Blue Zones Solution in episode 128, which, of course, is available at RunningAFEVER.com/128. I’ll have all these links and more in the blog, which you can probably guess will be at RunningAFEVER.com/392.
Studies of humans in this regard is problematic given the danger of malnutrition, but observations have been made like the one on Okinawa. Another observational opportunity was found in the Biosphere 2 experiment, where a restricted diet resulted in lower body mass, blood sugar, and cholesterol levels.
Some practitioners of restrictive diets claim that it is difficult to deal with hunger initially but that you get used to it and aren’t hungry anymore. Intermittent fasting is another way to get this effect without long-term hunger and potentially dangerous consequences if you get it wrong. It’s become a bit of a fad in recent years, but it has been studied for a long time. A 1946 study found that rats that didn’t eat every third day lived 15-20% longer than the control group. And human studies are proceeding now.
A hormone found in the liver called IGF-1 has been found to relate to life expectancy. Mutations of this hormone and its receptor gene are found in females with centenarians in the family. The level of IGF-1 has an inverse relationship to longevity. One study found a reduction of IGF-1 in people who participated in the study by eating a calorie-restricted diet five days each month.
Fasting is also associated with some blue zones (places with statistically high numbers of centenarians) like Ikaria, Greece, where the strict practice of the Greek Orthodox fasting rules means adherents participate in some kind of fasting for half the year, and some fast even more often.
As you can see, there are several ways to do periodic fasting instead of long-term calorie reduction without going hungry and walking the thin line between what is too much and what is not enough. And importantly, we don’t have to change WHAT we eat, only HOW we eat. Of course, eating healthier makes us healthier, but we can still get the longevity benefits of caloric restriction without changing our diets.
So what about that diet? What should it consist of if we want it to be healthy and contribute to our longevity? One thing is food which is low in amino acids. That means, for the most part, getting our protein from plants. Studies show that consumption of meat and eggs causes increased rates of cardiovascular disease (the number one killer) and cancer, diseases we become more susceptible to as we age.
We briefly mentioned the enzyme mTOR in the last episode. Like sirtuins, it can put cells in survival mode and extend life, but only when reduced. The amino acid leucine can activate mTOR, and that disengagement of the survival circuit causes cells to multiply more. This is why leucine helps build muscle and is found in the protein shakes that bodybuilders consume before, during, and after working out. Those drinks could be causing us to age faster due to the deactivation of mTOR.
But some hunger is necessary. The longevity effect is not produced if you eat the same and burn off the calories by exercising. Nor can you eat low-calorie food that is filling. It’s about eating less, not the raw calorie count. We’ll explore exercise in more detail in the next episode.
However, reduced calories mean a reduction in body temperature. And this coldness has also been associated with longevity. We’ll go into more about the cold and longevity later in this series.
Some supplements can mimic the effect of caloric restriction, and we’ll discuss those in the upcoming episode on future medicines and technologies for reducing or reversing aging.
But for this episode, we’re just about done. I have a small favor to ask. If you’re watching this on YouTube, please like the episode. You can also subscribe, and if you want to be notified every time a new episode comes out, click the bell button for notifications.
I hope you’ve found this discussion enlightening and entertaining. It has made me even more curious about eating a low-calorie diet, whether long-term or short-term. And I think I’ll give it a try. Also, be sure to stay tuned for the next couple of episodes of the show, which I teased a little because calorie restriction also plays a role there.
So until next time, if you’ve got the fever, keep on keepin it burning. And if you don’t, catch the fever, and I will see you next time on Running: A FEVER.
References:
Sinclair, David A. and LaPlante, Matthew D. (2019). Lifespan: Why We Age — and Why We Don’t Have To. Atria Books.
https://www.britannica.com/topic/fasting
http://RunningAFEVER.com/391
http://RunningAFEVER.com/128
http://RunningAFEVER.com/392