What makes humans unique? There are many answers that can and have been offered. My own dietary experimentation, from paleo to keto to carnivore, has led to certain thoughts. After two months of carnivory (and before reintroducing plant foods), I ended it with an extended fast, three days to be precise, as inspired by Siim Land. There is something impressive about fasting, far beyond its intermittent variety. Yes, ketosis is involved, but lengthening the fasting state steps it up to a whole other level, specifically to be scientific what is called autophagy along with stem cell activation. With autophagy, your body cannibalizes damaged and dead cells in order to build entirely new cells, including in the brain, and in the process of three days of fasting every cell in your immune system will be replaced. That is pretty kick ass!
More basically, fasting simply feels good or it can, assuming one isn’t sick or stressed. It’s not as hard as one might think, assuming one begins it in a state of ketosis and fat-adaptation. That is the way it has been for me, in the several extended fasts I’ve done. I’ve even done part of the time in dry fasting, that is to say not even water. With fasting, energy doesn’t necessarily decline and sometimes there is a boost of energy, specifically when ketones kick into high gear. And even without water, the body shifts into a different mode and one doesn’t get thirsty, at least not for many days (breathing through one’s nose helps as well), since the body stores water similar to how it stores fat. Fasting has been a practice among probably every traditional society that has ever existed, from early Native Americans to early Europeans, and is found in diverse religions, from Buddhism to Christianity — fasting only became uncommon since vast food surpluses were created in recent generations.
I’ve done fasting in the past, but I always limited myself to one-day fasts. It was never difficult and, even though few people ever do it, I never considered it an impressive feat of personal strength and willpower. It simply meant not eating food for a time. More interesting on a personal level was a different kind of fasting. Maybe a couple of decades ago, I got into the habit of jogging before eating and I would sometimes go for hours. I never lacked energy and, if anything, I had more energy than before I began. A strange side effect was that my hunger also decreased for the rest of the day, a rather counter-intuitive result as one would think exercise would make one hungry to make up for the calories lost.
I didn’t understand it at the time, but I had independently discovered ketosis. Once you run out of glucose in your blood and glycogen in your muscles, your body switches to turning fat into ketones. As long as you have enough fat (not a problem for most people), you can continually produce ketones for long periods of time without any food. Even the small amount of glucose your body needs can also be produced by the body without any need of dietary intake of carbohydrates. For a fat person, they literally can go months without food, as the body doesn’t only store energy in body fat but also nutrients. Cole Robinson of Snake Diet fame is an advocate of this method of fat loss — as he puts it, If you want to lose weight, fatty, stop stuffing food in your mouth. While in this state, you can remain active. The Piraha, according to Daniel Everett, would regularly go without eating on some days for no particular reason and at times would dance for several days without stopping for a meal. Cole Robinson talks about continuing his heavy weight lifting routine many days into fasting, not that most modern people with inferior health would want to try this. Under Genghis Khan, Mongol warriors began their war campaigns with an extended period of fasting, maybe to prime their body for ketosis that they maintained with their low-carb and animal-based diet (mostly meat, blood, and milk).
This relates to our evolutionary needs. Early humans survived as a hunting pack. We aren’t the fastest animal, among either predators or prey. We are rather slow actually and our lack of claws and fangs are a disadvantage, but we are endurance runners with the capacity to develop immense tracking skills. Along with ketosis that puts our large brains into overdrive, particularly the use of the pseudo-ketone beta-hydroxybutyrate, we have a special knack for sweating that keeps us cool, partly because of our lack of fur. Also, because of our upright position, our lungs aren’t constricted by our running gait and so our breathing is free to follow it’s own rhythm. Humans did all this while being barefoot for most of our existence, often running across rough ground. In particularly harsh environments such as Australia, the natives would develop thick callouses on the soles of their feet. We run better and more safely without shoes than with them — barefoot running (or using thin footwear such as sandals or moccasins) forces us to use good running form with impact shifted toward the toes rather than the heels. As natives observed, most animals move with the weight put on their toes. This is also what we humans are designed for.
Running is what humans do. Hunter-gatherers can track animals for days without having to stop for food and water and, as long as there is a water supply, could go on for weeks without food. This is natural. This was once the norm. This is how the human species managed to travel across deserts and oceans, how our ancestors survived starvation and ice ages. For hundreds of millennia, humans maintained such high levels of physical strain typically without harm to their health and rarely with injury. Fasting and feasting. Extended activity and periods of rest. And we are able to retain our physical capacities well into old age. Hunter-gathers in their sixties have the same level of running ability as they had in their late teens, with the developmental peak hitting around the late twenties. Many individuals in traditional societies go on running as their normal mode of travel until the day they die and, excluding early deaths from infection (infections, I might add, that mostly were introduced through colonialism), traditional people live as long as do modern Westerners. As said by Geronimo, a man who lived and fought under fierce conditions into older age, “My only friends are my legs. I only trust my legs.”
Even cold weather is not a big issue. An intriguing side of ketosis is that it has a built-in inefficiency. Burning fat produces excess heat, that is to say wasted energy. As Benjamin Bikman has speculated, this is likely because ketosis most often has occurred in the winter. The extra heat was a side benefit. So, fasting will not only give you immense energy from the superfuel of ketones but keep you warmer as well. Cold temperatures, like fasting, also promote autophagy which is healing. The body goes into its most optimal mode of functioning. Humans who are adapted to it can swim in freezing cold water for long periods of time or hike barefoot and half-naked in the snow as Wim Hof has demonstrated and, shown in research, all humans have such capacity for cold adaptation — it’s related to meditation techniques of warming the body where one sits in snow or on ice until it melts. Cold bathing and sleeping out in the open on cold nights, including with little clothing has been done by numerous populations: Australian Aborigines, Native Americans, etc. Make it a practice to take cold showers and you’ll get some small sense of the effect this can have — something I’ve been doing for a while and, to say the least, it is invigorating, but I’ve always been one of those crazy people who will go outside in the winter underdressed. By the way, Wim Hof at the other extreme has also run a half marathon through a desert without water. He has set many other world records, twenty-six in total.
Humans are adaptable, but a too easy and comfortable lifestyle has caused modern people to lose their adaptability. We aren’t meant to always be at the same temperature, always eating, always sedentary, or always anything else. Pushing the biological boundareies is a good thing to do on a regular basis. Consider hormesis — small amounts of stress actually increase our health. A similar thing is seen with exposure to bacteria and parasites when younger that can strengthen the immune system for life and alter how our bodies function. Even in seeking health, we moderns often get it wrong. We aren’t meant to continually do the same exercise in the same way over and over. Variety isn’t only the spice of life for it is also the meat of life. If we don’t use it, we lose it. This is why we should alternate how we exercise.
One method designed for this purpose is high-intensity interval training (HIIT) which is alternating between strenuous activity to exhaustion with periods of rest and repeating this multiple times. It forces the rhythm of your heart rate to expand its variability and that is good thing. Continuous exercise at the same pace, such as typical long distance running does the opposite in decreasing this variability. This is what can sometimes cause seemingly health long distance runners, once reaching the finish line, to drop dead from a heart attack. The lack of heart rate variability strains their heart too much in going from running to stopping. But this could be easily prevented by doing some HIIT exercise such as wind sprints, something I did a lot as a kid during soccer practice. Sometimes walk, sometimes jog, and sometimes run as fast as you can. That is what most of us did as children when playing and often we did it barefoot — I recall running on gravel alley barefoot, walking through the woods barefoot, and climbing trees barefoot. Why do we forget such natural behavior as we become mature, respectable adults? Don’t exercise. Just go play outside.
Our loss of connection to our species inheritance has cost us our health. But this loss isn’t an inevitable fate of modern civilization. We should take advantage of what we now know about human physiology. We humans are amazing creatures. There is a reason we have survived and thrived and spread all over the earth in nearly all environments and ecosystems. Even with all the unnatural strain and harm we put ourselves under, we still somehow manage to keep many of our physiological abilities. Imagine what we could accomplish if, rather than being sickly, our society operated with optimal health.
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Endurance running hypothesis
Endurance Running and Persistence Hunting
by David Carrier
Running After Antelope
from This American Life
Running After Antelope
by Scott Carrier
Why We Run: A Natural History
by Bernd Heinrich
Becoming the Iceman
by Wim Hof
The Way of the Iceman
by Wim Hof
What Doesn’t Kill Us
by Scott Carney
Science Explains How the Iceman Resists Extreme Cold
by Joshua Rapp Learn
Breathe Like The Iceman: How To Use The Wim Hof Method
by Harry J. Stead