This oft-quoted aphorism was originally penned by Friedrich Nietzche, the influential German philosopher, in ‘Twilight of the Idols’. It could also be used as a phrase to describe the notion of hormesis, a theory that comes up again and again in relation to creating a fitter and stronger body.
James Carney, an American journalist/writer, took Nietzche’s idea and in a book entitled What doesn’t kill us… demonstrated how it could be applied to a broad range of experiences. This followed on from a chance assignment to interview Wim Hof, a.k.a. ‘the Ice Man’. Hof is famous for embracing the cold, encouraging his followers to immerse themselves in ice filled baths or to climb snow covered mountains wearing only boots and shorts. He holds an impressive number of Guinness World Records, mostly involving progressively longer exposure to freezing temperatures. Although Carney originally approached the meeting with a degree of cynicism, he quickly realised that Hof was on to something very profound.
What is Hormesis?
Originally, the term ‘hormesis’ comes from the world of toxicology. The word itself was coined in 1943 by Chester Southam and John Erlich. The idea itself though, as a concept in toxicology, goes back to the 19th century. Hormesis denotes a positive response to a small dose of a toxin which, if the dose was much larger, would result in harmful consequences. Mild, repeated stresses, on a body can often result in stimulating the body’s ability to adapt to that stress; it becomes progressively more capable of dealing with it.
In the modern context, the word is often applied to situations wherein a human body can be exposed to a limited amount of a stressor, say cold for example, resulting in a greater adaption to that stressor. Exercise, cold showers or intermittent fasting all utilize this mechanism in a bid to enable the body to cope better with such demands.
Of course, the principal does not apply across the board. For example, a person does get used to smoking, but the resulting habituation is not something that any sensible person would wish for. The adaptation desired needs to be healthy and the stressor involved needs to be set at a sensible level. Cold exposure to the point of shivering is likely to elicit a healthy hormetic response, whereas cold exposure to the point of hypothermia is not.
The Danger of Comfort
The modern world which we inhabit is a place of great comfort, at least in comparison to previous times. We live in climate controlled environments, never letting ourselves feel too hot or too cold. We travel in vehicles rather than through our own efforts. We have access to more food than we can possibly eat. We love our ‘labour saving’ devices, heaven forbid that we should raise a sweat. We think in terms of convenience; the unquestioned assumption being that the easier something is the better.
At the superficial level, of course, this seems quite true. It is probably easier to live in the contemporary world than at any previous time in history. Unfortunately, this is not necessarily a good thing on either the physical or psychological level. Such comfort shrinks our capabilities as a person; it makes us weaker; we are limited by it.
If we never carry anything, we become incapable of carrying things. If we never run, we became incapable of running. If we always allow ourselves to be distracted by our electronic devices, we become incapable of focusing our attention, or even intention, for any extended amount of time.
Fortunately, the opposite is also true. Exposure to stress makes us more capable of dealing with that stress. If we carry our things we become adapted to carrying things. We get stronger. If we run on a regular basis we become adapted to running. Our bodies get fitter. If we force ourselves to focus on a task by spurning distractions, we become more focused. We are more able to concentrate.
Paradoxically, by embracing discomfort we increase the range in which we are comfortable within. If we routinely carry our bags at the airport, then having to carry bags when the need arises does not bother us. If we are used to running, then having to run for a bus or train on occasions is not a problem. If we are used to focusing on a task then having to do so unexpectedly is of no concern. In all these instances, because we are able to adapt to the demands, the range in which we feel comfortable increases.
What doesn’t kill us, makes us stronger.
Some Examples of Everyday Hormesis
The most obvious example of an everyday use of hormesis is exercise. We exercise because we know that our bodies will respond to the stress of exercise by becoming fitter. Immediately after the exercise session we will be weaker, and perhaps even for a few days later. If we repeat the stressing exercise, however, the body will get the message that it has to adapt to the new situation. The muscles will get stronger. This will increase your range of capability – you can then lift a heavier weight – your body has to adapt to the new demand by becoming stronger. And so on and so forth.
As I type these words, I am sitting in my kitchen at 7.30 a.m. having just come in from 15 minutes of cold exposure in my garden. This morning, according to my weather app, it was -4 degrees with a 20 mph wind. I still feel a little shivery, but my body is quickly adapting. Hopefully, if the physiological mechanisms are working as they should, brown adipose tissue is being formed on my shoulders and down my back. This will burn white adipose tissue (such as belly or hip fat) for fuel in order to adapt to the stressor in future. Through this process, the temperature range in which I feel at ease has increased.
Intermittent fasting, saunas and steam rooms, ischemic preconditioning and ingestion of small amounts of phytochemicals in our food are all examples of everyday hormesis. These examples, and many other minor stressors, can be used to extend the boundaries of what we are capable of.
Towards a Philosophy of Hormesis
Hormesis is such a useful mechanism to extend our comfort zone and capabilities, that we can even regard it as an attitude to be adopted. Further, we can even regard it as a philosophy to live by. Instead of merely allowing this to happen through serendipitous events, it could be argued that we would be better served by actively seeking out these challenges. To grow we need to forever challenge and extend our comfort zone.
If you never lift a weight it will be difficult to become stronger. If you never experience a little cold exposure you will feel forever uncomfortable if you have to deal with even a slight drop in temperature. If you never try a little fasting you will forever feel the need to snack at the slightest pangs of hunger.
If we limit our challenges, we limit our growth. On the other hand, if we allow ourselves to move out of our comfort zones, those zones are extended. A beneficent cycle is set up and we grow as people.
What doesn’t kill us, makes us stronger.