Hormesis: The Type of Stress You Need in Your Life

How cold was your shower this morning? Did you already spend some quality time in an ice barrel today? Any biohacker, longevity expert, or general high performer worth their salt knows the best way to start the day is to freeze your a** off, on purpose.

The cold plunge phenomenon has taken the internet by storm and has already achieved meme status. What was initially seen as weird self-inflicted torture done by nut jobs (like this author, who was *ahem*, utilizing cold exposure five years ago), has now become the go-to test of mettle for every Youtube entrepreneur scrambling for content.

The Ice Bucket Challenge called from 2014, they want their shtick back.

Multiple jokes aside, many individuals engaging in various forms of cold exposure may not understand the biological basis behind the practice, and why it can be beneficial. The principle they may be unwittingly taking advantage of is called hormesis, and a cold plunge is just one form of what's known as a hormetic stressor.

Hormesis is defined as a two-phased, dose-response relationship to an environmental agent, whereby low dose amounts have a beneficial effect, and high dose amounts are inhibitory to function or toxic.

Did you get all that? Basically it means the old saying "what doesn't kill you, makes you stronger" actually has some scientific merit. Hormetic stressors are controlled, acute stressors that trigger healthy adaptive responses. The critical descriptor is "acute", as prolonged or chronic exposure to many stressors has been proven to be detrimental to our health in a number of ways.

Hot/cold therapy, breathwork, intense exercise, and fasting are all types of commonly utilized hormetic stressors. In addition, naturally occurring compounds in certain plant foods (such as the glucosinolates in cruciferous veggies like broccoli) can have a hormetic effect. Plants that are exposed to more extreme conditions have adapted these compounds to make them more resilient, and consuming them can actually make us more resilient ourselves.

Talk about “You are what you eat!”  So how then, does hormesis work from a biological standpoint?

When utilized appropriately, a hormetic stressor disrupts the body's homeostasis just enough to activate cellular mechanisms that increase resilience, repair cellular damage, combat oxidative stress, decrease inflammation, and more.

Let's say we've just completed a challenging 45-minute HIIT style workout. This type of exercise will actually generate free radicals, the same cellular bad guys responsible for the oxidative stress that may lead to chronic disease over time. However, the presence of some free radicals isn't necessarily a bad thing, as it stimulates mitochondrial replication. Mitochondria are the organelles responsible for producing the energy our cells need to function, and losing them is one of the key hallmarks of aging.

By strategically placing our bodies under stress for short, controlled periods of time we increase our total population of mitochondria. This is good!

In addition, hormetic stressors may trigger the production of powerful antioxidant enzymes like glutathione which increases the body's capacity to neutralize toxins and oxidative stress. So the next time you're stepping into that sauna, know that the "detoxification" you're experiencing isn't just sweating out the corn dogs you've been scarfing. You may actually be increasing your total number of mitochondria and antioxidant capacity, therefore enhancing your resilience against future corn dogs (or something like that). 

It's key to recognize that hormetic stressors like saunas, cold water exposure, and intense exercise put our body on the defensive for a brief period. They're meant to be used periodically and strategically, not constantly.

In addition, the principle of hormesis is best employed as a preventative strategy, not something that will suddenly make you more resilient to stress you're already experiencing. Shocking your body with a cold plunge is probably not a good idea when it's already on high alert from crushing work stress, grueling workouts, and that 48 hour fast your gym buddy convinced you to do. By definition, hormetic stressors become damaging if utilized too much or too often.

That said, a 2020 research review from the Aging, Metabolism, and Emotion Center at UC San Francisco suggests that not getting enough of these hormetic stressors will prevent us from reaching optimal health and wellbeing. If we are too comfortable all the time, we become less resilient to the stressors we'll inevitably encounter throughout life.

So get comfortable sitting in physical discomfort, at least in short bursts. Take it from social media, if you cold plunge at 5am just right, you might just become a millionaire in the process.