Why are some things ‘good for us’? Why does aerobic exercise improve cardiovascular health? Why does lifting weights over a prolonged period of time increase muscular strength and muscular endurance? Why does skipping the occasional meal increase insulin sensitivity (your body’s response to insulin)? What is it they do which is beneficial and how does it work? Hormesis is the answer.

The response which allows for these beneficial adaptations to occur is hormesis. You may have heard Kelly Clarkson’s song, “(Stronger) What doesn’t kill you” (makes you stronger).

Well, that’s actually true to some extent (depending on the dose). By dose, I’m referring to toxins or stressors. All organisms like to maintain homeostasis which is balance within the body. When stressors such as lifting weights, exercise or even drinking more alcohol than your body would like to handle are imposed upon the body then the body is forced to try to adapt. Hormesis is about the body adapting to maintain balance or homeostasis within a changing environment.

If you run 4 x mile repeats at a pace and intensity which your body struggles with, afterwards, your body will do its best to adapt so it can handle the same situation better next time. Your body super-compensates for the stressor by making you able to handle it better the next time the stressor is encountered i.e. the next time you run 4 x mile repeats. This is one of the ways your body tries to protect you. Essentially hormesis is a broad way of looking at the adaptation process which occurs within you.

What Is Hormesis?

Hormesis is any process in a cell or organism that exhibits a biphasic response to exposure to increasing amounts of a substance or condition.

By biphasic response, this means that the response can either stimulate an adaptation or cause an inhibitory response. The adaptation can be stimulated by lower doses of the substance or condition, whereas too much of it can cause an inhibitory response which may result in a weakened immune system or perhaps an overuse injury from, say, running too much too early without allowing your bones to get stronger to withstand the impact of running.

The condition which causes this biphasic response is usually stress. Stress helps you adapt, but too much of it isn’t good and leads to chronic stress which comes with a lot of potential health risks. Hormesis can improve your health by allowing you to adapt to stressors in small, controlled doses.

Further reading: 11 Ways To Reduce Chronic Stress

This graph below should make it easier to visualise.

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Hormesis dose response, with dose usually being a stressor or toxin

Hormesis – Stress Helping You Adapt

If you think about all your significant achievements in your life, how many of them were easy?

I expect the answer is ‘none’ or very few if any, otherwise they wouldn’t be significant.

A German philosopher, Nietzsche said, “That which does not kill us makes us stronger.” To that, I think a few examples can be used.

  • To get stronger, you have to lift progressively heavier weights.
  • To get faster, you have to run as fast as you can.
  • To become more alcohol-resistant, you need to slowly increase the dose of alcohol consumed.
  • To get smarter, you need to challenge yourself mentally.
  • To eat more healthily, you need to change your eating habits.

None of these examples are necessarily easy to do, and I wouldn’t recommend drinking lots of alcohol just so you can drink more without becoming intoxicated. The point is, by challenging yourself in these ways you are helping your body to produce a hormetic response. However, as depicted in the diagram above, we need to be careful that the dose isn’t too large otherwise an inhibitory response is more likely to occur which will not help stimulate an adaptation.

Whilst chronic stress can significantly undermine and cause your health to deteriorate, acute bouts of stressors can vastly improve health, immune function and the body’s ability to adapt to stress.

How Hormesis Can Improve Your Health

So we know now what hormesis is – your body’s cellular response to a stressor. And we know it helps the body to adapt, but how else can it improve your health? Here are some of the hormetic stressors which can cause beneficial adaptations in the right doses.

#1 – Cold Water Plunges

Brrrr. Yes, I know this is probably one stressor you want to avoid – but that’s exactly what makes it beneficial! The fact that it’s an acute stressor is why it helps to elicit an adaptive response. In one study on swimmers, ice bathing was shown to increase oxidative stress markers, but the markers for endogenous antioxidant production were increased. In addition, cold exposure improves anti-tumour immunity through the hormetic response.

Cold exposure is also known to trigger AMPK, an enzyme and fuel sensor which causes your mitochondria (cell organelles) and improve their efficiency in respiration, the process of releasing energy. As well as this, cold exposure can help reduce inflammation, improve the immune system and increase pain tolerance.

Here are a couple of ways to attempt to elicit this hormetic response:

  • Sit in a bath using only cold water for 5 – 20 minutes (submerge your upper body if you dare).
  • At the end of your shower, turn the temperature as cold as you can bear for 30 seconds.

#2 – Caloric Restriction / Intermittent Fasting

Reducing energy intake or going for prolonged periods of time without food is an easy way of reaping the benefits of hormesis. Both have been linked to increased longevity.

Intermittent fasting simply involves reducing the eating window where you’re in a ‘fed’ state during the day whilst caloric restriction involves reducing calorie intake (obviously).

The main hormetic mechanisms linked to increased longevity are thought to be:

  • Reductions in growth factor IGF-1 (low levels are linked to increased longevity)
  • Increased cellular autophagy (the process of recycling dead and weak cells and producing new, stronger ones)
  • Reduced levels of inflammation
  • Cancer prevention properties
  • NRF2 activation (a transcription factor which expresses certain genes involved in cellular protection, antioxidant status and DNA repair)
  • Inhibition of mTOR (a major pathway for cellular growth and reproduction)

When you are in a ‘fasted’ state, these hormetic mechanisms are triggered and switched on. When in a ‘fed’ state, they are switched off so these benefits are not accessible.

#3 – Exercise

The hormetic response to exercise depends on several factors:

  • Intensity (of max heart rate)
  • Duration (how long at what intensity)
  • Frequency (how often you train)
  • Type (the form of training you partake in)

The accumulation of these factors determines the amount of oxidative stress and muscular damage your body undergoes. Inflammatory markers are elevated after exercise and if you do it at a high intensity, there’s a high likelihood cortisol (the stress hormone) is elevated as well.

Whilst you may feel pain after exercise, be tired and hungry, this is all part of the recovery process. Giving yourself adequate rest, high-quality sleep and fuel your body with the right nutrition to speed the recovery process, so your body is fitter and stronger for the next bout of intense exercise you take on.

After exercise the following cellular activities occur:

  • Increased mitochondrial density
  • DNA repair is enhanced
  • Heat shock proteins are activated (which protect against molecular damage)
  • Your central nervous system adapts and expects the next workout to be at least as challenging as the workout just done
  • Enhanced brain function due to the extra blood flow around the body (more oxygen goes to the brain)
  • Anti-inflammatory compounds are released into the blood during the growth and repair process

These processes help your body to adapt to physical stress induced by exercise so that the next time you have to undergo a workout of similar intensity, your body should be able to handle it better and perform better.

#4 – Plant Phytochemicals

One of the reasons we’re told to eat lots of fruit and vegetables, particularly of a range of colours is so that we consume the phytochemical compounds within plants. We’re told that these plants contain antioxidants which help to fight off free radical oxygen species and oxidative damage to our cells.

Interestingly, more evidence is amounting to suggest that these bioactive phytochemicals such as polyphenols and phenolic acid, exert their health benefits by hormesis. They work by irritating our body enough so that our body responds causing our cells to super-compensate at an adaptive cellular level. This results in many of the health benefits which vegetables and fruits are known for.

#5 – Sunlight

Quite a lot of people I know enjoy being in the Sun. Who doesn’t like it? It feels good.

In fact, tanning helps protect skin from sun damage, reduces skin cancer and is an indicator that our bodies are producing more vitamin D – win-win!

However, like any other hormetic response, too much is bad. Too much and your skin cells die, you get sunburn (ouch!) and there’s an increased risk of skin cancer.

#6 – Heat Exposure

Heat exposure helps to active heat-shock proteins which help cells to resist the damaging properties of heat. As well as this, high temperatures also help to stimulate the lymphatic system, which works like a pump for moving liquids and toxins within the body.

#7 – Mental Stress

A form of hormesis is when you’re forced to use your neural muscles within your brain. This includes gaining more knowledge, learning new skills, experiencing unpredictable high-stress situations and being in new environments. These situations trigger neurogenesis (the process of producing new neurons) which creates new brain cells and helps the formation of synaptic connections within the brain. This actually helps to improve your brain’s resilience to future stressors so you can deal with them better mentally.


Did you know about hormesis? Do you plan on incorporating it into your daily life? If you found this article useful please share it!