We live in a fast-paced world. Some of us may still remember a time when the pace was slower, when relaxation was just that - and not another thing on your to-do list.
Many of us, however, won’t recall such a time; this 24-hour global existence of work and social demands, planning, doing and relentless digital bombardments means that relaxing often involves unwinding with our face in a phone. But here’s the thing - because it is our “normal”, we may be so used to it that we don’t even realise that living this lifestyle is stressful, and stress is as much a part of our daily lives as eating and sleeping.
So, what happens in our body when it encounters stress?
You may have heard the story about the sabre-tooth tiger and our body’s fight-or-flight response, which kicks in when the body perceives danger – its purpose? To keep us safe.
The fight-or-flight response is a well-orchestrated survival mechanism controlled by the autonomic nervous system, the sympathetic arm, to be precise. Its partner in crime is the hypothalamic-pituatory-adrenal axis. They set in motion a chain of physiological events triggered by a cascade of hormones, which provide the body with a burst of energy to respond quickly and escape from perceived dangers.
The main players in this game are cortisol, adrenaline and noradrenaline. When the brain perceives stress, it signals their release and their actions result in a variety of physiological changes impacting the endocrine, cardiovascular, respiratory, gastrointestinal, musculoskeletal, immune and reproductive systems.
These changes are safe and designed to avert you from danger in the short term – remember the tiger. However, they should be transient; the release of the stress hormones should be self-limiting and stop when the threat has passed.
The thing is, these days, there is no tiger. Metaphorically speaking, our tiger is the work deadline, transport delays, harrowing news stories, and money worries…there tends to be no cut-off, stress becomes chronic (even though we may not realise it), and the impact on health begins.
Stress isn’t just an emotion
Did you know that you don’t have to feel psychologically stressed for your body to be stressed? Stress isn’t just an emotional experience. It is also a physiological one.
From the body’s perspective, stress comes in various forms but the underlying mechanism that drives the stress response is inflammation.
Inflammation is multifaceted and has numerous triggers:
- Allergens
- Insulin resistance
- Toxins (from within the body and outside)
- Nutrient deficiencies
- Malabsorption
- Physical trauma
- Psychological stress
- Hormone imbalances
- Obesity
And here’s the key thing – inflammation triggers the release of cortisol and if the source of inflammation isn’t resolved then cortisol levels remain elevated long-term.
Whatever the source, chronic stress has a far-reaching physiological impact, impacting digestion, immunity, and metabolism, to name but a few.
Left unchecked, it is implicated in many of the chronic health conditions that exist today, from mental health conditions such as depression and anxiety to fibromyalgia, type 2 diabetes, cardiovascular disease and IBS.
So how does stress show up in the body?
The Thyroid
The thyroid gland is a small butterfly-shaped gland in your neck that produces thyroxine (T4) and triiodothyronine (T3) hormones that regulate metabolism, energy levels and body temperature. The body needs to convert T4 to T3, which is the active hormone, but elevated cortisol impairs this conversion, leading to symptoms associated with hypothyroid, including fatigue, brain fog, intolerance to cold and unexplained and stubborn weight gain.
The Gut
The gut is intrinsically linked to the brain via the gut-brain axis and is very sensitive to stress. In fight-or-flight, the body slows down the digestive system and diverts energy to the more pressing matters at hand—remember the tiger? Well, chronic stress can cause digestive dysfunction from the top down. Stomach acid, digestive enzymes, and motility all take a hit, meaning everything can speed up or slow down, causing symptoms such as bloating, gas, constipation, diarrhoea, and reflux.
This can all impact the gut microbiome, which then exacerbates digestive issues, impacts mood, and increases inflammation throughout the body.
Metabolic health (the blood sugar part!)
During a stress response, the liver releases glucose (sugar) into the bloodstream for an immediate energy boost, designed to get out of danger. The trouble is that these days, we are usually sitting down facing off our attacker over the work laptop and not using that sugar hit to run away.
The problem is that over time, this can lead to prolonged elevations in blood sugar. If you have been following us for long enough, you will know that this is the root cause of insulin resistance (if not, you can read about that here). When you’re insulin resistant, your cells are not responding to insulin effectively, leading to even higher blood sugar levels. Left unchecked, this can lead to type 2 diabetes.
In addition, poorly controlled blood sugars can lead to sugar cravings, which is why we can find ourselves seeking out sweeter treats when we are stressed. Stress can lead to weight gain by driving behaviours such as emotional eating. Cortisol also impacts how the body manages fat – think cholesterol and how it stores fat—predominantly around the middle. Excess weight is itself a source of stress for the body, and so the vicious cycle continues.
The fight or flight system naturally increases the heart rate and blood pressure to flood the body with more oxygen and get the blood to the muscles to flee. The body does this by constricting the blood vessels. Imagine that constriction long-term. Hypertension is characterised by chronic vasoconstriction; it is a risk factor for developing type 2 diabetes and left unchecked, can lead to an increased risk of stroke, artery damage and heart disease.
Sex hormones
The reproductive system for both men and women involves a delicate balance of hormones, which are incredibly sensitive to the impact of stress. In men, chronic stress can lead to reduced testosterone production, erectile dysfunction and decreased sperm quality. Women may experience impaired ovarian function, leading to menstrual irregularities and infertility.
Stress and the immune system
Have you ever noticed how when you are stressed, you seem to feel constantly run down and get every bug going? Chronic stress can weaken your immune system, leaving you susceptible to viral infections. This dysregulation in the immune response may also be implicated in the onset of other conditions, such as an autoimmune disease.
How can we buffer this very modern phenomenon?
The good news is that by prioritising time for self-care and engaging in activities that support the parasympathetic nervous system, we can balance our body’s stress response and even increase our physiological resilience to it.
This is the other arm of the autonomic nervous system, and its role is to rest and digest—in other words, the very opposite of the fight-and-flight response. It helps our body to relax, repair and recover.
Meditation, deep breathing, gentle exercise, time in nature, gargling, singing, and chanting are all simple ways to support your body’s response to stress – but consistency is key. It should be a non-negotiable in your diary, just like your 2 pm meeting.
One final note is that stress can also impact our health behaviours. So if you find yourself doom scrolling, shallow breathing, tensing muscles, and reaching for sugary snacks, wine, or beer, chances are stress is at play, and now you know some simple tips to keep it in check.
