Understanding stress: what stress does to your body, and when it matters
- J. Shillabeer & C. Rodgers
- 15 hours ago
- 11 min read
Stress shows up in the body long before we name it as stress. Nutritional therapists Chandy Rodgers and Josie Shillabeer on what is actually happening, and when to ask for help.
Most of us only register that we are stressed when it becomes obvious: a deadline, a diagnosis, a difficult few months. But the effects of stress begin much sooner, and it happens whether or not you have registered feeling stressed. Your heart rate, your digestion, your sleep, your appetite, and your ability to concentrate are all part of the same response.
The effects of stress on your body are not always something you need to be concerned about. However, stress can be a key driver in many unwanted imbalances within the body that can have both physical and psychological consequences. By the end of this article, you will have a clearer understanding of what stress is, what it does, and what you can do about it.
In this article, we'll explore:
What is stress?
Stress is the body’s natural response to any demand or disturbance, which triggers the ‘stress response’. This disturbance or demand can be positive (e.g. a new job or community group) or negative (e.g. job loss or illness).
A certain amount of stress is an unavoidable, normal part of life. It can provide motivation and interest, leading to a more exciting and fulfilling life, and it is also the system that protects you from real dangers.
However, if the stress response is activated to an extreme level (acute stress), or continues for a long time (chronic stress), it can negatively affect your health and wellbeing.
Is it stress or anxiety?
These two words are used interchangeably, and the difference is genuinely useful to understand.
The main difference is what causes them and how long they last:
Stress is typically a response to a specific challenge or pressure, such as exams, work deadlines, or relationship problems. It often improves once the stressful situation is resolved.
Anxiety is more about anticipation: worry about what might happen, which can persist long after any obvious trigger has gone, and sometimes without one at all.
Both are normal human reactions, and feeling anxious from time to time does not mean there is anything wrong. If you feel anxious a lot, for months at a time, or the feelings are strong, distressing, or hard to control it, this is when they should be taken seriously.
What happens during the stress response?
Imagine you are walking through a woodland and suddenly come face to face with a bear.
When your brain perceives a threat, it doesn’t wait for permission to act. Your nervous system reacts instantly, before you’ve had a chance to consciously think it through.
Hormonal response
The hormone adrenaline arrives within seconds of a perceived threat and produces most of what you notice: the pounding heart, the shaking hands. Then the hormone cortisol follows more slowly, released through a chain of signals between the brain and the adrenal glands, and its job is to keep energy available while the demand continues.
Physical response
Your heart races, pumping blood faster to deliver oxygen and fuel to your muscles, so you’re ready to fight or flee.
Your blood pressure rises, pushing blood quickly to where your body needs it most: your major muscles and vital organs.
Your breathing quickens, drawing in extra oxygen to fuel fast movement.
Your muscles tense, priming your body to react quickly, whether that’s to run, defend yourself, or brace for impact.
Your hands and feet cool down as blood vessels near the skin’s surface constrict, redirecting blood away from your extremities and toward your core, muscles, and vital organs.
You start to sweat, helping regulate your body temperature so you don’t overheat while your body is working harder.
Your mouth goes dry, since digestion isn’t a priority in a crisis, so saliva production and gut activity slow down.
Your stomach knots up as blood flow is diverted away from your digestive system, which can cause that familiar tight, uneasy feeling.
Your liver releases stored sugar, flooding your bloodstream with glucose for a quick hit of usable energy.
Stress hormones flood your system as adrenaline and cortisol surge, priming your body for one of three responses: fight, flight, or freeze.
Fight, flight, or freeze
Primed and ready to take on the perceived threat, your body and mind can respond in three different ways.
Fight: is when your instant reaction is to face the stressor head-on. For example, there is smoke coming out of your toaster and you quickly switch it off at the wall. Or, with a bear, you make yourself as big as possible and get ready to take it on.
Flight: your instinct is to get out of the situation as fast as possible. Smoke is coming out of the toaster and you run to find someone else to deal with it. Or, with the bear, you run and try to find somewhere to hide.
Freeze: This one is frequently missed when talking about stress, but for many people, they can freeze, even just for a second. The perceived stressor is so overwhelming that you do not respond at all and feel frozen. For example, the toast continues to burn, unsure of what to do, or you simply stare at the bear and try to be small and quiet.
Most people will experience all three at different times, and for different lengths of time, depending on the threat they are facing.
Why do you have a stress response?
Your body has a remarkable inbuilt survival system that has evolved over thousands of years. It is primed to protect the human body against predators, enemy tribes, famine, extreme weather, etc. This ‘stress response’ is the reason your ancestors survived, and the reason you are here today.
Modern life differs greatly from that of our ancestors; we have brick homes, central heating, and supermarkets. You would therefore think this protective system would rarely be needed, and in truth it isn’t. But while you know that a forgotten birthday present is not life-threatening, your protective system cannot tell the difference.
When you come across a physical or emotional challenge, this survival system kicks in before your rational mind can catch up. This results in varying levels of symptoms, based on the level of danger perceived and how long it takes for you to rationalise the situation.
Unfortunatly evolution does not happen overnight and our systems are unlikely to adapt to modern life for many generations to come. Therefore up to us to keep this system under control, reducing stressors and understanding what we need to do to rebalance the body.
What stress does to your body: the good and the bad
This is the part that most stress advice skips, and it changes how the whole subject feels.
In the 1930s the endocrinologist Hans Selye described stress as unfolding in three stages: an alarm phase, where the body mobilises; a resistance phase, where it adapts and returns towards balance; and, if the pressure continues for long enough without relief, an exhaustion phase. The first two stages are not the problem. They are the system working exactly as it should. It is the third that costs.
When stress works for you
Exercise is the clearest example. A hard training session is a genuine physical stressor. Your heart rate climbs, stress hormones rise, and the body is temporarily pushed out of balance.
The reason this is not a problem is that the recovery afterwards leaves you slightly better off than you were before. Your muscles, bones, lymphatic system, and cardiovascular system all adapt and strengthen. Researchers describe this pattern as hormesis: a small dose of a stressor prompting an adaptation that a large or unrelenting dose would not.
The same logic applies to a job interview. You enter a period of acute stress, followed by relief and recovery. Used occasionally, for the things that matter to you, this kind of stress is genuinely useful.
Even the immune system appears to follow this pattern, with short-term stress seeming to enhance immune responses while long-term stress appears to dysregulate them.
When stress stops working for you
The problem arises when stressors, real or perceived, are extreme or continuous. The same responses that are useful for minutes become costly over months.
Excessive exercise without rest, months of job interviews and money worries with no end in sight, and an immune system that never gets to stand down can all take a real toll.
Stress is therefore not automatically bad. It just needs to be kept in proportion to recovery.
How does stress show up in your body?
When we experience the continuous and varied stressors of modern life, it can have a noticeable effect. Among the things people commonly notice::
Bloating, indigestion, or changes in your bowel habits because digestion works less efficiently when your body is focused on dealing with stress
Headaches, jaw clenching, or tight shoulders from holding tension without realising it
Brain fog and poor concentration because your mind is constantly switching between demands
Waking during the night because your nervous system finds it difficult to settle completely
Feeling “wired but tired”, where you’re exhausted but can’t properly relax
Becoming more emotional, impatient, or tearful over things that wouldn’t normally bother you
Sugar cravings or constantly reaching for caffeine because your brain is looking for quick energy
Catching every cold that’s going around because chronic stress can influence immune function over time
Two things are worth saying about that list.
The first is that none of these symptoms automatically means stress is the cause. They can have many explanations, several of which need investigating properly, so it is always worth seeking medical advice if they are persistent, severe, or new. But they can also be your body’s way of warning you, “I’ve been carrying too much for too long.”
Why does stress affect digestion, sleep, and energy?
As nutritional therapists, these are the three that come up with clients most regularly when we are discussing stress.
Digestion: The vagus nerve is a powerful highway that runs between the gut and the brain and the brain and the gut. The vagus nerve is highly sensitive to stressors in both directions, and this is why it is typically one of the first systems within the body that people notice symptoms. During the stress response, blood flow is directed away from the digestive system, and gut activity slows. That is why nerves produce butterflies, and why eating in a hurry, while working, or mid-argument tends to sit badly.
Sleep: is often the first thing to go and the last to come back. Cortisol follows a daily rhythm that should be high in the morning and low at night, and repeated stress disturbs that delicate pattern. This results in feeling tired all day and then wired but tired when you are trying to fall asleep.
Energy: this is where the two meet. Broken sleep, blood sugar imbalances, and an under-functioning digestive system can all lead to a reduction in energy.
Understanding what is triggering your stress response, and finding ways to reduce it, is key to rebalancing all three. While these may be obvious and easy to change for some, they can also be very complex and intertwined for others, and this is when it is a good idea to seek professional support.
Why do some people cope with stress better than others?
Two people can face the same week and finish it in completely different states. Some of that is circumstance, some is temperament, and some is simply what else was already going on.
But a great deal of it comes down to capacity: how much you were carrying before this week started, and how much opportunity you have had to recover.
It also explains something most of us have experienced. On a good day, a cancelled train is an inconvenience. On a bad one, it is the thing that finishes you. The train has not changed. Your capacity has.
The most useful way to think about this is the stress bucket, a model that treats your capacity as a container that fills with everything you are carrying, including the many small things you never counted. We have covered it in full, along with the practical ways to build capacity and release pressure, in our guide to the stress bucket.
What can you do about stress?
As we have learnt stress is a normal and important part of our makeup. The aim is not to eliminate all stressors from our lives; instead; it is to ensure that it is in balance with recovery from these demands. Here are some ways to help keep these in balance:
Reduce any demand that is within your control
Say no to the invitation that lands on your one day off
Sit down once a week and make a meal plan, rather than panicking every day about what to eat
Look for professional support with symptoms that are placing extra demands on your body
Support your body so it copes better with what remains
Dedicate time each week to rest and relaxation
Protect your sleep, and follow good sleep hygiene
Find more ways to move throughout the day:
Exercise
Housework
Standing desks
Spend time with people you trust and can make you feel held/supported.
Eat a more balanced diet with specific focus on:
Balancing your blood sugar levels
Increasing protein rich meals
Reducing your reliance on caffeine, sugar and alcohol
You can learn more about how to balance your blood sugar levels and eat a more balanced diet by enrolling in one of our self-guided online courses, hosted by nutritional therapist Josie Shillabeer.
When should you speak to someone about stress?
There is no threshold you have to reach first. Noticing that you are struggling to cope is enough.
Where to find someone to speak to about stress?
Primary care
The NHS advice is to see a GP if you are struggling to cope or if the things you are trying yourself are not helping. If you need help urgently but it is not an emergency, you can call NHS 111. If you or someone you know needs immediate help, or you have seriously harmed yourself, call 999 or go to A&E.
Complementary care
As qualified nutritional therapists, we advise that you seek the support of your primary healthcare provider (i.e. your GP) first. Several common and very treatable conditions produce almost exactly the same picture.
Once these have been ruled out, we highly recommend that you seek the support of a complementary healthcare professional, such as a nutritional therapist or talking therapist, for further support alongside your GP.
Qualified nutritional therapists typically have more time to look at the full picture: the symptoms your body is communicating, and all the demands on you, both now and in the past. By piecing everything together, nutritional therapists can build a personalised plan and work on the things likely to make the biggest difference first, so you are not left making every decision on your own. Our practitioner directory is a good place to find a qualified practitioner near you.
Friends and family
While it is important to seek qualified support, don’t forget the people already around you. Feeling stressed is far more common than most people realise, and it can seem as though everyone else is thriving while you are quietly drowning. Talk to colleagues, friends, and family, and start a conversation. Many will share what helped them, and it can be reassuring to see that there is a way through.
Final thoughts
Stress is not the enemy. It is a normal, necessary response, and in short bursts it is genuinely useful: it sharpens your focus, carries you through the interview, and gets you home safely. The problem was never stress itself. It is that a system built for occasional, short-lived demands is now being asked to run almost continuously, with very little chance to stand down in between.
That is why the aim is balance rather than elimination. Not a life without pressure, but one where the pressure and the recovery are somewhere near proportionate. And that balance is rarely restored by a single dramatic change. Its rebalanced through ordinary things: eating regularly, protecting your sleep, moving your body, spending time with people who make you feel safe, and being willing to put something down or say no.
If there is one thing worth taking from this article, it is that noticing early is far easier than recovering late. You do not need to be at breaking point to take your stress seriously. Asking sooner simply makes it easier to put right.
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