My brother told me a few years ago that if he doesn’t run almost daily, he starts to feel antsy. After questioning whether we were actually related (I have to force myself to put down my glass of wine and pull on my running shoes), I asked him if he understood how diet and exercise help control stress and anxiety.
Most people have heard or read that exercise is an effective way to manage stress. Many also know, from personal experience, how much regular activity helps. But few understand why what we eat and how we exercise influences our stress levels.
Back when we lived in caves and spent our time hunting and gathering, stress was an essential survival response. If we encountered a sabre-toothed tiger, our bodies reacted in a way that helped us run away quickly. This is often called the fight or flight response.
When faced with danger, our bodies activate part of the nervous system known as the sympathetic system. Alongside the release of cortisol and adrenaline, this creates several physical changes. Heart rate and blood pressure increase to pump more blood to our muscles.
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Breathing speeds up, airways widen and pupils dilate so we can see danger more clearly. Blood flow is redirected away from the stomach and towards the muscles, while glucose is released into the bloodstream to provide energy. The physical activity that follows helps use up these stress hormones, allowing the body to return to normal.
Why modern stress keeps the body switched on
This response was useful when we were in real danger. Today, however, most stressful situations do not require us to run for our lives. As a result, the sympathetic system can remain activated.
Cortisol and adrenaline levels stay high, which keeps heart rate and blood pressure elevated, impairs digestion and weakens the immune system. High cortisol levels are also linked to low mood, reduced motivation and increased anxiety.
Cognitive function can be affected too, impacting memory and focus. With chronic stress, this state can become the norm, placing the body under constant strain. Over time, it can have serious consequences for health and wellbeing.
Exercise as a reset for the nervous system
Exercise is one of the most effective ways to reduce cortisol levels. It helps use up excess stress hormones and allows the body’s systems to return to normal. It also activates the parasympathetic system, often referred to as the rest and digest system.
Reducing stress through exercise is not just about running or cardio. Activities that activate the parasympathetic system, such as yoga, stretching, breathwork, cold-water swimming or even a walk with a friend, can help keep the nervous system balanced and stress hormones under control.
Stress also affects our eating habits. Raised cortisol increases the body’s need for energy, often leading to cravings for foods high in sugar and fat. Stress eating can also be emotional or habitual, with people eating without hunger as a form of self-soothing.
In addition, stress often disrupts sleep, leading to fatigue. To cope, people may turn to stimulants like caffeine or high-calorie snacks. It can lead to increased food intake, fat storage and weight gain.
The hormone cycle behind weight gain and cravings
High cortisol levels promote fat storage around the abdomen, known as central adiposity. This is linked to a higher risk of type 2 diabetes, heart disease and breast cancer. Abdominal fat also lowers levels of leptin, the hormone that signals fullness, while increasing ghrelin, which stimulates appetite. This creates a cycle that can lead to further weight gain.
Just as stress can lead to poor food choices, research into the gut-brain connection shows that the gut microbiome influences mood and mental health. Diet, stress and wellbeing are closely linked, and without intervention, this cycle can become difficult to break.
Blood sugar fluctuations caused by diets high in processed foods and refined sugars have been linked to increased anxiety, irritability and mood swings. These foods can also increase inflammation, which in turn raises cortisol levels.
From a dietary perspective, there are some simple steps you can take to help manage this cycle:
Eat omega-3
Foods rich in omega-3, such as oily fish and certain vegetables, can help reduce inflammation and support healthy cortisol levels.
Plan ahead
If you rely on convenience foods due to a busy lifestyle, try meal planning or batch cooking to create healthier options.
Measure and find what works for you
Be mindful of portion sizes and check nutrition labels. Identify healthier choices at your usual lunch spots and aim to stick to them. Simple swaps, such as pairing a salad with grilled chicken instead of choosing a pre-packaged pasta dish, can make a difference.
Make a list
Keep a list of healthier snack options to reach for instead of high-fat, high-sugar foods. Try combinations of protein and carbohydrates, such as apple and peanut butter, houmous and carrot sticks, cheese and celery or boiled eggs.
Treat yourself
When you feel the urge to eat, ask yourself whether you are truly hungry or responding to stress. If it’s the latter, consider other forms of reward, such as a warm bath, a favourite TV show or a small treat.
How you move and what you eat can have a real impact on your stress levels and overall health. Understanding the link between diet, exercise and stress can help you feel more in control and support long-term, positive change.
Claire Small
Claire Small is the Chief Clinical Officer and Co-founder of Pure Sports Medicine. As well as delivering expert Physiotherapy programmes from Pure Sports Medicine’s Kensington Clinic, Claire is also an Honorary Lecturer and Examiner at Queen Mary University of London, Invited Lecturer at UCL and Kings College in London and University of Bath, and a national and international lecturer on manual therapy, spinal, hip, and pelvic pain. Claire’s written career includes being a journal reviewer for Manual Therapy and Physical Therapy in Sport, and The British Journal of Sports Medicine.
