STRESS, CORTISOL AND HEALTH

By Dr Bayne French

Brian asked me to write about stress. At first, I assumed he meant my own stress, and I warned him it could easily turn into a 20,000-word horror story — especially if I included the incident involving a grizzly bear. Thankfully, he clarified that he wanted an article about the effects of chronic stress and elevated cortisol levels on health, and more importantly, what can be done to improve them.

Cortisol and the HPA Axis

Hormones are chemical messengers produced in one part of the body that travel through the bloodstream to affect other organs and tissues. They regulate nearly every biological process, including growth, metabolism, immune function, inflammation, sleep, mood, bone density, and even gene expression.

One of the body’s most important hormonal systems is the HPA axis, which stands for the Hypothalamus-Pituitary-Adrenal axis. This system connects the brain to the adrenal glands.

The process works as follows:

1.   The hypothalamus in the brain releases a hormone called CRH.

2.   CRH signals the pituitary gland to release ACTH.

3.   ACTH then stimulates the adrenal glands to produce cortisol.

In simple terms, long-term stress and poor lifestyle habits can lead to excessive cortisol production, beginning in the brain itself.

Cortisol is a steroid hormone made from cholesterol and produced by the adrenal glands, which sit above the kidneys. These glands also produce adrenaline and other important hormones. Because of their widespread influence on health, many practitioners in functional medicine believe that improving adrenal function is a key starting point when addressing health issues.

The Natural Cortisol Rhythm

Cortisol naturally follows a daily rhythm. Levels are highest in the morning to help wake us up and provide energy for the day ahead. This is known as the Cortisol Awakening Response.

Levels should then gradually decline throughout the day and be at their lowest at night.

Short-term stress — such as poor sleep or traffic — can temporarily raise cortisol levels. However, chronic stress from illness, work pressures, relationship difficulties, financial strain, or poor diet can keep cortisol elevated for long periods.

Persistently high cortisol levels can negatively affect:

• Sleep quality
• Mood and mental health
• Blood pressure
• Blood sugar control
• Weight gain and cravings
• Bone density
• Inflammation

Modern life exposes many people to ongoing stress without adequate recovery, and this is increasingly linked to long-term health problems.

Cortisol Testing

Conventional medicine usually only tests cortisol when doctors suspect severe conditions such as Cushing’s Disease or Addison’s Disease, both of which are relatively rare.

However, more subtle disruptions in cortisol patterns are far more common.

Anything that places stress on the body may affect cortisol levels, including:

• Overtraining
• Injury
• Infection
• Poor diet
• Gut health issues
• Food intolerances
• Emotional stress
• Environmental toxins

A useful method of assessing cortisol is a four-point saliva test, where saliva samples are collected:

• Upon waking
• At midday
• Around 4pm
• Before bed

This helps identify whether cortisol follows a healthy daily pattern or remains abnormally elevated throughout the day.

One common unhealthy pattern is a “flat curve”, where cortisol remains consistently high instead of decreasing properly. Research has linked this pattern with an increased risk of cardiovascular disease and higher overall mortality.

Cortisol and Weight Gain

Stress affects appetite differently in different people. Around 70% of people eat more during stressful periods, while 30% eat less.

Studies show that people who release higher amounts of cortisol during stress are more likely to crave high-calorie comfort foods, particularly sugary foods.

Over time, this can lead to:

• Increased insulin levels
• Fat accumulation
• Obesity
• Poor cholesterol levels
• Abdominal fat gain

Excess cortisol particularly affects visceral fat — the fat stored around the abdominal organs. This type of fat is strongly associated with heart disease, diabetes, and other serious health conditions.

Research also shows that diets high in sugar are linked with higher cortisol levels and greater belly fat accumulation, especially in younger people.

Interestingly, studies found that:

• Protein and healthy fats did not increase cortisol in the same way
• Omega-3 intake appeared protective against visceral fat accumulation

Many endurance athletes struggle with abdominal fat despite high training volumes. A common issue is chronic stress combined with frequent consumption of sugary sports fuels, processed carbohydrates, and alcohol. Elevated cortisol combined with poor nutrition can override the benefits of exercise.

Improving Cortisol Balance

Several lifestyle interventions have been shown to help regulate cortisol and support a healthier HPA axis.

Diet

Sugar can temporarily reduce stress hormones, which partly explains why people crave comfort foods under stress. However, over time, excessive sugar intake contributes to higher overall cortisol levels and increased abdominal fat.

Breaking this cycle is important.

A lower glycaemic, lower carbohydrate diet that focuses on healthy fats, quality protein, and minimal processed sugar may help support healthier cortisol patterns.

Exercise

Regular movement improves resilience to stress and helps regulate hormone function.

This does not necessarily require intense training. Even regular walking has been shown to improve hormone balance, strength, and overall quality of life.

A balanced routine combining cardiovascular exercise with strength training appears most beneficial.

Meditation and Mindfulness

Studies have shown that meditation can reduce cortisol levels and improve stress-related biomarkers.

Mindfulness practices may help improve emotional resilience and reduce the physiological impact of stress.

Massage

Massage therapy has been shown to reduce cortisol levels while increasing serotonin and dopamine — neurotransmitters associated with improved mood and wellbeing.

Sleep

Poor sleep and elevated cortisol often create a vicious cycle:

• Poor sleep raises cortisol
• High cortisol further disrupts sleep

Long-term sleep problems significantly increase disease risk and should be properly addressed rather than ignored.

Gut Health

The gut microbiome plays a major role in regulating stress hormones.

Poor gut health can disrupt the HPA axis, while chronic stress can negatively affect gut bacteria.

Supporting gut health through:

• A nutritious diet
• Fermented foods
• Prebiotics
• Probiotics

may help improve stress resilience and hormone balance.

Dark Chocolate

Dark chocolate rich in flavonoids has been shown to reduce stress hormone levels.

While moderation is still important, flavonoid-rich dark chocolate may offer genuine health benefits.

Conclusion

Stress itself is not always harmful. In many situations, it can sharpen focus, improve resilience, and help people perform under pressure.

Perspective matters greatly. How we interpret stress can influence how our bodies respond to it.

Improving health requires consistent attention to:

• Stress management
• Quality sleep
• Regular movement
• Proper nutrition
• Mindfulness
• Recovery

Many of these factors are within our control. By improving them, we can support healthier cortisol levels, reduce disease risk, and improve long-term wellbeing.