“This job is killing me”
There is growing evidence that stress is a major factor in the development of metabolic syndrome, primarily via obesity
In this blog, I want to cover the complex relationship between stress, obesity, and metabolic syndrome. We will look at our response to stress, including the release of stress hormones; why chronic stress can lead to obesity, while acute stress can result in your being underweight; why a low weight at birth is a risk factor for obesity in adulthood; and how to measure chronic stress.
Obesity is the most common metabolic disorder in clinical practice. With a range of other risk factors, including hypertension, high blood glucose, abnormal blood fat (high triglyceride), and low HDL (good) cholesterol, obesity constitutes the metabolic syndrome.
What is stress?
Imagine a tiger in the jungle is chasing you. Your body mobilises energy stores to respond to a life-threatening situation to ensure your survival. This makes Your heart beat faster and stronger, your blood pressure rise, you become sweaty, and your pupils dilate. These are signs of acute stress; however, symptoms of chronic stress include rapid and shallow breathing, anxiety, stomach pain, acid reflux, back, and neck muscle spasm.
Of course, not all stress is bad. Stress helped our ancestors to survive life-threatening events, such as the above encounter, and it can also help us today to meet our deadlines and achieve our goals.
Stress today can be caused by logical, psychological issues, such as grief, fear, anger, sadness, frustration, anxiety, and panic attacks. It can be the result of other psychosocial situations at work, or in marriage and family, in social isolation, loss of loved ones, loss of job, and lack of social support. It can be induced by purely internal physical means, such as dehydration, lack of essential nutrients, fluctuation in blood sugar, accumulation of body toxins—the latter result in the person feeling extremely stressed out without an obvious external stressor.
Acute and chronic stress
Acute stress helps the body adapt to acute situations such as trauma, infection, or surgery; chronic stress can result from dysfunctional family situations, a bad work environment or unhappy marriage. Chronic stress is more harmful, and if it continues or happens regularly, it may lead to adrenal fatigue or exhaustion.
Physically, this is how stress works. The stressor, if it exceeds a certain level, activates various pathways to stimulate the adrenal gland to release stress hormones (cortisol and adrenaline.) This stress response is focused on mobilising your body’s resources (including energy stores) for optimal performance to fight or flee the danger.
And depending on how you perceive the challenge, you may experience emotional consequences, referred to as distress, and these may result in anxiety or depression or a reduction in quality of life.
The stress response stimulates two different layers of the adrenal gland. Acute stress activates the inner part of the adrenal gland, known as the medulla, to produce mainly adrenaline; however, stimulation of the outer layer (cortex) takes place during chronic stress to produces cortisol.
These responses happen through two different pathways. Acute stress predominantly activates the sympathetic adrenal medullary (SAM) system to produce Catecholamines (adrenaline), whilst chronic stress activates the Hypothalamic Pituitary Adrenal (HPA) axis to produce Glucocorticoid (cortisol).
We will see later that the difference between adrenaline and cortisol is very important.
How to measure stress
Measuring physiological changes, such as cortisol, adrenaline, blood pressure, and resting heart rate, maybe relevant in assessing acute stress. However, these fluctuate widely, and they may not be suitable to measure chronic stress. Low heart rate variability (HRV) and elevated levels of high sensitivity CRP (hs-CRP) are more accurate markers of chronic stress.
You may not realise that variability in the time between the heartbeats is a sign of health, whilst a fixed time between the beats indicates a high level of stress. And hs-CRP is a sign of low-grade chronic inflammation – the hallmark of metabolic syndrome.
Acute stress results in weight loss, chronic stress in weight gain!
The surprising fact that acute stress results in weight loss, whereas chronic stress prompts weight gain, is because the different types of stress activate the above different metabolic pathways.
In acute stress, high adrenaline results in anorexia, appetite suppression, and weight loss. High adrenaline also causes a catabolic (breakdown) state through its effect on the liver and adipose (fat) tissue. This, together with the anorexigenic (depressed appetite) effect, often results in significant weight loss. I have met many patients who have lost a couple of stones within a few days, after a severe infection like pneumonia or a major surgical procedure.
On the other hand, chronic stress can lead to dietary over-consumption (especially of palatable foods), increased visceral adiposity and weight gain. The obesogenic effect of chronic stress is explained by the chronic release of cortisol.
Bear with me on the science bit because the chemicals here are crucial. Activation of the HPA axis produces cortisol in three steps. The hypothalamus produces a corticotropic releasing hormone (CRH) to stimulate the pituitary to produce Adrenocorticotrophic hormone (ACTH) to stimulates the adrenal gland to produce cortisol. But here’s the rub – CRH, the first chemical produced, also has the effect of stimulating hypothalamus (energy balance centre) receptors to increase calorie intake and cause weight gain. In addition, stress stimulates the selection of calorie-dense, highly palatable foods over healthier options.
In one study, laboratory rats, forced to swim for one hour, lost weight during the first few days of exposure to this stress. Further stress resulted in progressive weight gain. Acute stress moved over to chronic stress. Interestingly, chronic stress-related weight gain occurred despite a reduction in the rats’ food intake.
And the Whitehall 2 study on humans confirmed that chronic job stress was significantly associated with increased obesity, both generally and centrally.
Understanding the pro-obesogenic effect of chronic stress and the anorexigenic effect of acute stress may help us to identify effective options to prevent stress-related adverse metabolic effects.
Chronic stress = obesity = metabolic syndrome
Chronic stress causes a redistribution of body fat stores, resulting in increases in intra-abdominal fat. This contributes to promoting ectopic fat storage in the liver and vascular tissues.
This inevitably leads to metabolic syndrome.
Such redistribution of fat means a fatty liver and increased risk of vascular disease. Belly fat produces inflammatory cytokines, triggering chronic low-grade inflammation and insulin resistance, which are the hallmarks of metabolic syndrome. Deposition of fat in the pancreas is the underlying cause of type 2 diabetes since a fatty pancreas can no longer compensate by producing more insulin to allow more glucose into cells. Resulting in constant high blood glucose and type 2 diabetes.
Stress can also result in PCOS (Polycystic Ovary Syndrome), a condition characterised by abdominal obesity, insulin resistance, high androgens (a male sex hormone), giving ladies excessive hair on their face and body. With PCOS, females exhibit increased HPA activity, together with high insulin.
Low birthweight; deprived childhood
A high concentration of maternal cortisol retards intrauterine growth in humans, producing small babies. However, low birth weight is associated with an increased risk of developing the cardiometabolic disease during adulthood.
In one study, very low birth weight was associated with a significantly increased risk of obesity in adulthood. Another study showed that low birth weight is associated with an increased risk of hypertension and diabetes. And a third one suggested that it might predict the development of PCOS.
Turning to adverse circumstances in childhood, a study showed that individuals who reported several adverse childhood experiences exhibited a 1.4 to 1.6 increase in the incidence of severe obesity as adults. Another study concluded that a harsh childhood environment and lack of socio-economic support predict hypertension in young adults.
Other studies have revealed that jobs with specific stress, as among police officers, increased the prevalence of metabolic syndrome and impacted coronary plaque presence. In this specific occupation, early and comprehensive therapeutic intervention could reduce the overall risk of cardiovascular events and prevent pulmonary function impairment.
One study found that, after 11.5 years of follow-up, a woman who experienced dissatisfaction in her marriage had a three times higher risk of developing metabolic syndrome. Another study based on 216 married couples living in England evaluated marital adjustment and found that, where husbands reported poor marital adjustment, there was a ten times greater risk of their wives having metabolic syndrome. However, the wives’ reports of poor marital adjustment did not have a significant influence on their husbands’ risk of developing metabolic syndrome.
The MIDUS study evaluated strain in relation to family matters among 1,355 men and women, and, after 9.2 years of follow-up, it found family strain to be a risk factor for weight gain among women but not among men.
A high level of stress from daily activities was associated with a weight gain of over 10kg in middle-aged men, but not among men of other age categories and not among women.
In a re-analysis of the Whitehall 2 study’s population, the subjects were stratified according to BMI at baseline. The study found that men with BMI <22 at baseline experienced a weight loss during work stress, whereas men with a BMI >27 showed an increase in weight.
Employees with chronic work stress have more than double the risk of having metabolic syndrome than those without work stress after other risk factors are taken into account. There is evidence for the biological plausibility of psychosocial stress mechanisms linking stressors from everyday life with heart disease.
At work, a feeling of satisfaction was suggested as a protective factor among men, whilst job strain was found to be a risk factor for metabolic syndrome among women. These findings indicate that the sexes might respond differently to stress.
BMI vs WC
Three studies included both BMI (Body Mass Index – mass divided by height squared) and WC (waist circumference) as outcome indicators. They found that the association between stress and adiposity might be dependent on the outcome measure chosen. One study found job strain associated with increased BMI among both men and women but linked with WC only among men.
Three out of four studies available supported some association between stress and the development of dyslipidaemia, which is basically higher LDL (the bad guy) and lower HDL (the good guy.)
What can I do?
The solutions will not be a surprise to you, my friends! Preventing or reversing metabolic syndrome can be achieved by losing weight, exercising regularly, eating a healthy balanced diet, stopping smoking, and cutting down on alcohol, whilst stress-coping mechanisms include deep breathing (pranayama), meditation, prayer, journaling, listening or playing music, alongside the removal, where possible, of the cause of stress.
Please do bear in mind the crucial difference between acute stress and chronic stress, and do try firstly to rectify any issues that cause chronic stress (job, relationships). And remember acute stress is helpful, but chronic stress is harmful.
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The appraisal of chronic stress and the development of metabolic syndrome: a systemic review of prospective cohort studies
Stressful life events and the metabolic syndrome
Stress and metabolic syndrome
The relationship of metabolic syndrome with stress, coronary heart disease and pulmonary function – Police
Role of stress in the pathogenesis of metabolic syndrome
Chronic stress at work and metabolic syndrome: prospective study
Six types of stress and how to manage them effectively
Stressful life events and the metabolic syndrome