HOW CHRONIC STRESS DRIVES METABOLIC DISEASE
Persistent exposure to stress is strongly linked to an increased risk of various metabolic diseases, including type 2 diabetes mellitus, obesity, and cardiovascular disease.
Furthermore, stress is also a contributor to metabolic syndrome, a cluster of symptoms including hyperglycemia, excess body weight, high cholesterol, and other forms of dyslipidemia that increase the risk of the above-mentioned conditions.
While there's a lot we don't know about metabolic disease, we know that lifestyle can play a significant role. In addition to stress management, diet and physical activity largely play into the positive or negative outcomes of these conditions.
In this article, we'll take a look at what happens in a stress response, how it impacts your metabolic health, and what you can do to start managing your stress and give your nervous system a much-needed break.
What Happens In The Stress Response?
Your stress response is a highly complex series of chemical reactions that take place to protect you from life-threatening situations. This innate response gave your ancestors an edge when they were living in the wild, but today the same chemical cascade that may very well be responsible for the survival of the human race – has now become one of the greatest threats to our livelihood.
Because what was meant to act as a short-term response to threatening circumstances is now a chronic issue in our society. Your ancestors' stress response likely worked very similarly to that of animals. They encounter a threat, the stress response ignites, they fight off the predator or flee from the situation, and then the stress response calms down.
Today, our stressors are so prominent in our lives that we seldom get a chance to "turn it off." Instead, people find themselves chronically stressed – to the point where they don't even remember what it feels like to be without stress.
Let's take a look at what happens physiologically in the stress response:
When you encounter a stressor (i.e., your boss, financial strain, health issues, and so on), your body turns on a two-part stress response.
First, you experience "fight or flight" mode, which is your immediate response. This fight or flight comes from the activation of your sympathetic nervous system, which elicits a response from the sympatho-adrenomedullary (SAM) system.
Once activated, this rapid response initiates the mobilization of energy in your body by promoting the breakdown of glucose in your liver while simultaneously increasing glucose production. It also increases your heart rate and blood pressure and directs blood flow away from your internal organs to your limbs. All of these actions are meant to facilitate successful survival by giving your body the energy and blood flow it needs to fight or flee.
Next, your body elicits a slow yet more amplified and sustained response that comes primarily from your adrenal cortex and the glucocorticoids it releases.
In this phase of the stress response, fuel mobilization becomes more sustained with the release of free fatty acids from your fat tissues and even more glucose production from your liver. Meanwhile, glucocorticoid signaling decreases insulin production while increasing insulin resistance, promoting greater glucose availability in your blood. You can think of this phase as your body's way of getting as much usable fuel into your circulation as possible.[3,4]
Under normal circumstances, glucocorticoids create a feedback loop that eventually shuts down both phases of the stress response, allowing your body to settle back into homeostasis once the threat is gone.
In a chronic stress response, however, these systems get pushed so frequently that the regulatory circuits put in place to create a feedback loop becomes dysregulated. As a result, your response to stress becomes more excitable, and your body's innate ability to shut it down loses its power.
Chronic Stress and Metabolic Disease
As you might imagine, a sustained stress response can wreak havoc on the body, driving oxidative stress and inflammatory processes. While these responses may be adaptive in the short term, long-term exposure to stress chemicals leads to "wear and tear" on your organs and tissues and can set the stage for disease. And since the stress response is so heavily involved in fuel mobilization, one of the systems that takes the greatest hit is your metabolic system.
Specifically, research shows that chronic stress can create dysregulation that sets the stage for:
- Cardiovascular Disease
- Type 2 Diabetes
Let's dive a bit deeper.
Appetite and Obesity
In an acute stress response, your appetite generally shuts down as you have bigger issues to deal with than what's for lunch; however, due to the energy-intense nature of stress, once the response becomes chronic, your body shifts, and it starts looking for fuel to ensure that you'll have enough energy to fight or flee. This is partly due to glucocorticoids regulating food intake and fat storage.
In an effort to make food a priority, stress stimulates cravings for calorically dense, highly palatable foods, as opposed to more nutritious options, by instigating reactions in your brain's reward system. Now your brain is wired for unhealthy choices that will provide a short-term reward and an excess of calories.
And where do all of those excess calories go? Unless you're actually running from a predator, they get stored as fat in your adipose tissue. And to make matters worse, most people find that the fat they store from the stress response lands primarily in their abdomen – increasing their waist circumference and putting them at risk for metabolic disease.
Now there's actually a very good biological reason that stress-induced fat is stored in the visceral tissues. Of all your fat tissues, your visceral tissues are believed to respond most rapidly to the call for free fatty acid release when the stress response hits. Therefore, your body is wisely trying to store as much extra fat in the abdomen as possible in case you encounter another predator.
Oh, sweet, misguided body.
The connection between cardiovascular disease and the stress response is a bit less-linear than that of obesity, but there is still solid evidence indicating the increased prevalence of poor cardiovascular outcomes when chronic stress is present. For example, research shows that:
- People working in high-demand, low-reward jobs tend to have higher rates of cardiovascular disease and an accelerated progression of endothelial dysfunction and atherosclerosis due to work-related stress.
- Marital stress among working women is associated with a 2.9-fold increase in the risk of coronary heart disease.
- Spousal caregivers of patients with Alzheimer's disease exhibited higher plasma lipids (specifically triglycerides) and increased blood pressure compared to non-caregiver controls.
While some evidence suggests that these cardiovascular outcomes may result from stress-induced poor food choices, there is likely more to the story.
For example, chronic exposure to elevated glucocorticoids is associated with hypertension and atherosclerosis in Cushing disease patients, indicating the role of the stress response chemicals.
Type 2 Diabetes
Type 2 diabetes is marked by defects in both insulin secretion and insulin action on cells (cells become resistant to insulin).
In a chronic stress response, glucocorticoids can promote insulin resistance by dimming the effect of insulins signal on your cell receptors. This helps to keep glucose in the blood for longer periods. This could compound the situation for someone who already has diabetes and, therefore, trouble regulating and utilizing this hormone. For example, research shows that acute exposure to psychosocial stress in diabetic subjects impairs glucose clearance after meals.
Furthermore, the central weight gain common in chronic stress may further exacerbate the progression of diabetes since stress is often associated with low-quality food choices that may promote central fat storage.
Polycystic Ovarian Syndrome (PCOS) is a complex endocrine and metabolic disorder that's characterized by insulin resistance, hypertension, ovulatory dysfunction, hyperandrogenism, and increased abdominal obesity.
Of course, we've already covered how stress can impact abdominal obesity and insulin resistance, but research shows that stress may have an ever deeper root-cause impact on PCOS. In fact, research shows that many of the symptoms associated with PCOS may be due to defects in the SAM and adrenal stress pathways.[15,16]
Human studies have found it difficult to parse out whether the symptoms of PCOS cause increased stress hormone dysregulation or if stress dysregulation causes PCOS in the first place. Since PCOS is a common cause of infertility among women, there is a significant amount of emotional pain and stress that can come with this diagnosis.
With that being said, animal studies show that despite the lack of psychosocial stress that humans would feel, rats with PCOS still exhibit increased SAM and adrenal hormone activity along with ovarian dysfunction.
4 Tips For Effectively Managing Stress
Managing stress is often much easier said than done – but the more energy you put towards mitigating the impact that stress has on you, the healthier you will be. While it would be impossible to remove stress from your life entirely, there are many things you can do to reduce the amount of stress your body has to process.
Below are four science-backed ways to mitigate stress and create more resilience.
Physical activity is one of the quickest ways to relieve the overwhelming feelings that come with stress. Moving your body reduces stress hormones like adrenaline and cortisol while stimulating the production of endorphins, which are chemicals in your brain that naturally elevate your mood. Ever experienced a runner's high? That results from the surge of endorphins flowing through your body.
Studies show that higher cardiovascular fitness levels are associated with reduced anxiety and depression. In one trial, six weeks of aerobic exercise resulted in significant improvements in feelings of depression, reduced overall perceived stress, and a better ability to cope with uncertainty. Overall, research shows that when you're physically active, it can act as a buffer against mental health issues and improve feelings of well-being.
Meditation is becoming one of the most popular stress-reduction strategies out there, and for a very good reason. When you meditate, especially in the practice of mindfulness meditation, it trains your attention and allows you to consciously create more space in your mind when stressful thoughts start to emerge. As opposed to shoving away unwanted feelings, meditation allows you to open up and work with uncomfortable feelings in a way that makes them less scary.
Studies show that mindfulness exercises can increase subjective well-being, reduce emotional reactivity, and improve behavior regulation – all while helping to reduce feelings of overwhelm and stress.
Furthermore, mediators tend to display higher levels of overall mindfulness and self-compassion. In turn, this reduces behaviors like rumination, thought suppression, and fear of emotion.
Some research even suggests that people who meditate regularly may show a reduction in their fasting glucose levels.
Beginning a meditation practice is much easier than you may think, with even ten minutes per day of mindfulness creating meaningful changes in your brain.
As you learned, when your body is in the fight or flight response, your body responds by increasing fuel availability, pumping up your heart rate, and quickening your breath. All of these reactions are meant to help you fight or flee.
On the other hand, when your body is relaxed, your breathing slows down, your heart rate becomes more steady, and blood flow returns to your internal organs.
Interestingly, research shows that you can effectively "trick" your body into thinking that you're relaxed by slowing down your breathing. A specific type of breathwork called diaphragmatic breathing has been studied for its ability to move your body out of sympathetic mode (fight or flight) and into parasympathetic mode (rest and digest).
When you take deep, belly breaths, it signals to your body that you're safe, lowering cortisol levels and improving feelings of well-being. It also makes you generally less reactive and helps to calm centers in your brain that are wired for fear. Furthermore, deep breathing has been shown to stimulate GABA pathways, which is a neurotransmitter that reduces excitability in your brain, helping you to control feelings of fear and anxiety.
A simple deep breathing exercise is to slowly breathe in for a count of four, hold it for a count of three, and then breathe out for a count of seven.
Community provides a very important and unique source of stress relief due to the impact of social support. Social support has been described as "support accessible to an individual through social ties to other individuals, groups, and the larger community.”
Studies show that high social support reduces the risk of depression, lowers levels of the stress hormone cortisol, and enhances your overall resilience to stress. Having a community that you can rely on is essential for maintaining both physical and psychological health.
In fact, the effect of social support (or lack thereof) on life expectancy is as strong as the effects of obesity, hypertension, and cigarette smoking. When you have a solid community backing you up, it can improve health in more ways than you could imagine.
This may be due in part to the effect of the hormone oxytocin. When you feel connected to others in a community, it simultaneously dampens cortisol activity while increasing oxytocin – the love hormone that makes you feel safe and connected.
Several risk factors can contribute to metabolic diseases, but the role of stress should not be taken lightly. Psychosocial factors have proven to be detrimental to health outcomes in various conditions, and due to the impact that your stress hormones have on metabolic activity, stress (or lack thereof) can be considered a strong predictor for health outcomes.
As the incidence of metabolic conditions continues to grow in the US and worldwide, the hope is that healthcare practices start putting a focus on how we manage our stress.
To learn more about metabolic disease and how you can shift your lifestyle to create optimal outcomes, check out the BioCoach App.
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