We all know that stress is bad for us, but why is it bad? And how does it cause the negative symptoms we experience?
Hypothyroidism, fat gain, high blood pressure, anxiety, depression, brain fog, and low energy are just a few of the negative consequences of prolonged stress.
Stress causes changes in the body through increasing the hormone cortisol. Cortisol is known as our “stress” hormone and it is produced in the adrenal glands. The primary action of cortisol is to increase blood glucose or blood sugar. We need extra glucose for our brain, and our muscles to help us get away from what is perceived as a threat. Our bodies do not care and cannot distinguish between a true threat (i.e. a bear) or the stress from colleagues, kids, work etc.
How does cortisol raise blood glucose?
- Increased Breakdown of Glycogen: In our liver glucose molecules are strung together and stored as glycogen. The Liver contains significant amounts of stored glycogen which is available for rapid release into circulation. Cortisol stimulates the breakdown of liver glycogen stores (1).
- Increased Breakdown of Fat: While this may sound positive what actually happens is your body breaks down peripheral fat and relocate them to visceral fat cells (those under the muscle, deep in the abdomen) (2). Visceral fat is the dangerous fat around the midsection. Its danger is related to the release of proteins and hormones that can cause inflammation, which in turn can damage arteries and enter your liver. This is why visceral fat is associated with an increased risk for cardiovascular disease markers like high triglycerides, high blood pressure and high cholesterol.
- Increased Appetite & Cravings: Because our body wants an immediate source of fuel. Cortisol’s acts to increase appetite and cravings for high-calorie foods. Studies have demonstrated a direct association between cortisol levels and calorie intake (3). Cortisol may directly influence appetite and cravings by binding to hypothalamus receptors in the brain. Cortisol also indirectly influences appetite by modulating other hormones and stress responsive factors known to stimulate appetite.
- Increased Muscle Breakdown:In times of high stress the body will break down amino acids to be converted to glucose, through the process of gluconeogenesis. Cortisol is the major stress hormone that catalyzes this process. We do not want to be breaking down our muscle because this will lower our metabolic rate making it more likely will we store fat. As a side note collagen can be target for spare amino acids. Chronically elevated stress levels increases collagen breakdown which is not good for the aging process!
All the above ways that cortisol elevates blood glucose also leads to fat storage!
Other Negative Effects of Cortisol
- Increased Bone Breakdown: Cortisol acts to reduce bone density by inhibiting osteoblast (bone making cells) formation and cell proliferation. This dramatically decreases bone building and lowers bone density increasing risk for osteopenia and osteoporosis.
- Decreased Secretory IgA: IgA is an immunoglobulin that coats our digestive track. It has a really important role to keep us protected from gut infections and dysbiosis. Decreased secretory IgA is seen in leaky gut or intestinal permeability as well as in chronically stressed individuals (4). As as result of leaky gut, not only are foods not being properly broken down, they are getting through into the bloodstream. This results in food sensitivities and inflammation which in turn further elevates cortisol.
- Increased Th2 Immune Response: Our immune system response can be divided into two legs. The TH1 leg our humeral response and Th2 leg is our cell mediated response. Both legs are important for protecting us in different ways and must be balanced. Chronic stress elevates the Th2 response, the antibody producing side of our immune system, and lowers the Th1, the anticancer, anti-infectious side. This is not good news if you have leaky gut because now we have more of the immunoglobins or antibodies to react with those food particles that are getting through into the blood stream.
Cortisol impacts on the Brain:
- Reduced Hippocampus Size: The hippocampus is an area in the brain which is responsible for converting short to long term memory. Chronic stress has been shown in rats to reduce hippocampus size and functioning(6). In Alzheimer’s disease, the hippocampus is one of the areas to suffer damage. It has been hypothesized that because chronic stress damages the hippocampus it may contribute to the development of Alzheimer’s disease or short-term memory loss and disorientation.
- Decreased Frontal lobe activity: The frontal lobe is important for our personality, problem solving, memory, initiation, judgement, impulse control, and social and sexual behaviour. Chronic stress reduces frontal lobe activity which can lead to anxiety, depression, as well as difficulty with concentration and memory (7).
As you can see the effects of chronic stress are complex. Stress reduction is more important than ever as we are faced daily with obstacles in our environments. Stress can be from emotions, over exercise, under eating, chronic disease, inflammation, gut imbalance, toxicity, and much more. This is why measuring your cortisol response throughout the day as well as stress reduction should be apart of your daily routine!
- “Endocrine Core Notes”. Rose-hulman.edu. N.p., 2017. Web. 11 Apr. 2017.
- Epel ES, McEwen B, Seeman T, et al. Stress and body shape: Stress-induced cortisol secretion is consistently greater among women with central fat. Psychosom Med. 2000;62(5):623-632.
- Epel E, Lapidus R, McEwen B, Brownell K. Stress may add bite to appetite in women: A laboratory study of stress-induced cortisol and eating behavior. Psychoneuroendocrinology. 2001;26(1):37-49.
- Phillips, Anna C., et al. “Stressful life events are associated with low secretion rates of immunoglobulin A in saliva in the middle aged and elderly.” Brain, behavior, and immunity 20.2 (2006): 191-197.
- Elenkov, Ilia J. “Systemic stress-induced Th2 shift and its clinical implications.” International review of neurobiology 52 (2002): 163-186.
- Murakami, Shuji, et al. “Chronic stress, as well as acute stress, reduces BDNF mRNA expression in the rat hippocampus but less robustly.” Neuroscience research 53.2 (2005): 129-139.
- Arnsten, Amy FT. “Stress signalling pathways that impair prefrontal cortex structure and function.” Nature Reviews Neuroscience 10.6 (2009): 410-422.