We all know that too much stress is unhealthy. We are in a bad mood, don’t sleep well, retain water and have food cravings all the time.
But why does stress, or rather the hormone responsible for this, Cortisol, affect our body this way?
As I explained in the first part of this series, Cortisol is released in the “Fight or Flight” situation and shuts down all “unnecessary” processes of our body that use too much energy. Its main function is to allow our brain to fully concentrate on the stressful situation that could possibly risk death and solve this as quickly as possible.
Make sure to check out the other parts of this series:
Part 1: Meet your Stress Hormones
Part 2: How Cortisol affects your body
Part 3: Does stress inhibit weight loss?
Part 4: Why stress makes you sick
Part 5: Food for stress relief
Part 6: Exercise to relieve stress
How cortisol affects your body
The effects of cortisol on our metabolism are complex.
In the early stages, cortisol actually activates anti-stress and anti-inflammatoric pathways. Also, it increases the formation of glucose from our body’s glycogen stores, mostly in our liver. This glucose can then be used as energy to solve the stressful situation.
However, prolonged periods of high cortisol levels show the opposite effect:
Cortisol now increases glycogenesis, thus more glucose (carbohydrates) is stored in our liver. Also, it activates proteolysis (breakdown of muscle tissue), reduces bone formation and increases risk of osteoporosis. In fact, high levels of Cortisol decrease absorption of calcium in our small intestines. Thus, even if your nutritional intake of calcium is sufficient, it cannot be used to build up your bones and prevent or heal osteoporosis.
Have you ever wondered why you retain water and feel “puffy” when you are stressed? Cortisol triggers transport of potassium out of our cells, in exchange for sodium. As a result, the high levels of sodium in our cells trigger water influx and you feel bloated and swollen.
Lastly, Cortisol down regulates the synthesis of collagen. This is an amino acid vital for structural support in our muscles, joints and connective tissue.
The effects of Cortisol on our immune system are the main reason high levels of cortisol damage our health.
It prevents the release of cytokines, small molecules activating our immune system and inflammation in our body. While this can be helpful to treat chronic conditions such as rheumatic diseases or any kind of autoimmune disease, it also down regulates the part of our immune system we want to be strong and very active.
To keep it short, there are two parts of our immune system. One of them is regulated by specific cells, called T-cells and B-cells, producing anti-bodies to fight potentially dangerous cells and bacteria. This is also the part that can become overly active in autoimmune diseases and needs to be tamed with Cortisol to prevent our immune system from attacking our own body.
In contrast to that, there is the natural part of our immune system, fighting bacteria, viruses, cancer cells, parasites etc. These cells are our body’s weapon against infections and should be as active as possible.
However, Cortisol down regulates both parts of our immune system. Thus, while decreasing general inflammation in our body, it will also leave us weak and prone to simple infections. This is the reason you get sick so often when you are stressed.
Cortisol also decreases the speed of wound healing. This makes sense, as healing your wounds takes too much energy and time that your body needs to solve that stressful situation.
Electrolyte and water balance
As I explained above, Cortisol decreases potassium levels in our cells. In addition to that, Cortisol acts as a diuretic and increases water diuresis, sodium retention and potassium excretion in our kidneys, as well as sodium and water absorption. This throws off our body’s electrolyte and water balance and can contribute to weight gain and a bloated body.
Cortisol increases gastric acid secretion. Thus, patients having to take Cortisol to treat their autoimmune conditions should always take some medications to protect their stomach lining. Otherwise, many patients develop ulcers, leading to chronic conditions such as gastritis.
Cortisol and Adrenalin work together and improve memories of short-term emotional events. Those “flash bulb memories”, such as the memory of a feeling, a certain picture or taste, could be vital to remember dangerous actions to avoid in the future. However, prolonged levels of increased Cortisol damage cells in our hippocampus, the centre of memory and learning in our brain. This speeds up the aging process of our brain.
Sleep, stress, depression
The highest natural levels of Cortisol can be found in the early morning hours, typically as the sun rises. Then, it reaches its lowest level at around midnight to 4 a.m. before it increases again. When we get tired and want to sleep is mostly regulated by daylight/night cycle that our eyes recognize. However, people with disturbed regulation of Cortisol release (mainly in the hypothalamus area), experience abnormal sleeping patterns, increased risk of depression and psychological stress.
Cortisol production is vital for the proper development of fetal lungs. In fact, it is the high levels of Cortisol in your baby’s body that signals the mother’s brain to initiate birthing. However, high levels of Cortisol in early stages of pregnancy can short-cut the proper development of the fetus, leading to alterations in prenatal and postnatal growth patterns.
Cortisol counteracts Insulin and increases blood glucose levels. In addition to that, it inhibits metabolic processes to use Glucose as fuel and thus contributes to Insulin resistance. This is one of the main reasons high Cortisol levels increase the risk of development of type 2 Diabetes and obesity. I will explain this point in detail in the next articles.
Lastly, researchers have found that prolonged high levels of Cortisol increase risks of cardiovascular diseases, such as Hypertension, truncal obesity, hyperglycemia, insulin resistance, and dyslipidemia.
This is a short overview of the effects of Cortisol in our body. In the next articles, I will further explain Cortisol’s role in Weight Loss, Cancer development and Diabetes. If you would like me to explain another health factor more explicitly, please let me know!