How Stress Causes Insulin Resistance: Cortisol Effects
Stress is known to be responsible for many failures in the body, chronic diseases, acute or chronic conditions including insulin resistance. It's not just a general opinion or hypothesis. There is a very distinct biochemial mechanism behind that powered by cortisol, a major stress hormone secreted by adrenal glands because one of primary functions of cortisol is raising glucose levels in the blood stream.
How Cortisol Works
Cortisol enhances bodily functions and processes critical for survival in a stressful situation and on the other hand, temporarily curbs non-essential processes that might use those vital resouces or even be harmful in the situation.
Throughout the development of humankind 'the stress' has been a situtaion of an immediate hazard or when one needs to quickly enhance all the body's resources, both physical and mental, for survival or successful completion of a task critical for survival. Examples are fight, natural disasters, hunting, getting food. However, these sutuations are temporary and as soon as the stressful factor is gone cortisol and glucose levels get back to normal as there is no loner need for the abnormal use of the body's resources and the balance (homeostatis) would soon be restored. In fact, researchers agree that the short-term moderate stress is not harmful but on the contrary, helpful and healthy. First, it increases a person's resistance to stressful situations and educates them. Second, it stimutales personal development. The successful resolution stimulates the the work of 'reward neurotransmitter' dopamine in the brain zome called nucleus accumbens and the signals from that area reach the cortex creating permanent neural networks or the memory about things that are 'enjoyable and doable or attainable'.
Today, the stressful factors changed a lot due to the achievements of the civilized world and changes in human reasoning which became more complicated and, at the same time, more open to stressful infomation from numerous sources. So, instead of short term exposure to fight-or-flight response people suffer from anxiety and prolonged background stress due to uncertainty about the futue, financial trouble and planning, troubles at work, bad expecttions or prognosis, worldwide crisis, local and worldwide bad news , potential health issues, etc. As a result, the prolonged work of cortisol in the background, sometimes for years or even decades, results in health issues even in seemingly healthy people living a healty lifestyle and eating a healthy diet. In particular, because glucose metabolism and homeostatis get impaired by cortisol.
How Cortisol Raises Blood Sugar
Whenever blood sugar rises too high after having a meal the pancreas starts producing insulin and in response to insulin the liver starts storing the excessive glucose as glycogen, a starchy sugar. Glycogen is later released back into the blood stream to provide the energy in fasting periods. For this to happen, in response to blood glucose getting to low the pancreas stops secreting insulin and starts producing another hormone - glucagon. However, cortisol forces the liver to release glycogen 'over and above the plan' eleveating blood sugar even if there is enough in the blood stream for the moment.
In the scope of cortisol-glucose relationship, muscle catabolosim is an unhealthy way of getting glucose for the body as a result of muscle protein breakdown. For this reason cortisol is also known as a catabolic hormone. Muscle catabolosim is often observed under stress caused by injury or burns, during infection, system inflammatory processes or even long exhausting unbalanced workouts. Other stressful situtations, including starving, may also put metabolism on catabolic rails. Prolonged catabolic process of this kind is perilous not just for the muscle but may also cause kidney damage.
Inhibiting insulin production
Cortisol curbs secretion of insulin by the beta cells of the pancreas.
Cortisol and Starving
Starving (as opposed to a healthy or low-glycemic diet) is not just useless but harmful in case or diabetes or insulin resistance. This is a stressful condition triggeresing the production of cortisol, which, in its term, does its best to maintain high glucose levels in the blood resorting to the above mechanisms. For this reason, people alternating regular starving periods with eating high calory foods may only observe fat accumulation. In fact, people with a genetic condition called Cushing syndrome where cortisol is produced in excessive amounts suffer from excessive abdominal fat (adipose tissue).
Naturally, persons with an impaired pancreas function or elevated blood sugar will suffer from the adverse effects of cortosil sooner that the patients with non-impaired sugar metabolism as their insulin levels are insufficient to compensate for the action of cortisol.