4 Facts About Cortisol You Should Know

What is cortisol and how does it affect me?

If you have not heard of cortisol, you are probably not alone. Unlike insulin, testosterone, and estrogen, cortisol is a relatively unsung hormone. However, cortisol plays an important role in human health. Here are four facts about cortisol that you need to know about:


Cortisol is produced through the interaction of the hypothalamus, adrenal glands, and the pituitary gland. The hypothalamus is a region in the brain that links the endocrine system and the nervous system. That is, the hypothalamus takes signals from the brain and tells the endocrine system what it needs to do in response to what the brain is experiencing.

There is no better example of this interaction than cortisol. Cortisol is sometimes referred to as the “stress hormone” because the hypothalamus sends a signal to the adrenal glands to release the hormones cortisol and adrenaline when you’re experiencing an emergency. This is the body’s way of preparing you for “fight or flight.” Adrenaline makes your heart rate, respiration, and blood pressure increase. Cortisol signals the liver to convert stored glycogen into glucose and release the glucose into the blood, thereby raising blood sugar levels. Combined, this stress response puts your body in the perfect condition to either battle or run.

Cortisol is also released under normal, non-threatening conditions. In fact, cortisol levels vary throughout the day and night, leading endocrinologists to believe that its cyclic production is related to daily activity levels.

When cortisol levels are low, the hypothalamus produces corticotrophin-releasing hormone. This hormone is sensed by the pituitary gland, which produces adrenocorticotropic hormone. In response to this hormone, the adrenal gland secretes cortisol into the bloodstream. This is a negative feedback loop. When the cortisol levels rise, the hypothalamus and pituitary gland stop producing their hormones, shutting down cortisol secretion by the adrenal gland.


As noted above, cortisol signals the liver to release glucose into the bloodstream. In this respect, cortisol is the opposite of insulin, which signals the liver to remove glucose from the bloodstream. The discovery of insulin earned scientists Frederick Banting and John Macleod the Nobel Prize in Medicine in 1923. In addition to acting as a chemical signal to the liver, cortisol also prevents inflammation in the muscles, helps your brain form memories, and balances salt and water levels in the body.

Excess Cortisol

Too much cortisol can be associated with weight gain due to cortisol’s effect on blood sugar. Thus, a personalized weight loss program may require that an endocrinologist address a cortisol imbalance.

Specifically, cortisol prompts the liver to release glucose into the blood stream. But when this glucose goes unused (since we rarely fight or flee anymore), it can be stored as fat. Moreover, cortisol levels have been linked to appetite via the hypothalamus. One theory is that the stress response makes us hungry after it subsides so we can replenish the glucose stores that should have been depleted by fighting or fleeing.

Endocrinologists also suspect a link between Type II diabetes and high cortisol levels. Type II diabetes is caused when the cells of the pancreas responsible for producing insulin “burn out” from overuse because the muscle, fat, and liver cells have become insulin-resistant. Since cortisol acts as the opposite of insulin, high cortisol levels can cause muscle, fat, and liver cells to ignore or resist insulin, thereby leading to Type II diabetes over time.

Finally, there is a disorder diagnosed by endocrinologists that is specifically caused by high cortisol levels called Cushing Syndrome. Cushing is characterized by:

  • Weight gain
  • Bruising and stretch marks on skin
  • High blood sugar
  • Osteoporosis
  • Anxiety and depression
  • Suppressed immune system

Cortisol Deficiency

Too little cortisol can have equally severe effects. A deficiency of cortisol can be caused by disorders of the pituitary gland or Addison’s disease. Symptoms of a cortisol deficiency can include:

  • Fatigue and muscle weakness
  • Nausea and dizziness
  • Weight loss
  • Low blood pressure
  • Darkening of skin regions such as scars and skin folds
  • Depression

Cortisol is essential to proper function of many of the body’s systems, including metabolism. However, too little or too much cortisol can be dangerous or even fatal. For more facts about cortisol, rely on Dr. Philip Rabito today.

Philip Rabito, MD

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