Steroid Hormones Part 2: Cortisol and Stress


Cortisol is made in the adrenal cortex. It is primarily known for its role in our stress response by engaging the sympathetic nervous system (better known as “fight or flight”). Here’s the basic mechanism: We see a tiger. We need to run. In order to run we need energy. To have energy we need blood sugar. This is one of the functions of cortisol. It gets sugar into the blood stream so we can run from the tiger. The problem is when there really is not a tiger and no running is happening.

If we are constantly under stress, we keep getting the “run signal.” This pumps sugar into the blood stream. On the other side of the equation is insulin. Insulin’s job is to move sugar out of the blood and into cells, primarily to be used to produce energy. However, when there is not the need for energy the sugar needs to go into “storage.” We know that as fat. So, at the end of the day, and particularly when in excess both cortisol and insulin are fat storing hormones. They follow a simple rule. When cortisol goes up in your body, insulin will rise. When insulin rises, cortisol will go up with it. The same concept works the other way.

This is why stress management is so critical and why constant stress will lead to weight gain. It is also important to know that constant increases in cortisol will also cause decreases in thyroid hormone production and increases in estrogen production (more on that later).

To summarize the main activities of cortisol:

For the nervous system it manages our sympathetic response and plays a role in healthy mood and emotions.

For blood sugar management it recognizes when we need energy. When blood sugar levels become low through our normal activities it is role of cortisol to take action. It happens all day long. The problem becomes when we remain in a stress response. This ongoing excess can ultimately contribute to insulin resistance.

For the immune system in a normal mode it supports a healthy anti-inflammatory response. However, at high levels it can be immunosuppressive while at low levels the immune system may be unable to engage effectively.

It is interesting that as a steroid hormone cortisol has catabolic (state of breakdown); anabolic (rebuilding); and anti-inflammatory functions.

It is clear from the above discussion there are many adverse effects of high and prolonged stress. We will discuss some of these later in more detail, but for a quick short list consider the following implications of increased cortisol:

• Reduces fertility by lowering luteinizing hormone which impacts ovulation in females and testosterone production in males.

• Reduces the active thyroid hormone T3 as increased cortisol increases rT3 which suppresses T3.

• Creates estrogen dominance (to be discussed in more detail later in females and males.

• Decreases DHEA.

• Suppresses the immune system.

Bernard Rosen, PhD is a Nutrition Consultant and Educator. He works with individuals, groups, and at corporations to create individualized nutrition and wellness programs. His office is in Coeur d’Alene, ID. To learn more or to schedule an appointment, e-mail at, call (208) 771-6570 or go to