What Is Cortisol, and Why Does Managing It Matter for Health?

Cortisol has many important functions that help the body respond to stress. But, chronic stress—leading to excess cortisol—makes it more difficult to control blood sugar levels, manage your weight, and maintain optimal health.

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Danielle Kelvas, MD
— Signos
Medical & Health Writer
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Updated by

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Science-based and reviewed

May 17, 2024
June 16, 2022
— Updated:
June 17, 2022

Table of Contents

I often have patients who come to me apologizing for feeling stressed. I tell them it's okay and that they shouldn't be so hard on themselves. Stress is a common feeling and they're not alone in experiencing it. Practicing self-compassion can go a long way in helping to ease stress levels.

Our nervous systems and endocrine systems have not evolved to handle the unique stresses that modern humans face on a day-to-day basis. We live with chronic 21st century syndrome—a series of daily events that cause us to feel perpetual stress. “In other words, that stressed-out feeling that you have everyday may be typical because everyone experiences it, but it is not normal in a physiologic sense, nor is it associated with good health,” says Dr. Shawn Talbott, Ph.D., Psychonutritionist.

Stress can spike blood sugar levels, which can lead to weight gain over time. But, lowering stress is not as simple as telling yourself to calm down, because stressing about stress creates even more stress. That's a lot of stress!

My hope for this article is that it will empower you to better manage your blood sugar. I don't want to add to your stress levels, but I do want to encourage you to be mindful of any feelings of guilt, shame, or failure that may arise as you read about how stress and blood sugar interrelate.

Cortisol, the "stress hormone," regulates the body in many ways, similar to how musical instruments work together to create a symphony. This system is a fascinating and powerful defense mechanism, but when it is overused, it can lead to unwanted health outcomes.

With awareness of how cortisol works, you can lower your stress levels and better regulate your blood sugar.


What Is Cortisol?

Cortisol is most commonly known as the body’s stress hormone. It is produced from cholesterol molecules within the adrenal glands (the zona fasciculata layer to be exact) and regulated by the hypothalamic-pituitary-adrenal (HPA) axis.1

In simpler terms, cortisol is produced in the kidneys.

The amygdala—a section of the brain—processes our feelings of arousal, fear, and emotion.2 When stressful situations arise, the amygdala (brain) activates the HPA axis (pathway), which controls when, how, and how much cortisol the body produces and secretes into the body. 

There are diseases where enzymes in the HPA axis do not function properly, such as cortisol excess disorders, like Cushing syndrome, or cortisol insufficiency, like Addison disease.

Cortisol affects nearly all organ systems, because receptors exist on nearly every tissue within the body, including:3

  • Nervous
  • Immune
  • Cardiovascular
  • Respiratory
  • Reproductive
  • Musculoskeletal
  • Skin (integumentary)

This is why when someone feels stressed, you may experience any of the following:4

  • Increase in heart rate and blood pressure
  • Hair stands on end
  • Clenching feeling in your stomach (resulting in diarrhea or nausea and/or vomiting
  • Headaches 
  • Brain fog, anxiousness, or crowded thoughts
  • Shortness of breath
  • Women may miss a menstrual cycle or have difficulty conceiving.

In response to all of these physiological changes, cortisol causes cells to release blood sugar into circulation to ensure all of the body’s systems have enough energy. Afterwards, you may experience negative feelings that come with blood sugar spikes (hyperglycemia).

<p class="pro-tip"><strong>Learn about </strong><a href="/blog/mitigate-high-glucose-spikes">how to mitigate blood sugar spikes</a></p>

What Impacts Cortisol Levels?

Cortisol activates in the body during a fight or flight situation. The nervous system is divided into several parts, two of which are called the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). They balance each other to keep us safe, healthy, and able to respond to threats quickly and efficiently. 

From an evolutionary perspective, when under attack by a predator, the HPA axis immediately sounds the alarm; allowing us to fight, flight, freeze, or flee before our conscious awareness can respond. 

This is why when someone burns themselves on the stove or sees a car swerving into their lane, the body reacts instantly, before we can tell ourselves to withdraw our hand or slam on the break. Being able to move and react quickly requires enormous amounts of energy and sugar (glucose). 

Next time this happens, notice how flushed you may feel—part of this is from cortisol and epinephrine coming to your rescue!

How Does Cortisol Function In the Body?

When explaining things to patients, I often draw diagrams. For our more visual learners, I’ve drawn the hormone diagram below. When an emotional stimuli activates the amygdala within the brain, it sends a message to the paraventricular nucleus (PVN) within the hypothalamus5. This begins the activation of the HPA axis.

The hypothalamus releases a hormone called corticotropin-releasing hormone (CRH), which travels to the anterior pituitary gland (another region within the brain). The anterior pituitary gland releases a hormone called adrenocorticotropic hormone (ACTH), which travels down to the adrenal glands. This triggers the adrenals to release cortisol, which then activates the rest of the body. High levels of cortisol trigger a negative feedback loop so the brain knows when to taper down levels of CRH and ACTH. 

This diagram illustrates the stress response mechanism.

Cortisol does much more than just activate the flight or fight response—it:

We get a boost of cortisol in the morning to help start the day, but when it is chronically high due to ongoing stress, cortisol can have negative health effects.

<p class="pro-tip"><strong>Learn about </strong><a href="/blog/glucose-metabolism">glucose metabolism and why it's important</a></p>

Why Is Cortisol Management Important for Health and Weight?

Cortisol functions in part by keeping enough blood sugar in circulation to feed the brain, among other organs. It decreases secretion of insulin and uptics levels of glucagon—which help the body to function normally during times of intermittent stress. 

<p class="pro-tip"><strong>Learn about </strong><a href="/blog/optimize-your-brain-health">how to boost brain health</a></p>

Because many of us live in perpetual stress, cortisol can cause moderate to severe weight gain and blood sugar oscillations.

three women riding bikes on a forest trail
Spending time with friends and getting exercise are good ways to manage stress.

Weight Management

For those with pathologically high levels of cortisol—such as from Cushing’s disease and syndrome—symptoms include weight gain; especially in the face, abdomen, and between the shoulders.6 This is commonly referred to as a buffalo hump. In people with diabetes, chronically high levels of stress make controlling the disease much more difficult.7

<p class="pro-tip"><strong>Learn more about </strong><a href="/blog/hormones-and-weight-loss">hormones and weight loss</a></p>

High Blood Pressure

Cortisol also contributes to high blood pressure (hypertension), brittle bones (osteoporosis), and male pattern hair growth in women; especially on the face (hirsutism). 


Insomnia and sleep disturbance can be further exacerbated by unstable cortisol levels. In a healthy, low-stress state, the body naturally releases a light burst of cortisol in the morning that steadily decreases throughout the day.8 It drops to its lowest level typically around midnight. Disrupting cortisol and circadian rhythms can indirectly affect other hormones that impact blood sugar, such as growth hormone.9 Studies have well demonstrated the link between poor sleep and weight gain.  

Read next: How to Manage Stress and Cortisol Levels

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  2. Hakamata Y, Komi S, Moriguchi Y, Izawa S, Motomura Y, Sato E, Mizukami S, Kim Y, Hanakawa T, Inoue Y, Tagaya H. Amygdala-centred functional connectivity affects daily cortisol concentrations: a putative link with anxiety. Sci Rep. 2017 Aug 16;7(1):8313. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5559590/ 
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  7. Diagnosis and classification of diabetes mellitus. Diabetes care. 2009 Jan. [PubMed PMID: 19118289]. https://pubmed.ncbi.nlm.nih.gov/19118289/
  8. Geiker NRW, Astrup A, Hjorth MF, Sjödin A, Pijls L, Markus CR. Does stress influence sleep patterns, food intake, weight gain, abdominal obesity and weight loss interventions and vice versa? Obes Rev. 2018 Jan;19(1):81-97. Epub 2017 Aug 28. PMID: 28849612. https://pubmed.ncbi.nlm.nih.gov/28849612/ 
  9. Ottosson M, Lönnroth P, Björntorp P, Edén S. Effects of cortisol and growth hormone on lipolysis in human adipose tissue. J Clin Endocrinol Metab. 2000 Feb;85(2):799-803. doi: 10.1210/jcem.85.2.6358. PMID: 10690893. https://pubmed.ncbi.nlm.nih.gov/10690893/

About the author

Dr. Danielle Kelvas, MD, earned her medical degree from Quillen College of Medicine at East Tennessee State University in Johnson City, TN.

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