End Fatigue Today: Thyroid, Insulin and Cortisol.

End Fatigue Today: Thyroid, Insulin and Cortisol.
Photo credit: istockphoto/jyllana

Do you feel that your energy is out of balance, and you are unable to beat fatigue?

Does your fatigue leave you with little left for family, spouses, children, or even yourself?

This is one of the most common complaints that I hear in my medical practice. It seems, these days, that everybody is suffering from some degree of fatigue. What is happening?

Why are we all so tired all of the time?

It is possible, if you are reading this blog, that your energy is out of balance. Out-of-balance energy manifests in a number of ways:

  • Fatigue
  • Poor thinking
  • Brain fog
  • Low motivation
  • Anxiety
  • Low libido
  • Weight gain

Take a trip back in time to see what drives human energy balance.

To really understand how energy balance plays into the clinical complaint of “fatigue”, we need to step out of our roles as “modern” humans. To best understand, and then treat energy-related illnesses, we need to reexamine ourselves within a new light.

Actually, we need to examine ourselves within an old light. This is the light of our ancestry. Our physiology was designed long before our faces were lit with fluorescent bulbs, computer monitors and smartphone screens.

Our current stressors may be modifying our genetics negatively. Which of the following have you been exposed to in just the last few hours? What about in the past week?

  • Stress
  • Noise
  • Artificial light
  • Artificial or processed food
  • Chemicals of all kinds

The “light” that illuminates our lives in the year 2018 is far different from the light our distant ancestors saw.

The earliest human, a petrified skeleton known as “Lucy”, is felt to be more than three million years old. The Industrial Age, with the onset of pollution, synthetic chemicals, and related environmental exposures, has lasted less that 150 years. Let’s do some simple math.

Total time (plus or minus) of humans on the planet: 3 million years
Total time with “modern” stressors: 150 years

Percentage of time that our genetics have been exposed to the boxed list above:

150 years/2.5 million years= .005% of our time on Earth.

That’s right, our genetics are being battered by a slew of new exposures for a period of time that represents only .005% of our time on this Earth.

Is it possible that our genetics are not equipped to deal with the changing environment to which we are exposed? I think that the answer is “yes.”

So why are we so tired all of the time?

Let’s look at a “day in the life” of one of our pre-modern ancestors.

A day in the life: Why a caveman or cavewoman felt fatigue

The sun comes up. The sounds of a bird’s morning call echoes in your cave. You crawl out from under the bearskin rug, blink, and stretch your arms. You are pretty hungry. It has been a while since you last ate.  You need nutrition.

So you head to the fridge to grab some leftover pasta and a Coke. Maybe pop a Hershey’s Kiss into your mouth as you pass through the den.

No, wait. Wrong epoch.

We need to go much further back in time.

We need to consider the time when there were no refrigerators, no pasta, and no chocolates. In this time, there were no stores, no packages, and no guarantee that you would have breakfast. Or lunch. Or dinner. Or anything.

You scurry over to a rock in the back of the cave and turn it over to see if there are any more remaining nuts and seeds from your collection the previous week. But again the squirrels swiped them while you slept. You take a big sigh. You are hungry.

Your stomach growls. It has been days since you have felt a full belly, and your biology begins to feel the stress of not eating.

The need for calories is generating a stress response. Our survival depends on this stress.

Every living organism on the planet has stressors, and needs to be able to respond to stress to survive.

Why a stressed body is a fatigued body

We have been exposed to a lack of, rather than an excess of food, for the majority of time that we have been on this planet.

Our biology is wired to respond to longer periods of caloric poverty, punctuated with shorter intervals of caloric wealth.

Caloric restriction is a stressor to the human body, whether we are living in caves or condos. When we are not able to maintain our blood sugar by continually putting food into our mouths, we need to harvest that energy from somewhere else to simply stay alive.

We have systems in place to do this. The energetic triad of, cortisol, insulin and thyroid hormone, keeps us alive by maintaining energy to our heart and brains.

Within this triad, we find one of the greatest clues for management of fatigue.

Cortisol: The adrenal hormone that will either save your life or kill you.

Let’s face it. Being hungry is a drag. Have you ever been so hungry that food is about the only thing that you can think about? We all have. Here our survival instincts gear up, and rightfully so.

Hunger, a response to inadequate caloric intake, is our primary stressor as a human. While we may think that the crying child or pinging cell phone is stressful, our physiology knows otherwise. If we don’t maintain a steady supply of energy to our hearts and brains, these other factors become mere commentary.

Our cells don’t think: they respond. And they respond primarily to the hormone cortisol.

Cortisol is the master planner.

Cortisol is the King of the body’s castle.

All of our body’s hormones and functions defer to the messages that cortisol sends. Because if we can’t respond to the stress of a long fast, we won’t make it.

Or if we fail to respond to the stress of an illness, we will weaken and die.

Or we lack the energy to get up and move, we might become tiger food.

Messages from the brain instruct the adrenal gland to release the hormone cortisol. These messages are so important that they travel both through the nerves and the bloodstream.

The adrenals get a direct message through the nerves of the sympathetic nervous system. This is the brain’s bullet train to activate the “fight or flight” response.

The adrenals additionally receive a hormonal signal from the brain delivered through the blood. This messaging is a bit slower than through the nerves, but with the same response. The hormone cortisol profoundly influences our body’s survival biology.

Cortisol, is the King of hormones, I’ll say it again.


  • Raises our blood sugar, blood pressure, heart rate. Cortisol, along with adrenaline, get us ready for a fight.
  • Directs the production, or suppression, of our sex hormones.
  • Shunts blood away from our gut. The gut siphons off some 20% of our heart’s output. Being chased by a tiger? Our body sets priorities. Survival mode says that it’s better to have the blood and oxygen in the muscles and lungs. We can digest the sandwich later.
  • Suppresses our immune system. Do you fight a tiger, or fight a cold?

Cortisol melts down the body. It tells the body to trade muscles for survival; immunity for escape; digestion for defense.

Insulin: Prehistoric savior, modern-day foe

We just saw how cortisol’s job is to raise the blood sugar, allowing us to survive a stressor, fast or fight. It does this, however, at great cost. Recovering from a prolonged fast, recurrent infections, or constantly battling a tiger (real or imagined) robs us of energy.

Thyroid hormone and insulin form the remaining two legs of the energy “stool” that keep our energy needs balanced. We will see how these three systems are related to one another, and why they are crucial to address your fatigue.

Let’s reconsider our cave dweller. She leaves her cave, and has one of two options. She will find food, or she won’t. As hunter-gatherers, we never had lots of food for long periods of time.

But today, she stumbles onto a tree laden with ripe mangoes. She begins to eat. What happens?

As the food is digested, and the sugars enter the bloodstream, the pancreas springs into action. The hormone insulin is released. Insulin is a growth hormone, and anabolic. This means that it causes tissues to grow.

The hormone insulin:

  • Promotes uptake of glucose into the muscles and liver. Here it is converted to the molecule glycogen. Glycogen is a storage molecule, which is readily broken back down to free glucose when we need that energetic burst.
  • Inhibits the production of glucose via gluconeogenesis. The name says it all. Gluco(glucose)-neo(new)-genesis (origin) takes our fats and proteins, and converts them back to glucose. In times of adequate caloric intake, we no longer need to keep our brain and heart alive by utilizing the calories we have stored in our proteins and fats. We are taking in glucose at regular intervals. Delicious mangoes!  We don’t need to break down our tissues to stay alive, and don’t need to make a withdrawal from our energy bank.

Simply speaking, insulin:

  • Lowers blood sugar
  • Stores glucose as glycogen
  • Is a growth hormone. It makes tissues bigger and stronger

In later posts we will see how excessive insulin is a problem. With the unending calories found in modern life, continued insulin production leads to pancreatic “burn-out.”  Over time we see too much growth (obesity), loss of insulin function (diabetes), and the well-known medical conditions that accompany these diagnoses.

But that wasn’t a concern to our prehistoric genetics. Here insulin was more closely tied to survival. The human body wasn’t designed to be exposed to too much food. Our more pressing concern has always been finding enough calories to simply stay alive. When we had the opportunity to take in calories and store them, we did so vigorously.

The next period of starvation was always just around the corner. Insulin builds tissues and stores energy while the “gettin’ is good.”

Thyroid hormone: Our thermostat for survival, our barometer for fatigue

Now let’s assume that our cavewoman didn’t find a nice plump mango that morning, that day, or even that week. In fact, a late summer drought and long winter has left her on the brink of starvation. She is really struggling.

Hopefully the past year she packed on enough meat on her bones to make it to the Springtime, when the bunnies, birds and berries would surely reappear. But for now, it is a true fight for survival.

We already know the first two-thirds of the stress response.

First, her cortisol rises. This primary stress hormone helps to maintain her blood sugar levels, keeping her brain and heart alive.

Second, insulin is suppressed. When blood sugar is low, she doesn’t want to produce another hormone that makes it even lower.

Thyroid hormone is the third leg of the stress-response stool. The thyroid gland is the body’s thermostat. When we are under stress, we turn down our metabolism.

A lowered metabolism makes sense. If we have managed to store a finite number of calories on our bones, we don’t want to burn through them when times are scarce. We can survive a long winter with a lower body temperature, cold hands and feet, dry skin. Ongoing stressors slow the body down.

Our muscles, brain, gut– they all seem to drag. Our thinking is less clear, and we just start shutting down. And the act of reproduction, which requires our sex hormones? Don’t even think about it . We can engage in those activities when we have excess energy. Maybe the “not tonight, Dear” is a product of biology, not of desire.

Go back to the top of the page, and look at the symptom list that we started with. A fatigued patient may display all of these symptoms. And all of them would be expected if we were under a persistent state of stress.

What about weight gain? In our modern world, we have plenty of calories around at all times. Unlike our ancestors, as the fatigue builds up, so too does the weight.

Why is this? To answer, we just need to go back to the normal physiology.

Why weight gain and fatigue are explained by normal physiology

Cortisol goes up in times of stress. To our cavewoman, the primary stressor was not having enough to eat. She didn’t worry herself with traffic, an overbearing job, or her cell phone battery dying. Chemicals and toxins didn’t burden her physiology.

Starvation is rarely a real risk factor in our modern society. Calories are everywhere.

So is stress.

Stress causes the release of the hormone cortisol, which readies us for a challenge. And don’t forget that cortisol is King.

The cells that respond to cortisol’s message, don’t question “why?” They don’t question the King. They just respond with predictable physiologic changes.

  • Cortisol suppresses our thyroid gland function. In a hypothyroid state, our physiology and metabolism all slow significantly. This is a valuable adaptation if there isn’t enough food around. If you are running your car on fumes, hoping to make it to the next gas station, you don’t sit at the stoplights revving the engine. The body functions the same way.
  • Our insulin functions less well. With poor insulin signaling, we don’t store glycogen in the muscles and liver. The glucose in our blood is converted to a molecule known as a free fatty acid. Fat cells greedily take up these fats. We get fatter with suppressed insulin function, and higher insulin levels.
  • Our gut functions less well. We develop constipation, and a slowed transit time of food through our intestines. This increases the absorption, and decreases the elimination of toxins. With decreased blood flow to the gut, we develop lowered immunity, and imbalances in the microbial inhabitants.

A vicious cycle ensues. We foster lowered thyroid function and decreased metabolism. This leads to poor insulin signaling with deposition of free fatty acids in our greedy, uncooperative fat cells.  Altered gut function promotes lowered immunity, impaired digestion and absorption of our food, and poor elimination and detoxification.

In a nutshell, we get tired, fatter, and have less energy to do the things that bring us a sense of fulfillment in life. All of this occurs in response to “normal” physiological changes.

Balance your energy, balance your life

The three hormones thyroid, insulin and cortisol are designed to work in concert to keep us alive. They are also crucial for sex and reproduction, but these activities are all secondary to just staying alive when cortisol is driving the bus.

To beat fatigue, and get back into the sunshine of life, we must examine these three systems collectively. Understanding of, measurement and management of the energetics hormones is a crucial first step in your journey to get better.

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