If you are looking to build muscle or lose fat, but struggle to do so due to a hectic lifestyle, then your cortisol (the stress hormone) levels might be too high. This hormone can be a silent killer in the 21st century — so why do we produce it if it’s bad for us.

Well, not everything is as it seems.


In a pre-industrial society, cortisol is actually a good thing. It puts you in survival mode, helping you survive for longer by regulating your metabolism, during times of uncertainty and great upheaval.

Cortisol may be a catabolic hormone, but this is for good reason, as we shall explain below.

What is Cortisol and How is it Produced?

Cortisol is a glutocorticoid steroid hormone that is produced in the adrenal glands as a response to being in a sustained fight or flight mode. The adrenal glands are triggered by the pituitary glands after recognizing a perceived threat.

Now, cortisol itself isn’t a bad thing in a state of nature, it has the following functions [R]:

  • allows the body to respond to stress or danger
  • increases the body’s metabolism of glucose
  • controls blood pressure
  • reduces acute inflammation, increases markers for chronic inflammation
  • regulating metabolism/energy preservation
  • it renders the body more insulin resistant

In pre-industrial times, cortisol would be released during war, famine, drought, etc., where resources are scarce to preserve energy stores — fat — at the expense of the more metabolically active/expensive muscle. Fat, although dangerous in excess, is a far superior (2.25x) energy store to muscle, and muscle requires more calories to maintain. An abundance of muscle mass — being metabolically expensive — can be shed when cortisol levels are elevated.

Inhibitory control failures and blunted cortisol response to psychosocial  stress in amphetamine consumers after 6 months of abstinence. - Abstract -  Europe PMC

However, in a modern setting, you can be simultaneously stressed and showered with calorie dense food.

Think about the average worker in a cubicle working to hit tight deadlines: cortisol is released as there is a perceived threat, but there is no food scarcity. That stressed worker’s basal metabolic rate will have slowed down, while potentially comfort eating.

You are put in a situation where you are prone to fat gain, muscle wastage, high blood sugar, and blood pressure, while facing extra temptation to consume foods/products that invariably exacerbate the aforementioned conditions.

Is It Catabolic?

The stress hormone is absolutely catabolic.

On the one hand, it renders you more insulin resistant, and, on the other, it can utilize muscle tissue as energy to preserve fat store.

Moreover, being in this state can damage your sleep quality which will both ruin your post-workout recovery and workout quality down the line.

To compensate for a lack of sleep, you may enter a vicious cycle of stimulant/caffeine use to help you through difficult times, while they simultaneously add fuel to the proverbial fire and lower your quality of sleep.

Inflammation — acute inflammation — is needed in conjunction with insulin sensitivity to repair damaged cells after training to facilitate the process of recovery. Chronic stress decreases both inflammation and insulin sensitivity, hampering your ability to repair your muscles after training stimulus.

Cortisol and Sleep Deprivation

Stress and Stress Relief | The Village Family Service Center

Cortisol and sleep deprivation go hand in hand.

Moreover, sleep deprivation dysregulates ghrelin and leptin — your hunger hormones — signaling more hunger and less being full, leaving you more prone to overeating. Researchers have also found that sleep deprivation increases the chances of you craving foods that are higher in carbohydrates and more calorie-dense.

Couple this with the metabolism-slowing effects of cortisol and you have a recipe for crash weight gain — and not of the good kind, either.

Check out our article on how you can boost your metabolism to accelerate fat loss.

The hypothalamic-pituitary-adrenal (HPA) interacts with sleep quality in several ways [R].

According to Natural Medicine Journal:

“Depression and other stress-related disorders are also associated with sleep disturbances, elevated cortisol,11 altered NE levels,12 and HPA axis dysfunction.13 Interestingly, chronic insomnia without depression occurs with elevated cortisol levels, particularly in the evening and the first part of the nighttime sleep period.14-17

“This elevation in cortisol may be a primary cause of the sleep disturbance. In addition, the elevated cortisol may be a marker for increased CRH activity and CNS norepinephrine.18-20 In summary, HPA axis hyperactivity can have a negative impact on sleep, leading to sleep fragmentation, decreased deep slow-wave sleep, and shortened sleep time. In turn, sleep problems including insomnia and obstructive sleep apnea can further propagate HPA axis dysfunction.”


A prolonged low-calorie diet has been clinically proven increase cortisol levels. This, in turn, increases the likelihood of choosing poor quality foods to satisfy hunger pangs or to quell bouts of stress.

A study found [R]:

“In a 2 (monitoring vs. not) × 2 (restricting vs. not) fully crossed, controlled experiment, 121 female participants were randomly assigned to one of four dietary interventions for three weeks. The monitoring + restricting condition tracked their caloric intake and restricted their caloric intake (1200 kcal/day); the monitoring only condition tracked their caloric intake but ate normally; the restricting only condition was provided 1200 kcal/day of food but did not track their calories, and the control group ate normally and did not track their intake. Before and after the interventions, participants completed measures of perceived stress and two days of diurnal saliva sampling to test for cortisol.”

Concluding that:

“Dieting may be deleterious to psychological well-being and biological functioning, and changes in clinical recommendations may be in order.”

However, the effects of obesity or excessive bodyfat outweigh any temporary psychological distress that may be experienced through dieting.

Dieting doesn’t necessarily have to be equated with suffering; we recommend a daily caloric deficit of 500-600 calories per day.

Cortisol, Fat Gain, and Insulin

insulin resistance

As we’ve mentioned, cortisol taps into protein stores — muscle — to keep blood sugar levels elevated through a process called gluconeogenesis that occurs in the liver.

Elevated levels can lead to elevated blood sugar levels and increase the risk of Type 2 Diabetes.

High blood sugar levels alongside insulin suppression can leave cells requiring extra energy, thus increasing hunger.

Studies have shown that cortisol levels directly correlate with increased hunger [R].

Today’s Dietitian also stated:

Repeated elevation of cortisol can lead to weight gain.2 One way is via visceral fat storage. Cortisol can mobilize triglycerides from storage and relocate them to visceral fat cells (those under the muscle, deep in the abdomen). Cortisol also aids adipocytes’ development into mature fat cells. The biochemical process at the cellular level has to do with enzyme control (11-hydroxysteroid dehydrogenase), which converts cortisone to cortisol in adipose tissue. More of these enzymes in the visceral fat cells may mean greater amounts of cortisol produced at the tissue level, adding insult to injury (since the adrenals are already pumping out cortisol). Also, visceral fat cells have more cortisol receptors than subcutaneous fat.

Testosterone and Fertility

And if all the above isn’t bad enough, elevated cortisol levels can suppress your testosterone levels.

“That may be true, but there is an old saw in research that you need to remember,” says Daniel Shoskes, MD, a urologist at the Cleveland Clinic. “Association does not equal causality. There is very little evidence that stress lowers testosterone and even less evidence that lowering stress will raise testosterone. That being said, we do know that acute and chronic stress have physiologic effects on the body. So, lowering stress could help with low testosterone symptoms like low libido, low energy, and depression.”

Testosterone might also play an important role in improving immune health, to add insult to injury.

Given the drop in sex hormones for both men and women, it is believed that cortisol can directly impact fertility levels [R].

Immune Health and Aging

Although cortisol is anti-inflammatory, reducing acute inflammation, studies have shown that chronic elevated stress levels increases cytokine production — a marker for chronic inflammation [R].

This suppresses immune response in addition to insulin suppression.

Furthermore, according to a research paper, “an important direction in aging research involves an examination of telomeres. Telomere length has been used as a measure of biological aging and is associated with psychological, physiological, and social factors. Chronic stress is linked to shortened telomere length along with increased disease in older adults [22].”

Cortisol and Stimulants

Stimulants such as caffeine and amphetamines can increase stress levels.

Caffeine, in smaller doses, can elevate mood, but in excess can spike cortisol levels and impair sleep quality.

Below, is a chart measuring cortisol levels and MDMA (ecstasy use).

Cortisol and testosterone levels for 12 recreational ecstasy/ MDMA... |  Download Scientific Diagram

What Can Be Done


Eliminating stress must become a top priority when attempting to lose fat or gaining muscle.

Aside from going directly to the source and targeting cortisol through blockers or supplementation, we recommend lifestyle changes to eliminate individuals, work requirements, or living situations that may be the source to this silent killer.

Do some of the following:

  • Cut toxic people from your life
  • Spend more time outdoors
  • Spend less time on your computer/TV
  • Lift Heavy Weights
  • Lose Fat
  • Eat Whole Foods
  • Walk
  • Meditate
  • Get more sleep
  • Change jobs
  • Wean yourself off stimulants

If you’d like to go through another route, you can supplement the following:

At Herculean Strength, we recommend going through more conventional routes that involve the least amount of supplementation possible.

Don’t hesitate to email us at [email protected] for personalized coaching and a client questionnaire if you’d like DEDICATED tailor-made personal training on strength training, building muscle, losing fat, developing athleticism, and more — all to your liking, lifestyle, habits, and taste!

Otherwise, don’t forget to claim your FREE eBook detailing how to lose 20lb of fat while building muscle in 12 weeks! You can claim it here.

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