What is Cortisol? Debunking the Myths.


What is Cortisol? Debunking the Myths.

Stress and Cortisol

I’m going to point out two terms here – stress and cortisol. Now, technically (from a biological perspective) they are two different things. But for the purpose of this article, I am using them interchangeably.

Firstly, you need to understand what cortisol actually is. Cortisol (C21H30O5) is a steroid hormone within the glucocorticoid family and is produced in the adrenal gland in humans. It is our body’s main stress hormone triggering our fight or flight mechanisms. Levels in the body are controlled in multiple feedback loops within the hypothalamic pituitary adrenal (HPA) endocrine axis. The hypothalamus senses if we have too low cortisol and releases corticotrophin releasing hormone (CRH) which subsequently sends a signal to the pituitary gland to releases adreno-corticotrophin (ACTH) and stimulating the adrenal cortex to produce cortisol. When levels get too high, this signalling pathway is stopped so no cortisol is released – until levels fall back to “too low” and the signals start again.

Sensitive mechanisms control these loops which adjust the circulation of cortisol in everyday life. Typically physiologically actions of stress-induced rises in cortisol happen after an hour after the HPA axis has been simulated. Cortisol has a half-life of around 70 minutes, so continual stress signals can wreak havoc on this delicate system. Both environmental and endogenous (within body) stimuli act in conjunction to control non-cellular mechanisms around cortisol release through the HPA axis.

The HPA Axis

What Does Cortisol Do?

Without cortisol, our body wouldn’t function. So do not see cortisol as a bad hormone. Cortisol plays a key role in the metabolism of proteins and fats and in gluconeogenesis (conversion of carbohydrates to ATP for energy).

Cortisol enhances our immune response – decreases circulating leukocytes and increasing them at sites of injury in a process called “stress-induced trafficking”. Similar to the way that vascular shunting works. A sudden peak in cortisol (through stimulation of ADRB2 gene (beta-2 adrenergic receptor)) gives us the flight or flight response – our natural and healthy response to threats. If we do not have enough cortisol to “stress” our body, then this process becomes inhibited and you are likely to get eaten by a lion.


What Happens If Levels Go Awry?

It is well known that an increase in cortisol (above normal levels) is associated with increases in blood pressure and an alteration in metabolism that results in obesity, insulin resistance and changes in lipid metabolism. In women, high levels of cortisol correspond to a typical adrenergic pattern of fat distribution – that is fat around the waist especially in those women with PCOS.

Why? Well you need to know some nerdy science. Glucocorticoids augment the action of our catecholamines and other vasomodulators on the cardiovascular system that also support the mobilisation of glucose and lipids. Epinephrine (one of these catecholamines / neurotransmitters) in the brain, acts quickly to increase blood glucose levels, whereas cortisol acts more slowly and maintains higher blood glucose for longer, in part, by increasing insulin resistance. Elevated cortisol for too long leads to insulin resistance and hence fatty acids are no longer mobilised and instead get stored.

High cortisol levels wreak havoc on a women’s libido and menstrual cycle, which may in part be down to its effects on metabolism and therefore the HPTA axis. The effects on hormones here for women see a general androgenic adiposity displacement (fat around the middle), facial hair and irregular menstrual periods. Low energy availability (low energy intake) causes more pronounced changes in thyroid, insulin and cortisol in women, especially at low body fat! But hormones and cortisol are another post completely.

But what about if levels are too low? In order for our bodies to respond, adapt and react to different situations, it’s good for them to have something “bad” happen. You get a cold, you develop an immune response, and then next time you get the cold you are able to better deal with it. This is called adaptive immunity. You are in the gym, training to get bigger and stronger. The only way to build muscle is to break them. You cause micro-tears that the body heals by patching up the gap with more muscle, and hence making them bigger and stronger. Well, the more stress that our body faces, the better we are able to deal with it in the long run. A dysfunctional HPA axis is associated with low cortisol production and this can lead to increased disease risk, especially if this leads to non-suppression of other stress responses such as allergies, immune disorders or inflammation – all of which cortisol help to protect us from.

When cortisol is chronically elevated, its effects become distinctly negative. It causes protein to break down (and if there is no recovery period, the tissues don’t get a chance to repair themselves). Bone production is inhibited which can cause a loss in bone mineral density. Memory, immunity, reproductive function and sex drive all become impaired when cortisol is out of control. This is the same for insulin and leptin which both become resistant and therefore give rise to negative effects on body weight and fat regulation. Hello beer belly.


Supplements to Control Cortisol

If you have identified that you are constantly in a high cortisol environment, supplement can assist the lifestyle changes you make. We would suggest an adaptogen, such as ashwagandha, to improve the body's response to stress.

If stress is causing a negative feedback loop in your fat loss phase (high stress because of dieting leads to impaired progress leading to more stress) we have specific fat burning supplements to address this mechanism, such as Lean Xtreme or Reduce XT.

PES Omnizen

Take Homes

Quick note: Now remember, cortisol is a physical stress, not a psychological one. Psychological stress is a completely different topic (although related to cortisol as well), but this is situational and personal so it becomes much more complicated.

We are constantly told that cortisol and stress is a bad thing. Well, no it isn’t. It is important to understand that cortisol levels vary in everyday life – and this is normal. Our cortisol is highest in the morning upon waking and then naturally reduces throughout the day.

Cortisol rises during exercise! This is causing an adaptive response. So, when you finish your session, don’t start popping pills to lower your cortisol. You are effectively inhibiting your gains by doing this.

If you feel you are a particularly stressed person, or you have an important day ahead that you need to be a little more relaxed for, then using some cortisol lowering supplements in the morning with your breakfast is the best time. If our cortisol is too high, this causes an effect similar to too much caffeine – anxiety, jitters and that wired feeling in your brain. Important exam? Important meeting? Lower your cortisol before you to help relax a little more.

“Short term rises in cortisol are needed for adaptation of rebuilding and repairing. Long term high levels of cortisol stops this process and eventually causes aspects of the body to break down. “



By Lucy Ellis. Lucy is a qualified nutritionist having obtained two degrees in human and sports nutrition. She is currently studying her PhD in functional foods and neuro degeneration whilst pursuing her passion of bodybuilding and food. Find her on Instagram @LucyEllis_Fitness

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