Over the past few weeks there has been a rise in posts about somatic exercise and how the release of stored stress and trauma in the body can lead to weight loss. It was really difficult to write an Instagram post about it, as there’s so much nuance to cover about stress and the human body. I also saw an article by a Dr that was titled ‘weight loss remains a dream unless we manage cortisol’.
From throwing myself head first into pubmed to investigate this further, I can see why people have latched onto the science in this way. But first, it is important to have some background understanding about cortisol before we start asking if we can regulate it or if it’s the key to weight loss.
In this deepdive, I have attempted to answer the following questions:
What is cortisol? What is Stress? What is Allostatic load? What is the diurnal cortisol slope? How does cortisol impact our mental and physical health? What don’t we know about cortisol? And should we care?
There are a few reasons why researchers have been looking into cortisol.
Firstly, cortisol is responsive to social and psychological stress, both acute (short term - someone calling you a wanker in the street) and chronic (long term - someone repeatedly calling you a wanker in the street). Second, the HPA axis (we will get to know more about this in a minute) is influenced by developmental experiences, so, things that happen to you when you’re young like being bullied, abuse, being in foster care etc. Thirdly, cortisol is thought to play important roles in daily cognitive and behavioural functioning - so not the pure devil it’s been made out to be and, fourth, it has been linked to a wide range of physical and mental health outcomes.
What is cortisol?
Though widely known as the body’s stress hormone, Cortisol has a variety of effects on different functions throughout the body.
The hypothalamus-pituitary-adrenal (HPA) axis regulates both production and secretion of cortisol. Loss of regulation can lead to cortisol excess disorders, such as Cushing syndrome, or cortical insufficiency, such as Addison disease.
HPA axis sounds REALLY complicated but all this does is describe the relationship between parts of your body that aid in the secretion cortisol.
Your hypothalamus is a structure set deep within your brain, it’s main function is to maintain homeostasis. Homeostasis is good because it means you’re not terribly ill, dying or dead. It directly influences your automatic nervous system and it manages your hormones.
Your pituitary gland - the ball sack of the brain - is a small gland found in your brain. Despite being small, this gland is the ‘master gland’ and tells every other gland what to do.
The hypothalamus releases some stuff which tells the master ball sack to send a message to the adrenal gland.
That, in a nut shell, is the HPA - axis.
Cortisol has many functions in the human body, such as mediating the stress response, regulating metabolism, the inflammatory response, and immune function, plus it is able to affect nearly every organ system.
After waking, cortisol peaks in the body (more on this later) and this is thought to play an important role in synchronising the body in both the sleep wake and light dark cycles - commonly known as circadian rhythm.