Exercise and the stress hormone cortisol

The following article was written by Skip Franzsen, South Africa and appeared on this website on 13 Dec 2015.

Questions about weight loss plateaus and exercise are often asked by eager Banters. We live in an age when access to a gym is common. Modern life is filled with high levels of daily stress. Some of us live with constant work-related stress. Some people may actually increase their levels of stress via a significant change in their diet. Like many other people new to Banting, when I started LCHF I assummed that I could double my rate of weight loss by increasing the amount of exercise I did. And when that didn’t work, I figured I needed to increase my rate of exercise again and again. It has got to work sometime right? Wrong. You may be creating hormonal imbalances that stops weight loss in its tracks.

As I lost weight via Banting earlier this year (read full story here), I started to walk. At first, even a gentle stroll left me breathless, but it soon became a hard ‘cardio vascular workout’. I walked twice a day, five or six days a week, covering 200 kms in 9 weeks. My body got fitter but my weight plateaued. When I asked why I was not losing weight, I was told that the increased exercise was adding muscle and this weighs heavier than fat; therefore, no weight loss. I think there is some logic to this as clearly my body muscles and overall shape did change, yet I still lost little weight despite all the extra effort.

So I started reading and found this reference to be very helpful; and it needs to be shared. Christine Cronau, an Australian dietitian and author discusses over-exercising in her book The Fat Revolution (Cronau, 2012, p. 106), saying:

‘Conventional wisdom would certainly like to convince us that frequent exercise helps with weight loss, but there are some very good reasons why exercising too much will actually force our body to retain weight.

If someone asks me why they aren’t losing weight, around half the time, they are exercising five or six days a week. Over-exercising, particularly vigorous cardiovascular exercise, causes our cortisol (stress hormone) level to rise, and the body responds by stopping all forms of energy storage, meaning it will no longer store glycogen in our muscles for energy. When glycogen can’t be stored, it is converted to fat and stored in our fat cells. If we only produce cortisol occasionally, it isn’t an issue, but if we are producing excess cortisol by exercising often and vigorously, it certainly is a problem. Elevated cortisol levels cause our body to lose muscle and store fat, reduce our metabolism, and increase our appetite’.


Now that we know that our stress hormone, cortisol, can make us hang on to fat, imagine what happens when we live in a state of high stress. We get fatter. And think about the stress we experience when we continually jump on the scales, only to find that we’ve gained weight!

‘To maintain our health and our weight, it is important to take a step back and reduce our stress levels. Slowing things down doesn’t mean we get less done; in fact, we are more likely to achieve more in a calm, centered state’ (Cronau, 2012, 106).

It is well-known that the human body has an evolutionary response to stress called the “fight or flight” response. The pituitary gland in the human brain produces the hormone adrenaline which has an immediate short-term effect, heightening the body’s response to a stress event. It immediately gives the body increased power and strength.

Just one of the outcomes of the release of adrenaline is that it supports the release of the long-lasting and potent stress hormone called cortisol from the adrenal glands. Cortisol, in effect, protects the body from extreme stress and just one of the ways it does this is to lock down those parts that increase weight loss. It can actually drive weight gain. I found the effect of cortisol reduces in a day or so of moderate exercise.

But as the human body is extremely complex, the question of how to balance these hormone becomes much more complex. Hormonal balance is really a complex reaction between four different hormones that may be stopping your weight loss, and indeed may be playing havoc with your overall health and coping mechanisms. An important goal is to keep these hormones in natural balance. For an in-depth understanding of this topic, I recommend the article ‘It’s not you: it’s your adrenals’ by Dr Sara Gottfried (no date), who is a specialist in the field. Another excellent article is called called ‘Are these four hormones blocking your weight loss efforts?’ by Dr Steven Sisskind (no date).

Fitness coach Vanessa Bennington will assist you in understanding the implications related to weight loss and exercise in her article ‘The ups and downs of cortisol: what you need to know’ (Bennington, no date). Describing her own journey to fitness and health, she says:

‘A lifetime of improper nutrition and eating disorders had created hormonal and metabolic chaos. It wasn’t that she had spent almost two decades doing things wrong or not trying hard enough, it was that she had never tackled the entirety of the issues. Adjustments to her exercise, nutrition, medication and supplementation brought balance to her hormones and lifted the crippling depression and anxiety. She had the quality of life she always dreamed of, physical strength she never knew she was capable of, and the body she had worked a lifetime for started to show the results of her efforts’ (Bennington, no date).


So really, what is it all about? In simple terms, to Bant effectively you need to keep your insulin levels low on a sustained basis by reducing your carbohydrate levels to under 25g per day. And if you exercise, you need to also exercise in such a way that your cortisol levels are kept under control. Banting is about low carb intake but also about moderate exercise. If weight-loss is your major goal, make sure you exercise in a way that controls your stress hormone cortisol. This may require you to do less exercise or to exercise less often.


Bennington, Vanessa (no date). ‘The ups and downs of cortisol: what you need to know’, article posted on website Breakingmuscle.comhttp://breakingmuscle.com/health-medicine/the-ups-and-downs-of-cortisol-what-you-need-to-know, last accessed 12 Dec 2015.

Bergland, Christopher (22 Jan 2013), ‘Cortisol: Why ‘The Stress Hormone’ is public enemy no. 1’, article posted on website Psychology Todayhttps://www.psychologytoday.com/blog/the-athletes-way/201301/cortisol-why-the-stress-hormone-is-public-enemy-no-1, last accessed 12 Dec 2015.

Cronau, Christene (2012). The Fat Revolution, Purple Lotus Publishing, Australia.

Gottfried, Sara (no date). ‘It’s not you: it’s your adrenals’ on the website Dr Sara Gottfried MDhttp://www.saragottfriedmd.com/its-not-you-its-your-adrenals/, last accessed 12 Dec 2015.

Sisskind, Steven (no date). ‘Are these four hormones blocking your weight loss efforts?’ article posted on website Dr Sara Gottfried MDhttp://www.saragottfriedmd.com/are-these-four-hormones-blocking-your-weight-loss-efforts/, last accessed 12 Dec 2015.

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