While healthy lifestyle education and access to nutritious food are important factors in the prevention of overweight and obesity, an easily overlooked piece of the obesity puzzle is uncontrolled, chronic stress. Unmitigated, ongoing stress caused by the pressures of daily life (e.g., relationship issues, financial problems, work-related stress) especially when combined with long working hours and poor sleep, can result in chronically high cortisol levels. Cortisol, a glucocorticoid (GC) hormone produced by the adrenal glands as part of the stress response, is known to increase the appetite for energy-dense foods rich in fat and sugar and cause a redistribution of fat to the abdominal region.1 This is because fat- and sugar-filled foods appear to have an effect that suppresses stress-related responses and emotions.2 In addition to junk food cravings, excess cortisol can lead to sleep deprivation and even alcohol use in some people, both of which have been shown to dysregulate the body’s cortisol levels even further.3–5 This cycle creates a perfect storm for weight gain.

Recent advancements have changed the ways that scientists are able to measure cortisol levels in humans, opening up opportunities for new insights into how cortisol affects our bodies in the context of chronic stress. Researchers have started using hair strands to measure chronic cortisol levels in humans, termed hair cortisol concentration, as opposed to using blood, saliva, or urine, which only show cortisol levels at the time samples are taken.6 Using hair cortisol concentration, research has shown that people experiencing chronic stress display hair cortisol concentrations 43 percent higher than normal controls,6 and individuals with obesity have, on average, higher levels of long-term cortisol.1 Another study evaluated long-term cortisol levels of 3,000 children and found that those children with the highest long-term cortisol levels were 10 times more likely to have obesity.7

Cushing’s syndrome, or hypercortisolism, is an example of the relationship that high cortisol levels have with obesity. Cushing’s syndrome develops when your body produces too much cortisol on its own or as a result of oral corticosteroid medication. Symptoms of Cushing’s syndrome include progressive weight gain and fatty tissue deposits, particularly around the midsection and upper back, in the face (moon face), and between the shoulders (buffalo hump); pink or purple stretch marks on the skin of the abdomen, thighs, breasts and arms; thinning, fragile skin that bruises easily; slow healing of cuts, insect bites, and infections; and acne.8

While a strong relationship between obesity and long-term elevated cortisol levels exists, not all people dealing with excess weight will show excess cortisol levels. This is believed to be partially due to genetic factors that determine glucocorticoid sensitivity.8

“Calories in, calories out,” is a common phrase in the world of weight loss. It sounds simple, but it is true—eating fewer calories than you burn should lead to weight loss, and eating the same number of calories you burn should prevent weight gain. However, when considering the relationship between stress, cortisol, and obesity, it’s clear that there are other factors beyond how much we eat and exercise that can affect our ability to maintain a healthy weight. Unchecked stress levels can alter our body chemistry in unhealthy ways, and this underlines the importance of using strategies to control stress levels for better overall health.

SOURCES

1. Spencer SJ, Tilbrook A. The glucocorticoid contribution to obesity. Stress. 2011 May;14(3):233–246.

2. Harvard Health Publishing site. Why stress causes people to overeat. Updated: 18 Jul 2018; Published: Feb 2012. Harvard Mental Health Letter. https://www.health.harvard.edu/staying-healthy/why-stress-causes- people-to-overeat. 10 Dec 2018.

3. Martens MJ, Rutters F, Lemmens SG, et al. Effects of single macronutrients on serum cortisol concentrations in normal weight men. Physiol Behav. 2010 Dec 2;101(5):563–567.

4. Blaine SK, Sinha R. Alcohol, stress, and glucocorticoids: From risk to dependence and relapse in alcohol use disorders. Neuropharmacology. 2017 Aug 1;122:136–147.

5. Minkel J, Moreta M, Muto J, et al. Sleep deprivation potentiates HPA axis stress reactivity in healthy adults. Health Psychol. 2014 Nov;33(11):1430–1444.

6. Stalder T, Steudte-Schmiedgen S, Alexander N, et al. Stress-related and basic determinants of hair cortisol in humans: A meta-analysis. Psychoneuroendocrinology. 2017 Mar;77:261–274.

7. Noppe G, van den Akker EL, de Rijke YB. Long-term glucocorticoid concentrations as a risk factor for childhood obesity and adverse body- fat distribution. Int J Obes (Lond). 2016 Oct;40(10):1503–1509.

8. van der Valk ES, Savas M, van Rossum EFC. Stress and obesity: are there more susceptible individuals? Curr Obes Rep. 2018;7(2):193–203. NHR