obert Sapolsky, in his book originally published in 1994, entitled “Why Zebra’s Don’t Get Ulcers”, discusses the negative impact chronic stress has on metabolism and overall health. The basis for the title of his book is as follows: zebra’s don’t get ulcers because zebra’s are not subject to chronic stress and chronic stress is one of the strongest modulatory factors contributing to ulceration. In essence, the title of Sapolsky’s book gets at the fundamental point that we have fight or flight responses that have evolved to help us run away from ferocious predators in the wild, not pending work report deadlines. In other words, our stress response, fundamentally, has become maladaptive in the 21st century. We live in a time where we are rewarded for our brains, not our brawns. However, for reasons that made sense in the Paleolithic era, when we are faced with a modern stressor, glucose is shuttled to our thighs (not our brains) and our brains instead shut down. So, this maladaptiveness of our biological response to stress, how does it affect us in the long term? Well, in short, stress makes us fat – particularly chronic stress.
The question, then, is how does stress make us fat? What are the physiological consequences of stress? Well, for one, during times of stress, glucose, amino acids and LDL particles are rushed into the bloodstream. When this occurs chronically, it renders us more vulnerable to atherosclerosis and chronically elevated glucose levels, the latter of which is especially conducive to insulin resistance and ultimately type II diabetes. In fact, Sapolsky describes the negative consequences of chronic stress as a sort of allostatic “wear and tear”. What is allostasis? It is constancy through change. It is the ability of your body to stay physiologically healthy despite external disturbances. Allostatic disruptions are fundamental to metabolic syndrome, which is defined as having at least three of the following: increased abdominal (visceral) body fat, hypertension, elevated blood sugar levels, elevated triglycerides, and reduces HDL (good) cholesterol. Metabolic syndrome is a great predictor of future heart disease problems and is closely related to obesity and type II diabetes.
One of the worst consequences of chronic stress is its promotion of fat deposition in the abdomen. Not only is visceral fat a qualifier for metabolic syndrome, it is also readily shuttled to the liver where it is converted into glucose, resulting in elevated blood sugar (yet another determinant of metabolic syndrome). Stress particularly promotes the deposition of fat into abdominal fat cells because, after feeding, it creates a state of both elevated glucocorticoids and insulin during the “recovery phase” subsequent to the stressor – a long term recipe for metabolic disaster.
Alright, so if we accept that chronic stress is metabolically detrimental, although ubiquitous (everywhere around us), what becomes our action plan? Nutrition and exercise are ways in which we can improve our bodies’ resilience to stress. These are ways in which by changing our bodies we change our minds. However, mediation, which deals with altering our conscious state positively (and has been shown to explicitly reduce the stress hormone cortisol – see our recent post) is a way in which our minds change our bodies. It seems obvious, then, that the combining of these two approaches can only be synergistic and therefore beneficial for dealing healthfully with stress.
Metabolic Syndrome. (2014). Retrieved March 15, 2015, from http://www.mayoclinic.org/diseases-conditions/metabolic-syndrome/basics/causes/con-20027243
Sapolsky, R. (2004). Why Zebras Don’t Get Ulcers (3rd ed.). St. Martin’s Griffin.