There are few sounds that unanimously elicit the same emotion in us, whether we live in cities or in the country, hold jobs as CEOs or wildlife conservationists; there’s that sense of childish and fleeting glee at the sound of an ice-cream truck gliding down a side street, that rippling discomfort at the screeching grind of nails on a chalk board, and that intrusive sense of “ugh” upon hearing the harassing, monotone honk of an alarm clock on a Monday morning. If you’re like me, you hit the snooze in a half-conscious state, and eventually lurch out of bed to realize you only have 20 minutes until that devastatingly early work meeting. You make it in time, a little disheveled and sweaty but committed to pretending this is a casual arrival, trying to hide a suspicious shortness of breath and the fact that you can’t remember if deodorant was something that happened this morning. And then! Then, there’s that glorious moment of relief as you glance from PowerPoint slides and schematics to the conference table where a lovely pile of pillow-soft, golden innertubes rest. Doughnuts. You sit casually, and like Bilbo after the ring to rule them all, you snatch one, feeling a sense of sweet relief and immense satisfaction before it even hits your lips.
We’ve all been in a similar situation, when “stress-induced eating” strikes and we find ourselves cramming chips, cookies and nachos down our throats. And, as researchers have found, there is indeed an underlying, physiological reason for this sense of relief after we engage in this pattern of food intake. As it turns out, stress-induced activation of the hypothalamic-pituitary-adrenal axis stimulates corticotropin-releasing hormone (CRH) and glucocorticoid secretion from the hypothalamus and adrenal cortex, respectively. At the onset of stress exposure (e.g. after realizing your late for that meeting), CRH acts to reduce appetite as insulin levels decrease and fat stores are broken down into useable energy, readying the flight-or-fight response (review: Sapolsky 2004 p. 72). In contrast, once all that energy has been broken down and either used or needs to be repackaged into fat cells, glucocorticoid levels are high and insulin levels are on the rise, stimulating food intake to supply the energy to replenish or repackage (review: Sapolsky 2004 p. 73).
Animal studies reveal that while glucocorticoids increase the amount of food consumed, insulin is more likely to increase preference for foods with more fat and sugar (review: Finch and Tomiyama 2014). The kicker (and why that doughnut felt so good) is that the consumption of a lot of fatty, sugary foods can diminish both physiological and behavioral measures of stress responding. So, not only are glucocorticoids released in response to stress, but their release can increase food intake which can also serve as a negative feedback mechanism, turning off the stress response (review: Finch and Tomiyama 2014). Interestingly, a greater increase in circulating glucocorticoids after a high-fat meal is more common in women with a history of major depressive disorder (MDD; Kiecolt-Glaser et al. 2015) and in individuals who engage in stress-induced hyperphagia (review: Sapolsky 2004 p. 75). A cardinal symptom of depression is weight gain, which could be associated with reduced negative feedback of the stress response by glucocorticoids and by glucocorticoid-associated food consumption.
Unfortunately, overeating to activate a negative feedback mechanism with reduced sensitivity can ultimately lead to the accumulation of visceral fat which is linked to cardiovascular disease, adult diabetes and with damage to the pancreas, insulin-dependent diabetes (review: Sapolsky 2004, p. 63). Through therapy and medication, and if the individual realizes the threat of overeating to overall health, it may be possible for patients suffering from MDD to terminate this vicious cycle (Magnan et al. 2017).
Finch, L.E., Tomiyama, A.J. (2014) Stress-induced eating dampens physiological and behavioral stress responses. Nutrition in the Prevention and Treatment of Abdominal Obesity. Elsevier Inc.
Kiecolt-Glaser, J.K., Habash, D.L., Fagundes, C.P., Andridge, R., Peng, J., Malarkey, W.B., Belury, M.A. (2015) Daily stressors, past depression, and metabolic responses to high-fat meals: A novel path to obesity. Biological Psychiatry, 77: 653-60
Magnan, R.E., Shorey Fennell, B.R., Brady, J.M. (2017) Health decision making and behavior: The role of affect-laden constructs. Soc Personal Psychol Compass, 11:e12333
Sapolsky, R.M. (2004) Why zebras don’t get ulcers: A guide to stress, stress related diseases, and coping. New York: W.H. Freeman.