Obesity is becoming an increasingly common condition throughout the world, especially in North America. The prevalence of overweight or obese children and adolescents increased from 4% to 18% globally from 1975 to 2016 [6]. In 2016, there were 1.9 billion adults, 39% of the global population,that were overweight and 650 million (13%) that were obese [1]. Recently, evidence has shown that stress, particularly the increase of the glucocorticoid (a group of corticosteroids which metabolize carbohydrates, proteins, and fats) stress hormone cortisol, is a key factor in the development of obesity in certain individuals [2]. Stress has been shown to have an effect on the brain’s responses to food in both lean and obese adults, with both of them having reactions to food cues in areas of the brain associated with reward and cognitive control [3]. With one third of people around the world reporting feeling stressed, worried, and/or angry in 2019, the effects stress has on the eating behaviors of people is slowly becoming a dire health risk to the global population, especially considering the negative effects the pandemics has had on individuals.

Obesity is defined as “abnormal or excessive fat accumulation that may impair health.”[1] With 35.7% of adults in the United States being obese, obesity is one of the most important risk factors for potentially life-threatening health problems (including type II diabetes, osteoarthritis, cardiovascular disease and certain cancers) [3]. Yvonne Yau (a PhD student at McGill University) and Dr. Marc Potenza (a board-certified psychiatrist with sub-specialty training and certification in addiction psychiatry and Professor of Psychiatry, Child Study and Neuroscience at the Yale University School of Medicine), wrote in an essay published in the Edizioni Minerva Medica, that the term stress ”refers to processes involving perception, appraisal, and response to noxious events of stimuli.” [3]. It is the “real or perceived threat to homeostasis” [4] which can be both emotionally and physiologically challenging to individuals [3].

An article published in Harvard Health Publishing stated that the hormones unleashed by stress and the effects of high-fat/sugary “comfort foods” are what push people to overeat, or in other words “stress eat” [5]. Yvonne Yau and Dr. Marc Potenza claim that “Acute stress activates adaptive responses, but prolonged stress leads to “wear-and-tear” of the regulatory systems, resulting in biological alterations that weaken stress-related adaptive processes and increase disease susceptibility” [3]. While long term stressors can lead to overeating, acute stress can cause an individual’s appetite to shut down. This is due to the nervous system sending messages to the adrenal glands to release a hormone called epinephrine (adrenaline) which triggers the fight-or-flight response in an individual, causing the body to temporarily put eating on hold. Prolonged stress has a completely different effect. Instead of releasing epinephrine, the adrenal gland releases a hormone called cortisol which increases appetite [5], with a preference for energy-dense food (comfort food) [3]. Cortisol may also increase motivation, including the motivation to eat [5].

Stress challenges an organism’s natural homeostasis, which may cause said organism to react to stress by producing physiological responses in order to regain some form of equilibrium that was lost due to the impact of the stressor [3]. One of said homeostases that are disrupted is the feeding behaviour of individuals [3]. The shift from decreased to increased food intake depends on the adaptations in the reward circuitry in the brain [6]. A study on Chronic stress increasing susceptibility to food addiction, by Wei et al., found that “the dysregulation of the reward system increases vulnerability to palatable food dependency.” When stress shifted from being acute to chronic, the reward system in the brain became unregulated which led to the development of food addiction [6]. Yvonne Yau and Dr. Marc Potenza specified that “Although dopamine release is not equivalent to addictive properties, dopamine has been associated with reward sensitivity, conditioning and control with respect to both food and drugs of abuse. Increased dopamine release has been reported in response to food and food cues, both of which are crucial aspects of food intake.” With repeated stimulation of the dopaminergic reward pathway, there is a possibility that it could trigger adaptations that promote compulsive behaviour in relation to food [3].

Despite there being plenty of data suggesting its existence, the presence of food addiction is still questioned in some parts of the scientific community. Due to this, food addiction in clinical settings is often overlooked and left untreated. Further research on stress related eating and how to prevent it is needed in order to develop better and more suitable treatments for eating disorders, especially binge eating disorders. Stress is something everyone experiences at some point in their lives. However, by recognizing the impact it has on our eating habits, we may be able to find ways to counter the negative effects.

References

1. World Health Organization. (2021, June 9). Obesity and overweight. https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight#:~:text=The%20prevalence%20of%20overweight%20and,19%25%20of%20boys%20were%20overweight
2. van der Valk, E. S., Savas, M., van Rossum, E. F. C. (2018). Stress and obesity: Are there more susceptible individuals? Current obesity reports, 7(2), 193-203. https://doi.org/10.1007/s13679-018-0306-y
3. Yau, Y. H., & Potenza, M. N. (2013). Stress and eating behaviors. Minerva endocrinologica, 38(3), 255–267.
4. Scott, K. A., Melhorn, S. J., & Sakai, R. R. (2012). Effects of Chronic Social Stress on Obesity. Current obesity reports, 1(1), 16–25. https://doi.org/10.1007/s13679-011-0006-3
5. Harvard Medical School. (2021, February 15). Why stress causes people to overeat. Harvard Health Publishing. https://www.health.harvard.edu/staying-healthy/why-stress-causes-people-to-overeat
6. Wei, N. L., Quan, Z. F., Zhao, T., Yu, X. D., Xie, Q., Zeng, J., Ma, F. K., Wang, F., Tang, Q. S., Wu, H., & Zhu, J. H. (2019). Chronic stress increases susceptibility to food addiction by increasing the levels of DR2 and MOR in the nucleus accumbens. Neuropsychiatric disease and treatment, 15, 1211–1229. https://doi.org/10.2147/NDT.S204818
7. Das, S., O’Keefe, J. (2006). Behavioral cardiology: Recognizing and addressing the profound impact of psychological stress on cardiovascular health. Current Atherosclerosis Reports, 8, 111–118. https://doi.org/10.1007/s11883-006-0048-2