Eating Disorders: The Method behind the Madness

When faced with stress, especially in college, many students develop different coping mechanisms, both good and bad. While some people release steam by going to the gym, hanging with friends, and napping, others develop unhealthy habits such as binge drinking and eating disorders in the attempt to fight off the stress in their lives. Because of the noticeably strong correlation specifically between stress and eating disorders such as anorexia and bulimia, researchers have begun to look for physiological and psychological explanations as to why people, girls in particular, turn to harmful eating-related behaviors to counteract stressful situations.

The main physiological systems in charge of responding to stress are the sympathetic nervous system and the hypothalamus-pituitary-adrenal axis (Het et al., 2014). The sympathetic nervous system releases epinephrine and norepinephrine from the adrenal medulla for a short-term adaptation to a stressful environment. The hypothalamus-pituitary-adrenal axis then releases corticotropin-releasing hormones, adrenocorticotropic hormones, and cortisol to maintain homeostasis (Het et al., 2014). At resting conditions, people with either anorexia or bulimia display a decrease in sympathetic nervous system activity and an increase in hypothalamus-pituitary-adrenal axis activity compared to healthy individuals. This could indicate a predisposing condition causing the development of an eating disorder because their stress response systems are primarily abnormal (Het et al., 2014). Researchers were able to determine this by measuring the concentration of cortisol in their saliva.  Cortisol also displays a type of circadian rhythm with its cortisol awakening response, which was used to indicate hypothalamus-pituitary-adrenal axis activity as well (Het et al., 2014).

While these results have been very helpful in figuring out the difference in stress system activity for those suffering from eating disorders, there has been a lot of contradicting evidence about the difference in their stress systems’ responses. This has been due to small sample sizes and ineffective stress induction methods (Het et al., 2014). That is why Het et al. sought to compare the physiological and psychological responses to stress of people with and without eating disorders using a larger sample size and the Trier Social Stress Test as an appropriate stress inducing method (Het et al., 2014). They used a sample size of 26 female inpatients suffering from either anorexia or bulimia. They decided to clump the two eating disorders together because they believed that both eating disorders shared the same core psychopathology even though they differed in the means for controlling eating patterns (Het et al., 2014). This could have skewed their data because there is no way to know if there is a physiological process that makes the distinction between the two disorders.

In order to test the patients’ response to stress, Het et al. had to find a way to administer the stress in the first place. As previously stated, they chose to do so by using the Trier Social Stress Test. It combined tests such as convincing others to hire them for a ‘dream job’ and counting backwards from 2043 in steps of 17 as fast as they can, acts that would make anybody break out in a nervous sweat (Het et al., 2014). Het et al. would then take saliva samples before and after the stress test and measure the difference in cortisol and sympathetic nervous system levels. These samples showed that compared to the healthy controls, participants with eating disorders showed a decrease in cortisol levels (hypothalamus-pituitary-adrenal axis activity) after the stress test (Het et al., 2014). In order to test stress’s effect on sympathetic nervous system activity, each participant’s heart rate variability was taken. Low-frequency heart rate variability indicated both parasympathetic and sympathetic activity. Results showed that there was no difference between groups of participants in sympathetic activity after the stress test (Het et al., 2014). For their last procedure, Het et al. tested the participants’ psychological response to stress by administering a Positive and Negative Affect Schedule. Results showed that both groups showed an increase in negative affect after the stress test, but eating disorder participants displayed a higher negative affect to begin with (Het et al., 2014). This could mean that their unhealthy response to stress could be due to their already blunted psychological processes.

After gathering their results, Het et al. sought to explain why people with eating disorders tend to have lower hypothalamus-pituitary-adrenal axis activity in response to stress. One explanation they came up with was that it was due to the fact that their participants were inpatients that were recently introduced to a proper eating regiment. By eliminating fasting as a constant trigger for a stress response, the hypothalamus-pituitary-adrenal axis activity would drop (Het et al., 2014). This shows that ones’ body will change in response to ones’ coping mechanisms in order to respond to them as if they were the stress signal to begin with. Although their findings were different than expected, they indicated that there is a connection between eating disorders, our bodies, and our minds. They should continue their work by individually testing patients with anorexia and patients with bulimia to see if there is a difference in physiological processes between the two. Even so, they found that anorexia and bulimia are not necessarily a conscious decision made by women trying to look thinner, but rather a disorder that some people may be physiologically prone to developing in order to manage stress.

Credit: Het, S., Vocks, S., Wolf, J., Hammelstein, P., Herpertz, S., Wolf, O. (2014). Blunted neuroendocrine stress reactivity in young women with eating disorders. Journal of Psychosomatic Research, 78(2015), 260-267.