Classifying Eating Disorders: A Closer Look at Anorexia and Bulimia

Recently, efforts have been made to increase awareness about mental health through pop culture. Netflix Original shows such as 13 Reasons Why and To the Bone highlight various aspects of mental health such as major depression and eating disorders, and they project these to broad audiences. Unfortunately, of all mental health conditions, eating disorders have the highest mortality rate. However, how eating disorders such as anorexia nervosa and bulimia nervosa are distinguished and categorized is still a topic of discussion among psychologists today.

How are the two eating disorders currently characterized?

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According to the DSM IV both anorexia nervosa and bulimia nervosa are classified as psychological eating disorders characterized by atypical eating habits as a means to control or reduce one’s body weight. While the most common behaviors associated with anorexia and bulimia are self-starvation and purging, respectively, there is a binging-purging category of anorexia nervosa. Therefore, the behaviors most commonly associated with each of the two main types of eating disorders is not what distinguishes them from each other. Instead, psychologists have defined anorexia nervosa as the maintenance of a significantly low body weight (a BMI below 17.5) and distorted body image while individuals with bulimia nervosa are typically of normal body weight, but do display behaviors such as purging and over-exercising. In the movie To the Bone, Ellen, played by Lily Collins, had a very low body weight, yet still exhibited behaviors such as over-exercising to the point where she did so many sit ups per day that she was left with a bruised spine. Collins used her own personal experiences with eating disorders to inform her acting.

Why are anorexia and bulimia classified as separate disorders?

While both anorexia nervosa and bulimia nervosa are similar in terms of psychopathology and many patients move between these two disorders over time, psychologists and medical professionals maintain this distinction between anorexia nervosa and bulimia nervosa instead of adopting the transdiagnostic model of eating disorders because anorexia and bulimia do not have a common causality. In particular, there are psychological differences as well as biological differences associated with each disorder.

What are the Psychological Differences between the two eating disorders?

From a psychological perspective, anorexic individuals tend to exhibit perfectionist attitudes in order to feel a sense of control while bulimic individuals tend to exhibit more dichotomous attitudes and suffer from impulse control. Therefore, these psychological factors, in part, help explain why some people are more susceptible than others. In addition to personality differences, neurobiological differences between the two disorders help to distinguish the two disorders.

What are the Biological Differences between the two eating disorders?

Studies have suggested that neurotransmitter interactions differ between anorexic and bulimic individuals. Brain serotonin , a type of neurotransmitter, is associated with anxious behavior, obsessional behaviors, and extremes of impulse control. Levels of brain serotonin differ significantly in anorexic individuals compared to bulimic individuals. Studies have found that individuals with anorexia nervosa typically have lower levels of serotonin. However, following long term recovery, anorexic individuals have been found to have significantly elevated levels of serotonin compared to healthy individuals, which correspond to anxiety and obsessive behavior. These findings suggest that since starvation lowers serotonin levels because neurotransmitters are synthesized from food, starvation may cause individuals with anorexia to feel less anxious. Conversely, serotonin levels in bulimic individuals tend to fluctuate to lower than normal levels when the individual is hungry. This helps to explain why bulimic individuals tend to binge because serotonin acts as an appetite suppressant.

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It’s important to consider the biological and psychological perspectives in understanding the two disorders. While sociocultural influences can help us gain a better understanding of the psychopathology of the two, such factors do not adequately explain why some individuals are more susceptible than others. Trends in the average BMI of Miss Universe pageant contestants are indicative of such cultural influences on body weight. Most notably around 1990 the average BMI for Miss Universe contestants dropped into the underweight category while the average American woman had moved into the overweight range. However, sociocultural factors such as the media’s influence on body image do not completely explain why certain people are more susceptible to disordered eating habits. While there is a general awareness of the “thin ideal”, internalization of the “thin ideal” can largely be attributed to factors beyond sociocultural influence, such as biological and psychological factors.

While the distinction between the two disorders may seem nuanced, it’s important to understand why psychologists have characterized each of the eating disorders in its current form because it allows us to better understand the psychopathology of the individual and how to better treat them. Through both a psychological as well as biological perspective we can better justify and explain the distinction between the two.

 

About the Author

Gazal Arora is an undergraduate Cellular Biology major at the University of Georgia. When she’s not studying at the Science Library, she can be found hiking, reading, or Snellibrating. For more information you can email her at ga25144@uga.edu or follow her on Twitter: @gazalarora_.