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Eating Disorders: Research Findings and Directions

Updated on December 19, 2012


Richard Morton documented the first case of anorexia nervosa in 1689. Sir William Gull studied several cases during the 1860s and concluded that the disorder had a psychological origin and gave it its current name, meaning literally "nervous loss of appetite."

But, what does current research on eating disorders reveal?

Increasing incidences of anorexia among boys and men.
Increasing incidences of anorexia among boys and men. | Source


Although women (especially teens and college-age females) are particularly susceptible to eating disorders, until recently, the psychiatric and medical communities thought that only about 10% of the approximately 8 million people with eating disorders were men. Current researchers find that actually 25% are men, with male athletes (swimmers, rowers, and wrestlers) being especially susceptible.

Even thin girls with anorexia nervosa believe they are fat.
Even thin girls with anorexia nervosa believe they are fat. | Source

3 Major Eating Disorders

The American Psychiatric Association (APA)'s criteria (from the DSM IV-TR) sets the criteria or definitions for the three major eating disorders, including:

Anorexia Nervosa

  • Refusal to maintain body weight at or above a minimally normal weight for age and height: Weight loss leading to maintenance of body weight <85% of normal.
  • Intense fear of gaining weight or becoming fat, even though the person is under weight.
  • Disturbance in the way a person's body weight or shape is experienced, undue influence of body weight or shape on self evaluation, or denial of the seriousness of the current low body weight.
  • Amenorrhea (at least three consecutive missed menstrual cycles)

And, there are two types:

  • Restricting type: The person has not regularly engaged in binge-eating or purging behavior (self-induced vomiting or misuse of laxatives, diuretics, or enemas).
  • Binge-eating–purging type: During the current episode of anorexia nervosa, the person has regularly engaged in binge-eating or purging behavior (self-induced vomiting or the misuse of laxatives, diuretics, or enemas).

Bulimia Nervosa

  • Recurrent episodes of binge eating characterized by both:
    1. Within any 2-hour period, the person eats an amount of food that is definitely larger than most people would eat during a similar period of time and under similar circumstances
    2. The person experiences a sense of lack of control over eating during the episode, defined by a feeling that they cannot stop eating or control what or how much they are eating
  • Recurrent inappropriate compensatory behavior to prevent weight gain, including:
    1. Self-induced vomiting
    2. Misuse of laxatives, diuretics, enemas, or other medications
    3. Fasting
    4. Excessive exercise
  • The binge eating and inappropriate compensatory behavior both occur, on average, at least twice a week for 3 months.
  • Self evaluation is unduly influenced by body shape and weight.
  • The disturbance does not occur exclusively during episodes of anorexia nervosa.

There are two types of bulimia nervosa:

  • Purging type: The person has regularly engaged in self-induced vomiting or the misuse of laxatives, diuretics, or enemas.
  • Nonpurging type: The person has used inappropriate compensatory behavior but has not regularly engaged in self-induced vomiting or misused laxatives, diuretics, or enemas.

Binge-eating involves not being able to stop eating.
Binge-eating involves not being able to stop eating. | Source

Binge-eating Disorder

Similar to bulimia, but without the compensatory, excessive behavior, is binge-eating disorder. It is defined as uncontrolled eating without emesis or laxative abuse. It is often, but not always, associated with obesity. Night eating syndrome includes morning anorexia, increased appetite in the evening, and insomnia. These patients can have complete or partial amnesia for eating during the night.

Twin studies reveal genetic factors found in those with eating disorders.
Twin studies reveal genetic factors found in those with eating disorders. | Source

Biological Factors

Past theories that attributed eating disorders to a pituitary gland problem or, later, a fear of motherhood or femininity, have been discarded for a more broad view of eating disorder causes. Increasing evidence proves that eating disorders, although possibly influenced by genetics, are mostly learned behaviors.

Predisposition: Twin and adoptive studies do show a genetic influence toward eating disorders, and there have been recent findings indicating that the serotonin system may play some role in the development of anorexia nervosa.

Biochemical theories are, as yet, inconclusive. Although some researchers think that an altered brain chemistry (involving endorphins) leading to eating disorders may be caused by some unknown factor, it is interesting that often when a person stops abnormal eating behavior, neurotransmitter levels return to normal. So, the biochemical abnormalities may be a consequence rather than a cause.

Psychological Factors

Although treatment specialists are careful not to draw conclusions about the family dynamics of a patient, some correlations have been found. Often the person with an eating disorder lives in certain environments: competitive, semi-closed socially, athletic teams, or college sororities. People who have good relationships with both parents are seen to have the lowest occurrence of eating disorders.

People with anorexia often live with or are from families that are high-achieving, competitive, overprotective, and have poor conflict resolution skills. Mothers of girls with anorexia are frequently described as over-nurturing, over-protective, and demanding.

People with bulimia have higher-than-average incidences of alcoholism, drug addition, obesity, and depression in their families. Mothers of girls with bulimia are sometimes seen as undernurturing, rejecting, and unaffectionate.

Sociocultural Factors

The Western attitude that 'you can never be too thin' proves that there is a cultural element to eating disorders. Eating disorders are often absent in developing countries.

Roberta Seid notes, "Our culture has elevated the pursuit of a lean, fat-free body into a new religion." "Indeed, anorexia nervosa could be called the paradigm of our age, for our creed encourages us all to adopt the behavior and attitudes of the anorexic."

Body image for girls
Body image for girls | Source

Body Image and the Media

Nowhere is this 'religion' more apparent that in how women's bodies are represented in the media.

The thought that media is contributing to current cases of eating disorders that usually include a distorted body image, is supported by the following findings.

  • Researchers have seen a substantial increase in eating disorders over the past half century.
  • Before the 1970s, eating disorders were usually found among upper-middle class women in Western cultures. That, however, is no longer the trend. Increased percentages of those with eating disorders have spread to all socioeconomic classes and younger age groups.
  • Models, actors, and Miss Americas have progressively decreased to the thinnest 5 to 10 percent of American women. When shown pictures of unnaturally thin models, studies show that women of normal weight often report an increase in emotions and attitudes linked to eating disorders, such as depression, shame, and dissatisfaction with their own bodies.


For a description of current eating disorder treatment options, see: How to Treat Eating Disorders.

DSM-V: Revamping Eating Disorder Definitions

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) is scheduled for release in May of 2013. The contents of this Hub article will be adjusted, if needed, upon the book's release.

Regarding updates to the manual: "The effort is very important because it infuses data much more directly into the discussions about the next set of eating disorder diagnoses," says the effort's principal investigator, Stephen Wonderlich, PhD, Chester Fritz Distinguished Professor at the University of North Dakota School of Medicine and Health Sciences.


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