There is no single cause for eating disorders. Although concerns about weight and body shape underlie all eating disorders, the actual cause of these disorders appear to result from a convergence of many factors, including cultural and family pressures and emotional and personality disorders. Genetics and biologic factors may also play a role.

Personality Disorders

A 2000 study reported that people with eating disorders tended to share similar personality traits, including low self-esteem, dependency, and problems with self-direction. Researchers have been attempting to determine specific personality disorders or behavioral characteristics that might put people at higher risk for one or both of the eating disorders. Some studies have reported the following personality disorders linked to particular eating disorders:

Avoidant personalities, mostly in anorexia. Such people are generally high functioning, persistent, and perfectionists. Dependent personalities, mostly seen in anorexia. (This group is usually overcontrolled and withdrawn.) Borderline and histrionic personalities, mostly seen in bulimia. (Such individuals are emotionally uncontrolled and impulsive.) Narcissism in both anorexia and bulimia. Should be noted that any of these personality traits can appear in either patients with bulimia or anorexia; some experts believe that the patient’s specific personality disorders, rather than whether they are anorexic or bulimic, may be the more important factor in determining treatment choices.

Avoidant Personalities

Some studies indicate that as many as a third of anorexia restrictors have avoidant personalities. This personality disorder is characterized by the following: Being a perfectionist.
Being emotionally and sexually inhibited.
Having less of a fantasy life than people with bulimia or without an eating disorder.
Not being rebellious, or usually perceived as always being “good.” Being terrified of being ridiculed or criticized or of feeling humiliated. People with anorexia are extremely sensitive to failure, and any criticism, no matter how slight, reinforces their own belief that they are “no good.” The person with both anorexia and avoidant personality disorder may hypothetically develop a behavioral and eating pattern as follows:

For such individuals, achieving perfection, with all that that involves, is the only way to obtain love.

Part of the drive for perfection and love is being trouble-free and attaining some ideal image of thinness. The individual is driven to demand nothing, including food.

Failure is inevitable, since being loved by another person rarely has anything to do with being perfect. (In fact, people who are always seeking perfection can alienate others around them.)

Failure to achieve love is followed by a sense of being even more imperfect (which is equivalent to being fat) and a renewed sense of striving for perfection (ie, becoming even thinner).

Although people with eating disorders are not typically suicidal, one expert described her anorexic patients as having a total lack of self, well beyond having low self-esteem. The process of not-eating, then, becomes an act of passive revenge on those whose love is always out of reach: “See? I am slowly disappearing, and you will be very sad when I am gone.”

Borderline Personalities

Studies indicate that almost 40% of people who are diagnosed with bulimic anorexia (who lose weight by bingeing and purging) may have borderline personalities. Such people tend to have the following characteristics:

Having unstable moods, thought patterns, behavior, and self-images. People with borderline personalities have been described as causing chaos around them by using emotional weapons such as temper tantrums, suicide threats, and hypochondriasis. Being frantically fearful of being abandoned. Being unable to be alone. Having difficulty controlling their anger and impulses. (In fact, between one-quarter and one-third of people with bulimia have impulsive symptoms.) Being prone to idealize other people. Frequently this is followed by rejection and by disappointment.

Some research has suggested that the severity of this personality disorder predicts difficulty in treating bulimia, and it might be more important than the presence of psychological problems, such as depression.


Studies have also found that people with bulimia or anorexia are often highly narcissistic and manifest the following personality traits:

Having an inability to soothe oneself.

Having an inability to empathize with others.

Having a need for admiration. Being hypersensitive to criticism or defeat.

Accompanying Emotional Disorders Between 40% and 96% of all eating-disordered patients experience depression and anxiety disorders. Depression, anxiety, or both is also common in families of patients with eating disorders. It is not clear if emotional disorders, particularly obsessive-compulsive disorder (OCD), are actual causes of the eating disorders, increase susceptibility to them, or share common biologic cause.

Obsessive-Compulsive Disorder (OCD)

Obsessive-compulsive disorder is an anxiety disorder that occurs in up to 69% of patients with anorexia and up to 33% of patients with bulimia. In fact, some experts believe that eating disorders are just variants of OCD. Obsessions are recurrent or persistent mental images, thoughts, or ideas, which may result in compulsive behavior, repetitive, rigid, and self-prescribed routines that are intended to prevent the manifestation of the obsession. Women with anorexia and OCD may become obsessed with exercise, dieting, and food. They often develop compulsive rituals, eg, weighing every bit of food, cutting it into tiny pieces, or putting it into tiny containers. The presence of OCD with either anorexia or bulimia does not, however, appear to have any effect on whether a patient improves or not.

Other Anxiety Disorders

A number of other anxiety disorders have been associated with both bulimia and anorexia. Phobias. Phobias often precede the onset of the eating disorder. Social phobias, in which a person is fearful about being humiliated in public, are common in both eating disorders.
Panic Disorder. Panic disorder often follows the onset of an eating disorder. It is characterized by periodic attacks of anxiety or terror ( panic attacks ). Post-Traumatic Stress Disorder. One study of 294 women with serious eating disorders reported that 74% of them recalled a traumatic event and more than half exhibited symptoms of post-traumatic stress disorder (PTSD), which is an anxiety disorder that occurs in response to violent circumstances.

Depression is common in people with eating disorders, particularly anorexia. Depression and eating disorders are also linked to a similar seasonal pattern, as indicated by the following observations:

In many people, depression is more severe in darker winter months. Similarly, a subgroup of bulimic patients suffers from a specific form of bulimia that worsens in winter and fall. Such patients are more apt to have started bingeing at an earlier age and to binge more frequently than those whose bulimia is more consistent year round. Onset of anorexia appears to peak in May, which is also the peak month for suicide.

Major depression is unlikely to be a cause of eating disorders, however, because treating and relieving depression rarely cures an eating disorder. The severity of the eating disorder is also not correlated with the severity of any existing depression. In addition, depression often improves after anorexic patients begin to gain weight.
Dysmorphic Disorder

Body dysmorphic disorder involves a distorted view of one’s body that is caused by social, psychologic, or possibly biologic factors. It is often associated with anorexia or bulimia, but it can also occur without any eating disorder. People with this disorder also commonly suffer from emotional disorders, including obsessive-compulsive disorder and depression.

Muscle Dysmorphia

Experts are also increasingly reporting a disorder in which people have distorted body images involving their muscles. It tends to occur in men who perceive themselves as being “puny” and results in excessive body building, preoccupation with diet, and social problems.

Negative Family Influence

Negative influences within the family play a major role in triggering and perpetuating eating disorders. Some studies have produced the following observations and theories regarding family influence.

Insecure Infancy

Some experts theorize that parents who fail to provide a safe and secure foundation in infancy may foster eating disorders. In such cases, children experience so-called insecure attachments . They are more likely to have greater weight concerns and lower self-esteem than are those with secure attachments.

Parental Personalities

One study found that 40% of nine to 10 year-old girls try to lose weight generally with the urging of their mothers. Some studies have found that mothers of anorexics tend to be over-involved in their child’s life, while mothers of people with bulimia are critical and detached. Some research strongly implicates overly critical fathers, brothers, or both in the development of anorexia in both girls and boys.

Family History of Addictions or Emotional Disorders

Studies report that people with either eating disorder are more likely to have parents with alcoholism or substance abuse than are those in the general population. Parents of people with bulimia appear to be more likely to have psychiatric disorders than parents of patients with anorexia.

History of Abuse

Women with eating disorders, particularly bulimia, appear to have a higher incidence of sexual abuse; studies have reported sexual abuse rates as high as 35% in women with bulimia.

Family History of Obesity

People with bulimia are more likely than average to have an obese parent or to have been overweight themselves during childhood.

At least one study has reported that the most positive way for parents to influence their children’s eating habits and prevent weight problems and eating disorders is to have healthy eating habits themselves. Problems Surrounding Birth
In some studies people with anorexia have reported a higher than average incidence of problems during the mother’s pregnancy or after birth. These problems include the following:

  • Infection.
  • Physical trauma.
  • Seizures.
  • Low birth weight.
  • Older maternal age.

Some experts believe, then, that such patients experienced some injury to the brain while in the womb that predisposed them to eating problems in infancy and subsequent eating disorders later in life. Studies have suggested that people with anorexia often had stomach and intestinal problems in infancy.

Genetic Factors

Anorexia is eight times more common in people who have relatives with the disorder, and some experts estimate that genetic factors may influence more than half of the variances in eating disorders. For example, a 2000 study reported that twins had a tendency to share specific eating disorders (anorexia nervosa, bulimia nervosa, and obesity). Some evidence has reported an association with genetic factors responsible for serotonin, the brain chemical involved with both well-being and appetite. Some inherited traits that might make someone susceptible to eating disorders include the following:

A genetic propensity toward thinness caused by a faster metabolism and reinforced by cultural approval could predispose some people to develop anorexia. An inherited propensity for obesity could also trigger eating disorders to compensate.
Inherited personality traits also play some causal role.

Cultural Pressures

One interesting anthropologic study reported the following observations:

During historical periods or in cultures where women are financially dependent and marital ties are stronger, the standard is toward being curvaceous, possibly reflecting a cultural or economic need for greater reproduction.
During periods or in cultures where female independence has been possible, the standard of female attractiveness tends toward thinness.

hether or not the current Western cultural pressure is for fewer children, the response of the media to both the cultural drive for thinness and overproduction of food play major roles in triggering obesity and eating disorders. On the one hand, advertisers heavily market weight-reduction programs and present anorexic young models as the paradigm of sexual desirability. Clothes are designed and displayed for thin bodies in spite of the fact that few women could wear them successfully.

One study reported that teenage boys and girls who made strong efforts to look like celebrities of the same sex were more likely to be constant dieters. On the other hand, food is overproduced, and the media floods the public, and particularly women and children, with attractive ads for consuming foods, both at home and out of the home. And, the emphasis is on junk foods. In a country where obesity is epidemic, young women who achieve thinness believe they have accomplished a major cultural and personal victory; they have overcome the temptations of junk food and, at the same time, created body images idealized by the media. Weight loss brings a feeling of triumph over helplessness. This sense of accomplishment is often reinforced by the envy of heavier companions who perceive the anorexic friend as being emotionally stronger and more sexually attractive than they are. Excessive Athleticism and the Female Athlete Triad. The cultural attitude toward physical activity is a fitting companion to the general disordered attitude regarding eating. Americans are encouraged to admire physical activity only as an intense competitive effort that few can attain, leaving most people in their armchairs as spectators.

In the small community of athletes, excessive exercise plays a major role in many cases of anorexia (and, to a lesser degree, bulimia). In young female athletes, anorexia postpones puberty, allowing them to retain a muscular boyish shape without the normal accumulation of fatty tissues in breasts and hips that may blunt their competitive edge. Many coaches and teachers compound the problem by overstressing calorie counting and loss of body fat. Some over-control the athletes’ lives and are even abusive to an athlete that goes over the weight limit. (Male athletes are also vulnerable to their coaches’ influence and anorexia is also a problem among this group.)

In response, people who are vulnerable to such criticism may lose excessive weight, which has been known to be deadly even for famous athletes. The term “female athlete triad” in fact, is now a common and serious disorder facing young female athletes and dancers and describes the combined presence of the following problems:

Eating disorders. Amenorrhea (absence or irregular menstruation). Evidence is mounting that overly restricting calories may be more important than low weight in causing menstrual problems. Studies suggest that amenorrhea occurs even in women with normal weight if they severely diet. Osteoporosis. Bone loss, on the other hand, appears to be related to low weight. The more severe the weight loss, the more bone is lost.

In one study, female athletes who consumed a high-fat diet (35% of daily calories) performed longer and with greater intensity than those with a standard athletic low-fat diet (27% of daily calories). And such a diet appeared to be more estrogen-protective. Hormonal Abnormalities. Hormonal problems are rampant in eating disorders and include chemical abnormalities in the thyroid, the reproductive regions, and areas related to stress, well-being, and appetite. Many of these chemical changes are certainly a result of malnutrition or other aspects of eating disorders, but they also may play a role in perpetuating or even creating susceptibility to the disorders.

The primary setting of many of these abnormalities originate in a small area of the brain called the limbic system. A specific system called hypothalamic-pituitary-adrenal axis (HPA) may be particularly important in eating disorders. It originates in the following regions in the brain:

Hypothalamus. The hypothalamus is a small structure that plays a role in controlling our behavior, such as eating, sexual behavior and sleeping, and regulates body temperature, emotions, secretion of hormones, and movement.

The Pituitary Gland. The pituitary gland develops from an extension of the hypothalamus downwards. It is involved in controlling thyroid functions, the adrenal glands, growth and sexual maturation.

Amygdala. This small almond-like structure lies deep in the brain and is associated with regulation and control of major emotional activities, including anxiety, depression, aggression, and affection. Stress Hormones. The HPA systems trigger the production and release of stress hormones called glucocorticoids, including the primary stress hormone cortisol. Chronically elevated levels of stress chemicals have been observed in patients with anorexia and bulimia. Cortisol is very important in marshaling systems throughout the body (including the heart, lungs, circulation, metabolism, immune systems, and skin) to deal quickly with any threat. Among the specific effects is inhibition of neuropeptide Y (NPY), a powerful appetite stimulant that also has anti-anxiety properties. This process may serve as a biologic link between extreme stressful conditions in a young person’s life and the later development of anorexia, although some imaging studies indicate that stress-hormone related changes occur after anorexia has developed. More work is needed to determine if changes in stress hormones are a cause or result of eating disorders.

Release of Neurotransmitters. The HPA system also releases certain neurotransmitters (chemical messengers) that regulate stress, mood, and appetite and are being heavily investigated for a possible role in eating disorders. Abnormalities in the activities of three of them, serotonin, norepinephrine, and dopamine, are of particular interest. Serotonin is involved with both well-being and appetite (among other traits), and norepinephrine is a stress hormone. Abnormalities in both have been observed in patients who binge and in those with anorexia or bulimia. Dopamine is involved in reward-seeking behavior, so deficiencies might create a more intense need for rewards, such as carbohydrates. Studies on dopamine abnormalities have been mixed, however.

Low-Leptin Levels. Leptin is a hormone that appears to trigger the hypothalamus to stimulate appetite, and low levels have been observed in people with anorexia and bulimia.

Low Reproductive HormonesThe hypothalamic-pituitary system is also responsible for the production of important reproductive hormones that are severely depleted in anorexics. Although most experts believe that these reproductive abnormalities are a result of anorexia, others have reported that in 30% to 50% of people with anorexia, menstrual disturbances occurred before severe malnutrition set in and remained a problem long after weight gain, indicating that hypothalamic-pituitary abnormalities precede the eating disorder itself.

Compensating for Mood Swings during Binge-Purging CyclesSerotonin Imbalances. Low levels of serotonin have been observed not only in eating disorders but also in depression. One theory for the persistence of the binge-purge cycle in bulimia involves restoring serotonin imbalances and so improving mood. It involves the following:

Bingeing elevates tryptophan, a compound found in food, particularly carbohydrates, that is essential to the production of serotonin in the brain. People may binge then in order to produce serotonin and improve mood.An initial increase in tryptophan, however, produces depression in some people. Both events are consistent with a study on young people with bulimia who reported negative moods before and even worse moods right after bingeing. Such depression may become associated with guilt over bingeing and therefore the need to purge. Right before and after a purge cycle, however, studies report an improvement in mood, which might indicate the delayed increase in serotonin triggered by the tryptophan. The heightened mood after the purge cycle may be due to stimulation of natural opioids that occur during this process.
The binge-purge cycle then might be stimulated by chemical changes and perpetuated by feelings of guilt and depression after bingeing and release from guilt and euphoria during and after purging. Infections In some cases, infection has been associated with anorexia. Immune factors released to fight these infections may cause inflammation and injury in the areas of the brain that affect appetite and behavior. Streptococcal Infection. Research has found a link between anorexia and group A beta-hemolytic streptococcal (GABHS) bacteria, the cause of strep throat. GABHS has already been identified as a trigger of a rare form of obsessive-compulsive disorder (OCD) in children, which often accompanies eating disorders. Epstein Barr. Epstein Barr, the virus that causes mononucleosis has also been associated with the development of anorexia.
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