What is bulimia nervosa?

What causes bulimia nervosa?

Researchers have several theories about the causes of bulimia nervosa, but no single theory accounts for all possible causes and symptoms. Most of the current theories about the disorder relate to self-perceptions about body image (size, shape, and weight), mood and depression, and genetics, but researchers and clinicians do not know why one person develops the disorder while another person with a very similar profile does not. Researchers are studying possible cause-and-effect relationships between bulimia nervosa and other mental disorders commonly associated with it. Pinpointing the causes of bulimia nervosa has proven difficult because the disorder has both mental and physical components, and it develops in many age groups, races, socioeconomic classes, and both sexes.

Current Theories

One popular theory for the development of bulimia nervosa, the “cognitive behavior model” theory, presumes that the affected person is unhappy with his or her body size and shape and associates feeling full with being fat. This perception triggers emotions of anxiety, depression, anger, and self-loathing. To the person with bulimia nervosa, purging or excessive exercise becomes a way of removing the “fat feeling” and undesirable feelings and emotions that go with it. The affected person feels better emotionally after purging or exercising, and the feeling of improved well-being positively reinforces the behavior. Some psychological risk factors, according to this model, are an individual’s concern with his or her body size, shape, a propensity for perfectionism, and obsessive traits

Several other theories are grouped under “interpersonal and sociocultural models.” These theories stem from the observation that bulimia nervosa often coexists with another mental disorder, such as depression, and that an individual feels pressure from society, particularly peers, family members, and the media to be thin. This pressure, which may contribute to an often unrealistic perception of a “thin ideal” and depression, may trigger bulimic behaviors such as purging after binge eating.

The “pathophysiologic model” suggests that brain chemistry causes the disorder. Levels of chemicals such as serotonin, some types of opioids, endorphins, estrogen, and a peptide called cholecystokinin have been found to be abnormal in individuals with bulimia nervosa. Abnormal levels of some of these chemicals are also found in people with other mental disorders, including substance use disorder. Eating can also cause changes in the levels of these chemicals. However, researchers have yet to show that these imbalances cause bulimia nervosa—the abnormal levels could be a result, rather than cause, of the behavior.

Models for the biologic basis of eating disorders are being explored through family, twin, and molecular genetic studies. Family and twin studies have consistently shown that bulimia nervosa runs in families (as do other eating disorders). Many recent molecular genetic studies have identified several possible genes, but no consistent association between a particular gene and bulimia nervosa has been conclusively proven. For example, a Japanese study published by Hashimoto et al. in late 2005 identified a particular gene (a type of growth hormone secretagogue receptor, GHSR) that occurred much more often in patients with bulimia nervosa than in the study’s control group of individuals without an eating disorder or in the study’s other two groups’ individuals with other types of eating disorders. The researchers concluded that this gene was a risk factor for bulimia nervosa but not for the other eating disorders. These findings require confirmation by additional studies. Other studies from Japan and Europe published in 2005 suggested brain-derived neurotrophic factor (BDNF) as a susceptibility gene for eating disorders, and researchers have found lower-than-usual levels of BDNF in patients with bulimia nervosa.

Several recent literature reviews have suggested a correlation between childhood abuse (physical, sexual, or emotional) and bulimia nervosa or other eating disorders. Trottier and MacDonald (2017) proposed that the trauma of childhood abuse, particularly emotional and sexual abuse, could inhibit a person’s impulse control and ability to control one’s emotions, and development of eating disordered behaviors could be an attempt to cope with negative emotions and beliefs developed as a result of the abuse. Further research is needed to develop these theories.

Although eating disorders in the military population are not widely studied, a recent review concluded that the stressors of military life, including combat exposure, strict weight and fitness requirements, and military sexual abuse might increase the risk of developing bulimia nervosa or another eating disorder (Bartlett and Mitchell, 2015).

Traits common to people with bulimia nervosa have led researchers to identify certain risk factors (listed below) for developing the disorder. Issues about body shape and size can arise especially during physical developmental phases when bodies change rapidly. For example, girls who enter puberty early may be uncomfortable about changes in their body size and shape because of rapid weight gain and sexual maturation that occur sooner than their peers. Women in middle age approaching menopause may also experience body shape changes, along with changes in family and social roles as children grow into adulthood and leave home. Major life role and body changes can lead to stress. Such stresses may contribute to development of bulimia nervosa in people with additional risk factors for the disorder.

What are the signs and symptoms of bulimia nervosa?

Bulimia nervosa’s signs and symptoms usually consist of a blend of mental and physical characteristics and traits, as well as behaviors. Some may be obvious only to a medical professional; others may be more easily noticed by the affected person’s friends, family, coaches, or teachers (if the individual is in school). See the Checklist: Signs and symptoms family and friends may be likely to notice and Checklist: Signs and symptoms dentists and primary care professionals may be likely to notice. Other less common symptoms may be present as well.

Binge eating and purging may seem like obvious signs that are hard to miss. However, these behaviors can be, and often are, well masked by a person with bulimia nervosa. People with bulimia nervosa may hide the behavior because they feel shame and guilt. The disorder may progress for some time before anyone else notices because the weight or outward physical appearance of people with bulimia nervosa may not change in the same way that appearance changes with an eating disorder like anorexia nervosa. Even an individual with a severe case of bulimia nervosa can appear to be of normal weight or even overweight. That is why weight is not used as a criterion in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) for diagnosing bulimia nervosa.

What family and friends may be likely to notice

People with bulimia nervosa may behave around food in ways that stand out from how most people behave around food. They might skip meals, rapidly change food likes and dislikes, avoid social outings that involve consuming food with others, or make excuses not to eat. People with bulimia nervosa may drink lots of water and diet soda or cut food into small bites and chew each bite excessively. Doing these things is believed to make vomiting easier. They may also be excessively impulsive, depressed, anxious, or socially isolate themselves by choice from peers, friends, and family.

Purging behavior often is not obvious because the affected person may strive to hide it. Even roommates or spouses of people with bulimia nervosa can be totally unaware of purging behaviors for years because the affected person is extremely effective at hiding the behavior. For example, a person with bulimia nervosa may run water while in the bathroom to obscure vomiting sounds or may use mouthwash, gum, and mints frequently or excuse herself or himself from meals.

Family and friends may notice the nonpurging behavior of excessive exercise, but if the individual is a bulimic athlete, drawing the line between training and excess exercise is hard. Fasting may be less obvious if the person makes reasonable excuses for not eating in certain situations.

How is bulimia nervosa diagnosed?

A medical or mental health professional who is experienced in recognizing the signs and symptoms of eating disorders can usually make a diagnosis after interviewing a patient and performing a physical examination. Often, a dentist, pediatrician, therapist, or family physician—the doctors who see the patient most often—are the first healthcare professionals with the opportunity to recognize the signs and symptoms of bulimia nervosa. The patient may not willingly describe symptoms and may be unwilling to acknowledge the observations made by a dentist or family doctor. The key to making a diagnosis is that the dentist, physician, nurse, or other healthcare professional seeing the patient has to be aware of the signs and symptoms of bulimia nervosa to recognize a possible case when they see it. They should then refer to the Diagnostic and Statistical Manual of Mental Disorders-Fifth Edition (DSM-5) to determine whether the signs and symptoms they observed fit the criteria.

Since the disorder was first being described in 1979, the criteria used to make an “official” diagnosis of bulimia nervosa have changed several times. These changes reflect ongoing debate among medical and psychological professionals over the criteria that define the disorder. Early definitions focused on binge eating and the purging/nonpurging activity, “irresistible urges to overeat,” and a “morbid fear of becoming fat.” Later definitions defined binge eating and purging/nonpurging more specifically in terms of numbers of episodes within a time frame, and added some psychiatric components. These criteria are also used to define remission and recovery from the disorder.

According to the DSM-5, the diagnostic criteria that must be met before a clinician diagnosis bulimia nervosa require that the person must have binged and engaged in purging or nonpurging compensatory behavior at least once weekly for three months and evaluate (i.e., judge) oneself according to body size and shape. Further, the behaviors must not occur exclusively during an episode of anorexia nervosa.

In December 2017, the British Medical Journal, which is a leading medical journal worldwide, published a helpful visual summary of the initial diagnosis process for a person who might have an eating disorder: The BMJ Visual Summary: Eating Disorders Initial Assessment in Primary Care . It is a free download.

Can a person with a bulimia nervosa diagnosis also experience another mental health disorder at the same time?

Yes. It is common for one or more other mental disorder such as depressive disorders, anxiety disorders, bipolar disorder, post-traumatic stress disorder or obsessive-compulsive disorder to be present with an eating disorder. This is called “comorbidity” or “co-occurring disorders.” In fact, a person may already be in treatment for another condition when the eating disorder is recognized. Depressive disorders in particular, often related to low self-esteem or poor body image, are frequently seen in individuals with bulimia nervosa. In some people, both disorders can begin around the same time, and the symptoms of the other disorder will mask the eating disorder, making it harder to diagnose. For example, avoiding family social events may be seen as social anxiety or phobia rather than the desire to avoid eating in public or being exposed to “undesirable” foods.

Can a person with a bulimia nervosa diagnosis also develop a different eating disorder? 

Unfortunately, yes. Since some of the symptoms of eating disorders are similar, diagnoses can fluctuate over time. For example, individuals given a diagnosis of anorexia nervosa, binge-eating purging type, exhibit some of the same behaviors as individuals with bulimia nervosa. The difference between the two is that the binge eating and/or purging occur only during an anorexic episode, and the criteria for a diagnosis of anorexia includes significantly low body weight, whereas most people with bulimia nervosa can maintain their body weight at a normal or only slightly lower level. If the anorexic individual’s weight rises to a normal level and he/she no longer meets the criteria for anorexia nervosa, but are still bingeing and purging, he/she may be given a new diagnosis of bulimia nervosa based on those symptoms. It is also possible to have received a diagnosis of one eating disorder as a youth and another later in life, again based on specific criteria at the time of diagnosis. The DSM-5 discusses criteria for all eating disorders.

Bulimia nervosa may also evolve into Other Specified Feeding or Eating Disorder (previously categorized as “eating disorder not-otherwise specified” in the DSM-IV) if symptoms occur infrequently after treatment and only some of the criteria for bulimia nervosa are met. Few people with bulimia nervosa develop anorexia, although this does occur. A slang term for this condition is “bulimarexia.”