CHAPTER 64

Eating Disorders

Monica Sifuentes, MD

Basic characteristics of eating disorders are summarized in Box 64.1. For more stringent criteria, refer to Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria. An adolescent may have an atypical presentation, a history of anorexia nervosa (AN) and bulimia nervosa (BN), or an underlying affective component that confuses the issue. The adolescent may not display a blatant refusal to eat but may instead exhibit subtle characteristics of disordered eating, such as constant dieting, obsession with a certain physical exercise, or irregular menstruation. Additionally, preoccupation with physical appearance and weight currently is not uncommon or necessarily pathologic in Western society. The fashion industry and social media promote the idea that thinness and beauty are interrelated. Thus, the typical adolescent who longs to be accepted by peers and who is learning to develop a sense of independence and control is a prime target for the development of disordered eating. The primary care physician is in a unique position to recognize individuals at risk, appropriately screen teenagers with specific behaviors, and provide early diagnosis of and intervention for patients with disordered eating to prevent the development of potentially lethal complications associated with these conditions. The overall goal is to decrease the lifelong medical and psychological morbidity and mortality associated with AN and BN to enhance the long-term health and emotional well-being of affected individuals.

Epidemiology

Historically, eating disorders predominately affected white adolescent females in more affluent communities. Although disordered eating currently occurs in many other settings, historically, AN and BN were rare among persons of lower socioeconomic status, among ethnic/racial minorities, and in children younger than 12 years of age. Currently, these conditions are diagnosed in individuals of all ethnic, cultural, and socioeconomic backgrounds in the United States as well as in other developed countries. Additionally, males make up an estimated 5% to 10% of all patients with eating disorders and tend to be younger, malnourished, or medically unstable when they present for treatment, which is suggestive of delayed evaluation and diagnosis.

Although dieting behavior among adolescents and young adults is not uncommon, true AN has a prevalence of approximately 0.5% to 1% in these individuals. Estimates have ranged from 1% to 10% in high-risk groups, such as upper- and middle-class white females. Less than 5% of these cases are males, with a female-to-male ratio of 9:1, although this prevalence has been disputed to be an under-estimate of young males with AN. The age of onset historically was reported to occur during middle adolescence (age 14–16 years). It has become increasingly more common, however, for school-age children and younger teenagers to be dissatisfied with their weight and concerned with body image. Studies of middle-income elementary school girls have reported significant body and weight dissatisfaction. Skipping meals and desserts, fasting, and vomiting all have been reported specifically to lose weight. For many of these young girls, the goal is not to maintain a normal weight but to be under-weight by standard growth charts.

Derived from Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition.

The prevalence of BN is approximately 1% to 4%, although some studies report that as many as 8% of adolescent and college women and 0.5% of men have bulimia. The age of onset of BN tends to be later than for AN, with symptoms beginning during late adolescence and young adulthood (age 17–20 years). Several behavioral and affective disorders have been associated with the development of AN and BN. These include comorbid psychiatric conditions, such as depressive, bipolar, and anxiety disorders; alcoholism and substance use; other addictive behaviors (eg, laxative abuse); poor impulse control; and obsessive-compulsive personality. Girls who are obese or experience early puberty also are at increased risk for developing an eating disorder, with symptoms starting in the context of dieting. A history of sexual abuse may be present among patients with eating disorders. Additionally, suicidal behavior (ie, attempts) is more likely in individuals with BN, as are reports of an increased incidence of family members with substance use and dependence disorders. Generally, eating disorders occur with increased frequency in patients with a family history of eating and mood disorders as well as obesity.

Variants of eating disorders, which do not meet full diagnostic criteria based on previous guidelines but cause significant distress and impairment in social, occupational, or other important areas of functioning, are not uncommon in preteens and adolescents. Exact numbers are uncertain because many of these patients remain “under the radar” and the consequences of their eating behaviors are not fully recognized. Additionally, more than one-half of junior high and high school girls have dieted at some time, many of them repeatedly. For this reason, the revised DSM-5 criteria for both AN and BN are less restrictive. New diagnostic categories now include the spectrum of patient behaviors: avoidant/restrictive food intake disorder, atypical AN, and binge-eating disorder.

Clinical Presentation

The patient with eating disorder may present with general symptoms related to weight loss and nutritional or volume deficiencies, such as fatigue or syncope. Such a patient also may exhibit minimal weight gain according to standard growth charts or a delay in the onset of puberty or progression of pubertal development. More importantly, female adolescents also may present with primary or secondary amenorrhea noted incidentally during an annual health maintenance or sports physical examination. Sometimes an underlying psychiatric condition, such as obsessive-compulsive disorder or anxiety, is the impetus for the medical referral. Occasionally, a patient with undiagnosed eating disorder is hospitalized because of complications related to the condition, such as electrolyte disturbances associated with diuretic use, hematemesis from induced vomiting, or syncope from hypovolemia. Finally, the preteen or adolescent may be referred to the primary care physician by a concerned parent, well-intentioned friend, informed coach, or astute school personnel who notice significant weight loss or restrictive eating patterns.

Pathophysiology

Anorexia Nervosa

Although several risk factors predispose an individual to the development of AN, this condition, like other eating disorders, has no single cause (Box 64.2). Longitudinal studies clearly point to a significant role for inappropriate dieting behavior in the pathogenesis of an eating disorder. Because not all dieters develop an eating disorder, however, other contributing risk factors must be involved. Current theory suggests that the etiology of AN is multifactorial and precipitated by a complex interaction between genetic, environmental/cultural, and psychological risk factors, along with the adolescent’s personal experiences and individual personality traits.

Biologic Factors

It has been postulated that the normal increase in adipose tissue with the onset of puberty creates special challenges for some girls. An eating disorder may develop as an attempt to control or combat this normal pubertal weight gain with the initiation of dieting behavior. Preexisting hypothalamic dysfunction also has been implicated as a contributing factor to AN. Additionally, changes in neurotransmitter levels have been shown to occur with initial vomiting or dieting. These changes may result in specific psychiatric symptoms that may perpetuate disordered eating. Recent data obtained with neuroimaging studies have shown that most of the physiological disturbances resolve with normalization of the patient’s body weight, however. Additionally, a premorbid disturbance in the neurotransmitter serotonin has been speculated to be a risk factor for the development of AN and BN. Serotonin controls appetite by creating a sensation of fullness or satiety. It is also known to affect sexual and social behavior, mood, and stress responses. Although further studies are needed to confirm the exact role of this hormone in the development of an eating disorder, it has been shown that decreases in this brain neurotransmitter have been associated with impulsivity, aggression, and depression.

Adapted from Rome ES, Ammerman S, Rosen DS, et al. Children and adolescents with eating disorders: the state of the art. Pediatrics. 2003;111(1):e98–e108.

Leptin, a circulating hormone produced in adipose tissue, also seems to have a significant role in mediating the neuroendocrine effects of AN. Decreased concentrations of leptin are seen with reduced body fat stores as a result of decreased caloric intake and energy deficits. Paradoxically, leptin levels also appear to contribute to physical hyperactivity (eg, compulsive exercise, restlessness), which is often seen in patients with AN despite their inadequate metabolic intake.

Genetic Factors

A genetic predisposition to anorexia has been shown in studies of monozygotic twins. The incidence of the disorder is increased in sisters and other female relatives of patients with AN.

Personal Characteristics

Generally, patients with AN are described as obsessive-compulsive personality types, perfectionists, and overachievers, particularly in academics and sports. They also display low self-esteem and high anxiety levels despite their perceived successes by others. In the case of girls, they are the “model daughters” who have never caused any previous problems because of their compliant, self-sacrificing, duti-ful, nonassertive nature.

An increased association exists between AN and major depression, and many studies of women have shown that first-degree relatives of patients with AN have higher rates of depression than the general population. Many depressive symptoms in patients with AN improve with restoration of body weight, however. Therefore, some of these clinical features of depression also may be secondary to the adolescent’s state of severe malnutrition or starvation.

Familial Influences

Researchers have noted that certain family dynamics may serve to initiate and perpetuate AN, although it is no longer believed that family dysfunction is the main cause of disordered eating. Typically, however, the family is overprotective and rigid, with the mother often enmeshed in her daughter’s life. Conflict resolution tends to be poor, and an inability to express feelings within the family is often evident. Diagnosis of an eating disorder often causes additional stress in the family, thus contributing to more difficulties in their relationships. Multiple case-control studies have shown an increased rate of AN and BN in relatives of patients with eating disorders. This may be the result of inheritance patterns of personality traits as well as comorbid mood and anxiety disorders. Although there is limited research, studies suggest that there is no difference in familial or genetic factors between males and females with eating disorders.

Social/Environmental Pressures

The media as well as postindustrial, high-income societal standards are believed to play a role in setting the stage for the development of eating disorder. Individuals in affluent communities are especially at risk if thinness, food, eating, and obsessive exercise become the prime focus of daily activity. In addition, young women become caught in what has been labeled a “slender trap,” in which thinness is equivalent to attractiveness and success. Food restriction or purging is a means of attaining thinness. An inability to maintain thinness equals failure. Role models in the media, such as fashion models and actors, also serve as ideals by which young people create their physical standards.

Other Influences

Involvement in particular extracurricular activities that promote leanness and endurance, such as ballet, gymnastics, figure skating, cheerleading, and running, may contribute to the development of AN in females. For male athletes, such influences include participation in sports such as wrestling, lightweight rowing, pole vaulting, and long-distance running, in which maintaining a low weight is important and dieting and/or fasting is used to achieve that weight limit. Chronic medical conditions, such as diabetes mellitus or inflammatory bowel disease (IBD), also may contribute to the development of an eating disorder.

Bulimia Nervosa

Several theories have been proposed to explain the etiology of BN but, similar to AN, no single etiology has been confirmed. Most likely, multiple factors contribute to the development of this eating disorder, and it is the complex interaction between these factors at a particular developmental point in an older adolescent’s life that results in this condition.

Biologic, psychological, familial, and societal influences are thought to contribute to the development of BN in older teenagers and young adults. Among other issues, adolescent and parental obesity are risk factors for BN, as are early menarche, early sexual experiences, posttraumatic stress disorder, and a history of childhood sexual or physical abuse that occurs in conjunction with a comorbid psychiatric condition. More important, dieting has been documented as an important risk factor in this age group.

Familial dysfunction and high levels of conflict also have been associated with BN. Unlike with AN, conflict might be discussed openly but negatively within the family, and the existence of inadequate expression of emotions may result in a lack of parental warmth and concern. As a result, the relationship between the parent and teenager is distant rather than enmeshed. The adolescent generally has a low level of self-esteem, high impulsivity, perfectionist temperament, and body image dissatisfaction. Additionally, parents and relatives have a high rate of affective and eating disorders as well as alcoholism.

Differential Diagnosis

It is important to differentiate AN from BN, although occasionally this distinction may be difficult to make if a patient displays behaviors consistent with both conditions. Additionally, approximately 50% to 60% of patients with eating disorders have associated comorbid psychiatric disorders. Major affective disorders to consider include depression, bipolar disorder, and obsessive-compulsive disorder. Anxiety disorders and substance use also are commonly seen, although the latter is more strongly associated with BN.

Weight loss, loss of appetite, and refusal to eat can be associated with many medical conditions. Therefore, other diagnoses to consider when evaluating patients for AN include IBD, malabsorption, celiac disease, diabetes mellitus, occult malignancies, AIDS, Addison disease, hyperthyroidism or hypothyroidism, hypopituitarism, tumors of the central nervous system, and chronic substance use, particularly with amphetamines and cocaine. Superior mesenteric artery syndrome is another important condition to consider in the differential diagnosis; however, it also can be a consequence of an eating disorder, specifically AN.

Evaluation

History

A complete medical history, including a detailed review of systems, should be obtained from all adolescents and young adults with suspected eating disorder to rule out the multiple other conditions in the differential diagnosis of decreased appetite and weight loss. The primary care physician then should interview the patient alone and focus on establishing the diagnosis of disordered eating by addressing more specific issues related to changes in food preferences (eg, vegetarian, vegan, low-fat diet), eating behaviors, dieting, calorie counting, weight history, exercise routine, and body image concerns (Box 64.3). The 2008 article titled “Interviewing the Adolescent With an Eating Disorder” includes a detailed discussion of interviewing techniques to use on patients with a suspected eating disorder. The severity of the medical and nutritional aspects of the condition should be determined, after which a thorough psychosocial evaluation should be conducted. Inquiries should focus on symptoms associated with complications of eating disorders, such as dysphagia secondary to esophagitis from recurrent vomiting, constipation from fluid restriction, and muscle weakness associated with emetine toxicity from chronic ipecac use. Because ipecac is no longer readily available, this adverse effect is seen less frequently than in the past. Although rarely seen by the primary care physician at the initial visit when the diagnosis of an eating disorder is made, recognition of serious medical complications is paramount to determining the type and urgency of further care.

Stay updated, free articles. Join our Telegram channel

Join