Eating disorders are common, particularly among women. Up to 3% of American women meet diagnostic criteria for an eating disorder, and up to 20% of college-aged women engage in some form of binging and purging behavior. Anorexia nervosa and bulimia nervosa are the best-known eating disorders; others included in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), are avoidant/restrictive food intake disorder, binge eating disorder, unspecified feeding and eating disorders, pica, and rumination disorder.
Anorexia nervosa is characterized by restricted food intake leading to low body weight, fear of gaining weight, and a distorted body image. About half of patients develop concurrent bulimic symptoms, and amenorrhea is common.
Bulimia nervosa is characterized by recurrent episodes of binge eating and inappropriate compensatory behaviors intended to prevent weight gain or cause weight loss, such as self-induced vomiting or laxative abuse. Body weight is usually normal, and patients often have dry skin, low blood pressure, and increased heart rate.
Binge eating disorder is characterized by recurrent episodes of binge eating without inappropriate compensatory behaviors. Episodes are accompanied by a sense of loss of control overeating.Unspecified feeding or eating disorders may include atypical anorexia nervosa, bulimia nervosa of low frequency, binge eating of low frequency, purging disorder, or night eating syndrome.
The etiology of eating disorders is likely multifactorial, with genetic, psychological, environmental, and social factors implicated. Some clinicians have speculated that a cultural preoccupation with thinness and dieting in the US and other Western countries has set the stage for eating disorders. Equally plausible is the possibility that the increasing prevalence of overweight and obesity in the US and other countries has triggered an unhealthy response to weight problems (i.e., binging, purging, and restricting). Up to 40% of adolescent girls in the US believe they are overweight, and approximately 60% are attempting to lose weight. A substantial number of these girls have reported that they tried vomiting or laxatives to control their weight.
Significant morbidity and mortality are associated with severe or long-standing eating disorders, including osteoporosis, decreased gray matter, electrolyte and metabolic abnormalities, heart disorders including arrhythmias caused by electrolyte imbalances, gastrointestinal dysfunction, dental erosion, and infertility. Osteoporosis, decreased gray matter, and dental erosion are often not reversible, even with appropriate treatment and weight recovery. Comorbid psychiatric disorders, including depression, anxiety, and obsessive-compulsive disorder, are present in more than half of patients.
About 90% of eating disorder cases occur in women, with onset typically occurring in late adolescence and early adulthood. Additional risk factors include:
History of obesity and/or dieting. A history of obesity is linked to increased risk for eating disorders. Adolescents who reported dieting during mid-adolescence were significantly more likely to develop eating disorders.
Participation in activities that emphasize leanness. Examples include ballet, gymnastics, running, and wrestling.
Family history. Women who have a first-degree relative with an eating disorder are up to 10 times more likely to develop an eating disorder themselves. Eating disorders are also associated with a family history of depression.
Psychiatric history. Histories that include depression, substance abuse, sexual abuse, weight dissatisfaction, and low self-esteem are linked to higher risk for eating disorders.
Early puberty. Early sexual development may lead to increased self-consciousness regarding body image and is associated with subsequent dieting behaviors.
The American Psychiatric Association’s diagnostic criteria (DSM-5) for anorexia nervosa are summarized as follows:
- Restriction of energy intake relative to requirements, leading to a significantly low body weight in the context of age, sex, developmental trajectory, and physical health. Significantly low weight is defined as a weight that is less than minimally normal or, for children and adolescents, less than that minimally expected.
- Intense fear of gaining weight or of becoming fat or persistent behavior that interferes with weight gain, even though at a significantly low weight.
- Disturbance in the way in which one’s body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or persistent lack of recognition of the seriousness of the current low body weight.
The condition is subclassified as either the restricting type or the binge eating/purging type, depending on whether the individual regularly engages in binge eating or purging behavior (e.g., self-induced vomiting or the misuse of laxatives, diuretics, or enemas).
The DSM-5 criteria for bulimia nervosa are summarized below:
- Recurrent episodes of binge eating. An episode of binge eating is characterized by both of the following:
- A. Eating, in a discrete period of time (e.g., within any 2-hour period), an amount of food that is definitely larger than most people would eat during a similar period of time and under similar circumstances.
- B. A sense of lack of control overeating during the episode (e.g., a feeling that one cannot stop eating or control what or how much one is eating).
- Recurrent inappropriate compensatory behavior to prevent weight gain, such as self-induced vomiting; misuse of laxatives, diuretics, enemas, or other medications; fasting; or excessive exercise.
- The binge eating and inappropriate compensatory behaviors both occur, on average, at least once 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.
Several screening questionnaires are available for primary care clinicians. For example, in the questionnaire below (SCOFF), developed at St. George’s Hospital Medical School in London in 1999, positive responses to 2 or more questions indicated a probable diagnosis of eating disorder, with a sensitivity and specificity of 78% and 88%, respectively., Like the well-known CAGE questionnaire for alcohol misuse, the name SCOFF comes from key words within the 5 questions.
- Do you make yourself sick because you feel uncomfortably full?
- Do you worry you have lost control over how much you eat?
- Have you recently lost more than 14 pounds (one stone) in a 3-month period?
- Do you believe yourself to be fat when others say you are too thin?
- Would you say that food dominates your life?
Initial laboratory studies should include a complete blood count, electrolytes, calcium, magnesium, phosphorous, blood urea nitrogen, creatinine, urinalysis, and thyroid function tests. A baseline electrocardiogram and pregnancy testing are indicated in all women with amenorrhea. Bone-density testing and MRI of the brain may be indicated if osteoporosis or impaired cognition is suspected.
Medical comorbidities, including electrolyte disturbances and dehydration, should be treated and, when possible, prevented. Treatment varies depending on severity of illness and concurrent psychiatric issues.
Hospitalization is indicated for severe malnutrition (body weight less than 75% of ideal), suicidal ideation, electrolyte disturbances, dehydration, abnormal vital signs (e.g., bradycardia, hypothermia), cardiac arrhythmias, and failure of outpatient treatment.
Vitamin and mineral supplementation may be necessary. An inpatient or outpatient structured eating program may help restore healthy eating habits.
Psychotherapy is a mainstay of treatment for certain eating disorders. Because drug therapy is, for the most part, ineffective for anorexia nervosa, psychotherapy is often the treatment of choice. However, not all forms of therapy have undergone rigorous testing. Family-based therapy appears to be more effective in anorexic adolescents (but not adults) than other therapeutic modalities. In adults, psychotherapy has been found to reduce anorexic behaviors in up to 60% of patients. However, more stringent assessment of the effects of cognitive-behavioral therapy indicated that only 17% of patients treated with this modality could be considered fully recovered. Olanzapine, an antipsychotic medication, might be helpful in restoring weight in acutely ill patients.
In persons with binge eating disorder, a disorder characterized by excessive bingeing without compensatory behavior, cognitive-behavioral therapy and interpersonal therapy reduced binge eating by 48-98% and produced abstinence rates of about 60%., Medications such as antidepressants and anticonvulsants may also play a role. Lisdexamfetamine, a stimulant medication initially developed for the treatment of ADHD, has been shown to be effective in binge eating disorder.
Most studies show cognitive-behavioral therapy to be more effective than drug therapy for persons with bulimia nervosa. Combining medication with psychotherapy improves overall treatment effectiveness. Fluoxetine, a selective serotonin reuptake inhibitor (SSRI), is considered to be first-line pharmacotherapy for bulimia. A different SSRI (e.g., citalopram, sertraline) might be used as second-line treatment and some tricyclic antidepressants (e.g., desipramine, imipramine) might also be used as third-line treatments. Also, self-help manuals appear to be as effective as psychotherapy in reducing binge episodes for some patients.
Group support in a structured setting is a useful intervention. Groups based on principles of cognitive-behavioral or dialectic behavioral therapy have been shown to be effective. Twelve-step programs such as Overeaters Anonymous are often effective as well.
Nutrition therapy is indicated for patients with eating disorders, including anorexia nervosa, bulimia nervosa, and binge eating disorder. The degree to which nutrition professionals should be involved depends on the seriousness of the disorder. For instance, individuals who meet some but not all diagnostic criteria for anorexia or bulimia may not face the same mortality risk as an individual with a more clearly defined and serious eating disorder. Similarly, individuals with the “restricting” subtype of anorexia who are significantly below ideal body weight and have disordered electrolyte concentrations are at greater risk of life-threatening arrhythmias compared with anorexic individuals who present with the bingeing/purging subtype.
Refeeding: Particularly in persons who are significantly underweight, electrolytes should be carefully monitored and refeeding introduced gradually and progressively. Hypokalemia has been reported in 14% of patients with bulimia nervosa, and hyponatremia may be brought on by the use of diuretics, vomiting, and/or excessive water intake. Patients often ingest excessive water to curb hunger or provide the false impression of weight stability during weight checks at medical appointments. If patients are aggressively fed and rehydrated, hypophosphatemia-induced refeeding syndrome may occur, potentially involving dysrhythmias, respiratory failure, rhabdomyolysis, seizures, coma, heart failure, weakness, hemolysis, hypotension, ileus, metabolic acidosis, and sudden death. High sodium intake increases the risk of fluid overexpansion. Limiting sodium intake to required amounts (500 mg/d) is recommended.
To further assist in preventing refeeding syndrome, supplemental phosphorus should be started early and serum levels maintained above 3.0 mg/dL. Hypomagnesemia occurs in approximately 1 in 6 patients with anorexia nervosa and may persist for weeks after refeeding. Although weight gain is an eventual goal for anorexic patients, calories should be secondary to protein during initial refeeding. Suggested guidelines include providing 1.2 grams of protein per kilogram of ideal body weight/day for the first week and no more than 20 kcal/kilogram/day during the first week to avoid refeeding syndrome.22 A reasonable weight regain goal is 0.5-1.0 pound per week.
In addition to the need for a hypercaloric diet during weight restoration, evidence suggests that individuals with anorexia nervosa require 200-400 calories per day more than matched controls in order to maintain weight.
Emotional support. It is essential to avoid power struggles over diet choices or weight gain. Individuals with eating disorders often drop out of treatment programs because eating generates profound anxiety. Aggregate results of surveys of eating-disordered patients found that they rated support, understanding, and empathic relationships as critically important. Psychological approaches were viewed as the most helpful, while medical interventions focused exclusively on weight were viewed as not helpful. Pressuring patients to make commitments to improve (e.g., to enroll in treatment or gain weight) has not been demonstrated as effective and may be counterproductive. Instruments used to assess patients’ readiness to stop restricting foods, purging, or bingeing have been found to be good predictors of clinical outcome in patients with anorexia nervosa.
Nonrestrictive vegetarian or vegan diets can be adequate. Patients who follow vegetarian diets should not be pushed to alter that preference. Many healthy people choose to avoid meat or avoid all animal-derived products, and these choices bring many health benefits. People suffering from eating disorders also often report feeling disgusted by meat. However, vegetarianism does not cause eating disorders. In one study vegetarians and vegans motivated by ethical concerns had lower eating-related pathology than semi-vegetarians or “flexitarians.” Previous research conflating vegetarianism with disordered eating often did not account for food avoidance that is normative in the context of vegetarianism. Healthful plant-based foods should be a part of eating disorder recovery.
Weight-loss treatments for patients with binge eating disorder. Studies of the effects of both dietary and behavioral approaches to weight loss show that weight-loss treatments reduce binge eating frequency. Although it was once suspected that attempts at weight loss preceded binge episodes, the structured meal plans provided for weight loss may give binge eaters a feeling of greater control over food intake. Spontaneous remission of binge eating has also been reported.
Vitamin/mineral deficiency. More than half of patients with anorexia nervosa failed to meet the recommended dietary allowance (RDA) for vitamin D, calcium, folate, vitamin B12, zinc, magnesium, and copper when assessed by diet history. Deficiencies are also commonly found for several vitamins, including thiamine, B2, niacin, B6, folate, C, E, and K.,, There have been case reports of patients with anorexia nervosa who were diagnosed with pellagra due to niacin deficiency and scurvy due to vitamin C deficiency., There are also case studies of patients with bulimia nervosa presenting with folate deficiency and coagulation abnormalities due to vitamin K deficiency., Replacement of these and other nutrients is an important part of nutrition therapy. Zinc in particular has been found to enhance the rate of recovery in anorexics by increasing weight gain and improving anxiety and depression.
Bone health. Low intakes of calcium, vitamin D, and vitamin K can reduce bone mineral density and put eating disorder patients at very high risk for osteoporosis.,, Weight gain itself reduces bone turnover in patients with anorexia nervosa. In one study, treating bone disease in anorexic patients with calcium and vitamin D supplements was as effective as etidronate for reversing osteoporosis.
Nutritional consultation with a registered dietitian trained in eating disorder recovery.
Supplementation as indicated.
Psychiatric consultation for evaluation and to arrange appropriate follow-up.
See Nutritional Requirements throughout the Life Cycle chapter.
What to Tell the Family
Eating disorders are typically precipitated and perpetuated by a combination of genetic, developmental, and psychological factors, requiring a multidisciplinary team approach (physician, psychiatrist, psychologist, and dietitian) to treatment. Anorexia nervosa is particularly difficult to treat, often necessitating repeated episodes of hospitalization to prevent extreme weight loss. Bulimia nervosa is usually not life-threatening and may respond well to cognitive-behavioral therapy, medication, or a combination of the two. Binge eating disorder often responds well to behavior modification weight-loss strategies alone. Family members can render assistance by providing regular, well-balanced meals and emotional support.
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