Eating Disorders: Nutritional Considerations

Nutrition therapy is indicated for patients with eating disorders, including Anorexia Nervosa, Bulimia Nervosa, Binge Eating Disorder.¹¹ The degree to which nutrition professionals should be involved is, in part, a function of the seriousness of the disorder. For instance, individuals who meet some but not all diagnostic criteria for Anorexia or Bulimia¹² may not face the same mortality risk as an individuals with a more clearly defined and serious eating disorder. Similarly, individuals with the "restricting" sub-type of anorexia who are significantly below ideal body weight and have disordered electrolyte concentrations are at greater risk of life-threatening arrhythmias,¹³ compared with anorexic individuals who represent 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, congestive heart failure, weakness, hemolysis, hypotension, ileus, metabolic acidosis, and sudden death.¹⁴ High sodium intakes increase risk of fluid overexpansion.¹⁵ Limiting sodium intake to required amounts (500 mg/day) is prudent.

To further assist in preventing refeeding syndrome, supplemental phosphorus should be started early and serum levels maintained above 3.0 mg/dL.¹⁶ Hypomagnesemia has also been found in approximately 1 in 6 patients with anorexia nervosa, and may persist for weeks after refeeding.¹⁷Although weight gain is an eventual goal for anorexia 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 kcalories per kilogram/1,000 calories per day during the first week to avoid refeeding syndrome.¹⁵ A reasonable weight regain goal is 0.5 to 1.0 pound per week.¹³

In addition to the need for a hypercaloric diet during weight restoration, evidence indicates that individuals with anorexia nervosa require 200 to 400 calories per day more than matched controls in order to maintain weight.¹³

Avoiding power struggles with patients over diet choices or weight gain may be important. 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.¹³

Patients who follow vegetarian¹⁸ diets should not be pushed to alter that preference. In addition, pressuring patients to make commitments to improve (eg, 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.¹³

Weight-Loss Treatments

Weight-loss treatments are effective 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.¹⁰ 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 noted.⁸

Vitamin/Mineral Deficiency

Vitamin/mineral deficiency is a frequent finding for patients with eating disorders, requiring diagnosis and treatment. 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.¹⁹ Deficiencies are also commonly found for several vitamins, including thiamine, B₂, niacin, B₆, folate, C, E, and K.^20-22 In case reports, patients with Anorexia Nervosa have been diagnosed with pellagra due to niacin deficiency,²³ and scurvy due to vitamin C deficiency.²⁴ Case studies also report patients with Bulimia Nervosa experiencing folate deficiency²⁵ coagulation abnormality due to vitamin K deficiency.²⁶

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.²⁷ Although weight gain itself reduced bone turnover in patients with Anorexia Nervosa ,²⁸ treating bone disease in anorexia patients with calcium and vitamin D supplements was as effective as etidronate for reversing osteoporosis.²⁹

Orders

Psychiatric consultation for evaluation and to arrange outpatient follow-up.

Nutritional consultation and supplementation as indicated.

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, 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-based weight-loss strategies alone. Family members can render assistance by providing regular, well-balanced meals and emotional support.