7.3 Feeding, Eating, and Elimination Disorders

7.3 Feeding, Eating, and Elimination Disorders

Quick Answer: Feeding, eating, and elimination disorders encompass serious psychiatric disturbances that involve severe disruptions in eating behaviors, nutritional intake, and physiological self-regulation. Anorexia Nervosa is defined by energy restriction leading to significantly low body weight, intense fear of weight gain, and distorted body image (subtyped into restricting versus binge-eating/purging, with adult BMI severity tiers); Bulimia Nervosa requires recurrent binge eating with inappropriate compensatory behaviors (purging, fasting, laxatives) at least once weekly for 3 months in individuals who maintain normal or above-normal weight; Binge-Eating Disorder (BED) features recurrent binge episodes without compensatory purging; and Avoidant/Restrictive Food Intake Disorder (ARFID) involves nutritional failure without body image distortion. Elimination disorders include Enuresis (urinary incontinence, age ≥ 5) and Encopresis (fecal incontinence, age ≥ 4, commonly linked to constipation with overflow). Gold-standard psychotherapies include Family-Based Treatment (FBT / Maudsley) for adolescent anorexia and Enhanced Cognitive Behavioral Therapy (CBT-E).

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Anorexia Nervosa (AN)

Anorexia Nervosa is a potentially life-threatening disorder characterized by persistent caloric restriction, profound fear of weight gain, and significant distortions in body perception.

Diagnostic Criteria (DSM-5-TR)

To meet criteria for Anorexia Nervosa, three essential criteria must be satisfied:

1. Criterion A (Restriction of Energy Intake): Persistent 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 for adults or less than that minimally expected for children and adolescents.
2. Criterion B (Fear of Weight Gain): Intense fear of gaining weight or of becoming fat, or persistent behavior that interferes with weight gain, even though at a significantly low weight.
3. Criterion C (Body Image Disturbance): 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.

Diagnostic Evolution Note: Amenorrhea (the absence of at least three consecutive menstrual cycles) was a mandatory criterion in DSM-IV but was eliminated in DSM-5. This removal allows the inclusion of males, prepubertal females, females taking oral contraceptives, and postmenopausal females.

Subtypes of Anorexia Nervosa

• Restricting Type: During the last 3 months, the individual has not engaged in recurrent episodes of binge eating or purging behavior (i.e., self-induced vomiting or the misuse of laxatives, diuretics, or enemas). Weight loss is accomplished primarily through dieting, fasting, and/or excessive exercise.
• Binge-Eating/Purging Type: During the last 3 months, the individual has engaged in recurrent episodes of binge eating or purging behavior (i.e., self-induced vomiting or misuse of laxatives, diuretics, or enemas). Crucial Differential Rule: If an individual engages in binge eating and purging but has a significantly low body weight, the correct diagnosis is Anorexia Nervosa, Binge-Eating/Purging Type, not Bulimia Nervosa.

Severity Specifiers Based on Body Mass Index (BMI)

For adults, severity is determined strictly by current Body Mass Index (BMI) (for children and adolescents, corresponding BMI percentiles are utilized):

• Mild: BMI ≥ 17 kg/m²
• Moderate: BMI 16–16.99 kg/m²
• Severe: BMI 15–15.99 kg/m²
• Extreme: BMI < 15 kg/m²

Medical Complications and Physical Findings

Anorexia Nervosa has the highest mortality rate of any psychiatric illness (outside of opioid overdose), stemming from cardiac arrest and suicide:

• Cardiovascular: Sinus bradycardia (heart rate < 50 bpm), orthostatic hypotension, cardiac arrhythmias, prolonged QTc intervals, pericardial effusion, and myocardial atrophy.
• Endocrine / Metabolic: Hypothalamic-pituitary-gonadal axis suppression (causing amenorrhea and low testosterone), euthyroid sick syndrome, hypercortisolemia, hypothermia, and cold intolerance.
• Dermatological: Lanugo (fine, downy body hair growth on the face, back, and arms acting as an evolutionary thermal defense), xerosis (dry, scaly skin), brittle hair and nails, and carotenoderma (yellow-orange skin discoloration due to impaired liver metabolism of carotene).
• Skeletal: Severe osteopenia and osteoporosis resulting from chronic estrogen deficiency and elevated cortisol; bone loss is often permanent and irreversible.
• Hematological: Leukopenia (neutropenia), normocytic normochromic anemia, thrombocytopenia (pancytopenia resulting from bone marrow starvation gelatinous transformation).

Refeeding Syndrome: A Critical Medical Emergency

Refeeding syndrome is a life-threatening physiological complication that occurs when aggressive nutritional rehabilitation is introduced to a severely malnourished individual:

• Pathophysiological Mechanism: Prolonged starvation induces a catabolic state reliant on fat and protein metabolism. When carbohydrates are reintroduced rapidly, the pancreas surges insulin secretion. Insulin stimulates cellular uptake of glucose, which drives extracellular phosphorus, potassium, and magnesium into the intracellular compartment.
• Severe Hypophosphatemia: The rapid depletion of circulating serum phosphate (hypophosphatemia) cripples cellular adenosine triphosphate (ATP) production, precipitating acute congestive heart failure, lethal cardiac arrhythmias, respiratory arrest (diaphragmatic weakness), generalized seizures, delirium, rhabdomyolysis, and sudden death.
• Clinical Prevention Protocol: Nutritional rehabilitation in moderate-to-severe anorexia must begin with low caloric intake (e.g., 1,200–1,500 kcal/day), titrated upward gradually while continuously monitoring serum electrolytes (especially phosphorus, potassium, and magnesium) daily for the first two weeks.

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Bulimia Nervosa (BN)

Bulimia Nervosa is characterized by recurrent, uninhibited episodes of binge eating followed by inappropriate compensatory behaviors designed to prevent weight gain.

Diagnostic Criteria (DSM-5-TR)

1. Criterion A (Binge Eating Episodes): Recurrent episodes of binge eating, characterized by both:
   • Eating, in a discrete period of time (e.g., within any 2-hour period), an amount of food that is definitely larger than what most individuals would eat in a similar period under similar circumstances.
   • A sense of lack of control over eating during the episode (e.g., feeling unable to stop eating or control what or how much one is eating).
2. Criterion B (Compensatory Behaviors): Recurrent inappropriate compensatory behaviors to prevent weight gain, including:
   • Self-induced vomiting (most common purging method).
   • Misuse of laxatives, diuretics, enemas, or other medications.
   • Fasting or excessive, compulsive exercise.
3. Criterion C (Frequency and Duration): Binge eating and compensatory behaviors both occur, on average, at least once a week for 3 months.
4. Criterion D (Self-Evaluation): Self-evaluation is unduly influenced by body shape and weight.
5. Criterion E (Exclusion): The disturbance does not occur exclusively during episodes of Anorexia Nervosa.

Physical Profile and Clinical Hallmarks

Unlike clients with anorexia, individuals with Bulimia Nervosa typically present with normal weight or slightly overweight profiles (BMI between 18.5 and 29.9 kg/m²), which often conceals their severe pathology:

• Russell's Sign: Calluses, abrasions, or hyperkeratosis on the dorsum of the hand or knuckles caused by repeated trauma from the incisor teeth during self-induced manual gag reflex stimulation.
• Dental Erosion (Perimylolysis): Irreversible chemical erosion of dental enamel, predominantly on the lingual surfaces of the upper front teeth, caused by frequent exposure to acidic gastric hydrochloric acid (pH ~1.5–2.0).
• Parotid Gland Enlargement (Sialadenosis): Bilateral, non-inflammatory hypertrophy of the parotid and salivary glands ("chipmunk cheek" appearance) resulting from autonomic overstimulation during recurrent vomiting episodes.
• Electrolyte and Acid-Base Abnormalities:
  • Frequent purging causes hypokalemia (low potassium), hypochloremia (low chloride), and metabolic alkalosis (due to hydrogen ion loss from gastric acid). Hypokalemia carries severe risk of fatal cardiac arrhythmias.
  • Conversely, chronic stimulant laxative abuse leads to profound dehydration, hypokalemia, and metabolic acidosis (due to bicarbonate loss in watery diarrhea).
• Gastrointestinal Complications: Esophagitis, gastroesophageal reflux disease (GERD), Mallory-Weiss tears (linear mucosal tears at the gastroesophageal junction with bright red hematemesis), and, rarely, catastrophic gastric or esophageal rupture (Boerhaave's syndrome).

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Binge-Eating Disorder (BED)

Binge-Eating Disorder (BED) was elevated from a provisional category in the DSM-IV appendix to a formal standalone diagnosis in DSM-5:

Diagnostic Criteria (DSM-5-TR)

• Core Feature: Recurrent episodes of binge eating (eating a large amount in a discrete period with a sense of lack of control) occurring, on average, at least once a week for 3 months.
• Behavioral Indicators: Binge episodes must be associated with at least 3 of the following 5 characteristics:
  1. Eating much more rapidly than normal.
  2. Eating until feeling uncomfortably full.
  3. Eating large amounts of food when not feeling physically hungry.
  4. Eating alone because of feeling embarrassed by how much one is eating.
  5. Feeling disgusted with oneself, depressed, or very guilty afterward.
• Psychological Distress: Marked distress regarding binge eating is present.
• Critical Diagnostic Distinctions:
  • Binge-eating episodes are NOT associated with the recurrent use of inappropriate compensatory behaviors (no purging, laxatives, fasting, or compensatory exercise).
  • Does not occur exclusively during the course of Anorexia Nervosa or Bulimia Nervosa.

Epidemiology & Pharmacotherapy: BED is the most prevalent eating disorder in the United States and has a significantly more balanced gender distribution than anorexia or bulimia (~40% male). Pharmacotherapy includes Lisdexamfetamine (Vyvanse)—the first FDA-approved medication for moderate-to-severe BED—and selective serotonin reuptake inhibitors (SSRIs).

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Avoidant/Restrictive Food Intake Disorder (ARFID) & Other Feeding Disorders

Avoidant/Restrictive Food Intake Disorder (ARFID)

ARFID replaced and expanded the DSM-IV diagnosis of "Feeding Disorder of Infancy or Early Childhood." It involves an eating or feeding disturbance (e.g., apparent lack of interest in eating or food; avoidance based on the sensory characteristics of food; concern about aversive consequences of eating) manifested by persistent failure to meet appropriate nutritional and/or energy needs associated with one (or more) of the following:

1. Significant weight loss (or failure to achieve expected weight gain or faltering growth in children).
2. Significant nutritional deficiency (e.g., scurvy, iron-deficiency anemia).
3. Dependence on enteral feeding (nasogastric/gastrostomy tubes) or oral nutritional supplements.
4. Marked interference with psychosocial functioning.

Differential Hallmark: ARFID is differentiated from Anorexia Nervosa by the complete absence of body image disturbance, fear of gaining weight, or drive for thinness. Common presentations include children on the autism spectrum with extreme sensory food aversions (food refusal based on color, texture, or smell), or individuals with phobic avoidance following a traumatic choking or vomiting episode.

Pica

• Criteria: Persistent eating of nonnutritive, nonfood substances (e.g., paper, clay, soil, chalk, hair, soap, paint chips, string, cloth, ice [pagophagia]) over a period of at least 1 month.
• Developmental Threshold: Chronological age must be at least 2 years (mouthing nonfood objects is developmentally normal in infants under 24 months).
• Exclusions: The behavior must not be part of a culturally supported or socially normative practice (e.g., geophagy in certain West African or rural southern U.S. cultures) and must be severe enough to warrant clinical attention.

Rumination Disorder

• Criteria: Repeated regurgitation of food over a period of at least 1 month. Regurgitated food may be re-chewed, re-swallowed, or spit out.
• Phenomenology: Regurgitation is effortless, voluntary, and not accompanied by nausea, retching, disgust, or an underlying gastrointestinal condition (e.g., gastroesophageal reflux, pyloric stenosis).

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Elimination Disorders: Enuresis and Encopresis

Elimination disorders involve the inappropriate voiding of urine or feces and must be evaluated against strict developmental age cutoffs:

1. Enuresis

• Diagnostic Criteria: Repeated voiding of urine into bed or clothes, whether involuntary or intentional.
• Frequency and Duration: At least twice weekly for at least 3 consecutive months, OR the presence of clinically significant distress or impairment.
• Chronological Age Cutoff: Chronological age must be at least 5 years (or equivalent developmental level).
• Subtypes:
  • Nocturnal only: Incontinence occurs only during nighttime sleep (commonly known as monosymptomatic enuresis; most common subtype).
  • Diurnal only: Incontinence occurs during waking hours.
  • Nocturnal and diurnal: Combined subtype.
• Primary vs. Secondary:
  • Primary Enuresis: The child has never established urinary continence for a continuous period of at least 6 months (typically reflects biological immaturity of vasopressin circadian release or arousal deficits).
  • Secondary Enuresis: Incontinence emerges after the child had successfully established urinary continence for at least 6 months. Secondary enuresis is strongly associated with acute psychosocial stressors (e.g., parental divorce, arrival of a new sibling, bullying, physical or sexual abuse).
• Interventions:
  • Urine Alarm Conditioning ("Bell-and-Pad"): The gold-standard, first-line evidence-based intervention with the highest long-term cure rate and lowest relapse rate. A moisture sensor triggers an auditory alarm at the first drop of urine, awakening the child to contract the pelvic floor musculature (classical conditioning linking bladder distension with sphincter contraction).
  • Pharmacotherapy: Desmopressin acetate (DDAVP—synthetic antidiuretic hormone analog) reduces nocturnal urine volume; effective for temporary relief (e.g., sleepaway camp), but carries high relapse rates upon discontinuation.

2. Encopresis

• Diagnostic Criteria: Repeated passage of feces into inappropriate places (e.g., clothing, floor), whether involuntary or intentional.
• Frequency and Duration: At least once each month for at least 3 months.
• Chronological Age Cutoff: Chronological age must be at least 4 years (or equivalent developmental level).
• Subtypes:
  • With Constipation and Overflow Incontinence: The vast majority (~85–90%) of cases. Fecal retention leads to impaction of the rectum and colon. The colon stretches, causing loss of rectal tone and desensitization to defecation urges. Liquid stool from the proximal colon involuntarily leaks around the hard fecal mass, soiling clothing. Parents frequently misunderstand this as willful defiance or diarrhea. Clinical protocol requires medical disimpaction (enemas, oral laxatives such as polyethylene glycol), followed by scheduled, relaxed toilet sitting (e.g., 5–10 minutes after every meal to utilize the gastrocolic reflex), high-fiber diet, and behavioral positive reinforcement.
  • Without Constipation and Overflow Incontinence: Feces are deposited in conspicuous places in normal consistency. Often associated with Oppositional Defiant Disorder, Conduct Disorder, or deliberate expressions of rage/protest.

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Evidence-Based Treatments for Eating Disorders

1. Family-Based Treatment (FBT / Maudsley Approach)

Family-Based Treatment, originally developed at the Maudsley Hospital in London by Christopher Dare and colleagues and manualized by James Lock and Daniel Le Grange, is the gold-standard, first-line outpatient psychotherapy for children and adolescents with Anorexia Nervosa (and adapted for adolescent Bulimia Nervosa):

• Agnostic Etiological Stance: FBT deliberately avoids searching for family pathology or blaming parents for the disorder's development; the eating disorder is viewed as an external, uninvited illness afflicting the adolescent.
• Parents as Primary Therapeutic Agents: FBT empowers parents as the capable, essential resources responsible for refeeding their child.
• Three Progressive Phases:
  • Phase 1 (Full Parental Control): The therapist focuses entirely on the severity of the illness. Parents are tasked with complete control over food choices, meal planning, preparation, and mealtime supervision, actively preventing purging or excessive exercise. A hallmark intervention is the family meal session in the clinic.
  • Phase 2 (Gradual Return of Control): Once the adolescent achieves steady weight restoration (typically > 90% of expected body weight) and meals proceed without severe struggle, parental control is systematically and gradually handed back to the adolescent.
  • Phase 3 (Adolescent Autonomy and Termination): Initiated once healthy weight is stabilized and eating behaviors normalize. Therapy shifts to exploring healthy adolescent developmental milestones, autonomy, identity, family communication, and relapse prevention.

2. Enhanced Cognitive Behavioral Therapy (CBT-E)

Developed by Christopher Fairburn, CBT-E is an evidence-based transdiagnostic psychological treatment for all eating disorders in adults and older adolescents:

• Core Target: Modifying the over-evaluation of shape and weight and its control, which represents the core cognitive psychopathology maintaining disordered eating.
• Mechanisms: Employs regular eating schedules (eating every 3–4 hours to abolish dietary restriction), collaborative weekly in-session weighing (desensitizing weight anxiety and eliminating chaotic home scale checking), behavioral experiments challenging forbidden foods, addressing shape checking and body avoidance, and restructuring perfectionism, low self-esteem, and interpersonal triggers.