9.4 Eating Disorders, ARFID & Pediatric Feeding Disorder

DSM-5 Eating Disorders in Children and Adolescents

Anorexia nervosa (AN): restriction of energy intake leading to significantly low weight (in youth, this includes failure to make expected weight gain or falling off the growth curve — there is no absolute low-weight threshold), intense fear of weight gain, and body-image disturbance or lack of recognition of seriousness.

Atypical anorexia nervosa: all AN criteria are met except that weight remains within or above the normal range despite significant weight loss. It is equally dangerous — rate and magnitude of loss, not absolute weight, drive medical risk — and is a high-yield exam concept because these patients are easily missed.

Bulimia nervosa (BN): recurrent binge eating with compensatory behaviors (vomiting, laxatives, fasting, excessive exercise) at least weekly for 3 months, with self-evaluation unduly influenced by shape and weight. Binge eating disorder (BED): recurrent binges with distress but without regular compensation. Purging carries hypokalemia, hypochloremic alkalosis, parotid enlargement, and esophageal injury risk.

Medical Instability and Hospitalization

Society for Adolescent Health and Medicine (SAHM/SRHM) and AAP criteria for inpatient medical stabilization include:

Refeeding Syndrome

Refeeding syndrome occurs when carbohydrate reintroduction after prolonged restriction triggers an insulin surge that drives phosphate, potassium, and magnesium intracellularly. The hallmark is hypophosphatemia; consequences include cardiac failure, arrhythmia, respiratory failure, rhabdomyolysis, seizures, and death. Risk rises with very low weight and overly aggressive initial feeding.

Traditional practice is 'start low, go slow' (begin around 1,000–1,400 kcal/day and advance cautiously). Newer evidence supports moderately higher-calorie starts (roughly 1,400–2,000 kcal/day) in mildly to moderately malnourished adolescents provided electrolytes are monitored closely and phosphorus is supplemented proactively; the most severely malnourished (<70% median BMI) still warrant conservative starts. Give thiamine before feeding, check phosphate/potassium/magnesium at least daily early on, and replace deficits.

Nutrition Rehabilitation

Weight restoration targets: 0.5–1 kg/week inpatient and 0.25–0.5 kg/week outpatient. Because of metabolic adaptation (hypermetabolism during refeeding), prescriptions commonly must escalate in 100–200+ kcal/day increments every few days, and many adolescents ultimately need 3,000–4,000+ kcal/day to sustain gains. The dietitian titrates the plan, manages early satiety and gastroparesis symptoms, and supports variety expansion as weight normalizes.

Treatment Models

Family-based treatment (FBT; the Maudsley approach) is first-line for adolescent AN (and has evidence in adolescent BN): parents are empowered to take charge of refeeding their child at home, with the therapist and dietitian coaching the family rather than blaming it. CBT-based approaches are used for BN and BED in older adolescents. Dieting and weight-focused teasing are established risk factors — screening and early referral change prognosis.

Chronic undernutrition in AN produces growth stunting, delayed or arrested puberty, and impaired peak bone mass accrual — adolescence is the critical window for bone mineralization, and deficits may be only partially reversible even after weight restoration, so monitor bone health (calcium and vitamin D adequacy, dual-energy X-ray absorptiometry when indicated) and avoid high-impact exercise during medical instability. Amenorrhea, lanugo, bradycardia, and cold intolerance are common physical findings.

Avoidant/Restrictive Food Intake Disorder (ARFID)

ARFID is an eating or feeding disturbance causing failure to meet nutritional needs (weight loss or faltering growth, significant deficiency, enteral-dependence, or marked psychosocial interference) with no body-image disturbance — the key distinction from AN. Three characteristic presentations, often overlapping:

• Sensory sensitivity to texture, taste, or appearance
• Fear of aversive consequences (choking, vomiting, allergic reaction)
• Low interest in eating / poor appetite

ARFID differs from typical picky eating by its nutritional and functional severity. Consequences include specific deficiencies (iron, zinc, vitamin C, vitamin D) and growth failure. Treatment combines CBT-AR, feeding therapy with systematic desensitization/food chaining, and dietitian-led nutrition restoration.

Pediatric Feeding Disorder (PFD)

Pediatric feeding disorder is defined by consensus as impaired oral intake that is not age-appropriate, associated with dysfunction across four domains: medical, nutritional, feeding skill, and psychosocial. PFD typically describes skill- or medically based impairment in young children (prematurity, tube dependence, oral-motor delay), whereas ARFID is a psychiatric diagnosis; the two can co-occur. Management uses a multidisciplinary feeding team — dietitian, speech-language and occupational therapists, psychologist, gastroenterologist, and physician — that coordinates oral-motor skill building, medical optimization (treating reflux, constipation, and eosinophilic esophagitis that reinforce food refusal), and behavioral strategies such as scheduled meals, neutral exposure, and limiting grazing and liquid calories between meals. For tube-dependent children, structured tube-weaning protocols pair hunger provocation with intensive feeding therapy and close weight surveillance. Avoidant and sensory-based eating is also highly prevalent in autism spectrum disorder (see the neurodevelopmental chapter); rigidity and sensory profiles there are managed with similar graded-exposure principles. Across this entire spectrum, the dietitian anchors assessment of growth, nutrient adequacy, and safe advancement of oral intake.