Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Eating disorders in young people
Psychiatry · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Growth and circulation can fail at any weight
Syncope, an awake pulse below 40 beats/minute, hypoglycaemia, severe dehydration, major electrolyte or ECG change, hypothermia, acute food or fluid refusal, uncontrolled purging, organ dysfunction or immediate suicide risk can occur in a young person who does not appear underweight.
Action: Assess ABCDE and glucose, record age-appropriate lying and standing observations, temperature, hydration, weight and height trajectory, obtain ECG and urgent bloods, and contact senior paediatric or medical and specialist eating-disorder clinicians. Admit for stabilisation and monitored nutrition when risk cannot be managed safely outside hospital; do not await a target BMI or routine CAMHS appointment.
Overview
Recognise restrictive, binge-purge and avoidant eating disorders throughout development, assess growth and all-domain MEED risk without a weight gate, provide family-inclusive specialist treatment, and manage medical instability, refeeding, consent and safeguarding safely.
Eating disorders in development disturb more than weight. Restriction can slow linear growth, puberty, bone accrual and cognitive development; purging can cause abrupt electrolyte and cardiac risk at any size; binge eating brings shame and impairment that may be hidden; ARFID can produce micronutrient deficiency or dependence on supplements without body-image psychopathology. Ask about change from the young person's growth path, behaviour and functioning, not whether they resemble a stereotyped patient.
Speak with the young person and carers, including some private time when safe. Use neutral questions about a usual day, skipped meals, rules, feared foods, loss-of-control eating, compensatory behaviour, exercise, weighing, checking, social media, sport, gender or body distress and gastrointestinal or sensory concerns. Ask about substances and unregulated supplements. In diabetes, enquire sensitively about insulin omission and coordinate with the diabetes team because ketosis and glucose instability can become rapidly fatal.
Practice
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PsychiatryOriginal SBA
Risk at higher weight
A 16-year-old has lost 20% of body weight rapidly through restriction, now faints and has an awake pulse of 38, but remains in the usual BMI range. What is the safest response?
Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Physical assessment must be age-aware. Measure weight and height sensitively, plot centiles and calculate percentage median BMI through age eighteen, while examining rate of loss and previous trajectory. Record awake pulse, appropriate lying and standing blood pressure and pulse, temperature, hydration, circulation, muscle function and pubertal development as indicated. Test glucose, electrolytes, bicarbonate, renal, liver, phosphate, magnesium, calcium and blood count according to acuity and obtain an ECG for significant loss, bradycardia, purging, electrolyte or medicine risk.
MEED combines growth or weight, trajectory, cardiovascular status, temperature, hydration, muscle function, ECG, blood findings, intake, purging, exercise, engagement, self-harm and support. It is not an admission calculator. An awake pulse below forty, severe dehydration, serious ECG change, potassium below 2.5 mmol/L, glucose below 3 mmol/L, falling phosphate or other red domains can justify urgent medical care. NICE rejects an absolute BMI admission rule because the safest location depends on active risks and available monitoring.
Treatment is multidisciplinary and developmentally adapted. Medical monitoring and nutritional rehabilitation proceed with psychological work rather than waiting for insight. NICE advises considering anorexia-focused family therapy, commonly across eighteen to twenty sessions over a year, in which carers temporarily help restore nutrition before responsibility returns gradually. The approach is explicitly non-blaming and includes individual time. Individual CBT-ED or adolescent-focused psychotherapy are options when family work is unacceptable, contraindicated or ineffective.
For bulimia, NICE offers bulimia-focused family therapy over approximately eighteen to twenty sessions across six months, with individual CBT-ED as an alternative when needed. For binge-eating disorder, use the age-appropriate NICE psychological pathway and avoid reinforcing dietary restraint or treating weight loss as the primary therapy target. ARFID care often combines dietetic protection of current intake with gradual sensory or fear-based exposure and paediatric, occupational or speech-and-language expertise according to profile.
Refeeding plans distinguish risk without allowing ongoing starvation. Document prior intake, comorbidity, fluid state, ECG and baseline phosphate, potassium and magnesium. Use the specialist service's MEED-aligned standard procedure for calories, vitamins, replacement and blood frequency. Adolescents often tolerate more active starts than historical very-low-calorie regimens when medically uncomplicated and closely monitored, whereas extreme weight, negligible intake, abnormal electrolytes, infection or organ disease requires cautious acute care. Do not improvise one number from an adult generic protocol.
Consent, family and safeguarding need active thought. Involve the young person at every stage and assess competence or capacity for the exact decision. Carers usually enable meal support and monitoring, but privately assess coercion, abuse, unsafe exercise pressure, food insecurity and family capacity. When serious physical risk coexists with refusal, obtain urgent senior legal and mental-health advice; feeding without consent is exceptional and only for a competent trained multidisciplinary team under the correct jurisdictional authority.
Key points
Young people can have anorexia nervosa, atypical anorexia, bulimia, binge-eating disorder, ARFID or another specified disorder at any body size and in any gender.
Plot weight and height over time, assess puberty and use age- and sex-adjusted measures including percentage median BMI through age 18; one current BMI is not a severity assessment.
Ask privately about restriction, fear and rules, bingeing, vomiting, laxatives, diuretics, exercise, water loading, supplements, insulin omission, body checking, sensory avoidance and choking or vomiting fears.
ARFID is driven by sensory sensitivity, feared consequences or low interest rather than weight-shape concern, but its malnutrition and refeeding risks can be equally serious.
MEED is an all-age, multi-domain clinical aid: one red or at least two amber findings should probably be considered high risk, while judgement remains essential.
NICE says not to use a single BMI, weight or illness-duration threshold to decide referral, treatment or admission; suspected eating disorder warrants immediate specialist referral.
Consider anorexia-nervosa-focused family therapy for children and young people, making clear that families are not blamed and giving the young person individual time.
For bulimia in children and young people, offer bulimia-focused family therapy, with CBT-ED when family therapy is unacceptable,
Aetiology
01
Biological and developmental vulnerability
Heritable traits, puberty, temperament and neurodevelopment interact with learning and environment rather than defining one inevitable pathway.
02
Weight-shape reinforcement
Praise, control, anxiety relief and identity can reward restriction or compensation while starvation intensifies preoccupation and rigidity.
03
ARFID-specific drivers
Sensory sensitivity, aversive feeding experience and low appetite or interest can independently or jointly narrow intake.
04
Social and structural pressures
Bullying, sport, social media, discrimination, trauma, food insecurity and family stress can precipitate or maintain disorder behaviour.
Pathophysiology
1
Growth energy deficit
Insufficient energy diverts resources from linear growth, puberty, bone formation, thermoregulation, cardiovascular function and cognitive development.
2
Starvation feedback
Undernutrition increases obsessionality, inflexibility, anxiety and reduced insight, making feared nutritional change progressively harder to tolerate.
3
Purging depletion
Vomiting, laxatives, diuretics and insulin omission disturb fluid, acid-base, glucose and electrolytes, creating arrhythmia and organ risk.
4
Refeeding shift
Renewed carbohydrate metabolism drives phosphate, potassium and magnesium into cells and promotes sodium retention when stores are depleted.
Clinical features and red flags
Restrictive weight-shape syndrome
Restriction, fear of gain or overvaluation and weight-preventing behaviour coexist with loss, growth change or nutritional compromise.
Atypical anorexia presentation
Substantial loss and anorexia psychopathology produce medical and psychological severity while current weight remains outside the low range.
Binge-purge syndrome
Recurrent loss-of-control eating and compensatory vomiting, fasting, medication misuse or exercise may occur without visible weight change.
ARFID profile
Sensory aversion, fear of choking or vomiting, or low interest restricts intake without weight-shape concern as the driver.
Growth and endocrine effect
Crossing centiles, stalled height, delayed puberty, menstrual change, low libido or stress fracture can precede obvious emaciation.
Covert high-risk behaviour
Water loading, hidden weights, purging, insulin omission and compulsive movement distort measures and rapidly alter physiological danger.
Red flags requiring action
MEED treats an awake heart rate below 40 beats/minute as red and warns that tachycardia or an apparently normal pulse in severe undernutrition may indicate infection or hypovolaemia.
For those under 18, percentage median BMI below 70% is a red range, but rapid loss, faltering growth and physiology can be dangerous well above it.
Investigations
01Longitudinal growth assessmentFirst step
Why
Plot height, weight and developmental trajectory and calculate percentage median BMI through age eighteen.
Interpretation and limitations
Rate and centile crossing matter; a population-normal current value cannot cancel substantial loss or faltering growth.
02Age-adjusted physical observations
Why
Assess awake pulse, lying and standing cardiovascular change, temperature, perfusion, hydration and muscle function.
Interpretation and limitations
Use paediatric references and the MEED age-specific framework rather than importing every adult threshold.
03Biochemical and ECG assessment
Why
Detect glucose, electrolyte, renal, liver, phosphate, magnesium and electrical complications of restriction, purging and refeeding.
Interpretation and limitations
A normal result is time-specific and does not prove safety when intake or behaviour remains dangerous.
04Developmental eating-disorder interview
Why
Formulate restriction, bingeing, compensation, ARFID drivers, exercise, body beliefs, onset and functional impact.
Interpretation and limitations
Private and carer accounts are integrated; secrecy and shame call for trust and specificity rather than confrontation.
05
Differential diagnosis
01
Physical gastrointestinal disease
Coeliac, inflammatory, endocrine, neurological and swallowing disorders can reduce intake and may coexist with fear or learned avoidance.
02
Depression or psychosis
Low appetite, self-neglect, food-related beliefs or poisoning fear can restrict eating without primary eating-disorder psychopathology being present.
03
Developmental selective eating
Common preference becomes ARFID when nutritional, growth, supplement-dependence or marked psychosocial consequences meet diagnostic significance and require intervention.
04
Food insecurity or coercion
Inadequate access, neglect and controlling adults can cause restriction and require practical or safeguarding action rather than individual therapy alone.
05
Sport underfueling
Training demand can exceed intake without initial weight-shape psychopathology, but RED-S and an eating disorder may overlap or evolve.
Management
01Suspected disorderRefer and monitor without a weight gateFirst stepEating behaviour, growth, purging, exercise, body concern or ARFID consequences suggest an eating disorder.+
1Complete physical and psychiatric risk assessment, obtain indicated observations, glucose, bloods and ECG, and assess safeguarding and support.
2Refer immediately to an age-appropriate specialist eating-disorder service without waiting for low BMI or a screening threshold.
3Name who will monitor growth, observations, intake, bloods and deterioration while specialist assessment is pending.
02Medical instabilityStabilise in a capable settingA red or concerning multi-domain MEED pattern, rapid decline or acute food or fluid failure is present.+
1Obtain senior paediatric or medical and eating-disorder input, treat glucose, dehydration, electrolytes and organ complications, and choose ward or higher care by active risk.
Complications
01
Cardiovascular and metabolic collapse
Bradycardia, hypotension, hypoglycaemia, electrolyte disturbance and arrhythmia can progress rapidly despite preserved conversation or higher weight.
02
Growth and skeletal harm
Delayed puberty, lost height potential, reduced peak bone mass and stress fractures may have consequences extending into adulthood.
03
Refeeding syndrome
Electrolyte and fluid shifts can cause weakness, delirium, seizure, respiratory failure, arrhythmia and potentially fatal cardiac decompensation.
04
Psychiatric and social loss
Depression, suicide risk, isolation, interrupted education and family strain deepen as food and exercise rules dominate daily life.
05
Coercive-treatment trauma
Late crisis, poor communication and unplanned restraint can damage trust, making early lawful collaborative planning especially important.
Monitoring and follow-up
Measure growth and weight at a clinically justified frequency using consistent technique, interpreting trend with puberty, intake and possible manipulation.
Repeat observations, glucose, electrolytes, phosphate, magnesium and ECG according to MEED risk, purging, refeeding and clinical change.
Track actual meals, supplements, fluid, purging, insulin, activity and distress rather than relying on prescribed plans or verbal reassurance alone.
Ask repeatedly about self-harm, suicide, bullying, abuse, coercion, food security and whether carers can safely implement the plan.
Review therapy response after early agreed intervals and include school participation, relationships, flexibility, growth and family burden.
Plan transitions between paediatric, CAMHS, eating-disorder and adult services well before age boundaries, with named medical ownership.
Special situations
Growth is a vital sign
A stalled height or crossed centile can reveal prolonged energy deficit when a current BMI category appears reassuring.
Families are treatment partners
Focused family therapy mobilises carers around recovery while explicitly rejecting blame and preserving the young person's voice.
ARFID carries medical risk
Absence of weight-shape concern changes formulation, not the urgency of dehydration, deficiency, growth failure or refeeding danger.
Normal bloods can change
Homeostasis may preserve serum values until purging or feeding shifts them, so behaviour and trajectory remain central.
Consent is decision-specific
A young person may understand one investigation but not meaningfully weigh immediate nutritional risk, requiring careful supported assessment.
Common pitfalls
01
Refusing specialist referral because BMI is normal, high or above a locally convenient threshold.
02
Using adult BMI and cardiovascular ranges without paediatric growth and age adjustment.
03
Assuming ARFID is ordinary fussy eating or medically mild because weight-shape concern is absent.
04
Treating carers as the cause of illness or excluding the young person from family-based decisions.
05
Beginning or advancing feeding without a written vitamin, electrolyte, fluid and monitoring plan.
06
Allowing fear of refeeding to sustain starvation-level nutrition in a medically uncomplicated monitored young person.
07
Using parental agreement as an automatic legal solution to active refusal of invasive life-preserving treatment.
contraindicated
or ineffective.
Refeeding is life-preserving treatment delivered through a written specialist protocol with vitamins, phosphate, potassium and magnesium monitoring; excessive caution can itself prolong dangerous undernutrition.
Potassium below 2.5 mmol/L, glucose below 3 mmol/L, falling phosphate, severe dehydration, significant ECG abnormality or marked hypothermia requires urgent medical escalation.
Multiple daily vomiting, laxative or diuretic misuse, water loading, insulin restriction, driven exercise or acute intake failure may create danger that weight does not reveal.
Suicidal intent, severe self-harm, abuse, coercive feeding or weight control, exploitation or a home unable to support essential nutrition requires same-day psychiatric and safeguarding planning.
Mental and home danger can determine care intensity independently of weight or current biochemistry.
06Refeeding risk inventory
Why
Record prior intake, weight severity, recent loss, baseline electrolytes, infection and organ comorbidity.
Interpretation and limitations
The complete risk and service capability select the written feeding and monitoring protocol; BMI alone does not set calories.
2
Start monitored nutrition through an accountable MEED-aligned protocol with vitamins and frequent phosphate, potassium and magnesium review.
3EscalationTransfer only with written medical, dietetic, psychiatric, nursing, legal and escalation responsibilities and do not discharge on one improved observation.
03Specialist therapyMobilise family without blameA child or young person is medically able to undertake structured eating-disorder psychological treatment.+
1For anorexia consider focused family therapy, explaining the temporary carer role, individual time and gradual return of age-appropriate responsibility.
2For bulimia offer focused family therapy and use individual CBT-ED when it is unacceptable, contraindicated or ineffective.
3Review behaviour, growth, physical recovery, function, family burden and the young person's goals, changing model or care intensity when response is inadequate.