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 and medical instability
Paediatrics and child health · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
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Medical or psychiatric instability
Syncope, marked bradycardia, hypotension, hypothermia, dehydration, electrolyte disturbance, ECG abnormality, acute food or fluid refusal, uncontrolled compensatory behaviour or immediate suicide risk can make an eating disorder life threatening at any weight.
Action: Use ABCDE, obtain lying and standing observations, glucose, ECG and urgent bloods, correct immediately dangerous abnormalities with paediatric and specialist input, institute supervised safety and nutrition planning, and arrange same-day hospital assessment rather than relying on body mass index alone.
Overview
Recognise eating disorders across body sizes and presentations, detect cardiovascular, metabolic, behavioural and psychiatric instability early, arrange safe same-day paediatric and mental-health care, begin cautious nutrition support, and coordinate evidence-based family, psychological and physical recovery.
Eating disorders are defined by behaviour, cognition, nutrition and impairment, not by looking underweight. Establish maximum and minimum weight, speed and amount of change, growth-centile movement, menstrual or pubertal change and the young person's own goals and fears. Ask neutrally about skipped meals, rules, calorie or label checking, fear foods, binge loss of control, vomiting, exercise, laxatives, diuretics, supplements, water loading and manipulation of prescribed treatments such as insulin. Collateral information can identify concealed deterioration, while the young person still deserves private time for abuse, identity, mood and safety disclosure.
Examination seeks instability rather than proof of motivation. Measure pulse, temperature, respiratory rate and blood pressure, including postural change when safe. Assess hydration, capillary refill, peripheral temperature, muscle weakness, oral and dental injury, parotid enlargement, abdominal symptoms, bruising and self-harm. Plot height and weight on age-appropriate charts and review previous data. A person at a higher weight can have severe malnutrition after rapid loss, and fluid loading or oedema can conceal trajectory. Avoid repeatedly displaying or discussing weight when this increases distress; agree how measurements will be communicated.
Practice
Two practice questions
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Paediatrics and child healthOriginal SBA
Risk beyond body mass index
A 16-year-old at an average-range BMI has lost substantial weight rapidly, is dizzy on standing and eats almost nothing. Initial electrolytes are normal. What is the best interpretation?
Sources and review status3 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
NICE Eating disorders NG69Recognition, referral, assessment and psychological and physical treatment recommendations for eating disorders across ages.
Royal College of Psychiatrists MEED guidanceMedical-emergency risk assessment and management principles integrating trajectory, physical findings, behaviours and psychiatric danger.
NICE Nutrition support CG32National principles for nutrition support and identifying, preventing and monitoring refeeding problems.
Obtain ECG, glucose and laboratory assessment according to severity and behaviour. Typical tests include full blood count, urea and electrolytes, phosphate, magnesium, calcium, liver profile and bone or endocrine assessment when indicated. Normal initial tests do not make ongoing severe restriction safe; vital signs, trajectory and behaviour remain important. Conversely, isolated mild abnormalities need clinical interpretation rather than punitive treatment. Use MEED principles and local specialist criteria to integrate physical observations, bloods, ECG, rate of loss, intake, compensatory behaviours and psychiatric risk.
Treatment aligns medical stabilisation with nutritional and psychological recovery. Agree supervision of meals, fluids, toilets, activity and leave proportionately in hospital. Refeeding plans should deliver meaningful nutrition with scheduled biochemical and clinical monitoring, electrolyte replacement and thiamine when indicated under protocol. Bed rest is not a default long-term therapy; activity is restricted only for medical safety and then restored deliberately. For anorexia nervosa in children and adolescents, specialist family therapy focused on eating is commonly recommended, while individual or family psychological treatments are selected by diagnosis and need.
Refusal requires careful assessment of competence or capacity, effect of malnutrition on weighing information, parental responsibility, mental-health legislation and best interests. Seek senior paediatric, child-psychiatry and legal advice early rather than bargaining while physiology worsens. Communicate that compulsory measures, when legally authorised, aim to preserve life and should use the least restrictive approach. Discharge only with a shared plan covering nutrition, activity, physical observations, crisis contacts, education, family support and named ownership across paediatrics, primary care and the eating-disorder team.
Key points
Ask about recent weight trajectory, restriction, binge episodes, vomiting, exercise, laxatives, diuretics, insulin manipulation, body concerns, sensory avoidance and feared consequences of eating.
Do not screen by appearance or BMI alone: atypical anorexia, bulimia, binge-eating disorder and avoidant restrictive food intake disorder can cause major medical and psychosocial harm across body sizes.
Record pulse, blood pressure lying and standing, temperature, hydration, weight and height on appropriate growth charts; interpret trends, pubertal stage and previous trajectory.
Medical warning features include syncope, chest pain, weakness, acute refusal, poor perfusion, bradycardia, postural change, hypothermia, hypoglycaemia, electrolyte abnormality and ECG disturbance.
Use same-day paediatric or acute medical assessment when instability is possible and involve a specialist eating-disorder service early rather than waiting for diagnostic certainty.
Nutrition is essential treatment; establish a specialist meal and fluid plan with electrolyte monitoring based on risk, and do not underfeed solely from fear of refeeding syndrome.
Family-based treatment is central for many children and adolescents with anorexia nervosa; avoid blaming relatives and give carers practical responsibility and support matched to development.
Aetiology
01
Biological vulnerability
Genetic liability, temperament, neurodevelopment, puberty and altered reward or threat processing interact; no single personality, family pattern or body type explains illness.
02
Psychological and social factors
Perfectionism, anxiety, trauma, bullying, weight stigma, identity distress and social comparison can contribute, while restriction and compensatory behaviours become self-reinforcing coping strategies.
03
Illness and access factors
Diabetes, gastrointestinal symptoms, food allergy, sport, poverty, cultural food practice and avoidant sensory experiences may shape presentation and complicate recognition or treatment access.
Pathophysiology
1
Energy-deficit adaptation
Reduced energy availability suppresses reproductive and thyroid axes, slows heart rate and gut motility, impairs growth and bone accrual and redistributes limited physiological resources.
2
Purging electrolyte loss
Vomiting, laxatives, diuretics or insulin manipulation disturb potassium, chloride, acid-base status and volume, increasing renal injury and malignant arrhythmia risk.
3
Refeeding shifts
Renewed carbohydrate delivery increases insulin and cellular phosphate, potassium and magnesium uptake; depleted patients can develop oedema, cardiac failure, neurological dysfunction and arrhythmia.
4
Cognitive entrenchment
Starvation increases rigidity, preoccupation, anxiety and impaired concentration, making collaborative decisions harder and reinforcing avoidance despite serious physical consequences.
Clinical features and red flags
Restrictive pattern
Intake rules, fear foods, weight loss, growth faltering, body checking, cold intolerance, amenorrhoea or reduced energy suggest restrictive eating pathology.
Binge and purge pattern
Loss-of-control eating, secrecy, vomiting, laxative use, dental erosion, parotid swelling or electrolyte changes may occur at any weight.
Avoidant restrictive intake
Sensory aversion, low interest or fear of choking or vomiting limits nutrition without necessarily involving weight-and-shape concern.
Physical instability
Syncope, postural symptoms, bradycardia, hypotension, hypothermia, poor perfusion, weakness, hypoglycaemia or ECG change signals acute medical danger.
Psychiatric instability
Suicidal intent, severe self-harm, psychosis, uncontrolled exercise, absconding or inability to cooperate with essential nutrition can make outpatient care unsafe.
Red flags requiring action
Rapid recent weight loss, minimal intake or acute food and fluid refusal can cause serious instability even when weight remains within or above a population reference range.
Syncope, chest pain, profound weakness, confusion, seizures, bradycardia, postural hypotension, hypothermia or poor peripheral perfusion requires urgent medical assessment.
Hypoglycaemia, hypokalaemia, hypophosphataemia, hypomagnesaemia, acute kidney injury, transaminitis or prolonged QTc raises concern for metabolic decompensation and arrhythmia.
Investigations
01Serial growth and weight dataFirst step
Why
Quantify trajectory relative to the young person's developmental baseline.
Interpretation and limitations
Rate and magnitude of loss, centile crossing, growth slowing and pubertal suppression inform severity; a single BMI cannot exclude significant malnutrition.
02Lying and standing observations
Why
Detect circulatory adaptation, dehydration and haemodynamic compromise.
Interpretation and limitations
Integrate heart rate, blood pressure change, symptoms, temperature and perfusion with age, athletic baseline and trajectory; concerning findings require same-day senior review.
03ECG
Why
Identify bradyarrhythmia, QTc abnormality and effects of electrolyte or medicine disturbance.
Interpretation and limitations
Review rate, rhythm, intervals and repolarisation alongside potassium, magnesium, calcium, medication and symptoms; abnormality or syncope lowers the threshold for monitored care.
04Glucose electrolytes and organ profile
Why
Find acute metabolic effects and establish a refeeding baseline.
Interpretation and limitations
Check glucose, sodium, potassium, bicarbonate, renal function, phosphate, magnesium, calcium and liver tests according to risk; trends after feeding are as important as baseline values.
05
Differential diagnosis
01
Endocrine or metabolic disease
Diabetes, thyroid disease, adrenal insufficiency and other metabolic disorders can cause weight change, vomiting or altered menstruation and may coexist with disordered eating.
02
Gastrointestinal or inflammatory illness
Coeliac disease, inflammatory bowel disease, malabsorption, chronic infection and malignancy can produce weight loss and food avoidance requiring phenotype-led investigation.
03
Depression or neurodevelopmental feeding difficulty
Low mood, autism, sensory aversion, emetophobia and avoidant restrictive food intake disorder may reduce intake without weight-and-shape overvaluation.
04
Safeguarding and deprivation
Neglect, food insecurity, coercion, fabricated illness and abuse can alter access to food or reported symptoms and require a protective formulation.
Management
01EmergencyStabilise body and safetyFirst stepPhysical observations, bloods, ECG, intake or psychiatric assessment suggests acute instability.+
1Use ABCDE, check glucose, obtain ECG and urgent laboratory tests and involve senior paediatrics or acute medicine immediately.
2Supervise the young person, stop unsafe exercise or purging opportunities proportionately and complete direct suicide and safeguarding assessment.
3Correct immediately dangerous abnormalities under specialist protocol while establishing a monitored nutrition and fluid plan.
4Seek eating-disorder psychiatry, dietetic and legal input early when essential care is refused or coercion may be necessary.
02Specialist careBuild an integrated formulationAn eating disorder is suspected whether or not emergency admission is needed.+
1Refer promptly to the age-appropriate specialist eating-disorder service without waiting for an arbitrary weight threshold.
Complications
01
Cardiac and metabolic collapse
Bradyarrhythmia, ventricular arrhythmia, hypoglycaemia, dehydration, renal injury and refeeding syndrome can cause sudden deterioration and death.
02
Growth reproductive and bone harm
Delayed growth, pubertal suppression, amenorrhoea, low bone mineral accrual and stress fractures may persist beyond apparent weight restoration.
03
Gastrointestinal and dental injury
Gastroparesis, constipation, reflux, salivary enlargement, enamel erosion and oesophageal injury can perpetuate pain, shame and avoidance.
04
Psychiatric and social impairment
Depression, anxiety, obsessive symptoms, self-harm, suicide risk, educational loss, isolation and family distress contribute substantially to morbidity.
Monitoring and follow-up
During acute care, monitor heart rate, blood pressure, temperature, perfusion, symptoms, fluid balance and supervised intake at a frequency matched to instability.
Repeat glucose, phosphate, magnesium, potassium, renal and liver tests according to baseline risk and the pace and stage of refeeding.
Track height, weight trajectory, pubertal progression and functional recovery using a consistent, trauma-informed measurement and communication plan.
Review bingeing, vomiting, exercise, laxatives, water loading, insulin manipulation, self-harm, suicide risk and safeguarding at each clinically significant transition.
Measure school participation, cognition, sleep, relationships, family burden and return to safe activity rather than treating scale change as the sole outcome.
Ensure missed appointments or unexpected weight and observation changes trigger active contact and review rather than administrative discharge.
Special situations
Instability crosses weight categories
Rapid loss, purging and starvation physiology can produce severe medical risk while population BMI remains average or high.
Normal bloods are temporary information
Homeostasis can preserve initial results despite dangerous restriction, so behaviour, trajectory, vital signs and ECG remain central.
Parents are not the cause
Carers often become an essential treatment resource and need practical coaching, respite and unified messages from the team.
Nutrition improves cognition
Starvation-related rigidity and anxiety can limit weighing and engagement; compassionate persistence with nutrition supports later psychological work.
Diabetes changes the hazard
Insulin restriction can cause rapid ketoacidosis without the expected visible weight pattern and needs joint diabetes and eating-disorder ownership.
Common pitfalls
01
Excluding an eating disorder because the young person does not appear underweight.
02
Waiting for abnormal blood tests before responding to rapid loss, acute refusal or concerning observations.
03
Prescribing prolonged very low-calorie refeeding solely from fear of refeeding syndrome without specialist monitoring and progression.
04
Discussing weight, calories or exercise in a shaming or competitive way that reinforces illness and impairs disclosure.
05
Separating suicide risk from medical risk or asking only about one while the other drives immediate danger.
06
Discharging after short-term physiological improvement without a specialist nutrition, family, monitoring and crisis plan.
Assess suicide, self-harm, abuse, bullying, substance use, exercise compulsion and treatment resistance directly, with supervised safety and legal advice when life-saving care is refused.
Manage comorbid anxiety, depression, diabetes and neurodevelopmental needs without allowing them to fragment physical monitoring, nutrition restoration or safeguarding.
Frequent vomiting, laxative or diuretic misuse, excessive exercise, water loading, insulin omission or concealed substances can make apparently stable measurements misleading.
Suicidal intent, severe self-harm, psychosis, inability to maintain safety, abuse or coercive control requires an urgent parallel mental-health and safeguarding response.
Comorbidity-directed assessment
Why
Identify competing or coexisting causes of weight loss and impairment.
Interpretation and limitations
Use history and examination to select coeliac, inflammatory, endocrine, pregnancy, infection or other tests, avoiding broad repeated panels that delay specialist eating-disorder care.
2Share growth trajectory, vital signs, tests, behaviours, comorbidity, suicide risk, safeguarding and family context rather than a diagnosis label alone.
3Agree diagnosis-specific psychological treatment, nutritional restoration, family role and physical monitoring with accessible adjustments.
4Name who monitors bloods, ECG, growth, medicines, crisis risk and missed appointments across services.
03RecoveryRestore nutrition and participationImmediate instability is controlled and sustained treatment can proceed.+
1Progress meals and snacks under the specialist plan while monitoring refeeding risk, gastrointestinal symptoms and compensatory behaviour.
2Review school, sleep, activity, social connection, puberty, bone health and family burden as part of recovery outcomes.
3Treat comorbid mental or physical illness without using medication as a substitute for core eating-disorder therapy.
4Plan relapse indicators, rapid re-entry, transition and crisis contacts before reducing the intensity of support.
Key medicines and prescribing safety1 treatment · regimens, roles and cautions+
Supports carbohydrate metabolism and reduces neurological risk during refeeding in depleted patients.
Thiamine
Give oral or parenteral thiamine at the age-appropriate dose and duration specified by the local paediatric refeeding protocol before and during early nutrition when deficiency or high refeeding risk is identified.
Do not let vitamin administration delay nutrition or correction of hypoglycaemia; use the protocol route for vomiting or severe deficiency and monitor for rare parenteral hypersensitivity.