Eating restriction and binge eating

Eating restriction is deliberate limitation of the amount or type of food eaten, and binge eating is recurrent episodes of eating an objectively large amount of food with a sense of loss of control.

Both are presentations of eating disorders (anorexia nervosa, bulimia nervosa, binge eating disorder, avoidant restrictive food intake disorder, and other specified disorders). Both may also arise from depression, anxiety, substance use, medical disease and drug effects.

Eating disorders carry the highest mortality of any psychiatric illness group, from medical complications and suicide.

Definitions

• Anorexia nervosa: restriction of energy intake leading to significantly low body weight for age, sex, development and health, intense fear of gaining weight or persistent behaviour preventing weight gain, and disturbed body image or lack of recognition of seriousness
• Subtypes: restricting, and binge eating or purging. Severity by body mass index (BMI) in adults: mild 17 kg/m2 or more, moderate 16 to 16.99, severe 15 to 15.99, extreme under 15. In children and adolescents severity is judged by percentile and clinical state.
• Bulimia nervosa: recurrent binge eating, recurrent inappropriate compensatory behaviours (self induced vomiting, laxatives, diuretics, fasting, excessive exercise, omission of insulin), both on average at least once weekly for 3 months, and self evaluation unduly influenced by shape and weight, not occurring only in anorexia nervosa.
• Binge eating disorder: recurrent binges (large amount within 2 hours with loss of control), eating rapidly, until uncomfortably full, when not hungry, alone because of embarrassment, with guilt or disgust, at least once weekly for 3 months, without regular compensatory behaviour.
• Avoidant restrictive food intake disorder: avoidance or restriction of food due to sensory features, lack of interest, or fear of aversive consequences (choking, vomiting), with weight loss, nutritional deficiency, supplement dependence or impaired function, without body image disturbance.
• Other specified feeding and eating disorders: atypical anorexia nervosa (weight in or over the normal range), purging disorder, night eating syndrome, subthreshold bulimia nervosa and binge eating disorder.

Classification by cause of restriction or binge eating

• Eating disorders: anorexia nervosa, bulimia nervosa, binge eating disorder, avoidant restrictive food intake disorder and other specified disorders.
• Psychiatric: depression, anxiety, obsessive compulsive disorder, posttraumatic stress disorder, autism, ADHD (binge eating), bipolar disorder (appetite change), psychosis (delusional food beliefs), borderline personality disorder, and substance use disorder.
• Medical causes of weight loss and reduced intake: hyperthyroidism, diabetes, malignancy, coeliac disease and inflammatory bowel disease, chronic infection (HIV, tuberculosis), adrenal insufficiency, gastrointestinal obstruction, dysphagia and gastroparesis, chronic kidney and liver disease, and dental disease.
• Medical causes of hyperphagia or binge eating: Kleine-Levin syndrome, Prader-Willi syndrome, hypothalamic lesions, Klüver-Bucy syndrome, frontotemporal dementia, Cushing syndrome, hypothyroidism, hypoglycaemia, premenstrual dysphoric disorder, and sleep related eating disorder.
• Drug related: stimulants, topiramate, metformin and GLP-1 agonists (reduced appetite), antipsychotics, mirtazapine, valproate, steroids, and antihistamines (increased appetite), and cannabis.
• Developmental: paediatric feeding disorders, autism related selective eating, and sensory sensitivity.

Epidemiology. Lifetime prevalence in women is about 1% to 4% for anorexia nervosa, 1% to 3% for bulimia nervosa, and 2% to 5% for binge eating disorder, and about a fifth to a tenth of these in men (binge eating disorder less skewed). Onset is typically in adolescence and early adulthood. Anorexia nervosa has a standardised mortality ratio of about 5 to 6, with suicide accounting for a quarter of deaths.

Younger patients have better recovery with early treatment, and about half recover fully. Mechanisms. Genetic vulnerability, perfectionism, anxiety, dieting, weight stigma, adverse experiences, and neurobiological changes (reward processing, interoception, cognitive rigidity). Starvation maintains symptoms. Binge purge cycles are maintained by restriction, which drives binges, and compensatory behaviour.

Key distinctions. Fear of weight gain with low weight and body image disturbance points to anorexia nervosa. Binges with compensatory purging in a patient of normal or higher weight points to bulimia nervosa. Binges without compensation points to binge eating disorder. Restriction without weight or shape concern points to avoidant restrictive food intake disorder. Weight loss with disinterest in food, anorexia due to illness, and no body image concern suggests medical disease, depression or malignancy.

History

• Eating: usual intake, restriction (calories, food groups, rules, fasting), rituals, meal skipping, binge episodes (frequency, amount, triggers, loss of control), purging (vomiting, laxatives, diuretics, diet pills, enemas), excessive exercise, insulin omission, fluid restriction or loading, and covert eating.
• Weight: current, highest and lowest, rate and amount of change, perceived body image, fear of weight gain, and body checking or avoidance.
• Menstrual history (amenorrhoea, 3 months or more), puberty and growth delay, pregnancy, and contraception.
• Symptoms: fatigue, dizziness, syncope, palpitations, cold intolerance, constipation, abdominal pain and bloating, early satiety, chest pain, muscle weakness and cramps, swelling, poor concentration, and hair loss.
• Mood, anxiety, obsessions, self harm, suicidal thoughts, trauma, substance use, sleep, and perfectionism.
• Medical history: diabetes (especially type 1, with omission of insulin: diabulimia), thyroid disease, coeliac disease, inflammatory bowel disease, gastrointestinal disease, and previous fractures.
• Drugs and substances: laxatives, diuretics, stimulants, thyroid hormone misuse, emetics (ipecac), diet pills, alcohol, cannabis, and vomiting after meals.
• Screening: SCOFF questionnaire (2 or more positive answers suggest an eating disorder).
• SCOFF questions: Do you make yourself sick because you feel uncomfortably full? Do you worry you have lost control over how much you eat? Have you recently lost more than one stone (6.35 kg) in 3 months? Do you believe yourself to be fat when others say you are too thin? Would you say that food dominates your life?
• Family history of eating disorder, depression, and obesity.
• Social: school or work, relationships, family dynamics, bullying, athletic or aesthetic pursuits (dancers, runners, wrestlers, jockeys), social media influence, and vegan or restrictive diets.
• Function: school or work attendance, relationships, driving and safety.

Examination

• Weight, height, BMI (or BMI percentile for age in children and adolescents), and compare with the premorbid growth trajectory. Weigh in a gown after voiding, without hidden weights, and blind to the patient where useful.
• Vital signs: lying and standing blood pressure and pulse (postural drop of 20 mmHg systolic or 10 mmHg diastolic, or rise in pulse over 20 beats/min), temperature, pulse (bradycardia under 50 beats/min by day, under 40 at night), peripheral perfusion, and oxygen saturation.
• General: lanugo hair, hair thinning, dry skin, carotenaemia, acrocyanosis, pressure sores, oedema, Russell sign (calluses on knuckles), parotid enlargement (swollen cheeks), dental enamel erosion, cheilitis, scars from self harm. Proximal muscle weakness (squat test: rise from squat without using arms) and sit up test (rise from lying without using hands).
• Cardiac: bradycardia, murmurs (mitral valve prolapse), arrhythmia, signs of heart failure.
• Abdomen: tenderness, constipation, distension, and masses.
• Mental state: mood, thought content (food and weight), insight, motivation to change, suicidal thoughts, and cognitive function.
• Investigations at bedside: capillary glucose and ketones, ECG, and urine specific gravity.
• Assessment of capacity and consent in severe illness.

Red flags (medical risk markers; any one needs urgent assessment and often admission)

• BMI under 15 kg/m2 (adults) or under 70% of expected weight (children and adolescents); rapid weight loss over 1 kg weekly.
• Pulse under 40 beats/min, systolic blood pressure under 90 mmHg (adolescents under 80), postural fall over 20 mmHg, temperature under 35.5 degrees Celsius.
• ECG: QTc over 450 ms in men or 460 ms in women (children over 460 ms), bradycardia under 40 beats/min, arrhythmia, or conduction block.
• Electrolytes: potassium under 3.0 mmol/L, sodium under 130 mmol/L, phosphate under 0.5 mmol/L, magnesium under 0.5 mmol/L, hypoglycaemia (under 3.0 mmol/L), raised urea or creatinine, and raised liver enzymes.
• Syncope, chest pain, severe weakness, inability to rise from a squat, seizures, or confusion.
• Refusal of all food or fluids for several days.
• Suicidal ideation, self harm, or psychosis.
• Pregnancy with low weight.
• Diabetes with insulin omission, ketoacidosis, or recurrent hypoglycaemia.
• Purging more than several times daily, severe laxative or diuretic misuse, or vomiting of blood.
• Rapid deterioration in a child or adolescent.
• Abdominal pain with distension (gastric dilatation, superior mesenteric artery syndrome).
• Refeeding risk: very low intake for over 5 days, BMI under 16 kg/m2, weight loss over 15% in 3 to 6 months, low baseline potassium, phosphate or magnesium, alcohol misuse, or insulin and diuretic use.

Special groups

• Children and adolescents: use growth charts and percentiles. Stunting, delayed puberty, and primary amenorrhoea indicate severity. Rapid decline can occur without a very low BMI. Family should be involved.
• Men and boys: under recognised. Ask about muscularity concerns, excessive exercise, and supplements.
• Athletes: relative energy deficiency in sport (low energy availability, menstrual disturbance, stress fractures).
• Pregnancy: risk of miscarriage, low birth weight, hyperemesis. Close obstetric and eating disorder care.
• Type 1 diabetes: insulin omission causes hyperglycaemia, ketoacidosis, and complications.
• Older adults: new eating restriction suggests depression, malignancy, dementia or dysphagia.
• Autism and ADHD: sensory selectivity and avoidance (avoidant restrictive food intake disorder), and binge eating.
• Region specific: food insecurity and malnutrition, HIV and tuberculosis related wasting, and cultural beliefs about body size.

Eating disorders

• Anorexia nervosa (restricting; binge eating or purging).
• Atypical anorexia nervosa.
• Bulimia nervosa.
• Binge eating disorder.
• Avoidant restrictive food intake disorder.
• Purging disorder, night eating syndrome, and other specified feeding and eating disorders.
• Rumination disorder and pica.

Other psychiatric disorders

• Major depressive disorder (appetite loss or increase, with no weight or shape concern).
• Anxiety disorders and specific phobia of vomiting or choking.
• Obsessive compulsive disorder (food related rituals and contamination).
• Posttraumatic stress disorder.
• Psychotic disorders with delusions about food or poisoning.
• Bipolar disorder (increased appetite in depression, reduced in mania).
• Borderline personality disorder and substance use disorder (stimulants, cannabis).
• Somatic symptom disorders and functional gastrointestinal disorders.
• Autism spectrum disorder (selective eating).
• ADHD with impulsive eating.

Medical causes of weight loss

• Hyperthyroidism and diabetes mellitus.
• Malignancy (lymphoma, gastric, pancreatic, hypothalamic and brain tumours).
• Coeliac disease, inflammatory bowel disease, and peptic ulcer disease.
• Chronic infection: HIV, tuberculosis, chronic parasitic infection.
• Adrenal insufficiency (Addison disease).
• Chronic kidney, liver, heart or lung disease.
• Dysphagia, achalasia, gastroparesis, superior mesenteric artery syndrome, and dental disease.
• Hypercalcaemia and panhypopituitarism.
• Cystic fibrosis and malabsorption.

Medical and neurological causes of binge eating or hyperphagia

• Kleine-Levin syndrome and sleep related eating disorder.
• Prader-Willi syndrome and hypothalamic lesions.
• Frontotemporal dementia.
• Cushing syndrome, hypothyroidism, and insulinoma.
• Premenstrual dysphoric disorder.
• Drug induced (antipsychotics, mirtazapine, valproate, corticosteroids, and cannabis).

Step 1. Assess medical risk and stabilise. Measure vital signs, glucose, ECG and basic bloods in every patient with restriction or purging. Identify refeeding risk and need for admission. Assess suicide risk. Step 2. Confirm the diagnosis. Take a detailed eating, weight and behaviour history with collateral information from family. Use the SCOFF, Eating Disorder Examination Questionnaire, or Eating Disorder Examination interview (specialist).

Apply diagnostic criteria. Assess body image, motivation and comorbidity (depression, anxiety, obsessive compulsive disorder, trauma, substance use, autism).

Step 3. First line tests

• Full blood count (anaemia, leucopenia), urea, creatinine, electrolytes (sodium, potassium, chloride, bicarbonate), calcium, magnesium, phosphate, glucose, liver tests, albumin, creatine kinase, thyroid stimulating hormone, and C-reactive protein.
• Urine analysis (specific gravity, ketones).
• 12 lead ECG (QTc, bradycardia, arrhythmia, U waves).
• Pregnancy test in women of reproductive age.
• Zinc and vitamin B12, folate, vitamin D, and iron studies when malnutrition is suspected.

Step 4. Targeted tests

• Coeliac serology and faecal calprotectin for gastrointestinal symptoms.
• Luteinising hormone, follicle stimulating hormone, oestradiol, prolactin and testosterone for amenorrhoea. Bone density scan (DXA) after 6 to 12 months of amenorrhoea or low weight.
• Echocardiography for bradycardia with symptoms, murmurs or heart failure signs.
• Abdominal imaging, endoscopy, or barium studies for pain, vomiting or dysphagia.
• Cortisol, HIV testing, chest radiograph and tuberculosis tests where wasting persists.
• MRI brain when atypical features, headache or visual symptoms.
• Dental review.
• Squat and sit up tests for muscle function.

Step 5. Interpretation. Normal laboratory values do not exclude serious risk. Potassium, phosphate and magnesium can be normal until refeeding. Vomiting causes hypokalaemic hypochloraemic metabolic alkalosis, and laxative misuse causes hypokalaemic metabolic acidosis. Raised amylase indicates vomiting. Low T3, low sex hormones and mildly raised cholesterol and liver enzymes are consequences of starvation. Adolescents can have severe complications at higher BMI. Assess weight against growth trajectory, not BMI alone.

Limits. Patients commonly deny symptoms, minimise intake or manipulate weight. Collateral information is essential. BMI alone does not reflect risk, and weight can be normal or high with serious purging.

Immediate

• Treat life threatening abnormalities: arrhythmia, hypoglycaemia, severe electrolyte disturbance, dehydration, and sepsis.
• Hypoglycaemia: 10% dextrose 150 to 200 mL intravenously (children 2 mL/kg), then oral carbohydrate. Give thiamine before glucose in patients at risk of Wernicke encephalopathy.
• Hypokalaemia: oral potassium chloride (modified release 12 mmol two to three times daily, titrated to level) when potassium is 2.5 to 3.4 mmol/L and the patient is asymptomatic.
• If under 2.5 mmol/L, symptomatic or with ECG changes, give intravenous potassium chloride 10 to 20 mmol/hour via a central line, or 10 mmol/hour peripherally in dilutions of 40 mmol/L, with continuous cardiac monitoring. Correct magnesium first or at the same time: magnesium sulphate 8 to 20 mmol intravenously over 12 to 24 hours.
• Hypophosphataemia: oral phosphate supplement 500 mg (phosphate 16 mmol) two to three times daily, or intravenous sodium glycerophosphate 10 mmol over 8 to 12 hours when phosphate is under 0.5 mmol/L.
• Hyponatraemia: correct slowly (not over 8 mmol/L in 24 hours), as rapid correction risks osmotic demyelination.
• Fluids: oral rehydration preferred; intravenous isotonic fluids cautiously (avoid fluid overload and refeeding oedema).
• Arrhythmia with prolonged QTc: stop QT prolonging drugs, correct potassium and magnesium, and monitor.
• Vitamin supplementation before and during refeeding: thiamine 100 mg orally three times daily (or 200 to 300 mg daily), or 200 to 500 mg intravenously three times daily for 3 days when at high risk, with a multivitamin and mineral supplement.

Nutritional rehabilitation and refeeding

• Refeeding syndrome risk: start low and increase gradually, with daily monitoring of potassium, phosphate, magnesium and glucose in the first 3 to 7 days (every 12 hours in high risk patients) and daily ECG in severe cases.
• Adult high risk: start 5 to 10 kcal/kg daily (about 10 kcal/kg in the highest risk) increasing over 4 to 7 days to 20 to 30 kcal/kg daily and further to 35 to 40 kcal/kg to achieve weight gain. Moderate risk: 15 to 20 kcal/kg daily rising rapidly.
• Weight gain target: 0.5 to 1 kg weekly for outpatients, 0.5 to 1.5 kg weekly in inpatients. In children and adolescents, start with about 1400 to 1800 kcal daily (about 40 to 60 kcal/kg) and increase over days to weeks, with close monitoring.
• Oral feeding preferred, with supplements. Nasogastric feeding when oral intake fails or the patient is at medical risk, or in emergencies under supervision; nasogastric feeding can be used with capacity limits or legal powers in severe cases. Parenteral nutrition is rare.
• Supervised meals, a meal plan prepared with a dietitian, three meals and two to three snacks daily, and reduction in exercise.
• Correct vitamin and mineral deficits: zinc 15 to 30 mg daily for 2 to 3 months, vitamin D 800 to 2000 units daily, calcium 1000 to 1200 mg daily from food or supplement, and iron by deficiency.
• Bone health: weight restoration and resumption of menses are the best treatment. Oestrogen and bisphosphonates have limited effects. Avoid oral contraception as treatment for bone loss. In adolescents with persistent amenorrhoea and fractures, transdermal oestrogen is a specialist option.

Psychological treatment

• Anorexia nervosa, children and adolescents: family based treatment (about 20 sessions over 6 to 12 months), in which parents take charge of refeeding in the first phase. Alternatives: adolescent focused therapy and multifamily therapy.
• Anorexia nervosa, adults: specialist supportive clinical management, cognitive behavioural therapy for eating disorders (enhanced version, 30 to 40 sessions), Maudsley anorexia nervosa treatment for adults, or focal psychodynamic therapy.
• Bulimia nervosa: supported self help (8 to 12 weeks) then cognitive behavioural therapy for bulimia nervosa (16 to 20 sessions over 20 weeks), and family therapy for adolescents.
• Binge eating disorder: supported self help for 12 to 16 weeks, group or individual cognitive behavioural therapy, or interpersonal therapy.
• Avoidant restrictive food intake disorder: cognitive behavioural therapy adapted for the disorder, gradual exposure to foods, family involvement and dietetic support.
• Treat co-occurring conditions at the same time.

Pharmacological treatment

• There is no drug that treats anorexia nervosa. Drugs are used only for comorbidity (depression, anxiety, obsessive compulsive disorder) once weight has recovered, since SSRIs are ineffective in underweight states.
• Olanzapine 2.5 mg at night increased to 5 to 10 mg may help in severe anorexia nervosa (specialist use), with monitoring of ECG, glucose and weight.
• Bulimia nervosa: fluoxetine 60 mg orally once daily (start at 20 mg, increase to 60 mg over 1 to 2 weeks) alongside psychological therapy. Maximum 80 mg under specialist care. Avoid bupropion (seizure risk).
• Binge eating disorder: lisdexamfetamine 30 mg once daily increased by 20 mg weekly to 50 to 70 mg (maximum 70 mg) for moderate to severe disease in adults (specialist use; contraindicated in cardiac disease, hypertension, and substance misuse).
• Alternatives: SSRI such as sertraline 50 to 200 mg, topiramate 25 mg at night increased to 100 to 200 mg (not in women who can become pregnant without effective contraception, because of teratogenicity and effect on contraceptives).
• Avoid treating bulimia nervosa with antidepressants alone.
• Comorbid depression after weight recovery: sertraline 50 mg increased to 100 to 200 mg, or fluoxetine 20 to 40 mg.

Complication management

• Type 1 diabetes with insulin omission: restore insulin with supervised administration, diabetes team and eating disorder team together. Avoid abrupt reduction of high glucose to reduce retinopathy worsening.
• Constipation: increase fibre and fluid, and macrogol 1 sachet daily. Avoid stimulant laxatives.
• Gastric symptoms: small frequent meals; domperidone 10 mg three times daily before meals for up to 2 weeks for gastroparesis (check QTc).
• Dental: fluoride, avoid brushing straight after vomiting, rinse with water, and dental review.
• Osteoporosis: weight restoration and return of menses are the main treatment, with calcium and vitamin D.
• Amenorrhoea: counsel about fertility, as ovulation can occur despite no menses.

Special populations

• Pregnancy: obstetric and eating disorder care, close monitoring of weight gain, foetal growth scans, vitamins and folic acid 5 mg daily in the preconception period and first 12 weeks for low weight women.
• Adolescents: parental involvement, school support, and monitoring of growth, puberty and bone health.
• Kidney and liver impairment: adjust drug doses and electrolyte replacement.
• Older adults: evaluate for depression, malignancy and dysphagia. Cautious refeeding.
• Men: screen for hypogonadism and muscle dysmorphia.

Monitoring. Weight weekly (outpatients) or twice weekly in higher risk, BMI or percentile, vital signs including postural measurements, electrolytes (daily for refeeding, then weekly until stable), ECG, glucose, behaviours (bingeing, purging, exercise), mood and suicidal thoughts, menstrual function, and bone density yearly if low.

Referral and escalation. Refer all suspected eating disorders to a specialist eating disorder service, early (first 3 years of illness gives the best outcome). Urgent referral (within 1 week) for medical risk features or rapid weight loss. Paediatric and adolescent services for under 18 years. Endocrinology, gastroenterology, cardiology, dietetics and dental services as needed. Obstetric care in pregnancy. Admission criteria

• Medical: BMI under 15 kg/m2 (children and adolescents under 70% of median BMI), pulse under 40 beats/min, systolic pressure under 90 mmHg. Also postural hypotension, hypothermia, prolonged QTc or arrhythmia, potassium under 3.0 mmol/L, phosphate or magnesium low, hypoglycaemia, syncope, seizures, or acute food or fluid refusal.
• Psychiatric: suicidal intent, psychosis, severe self harm, or failure of outpatient care with continued weight loss.
• Social: unsafe home, no supervision, or safeguarding concern.
• Compulsory treatment may be needed when capacity is impaired and risk is high.

Discharge and follow up. Written meal plan, defined weight and behaviour goals, named clinician, relapse plan, and follow up within 1 week of discharge, then weekly for the first month. Safety net advice: return for fainting, chest pain, palpitations, severe weakness, confusion, vomiting blood, suicidal thoughts, inability to eat or drink, or rapid weight loss.