Eating disorders, obesity and weight change

Explore the pattern without stigma

Document reliable weight trajectory, intake, appetite, activity, medicines and systemic symptoms. Distinguish intentional change from unexplained loss, and ask about body image, restriction, bingeing, vomiting, laxatives and excessive exercise. Eating disorders occur at any body size and may be concealed by a normal or high BMI. Weight-focused praise can reinforce a dangerous restrictive pattern. Ask privately about distress, self-harm and functional impact, using neutral language and explaining why medical assessment is needed.

Unintentional loss raises malignancy, infection, endocrine, GI, psychiatric and social causes. Consider thirst/polyuria, dysphagia, diarrhoea, bleeding, fever, night sweats, dental problems and food insecurity. Examine and investigate according to the findings rather than ordering a universal “cancer panel.” Hyperthyroidism, uncontrolled diabetes, malabsorption and depression have different management. A known psychiatric diagnosis must not prevent investigation of new systemic signs. Assess nutrition and safety while the cause is clarified.

Eating-disorder diagnoses and danger

Anorexia nervosa includes restrictive intake, low weight in context and fear/behaviour preventing weight gain with disturbed body-image/weight appraisal. Atypical anorexia can have similar psychological features and serious medical harm without low BMI. Bulimia involves bingeing with compensatory behaviours, while binge-eating disorder lacks regular compensatory behaviour. ARFID involves restricted intake with nutritional or psychosocial consequences without the characteristic weight/shape drive. A diagnostic label does not determine medical stability by itself.

Check pulse, pressure including postural change where safe, temperature, hydration, ECG and glucose/electrolytes including phosphate, magnesium and potassium as indicated. Bradycardia, hypotension, syncope, arrhythmia, electrolyte disturbance, rapid loss or dehydration can require admission. A young person can look well while medically unstable. Purging can produce hypokalaemia and alkalosis, with QT/arrhythmia risk. Assess suicide risk and psychiatric comorbidity concurrently. Use the local age-specific eating-disorder pathway and senior multidisciplinary input rather than one BMI threshold.

Refeeding and treatment

Refeeding can cause shifts in phosphate, potassium and magnesium with fluid and cardiac complications. Risk relates to nutritional depletion and intake history, not only body size. Obtain initial investigations and coordinate the nutrition/hydration plan with the admitting team, including thiamine and monitoring when indicated. Do not begin an unplanned large caloric/fluid load in a depleted patient. Equally, fear of refeeding should not result in indefinite withholding of nutrition; a structured supervised plan is essential. Urgent hypoglycaemia still requires immediate treatment.

Treatment combines medical monitoring, nutritional rehabilitation and appropriate psychological care. Family-based approaches can be valuable for adolescents, with individual assessment of safety and relationships. Adults may receive disorder-specific psychological therapy through suitable services. Explain that medicines alone do not correct the central restrictive pattern of anorexia. Arrange a named team and timely review, and address access barriers. Avoid dismissive language about “just eating” or treating refusal as proof of manipulation. Capacity is assessed for the specific decision, with lawful urgent care when necessary.

Obesity and voluntary weight loss

Assess adiposity-related health, waist/function, blood pressure, glucose, sleep apnoea, liver disease, mobility and medicines rather than judging risk from appearance alone. BMI is a useful population measure but has limitations for individuals. Ask permission to discuss weight and agree goals that matter to the person. Nutrition, physical activity, sleep and behavioural support should be feasible and culturally appropriate. Food access, disability, shift work and medication effects can limit standard advice. Avoid assuming a person has failed because previous plans were inaccessible.

Weight-management medicines and bariatric surgery are options for selected patients after assessment of benefits, risks, contraindications and follow-up. Current product indications and PBS access differ; do not assume clinical suitability guarantees subsidy. Discuss adverse effects, pregnancy planning and the possibility of weight regain after stopping a medicine. Screen for eating disorders before recommending restrictive strategies. Bariatric procedures require long-term nutritional and complication monitoring; vomiting, abdominal pain or neurological symptoms afterwards may need urgent assessment rather than being attributed to routine dieting.

Applied clinical decisions

A normal-BMI adolescent who has rapidly lost weight, faints and restricts intake needs medical and psychiatric assessment, not congratulations. A patient with involuntary loss, thirst and polyuria needs prompt diabetes/metabolic assessment. Another patient seeking intentional weight reduction can discuss evidence-based options with realistic functional goals and monitoring. These cases test whether the clinician uses trajectory and physiology rather than a body-size stereotype.

Provide a clear review plan, including symptom, vital-sign and laboratory monitoring when needed. Explain escalation signs such as syncope, chest pain, inability to maintain intake, severe vomiting or suicidal distress. Coordinate dietetics, mental health and medical care so the person receives compatible advice. Carers need guidance and support but do not replace the patient's voice or confidentiality rights.

RCH eating-disorder emergency guidance and Australian eating-disorder resources.

Motivational interviewing and brief intervention

Motivational interviewing explores ambivalence while respecting the patient's autonomy. Ask permission to discuss smoking, alcohol, nutrition or activity, then use open questions, affirmations, reflective listening and summaries. Rather than arguing that the patient should change, elicit their own reasons: “What concerns you about your drinking?” Reflect both sides of ambivalence and invite a realistic next step. Readiness and confidence are different; a patient who wants change may need practical help to make it possible.

A brief intervention links an identified risk to personalised feedback, advice given with permission, an agreed action and follow-up. For example, after screening reveals hazardous alcohol use, explain the connection with sleep and blood pressure, ask which change feels feasible and agree a measurable reduction plan. Assess dependence first: abruptly stopping alcohol can cause dangerous withdrawal, so a reduction conversation may need supervised withdrawal planning. For weight management, ask about food security, medications, sleep and mobility rather than prescribing a standard diet without context. A patient choosing a short daily walk may be more ready to succeed than one accepting an imposed target. Review progress without blame and adapt the plan. RACGP motivational interviewing techniques explain this counselling approach.

Review checkpoints

• Eating-disorder medical instability can occur at any BMI.
• Refeeding risk requires assessment and appropriate monitoring.
• Motivational interviewing explores ambivalence and the patient's own reasons for change.