Paeds · clinical-assessment-and-reasoning
Weight loss in children and adolescents
Also known as Paediatric weight loss · Unintentional weight loss children · Adolescent weight loss · Restrictive eating weight loss · Atypical anorexia
Fellowship diagnostic approach to weight loss in children and adolescents: confirm true loss, quantify severity, threat-first assessment, mechanism-based differential spanning restriction and organic disease, refeeding-aware nutrition restart, and safe disposition.
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Target exams
Red flags
- Polyuria, polydipsia and weight loss — check glucose now for diabetes and DKA risk
- Bradycardia, orthostatic instability, hypothermia or electrolyte abnormality in restrictive eating
- Large percentage loss despite a BMI still labelled ‘normal’ (atypical anorexia pattern)
- Refeeding risk after prolonged poor intake — phosphate, potassium, magnesium
- Fever, night sweats, progressive lymphadenopathy or bone pain with weight loss
- Suicidality, medical instability or failed outpatient care needing admission
Life stages
Care settings
Clinical exam formats
Board mappings
- General and Community Paediatrics
- Growth and nutrition assessment
- Adolescent health
- Renewed curriculum for first-year trainees from 2027 — Learning goal 5: Clinical assessment – essential general paediatrics
- Renewed curriculum for first-year trainees from 2027 — Learning goal 6: Clinical management – essential general paediatrics
- Renewed curriculum for first-year trainees from 2027 — Learning goal 12: Communication with patients, families, and health professionals
- Adolescent medicine, nutrition and mental-health interface competencies
- Clinical Applications
- Adolescent and mental health interfaces
- Long Cases
- Short Cases
- 4. Professional skills and knowledge: Patient management
- 5. Professional skills and knowledge: Health promotion and illness prevention
- General Paediatrics: Assesses growth and nutrition and initiates appropriate management
- Foundation of Practice (FOP)
- Applied Knowledge in Practice (AKP)
- Growth, nutrition, endocrinology and adolescent health
- Clinical
- History
- Communication
- General Pediatrics Content Outline — Domain 1: Preventive Pediatrics/Well-Child Care
- General Pediatrics Content Outline — Domain 11: Nutrition
- General Pediatrics Content Outline — Domain 12: Growth and Endocrinology
- Universal Task 3: Diagnosis
- Universal Task 4: Management and Treatment
- Patient Care 1: History and Physical Examination
- Patient Care 4: Clinical Reasoning
- Patient Care 5: Patient Management
- Interpersonal and Communication Skills 1: Patient- and Family-Centered Communication
- Medical Expert
- Communicator
- Pediatrics: Transition to Discipline EPA #1 — Performing and presenting a basic history and physical examination
- Pediatrics: Foundations EPA — Assessing growth and development
- Pediatrics: Core EPA — Managing common nutritional, endocrine and adolescent presentations
A fourteen-year-old’s jeans are loose. The BMI still sits in the “healthy” band. A nine-year-old has lost three kilograms with thirst and night-time wees. A toddler’s weight is falling because juice replaced meals. These are not the same disease. They share one clinical task: prove that weight really fell, judge danger, and find mechanism before you reassure. [1]
Infant and toddler faltering growth has its own fellowship page. Use that chapter when the problem is slow weight gain or centile crossing in early childhood. This page owns true weight loss and the older-child and adolescent presentations where restriction, diabetes, inflammatory bowel disease and systemic disease dominate the exam list. Technique for weighing and charting lives on the growth-measurement page — borrow the skill; do not re-teach it here. [1]
Weigh and re-plot · Estimate percent from baseline · Instability check (ABCDE, glucose, orthostatics) · Gather intentional vs organic story · Hunt red-flag systems · Triage nutrition, tests and team. [1]
Overview & Definition
Weight loss means the child is lighter than a previously established baseline. That sounds simple until you meet clothes-on weights, different scales, growth spurts, and a BMI chart that still looks “fine.” Fellowship answers start with data quality, then severity, then cause. [1]
Severity is more than today’s BMI percentile. Percentage loss from premorbid weight, speed of decline, and physiological cost (heart rate, blood pressure change on standing, temperature, electrolytes, cognition) tell you who is in danger. Adolescents with atypical anorexia nervosa can lose a large fraction of body weight and still land in a numerically normal BMI band. The band does not cancel the loss. [1]
Intentional versus unintentional is a framing question, not a final label. Intentional pathways include restriction, purging, driven exercise and body-image fear. Unintentional pathways include new diabetes, malabsorption, inflammatory bowel disease, thyrotoxicosis, chronic infection, malignancy and food insecurity. Mixed pictures are common: a child with Crohn disease may also restrict because food triggers pain. Keep both doors open until the story closes them. [1]
Cachexia is not pure starvation. Evans and colleagues defined cachexia as a complex metabolic syndrome with loss of muscle, with or without fat loss, often driven by inflammation and illness. In a child with cancer or advanced chronic disease the plan is not “just eat more” alone. [21]
References26ShowHide
- [1]Hornberger LL Identification and Management of Eating Disorders in Children and Adolescents. Pediatrics, 2021.PMID 33386343
- [2]Society for Adolescent Health and Medicine Medical Management of Restrictive Eating Disorders in Adolescents and Young Adults. The Journal of adolescent health : official publication of the Society for Adolescent Medicine, 2022.PMID 36058805
- [3]Golden NH, Katzman DK, Sawyer SM, et al. Position Paper of the Society for Adolescent Health and Medicine: medical management of restrictive eating disorders in adolescents and young adults. The Journal of adolescent health : official publication of the Society for Adolescent Medicine, 2015.PMID 25530605
- [4]Trapani S Medical Complications of Anorexia Nervosa. Pediatrics, 2025.PMID 40659363
- [5]Robatto AP Diagnosis and treatment of eating disorders in children and adolescents. Jornal de pediatria, 2024.PMID 38158193
- [6]Kambanis PE Assessment and Treatment of Avoidant/Restrictive Food Intake Disorder. Current psychiatry reports, 2023.PMID 36640211
- [7]Veauthier B Diabetic Ketoacidosis: Evaluation and Treatment. American family physician, 2024.PMID 39556629
- [8]Kostopoulou E Diabetic Ketoacidosis in Children and Adolescents; Diagnostic and Therapeutic Pitfalls. Diagnostics (Basel, Switzerland), 2023.PMID 37568965
- [9]Ziegler R Diabetes in Childhood and Adolescence. Deutsches Arzteblatt international, 2018.PMID 29563012
- [10]Rosen MJ Inflammatory Bowel Disease in Children and Adolescents. JAMA pediatrics, 2015.PMID 26414706
- [11]Ishige T Growth failure in pediatric onset inflammatory bowel disease: mechanisms, epidemiology, and management. Translational pediatrics, 2019.PMID 30881894
- [12]Veauthier B Crohn's Disease: Diagnosis and Management. American family physician, 2018.PMID 30485038
- [13]Riznik P Clinical Presentation in Children With Coeliac Disease in Central Europe. Journal of pediatric gastroenterology and nutrition, 2021.PMID 33306584
- [14]Al-Toma A European Society for the Study of Coeliac Disease (ESsCD) guideline for coeliac disease and other gluten-related disorders. United European gastroenterology journal, 2019.PMID 31210940
- [15]Vaidyanathan P Update on Pediatric Hyperthyroidism. Advances in pediatrics, 2022.PMID 35985711
- [16]da Silva JSV ASPEN Consensus Recommendations for Refeeding Syndrome. Nutrition in clinical practice : official publication of the American Society for Parenteral and Enteral Nutrition, 2020.PMID 32115791
- [17]Garber AK A systematic review of approaches to refeeding in patients with anorexia nervosa. The International journal of eating disorders, 2016.PMID 26661289
- [18]Harrington BC Initial evaluation, diagnosis, and treatment of anorexia nervosa and bulimia nervosa. American family physician, 2015.PMID 25591200
- [19]Homan GJ Failure to Thrive: A Practical Guide. American family physician, 2016.PMID 27548594
- [20]Gonzalez-Viana E Faltering growth in children: summary of NICE guidance. BMJ (Clinical research ed.), 2017.PMID 28963099
- [21]Evans WJ Cachexia: a new definition. Clinical nutrition (Edinburgh, Scotland), 2008.PMID 18718696
- [22]Białek-Dratwa A ARFID-Strategies for Dietary Management in Children. Nutrients, 2022.PMID 35565707
- [23]Bohon C United States-based practice guidelines for children and adolescents with eating disorders : Synthesis of clinical practice guidelines. Journal of eating disorders, 2025.PMID 40217324
- [24]Kerem NC Respiratory acidosis in adolescents with anorexia nervosa hospitalized for medical stabilization: a retrospective study. The International journal of eating disorders, 2012.PMID 21321988
- [25]Shields B Weight faltering and failure to thrive in infancy and early childhood. BMJ (Clinical research ed.), 2012.PMID 23014901
- [26]Harper NS Neglect: failure to thrive and obesity. Pediatric clinics of North America, 2014.PMID 25242707