Weight loss in children and adolescents

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]

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]

References26Show ledgerHide ledger

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