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Clinical Basics

What is BMI? Body Mass Index Definition, Calculation & Health Meaning

Understand Body Mass Index (BMI). Learn what BMI means, how it is calculated, official WHO categories, clinical limitations, and health implications.

What is BMI (Body Mass Index)?

Body Mass Index (BMI) is a standardized mathematical metric used worldwide by clinical practitioners to assess weight relative to height.

WHO BMI Categories

  • Underweight: < 18.5 kg/m²
  • Healthy Weight: 18.5 – 24.9 kg/m²
  • Overweight: 25.0 – 29.9 kg/m²
  • Obesity: ≥ 30.0 kg/m²

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