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UnderNormalOverObese
What Is BMI (Body Mass Index)?
BMI uses height and weight to estimate whether your weight falls in a healthy range — a widely used screening tool, though it doesn't measure body fat directly.
The Formula
Metric: BMI = weight(kg) ÷ [height(m)]². Imperial: BMI = 703 × weight(lb) ÷ [height(in)]²
BMI Categories (WHO)
- Below 18.5: Underweight
- 18.5-24.9: Normal
- 25-29.9: Overweight
- 30+: Obese
Limitations
BMI doesn't distinguish muscle from fat — athletes may show higher BMI despite low body fat.
Frequently Asked Questions
Does the same formula apply to children?
No, children use age- and sex-specific percentile charts instead.
Does higher BMI always mean more fat?
Not necessarily; muscle is denser, so athletic people can have higher BMI with low fat.
Should I rely on BMI alone?
No, combine with waist measurement and a doctor's evaluation.