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What is Body Mass Index (BMI)?

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Understanding BMI

Body Mass Index (BMI) is a person's weight in kilograms divided by the square of height in meters. It is an inexpensive and easy screening method for weight category—underweight, healthy weight, overweight, and obesity.

BMI Categories

  • Underweight: < 18.5
  • Normal weight: 18.5 – 24.9
  • Overweight: 25 – 29.9
  • Obesity: 30 or greater

Limitations

BMI does not measure body fat directly. As such, some people, such as athletes, may have a BMI that identifies them as overweight even though they do not have excess body fat.