Body mass index (BMI)

Body mass index (BMI) is a value derived from the mass (weight) and height of a person. The BMI is defined as the body mass divided by the square of the body height, and is universally expressed in units of kg/m², resulting from mass in kilograms and height in metres.

Calculation

The BMI is calculated by dividing an individual's weight in kilograms by the square of their height in meters. The formula is:

BMI = weight (kg) / (height (m))^2

For example, if a person weighs 70 kg and is 1.75 m tall, the calculation would be:

BMI = 70 / (1.75)^2 = 22.86

Categories

The World Health Organization (WHO) has established standard categories for BMI:

• Underweight: BMI less than 18.5
• Normal weight: BMI 18.5–24.9
• Overweight: BMI 25–29.9
• Obesity: BMI 30 or greater

These categories help healthcare professionals to identify potential health risks related to body weight.

Limitations

While the BMI is a useful tool, it has its limitations. It does not directly measure body fat, and it does not account for muscle mass, bone density, overall body composition, and racial and sex differences. Therefore, it should be used as a general guide rather than a definitive indicator of body fatness.

See also

• Obesity
• Overweight
• Underweight
• Body fat percentage

References

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