Body Mass Index (BMI)

Definition

Body Mass Index (BMI) is a numerical value derived from an individual's weight and height, commonly used to classify underweight, normal weight, overweight, and obesity.

Scientific / Technical Definition

Body Mass Index (BMI) is calculated as a person's weight in kilograms divided by the square of their height in meters (kg/m²). It provides a simple numeric measure of a person's thickness or thinness, which can help evaluate whether they are underweight, normal weight, overweight, or obese.

Benefits

• Helps in assessing whether a person is underweight, normal weight, overweight, or obese.
• Provides a quick and easy way to screen for weight categories that may lead to health problems.
• Used to monitor population-level weight status and trends.

Examples

• A BMI of 18.5 to 24.9 is considered normal.
• A BMI under 18.5 indicates underweight.
• A BMI of 25 to 29.9 indicates overweight.
• A BMI of 30 or above indicates obesity.

Additional Information

• Known issues: BMI does not account for muscle mass, bone density, overall body composition, and racial and sex differences. Thus, it may misclassify muscular individuals as overweight or obese.

Related Terms

• Waist-to-hip ratio
• Basal metabolic rate (BMR)
• Caloric intake

References

• Body Mass Index (BMI) - Centers for Disease Control and Prevention
• The Clinical Use of Body Mass Index (BMI) - NCBI