In what unit should BMI be calculated to determine if a child is overweight or obese?

Body Mass Index (BMI) is a widely used method for assessing whether an individual has a healthy body weight for their height. The formula for calculating BMI is weight in kilograms divided by height in meters squared (kg/m²). This unit of measurement is standardized and provides a consistent way to evaluate weight status across different populations.

Using kg/m² allows for a straightforward interpretation of BMI values, making it easier to categorize children into weight classes, such as underweight, normal weight, overweight, or obese. Authorities like the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) utilize this metric due to its reliability and straightforward applicability in various clinical and health settings.

Other options do not conform to the standardized measure of BMI. For instance, using total body weight divided by height does not account for the necessary square of height, leading to inaccurate results. The method using pounds and inches lacks the universally accepted metric of kg/m² and does not facilitate consistent comparisons across different populations. Lastly, calculating height in centimeters and weight in grams does not align with the conventional BMI formula, as it does not form the necessary unit of kg/m².

Therefore, the correct unit for calculating BMI, particularly for assessing weight categories in children, is