What does BMI classify?

Body Mass Index (BMI) is a widely used measurement that evaluates an individual's body weight relative to their height. It is calculated using the formula weight in kilograms divided by the square of height in meters. By establishing a relationship between height and weight, BMI provides a numerical value that can be categorized to indicate whether an individual is underweight, normal weight, overweight, or obese.

This method does not directly measure body fat percentage or muscle mass, which are often more complex assessments that require different tools or metrics, such as skinfold measurements, bioelectrical impedance analysis, or imaging techniques. Thus, while BMI serves as a useful tool for general health assessments, it is specifically designed to classify body weight in relation to height, rather than focusing solely on height, body fat, or muscle mass.