What does body mass index (BMI) measure?

Body mass index (BMI) specifically measures body fat based on an individual's height and weight. It provides a numerical value that helps categorize individuals into weight categories such as underweight, normal weight, overweight, or obese. BMI is calculated by dividing a person's weight in kilograms by the square of their height in meters. This measurement is widely used because it is a quick and simple method for assessing whether a person has a healthy body weight for a given height.

Unlike assessments of cardiovascular endurance or overall fitness levels, which require different types of evaluations and testing protocols, BMI is solely concerned with weight relative to height. While BMI does not directly measure body fat percentage and can be affected by factors like muscle mass (as in athletes), it remains a useful screening tool for identifying potential health risks associated with being underweight or overweight.

The other choices relate to fitness components that require different assessments. Cardiovascular endurance measures aerobic fitness, muscle density and strength relate to muscular development, and overall fitness level encompasses multiple aspects of physical health, including but not limited to, strength, endurance, flexibility, and body composition.