How is BMI calculated and what does it indicate?

The calculation of Body Mass Index (BMI) correctly involves taking a person's weight in kilograms and dividing it by their height in meters squared. This formula allows for a straightforward assessment that correlates an individual's weight to their height. BMI is primarily used as a screening tool to categorize individuals based on whether they are underweight, normal weight, overweight, or obese. These categories are instrumental in indicating potential health risks associated with body weight, including obesity-related conditions such as diabetes, heart disease, and hypertension.

While other options mention different formulas and health indicators, they do not accurately represent the standard calculation or the primary purpose of BMI. For example, the second option misstates the formula by reversing the variables, while the third incorrectly relates BMI to waist circumference, and the last suggests a formula unrelated to BMI assessing metabolic rate. Thus, the correct choice not only presents the accurate formula for BMI but also highlights its significance in evaluating health risks related to body weight.