Back Clinic Basal Metabolic Index (BMI) Functional Medicine and Fitness Team. BMI or Body Mass Index is a statistical measure that compares a person’s height and weight to determine their overall body composition and fat. If the BMI classification is beyond normal, it is considered a progressively increasing risk of cardiovascular disease. Although BMI doesn’t measure body fat directly, it uses weight and height to determine whether an individual is classified as underweight, normal weight, overweight or obese.

BMI is measured by dividing your weight in pounds by the square of your height in inches, then multiplying by 703. The equation looks like this: BMI = (weight / height x height) x 703.

For example if an individual is 125 pounds and 5 feet 4 inches, then the BMI = (125 / 64 x 64) x 703 = 21.4. This BMI puts the individual in the normal weight range.

This measurement correlates moderately well with other body fat measurements, such as skinfold measurements and underwater weighing. This is according to the Centers for Disease Control and Prevention.