Body mass index (BMI) is a person’s weight in kilograms divided by the square of height in meters. BMI is an inexpensive and easy screening method for weight category- underweight, healthy weight, overweight, and obesity. BMI does not measure body fat directly, but BMI is moderately correlated with more direct measures of body fat. Furthermore, BMI appears to be as strongly correlated with various metabolic and disease outcome as are these more direct measures of body fatness
BMI can be a screening tool, but it does not diagnose the body fatness or health of an individual. To determine if BMI is a health risk, a healthcare provider performs further assessments. Such assessments include skinfold thickness measurements, evaluations of diet, physical activity, and family history.