Body mass index, BMI, body mass index calculator, BMI calculator The Body Mass Index, or BMI, clarifies an important distinction between overweight and obesity. If you weigh too much, you are obviously overweight. But if you have a very high proportion of body fat, you are obese. Depending on your body mass index, your doctor or other health professional will rate your weight as being healthy, overweight or obese. According to the National Heart, Lung and Blood Institute (NHLBI), BMI "describes body weight in relation to height and correlates with total body fat content in most adults". In almost all cases, this means that BMI will accurately reflect your weight and body fat proportion based on your height and weight when categorized as being healthy, overweight or obese. Calculating your approximate body mass index is relatively simple, although you will probably need a calculator just to save time. To get your BMI, multiply your weight in pounds by 703. Then, divide...