Overview
Determining your ideal body weight is more complicated than it may seem. Height and weight tables have traditionally been used, but now body mass index (BMI) is the gold standard for determining whether your weight is too high, too low or ideal, according to exercise scientists Jack Wilmore, David Costill and Larry Kenney. However, even BMI has limitations. Therefore, you should also consider your waist circumference and body fat percentage when figuring your ideal weight.
Height and Weight Tables
According to Dr. Steven Halls, Metropolitan Life Insurance Company introduced height and weight tables in 1943. These tables estimate your ideal weight range based on your height and body frame. For example, according to the table, if you are 6 feet tall with a “medium frame,” you should weigh between 157 and 170 pounds. While these tables may accurately predict your ideal weight, Halls does not recommend using these tables because they are not accurate for very short and very tall individuals.
Body Mass Index
BMI is a better weight classification system than height and weight tables because it more accurately accounts for your stature. To calculate your BMI, divide your weight in pounds by your height in inches squared and then multiply by a conversion factor of 703. For example, if you weigh 220 pounds and are 72 inches tall, your BMI is 29.8 (220 ÷ 5184 X 703 = 29.8).
BMI calculations are divided into five categories. You are “underweight” if your BMI is less than 18.5, “normal” between 18.5 and 24.9, “overweight” between 25.0 and 29.9, “obese” between 30.0 and 39.9 and “extremely obese” if your BMI is 40.0 or more. While BMI is preferable to height and weight tables, it is not perfect. If you are muscular, you may classify as overweight or obese when, in fact, your weight is fine.
Waist Circumference
If you believe your BMI inaccurately classifies your ideal weight, you can measure your waist circumference to investigate further. To measure your waist circumference, wrap measuring tape around your waist at the height of your navel. If your BMI is 30.0 or more and your waist circumference is greater than 40 inches, you should definitely try to lose weight. However, if your waist circumference measures less than 40 inches, you should measure your body fat percentage for the final verdict.
Body Fat Percentage
You can use various techniques to measure your body fat percentage. According to Wilmore, Costill and Kenney, the most accurate is underwater weighing, but this is complicated–it requires sophisticated equipment and a professional trained to use the equipment. A more practical technique involves measuring your skinfold fat thickness at various locations on your body, but these measurements are not as reliable. Nevertheless, an accurate measure of your body fat percentage provides the final piece of the puzzle for calculating your ideal body weight. According to Wilmore, Costill and Kenney, your body weight is fine if your body fat percentage is less than 20 percent.
Changing Your Weight
If you are overweight or underweight, you should take steps to move your BMI into the normal range. If you need to lose weight, you should begin burning more calories than your consume. You can do this by exercising more, eating less or a combination of these. Conversely, if you are underweight, you need to consume more calories than you burn. You should also consider starting a resistance training program if you are underweight to build more muscle mass.
About this Author
Matthew Schirm has worked in the sports performance field for 10 years. He has professional experience as a baseball coach and weight training instructor. He recently earned a Master of Science degree in human movement from A.T. Still University in Mesa, Ariz.
