Know Your Numbers: Body Mass Index and Waist-to-Hip Ratio
Two measurements are frequently thrown around by health and fitness professionals, in popular magazines, in the news, and on-line. They are Body Mass Index and Waist-to-Hip Ratio. But do you know what they really mean, and even more importantly, do you know what yours are?
Your Body Mass Index, or BMI, is the ratio of your height divided by your weight squared, and is used to determine if you are underweight, of normal weight, or overweight.
BMI = your weight (in kg) ÷ your height2 (in m)
If your BMI is below 18.4, then you are considered underweight. Between 18.5 – 24.9 is the normal range. And anything above 25 is considered overweight, with numbers above 30 being significantly overweight.
This measurement has one major pitfall: it doesn't take into account a person's body fat percentage. As a result, a very fit and muscular person could find him or herself classified as overweight which would be inaccurate (remember, muscle weighs more than fat by volume). Nevertheless, for most of us in the general population this number gives us a pretty good picture of where we stand.
Your Waist-to-Hip Ratio tells you a lot about how fat is distributed throughout your body. People with a high ratio are said to have an apple shaped body (more fat around the middle, thus appearing a bit rounder overall), while those with a lower ratio have a pear shaped body (slightly more bottom-heavy). It turns out that apples tend to have a higher risk of developing high blood pressure, type II diabetes, and high cholesterol.
To determine your ratio have someone measure your waist at its smallest circumference between your ribs and belly button, and your hips at their greatest circumference between your hip bones and buttocks. Then divide the waist measurement by the hip measurement.Continued on the next page