Although most doctors use BMI (Body Mass Index) for measuring how physically fit a patient is, it is not the most reliable indicator of how healthy you actually are. According to Runner’s World, “healthy BMI ranges are quite large (a 5’4″ woman could weigh anywhere from 108 to 145 lbs and still be in an acceptable range), so it’s only useful if you’re significantly over- or underweight. And the formula doesn’t hold up with very muscular athletes. A 5’10” 209-lb man, for example, with just 10 percent body fat is actually considered overweight by BMI standards.”
BMI does not take factors such as body frame, body fat, or muscularity into account and therefore cannot give an accurate measure of your overall fitness. At home body fat scales are not much better. Your hydration level, the time of day, and even the room temperature can affect the accuracy of these devices.
So what is the best way to measure your progress? If you are lifting weights or doing other resistance exercises, you may not notice a change on the scale, or you may even gain weight due to an increase in muscle. This is not a bad thing! For every pound of muscle you build, you are increasing your caloric burn by about 5o calories per day. Body fat calipers are the best way to go when it comes to measuring body fat percentage for a fairly inexpensive cost. Just be sure that the person doing the measuring (you shouldn’t measure your own body fat because it won’t be as accurate) is consistent in the way they are taking the measurements. Levels for fit athletes range from about five percent to 17 percent for men and 13 percent to 24 percent for women.
Lastly, a tape measure can also be a good gauge of how you are progressing, especially with resistance training. Often, my clients will see changes in their measurements before they see the scale go down. Remember, nobody else sees the number on the scale, but they can see your waistline!
“Weight Loss by the Numbers.” M. Nicole Nazzaro. Runner’s World, November 2009