HealthKick: How Much “Weight” Should you Give Your BMI?

“BMI” stands for “body mass index,” a calculation used to compare your weight to your height. Traditionally, it has been used to determine a person’s need to lose weight. But what does the BMI calculation really mean? Your BMI is one of several measures that you can use to evaluate your weight appropriateness, but only in general terms.

Your BMI is your weight (in kilograms) divided by your height (in cm) squared (times itself). Using pounds and inches, you can multiply your weight by 703 and then divide by your height in inches squared. A BMI between 20 and 25 is considered healthy.

The limitation of this calculation is that is says nothing about your lean body mass (LBM), the composition of your weight, and how fit you are. You can have a BMI in the perfect range, but be unfit because your weight is composed of fat rather than LBM. Or you can have a BMI well above 25 but be perfectly healthy due to being muscular. More specialized measurement techniques and tools are needed to determine a person’s LBM.

BMI also does not show where your body is “holding” your weight. This is significant because weight carried along the trunk of your body (through the torso/belly) has a much higher health risk than the same weight carried in the hip area. For this reason, new alternatives have been proposed which attempt to evaluate these variables as well. They are:
1. Measuring your waist. Measure your waist at its narrowest point. For women, maximum waist size should be 35 inches, for men, 40 inches. (Keep in mind that these values are for health risk prevention rather than optimal health.) Your waist should always be less than half your height.
2. Waist-to-hip ratio. After measuring your waist, measure you hips at their widest point. Divide the waist measurement by the hip measurement. The goal for this measurement is to be under .8 for women and .9 for men.

All of these measurements are simply numbers. They are used by scientists to track diseases and make predictions. They should not be used by individuals to determine health status or fitness level. You can certainly use them to give yourself an objective look at your weight and body shape and to track changes and effects of your Martial Arts training, but don’t view them as absolute rules.