Body mass index, otherwise known as BMI, allows you to quickly compare your weight to the healthy weight range for your height. It allows you to judge your relative “fatness”, so to speak. However, there are many other “high-tech” methods available that will allow you to determine how much fat you have. The amount you have on your body is generally referred to as “percent body fat”.
You may have read about some of these methods in various magazines and books or you may have heard them talked about in various health clubs you have frequented. This article will review one specific high tech method, called Underwater Weighing.
Underwater weighing is probably the most accurate method of determining your percent body fat. However, underwater weighing is also the most impractical because it’s done with very sophisticated equipment normally found only at university research facilities. This method relies on the premise that fat floats, similar to how oil floats on top of water. Based on this, you can determine how much of your body is lean and how much is fat by submerging it in a large tub of water.
To determine your percent body fat using this method, you sit in a large tub of water in a special chair. A trained technician will then submerge you completely underwater for about twenty seconds. You must force all air out of your lungs during this time as well. While underwater, the technician weighs you. This is repeated ten times to get an average.
To get your body’s volume, the technician will calculate the difference between your body’s weigh in the water and on land. The technician will then do some mathematical calculations to obtain your percent body fat.