An important component of starting a fitness or weight loss program is knowing your starting point.  As a fitness professional, one of my fundamental responsibilities is to do a thorough screening of each client.  Body fat is one of the many important bits of data I collect during my screening.  In this blog entry I will give a brief explanation of three popular methods of measuring body fat. 

 

Hydrostatic weighing (water displacement), bio-electrical impedance and skin-fold (caliper) are currently the most popular methods of measuring body fat.

 

Hydrostatic weighing is the most accurate method.  However, the necessary equipment can fill a room.  Simply put, it involves immersing the whole body in water and determining body fat by the amount of water displaced.  Due to cost and equipment needs this method is limited a lab, medical or research facilities.

 

The Skin-fold (caliper) method ranks second in accuracy.  The equipment is minimal and very inexpensive.  Some basic training is recommended but most people can perform this method after reading the instructions and a little practice.  The margin for error of roughly 4% (plus/minus).  The downside of this method is that it can be intrusive.  It requires a gentle "pinch" of different areas of the body.

 

Bio-electrical impedance is the fastest but least accurate method.  This method uses a hand held device.  There are numerous manufacturers and model that fall under this category. The basic science involved is sending a harmless, electronic signal through the body.  The amount of time the signal takes to pass throughthe body goes into calculating body fat.  The accuracy of this method varies greatly depending upon the equipment manufacturer, hydration levels, sex, body type.  I find this method very inaccurate for people who are either very lean or very obese.