Understanding Body Fat Analysis

By Gail Sas
There is growing evidence that clearly links body composition with health risks and development of certain diseases.  New research indicates that fat loss, not weight loss, can extend human longevity.

By measuring body composition rather then relying on the bathroom scale, a person’s health status can be more accurately assessed and the effects of both dietary and physical activity programs can be better adjusted!  The bathroom scale shows the sum total of our body’s contents (bones, organs, body fluids, skin, hair, muscles, etc.) even the weight of the food you ate at your last meal.  Not to mention our fluid retention!  

Most people don’t realize that there is only one “direct” method of measuring body composition that is close to 100% accurate.  Unfortunately that is through an autopsy performed Post Mortem!  Obviously that provides no purpose while we are alive!  Other current methods for measuring body composition rely on “indirect” measurement called “In Vivo” methods, meaning on a living body.  

“In Vivo” methods give estimates of percentage of fat-free mass, muscle, bone density, hydration, or other body components.  Each method uses one or more measureable body component (such as skinfold thickness, resistance, etc.) to make educated predictions about the other components.  These predictions are based on years of research that define statistical relationships between different body components.

Currently, no trial data exist to indicate that one method of measuring body fat is better than any other for following overweight and obese patients during treatment.  Good results depend upon taking accurate measurements and an adequate, scientifically derived database.  Every measurement method has strengths as well as definite sources of error.  Most research studies employ several methods used in combination.

Body composition equipment manufacturers should have scientific studies available to support accuracy claims, but often companies fail to explain the problems encountered in day-to-day use outside the controlled environment of a research lab.

While all methods of measuring body fat contain a margin for error the one that provides the most accurate reading is known as underwater weighing.  This method is considered to be the “gold standard” of all other methods.  This method measures whole body volume.  While not easy to perform on the first time, you are given time to practice! The participant is to sit on a bench that is attached to a scale above it.  This bench is in a large tank of water.  The participant is told to fully sink

under the water.  While doing so the participant needs to blow out all air while submerged.  It is very necessary that the participant is to hold still in the process so that the indicator on the scale shows a steady number.  The densities of bone and muscles are higher than water, and fat is less dense than water.  So a person with more bone and muscle, meaning they have a higher bone density this indicates a lower percentage of body fat.   Two local universities provide this procedure for a minimal fee.

The next most reliable tool is a rather new technology known as the “Bod Pod.”  This unit is provided  local universities.  Air displacement is used to measure body volume automatically.  Measurement time takes roughly five to eight minutes per individual.  More comfortable then underwater weighing.

Other methods of evaluating body fat percentages can be provided by tools known as calipers, near-infrared body composition analysis, and bioelectrical analysis.  There are new in-home scales available in department stores that evaluate your weight, hydration levels and over all body weight, all methods provide an estimate.  The easiest approach should still be how your clothes fit, and the use of a tape measure!