Measuring Obesity, Overweight and Lean Body Tissue

Last time I wrote about the confusion of various words used to describe body fatness. Here, I’ll briefly define some of the procedures used to determine or estimate body fat.

Body Mass Index (BMI) scores – A number calculated from a person’s height and weight via a formula. This number indicates desirable and non desirable level of weight. Not an accurate measure of body fatness.

Anthropometric measurements – Series of body part measurements including height, weight, skin folds and circumferences/lengths of selected body parts. Used to estimate overweight/obesity status.

Skin fold measurements – Using a specialized caliper, the amount of body fat is estimated. Skin fold thicknesses are taken on various (1 to 9) body sites. Using these data, percentage of body fat is provided.

Waist-to-Hip ratio – Waist and hip circumferences are measured at specific locations. People with a disproportionate waist size compared to hip size are considered an “apple” shape and are more prone to certain diseases.

Underwater Weighing – The weight of a person under water compared to a person’s weight outside of water compared. Lung volumes are also measured. A formula is applied to these data and body fat is determined.

Bioelectrical Analysis (BIA) – Body fat testing is based upon the flow of electrical current through the body tissues. The data are then used to estimate fat-free weight and ultimately body fat.

DEXA Scanning (Dual Energy X-Ray Absorptiometry) – When used for body composition a 3 compartment model divides the body into total body mineral, fat-free lean tissue and fat tissue mass.

Air Displacement Plethysmography (Bod Pod) – Using the same principal as underwater weighing computer sensors measure the amount of air displaced when sitting in a capsule. Calculations determine body fat.

Other – Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and Near Infrared Interactance (NIR) are also used.

Next time, I’ll address one or more in greater detail.

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