Types of Body Composition Testing Available
Health is Not Solely Defined by Weight, but by Overall Composition
Feb 7, 2009
There are multiple ways today to test body composition in order to define body fat percentage. The following methods of defining body fat percentage are highly accurate and scientific, but less convenient, less accessible, and more expensive than other methods.
Bod Pod
The Bod Pod is an extremely expensive test that uses computerized sensors to measure the amount of air displaced while a person sits in a capsule. A calculation is then applied to determine body density and then estimate body fat.
Computed Tomography
This test produces cross-sectional scans of a body. The CT scanner is a large machine with a tunnel in the center. An x-ray tube sends a beam of photons towards a detector as it rotates around the body. Data is collected and applied to algorithms that build images determining body composition. There is a risk of radiation exposure with this test, and the equipment is very expensive.
Dual Energy X-ray Absorptiometry
This test is based on bone mineral content being directly proportional to the amount of photon energy absorbed, according to the new-fitness.com article "Body Fat Analyzing - Comparing Methods for Measuring Body Fat." The DEXA test divides the body into total body mineral, lean soft mass, and fat tissue. The test uses a body scanner with two low-dose x-rays at different locations simultaneously reading bone and soft tissue mass. The scanner passes over the body collecting data at .5 intervals. This test is quickly becoming a competitor to underwater weighing in being one of the most accurate. It provides a higher degree of precision in only one measurement and can pinpoint where fat is distributed in the body. The downside is that it is not as accurate measuring the extremely obese.
Magnetic Resonance Imaging
An MRI test uses a magnetic field to stir up water and fat molecules in the body, which produces a measurable signal. This test scans a body lying within the magnetic field, and then produces images that display the amount of fat and where it is. There is no exposure to ionizing radiation, but the equipment and the resulting analysis is very expensive.
Near Infrared Interactance
NIR is based on studies that show optical densities are linearly related to subcutaneous and total body fat, according to the new-fitness.com article. The test indirectly measures fat and water at a point on the body (usually the bicep) using a fiber optic probe connected to a digital analyzer. The light goes through the tissues and bounces off the bone back to the digital analyzer. The data collected is used in an equation that includes age, height, weight, sex, frame size, and level of activity to estimate body fat. Factors to consider when performing the test include the amount of pressure applied using the probe as that may affect the values, as well as considering skin color and levels of hydration. Accuracy declines when measuring the very lean or very obese.
Total Body Electrical Conductivity
The TBEC test is based on the idea that lean tissue is a better conductor of electricity than fat. The test requires a person to lay in a tube that generates a weak electromagnetic field. The field strength depends on the electrolytes found in the body water. Ten readings are required to estimate the lean body mass.
These testing methods are some of the latest in technology. What is new and expensive today, may be converted to an affordable test a person can do at home tomorrow.
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