Body fat analyzers: How accurate are they?

Although the technology is improving, it's difficult to get an accurate body fat measurement from most commercially available body fat analyzers.

Various types of body fat analyzers — also called impedance meters — are available to the general public. Results from portable body fat analyzers can vary depending on many factors, however, including the quality of the device and how hydrated you are when the measurement is taken.

If you're concerned about your body fat percentage, skip the commercially available body fat analyzers and ask your doctor about more accurate measurement techniques.

Depending on the circumstances, options may include:

• Dual energy X-ray absorptiometry. This is a specialized X-ray exam that provides detailed information about the ratio between fat, muscle and bones in specific parts of the body.
• Air displacement plethysmography. With this technique, you're enclosed in a computerized, egg-shaped chamber (Bod Pod, others). The device measures your weight and volume to determine your body density, then uses these figures to calculate your percentage of body fat.
• Underwater weighing. Also known as hydrodensitometry, this method involves sitting on a special chair submerged under water. Your underwater weight or body density is then used to calculate your percentage of body fat.

Body fat can also be estimated using cross-sectional imaging methods such as magnetic resonance imaging (MRI) and computerized tomography (CT) scan. These scans can provide the most precise body composition measurements, especially for intra-abdominal fat measurement. They are expensive, however, and not indicated for everyone.

Depending on the information desired, you and your doctor can determine the optimal type of body fat measurement. Keep in mind that specific body fat measurement techniques can be expensive and may not be available in all locations.