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This is not a scientific review but rather a brief explanation of measurement techniques and a listing of products available from VacuMed.

Hydrostatic (or underwater) measurements are considered the "Gold Standard" of body fat measurements. Body fat measurements are an important factor in diet and exercise prescription.

Normal range of body fat percentage varies by sex, age and may be influenced by body build, here are some typical values:

Males to age 30 = 8 to 14%, females = 18 to 25%
Males at age 50 = 8 to 17%, females = 18 to 26%

Others have defined normal values for males 12 to 18%,
females 18 to 26%,

Some say the goal for males should be between 12 and 15%,
for females 18 to 22%.

Bio-Impedance Measurements
These electronic body fat analyzers send a minute current through the body and measures the resistance (impedance). When used properly, results are relatively accurate and repeatable. Results are displayed directly in % body fat, so no calculation is required.

More about the accuracy of low-cost Bio-Impedance Devices
Everyone wants to know about accuracy of these devices. It's a tricky question, because the absolute accuracy of all of these body fat analyzers is questionable. The expensive devices use electrodes that are pasted on a hand and a foot. Then there are integrated weighing scales, where the current is passed through the lower body only from one foot to the other. Some hand-held devices pass current through the upper body only from one hand to the other. So you can see that depending on where a person carries the most fat tissue, the various measurement techniques will produce different readings. But we maintain this: What does it matter if your body fat is 27% or 35%. If you are in a fitness program or weight reduction program, what matters is, is my body fat decreasing? Fortunately, even the low-cost "Vitalio" has excellent repeatability to assure that changes are accurately noted.

Skin Fold Measurements
This method utilizes a "Skin fold Caliper" to pinch the skin at several predetermined sites and measure the thickness of that pinch. The results are then summarized and evaluated via several published methods or equations.
These methods are usually based on large population studies, which took skin fold and hydrostatic weighing measurements and then attempt to find equations that manipulate the skin fold measurements so that they match the hydrostatic weighing results.

The reported validity of skin fold measurements is +/-6% at the very best and may be off much more due to several problems with measurement accuracy:

• Inter-operator error, measurements vary widely from technician to technician.
• Technique errors, such as failure to identify the proper measurement site and failure to pinch only fat and no other tissue.
• The underlying assumption that subcutaneous fat represents the same percentage of total fat in every person.
• There are also problems opening skin fold calipers wide enough for very obese persons, resulting in underestimation.

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