Monitoring Your Body Fat?
What do you think of body-fat analyzers -- those scales that send an electric current through your tissues to measure body fat? Do you think they're worth the investment?
Your body-fat composition can tell you about your risk of certain diseases, such as heart disease, specific cancers, and type 2 diabetes -- the higher your percentage of body fat, the greater your risk. For many years the "gold standard" for measuring body fat was hydrostatic weighing (you were weighed while submerged under water). However, this test is so cumbersome and expensive that it is used only in academic or research settings. A newer, more reliable, and convenient alternative is dual energy X-ray absorptionetry (DEXA), which uses the same technology for measuring bone density -- but this, too, is available only in medical settings.
The latest entry in body-fat monitors resembles an ordinary bathroom scale -- only this scale can give you a reading of your body-fat percentage as well as your weight. (Click here to see a picture of the scales.) First, you program in some personal data, and then you position your bare feet on metallic foot pads on the scale. Using Bio-Electric Impedance Analysis (BIA), these foot pads send a low electrical signal from one foot to the other. Since fat resists electricity, the device measures resistance to the current. I understand that the measurements are fairly accurate, but the monitors are pricey -- certainly more expensive than most bathroom scales. (Handheld BIA monitors are also available, but they don't measure your weight.) You should be aware that the body-fat analyzer has its limits, including working only on those who weigh less than 300 pounds; it isn't meant for use by professional athletes or bodybuilders; and it can't be used by anyone who has a pacemaker or other internal medical device. To get an accurate reading, you should be well-hydrated. The scale also has to be reprogrammed for every person who uses it (although some models can store data for up to four persons).
For years, the only practical alternative to hydrostatic weighing was the use of calipers. Folds of skin at seven different body sites are measured and then applied to a formula. You'd get an approximation of your body fat, but accuracy depended on the skill and experience of the person doing the measuring. You could have the test done by two different people and come up with totally different results.
That brings us to the question of how closely you want to track your body fat. For good health, the body-fat composition range should be:
For women: from 17 to 24 percent for those under 30; 20 to 27 percent for those over 30.
For men: from 14 to 20 percent for those under 30; 17 to 23 percent for those over 30.
That said, instead of simply paying attention to weight, I think figuring out your body-mass index and waist circumference, and taking into account your family history, is a much better way of gauging your risk for obesity-related diseases.
If you're into high-tech gadgets, and you don't mind forking over between $80 and $180 -- and you think this device can help you manage your weight -- then a BIA body-fat monitor would be a nice toy to have. But most people can get a close enough approximation of whether or not they're too fat from a normal scale, a tape measure, a mirror -- or a favorite pair of jeans.