Bathroom Scales Don't Tell The Whole Story
Experts rate the best and worst in body-fat measurement devices.
Body Fat-Measuring Scales
"Bioelectrical impedance analysis" has been added to traditional
bathroom scales. The scales send a harmless electrical current up through your
body to "read" the amount of fat body mass and lean body mass --
calculating your percentage of body fat.
Price: $50 to $100 per scale.
The verdict: Convenient, but not always the most
"The problem is, these devices are very sensitive to hydration -- how
much fluid is in your body," Bryant tells WebMD. So it's important to
strictly follow the guidelines for weighing yourself -- time of day, fluid and
food intake. Even your menstrual cycle affects this reading. "However, with
all this factored in, the scales are an easy, at-home way to keep track of your
weight and fat-loss progress."
There also are handheld versions that use this same technology. Just
remember: You get what you pay for. Higher price equals greater accuracy.
Grade: C+. "Even though they may not be accurate, it
may be good for tracking changes with a diet and exercise program," says
McCrory. "Just keep in mind that the scales might be off by 5%, plus or
minus. Follow the instructions carefully. Taking a shower beforehand really
makes the reading inaccurate!"
DEXA is "dual energy X-ray absorpitometry" -- the same imaging
technology doctors use to measure bone density to determine osteoporosis risk,
explains Bryant. During the test, you lie on an X-ray table for about 10
minutes while the scanner measures your body fat, muscle, and bone mineral
Price: $200 to $300
The verdict: Looking good.
DEXA is "an emerging technique that holds a lot of promise," Bryant
tells WebMD. "It allows us to determine the amount of body fat overall, and
to identify fat deposits in specific body regions. That's very important,
because stores of body fat can be much more indicative of disease risk."
For example, extra abdominal fat increases the risk of heart disease, cancer,
and type 2 diabetes.
Primary-care doctors, physical therapists, and health clubs will soon be
offering DEXA scanning to assess body fat, Bryant tells WebMD. "If your BMI
says you're in the obese category and you have a strong family history of heart
disease and diabetes, it might behoove you to get more precise assessment of
body composition," says Bryant.
Grade: A. "It's one of the most accurate methods out
there," says McCrory. "I haven't heard any news about DEXA in health
clubs. But if you have the opportunity to be tested by DEXA, go for it."
She warns, however, that obese people may have a hard time lying on the narrow
tables used for this test.
It's "quite noninvasive," says Kravitz. "Very good