Weight Scales Don't Tell The Whole Story (cont.)It's "quite noninvasive," says Kravitz. "Very good technique." Also called hydrodensitometry testing, this involves getting into a tank filled with water. Based on the amount of water you displace, your body density and body fat can be calculated. "This test is considered the gold standard, the most accurate assessment technique," Bryant tells WebMD. Universities use this primarily with athletes, and will likely let you try it, too -- for a small fee. Price: $25 to $75 per test. The verdict: "It's a very accurate way to measure body fat," says Bryant. But going into the water can be a problem. Some find the procedure "disconcerting." Grade: B-. Inconvenience is a big issue here, agrees McCrory. "My guess is that underwater testing will be a 'has been' in a few years." Bod Pod The Bod Pod is a new tool that relies on air displacement to determine body fat, says Bryant. There's no submersion; you don't get wet. But you have to get into the Bod Pod chamber, be very still, control your breath all factors that can affect the results. Your hydration level before the test can also affect results. "When all these are controlled pretty well, you'll get a body fat calculation that's within 3% to 4% accurate not as high as one might expect," Bryant says. Price: $40 to $65 per test. The verdict: McCrory says she believes it may be the way of the future, though Bryant notes that it needs some refinement. Grade: A. "It's much easier and more convenient than underwater weighing," says McCrory. "It is about as accurate and reliable as DEXA, is much cheaper, and is becoming more widely available." The Tape Measure It's one of the oldest "obesity tests" known to mankind. However, waist circumference in this context "is not defined as a seamstress would," says Bryant. "This is taken at the belly button level." Men with measurements higher than 40, or women with waist measurements higher than 35, are considered obese, he says. Price: None. The verdict: This is a basic indicator of a body fat problem, says Bryant. "It's a good technique," says Kravitz. Grade: A. Girth measurement is "accurate and reliable" for assessing your risk of chronic diseases like diabetes, heart disease, stroke, and cancer, says McCrory. Quite simply: The bigger the girth, the bigger the risk. "However, some new research is coming out suggesting that there is more risk than previously thought at even lower risk circumferences." Skinfold Calipers Health clubs offer this test; it's the most widely used method for measuring body fat, says Bryant. Basically, it's a "pinch" test using a measuring device at several points on the body, like thighs, hips, and upper arm. Price: $20 to $40 per test. The verdict: Much depends on the skills of the person giving you the test. "The skinfold test can be reasonably accurate," Bryant tells WebMD. "But if the tester isn't experienced, or if they're using cheapo plastic calipers, take it with a grain of salt. It will be terribly unreliable." Grade: D. "These are rarely done correctly," says McCrory. "The technician usually does not grab enough fat so the result is usually a big underestimate of body fat. It's also difficult to grab the fat consistently." Infrared Light Measuring Infrared light measuring is an inexpensive way to measure body fat with a soil-analysis-type device that agronomists use, Bryant explains. Here's what happens: A probe is placed on a body site -- the biceps, for instance -- sending an infrared light ray through both fat and muscle. Your height, weight, sex, age, frame size, and activity level are factored in. The final number is a "rough estimate" of your body fat percentage, says Bryant. Price: $25 to $50 per test. The verdict: "It hasn't proven to be terribly accurate," Bryant tells WebMD. Grade: F. Don't waste your time or money, says McCrory. Height/Weight Charts These are the simple height-vs.-weight tables used for years by many insurance companies. But the experts say they just don't work very well, even if they take body frame and sex into account. Price: None. The verdict: "These charts have significant limitations," says Bryant. "They really aren't measuring fat-to-lean tissue. They are based on a limited sample of the population and can be misleading." Grade: F. "These do nothing to help us understand body composition," Kravitz says. Originally published March 19, 2004 SOURCES: Cedric X. Bryant, PhD, chief exercise physiologist, American Council on Exercise. Megan McCrory, PhD, energy metabolism scientist, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston. Len Kravitz, PhD, senior exercise physiologist, IDEA. Last Editorial Review: 8/8/2005 1:05:48 PM © 2005-2013 WebMD, LLC. All rights reserved. |
Women's Health Newsletter
Sign up to stay informed with the latest women's health-related updates on MedicineNet delivered to your inbox FREE!
BONUS! Get a Free PDF Women's Health Report when you sign up!
