Tools to measure body fat are popular, but do you need them?
Body fat. We need it for insulation and energy. A lot of us have too much of it. A few of us, too little. Finding out just how much fat we have has become easier.
Consumer versions of instruments once used only in bodybuilding gyms, athletic centers and medical centers are now available for use in the privacy of our bedroom or bathroom. The most common devices touted for home use are calipers and bioelectrical impedance analysis machines.
But even the once-inaccessible gold standard of body fat testing — hydrostatic weighing — can be had for $40. At FitnessWave, a Santa Ana, Calif., company that brings mobile testing labs to Southern California health clubs and fitness events, you’re submerged in a big tub of warm water.
But are the results reliable? And, really, do you need to know?
Proponents of body fat testing contend that the weight scale is not an adequate indicator of health and fitness because weight does not tell you how much fat or muscle you have. Two people who weigh 150 pounds each will have different percentages of body fat, depending on a number of factors such as their daily caloric intake, genes and amount of physical activity, including weight-training.
Most people don’t need to have their body fat measured, said Dr. Morris Hasson, medical director of the weight management program at the University of California, Irvine. Body fat testing might come in handy as a tool to track changes in body composition or the results of your fitness efforts, he said. But it’s not necessary for better health and it’s no substitute for a scale for overweight and obese people who need to lose weight.
What’s more, hydrostatic weighing labs aside, the home devices may not be reliable or accurate, he said.
To be sure, body fat measuring tools for home use are appealing because they promise convenience. Pinch the fleshy part of the pelvis with the Accu-Track calipers and you get a measurement in millimeters. Match that number to a chart included with the calipers showing age range and body fat percentage. The more millimeters of fat you pinch, the more body fat you have.
Step onto the Tanita Body Fat Monitor and a digital readout displays your percentage of body fat. Hold the Omron Body Fat Analyzer with both hands in front of you and in seven seconds, you get a body fat reading.
The Tanita and Omron devices use a method called bioelectrical impedance. They send a small electrical signal that travels through the water in your body. The premise is that muscle holds more water and allows the electricity to flow more easily, so the machine measures the fat based on how it resists the signal.
In general, the measurements from home devices are not going to be as accurate as those taken by a trained professional using an institutional-quality machine or instrument at a health club, medical center or college athletic department, Hasson said.
The chances of getting a reliable reading with home bioelectrical impedance machines or calipers are questionable, he said.
Fitness experts agree.
With skin-fold calipers, for example, knowing where and exactly how much skin to pinch requires skill and knowledge, said Amy Keller, performance coach at Intensecity Sports Performance Center in Irvine, Calif. “When I’ve tested athletes, for example, I always pinch in the same area where I got the last measurement and on the same side of the body,” she said. I try to get measurements at the same time as the last one.”
But manufacturers say their devices are quite reliable and accurate.
Tanita’s Web site says its leg-to-leg version of bioelectrical impedance analysis “produces very accurate results that are highly correlated with . . . hydrostatic weighing.” Here’s another example of hype, in the Body Caliper packaging: “The most intelligent, practical instrument available to measure your body composition: the most reliable indicator of true fitness. Now you can measure your body fat quickly and easily — at home — with the same accuracy as fitness professionals.”
As for the value of measuring body fat, that seems subjective.
It’s valuable to Nick Delgado of Irvine, who has his body fat measured using hydrostatic weighing twice a year to monitor his fitness level. “I’ve tried the other methods such as skin calipers, but I wanted the gold standard — it’s the most accurate.” After the holidays, Delgado, 45, had his body fat measured to see if his food indulgence had any effect. Delgado usually sticks to a diet low in fat and high in fruits and vegetables, and exercises regularly.
The results showed little change. Delgado may have gained a pound since he was tested in December, but that gain included nearly equal amounts of fat and muscle.
Body fat testing is not for everyone, UCI’s Hasson said. Its importance depends on your weight and overall health and fitness, he said. “A tremendously overweight person, for example, already knows he or she has a lot of body fat to lose. You don’t need a body fat monitor to tell you that.
“Body fat percentage might be more relevant when you’ve gotten closer to your ideal weight and need to fine-tune.”
That idea seems to apply to Eric Baumgartner, 28, a sales representative in Newport Beach, Calif.
Baumgartner got his body fat measured at the beginning of the year using hydrostatic weighing at FitnessWave. The reason: He had begun a fitness program and wanted to quantify his progress beyond stepping on a scale.
“I was recovering from an injury for a year and stopped working out for a long time,” Baumgartner said. “My weight went up from 190 to 225 pounds. I just started to go to the gym frequently and began to lose weight. I’m trying to eat better and exercise more.”
The proportions of body fat and muscle change depending on what we eat and how much, and what kind of physical activity we do, Hasson said.
