Feign interest in joining the climate-controlled confines of your local health club, and you'll soon be snowed under by a blizzard of value-added incentives. A complimentary session with a personal trainer. Logo-emblazoned fanny pack. Even a free body-fat test. Our advice? Opt for the trainer and skip the test — it won't tell you much.
That is, at least not according to a study of 16 competitive bodybuilders — folks who live and die by their body-fat percentages — in which Loren Cordain, an exercise physiologist at Colorado State University, found that results from three different body-fat testing methods commonly used at health clubs varied so widely as to be useless. When pinched by calipers, the pump-you-uppers' body fat averaged 10.4 percent; when dunked in an underwater weighing tank, it rose to 12.5 percent; and when zapped by electricity (fat offers more resistance to electrical currents than muscle, bone, or fluid), it shot up to 16.7 percent. Even retesting using the same technique yields troubling inconsistencies: In a University of Arizona study, researchers deployed four different brands of calipers on the same subject and came up with four different measurements. "Short of carcass analysis," says Cordain, "there are no absolute ways to test body-fat composition."
Besides, there's new proof that body-fat percentage is hardly the be-all and end-all of fitness. A soon-to-be-released study performed at the acclaimed Cooper Institute for Aerobics Research, which monitored 22,000 men, showed that clinically overweight yet clinically fit men had one-third the risk of dying early from cardiovascular disease as men considered to be of normal weight but who fared poorer on a treadmill test. Food for thought, as it were.