The Skinny on Fat Monitors
Small? Yes. Nifty? Yes. Accurate? Not always.
by Courtesy Oregon Scientific
Discussing the percentage of your body that’s composed of fat seems unsavory, but here I am, baring it all, with an Oregon Scientific Personal
Fitness analyzer (PFA112; $100;
www.oregonscientific.com) clenched between my fingers. The device sends an electrical impulse through my body, measures the resistance from my flesh and bones (fat impedes more than muscle), and flashes the verdict: 17 percent. Excuse me? Twenty percent is normal and considered healthy, but when I was tested recently my fat content was less than 10
percent (not surprising, given my diet and eight hours of cycling a week). My occasional headlong dive into
a plate of nachos notwithstanding, the PFA was plain wrong. Body fat analyzers that measure electrical impedance can vary by 3 percentage points on the best days, more if your hydration level is low or temperature is high. But a distortion of 70 percent? If you really want to measure your body fat–without using the accurate but expensive methods found in clinics or hospitals–I suggest you use the PFA for motivation or
measuring progress, not for the gospel truth. As for me, when I want to hear insults about my body, I’ll take my shirt off in front of my riding buddies–it’s $100 cheaper.