Body Fat. Contract your abs and grab your belly. Anything in your hands doesn't need to be...

Hi guys. Here's an article about those handy at-home body fat scales. I have tried to paste the article in here. To be safe, here also is the url: http://www.washingtonpost.com/wp-dyn/content/article/2008/05/02/AR2008050203388.html?hpid=smartliving The article and an online chat are on the Washington Post website. Grab a handful and read on. Should You Trust That Body Fat Test? By Howard Schneider Tuesday, May 6, 2008; HE03 Depending on which Japanese conglomerate you believe, either I have the body of a 25-year-old or I'm pushing 70. Which is disconcerting either way, because I was a mess when I was 25, and I'd prefer to let 70 wait its turn. But according to the statisticians at such companies as Omron and Tanita, my "metabolic age" lies at one of those extremes. What's "metabolic age"? It is a statistical construct that, along with a growing number of other bells and whistles, is being built into the "body composition" monitors proliferating on store shelves. There are a good half-dozen or so of these machines on the market now, at places including Target, with prices from about 30 bucks to nearly 300. Typically similar in shape and use to bathroom scales, their main purpose is to measure body fat. They use a technology called bioelectrical impedance, which passes a small current through conductive foot pads or handheld electrodes (and, in some cases, both). The current can pass easily through water-rich muscle fiber, but it bogs down in fat. Based on a measure of impedance (how much of the current gets through from one electrode to the other), the machines use mathematical models to estimate the amount of fat that got in the way en route. Why is this a good idea? It is pretty widely acknowledged that people should be less concerned with what they weigh than on whether that weight comes from fat or muscle. The Mayo Clinic uses the (frightening) term "normal-weight obesity" to capture the issue. The scales may treat you kindly, in other words, but if too much of your weight comes from fat, as opposed to lean tissue, you run some of the same health risks as those who are obese. For men, the aim is to keep body fat under about 20 percent of total weight; for women, under about a third, though the numbers vary with age. Not content with that statistic, however, competing companies have begun loading their machines with lots of other stuff: estimates of how much muscle you have, how many pounds of bone, hydration levels, the amount of "visceral fat" larded around your vital organs, how many calories you need to eat in a day, and, based on all of the above, how "old" you are. Which prompts the question: If the age estimate given by two monitors can be so divergent, what about the rest of the stuff the machines are supposed to measure? To get a sense of the accuracy of retail-grade monitors, at least when it comes to that basic measure of body fat, I gathered five models from three companies and matched them against two clinical methods for taking the same measurement: a hydrostatic "dunk tank" test often used in research and the hand-calipers pinch test often performed in health clinics and gyms. The two clinical measures, taken by doctoral student Andy Ludlow at the University of Maryland, raised a point that representatives for the monitor companies like to emphasize: that even accepted standards such as the dunk tank, which uses formulas related to the displacement of water and the comparative density of muscle and fat, are still only estimates of body fat. In the case of the monitors, the mathematical models involved have many built-in assumptions -- particularly when it comes to things such as visceral fat -- and if your body strays from that norm, results will be less accurate. "The only true way to measure body fat is through an autopsy," said Herb Conroy, group marketing manager for Homedics, one of several companies that sell body fat monitors. (Thanks, but I'll pass for now.) The dunk tank put me at just under 21 percent, a bit higher than it should be, while the pinch test registered 18 percent, comfortably within the recommended range. So should I panic, or have a beer? That's the kind of anxiety this test can prompt. Company representatives seem to understand as much and are generally careful to say that their machines should be used more to establish trends than for precise measurements. The devices, in other words, will give you a rough sense of where you stand but are better used to see whether your body fat percentage is going up, down or staying steady over time. If you're losing weight, for example, and you're body fat is creeping higher, that's a sign of unhealthy dieting -- weight loss through dehydration or the destruction of muscle tissue. By contrast, if you're body fat readings are going down but the scales are not budging, that's a sign that you're building muscle and getting stronger. "What we try to tell everybody is: Don't get hung up on 'Am I really 20 percent?' " said Keith Erickson, director of North and South American sales for Tanita. "It's a tool. It's not an absolute." From that perspective, the monitors -- two from Omron, two from Tanita and one from Homedics -- came reasonably close to Ludlow's estimates. They ranged from a low of 18 percent (Tanita's higher-end Ironman Innerscan model, which also gave me credit for a heck of a lot of muscle, and a 25-year-old's metabolism), to a high of 20.9 percent (Tanita's less expensive model UM061). The two Omron models came up with similar numbers: 20.7 percent from the more-expensive Full Body Sensor (which, alas, also put me near the end of my life expectancy, based on estimates of muscle content and metabolism) and 20.1 percent from the company's hand-held HBF306 Body Logic, a model popular among personal trainers and health clubs because of its low cost and small size. The Homedics 540 Health Station was the outlier, putting me at a whopping 29 percent fat. Switched to "athlete mode," a feature on many monitors that uses different assumptions about muscle tissue, it registered a lean 12 percent. Anyone considering a purchase should keep an important point in mind: They are twitchy, especially when it comes to hydration levels. In doing this test, I was careful to use all of the monitors just before I got into the dunk tank, so the condition of my body would be the same. Had I tested them an hour before, or an hour later, had a glass of water, eaten a meal or gone for a workout, the readings likely would have changed. The manuals for the different retail monitors come with plenty of advice to address this: Don't measure after eating; don't measure after exercise; don't measure after drinking alcohol; don't measure in the morning because you're dehydrated; don't measure after showering because you've just been soaked with water. The recommendation: Take any measurements around the same time of day, say just before supper, and don't pay too much attention to daily fluctuations. "With any monitor, consistency of use is what's important," said Kristin Vitek, a product manager for Omron Healthcare. Given all the caveats, I wonder how much value the machines really add. If you're attracted to technology and like to quantify things, this is a reasonable purchase, used correctly. But here's an alternative: Contract your abs and grab your belly. Anything in your hands doesn't need to be there.

Doug. I think you forgot the link.  I am intrigued though.

Scott, Oops! I thought I had pasted the article in there, but then it disappeared. So I've tried again, along with the url. Hope this works.