My Awful Secret

By Terry Dunkle, Diet Power Founder and Editor-in-Chief

Not long ago, after evading the question for years, I began wondering exactly how much body fat I was carrying. I knew I was 30 pounds overweight, but since I walk or jog three and a half miles daily (I haven't missed a single day this year), I reasoned that a lot of the overweight was tied up in leg muscle and didn't really count.

Still, I really wanted to know my fat content, because I had read that it was a more important measure of health than mere body weight. Excess fat raises your risk of cancer, heart disease, stroke, and diabetes. It also means you're weaker, physically, than you ought to be.

A person's healthy body-fat range depends on age and sex. My healthy range is 11 to 22 percent. I learned that from this chart by the Tanita Corporation, based on guidelines from the National Institutes of Health and the World Health Organization:

Once you know your body-fat percentage, you can easily calculate how many pounds of fat you're carrying. If you weigh 150 pounds and your body-fat reading is 27 percent, for example, your body contains 150 x 0.27 = 40.5 pounds of fat. The remaining 109.5 pounds are muscle, bone, other tissues, and the Double Whopper with Cheese that you just ate.

Many people who look thin actually have a high percentage of body fat. Meanwhile, some of those who appear chunky have low fat levels. (That's what I was counting on.) A woman could double for Kate Moss and still be a heart attack waiting to happen. Or she could look like Rosie O'Donnell and be the fittest person on her block.

In my case, the double was Drew Carey, but I wanted it to be Jerry Seinfeld. I resolved to lose those 30 pounds.

I knew that losing weight wouldn't necessarily lower my body-fat percentage, however. The loss might be mostly muscle, which would actually raise my fat percentage. That's why experts advise getting plenty of exercise when you're losing weight.

How to Measure?

Until recently, finding your body-fat percentage required weighing yourself under water and comparing the results with your terrestrial weight, then plugging these into an equation. The underwater method worked because fat floats and bone doesn't. You had to go to a laboratory or a gym to perform the test, however, and it was expensive. As an alternative, you could measure a pinch of skin at several points on your body with a pair of calipers and plug those numbers into an equation. The caliper method was far less accurate, however.

To make matters worse, neither test is reliable if performed only once:

• Your fat percentage fluctuates as you gain or lose water. A woman's reading may rollercoaster by several points during her monthly cycle—and everybody's will change during the course of a day.
• Fat calipers are prone to user error. What one person calls "an inch of pinch" may look like an inch and a quarter to another.
• Underwater weighing, although still considered the gold standard, isn't perfect. The results vary with the amount of air remaining in your lungs while you're submerged.

The Tanita Breakthrough

In 1994 the Tanita Corporation, a 50-year-old company based in Tokyo, solved these problems by introducing the world's first household body-fat scale. Today's version is even more impressive. Step onto its metal foot pads and you'll see your body-fat content appear in its LCD readout in just a few seconds. In most cases, the reading is very close to what you'd get if you weighed yourself under water.

A Tanita scale works by bioelectrical impedance analysis. The foot pads send a weak and harmless* electrical current through your body, and a computer chip inside the scale measures how long the signal takes to complete the trip. Because electricity travels more readily though muscle and bone, the chip can deduce how much of your body is fat. All it needs to know is the travel distance—your height, which you enter the first time you use the scale.

* The manufacturer says you shouldn't use this scale, however, if you wear a pacemaker or any other implanted electrical device.

The Truth Comes Out

To answer my nagging question, I bought a Tanita BF-662—one of many models you can find on the Web or in department stores. The 662 is billed as a Family and Athlete model, because it stores settings for up to four people and is accurate even if you're "athletic."

That wasn't why I chose it, however. To Tanita, "athletic" means getting at least 10 hours of exercise per week, and I'm getting only half that amount. What I liked was the 662's precision: it measures your body fat to the nearest 0.1 percent. (Another thing I liked was that buying the 662 helped me get rid of more money.)

The Tanita BF-662 is one of many body-fat scales you can buy online or in department stores. Click to visit Tanita.

My moment of truth arrived a week ago, when the Fedex man (six-five, 220, body fat 9 percent; I hate him) dropped a neat white package on my porch

Reverently I opened the box. Mirabile dictu! Right there on top were the four AA batteries that the 662 requires. (Companies that sell products with Batteries Not Included deserve a special place in hell. Maybe an unusually hot room where they are given battery-operated fans, without batteries.) And when I slid the scale out of its case, I discovered that the battery cover is permanently attached. (I have a houseful of heirloom-quality gadgets that are worthless because their battery covers are missing.) This is a company whose engineers actually think about the customer.

The instructions were an added delight. Usually, they're printed only in English and say things like, "Introduce peg A to hole C with falcate wrench, turn right. Very bad turning left." Tanita's instructions are in three languages, and they're so thoughtfully written that I could understand even the French.

After entering my age, sex, and height with the color-coded set buttons, I mounted the 662's platform, placing the balls of my feet on the front pads and my heels on the rear pads. Almost instantly, my weight appeared on an LCD panel large enough for most people to read without their glasses. I didn't feel any electricity. (No surprise there. The signal—500 microamps at 50,000 cycles per second, for you electrical engineers—is too weak to tickle a fly.) But in a few seconds the display changed, and there, emblazoned in gray between my pink, bony feet, was my Actual Body-Fat Percentage.

I've Got Work to Do

Okay, it was 28.0 -- six points north of the "healthy" range for my age. And after checking it daily for a week (as Tanita recommends), I found that it averaged 27.2. For my sex and age, that's right on the edge of "obese."

So I can't lie to myself anymore. I'm lugging 60-some pounds of fat around my three-and-a-half-mile running route every day, and I should be carrying only 15 to 37.

Thanks to Tanita, my objectives are now clear:

• Lose 30 pounds.
• Make most of that loss fat, not muscle.

I also know how to accomplish these goals:

• Use Diet Power.
• Build muscle in my upper body, too.

See you at the gym!