Body Mass Confusion

Everyone knows a majority of Americans are overweight.

Our drive-through "gimme a No. 2, and make it snappy, I got to get home to watch 'Gossip Girl'" lifestyles have caused our waistlines to balloon.

Nowhere is this epidemic of fatness more apparent than in professional sports, where more than 90 percent of the players in the NFL and 50 percent on NBA rosters are overweight.
Take Emeka Okafor. The former UConn super-genius and basketball star may play the most demanding aerobic sport this side of boxing, but at 6-foot-10 and 252 pounds, he is way, weigh overweight, under the guidelines the government uses to determine such things. Among the other overweight folks whom state sports fans might remember are Josh Boone, Ben Gordon and Caron Butler.

These unusual overweight examples spring from the stubborn math of the Body Mass Index. The BMI is a measure of body fat based on the ratio of your height and weight. A BMI of 18-25 is considered normal, between 25-30 overweight and over 30 obese.

The method, invented by a Belgian man named Adolph Quetelet in the 19th century, started to gain acceptance in the 1950s and has been used by the World Health Organization since 1980 to track health trends throughout the world.

When you read a newspaper story that says a majority of Americans are overweight, it is based on the BMI. When your doctor doesn't take out the calipers to measure your body fat but suggests you lose a few pounds, this is based on the BMI.

The question is whether a metric that can be wonky in individual cases, such as Okafor, is a reliable measure of whether we are overweight. The Department of Health and Human Services admits that the BMI has shortcomings because it "may overestimate body fat in athletes and others who have a muscular build" and "may underestimate body fat in older persons and others who have lost muscle mass."

Defenders of the BMI say the distortions that can take place in individual cases are not meaningful when sorting through large amounts of data because few of us have the muscle mass of professional athletes.

"The best measure on an individual basis would be to use the percentage of body fat," says Kelly Brownell, director of the Yale Center for Eating and Weight Disorders. "But the BMI is the best statistical measure easily obtained for a large population."

Brownell says that whatever metric is used, one will quickly discover that "obesity is a staggering problem in this country and, increasingly, in the rest of the world."

There is no doubt that Americans are adding weight.

Data from the Centers for Disease Control and Prevention shows the average American male in 1960 was 5 feet, 8 inches, 168 pounds. By 2002, he had grown up and out to 5 feet, 9 ½ inches and 191 pounds. Women added 1 inch and 24 pounds during the same period.

But guess what? While nearly every story written about obesity says that 1980 was the moment when America began getting fatter, the average American male in 1960 was overweight according to the BMI. He just didn't know it.

The same could be said for about 35 million Americans who suddenly found themselves classified as overweight when the BMI guidelines were adjusted, moving those with BMIs between 25 and 27.4 (for women) and 27.8 (for men) out of the "normal" category.

What is at stake?

For Brownell and others who agree with him, obesity is a staggering public health crisis that needs to be dealt with on an individual and societal level. They point to data that shows diabetes mortality has risen from 16.4 in 100,000 in 1980 to more than 20 in 100,000 in 2004. They point to other data that suggests an increase in the risk of heart disease and some cancers among the overweight.

Pushing back are people such as Sandy Szwarc, a registered nurse and food writer, whose blog Junkfood Science attacks the mainstream view that obesity is a looming health crisis. Critics of Szwarc, and others such as Paul Campos and Jon Robison, an adjunct professor at Michigan State, point to ties to the food industry and the restaurant lobby. But they also have data supporting some of their claims that BMI standards have no medical validity and are arbitrarily assigned.

They were quick to pounce on the methodology of a highly publicized CDC report in 2004 that blamed more than 400,000 deaths each year on obesity, which meant that weight rivaled smoking as a killer.

This number is still repeated in stories about the issue (including an Los Angeles Times story from last November) despite the fact that the CDC recanted the very next year, issuing a report that placed weight-related deaths at fewer than 30,000 each year.

More recently, the CDC issued a report suggesting those with BMIs between 25-30, that is to say overweight people, had lower mortality rates than people in the normal weight category. People who were classified as overweight had lower risk of a variety of diseases including Parkinson's and lung disease that counteracted their increased risk of heart disease, diabetes and some cancers.

While being healthy and not dying aren't the same thing, the report was still sweet soul music to those who have argued that the categories of the BMI are arbitrary and that, as J. Eric Oliver argued in "Fat Politics: The Real Story Behind America's Obesity Epidemic," fat and fit are not exclusive terms.

Despite the bitter battle lines between the two groups, they agree on one thing: If you are out there, feeling remorse for the egg nog binge you went on in December, do not go to the Internet, find a BMI calculator and begin a crash diet that will, both sides agree, lead to an inexorable binge and eventual weight gain.


Source:www.courant.com