When Body Mass Index, or BMI, gets face time in the Fashion & Style section of the Times, as it did today, you know something’s up. Along with blood glucose, waist circumference, blood pressure, and others, BMI is a measurement that helps identify cardiometabolic risk. If one of these measurements is abnormal, there is an increased chance that another is too. Therefore, BMI is a very important measurement for the many Americans who have or are at risk for type 2 diabetes. But, for schoolchildren, adoptive parents, models???
We can only think that those for whom a low BMI is really important are so numerous now that everyone wants one! Indeed, once only a measurement important for health agencies, BMI is now appearing all over the place. This article discusses the September ban on runway models in Madrid whose BMI was below 18.5, China’s recent mandate that prospective adoptive parents for Chinese children have, among other things, a BMI under 40, and the report cards in Arkansas and Tennessee that include childrens’ BMIs. One calculates a BMI by dividing a person’s weight in kilograms by his or her height in meters squared (try it yourself – with pounds and feet – at www.nhlbisupport.com/bmi/).
The truth is, the article points out, BMI alone is not really a good gauge for general metabolic health: “The number should not be the final word for measuring whether a person is under- or overweight to an unhealthy degree, some experts say.” BMI is really only one of several measurements that matter. It does not distinguish between fat and muscle mass, the article points out, so that Arnold Schwarzenegger as Mr. Universe was technically obese (with a BMI of 33). Some studies show that sedentary people with lower BMIs are actually at greater risk for diabetes and heart attacks than fit people with higher BMIs. Part of why BMI remains an accepted gauge of health is because it’s easy to calculate and cheap, Ellin writes. Read the article below:
Fashion & Style: Quick, Do You Know Your B.M.I.?
By ABBY ELLIN
Published: December 28, 2006
IN the past, you could learn a lot about a person from a group of letters: Ph.D., D.D.S., V.F.W., D.W.I. Now another set looms ahead, and it affects everyone from teeny tiny models to adoptive parents to schoolchildren: B.M.I. or Body Mass Index.
But few people actually know what it means.
“I know that having a low B.M.I. is supposed to be a good thing, but I have no idea what it really is or how to figure it out,” said Hilary Black, 35, the editor of Tango, a magazine about relationships. “Keeping track of my weight is more important to me than keeping track of my B.M.I.”
Ms. Black is not interested in adopting a child from China. If she were, she might be very concerned with her index rating. Last week, the government-run China Center of Adoption Affairs mandated that prospective adoptive parents have, among financial, educational, marital and other health requirements, an index rating under 40.
Ms. Black does not have children. If she did, and if she lived in Arkansas or Tennessee, she would receive a report card noting her children’s index figures, in addition to their ability to play nice with others.
Ms. Black might also be worried about her index number if she were a model: In September, organizers in Madrid banned from its runways five models whose index rating was below 18.5. In Milan, fashion industry officials have also barred knife-thin models from its February shows.
The B.M.I. is a mathematical calculation of a person’s weight in kilograms divided by his or her height in meters squared. Since most Americans have no clue what their height is in meters (remember the failed attempt to go metric circa 1976?), it’s easiest to determine an index rating by visiting a Web site like that of the National Heart Lung and Blood Institute (www.nhlbisupport.com/bmi), where one can determine their index rating by entering their height in feet and weight in pounds.
And as the index, a measurement adopted by government health agencies, increasingly gains currency in many areas of life, you may wish to know yours. But how important is it? The number should not be the final word for measuring whether a person is under- or overweight to an unhealthy degree, some experts say.
“Our society is really fixated on numbers, and the problem is when it comes to weight distribution and the risk for heart disease, it’s not just one number — it’s the percentage of body fat, B.M.I. and waist size that matters,” said Dr. Nieca Goldberg, a cardiologist at Lenox Hill Hospital in Manhattan.
Dr. Peter D. Vash, the director of medical affairs at Lindora Medical Clinics, in Costa Mesa, Calif., compares the index to a speed limit. “It’s not always an absolute index in the individual case,” he said.
A Belgian statistician and astronomer, Adolphe Quetelet, invented the index formula in the 1830s. But it wasn’t until the 1980s that public health agencies adopted it as a way of identifying individuals at risk for heart attacks, hypertension, diabetes, stroke and some cancers.
In 1998, two branches of the National Institutes of Health created new guidelines which divided people into categories: You were “normal” if your index rating was between 18.5 and 24.9; “overweight’’ if it was 25 to 29.9; and “obese” if it was 30 or higher.
After the change, many doctors and lay people were up in arms. By the revised standards, nearly 55 percent of the American adult population in 1998, was considered overweight or obese, according to the N.I.H. (Today, 66.3 percent of adults are overweight or obese, according to the Centers for Disease Control and Prevention.)
The index also didn’t distinguish between body fat and muscle mass, so athletes and bodybuilders like Arnold Schwarzenegger, whose rating was 33 when he was Mr. Universe, were technically obese.
That struck some people as odd. Such discrepancies got experts wondering how accurately the index gauges health. Others questioned the reliability of the index because the figure doesn’t take fitness into account.
A low number can be deceptive. Sedentary men with a rating of less than 27 were at a greater risk for heart attacks, strokes, diabetes and certain cancers than fit men with a rating above 30, according to a study of 25,389 men conducted by the Cooper Aerobics Center in Dallas.
“In the past, it used to be felt that if you had a high B.M.I. you had a high mortality and all these risk factors,” said Dr. Michael D. Ozner, a cardiologist and medical director of wellness and prevention at Baptist Health South Florida in Miami. “We now know that exercise is extremely important.”
A study published in the August 19 issue of the medical journal Lancet combined data from 40 studies involving about 250,000 people with heart disease. The researchers found that patients with a low rating in the normal rating had a higher risk of death than others in the normal rating. Overweight patients had better survival rates and fewer heart problems than those with a normal index number.
“We concluded that B.M.I. might not be the best way to assess body fatness,” said Dr. Francisco Lopez-Jimenez, the lead author and a cardiologist at the Mayo Clinic in Rochester, Minn. “The issue is that people with ‘normal’ weight based on B.M.I. may have a lot of fat, and we’re labeling these people as completely healthy when they might not be.”
Yet, the index remains a widely accepted gauge of health, even though some tools are better predictors like say the hip-to-waist ratio in the case of heart attacks. Part of the reason is because it’s simple to calculate and cheap.
It is not the best way to test body fat, but the others are often time-consuming or unreliable. Many gyms use the skin-fold test: a caliper-wielding trainer pinches your body in three to seven places to determine your fat-to-muscle ratio. But the results vary depending on who’s administering the test, and what body parts they pinch.
The method that many doctors consider the gold standard is both tricky and inconvenient, since it requires a patient to be submerged in a water tank, to exhale, and then sit on an underwater scale. (Since fat is less dense than muscle, the more body fat you have, the less you’ll weigh in water.) But most doctors don’t have oversize cisterns in their offices, not everyone can hold their breath for an extended period and “Who wants to get all of their patients naked?” asked Dr. Amanda J. Dupont of the Austin Bariatric Clinic in Texas.
To assess her clients, Charla McMillian, a former Marine who runs FitBoot, a training program in Boston, says body fat is more crucial than the index. “It has nothing to do with how’s their heart, how’s their cardio, how’s their strength,” she said.
Maybe so, but that’s not much of a consolation for Lauri Owen, a lawyer in Bethel, Alaska, who is planning to adopt a 3-year-old boy from China, in March. Ms. Owen, 39, applied in July; her application was accepted a week before the China ruling. “If it had been a week later I wouldn’t have been able to adopt the boy,” said Ms. Owen, who is single and whose index rating hovers between 41 and 42. “It’s appalling. There are so many kids over there who desperately need homes. It was my hope to adopt him and then another child from China. Obviously, that’s not going to happen now.”
Paula Schwartz contributed reporting.