BMI-Me Up?

Insurance companies, schools and the medical industry place an increasing emphasis on the body mass index as a beacon for overall health – but does it speak the truth about you?

By Chad Rubel
CTW Features

The standard of “normal” versus “overweight” no longer seems to be about weight itself, but about an individual’s body mass index. And despite its recent rise to notoriety, the BMI was invented in the early 19th century by Belgian scientist Adolphe Quetelet as a method to simply measure your weight in relation to your height.

However, as its popularity among doctors and health professionals continues to escalate in the 21st century, concerns have emerged about overusing one measurement to determine overall health.

“BMI should be used cautiously when classifying fatness, especially among college-age people,” says Jim Pivarnik, a Michigan State University professor of kinesiology and epidemiology. “It really doesn’t do a good job of saying how fat a person really is.”

A research team from Michigan State University and Saginaw Valley State University measured the BMI of more than 400 college students – some of whom were athletes and some not – and found that in most cases the student’s BMI did not accurately reflect his or her percentage of body fat.

“The overlying issue is the same criteria for BMI are used across the board,” says Joshua Ode, a Ph.D. student in the Michigan State department of kinesiology and an assistant professor of kinesiology at Saginaw Valley. “Whether you’re an athlete or a 75-year-old man, all the same cut points are used.”

According to Ode, BMI has much less relevance if you are physically fit. Those with ample muscle mass would be deemed “overweight” on the BMI scale. Two, 6-foot men, that both weigh 235 pounds, would each have a BMI of 31.9, classifying them obese. However, if one of them lifts weights, his fat content is lower and his muscle mass is higher, making him much healthier than the non-athlete. Similarly, long-distance or endurance athletes would be “underweight” on the chart, even though they would be healthier than someone with the same height/weight measurements.

“A previous study of NFL football players found that a large percentage of them - around 60 percent - were considered obese,” he says. “But when you look at an athlete like that, you see that in many cases he is not obese. Many athletes have huge BMIs because of muscle mass, but in many cases are not fat.”

The National Institutes of Health (NIH) recommends three factors for doctors to use when assessing whether their patients are overweight: BMI, waist circumference (a measurement of abdominal fat), and numerous risk factors such as high blood pressure, cholesterol, high blood sugar and smoking.

To fix the BMI itself, Pivarnik says that instead of having one cutoff point for everyone, it is a better idea to have different classifications for different people.

“Is a BMI of 25 for overweight and 30 for obese the right ones to use with 20- to 29-year-olds in terms of disease risk?” he asks. “Maybe it could be as simple as this: If you’re a regular exerciser or an athlete, maybe 28 is overweight for you and 33 is considered obese.”

BMI, says Pivarnik, is used as a “surrogate” for percent fat, even though body fat doesn’t really fit into the equation.

“What if you take fat out of the equation?” he says. “Is there something unique about BMI that may increase a person’s risk of chronic disease, unrelated to fatness? Are people with high BMIs but low fatness as much at risk of heart disease as other people? The answer is no one knows.”

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