America Has an Eating Disorder continued...
According to Census data, the average American woman is about 5'4" tall and weighs a little more than 150 pounds. Her body-mass index or BMI -- a measure of weight adjusted for height -- is 26.3, which puts her in the "overweight" category. Yet she's leaner than half the population.
Campos criticizes those who argue that healthy body mass is between 18 and 21.9 BMI -- "for the average woman 5'4" tall, this is between 108 and 127 pounds," he says. "People flinch if you even say the word fat. It is seen as a poison. We see the elimination of fat as desirable. That is eating-disordered thinking. The difference between fashionable thinness and anorexia is whether you have been hospitalized or not."
People come in all shapes and sizes. Yet we think one size should fit all -- and that size is thin.
"We have turned into a disease the fact that there is a huge variation in normal body mass," Campos says. "There is a huge number of people who are physically active and have nothing wrong with them in terms of anything measurable. They are being 'pathologized' because of this ridiculously narrow definition of what health means."
Blair says Cooper Institute studies show people at much higher BMIs than 25 can be quite fit -- although he stresses that extremely obese people, with a BMI of 45 or more, are almost never fit.
"We find that around half of obese individuals -- those with BMI of 30 or more -- about half do well enough on a maximal exercise test to get out of our 'low-fit category,'" Blair says. "Not only is it possible to be fit and fat, a substantial proportion of fat people are fit. I suspect that 15%-20% of normal-weight people are unfit. I'd like to shift the focus away from BMI."
BMI is an excellent tool for epidemiologists looking at weight across a population. For example, BMI quite accurately shows that the heaviest people are at the highest risk of diabetes.
But on an individual basis, it can yield some absurd results. For example, Campos notes, more than half of the players in the National Football League have a BMI of over 30 -- making them "obese." This includes more than three-fourths of the league's linebackers and tight ends. And nearly all of the league's quarterbacks fall into the "overweight" category.
"It is silly for a doctor to just look at someone's BMI number and recommend weight loss," Blair says. "Suppose you have a person with a BMI of 30 or 31, who doesn't smoke, who eats a diet high in fruit and vegetables, who has good [cholesterol] levels, and who runs a mile every day. Do you tell that person to lose weight? Some fanatics would say yes, you've got to get that BMI down. I think that is silly."