Does BMI stand for “Big Malarkey Index?” asks reporter Carolyn Susman in this morning’s Palm Bimeach Post. Picking up on our concerns about the government’s flawed standard separating “normal” from “overweight” and “obese,” she points out that BMI “sounds like code for something kids might giggle about. But it stands for body mass index, and lately it’s become a joke to some people.” There’s no punch line, but there is plenty to be mad about.

Susman also describes how the Center for Consumer Freedom has pointed out that celebrities like Governor Arnold Schwarzenegger, Sylvester Stallone, and Tom Cruise are considered “obese.” She simply asks: “You wanna tell ’em?” But setting that aside, and forgetting for the moment the government’s 1998 decision to shift its definition in such a way that more than 30 million Americans instantly became “overweight” without gaining an ounce, the biggest problem with the BMI is that it neglects a growing body of scientific evidence showing that peoples’ fitness level is far more important than their weight.

How much should most Americans care about their BMI? As the Post reports, “Not much, according to an emerging group of academics.” The article quotes Michigan State University professor Jon Robison:

The BMI is relatively useless as an indicator of health for individuals. Contrary to what we have been told by the government, there is a minimal relationship between increased BMI and health-related issues, except at the very extremes of the weight distribution (very, very fat and very, very thin).

Leading obesity myth debunker Dr. Glenn Gaesser, professor and director of the kinesiology department at the University of Virginia, was also quoted in the Post story. He argues that a “fit man carrying 50 pounds of body fat had a death rate less than one-half that of an unfit man with only 25 pounds of body fat.”

Robison and Gaesser are hardly alone in finding that fitness level is much more important than weight. Authors of a 1999 article in the American Journal of Clinical Nutrition concluded:

In summary, we found that obesity did not appear to increase mortality risk in fit men. For long-term health benefits we should focus on improving fitness by increasing physical activity rather than relying on diet for weight control.

The top researcher in the fitness-versus-fatness debate is the Cooper Institute’s Dr. Steven Blair, whose extensive research has convinced him that peoples’ heft needn’t necessarily weigh them down. Blair wrote for the President’s Council on Physical Fitness and Sports that “active obese individuals actually have lower morbidity and mortality than normal weight individuals who are sedentary.” As Blair says, and the chart below demonstrates, fitness level is more important than weight.

Blair’s most unlikely fan may be Kelly “Big Brother” Brownell, grandfather of the Twinkie tax and a dedicated opponent of all things tasty. Brownell has praised Blair’s work demonstrating physical activity is key to health, saying:

Groundbreaking work on fitness and weight has been done by [epidemiologist Steven] Blair and colleagues at the Cooper Institute. They have shown that the advantages of being fit are striking and that people can be fit even if they are fat … and thus have lowered risk of disease. A remarkable finding is that heavy people who are fit have lower risk than thin people who are unfit.