The federal government defines "overweight" and "obese" using the body mass index (BMI), a simple calculation based only on height and weight. "Normal" weight is defined as a BMI between 18.5 and 24.9. "Overweight" is defined as a BMI between 25 and 29.9. "Obese" is a BMI of 30 or higher.
Are these classifications meaningful? According to the government standard, Tom Cruise, Sylvester Stallone, and Mel Gibson are technically obese. So are sluggers Sammy Sosa and Barry Bonds, boxer Mike Tyson, quarterback Donovan McNabb, and wrestling superstar The Rock. And if politics is your thing, it turns out that California Governor Arnold Schwarzenegger—a bodybuilding legend—is obese, too.
It’s not just the official category of obesity that has been affected by numerical hocus-pocus. Thirty-five million Americans went to sleep one night in 1998 at a government-approved weight and woke up "overweight" the next morning, thanks to a change in the government’s definition. That group includes currently "overweight" celebrities like Will Smith and Pierce Brosnan, as well as NBA stars Kobe Bryant and LeBron James. It even includes George W. Bush, considered the most fit president in U.S. history. "Overweight" had previously been defined as a BMI of 27.8 for men and 27.3 for women; in 1998 it was lowered to a BMI of 25 for both genders.
The 1998 redefinition prompted a group of researchers to criticize the new threshold in The American Journal of Public Health. They wrote:
"Current interpretations of the revised guidelines stigmatize too many people as overweight, fail to account for sex, race/ethnicity, age, and other differences; and ignore the serious health risks associated with low weight and efforts to maintain an unrealistically lean body mass … This seeming rush to lower the standard for overweight to such a level that 55% of American adults find themselves being declared overweight or obese raises serious concerns."A research letter published in JAMA (the journal of the American Medical Association) reported that 97 percent of players in the National Football League are technically overweight and more than 50 percent are obese. The NFL responded by calling the BMI "bogus," since it "doesn’t consider body muscle versus fat."
"Before calling it an epidemic, people really need to understand what the numbers do and don’t say."
— Rockefeller University professor Jeffrey Friedman in The New York Times, 2004