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    The Body Mass Index

    To understand the issue of weight and wellness, you first need to know your BMI, the common measure of fatness that is at the heart of the debate.

    To find your BMI, use a BMI calculator. A BMI of:

    • 18.5 or less is considered underweight
    • 18.5-24.9 is considered ideal weight
    • 25-29.9 is considered overweight
    • 30 or higher is considered obese

    Many doctors and researchers say the BMI is a useful tool to determine whether someone is overweight or obese, though they concede it has limitations. But critics say the BMI is an inaccurate gauge of wellness.

    "This overweight category of body mass index of 25 to 29.9 is a phony category. It doesn't have medical justification," says Paul Campos, JD, a law professor and author of The Diet Myth: Why America's Obsession with Weight Is Hazardous to Your Health.

    Campos says the BMI was developed as a statistical sorting tool for researchers and was never meant as a gauge for weight loss.

    "It just doesn't make sense," he says, pointing to muscular celebrities such as Matthew McConaughey and Brad Pitt, who he says would be considered too heavy based on their BMI numbers.

    The well-muscled and the big-boned have often found themselves in the BMI's overweight or obese categories, a frequent criticism of the body fat measurement. Indeed, one recent study found that more than half of National Football League (NFL) players were obese according to their BMIs.

    Patrick M. O'Neil, PhD, director of the Weight Management Center at the Medical University of South Carolina, agrees that BMI numbers alone should not be used to determine whether someone needs to lose weight. It's important to believe one's eyes, he says.

    However, O'Neil believes the BMI is generally a good clinical tool for initial screening.

    "The BMI is an excellent tool for helping you figure out where you are," he says. "It's a lot less useful for helping you figure out where you personally need to be."

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