Here's the formula for calculating it. Determine your height in inches and then multiply that figure by itself. Then, take your weight in pounds and divide it by the square of your height in inches. The result should be a low figure, such as .03543279. The last step is to take that number and multiply it by 703.

The answer should be a two-digit number. A number less than 25 is considered to mean that the person is not overweight. A person with a BMI of between 25 and 29 is considered overweight. And a person with a BMI of 30 or more is considered obese.

Before you panic, we would like to explain that the formula is imperfect, because it does not consider the difference between fat and muscle. "Mass" does not distinguish between them. Illustrating the shortcomings of the formula, Sammy Sosa and Arnold Schwarzenegger are obese by that standard! And Brad Pitt and Michael Jordan are overweight.

Nonetheless, the formula can give one a general guideline of a healthy weight range.

—Sources: George F. Will, "Supersize Menace," The Washington Post, Feb. 28, 2002; Kathleen Parker, "In War on Fat, It's the Food's Fault," Jewish World Review, July 31, 2002.