The name Adolphe Quetelet doesn’t exactly ring a bell in most health clubs. But this Belgian scientist created that revolutionary health-assessment tool, the body mass index (BMI), which calculates fatness vs. fitness by dividing one’s weight in kilograms by the square of one’s height in meters. While the formula may seem pretty modern, Quetelet actually developed it sometime between 1830 and 1850. And according to a report published in the July 2010 issue of Mayo Clinic Proceedings, its inability to distinguish between fatty and lean tissue makes it wildly inaccurate. Comparing the BMI of 140 heart-failure patients with a more thorough process called a DEXA (dual energy X-ray absorptiometry) scan, they found that BMI misclassified the body-fat levels of 41 percent of patients. Because fat takes up four times more space than muscle tissue, it’s possible to weigh less than a similarly built person yet be more fat. For example, a heavily muscled athlete like the Baltimore Ravens’ 5-foot-eight-inch, 212-pound running back, Ray Rice, would have a much higher BMI than a couch potato. As an alternative, the calipers measurement you can get at most gyms provides a more accurate evaluation. But there’s an easier way: Simply tape-measure the widest part of your abdomen and then your hips and calculate your waist to hip ratio. Generally speaking, men should aim for a ratio below 0.9 and women below 0.83. Thanks for nothing, Adolphe Quetelet.