Читать книгу Nutrition For Dummies - Carol Ann Rinzler - Страница 57

The body mass index (BMI) is a number that measures the relationship between your weight and your height. Currently in the United States, a BMI below 18.5 is considered underweight, 18.5 to 24.9 is normal, 25.0 to 29.9 is overweight, 30.0 to 39.9 is obese, and 40.00 or greater is severely obese. Previously, other countries were slightly more lenient in their estimate of normal and overweight; for example, in Australia, a BMI of less than 20 was considered underweight. Today, the American standards are generally accepted around the world.

The equation used to calculate your BMI is called the Quetelet Index, named after the 19th-century Belgian mathematician and astronomer who invented the concept of “the average man” (see the nearby sidebar “The man who invented the average man”). The equation is W/H², which originally meant weight (in kilograms) divided by height (in meters, squared). The American equation, however, divides your weight in pounds by your height in inches, squared. So if you are five foot three inches tall and weigh 138 pounds, the U.S. equation looks like this:

 BMI = W/H2 x 705= (138 pounds/63 x 63 inches) x 705= (138/3,969) x 705= 24.5 BMI