Computing and Expressing Degree of Fatness

To the Editor.— Direct measurements of degree of fatness are seldom practicable. Among the most commonly recommended methods for expressing fatness are (1) use of standard tables of weight and height and (2) computation of the body mass index (BMI): weight, in kilograms, is divided by the height, squared, in meters (wt/ht2). Among the advantages of the latter is that in most circumstances, the index is independent of height. In a population of 973,I found this to be the case in both men and women. A disadvantage of the BMI is that the significance of a given result differs substantially by sex. For example, a man with a BMI of 21.4 is a bit underweight; a woman with a BMI of 21.4 is a little overweight. Thus, data from men and women cannot be analyzed together. A common difficulty with using the standard weight-for-height tables is that standardization has