There is a substantial body of literature which demonstrates that body mass index is a useful marker of obesity. Most of you probably realise that with obesity comes an increased incidence of certain comorbid conditions (ie high blood pressure, high cholesterol, and diabetes). The tendency for obesity and these comorbid conditions to cluster together lead to the defining of a clinical syndrome known as "the metabolic syndrome" and this syndrome carries with it a significant increase in many problems, including cardiovascular problems (eg heart attacks). It is more likely that abdominal obesity (which is correlated with visceral adipose tissue) is a better predictor of metabolic risk factors and since waist circumference is a good proxy measure of abdominal obesity, part of the definitiion of the metabolic syndrome is a waist circumference greater than 40in in men and 35in in women. Clinically, we tend to treat obesity based upon measures of body mass index (it takes very little skill to distinguish an overweight from an athletic body habitus) and we use waist cicumference to help define the presence of metabolic syndrome. So, body mass index is useful if interpreted and applied correctly, but as far as its utility in the Style forum......well, I suspect that Dr. Bresch is conducting a very surreptitious study of our habits.