Editorial by Little and Byrne

It is generally accepted that obesity is a health hazard because of its association with numerous metabolic complications such as dyslipidaemia, type 2 diabetes, and cardiovascular diseases.1 On that basis, health agencies 2 3 have proposed that obesity should be defined on the basis of weight in kg expressed over height in m2, the so called body mass index,4 initially described by Quetelet in 1869 (table). Epidemiological studies have reported a progressive increase in the incidence of chronic diseases such as hypertension, diabetes, and coronary heart disease with increasing body mass index.1-3 However, despite this well documented evidence, physicians are, in their daily practice, perplexed by the remarkable heterogeneity found in their obese patients. For instance, some patients show a relatively “normal” profile of metabolic risk factors despite the presence of substantial excess body fat, whereas others who are only moderately overweight can nevertheless be characterised by a whole cluster of metabolic complications, increasing the risk of type 2 diabetes, coronary atherosclerosis, and cardiovascular disease.

In this regard, epidemiological and metabolic studies …