There is a Marx Brothers film in which the brothers are searching for hidden treasure in a house. When no treasure is found after an exhaustive search, one brother suggests that they may have the wrong house – that perhaps the treasure is hidden in the house next door. On looking outside, the brothers find to their dismay that there is no house next door. They immediately begin drawing up plans to build one.
A similarly crazed logic appears to have replaced rational scientific enquiry among epidemiologists. In a letter to the New England Journal of Medicine, three supposedly sane researchers report that although there is no major obesity problem in Hong Kong, there is a high prevalence of disorders normally 'linked' with obesity, such as type 2 diabetes, hypertension and dyslipidemia, often occurring among patients who are well within the 'normal' BMI (body mass index) range.
Rather than investigating whether factors other than obesity might be responsible for the conditions in question, or even considering this as a possibility, the researchers propose that the criteria for obesity be lowered for Chinese persons, so that the normal-weight patients exhibiting these symptoms can be classified as overweight or obese. Lowering the BMI 'cutoff' used to determine overweight/obesity would, at a stroke, create an 'obesity epidemic' in Hong Kong, which could then provide a convenient explanation for the high incidence of diabetes, hypertension, etc. In terms of identifying other possible causes of these conditions, it would of course be about as helpful as the Marx Brothers' new house. But then exhorting patients to lose weight is much easier than doing proper scientific research. And questioning one's pet theories when faced with contradictory evidence is very hard indeed.