Wednesday, December 4, 2013
Earlier this week, I posted on a study suggesting that “metabolically healthy” obese individuals are at increased risk for diabetes and heart disease – except that the definition of “metabolically healthy” in this study included people with one metabolic risk factor, i.e. people, who would be considered at least EOSS Stage 1 or 2 – not exactly healthy in my books.
Now, a study, by Caroline Kramer and colleagues from the University of Toronto, published in the Annals of Internal Medicine, unfortunately, adds to the confusion.
The researchers conducted a meta-analysis of data from over 60,000 individuals derived from 12 cross-sectional and prospective studies, varying in duration from 3 to 30 years of follow-up.
Their comparison of metabolically “healthy” and “unhealthy” obese individuals lead the authors to declare that, “there is no healthy pattern of increased weight”.
But of course any meta-analysis can only be as good as the original studies included in it.
And herein lies the problem.
As shown in Table 1 of the study, 9 of the 12 studies defined “healthy” as not having the metabolic syndrome (either based on ATP III or IDF criteria), while the remaining studies defined “healthy” as having less than 2 metabolic risk factors.
As readers will perhaps recall, the ATP III defnition of “metabolic syndrome” actually requires the presence of at least 3 of 5 of the components of the metabolic syndrome, while the IDF definition actually requires abdominal obesity AND at least two other risk factors.
Thus, someone with just hypertension or just elevated triglycerides or even just elevated fasting glucose would be considered to be “healthy” in these studies.
This of course is nonsense. The term “healthy” should mean just that – “healthy”.
In the Edmonton Obesity Staging System healthy is defined as the absence of medical, mental or functional risk factors or limitations related to excess weight. According to this rather “stringent” definition, our analysis of NHANES and other data sets, showed virtually no increased risk associated with increased BMI or waist circumference over as long as 200 months.
In contrast, in our analyses, obese individuals with even just one metabolic (or other risk factor) were considered to have EOSS Stage 1 or 2 had clearly elevated risk.
Thus, this meta-analysis simply adds to the confusion on this topic by defining “healthy obesity” that we would consider anything but “healthy”.
Nevertheless, the paper does make two interesting points – neither of which are novel or unexpected:
1) There is considerable metabolic heterogeneity amongst people with elevated BMI.
2) People with elevated BMI (including those at lower risk) are at a higher risk of eventually developing metabolic problems (with increasing age and BMI).
Thus, for clinicians, the message really remains the same:
1) BMI is a lousy measure of metabolic risk in individuals.
2) Even those with elevated BMI who appear at lower risk, should work on maintaining that lower risk (as should everybody else).
Unfortunately, studies such as this, by mislabelling unhealthy obese individuals as supposedly “healthy”, do little than further confuse the literature and promote weight bias while reinforcing the widespread misconception that you can measure health by simply stepping on a scale.
If you are an obese person with Stage 0 obesity and have maintained that “healthy obese” status for years, I’d like to hear about it (yes, these people do exist).
New Delhi, India