Class 1 Obesity: Don’t Worry, Be Happy?Thursday, January 3, 2013
According to a landmark paper in this week’s issue of JAMA, I now realize that I need to gain about 75 lbs to get the most out of my pension plan.
Indeed, that is just about how many extra pounds I would need to pack on to achieve a BMI of 33, which would finally put me squarely in the Class 1 obesity range. That, according to this extensive review of the literature, would bestow me with the longest life expectancy.
Unfortunately, this will not be easy – If I recall correctly, Morgan Spurlock (the fellow in Super Size Me) only managed to gain a measly 25 lbs – and I recall how hard he had to work at this.
Or, could it perhaps be that the results of this paper are so obviously nonsensical, because the researchers asked the wrong question?
After all, who still cares about BMI?
I can only assume that my US colleagues were far too busy running their analyses to have time to read the Canadian Medical Association Journal (CMAJ or Canada’s version of JAMA), which happened to publish our analysis of data from the US(!) National Health and Nutritional Education Survey (NHANES) on this issue.
As readers of these pages may recall, our analysis of applying the Edmonton Obesity Staging System (EOSS) to two independent NHANES datasets, essentially showed that when it comes to mortality, what matters is how “sick” your are and not how “big” you are.
If you have a weight-related health problem (i.e. EOSS 1+), you die, if not, you don’t – end of story!
Neither BMI nor waist circumference were much use in predicting mortality – but whether or not you had hypertension, diabetes, or sleep apnea was.
As we outline in our paper, not only would BMI overestimate health problems in millions of US citizens, it would also completely miss about 25 million Americans, who do have weight-related health issues, despite falling well below the BMI 30 obesity range.
Perhaps, after this paper, we can finally lay BMI to rest and stop trying to predict people’s health with just scales and measuring tapes.
Hopefully, the only landmark that this paper leaves behind is a tombstone – BMI – RIP!
Let us now get back to actually taking a good medical history, doing a thorough physical exam, and running some tests before declaring someone too light or too heavy for their health.
And in the meantime, let’s not forget that prevention best starts by not losing sleep over your weight unless you have to.