brynndragon | Is the "Obesity Epidemic" a fantasy?

One of the things I noticed when examining the requirements for the study I'll be participating in is the BMI cutoff is 27. Which seems strange because the BMI cutoff for "overweight" is 25. Apparently it *was* 27 until 1998 when the National Heart, Lung, and Blood Institute (NHLBI) decided to make it 25. I can't for the life of me figure out why they made that decision. They state, "The rationale behind these definitions is based on epidemiological data that show increases in mortality with BMIs above 25 kg/m2." with several references. But only one of the references implies that lowering the cutoff might be beneficial (the one that states "available evidence suggests that minimum mortality occurs at relative weights at least 10% below the US average", where the average according to this article (referenced in other places in that NHLBI document) is right around BMI = 25 for women and somewhat above that for men - which makes me wonder why the hell they picked 25). All the rest use overweight = 27 as their basis for making statements about the link between overweight/obesity and morbidity, except the WHO report (PDF). The WHO report doesn't say a damn thing about links between obesity and morbidity/mortality (being focused on malnutrition), nor does it give any specific recommendations at all about where to set BMI even for determination of malnutrition (for which it has good reasons involving the risk of overlooking important aspects of the link between height/weight/age and morbidity/mortality, and translating it into useful intervention, which the NHBLI seems to have completely ignored).

The thing I really want to point out is almost all of the data they use to support the notion that being overweight leads to increased morbidity/mortality involves a BMI >27, not a BMI >25. This might explain why the study I'm participating in uses the 27 cutoff rather than the 25 cutoff.

I probably only care because my BMI is 26. Well, that and the idea that over half of Americans are overweight is based almost entire on this change for which I've found pretty much no freaking evidence. The more I learn, the more dubious I am of our notions of healthy weight. . .