Cutting off the threshold heads, screw logic

Comments about their body mass index cut offs of BMI

This article reported on the Danish population, and suggested suitable body mass index cut-offs thresholds to define Overweight and Obesity. (Actually, the article labelled these as “Moderate overweight” and “Extreme overweight”). Anyway, here are the thresholds suggested.

	Overweight	Sensitivity	Specificity
Men	26.1	77.5%	84.7%
	27.2	62.4%	93.5%
Women	25.0	90.0%	92.4%
	26.9	63.2%	98.8%

	Obese BMI
Men	31.9	92.9%	98.7%
	31.8	93.5%	98.6%
Women	33.1	97.6%	99.7%
	31.4	99.6%	98.7%

The article gives two choices for each threshold, and shows the sensitivity and specificity that would result. I should point out that the numbers for sensitivity and specificity are high, much higher than typically seen in other studies, which suggests that there is a problem with this study somehow.

But at least, this article is an example of an opinion about BMI thresholds, that differs from the usual international standard values of 25 and 30.

The mean age in this study was 41.5 yrs for men, and 42.7 yrs for women. The study didn’t measure body fat percentages. Instead, it analyzed distributions of Body Mass Index in the population, and adjusted the thresholds, to treat men and women equally on a statistical basis. So even if you don’t agree with the exact numbers for the thresholds of body mass index cut offs, this article gives some guidance to the suitable gap between mens and women’s values ( when sensitivity and specificity are reasonably equivalent).

So, they just analyzed data, basically doing the same sort of thing I’ve done with NHANES III data, but their dataset was from Denmark.

And the gap between men and women’s numbers, is the result you liked?

Clearly, men and women shouldn’t be called overweight at a singular value of BMI of 25.

Are you not quite yet understanding what I’m saying? It’s OK. The word “gap” is confusing. So ignore it. Think of it like this. Men should have 27 and women should have 25, hypothetically, as the limit that defines BMI for overweightness. And that doesn’t apply to everyone of all ages. It would only apply to young adults. So I could also say that at age 50, a Male could have BMI of 30 and a Female could use BMI of 28 as cutoff that defines overweight. See what I mean? Men and women having different values, the numbers separated by about 2 from each other.