{"id":521,"date":"2006-08-22T12:52:10","date_gmt":"2006-08-22T12:52:10","guid":{"rendered":"http:\/\/scienceblogs.com\/principles\/2006\/08\/22\/what-do-you-mean-by-normal\/"},"modified":"2006-08-22T12:52:10","modified_gmt":"2006-08-22T12:52:10","slug":"what-do-you-mean-by-normal","status":"publish","type":"post","link":"http:\/\/chadorzel.com\/principles\/2006\/08\/22\/what-do-you-mean-by-normal\/","title":{"rendered":"What Do You Mean by Normal?"},"content":{"rendered":"

Over at Pure Pedantry, Jake has a nice post about a study showing that the ever-popular Body Mass Index measure is not a good predictor of the risk of heart disease<\/a>. He’s got a lot of details about the study, including this graph of risk vs. BMI:<\/p>\n

\"i-61de5c59a97f6c8c0a87b9b9deb6c7d7-bmi.jpg\"<\/p>\n

Now, here’s the thing. This is the second study I recall hearing about that has a similar result– there was a flurry of articles a while back about a large study (or maybe one of those meta-studies) showing that people who were slightly overweight according to BMI had lower mortality than those of “normal” weight. And now, this study shows that people who are overweight according to BMI have a slightly lower risk of heart disease.<\/p>\n

My question is, who’s the idiot who decided what “normal” is? (Mroe after the cut…)<\/p>\n

<\/p>\n

I mean, as a physicist, I would like to think that you would set the “normal” level by basically making the sort of graph shown above, only without the descriptive labels, and then choose the point of lowest risk as your “normal” range, and set “overweight” and “underweight” relative to that.<\/p>\n

Ideally, you would repeat this for several different risk factors– heart disease, diabetes, whatever else you associate with being overweight– making graphs and choosing the local minimum for each as your “normal” point. I mean, that would seem like a sensible definition of “normal” weight, in the sense that this is being used, namely the ideal that healthy people are supposed to be striving for. Ideally, you’d want everybody to try to reach the point of minimum health risk.<\/p>\n

And yet, it doesn’t seem like that’s what was done. Or if it was done, it wasn’t done terribly well, as there are at least two measures by which the range currently being called “normal” is a higher risk than the range currently being called “overweight.”<\/p>\n

So how did<\/strong> they pick the current value? It’s not some graven-in-stone number that’s been handed down through the generations, I know that, as nobody talked about “BMI” back when I was in high school, and I remember at least two rounds of news stories over the last fifteen or twenty years talking about the government lowering the values considered “normal.” But if they didn’t take the sensible empirical appoach (they can’t have, otherwise the recent studies wouldn’t be publishable), what did they do?<\/p>\n","protected":false},"excerpt":{"rendered":"

Over at Pure Pedantry, Jake has a nice post about a study showing that the ever-popular Body Mass Index measure is not a good predictor of the risk of heart disease. He’s got a lot of details about the study, including this graph of risk vs. BMI: Now, here’s the thing. This is the second… Continue reading What Do You Mean by Normal?<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"1","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[33,45,11],"tags":[],"class_list":["post-521","post","type-post","status-publish","format-standard","hentry","category-in_the_news","category-medicine","category-science","entry"],"_links":{"self":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts\/521","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/comments?post=521"}],"version-history":[{"count":0,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/posts\/521\/revisions"}],"wp:attachment":[{"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/media?parent=521"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/categories?post=521"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/chadorzel.com\/principles\/wp-json\/wp\/v2\/tags?post=521"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}