A brief note from the BMI war front

For those of you who read science news, you’re probably already alert to the fact that news headlines and reports of scientific studies are sometimes distorted, emphasizing one minor or small result over the main findings.  For my part I’m glad that news outlets are interested in reporting on science, and the alert to some study (even if the headline is misleading) is enough to send me to the article.  There I can get the real scoop.

I had one of those experiences this week, this time about a new study out in the British Medical Journal.  I found out about this study from a newsletter (I get way too many newsletters!) from the Harvard School of Public Health.  First, the comparison of headline vs. study results.  Here’s the headline and graphic for the article.

The title reads "leanness combined with healthy lifestyle factors found to be most protective against early death", and the graphic shows a lean female runner's silhouette.

Now, let’s go to the original BMJ article and see what the results say.  They are here:

A screenshot of the results of the BMJ study; the link is included in the article.

What does the above section mean?  Here’s the upshot:

People who engage in “healthy eating”, physical activity, who don’t smoke, and don’t drink will have a lowered mortality risk (regardless of BMI) than those who don’t.  Duh.

People with low BMIs who don’t engage in the above-mentioned “lifestyle” habits have a higher mortality risk than the other groups.  Duh.

So why am I writing about this?  Because the headline in the Harvard School of Public Health newsletter is saying that leanness (combined with healthy lifestyle factors) is most protective.  As if leanness is something we can achieve just by working at it.  As if leanness can be selected as an option.  As if just by trying very very hard, we can be like this:

silhouette of a lean female runner against a sunny amber background

We all know from reading this blog and other sources that bodies vary in lot in shape and size and lots of other features.  We also know that medicine has not yet proposed any effective procedures or medications to reshape those various bodies into ones that look like the one pictured above.  The BMJ article is actually pretty complicated (as population epidemiological articles are wont to be).  There are a host of results, some of which go against the majority view in medicine (and even in public health, I’m sad to say) that leaner is better, full stop.  Those are discussed in the article, and I’ll be dissecting them for a paper I’m working on with my friend Dan (who also reads this blog– hi Dan!). 

But for now, I’ll leave you with this:  beneath the headlines, there’s a host of complex messages.  It’s worth reading multiple sources and digging into the original articles (and reading more wonky and extended analyses on this blog). 

That’s all folks– I’m now off to do the Jingle Ride.  More pics on the FB page later…

A group of cyclists in holiday gear ready for the JIngle ride.

 

 

 

 

 

About catherine w

I'm an analytic philosopher, retooled as a public health ethicist. I'm interested in heath behavior change, particularly around eating and activity, and how things other than knowledge affect our health decisions.I'm also a cyclist (road, off-road, commuter), squash player, x skier, occasional yoga-doer, hiker, swimmer and leisurely walker.

One thought on “A brief note from the BMI war front

  1. Not A Statistician says:

    I hate to tell you this, but we all have a 100% mortality risk. We can to some degree mitigate when the inevitable happens, but it will happen.

    Like

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