Does this study make us look fat?

fat_dressWe are all weary of news about obesity, and here comes a rarity – an excellent study that uses pristine methods and accurate descriptions of the worldwide trends.  Sad to say, the message will likely get lost in the sound-bite translation. 

The NEJM study is a crystal clear look at 195 countries, measuring Body Mass Index at the population level and correlating it with the incidence of certain diseases and disabilities.  BMI, as a measure for overweight and obesity in individual people, has its own flaws and controversy.  But at the population level, it is a valid measure and, as these researchers have shown, correlates to important illnesses.

Thus, a country whose average BMI tips toward the higher end has more deaths and more disability related to cardiovascular disease, diabetes, and chronic kidney disease among others.  And the researchers found that as national BMI averages decreased, so did deaths and disability from these diseases.  This is not the same as saying that every individual person with a BMI greater than 25 will lower his risk of cardiovascular (or other) disease by losing weight.  He may have myriad other factors that stress his heart, such as earning a low income or having sub-standard housing.  Those factors don’t change, even if his weight does.

What’s true for a population does not directly translate into what’s true for a single person.   The NEJM study message is that populations with higher average weight-to-height ratios also tend to have higher rates of certain diseases.  We could quickly end the discussion with the usual, “Those fatties just need to put down the fork.”

Or we could do something more interesting: ask what population-level characteristics we can influence and ultimately contribute to better health.   We clearly know that social determinants of health are much more important than biological ones.  Let’s start there.

Fifty years hence, people will probably laugh about obesity, in much the same way we scoff at polio.  (For a terrific and interesting book, try But What If We’re Wrong/ Thinking About The Present As If It Were the Past.  Even opening the book is a challenge due to the title being upside down and backwards, so your first encounter with it is of being wrong.  E-book readers will miss out on this funny experience.)  The obesity solution or treatment or prevention will be as obvious as daylight.  Put this into perspective – we’re struggling with what will become the fodder of jokes for our great-grand-children.   Except that so many people hate puns, I’d say, “Lighten up!”


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