This blog is intended to go along with Population: An Introduction to Concepts and Issues, by John R. Weeks, published by Cengage Learning. The latest edition is the 12th (it came out in 2015), but this blog is meant to complement any edition of the book by showing the way in which demographic issues are regularly in the news.

If you are a user of my textbook and would like to suggest a blog post idea, please email me at: john.weeks@sdsu.edu

Wednesday, January 2, 2013

Does Being Overweight Really Lower Your Risk of Death?

A very deceiving headline popped up in the New York Times today to the effect that "Study Suggests Lower Mortality Risk for People Deemed to Be Overweight." One has to go into the fifth paragraph of this story to realize that the findings are not what they seem. This is not a case of bad science, but rather a case of a journalist wanting to be sensationalist. The story comes from a new paper published in the Journal of the American Medical Association (JAMA), which does not report new research, per se, but rather analyzes the results of more than 100 studies looking at mortality risks associated with differing levels of body mass index (BMI). The title of the published paper is: "Association of All-Cause Mortality With Overweight and Obesity Using Standard Body Mass Index Categories: A Systematic Review and Meta-analysis." There is obviously nothing sensational in that. JAMA produced a news release with a more informative headline: "Higher Levels of Obesity Associated With Increased Risk of Death; Being Overweight Associated With Lower Risk of Death."  This states the authors' full conclusions, rather than only the second part, which wound up constituting the NY Times headline. So, you can see that this is like those classic intro psych class experiments where you start a rumor at one end of the room and as each person passes on the information to the next person, the content is altered.

Here's the bottom line: Being obese is not somehow better for your health. What the authors did find, however, was that people who are considered overweight, but not obese, by current definitions of BMI, did have lower mortality levels than those people with lower BMI. Why?
...it is possible that overweight or somewhat obese people are less likely to die because they, or their doctors, have identified other conditions associated with weight gain, like high cholesterol or diabetes.
“You’re more likely to be in your doctor’s office and more likely to be treated,” said Dr. Robert Eckel, a past president of the American Heart Association and a professor at University of Colorado.
At the same time, the research suggests that not all fat is bad for you and that perhaps the BMI categories need to recalibrated a bit. Being skinny is not necessarily healthier than what we currently think of as being slightly overweight. As the Greeks famously advised--everything in moderation. 

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