© Tammra McCauley, used via Creative Commons license
Source: © Tammra McCauley, used via Creative Commons license

In my last post, I looked at whether Americans are continuing to gain weight, and concluded that the evidence doesn't support that. So let's look at the second big lie about weight and health.

Lie #2: Obesity can take years off your life.

Truth #2: Rarely true. About 10 years ago, Centers for Disease Control epidemiologist Katherine Flegal set out to map the relationship between BMI categories and mortality. They expected to find a linear relationship: the higher a person’s BMI, the greater his or her risk of dying prematurely.

But that’s not what they found. Instead, they discovered what statisticians call a U-shaped curve, with the bottom of the curve—the lowest risk of death—falling around 25 to 27 on the BMI chart, making the risk of early death lowest for those now labeled overweight. People considered “mildly obese” had roughly the same risk of dying as those in the “normal” category. Death rates went up for those on either end of the scale—underweight and severely obese (BMI over 40)—but not by much. “The differences we’re talking about overall are pretty tiny,” explains Flegal. But as soon as her analysis appeared in the Journal of the American Medical Association, the excrement hit the air conditioning. Other researchers claimed her work was shoddy, that she’d left out important data. S. Jay Olshansky, a professor of epidemiology at the University of Illinois-Chicago, responded with a journal article arguing that rising obesity rates would shorten lives by two to five years.

That statistic got a lot of attention, and helped establish the idea that, as countless media outlets went on to report, for the first time in history a generation of children would have shorter lives than their parents. And that prediction is still floating around today, despite the fact that it’s been utterly and thoroughly debunked. As University of Alabama-Birmingham biostatistician David B. Allison, sheepishly told a reporter from Scientific American, “These are just back-ofthe-envelope plausible scenarios. We never meant for them to be portrayed as precise.”

This type of end-justifies-the-means truth-bending is common in the world of obesity research. Last year, for instance, the National Obesity Forum, an influential lobbying group in the United Kingdom that works on behalf of a long list of pharmaceutical companies, admitted to lyingactually admitted it—in its latest report. The authors warned that obesity in Britain was continuing to rise, and that an earlier prediction that half the population would be obese by 2050 was “optimistic and could be exceeded by 2050.” In actuality, rates of obesity in the United Kingdom, as in the United States, have plateaued or diminished slightly. The group knowingly misrepresented the facts “to reach a wider public,” confessed spokesman Tam Fry.

Reports like these, which are grounded in opinion and clear agendas rather than fact, feed an increasingly hostile and confusing public conversation around weight. And it’s hard to understand where they’re coming from. I mean, shouldn’t we be glad to hear that a few extra pounds—or more than a few—might not be so bad for you? Might, in fact, even be good for you under certain circumstances?

NEXT POST: LIE NUMBER 3—BEING FAT MAKES YOU SICK.

About the Author

Harriet Brown

Harriet Brown is the author of Body of Truth: How Science, History, and Culture Drive Our Obsession with Weight—and What We Can Do About It, Brave Girl Eating, and other books. 

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