For years, the message was simple: too much body fat is a bad thing.
In the extreme, that’s still true. Severely obese people are still at higher risk of a litany of ailments. But recently, a more nuanced view has emerged. Maybe a little pudginess isn’t such a bad thing. In fact, some people may be healthier because of it.
For a little over a decade, Katherine Flegal has been poring over health data as it relates to people’s weight. What she and her colleagues found surprised her—and others.
Here’s Harriet Brown, reporting for Quartz:
Flegal found the lowest mortality rates among people in the overweight to mildly obese categories. It’s true that these groups are slightly more likely to suffer from heart disease and some other life-threatening conditions in the first place. But many factors influence the likelihood of a person getting heart disease. And a strong link between weight and disease only emerges among people with severe obesity. So taken at face value, the results seemed to be showing that a little extra weight is genuinely beneficial.
Two years ago, a large meta-analysis of 97 studies showed that people with an “overweight” BMI were 6% less likely to die. It jibed with another, slightly earlier study , which noted that the effect of extra weight increases as people age, too. That study had produced a series of U-shaped curves that plotted body-mass index against risk of death. As people grow older, the trough of the curve—the BMI at which people are least likely to die—moves into ever higher BMIs. By the time a person is in their 70s, the statistically optimal BMI is around 26, or solidly in the “overweight” category.
These findings have certainly found their detractors, though as Brown notes in her article, the evidence increasingly supports Flegal’s so-called obesity paradox.
Our understanding of relationship between weight and health is clearly more complex and nuanced than it was in the 1960s when the standards for healthy weight were first codified. We’re understanding how the health of people with different ethnic backgrounds are affected by weight, for example, and people of different ages. As we grow more sophisticated in our studies, don’t be surprised if things change further.
Photo credit: Paolo Kizette Cimenti/Flickr (CC BY-NC-ND)