Encouraging news for some touches off a debate over what statistics can – or can’t – tell us.

As most people around the nation were making their New Year’s resolutions to lose weight and get fit, a study came out in the Journal of the American Medical Association that surprised some – and perhaps delighted others. According to Dr. Katherine Flegal of the National Center of Health Statistics (and the author of the study), people with higher body mass indexes demonstrated a 6 percent lower risk of early death than their more slender counterparts. In other words, the study suggests that overweight people are statistically more likely to outlive skinny people.

About one-third of Americans fall into the weight category Flegal was studying – those with a BMI between 30 and 35. She accounts for the surprising statistic by suggesting that larger individuals may be more likely to receive “optimal medical treatment, cardioprotective metabolic effects of increased body fat, and benefits of higher metabolic reserves.” However, people categorized as “grossly obese” (with a BMI of 35 and up) were 29 percent more likely to die early than their slimmer contemporaries.

The research touched off debate among experts. Walter Willet, an epidemiologist at the Harvard School of Public Health, called the research “rubbish” in an interview with NPR and said that it was misleading because it doesn’t account for people who have lost weight because they are ill, and doesn’t account for the chronic illnesses from which overweight people may be suffering during those extra years, such as diabetes, heart disease and stroke.

Amid both the victorious comments and disparaging remarks that followed the study’s release, one New York Times editorial asked that readers simply look at what statistics can tell us – or not. Written by law professor Paul Campos, author of “The Obesity Myth: Why America’s Obsession With Weight is Hazardous to Your Health,” the piece describes observational studies in the following manner: “[They] merely record statistical correlations: we don’t know to what extent, if any, the slight decrease in mortality risk observed among people defined as overweight or moderately obese is caused by higher weight or by other factors. Similarly, we don’t know whether the small increase in mortality risk observed among very obese people is caused by their weight or by any number of factors, including lower socioeconomic status, dieting and the weight cycling that accompanies it, social discrimination and stigma, or stress.” There is a historical basis for “facts” being enlisted to legitimize cultural obsessions, Campos writes. 

If you have followed the coverage of this recent study, have you been encouraged, or simply taken it with a grain of statistical salt? Perhaps most importantly, is it responsible – as many news outlets have done – to lead with headlines such as “Why being overweight could be a lifesaver,” despite the complexities of making such a claim?