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At this time of year we're surrounded by media stories about weight: weight loss, the obesity epidemic, dieting, celebrity diets, on and on and on. As one journalist pointed out a few years ago, obesity has become like catnip for news.
So when a new study on weight--especially one on childhood obesity--is published just after New Year's, it's pretty much guaranteed a lot of play. The study I'm talking about here was just published in the prestigious Journal of the American Medical Association; its title is "Effect of a School-Based Water Intervention on Child Body Mass Index and Obesity."
The study analyzed data from elementary and middle schools in New York City that installed water dispensers in their lunchrooms, and concluded that those dispensers "decrease the prevalence of childhood obesity," in the words of lead investigator Amy Ellen Schwartz. The study has been covered in more than a dozen outlets so far, including Medscape, with headlines like "'Water Jets' May Stem Tide of Student Obesity."
I wonder how many of the journalists reporting on this have actually read the study rather than the press release announcing the study's findings. If they had, they would have seen that five years after the water jets were installed, the standardized BMI for boys dropped (drum roll, please) a whopping 0.025 percent, and the BMI for girls dropped 0.022.
Not exactly earth-shaking results. In fact you'd be hard-pressed to say this qualifies as stemming the tide of obesity, or decreasing the prevalence of childhood obesity, or any of the other rather grandiose conclusions drawn from the study.
Even worse, no one mentions the fact that this finding is a correlation and that there is zero evidence that installing water jets in school lunchrooms makes kids even a tiny bit thinner. Maybe it does; maybe it doesn't. There are many other factors that could have produced the same (minuscule) result. And rates of childhood obesity have been declining for the last 10 years, though this study used a control group of schools. But there's no way to establish causality from this research.
Giving kids more access to water at lunch is a good thing, but not because it makes you thin, or because it "stems the tide of student obesity," neither of which is true as far as we know. Water is good for us, and many kids (and adults) are mildly dehydrated much of the time. In focusing so intently on a possible weight-loss effect, the study is posing the wrong question. And in overselling the study's findings and making assumptions that are not supported by the evidence, journalists are also posing, and answering, the wrong questions.
If I had a big research budget, instead of spending thousands of dollars looking at whether water dispensers can cause weight loss, I'd spend that money looking at ways to make kids healthier. I'd develop programs to deal with food insecurity, to bring farm-fresh food into schools, to stop bullying and stigma and discrimination, all of which hurt the health of both kids and adults.
I'd look at how to make people healthier, not thinner. I'd worry about the health of all kids, not just the fat ones. And I'd teach other journalists to report on the actual research, not on what their editors wish it said or what the press release said or what they think sounds good.
