More water means slightly less weight in New York schools
© 2016 Roy Benaroch, MD
A simple, safe, and cheap intervention looks like a good way to help fight obesity in our schools. But not by very much.
A study published January 2016 in JAMA Pediatrics, “Effect of a school-cased water intervention on child body mass index and obesity”, looked at the effects of installing new water dispensers in New York City school cafeterias. 1227 schools, including 1 065 562 students, participated in the observational study, which tracked student weights and BMIs, comparing trends before and after the new equipment was installed.
Those new dispensers are called “water jets” in the study, and I *think* they’re just those typical water cooler things that offices use, with a big jug of water on top and a little flappy valve to get cooled water into a cup below. The study description says they both chill and oxygenate the water “to keep it tasting fresh”, and cost about $1000 bucks each. Furthermore, they “are relatively easy to use” (pretty clever, those New York kids.) The authors pointed out that participants were weighed and measured by PE coaches, whose scale-using skills have “previously been found reliable” (pretty clever, those New York coaches.)
The results: after these water jets became available, there was a statistically significant drop in BMI of about 0.025 points (it was just a touch more effective in boys than girls), and the percentage of children in the schools who were overweight dropped by .6-.9%. (from about 39% to about 38%).
I know, not very impressive. The statistics are solid—whether the authors looked at trends over entire schools, or at trends among individual students before and after water jet availability, these weight parameters did drop. And the drop is, technically, statistically valid and real. That’s how it’s been reported in the media. The New York Daily News said “Water machines available in schools can help kids lose weight.”
But the drop really wasn’t very much. Going from 39% to 38% overweight is good, but I think we ought to try to do better. You can lead a student to water, but studies like this show it’s hard to make them actually lose weight.