I know, a cheap headline to draw you in. I apologize.
What I mean to say is,
"No ONE thing will ever prevent childhood obesity",or any obesity for that matter.
In order for any single public health intervention to have an impact on any sort of obesity, it would mean that whatever target the intervention manipulated would have to in and of itself be responsible for a large and significant percentage of the problem.
And therein lies the rub. Our struggle as a society with weight and/or healthy living has more to do with the accumulation of dozens, if not hundreds, of environmental changes where the end result is an environment where the unattended consequence of spontaneously living is weight gain. Simply put, the current pushes us there.
The reason it's important to always keep this in mind is that the likelihood there'll ever be a singular intervention that makes a demonstrable impact is exceedingly low, and that fact is going to bedevil policy makers, researchers and analysts because it's going to be tough for them to make the case, "Yeah, sure, that didn't do much, but we've got to keep doing it anyhow even if there was no demonstrable benefit".
It's that whole twig thing. Effortless to break one. Easy even to break two, three, four, five and more, but get a large pile of small twigs together and eventually you'll get to a point where despite each twig being laughably snappable itself, together they might as well be a log.
Keep that in mind before you pass judgment the next time on the futility of a particular intervention after you read about how a study on intervention "X" didn't seem to make a demonstrable difference on obesity rates, weight changes or eating behaviours.
It's David Katz's single sandbag phenomenon, and if you're surprised that a single sandbag wasn't enough to stop the flood, I think perhaps some remedial Flooding 101 is in order.