Yes, there are a number of efforts around the world. One I can point to specifically is called the community guide, which is organized by the Centers for Disease Control in the U.S., whose sole purpose is to take the whole bulk of literature that's out there and ask what we can actually learn from that literature about how to intervene.
Particularly on the physical activity side, there's enough data now to know that a number of different kinds of interventions around physical activity actually have an impact on people's behaviour--and this is generically, beyond childhood obesity--for example, things like comprehensive programs; quality daily physical education; point-of-decision prompt, so that when you're at an elevator it says if you take the stairs, you'll actually burn this many more calories.
On the nutrition side, unfortunately, the database is really much weaker, and although there are some good studies that show there are ways to intervene in nutrition in schools and things like that, there isn't enough data yet for that body to actually make strong recommendations about how to intervene. It really speaks to a gap in our understanding about intervention.
So while we know something and we know enough to know that we need to act, one of the really important things is that when we do act we make sure we also learn from those actions in order to be able to feed our understanding in an ongoing way.