How about: put your kids into sports...any sports. I get that some kids are simply not into sports, but those who want to can find an activity they like.
As someone else on this post said, I too did eat junk food on occasions when I was a kid. I also liked candy and all. But the difference is I moved, I played sports. I wasn't glued to an iPad. So I burned those calories like heck. And when you are an active kids, chances are you also become an active adult. If you don't like sports, just move. Walk with your dog. Stretch. Buy snowshoes in the winter and walk! Oh and yes, eat in moderation. A bit of everything.