Kids need to exercise more and get to bed earlier, it is alright blaming the salt content in food etc. but getting kids out and about whether at swimming, sports or just out on their bikes more would help greatly. Kids also need to get to bed earlier, xbox's and playstations mean kids are sitting up longer which invariably means they are eating late at night, if you want to avoid getting overweight stop eating after 7pm!
Kids need exercise, of that there's no doubt, but they also need parents as role models showing them that going out for a walk/run/cycle/swim is a normal thing that normal people do, not just the lycra clad 'fitness fanatics'.
Also,
processed food is everywhere you go. Even the milk, bread and what not is processed to an extent, never mind the preprocessed package meals pumped full of MSG, salts, sugars and fats. You can't even go to a butchers now where the bacon and chicken fillets aren't pumped full of some shít or other.
Some of this is to keep the cost of food down, but at what expense to our long term health?