> The only country 1st world country not to have really obese people is Japan (~5% obese ~20% overweight). (~35% obsese ~70% overweight US) and I'd wager a large part of that is the fact that kids cook for themselves in school so they learn early what a reasonable meal is.
There might also be a genetic factor, why japanese are less obese or overweight, because the difference for diabetes patients between US and japan is a lot smaller.