The Japanese consume a diet high in carbohydrates, but I don't see them, or their children, growing up sick and obese. As a matter of fact, some of those high carb consuming populations enjoy the highest life expectancy of any people on earth.
The Japanese consume a diet high in carbohydrates, but I don't see them, or their children, growing up sick and obese.
There have been cultures that traditionally ate high-carb diets, without becoming obese. These traditionally ate grains and beans, rather than flour and sugar, and usually fermented them.
It's flour and sugar that are the problem, and I'll challenge you to find a single example of a culture that survives predominantly on refined carbs that isn't sick and obese - and often malnourished at the same time.
As for Japan, their obesity rates have been skyrocketing, as they've adopted western foods:
Obesity on the rise as Japanese eat more Western-style food
Of course, their kids are getting a better start, because their school lunches actually serve food, and insist that they eat it. (As opposed to ours, which consider sugar-and-chocolate flavored milk to be healthy, so long as it is low-fat.):
How Japan’s revolutionary school lunches helped slow the rise of child obesity