I disagree. On average, the Japanese get over 80% of their calories from carbohydrates, and over half from rice alone. They're also the thinnest of all economically developed people in the world, and have the greatest longevity.
Furthermore, in the 1970's the Japanese diet was even more dominated by carbohydrates and people the populace was even thinner. At that time, 75% of calories were supplied by rice, and close to 90% by carbohydrates in general.
The phenomena isn't restricted to Japan either China is also seeing increasing obesity, heart disease and diabetes as its people living in top-tier and second tier cities adopt diets higher in fat and higher in protein.
The current American diet is actually unusually high in protein and fat by historical (i.e. pre-WWII) standards.