One of the nutritional assumptions of most Paleo promoters appears to be that grains that came out of the agricultural revolution promote large carbohydrate overload. Wheat, corn, rice, oats, etc all seem to become glucose very rapidly in the gut. This stimulates large insulin responses. The sugar gets converted to the worst kind of VLDL fat. Heart disease, diabetes, weight gain, and maybe cancer all seem to correlate with these kinds of diets.
My question is why do Asian cultures that eat primarily rice based grain diets not seem to suffer from degenerative Western diseases? Assuming the general nutritional theory behind Paleo is correct, then is maybe rice somehow different than other grains? Are there other factors that can explain away why Japanese who eat rice and fish largely avoid heart disease?