High protein and low carb food.
Human are still evolving according to their environments and culture. Agriculture societies like those in China or Europe will produce carbon-hydrate dependent metabolism. So this European studies might fit people of agriculture society. But hunter-gather society depends on total different food which often has very little carb. Such people include Mongolian or Eskimos who are almost pure carnivores (meat-eater). For these people, high-protein and low carb food might be most healthy ones which fit their metabolism better.
This might explain why people of recent hunter and gatherer societies like Hawaiian, American Indians, and African often have higher incidence of diabetes because their metabolism is not evolved to handle high carb food yet.