It's both. Other than sweet potatoes, sugar and carbs weren't part of their diet before European contact. In addition to that, they didn't have to work very many hours to satisfy their daily needs. Hour or two fishing, while someone else gathers roots and berries and after that you could sit on your ass and sharpen your spear. Like niggers, they aren't able to acclimate to western society, and western society is actually bad for them.