The reason Americans are so fat and crave sweet things is because back in the 70s the government decided fats were bad and took fat out of everything and replaced it with sugar. You can choose to believe they were either well meaning idiots or it was a giveaway to big ag corn producers.

Also, ethnic cuisines in other countries were often adapted to what was cheap and available to people where they were living. Chinese cuisine in Portugal is different from Chinese cuisine in Argentina or the states. The reason Chinese cuisine in the US has diverged so far from its origins, compared to Indian is because Chinese people have been in North America in large numbers for far longer than people from India have. Many Chinese families have been in the US since long before it was possible to ship perishable goods across the Pacific Ocean. You can even see the same process play out with traditional mayo cuisines. The American association of corned beef with Irish immigrants is a good example of this phenomenon. Irish immigrants in New York often lived in proximity to Jewish neighborhoods. They would purchase corned beef from their Jewish neighbors. You couldn't find corned beef and cabbage on a pub menu anywhere in Ireland 30 years ago, but because so many Americans who would visit were perplexed that it wasn't available pub owners put it on the menu for the tourists.