Factors like food availability, economics, choices, and lifestyle affects how much food people eat around the world. Some people would want to eat more, but they don't have more, others have all the food in the world, but they are worried about their health and appearance.
money mainly and also caring about appearance and being healthy America tends to have a a lot of money and seems to care less about there health either due to laziness or money wise being that they can only afford fast food
Especially in lesser-developed countries, availability of foodstuffs dictates the diet. In some parts of the world, if you want to eat, you either kill it, gather it, or grow it yourself. If it isn't indigenous to your part of the world, you simply don't get it.