US FDA nutritional guidelines are based on 2,000 kilocalories a day. Europeans use kilojoules to the same effect.

I’m not sure any food in the USA uses a single calorie as a measurement of anything, because kilocalories make more sense in terms of units of scale in the human diet.

2000000 of anything sounds like a lot, so why not use prefixes to simplify?

Source: https://en.wikipedia.org/wiki/List_of_countries_by_food_energy_intake

According to the FAO, the average minimum daily energy requirement is approximately 8,400 kilojoules (2,000 kcal) per adult and 4,200 kilojoules (1,000 kcal) a child.[3] This data is presented in kilojoules, as most countries today use the SI unit kilojoules as their primary measurement for food energy intake,[4] with the exception of the USA,[5] Canada,[6] and the UK, which use kilocalories or both.

┬⁠─⁠─⁠┬⁠◡⁠ﾉ⁠(⁠°⁠ ⁠-⁠°⁠ﾉ⁠)

That’s a very interesting article, thanks!