Factors affecting amount of calories?

Question

What factors in foods affects its amount of calories?

Answer 1

Each gram of fat gives you 9 Calories, and each gram of digestible carbohydrate or of protein gives you 4.

Just to confuse you, the Calorie used in food calculations is equal to 1,000 of the calories using chemistry. I'm sorry, that's how it is.

The calorie, in either case, is a measure of energy.