Which nutrient has the least amount of energy and which nutrient can be considered to have the maximum energy density?

The nutrients our body can get energy for the various
metabolic processes are carbohydrates, proteins and fats. Carbohydrates can be
substituted as energy sources by proteins and fats and this makes it possible for a
person to survive even if no carbohydrates are
consumed.

Carbohydrates which can be digested provide 3.75
kilocalories of energy per gram, proteins that our body is able to digest provide 4
kilocalories per gram and fats contain 9 kilocalories per
gram.

This would make carbohydrates the nutrient which
provide the body the least amount of energy per gram and fats the nutrient which provide
the body with the maximum amount of energy per gram.