Answer:
Those are the three main nutrients the body uses to function.
Carbs are broken down into Glucose, which is used to supply energy to the cells, and any extra is stored in the liver.
Protein is broken down into amino acids, which is used to build muscle and make other essential proteins that help the body function.
Fat gets broken down into fatty acids to make hormones and cell linings, extra is stored in fat cells.
They are all essential to help your body function and to make you have energy and feel good. :)