Understanding the basics of macronutrients:

Fats: Fats are a rich source of energy and essential functions in the body.  Fats are needed to absorb fat-soluble vitamins including vitamins A, D, E, K.  They are also needed to form hormones and support healthy skin and hair.  Fats are also crucial for brain health.

Protein: Proteins form the major structural components of all the cells of the body.  They also function as enzymes, in membranes, as transport carriers, and as hormones.  Amino acids are the building blocks of protein and as precursors for nucleic acids, hormones, vitamins and other important molecules.

Carbohydrates: The primary role of carbohydrates is to provide energy to all of the cells in the body.  Carbohydrates are also a component of many structures within the body including RNA and DNA.