Macronutrients are important both as an energy source and in providing structural building blocks for everything in our cells. There are 3 macronutrients
Carbohydrates - Are the preferred energy source for the body. They are also used to create some structural elements in and around our cells.
Fats or Lipids - Fats are a source of energy that is stored for long term needs. They and also provide protection for vital organs.
Protein - The primary role of protein as a macronutrient is to provide amino acid building blocks for the cells. Protein can also be used as an energy source when carbohydrate supplies are depleted through a process called glyconeogenesis.