Macronutrients are called macro (big) because we need them in large amounts in our diet. There are three macro-nutrients needed by the human body: fats, proteins and carbohydrates. Macronutrients provide energy to the body. This energy can be measured in kilocalories. Another substance that provides energy, but is not needed by the body, is alcohol.
In addition to providing energy, carbohydrates, fats and proteins provide the raw materials for building the body’s tissues and regulating its many activities.