All living beings need energy in order to function. Carbohydrates, fats, and proteins, in any reasonable combination, are the sources of energy, or fuel, for the human body.
Despite their importance to the body as the dominant source of energy, foods rich in carbohydrates are regarded by many people in our society as inferior. Yet they are enjoyable to eat and are the most economical of all nutrients to produce, to store, and to buy. With the high cost of meat and other protein foods, money-saving carbohydrate foods will probably continue to gain in popularity. Most nutrition scientists agree that the 12 percent of daily calories obtained by Americans from protein is about the right amount but that the 42 percent obtained from fat should perhaps drop toward 30 to 35 percent, and the 46 percent obtained from carbohydrates should increase. They suggest including more complex carbohydrates in the diet while reducing refined sugar intake.