It is known to maintain life must food mainly have three types.The first is a carbohydrate,these carbs exist widely in plants and animals,including sugar,starch and fiber molecules,provide the energy for the human body.Carbohydrate also can synthesize biological process must the glucose enzymes.The second is adipose.Fat is more than carbohydrates "enrichment" food energy,but it only as storage can not immediately available energy.The third one is protein.Proteins are made up of carbon,hydrogen,oxygen and nitrogen element composed of macromolecules.Proteins are not mainly used to provide energy,but components necessary to life structure material.