It is best to get most of these calories from complex carbohydrates (starches) and natural sugars. In addition to calories, complex carbohydrates provide vitamins, minerals, and fiber. To increase your intake of complex carbohydrates and healthy nutrients: 1  Eat fruits and vegetables.t is best to get most of these calories from complex carbohydrates (starches) and natural sugars. In addition to calories, complex carbohydrates provide vitamins, minerals, and fiber. To increase your intake of complex carbohydrates and healthy nutrients: 1  Eat fruits and vegetables.