Adderall is a combination of an amphetamine and dextroamphetamine. Acting together the pill is absorbed through the intestinal lining and acts as a CNS (central nervous stimulant). When the stomach is empty, Adderall moves to the intestines quicker and with less efficacy loss than when it is allowed to mix with food. Certain foods high in acid content will add to this dampening effect by combining with the active ingredients of Adderall. Adderall will not work at all when the stomach has not digested food within 24 hours, as the acidic digestive juices will destroy the active ingredients before they can be absorbed.