Kalmar "hallaka metabolism" yana nufin rushewar hadadden kwayoyin halitta a cikin halittu masu rai zuwa ma'auni mafi sauƙi, wanda ke haifar da sakin makamashi. An kuma san shi da catabolism kuma shine kishiyar metabolism na anabolic, wanda ya haɗa da haɗakar kwayoyin halitta daga mafi sauƙi. A cikin metabolism mai lalacewa, manyan kwayoyin halitta irin su carbohydrates, proteins, fats suna rushewa zuwa ƙananan ƙwayoyin cuta kamar su glucose, amino acid, da fatty acid, waɗanda za a iya amfani da su don samar da makamashi ko wasu hanyoyin tafiyar da salula.