Cachexia is defined as an unintended loss of stable weight exceeding 10%. Patients with advanced cachexia express anorexia, early satiety, severe weight loss, weakness, anemia, and edema. Anorexia represents the result of a failure of the usual appetite signals whereas cachexia is the debilitating state of involuntary weight loss. This syndrome, referred to as the cancer anorexia-cachexia syndrome, (CACS) and usually consists of a combination of anorexia, tissue wasting, malnutrition, weight loss and loss of compensatory increase in feeding. CACS represents the result of a complex interaction between cancer growth and host response and is associated with a poor response to chemotherapy and with an increase in drug-related toxicity. In advanced cachexia (mostly in metastatic cancer and terminally disease) any interventions with nutritional suplements are ineffective. Therefore, nutritional support in the reversion of tumor cachexia and in the importance of maintaining patient weight, muscle mass, quality of life, has the exceptional importance, becouse good nutritional status of patients leads to the possibility of more aggressive and longer treatment and thus to longer survival.