Cachexia is the most common paraneoplastic syndrome of malignancy and is characterized by anorexia, early satiety, severe body compositional change with weight loss, adipose and muscle loss, weakness (asthenia), anemia, and edema. Cause of death in as many as 20% of patients with cancer is associated with tumor-induced and treatment-related malnutrition and inanition. Early diagnosis of cancer malnutrition often is missed because of lack of attention by the oncology team. The importance of understanding the basics of nutritional oncology by the entire healthcare team (physician, nurse, pharmacist, dietitian, social worker, physical and speech therapists) and the patient and family is outlined with practical interventions being specified. An algorithm for an optimal nutritional approach in patients with cancer is included, with emphasis on early diagnosis and intervention for maintenance of nutritional, body compositional, and functional status of the oncology patients. Quality-of-life issues, pharmacologic intervention in cachexia, and necessity of cooperative oncology group involvement in nutritional oncology are discussed.