Malnutrition and the broad spectrum of cancer cachexia frequently occur in patients with malignant disease of all tumour stages and impact on survival and quality of life of patients. Structured screening for the risk of malnutrition with validated tools and nutritional assessment are the prerequisite for adequate nutritional support in cancer patients. In patients receiving tumour directed therapy, the patients diet should meet the requirements to give optimal support, while later on comfort feeding is part of symptom focused palliation. The basis of nutritional support in a malnourished patient is nutritional counselling, and nutritional support can be offered within a step-up approach meeting the patient's needs. A combination of nutritional support with interventions targeting metabolic changes and physical exercise is suggested to treat cancer cachexia.