The nutritional status of patients affected by lung cancer is directly influenced by the presence of cancer, which impacts on all aspects of intermediary (protein, carbohydrate, lipid, trace element, vitamin) metabolism, and by other factors such as age, adjuvant cancer therapy and stage of the disease. The greater sensitivity of protein catabolism to nutritional support, in particular to amino acids, could have important implications for the nutritional management of these patients during the period of catabolic stress, with particular emphasis on substrate utilization and energy requirement.