The state of art of artificial nutrition in depleted cancer patients is reviewed in brief. Because cancer cachexia cannot be equated to simple nutrient deficiency but is due instead to complex metabolic abnormalities, the nutritional effects of total parenteral (TPN) and enteral (EN) nutrition are more limited than in starving subjects. TPN and EN usually prevent further deterioration of the nutritional status, although they are not able to fully reverse a state of depletion. There is evidence that quantitative and qualitative modulation of certain nutrients may obtain better results because of a favorable impact on host metabolism. Research in this field is fully warranted. Moreover, the effects of some substrates on tumor metabolism and tumor growth require further investigation to define a nutritional regimen able to maintain the host metabolism with minimum stimulation of tumor growth.