Surgical patients with a chronic energy deficit display a particulare metabolic situation known as chronic shock, marked by deficient utilisation of energy. The picture is related to functional disorders of the cell enzymes, following incomplete resynthesis due to the lack of substrates. The main features are: a) lactic metabolic acidosis due to anaerobic oxidation, usually with insufficiency of the Krebs cycle; b) exaggerated protein catabolism, due to utilisation of amino acids as the energy substrate; c) incomplete utilisation of the (mostly endogenous) substrates available, with lactacidaemia, aminoacidaemia, and increased lipidaemia. A rational form of treatment is proposed after careful analysis of these features and their corresponding clinical phenomena.