Malnutrition in patients with liver cirrhosis is currently associated with abnormal fuel metabolism. The aim of this study was to evaluate changes in energy production and substrate oxidation rates in a group of 26 nonanorectic severely malnourished cirrhotic patients in stable clinical condition after 1 month of an oral diet. Child-Pugh score, nutritional status, energy expenditure, rates of nutrient oxidation, and plasma levels of intermediary metabolites in the postabsorptive phase were assessed before and after 1 month of oral nutrition. Upon entry onto the study, caloric and protein intakes were 40.1 +/- 2.0 kcal/kg and 1.44 +/- 0.8 g/kg, respectively. The Child-Pugh score did not change during the study, whereas nutritional status improved as shown by increased muscular midarm circumference, ([MMAC] P < .02), height-creatinine index (P < .05), triceps skinfold thickness ([TST] P < .01), and fat mass (P < .001). Inflammatory state improved during the study, as shown by the decrease of C-reactive protein ([CRP] P < .01) and orosomucoid (P < .001). The ratio of caloric intake to resting energy expenditure (REE) increased (1.53 +/- 0.06 v 1.66 +/- 0.07, P < .05), as well as the rate of glucose oxidation ([Gox] 73.6 +/- 9.9 v 128.1 +/- 10.3 mg/min, P < .001) and urine nitrogen excretion (6.69 +/- 0.47 v 7.96 +/- 0.48 g/d, P < .02). On the other hand, the rate of lipid oxidation (Lox) decreased (67.3 +/- 3.9 v 47.3 +/- 4.9 mg/min, P < .001) and was correlated with the decrease of free fatty acid (FFA) levels (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)