Energy and substrate metabolism in patients with active Crohn's disease.

The aim of the study was to evaluate the possible contribution of changes in energy metabolism and substrate oxidation rates to malnutrition in Crohn's disease and to assess the effect of enteral nutrition on these parameters. Energy metabolism was evaluated by indirect calorimetry in 32 patients with active Crohn's disease and 19 age- and sex-matched healthy individuals. Measurements were done in the postabsorptive state. Seven out of 32 patients received enteral nutrition via a nasogastric tube. In these patients, resting energy metabolism was determined at d 0 (postabsorptive), 7, 14 (during full enteral nutrition) and 15 (postabsorptive). Resting energy expenditure was not significantly different between patients and controls, whereas the respiratory quotient (RQ) was lower in patients (0.78 +/- 0.05 vs. 0.86 +/- 0.05; P < 0.05). During enteral nutrition in 7 patients with Crohn's disease, the RQ increased on d 7 compared with d 0 and remained high even after cessation of enteral nutrition (d 0, 0.78 +/- 0.03; d 7, 0.91 +/- 0.04; d 15, 0. 84 +/- 0.05; P < 0.05; d 7 and 15 vs. d 0). No effects of enteral nutrition on resting energy expenditure were found. Active Crohn's disease is associated with changes in substrate metabolism that resemble a starvation pattern. These changes appear not to be specific to Crohn's disease but to malnutrition and are readily reversed by enteral nutrition. Enteral nutrition did not affect resting energy expenditure. Wasting is a consequence of malnutrition but not of hypermetabolism in Crohn's disease.