The objective of the presented work is to evaluate to what extent the CO2 production and O2 utilization and energy metabolism at rest (REE) are influenced by an excessive nutrient intake and to what extent by the composition of enteral nutrition. REE, CO2 production and O2 utilization were investigated in 9 patients on complete enteral nutrition by indirect calorimetry in four modifications: I - nutrition with 40 %kJ fat in a ration 1.2x the energy output at rest at the onset of the trial; II - 40 % kJ and high energy intake (2.4x energy output at rest; III -60 % kJ fat in ration of 1.2x energy output at rest; IV - 60 % kJ fat and energy intake 2.4x energy output at rest. At 40 % (I) and 60 % (III) fat content in a caloriocally adequate diet the energy output at rest, the C O2 production and O2 utilization did not differ (mean ± SD: 1438 ± 264.1 kcal/24 h, 179 ± 31.6 nl/min, 209 ± 38.1 ml/min vs. 1431 ± 342.7, 190 ± 54.2, 207 ± 46.5). Comparison of modifications II and IV revealed a significant (p < 0.05) increase of CO2 production on a diet rich in carbohydrates (218 ± 52.0 vs. 202 ± 42.3). The energy output at rest (1674 ± 389.6 vs. 1661 ± 378.7), nor O2 production (240 ± 54.5 vs. 242 ± 55.4) changed. Overfeeding with 40 % fat (II) as compared with (I) led to a rise of the energy output at rest (p < 0.05), O2 utilization (p < 0.05) and CO2 production (p < 0.01). Overfeeding with lipids (IV) led as compared with III to a rise of the energy output at rest and O2 utilization; CO2 production did not change. Conclusion: The composition of enteral nutrition according to the described modification does not influences the energy output at rest, O2 utilizatiom and CO2 production under conditions of an adequate energy intake. In case of an excessive nutrient intake nutrition with 60% fat does not lead to an increase of CO2 production.

        Key words: Weaning - Chronic obstructional lung disease - Energy expenditure at rest - Enteral nutrition - Indirect calorimetry - Overfeeding