Nutritional rehabilitation increases resting energy expenditure without affecting protein turnover in patients with cystic fibrosis

The effect of nutritional rehabilitation on several nutritional parameters was studied in eight malnourished patients with cystic fibrosis during the first year after gastrostomy tube insertion. Body composition was studied by fat skinfold measurements and by total body potassium count, resting energy expenditure (REE) by indirect calorimeter, and protein turnover by a single dose administration of [¹⁵N]glycine. Weight gain was accompanied by a significant increase in the various body compartments: Weight 41.4 ± 7.5 to 46.1 ± 8.4 kg (p < 0.0002), fat body mass 5.6 ± 2.8 to 7.7 ± 3.4 kg (p < 0.005) and fat-free body mass (FFBM) 35.7 ± 6.3 to 38.3 ± 6.9 kg (p < 0.0003). REE increased significantly per kg of body weight as well as per kg of FFBM. No significant differences were found in protein turnover during refeeding nor in pulmonary function. We conclude that nutritional support restores body composition, but is accompanied by an increase in energy expenditure. This increase could not be attributed to increased protein turnover.