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Background: To support age-appropriate growth and to prevent and treat malnutrition in children with cystic fibrosis (CF), energy requirements for those children are often set above the requirements for healthy children. Care providers use one of several empirically derived formulas to calculate energy requirements, yet the validity of these formulas has seldom been tested., Objective: We evaluated 6 proposed formulas for calculating energy requirements in children with CF against a total energy requirement for children with CF (TER-CF) derived from measured total energy expenditure, fecal fat energy loss, and the theoretic energy required for age-appropriate tissue accretion., Design: Subjects were children aged 6-8 y who had CF and pancreatic insufficiency. Calculated TERs from each formula were evaluated against TER-CF by using summary statistics, regression analysis, and residual plots., Results: Subjects (n = 53) had suboptimal nutrition and growth status and mild-to-moderate lung disease. The formula that most closely (within 2%) approximated TER-CF was the estimated energy requirement (EER) formula at the active level (EERact). Regression analysis of TER-CF onto calculated TER from each formula yielded the best indexes of model fit for the EERact formula; residual plots of the EERact formula were tightly and normally distributed around zero., Conclusions: The EERact formula should be used to establish TER-CF in children in this age group who have mild-to-moderate CF. Changes in weight, height, and other indicators of nutritional status must be monitored to modify TER-CF as needed to support individual patient care goals.

Background: Suboptimal growth and nutritional status are common among children with cystic fibrosis (CF) and pancreatic insufficiency (PI). A better understanding of energy balance is required to improve prevention and treatment of malnutrition., Objective: Our objective was to characterize energy balance and the reporting accuracy of dietary intake in children with CF by evaluating the relations between energy intake (EI), energy expenditure (EE), fecal energy loss, nutritional status, and growth., Design: The subjects were participants of a 24-mo prospective study of children 6-10 y of age with CF and PI. EE, EI, fecal energy loss, and anthropometric measures were obtained at baseline and at 24 mo., Results: The children (n = 69) had suboptimal growth at baseline (x +/- SD: weight-for-age z score, -0.53 +/- 1.19; adjusted height-for-age z score, -0.67 +/- 1.06; body mass index z score, -0.29 +/- 1.12), and these variables remained suboptimal at 24 mo. The median ratios of EI to EE at baseline and 24 mo were 1.15 and 1.18, respectively, which decreased to 1.09 and 1.10, respectively, when adjusted for fecal energy loss (EI(-FL):EE). At baseline, 7% of subjects were underreporters, 64% were accurate reporters, and 23% were overreporters of energy intake; the percentages were similar at 24 mo., Conclusions: Although EI(-FL):EE ratios were higher than expected at both baseline and 24 mo, this cohort showed only age-appropriate weight gain. Self-reported dietary intake data at the individual level should be interpreted with caution, and weight gain velocity may serve as an objective measure of long-term energy balance.