Cross-sectional and longitudinal associations between energy intake and BMI z-score in European children

Background: Evidence for the effect of dietary energy on BMI z-scores in young children is limited. We aim to investigate cross-sectional and longitudinal effects of daily energy intake (EI) on BMI z-scores of European boys and girls considering growth-related height dependencies of EI using residual EI. Methods: To investigate cross-sectional and longitudinal effects of daily energy intake (EI) on BMI z-scores of European boys and girls considering growth-related height dependencies of EI using residual EI. Methods: Subjects were children aged 2-< 10 y old (N = 2753, 48.2 % girls) participating in the IDEFICS (Identification and prevention of Dietary-and lifestyle-induced health EFfects In Children and infantS) baseline and follow-up examination. Usual EI (kcal/day) was calculated based on the National Cancer Institute-method excluding subjects with implausible reported EI. Effect of age, height and sex-adjusted residuals of EI on BMI z-score was investigated stratified by baseline age-group (2-< 4 y, 4-< 6 y, 6-< 8 y and 8-< 10 y) cross-sectionally using linear regression models adjusted for relevant confounders (crude model: age, sex, country; fully adjusted model: plus parental ISCED level, parental BMI, screen time; subgroup analysis: plus objectively measured physical activity). Longitudinal associations were estimated between changes in (Delta) residual EI per year and Delta BMI z-score per year with adjustments analogously to the cross-sectional models but with additional adjustment for residual EI at baseline. Results: Cross-sectionally, positive associations were observed between residual EI and BMI z-score for the full study sample, for boys and in older (>= 6 years) but not in younger children in the crude and fully adjusted model. Longitudinally, small positive associations were observed between Delta residual EI per y on Delta BMI z-score per y for the full study sample and in 4-< 6 y olds in the crude and fully adjusted model. Conclusion: In conclusion, EI above the average intakes for a certain sex, age and height are weakly associated with BMI z-scores in European children. Residual EI may be considered as a useful exposure measure in children as it accounts for growth-related changes in usual EI during childhood.