Components of the Diet Associated with Child Adiposity: A Cross-Sectional Study

Abstract

Objective: This study sought to determine which components of youths' diets were related to adiposity while controlling for potential often-neglected confounders such as moderate to vigorous physical activity (MVPA) and dietary reporting error. Secondary goals of this study were to determine the extent to which MVPA confounded the associations between diet and adiposity and whether associations between diet and adiposity would differ depending on reporting error.

Methods: An ethnically diverse urban sample of 342 children aged 9–10 years and 323 adolescents aged 17–18 years were recruited for this cross-sectional study. Body mass index (BMI) and waist circumference (WC) were measured in the school; dietary assessment included three 24-hour recalls via telephone in the evenings, and MVPA assessment included 5 days of accelerometry. Over (n = 68), under (n = 250), or plausible (n = 347) dietary intake reporters were identified with the Huang calculation method. Linear regression assessed the relationship between adiposity indicators (BMI z-score and WC) and components of the diet (energy intake, food groups, macronutrients) after controlling for reporting error, demographic variables, and MVPA.

Results: When dietary reporting error and potential confounders such as MVPA and demographic variables were controlled, energy intake (EI), vegetables, refined grains, total fat, total protein, and total carbohydrate were positively related to BMI z-score and WC and artificially sweetened beverages to WC. MVPA was a significant confounder. For BMI z-score, but not WC, relationships and strength of these relationships differed depending on dietary reporting error group (plausible, underreporter, overreporter).

Conclusions: Among plausible reporters, as expected, EI, refined grains, and all macronutrients were positively related to adiposity; however, artificially sweetened beverages and vegetables, which are low-energy-dense foods, were also positively related to adiposity. Reporting error interfered with associations between diet and BMI z-score but not WC, suggesting WC is a more robust measure of adiposity in relation to diet.

Key words::

• child obesity
• diet
• dietary intake reporting error
• confounding
• physical activity

ACKNOWLEDGMENTS

This research was funded by the National Institute of Health, grant R01 CA 116766. In addition, this work is a publication of the USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas. This project has been funded in part by federal funds from the USDA/ARS under Cooperative Agreement 58-6250-6001. The contents of this publication do not necessarily reflect the views or policies of the USDA, nor do mention of trade names, commercial products or organizations imply endorsement by the U.S. government.

Fig. 1. Scatterplot with predicted lines (based on a fixed portion of the model) for energy intake and body mass index z-score in the total sample, with and without stratification for reporting status.

Table 1. Frequencies (n), Percentages (%), Means (M), and Standard Deviations (SD) and Tests of Differences for Participant Characteristics by Dietary Reporting Bias (Plausible Reporting, Underreporting, and Overreporting)

Table 2. Means (and Standard Deviations) for Physical Activity and Energy Intake by Energy Reporting Status (Plausible Reporting, Underreporting, and Overreporting)

Table 3. Standardized Coefficients from the Mixed-Model Regression of BMI Z-Score on Total Energy Intake and Participant Characteristics

Table 4. Standardized Coefficients from the Mixed-Model Regression of BMI z-Score on Food Group Composition and Participant Characteristics

Table 5. Standardized Coefficients from the Mixed-Model Regression of BMI z-Score on Macronutrients and Participant Characteristics

Notes

Competing interests or conflicts of interest: none.