Accuracy of Energy Intake Reporting: Comparison of Energy Intake and Resting Metabolic Rate and their Relation to Anthropometric and Sociodemographic Factors among Iranian Women

Background: This study assesses the accuracy of energy intake (El) reporting and its relation to anthropometric characteristics and sociodemographic factors. In addition, we attempt to identify foods for which under- or over-reporting is more prevalent. Methods: El was assessed for 187 women using a semi-quantitative 168-item food frequency questionnaire (FFQ). Resting metabolic rate (RMR) was measured with an indirect calorimeter. We calculated the El/RMR ratio to assess the accuracy of El reporting. This study defined under-reporters as those with an El/RMR of <= 1.34 and over-reporters as those with an El/RMR of >= 2.4. We measured anthropometric characteristics and collected sociodemographic information. The chi-square test, ANOVA and multiple linear regressions were used for statistical analyses. Results: Among participants, the under-reporting rate was 35.5% and the over-reporting rate was 7.5%. The El/RMR ratio was significantly higher for younger women compared to older women (P < 0.04). Under-reporters had higher weight, waist circumference (WC), body mass index (BMI) and resting metabolism compared to accurate reporters (P < 0.05). Resting metabolism was significantly lower among over-reporters than accurate reporters. After adjusting for energy, the consumption of fish, high-fat dairy products, hydrogenated oil, sweets and coffee was lower, whereas consumption of unsaturated oils, tea, salt and yellow vegetables was higher among under-reporters compared to accurate reporters. Conclusion: Under-reporting of El is more frequent than over-reporting among Iranian women. Among various factors that may affect the accuracy of El reporting, age and anthropometric characteristics might have a significant effect.