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 (EI) 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 EI 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 EI/RMR ratio to assess the accuracy of EI reporting. This study defined under-reporters as those with an EI/RMR of ≤ 1.34 and over-reporters as those with an EI/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 EI/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 EI is more frequent than over-reporting among Iranian women. Among various factors that may affect the accuracy of EI reporting, age and anthropometric characteristics might have a significant effect.