Underreporting of energy intake among Japanese women aged 18–20 years and its association with reported nutrient and food group intakes

Abstract

OBJECTIVES To evaluate the ratio of energy intake to basal metabolic rate (EI/BMR) among young female Japanese adults, and to compare the lifestyle and dietary characteristics between relatively low and high reporters. DESIGN Dietary intakes were assessed over a 1-month period with a validated, self-administered, diet history questionnaire, and lifestyle variables were assessed by a second questionnaire designed for this survey. The ratio of EI/BMR was calculated from reported energy intake and estimated basal metabolic rate. SUBJECTS In total, 1889 female Japanese university students aged 18-20 years who were enrolled in dietetics courses. RESULTS Ninety-five per cent of the subjects were classified into a non-obese group (body mass index (BMI) <25 kg m(-2); mean+/-standard deviation (SD): 20.8+/-2.6 kg m(-2)). EI/BMR was 1.43+/-0.40 (mean+/-SD). Sixty-eight per cent of the subjects showed an EI/BMR level below the possibly balanced value of 1.56, 37% showed EI/BMR below the minimum survival value of 1.27 and 2% of the subjects showed EI/BMR exceeding the maximum value for a sustainable lifestyle of 2.4. BMI, body weight and BMR decreased significantly with the increase in EI/BMR (P<0.001). The percentage of energy from carbohydrate was significantly higher, whereas those from fat and protein were significantly lower, among the lower EI/BMR groups. As for food groups, a significantly declining trend from the lowest to the highest EI/BMR groups was observed for cereals. CONCLUSION Underreporting, rather than overreporting, of energy intake was predominant in this relatively lean Japanese female population. BMI was the most important factor affecting the reporting accuracy of energy intake.