Self-reported BMI was generally reliable for predicting the number of overweight Japanese children and adolescents. There is slight discrepancy, however, between self-reported BMI and measured BMI, and self-reported BMI should be used with caution, keeping the variance and concordance rate in mind.

BackgroundCutoffs based on percentage overweight (POW) are used for screening students in Japan; however, body mass index (BMI) is more common in the rest of the world. To screen for risk factors related to obesity among Japanese primary and secondary school students, we compared fasting and postprandial values, and the receiver operating characteristic (ROC) curves for the POW and BMI criteria.MethodsThe subjects were students aged 10 and 13 years living in Shunan City, Japan between 2006 and 2008 (n = 6566). POW and International Obesity Taskforce (IOTF) BMI criteria were used to screen for obesity-related risk factors. The lower (20%, 18-year-old equivalent: 25 kg/m2) and higher (50%, 18-year-old equivalent: 30 kg/m2) cutoffs were examined, and ROC curves were drawn.ResultsFasting cholesterol levels were higher than postprandial levels. The prevalences of overweight/obesity were 6.6% to 10.0% using the lower cutoff and 0.6% to 5.0% using the higher cutoff. Among overweight subjects under fasting conditions, dyslipidemia was present in 12% to 52%, hypertriglyceridemia in 29% to 54%, hyperglycemia in 11% to 21%, and hypertension in 15% to 40%. Although the use of the lower and higher POW cutoffs resulted in lower sensitivity and the higher specificity, the POW and BMI ROC curves largely overlapped. However, for girls aged 10 years, the POW curve for ≥3 risks factors was lower than that of the latter (P = 0.013).ConclusionsFor Japanese aged 10 and 13 years, both BMI and POW are useful for risk factor screening. However, subjects may be misclassified with dyscholesterolemia if postprandial blood samples are used.

Questionnaires may be useful in epidemiological studies for ranking physical activity levels of adolescents, such as a confounding factor for other lifestyle surveys, but these surveys are less accurate for younger children.

The FTO gene is associated with the early onset of overweight in the Japanese population as well as in European populations. The results suggest that obesity-related risk factors in fifth and eighth graders appear because of their overweight status.

No abstract