Discrepant body mass index: behaviors associated with height and weight misreporting among US adolescents from the National Youth Physical Activity and Nutrition Study.
BACKGROUND
The accuracy and reliability of self-reported height and weight among adolescents in the process of calculating BMI is usually subject to bias. The aim of this study was to determine whether over- and under-reporting of self-reported height and weight existed among US high school students by weight category; if so, to examine anthropometric, behavioral, and demographic factors associated with over- and under-reporting.


METHODS
Data were retrieved from the National Youth Physical Activity and Nutrition Study, 2010, a nationally representative sample (7160 students, grades 9-12). Analysis of variance was performed to determine any significant difference between weight categories in misreporting. Discriminant function analysis and sequential logistic regression were executed to detect behavioral and demographic predictors of reporting accuracy, respectively.


RESULTS
The mean over-reporting of height and under-reporting of weight were 1.1 cm and 1.020 kg, respectively, which underestimated BMI and BMI percentile by 0.671 and 2.734, respectively. Use of self-reported height and weight for BMI calculation overestimated prevalence of healthy weight by 3.8% and underestimated prevalence of obesity by 4.1%. Underweight students under-reported height and over-reported weight, whereas overweight and obese students over-reported height and under-reported weight. Reporting accuracy of females was significantly higher. Weight loss behaviors, both healthy and unhealthy, were associated with BMI underestimation, whereas fast foods and screen time were associated with overestimation.


CONCLUSIONS
Whenever possible, measuring height and weight is essential. However, because many studies must rely on self-reported values alone, additional research should examine the relationships between misreport of anthropometric data and lifestyle features in diverse adolescent samples to better interpret self-reported anthropometric data.
1 Department of Applied Health Science, Indiana University , Bloomington, IN.
Wasantha
W
Jayawardene
David
D
Lohrmann
Ahmed
A
YoussefAgha
D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology; D015982:Bias; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D004032:Diet; D005260:Female; D015438:Health Behavior; D006306:Health Surveys; D006801:Humans; D016015:Logistic Models; D008297:Male; D009043:Motor Activity; D050177:Overweight / Q000453:epidemiology*; D015995:Prevalence; D015203:Reproducibility of Results; D057566:Self Report; D013851:Thinness / Q000453:epidemiology*; D014481:United States / Q000453:epidemiology