Prevalence and trends of underweight and BMI distribution changes in Japanese teenagers based on the 2001 National Survey data.
BACKGROUND
Excessive thinness has been glamorized among Japanese adolescent girls, and unhealthy dieting to lose weight has become a popular practice among them. The prevalence of underweight in contemporary Japanese girls in comparison with that of boys, however, remains to be studied.


OBJECTIVE
The purpose of this study was to determine the prevalence and trends of underweight in contemporary Japanese teenagers of both sexes using nationally representative cross-sectional data.


METHODS
Underweight was defined as BMI < 3rd percentile by age and sex of the 1978-1981 reference population as previously reported. These reference values were compared with BMIs of the contemporary population based on the 2001 Cross-sectional National Survey data of Japanese teenagers (215 972 boys and 216 496 girls).


RESULTS
The prevalence of underweight was approximately 2-3% in junior high school students of both sexes, 12.5-14.5 years of age, approximately 3% in senior high school students of both sexes, 15.5-16.5 years of age, and approximately 4% in senior high school students of both sexes, 17.5 years of age.


CONCLUSIONS
The prevalence of underweight decreased among Japanese teenage students of both sexes during the past decades. Female preponderance in the prevalence of underweight was not confirmed.
Inokuchi
Mikako
M
Department of Pediatrics, Keio University School of Medicine. Tokyo, Japan.
Matsuo
Nobutake
N
Takayama
John I
JI
Hasegawa
Tomonobu
T
D000293:Adolescent; D017677:Age Distribution; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D011159:Population Surveillance / Q000379:methods*; D015995:Prevalence; D012016:Reference Values; D017678:Sex Distribution; D013851:Thinness / Q000453:epidemiology*