Trends in thin body stature among Japanese female adolescents, 2003-2012

Background: The past decades have witnessed a steady increase in thin body stature associated with unhealthy dieting among Japanese female adolescents. The most recent trends in thinness, however, have not been reported. Aim: To describe changes in the distribution of body mass index (BMI) of Japanese female adolescents, from 2003-2012. Subjects and methods: This study examined BMI distribution changes in 2541 relatively affluent Japanese girls, aged 12.5-17.5 years, during 2003-2012. The 2003 and 2004 data were combined and compared to the combined 2011 and 2012 data. Tukey mean-difference plots were used to study the direction and magnitude of shifts in BMI distributions. Results: Prevalence of thinness (BMI 55th percentile of the 1978-1981 references) has progressively increased from 2.0-5.7% in 2003-2004 to 3.5-7.8% in 2011-2012 in Japanese girls. The downward shift in BMI was larger in 12.5-14.5 year olds than in 15.5-17.5 year olds and more prominent in the lower BMI spectrum. Conclusion: The trend towards thinness has continued in Japanese girls during the past decade. The distribution of BMI suggests thinner and younger sub-groups of girls are more susceptible to this trend.