抄録
Objective: Irabu Island Elementary School in Miyakojima City has implemented a school lunch program incorporating dewaxed brown rice (DBR) as part of an initiative to address childhood obesity. This study examined five-year trends in obesity prevalence and obesity degree from fiscal year 2022 (R4) through fiscal year 2026 (R8).
Methods: Children who underwent annual school health examinations were included, and data from the five fiscal years were reanalyzed using uniform criteria. Obesity was defined as an obesity degree of ≥20%. Annual changes in obesity prevalence and obesity degree were analyzed for the entire school population and according to obesity severity, sex, and grade. Newly enrolled first-grade children were also analyzed separately.
Results: Overall obesity prevalence was 29.8%, 33.2%, 29.7%, 24.3%, and 25.7% from R4 to R8, respectively. Obesity prevalence was lower in R7–R8 than in R4–R6. Mean obesity degree decreased from 15.67% in R5 to 11.13% in R7 and remained at a similar level in R8 (11.56%). The distribution of obesity degree differed significantly across the five fiscal years (Kruskal–Wallis test, p = 0.026). The proportions of mild and severe obesity were relatively low in recent years; however, the overall distribution of obesity severity categories did not differ significantly across the five years. Mean obesity degree was lower in both boys and girls in R7–R8 than in the earlier years, whereas no consistent downward trend was observed among grades 3– 6. In contrast, obesity prevalence among newly enrolled first-grade children decreased from 33.3% in R4 to 7.7% in R8, accompanied by a decrease in mean obesity degree from 14.32% to 4.15%. Among newly enrolled first-grade children, significant differences across the five years were observed in both obesity prevalence (p = 0.047) and the distribution of obesity degree (p = 0.0026).
Conclusion: Over the five-year observation period, overall obesity prevalence and obesity degree decreased after R5 and remained relatively low in R7–R8. Notably, newly enrolled first-grade children showed lower obesity prevalence and obesity degree at school entry in recent years, before substantial sustained exposure to the DBR school lunch program. These findings cannot be explained solely by the direct effects of DBR consumption at school. Possible contributing factors include the spillover of dietary behaviors from school to families, community health education, health promotion activities by physicians and school physicians, and continuing collaborative efforts involving the medical association, local government, the board of education, and schools. Further studies should examine the factors underlying these changes from a community- wide perspective involving schools, families, healthcare professionals, local government, and the broader community.
