Associations Between Health Literacy and Underweight and Overweight Among Japanese Adults Aged 20 to 39 Years: A Cross-Sectional Study

Abstract

Background. Both underweight and overweight are public health concerns in Japan. Several studies examined the association between health literacy (HL) and obesity status in the general population; however, there is limited information on young adults. In addition, the association between HL and underweight status has not been extensively investigated. Aim. To examine the association between HL and underweight/overweight status among young Japanese adults aged 20 to 39 years. Method. This study was based on a cross-sectional survey of population-representative adults. HL was assessed using a questionnaire validated in Japanese adults. Body mass index (BMI) was calculated using self-reported weight and height. Participants were divided into two groups by HL score using the median score (lower vs. higher HL). The association between HL and underweight (BMI <18.5) or overweight (BMI ≥25.0) was examined using multinomial logistic regression analyses after adjusting for potential confounders. Results. In total, 476 women and 454 men were included in the analyses. Prevalence of underweight and overweight was 20.8% and 10.3% in women and 8.8% and 20.3% in men, respectively. In women, 45.1% of normal weight, 47.5% of underweight, and 30.6% of overweight had higher HL. Among men, 50.3% of normal weight, 35.0% of underweight, and 44.6% of overweight had higher HL. Bivariate analyses showed no statistically significant association between HL level and underweight/overweight status. Even after adjusting for potential confounders, these associations did not change. Discussion and Conclusion. This study suggests that HL scores may not be associated with underweight or overweight status in Japanese adults.