Association between Poor Chewing Status and Increased Waist Circumference: A One-year Longitudinal Study

Background: This longitudinal study aimed to investigate the relationship between self-reported chewing status and increases in waist circumference (WC) after 1 year in 10,870 Japanese adults who had received health checkups. Subsequently, 8,068 participants were included in the final analysis at follow-up. Methods: Chewing status was evaluated using a self-reported questionnaire at baseline; 1,080 (13%) respondents were diagnosed as having poor chewing status. We defined an increase in WC of ≥ 5 cm after 1 year as an unhealthy increase; in total, 613 (7.5%) respondents met this criterion. Results: After adjusting for age, gender, WC, body mass index (BMI), and chewing status, an increase in WC ≥ 5 cm was found to be positively associated with gender (females: odds ratios [ORs]: 1.206; 95% confidence intervals [CIs]: 1.008–1.443), WC (ORs: 0.967; 95% CIs: 0.954–0.981), BMI (≥ 25 kg/m2; ORs: 2.194; 95% CIs: 1.715–2.808), and chewing status (poor; ORs: 1.356; 95% CIs: 1.084–1.697). Conclusions: These findings suggest that self-reported poor chewing status is associated with increases in WC after 1 year in Japanese adults.