Relationship between mouthful volume and number of chews in young Japanese females

Objective: Modification of eating behavior in Japan is promoted to prevent overweight and obesity, but the effects of such modifications are unclear. This study aimed to clarify the inter- and intra-individual relationship between bite size and number of chews of food. Design and methods: Subjects comprised of 50 young healthy Japanese women (mean age 19.5 years). Food materials were boiled rice and apple. First, the average bite size and the number of chews per mouthful of food were calculated across the study cohort. The number of chews was counted by the subjects themselves and then self-reported. Correlation between the individual one-bite volume and the number of chews per volume was analyzed using Spearman's rank correlation coefficient. Second, the number of chews for three different sized bites of food (half of one bite, one bite, and one-and-a-half bites) were calculated as a prospective observational study. The number of chews for each of the three volumes of food was compared using one way ANOVA with Bonferroni correction. Results: For both food types, there was a negative correlation between individual mouthful volume and number of chews for both food materials. The number of chews per volume decreased as bite sizes increased. Conclusion: This study demonstrated an inter- and intra-individual relationship between bite size and the number of chews and suggested that smaller bite sizes were associated with more chews per volume of food.