The Bidirectional Relationship Between Picky Eating and Eating Dinner Alone in Japanese Adolescents: A Longitudinal Study Using RI-CLPM.

: Picky eating often persists from childhood into adolescence, yet its temporal relation to solitary dinners is unknown. We examined the bidirectional links between eating dinner alone and picky eating across three developmental stages in a nationwide Japanese cohort. : A total of 1389 two-parent families from the Japanese Longitudinal Study of Children and Parents participated in the study (grades 4-6 in 2015; grades 7-9 in 2018; grades 10-12 in 2021). Eating dinner alone (four-point scale) was analyzed as a two-part variable (binary ever/never + continuous frequency); picky eating was ordinal (four categories). A Bayesian Random Intercept Cross-Lagged Panel Model (RI-CLPM) with a two-part specification for eating alone was used to assess cross-lagged, autoregressive, and covariate paths; covariates were gender, grade sequence, parental education, and household income. : A single cross-lagged path proved significant: adolescents who ate dinner alone at least once per week in junior high school showed higher-than-their-own-average picky eating in high school, and the reverse paths were non-significant. Picky eating and the binary indicator of eating alone exhibited moderate positive autoregression, whereas the continuous frequency of solitary dinners showed a negative carry-over from Wave 1 to Wave 4, consistent with regression-to-the-mean. Boys, students in higher grades, and adolescents from higher-income households were more prone to solitary dinners, whereas girls exhibited higher trait-like levels of picky eating; parental education showed no significant associations. : Frequent solitary dinners in junior high school may set the stage for later elevations in picky eating, underscoring the preventive value of shared family meals before early adolescence.