Gratitude for food is a concept associated with various aspects of healthy and sustainable diet and originates from Buddhism and Shintoism in Japan. Against this background, a scale specifically targeting adults is essential for boosting studies concerning gratitude for food. This study aimed to adapt the Gratitude for Food Scale (GFS), originally developed for Japanese children, to Japanese adults and to examine the reliability and validity of GFS for adults (GFS-A). This cross-sectional study used baseline and one-week follow-up data from a longitudinal survey. The analysis included 1800 Japanese adults at baseline and 1380 at the one-week follow-up based on completion of self-administered questionnaires in February 2023. Construct validity was confirmed using exploratory and confirmatory factor analyses. Further, Spearman's and intraclass correlation coefficients and Cronbach's alpha were calculated to confirm criterion validity and reliability (test-retest and internal consistency). Participants' mean (SD) age was 40.2 (11.2) years (women: n = 900, 50.0%) at baseline. The analysis revealed a one-factor structure comprising five items with good model fit. Criterion validity was confirmed by the correlation coefficients between the total GFS score and the gratitude questionnaire and the sub-score of awareness and appreciation for food, which represents a subscale of the expanded mindful eating scale. Moreover, test-retest reliability and internal consistency were confirmed. From this study's results, we can see that the developed GFS-A is an appropriate scale with good reliability and validity for measuring Japanese adults' gratitude for food.
Keywords: Japan; gratitude for food; mindful eating; scale development and validation.