Construction and Validation of a Culturally Adapted Eating Behaviour Assessment Tool for Nigerian Adults: A Mixed-Methods Psychometric Study

Eating behaviour measurement instruments developed in Western contexts cannot be uncritically applied to Nigerian adult populations characterised by distinct food cultures, communal eating norms, religious dietary practices, and socioeconomic food access constraints. The absence of a validated, culturally adapted eating behaviour assessment tool constitutes a fundamental methodological gap in nutrition research and dietary intervention design across Nigeria. This thesis describes the systematic development and psychometric validation of the Nigerian Adult Eating Behaviour Questionnaire through a rigorous mixed-methods research programme. Phase one comprised formative research including qualitative item generation through twenty focus group discussions across all six geopolitical zones and three expert consultation rounds for content validation. Phase two conducted cognitive interviewing with forty adults to assess item comprehension across literacy levels. Phase three administered the preliminary instrument to 840 adults across six states for factorial validity analysis using exploratory and confirmatory factor analysis, internal consistency assessment, and test-retest reliability over six weeks. Phase four examined criterion validity through comparison with validated biomarkers of dietary quality including serum carotenoids and omega-3 fatty acid indices. The final instrument comprises sixty-one items across eight theoretically coherent subscales addressing emotional eating, restrained eating, social eating norms, food neophobia, religious dietary compliance, convenience eating, budget-constrained food choice, and nutrition knowledge application. Psychometric properties were satisfactory across all reliability and validity parameters. Keywords: eating behaviour, psychometric validation, dietary assessment tool, cultural adaptation, Nigeria.