A Cognitive Study of Dietary Imbalance Behaviors in Chinese Multigenerational Households Based on the Information–Motivation–Behavioral Skills Model

Background/Objectives: Family dietary imbalance is an important source of the double burden of malnutrition, and dietary arrangements in multigenerational households are often deeply embedded in intergenerational caregiving relationships. However, the cognitive formation mechanism through which dietary caregiving behaviors driven by care and responsibility may instead lead to dietary imbalance still lacks systematic explanation. Therefore, this study aimed to examine the cognitive formation mechanism of dietary imbalance behaviors in Chinese multigenerational households. Methods: This study takes primary dietary caregivers in Chinese three-generation households as the research subjects. It integrates the false consensus effect, cognitive dissonance theory, and the information–motivation–behavioral skills (IMB) model. Based on 467 valid samples, the study conducts empirical analysis using partial least squares structural equation modeling (PLS-SEM) and importance-performance map analysis (IPMA). Results: The results show that caregivers’ subjective judgments about family members’ dietary needs based on their own experience trigger cognitive dissonance and further promote their re-examination of dietary risk information, caregiving responsibilities, and family normative expectations. Among these factors, caregiving responsibilities and subjective norms are key factors in improving dietary regulation self-efficacy, whereas the effect of risk information perception on self-efficacy is not significant. The IPMA results further show that self-efficacy is the most important factor driving the formation of behavioral intention to regulate healthy family diets. Conclusions: This study reveals the psychological mechanism through which dietary imbalance behavior in multigenerational households moves from subjective need judgment to the formation of future regulation intention. It extends the application of the IMB model in family caregiving contexts and provides a theoretical basis and practical implications for the formulation of family health promotion and dietary intervention strategies.