Exploring the pathways linking psychiatric symptom severity to diet quality: The role of dietary self-efficacy

Individuals with mental disorders have a higher risk for metabolic diseases such as adipositas and diabetes, mainly caused by unhealthy lifestyle factors such as unhealthy eating patterns. However, to date, no study has examined the role of dietary self-efficacy in the context of unhealthy eating behavior observed in psychiatric patients. The aim of the study was to (1) test whether dietary self-efficacy mediates the relationship between psychiatric symptom severity and diet quality in psychiatric patients, and (2) examine the association between diet-related self-efficacy and psychiatric symptoms. In a cross-sectional study, 405 psychiatric patients and 155 healthy controls (clinical staff members), aged between 18 and 66 years, participated in an anonymously conducted online questionnaire assessing diet quality, dietary self-efficacy, symptom severity, sociodemographic and control variables. Correlations and a mediation analysis were performed. Psychiatric patients reported significantly lower diet-related self-efficacy compared to healthy controls (p <.001). In both groups, diet-related self-efficacy was positively correlated with more favorable dietary behavior (p<.001). The mediation analysis showed a partial mediation of diet-related self-efficacy on the link between psychiatric symptom severity and diet quality (b = -0.87, 95% CI -1.34, -0.48). This study identifies diet-related self-efficacy as a relevant psychological factor in understanding the poorer diet quality observed in psychiatric patients. Lower dietary self-efficacy partially explains why patients struggle to translate knowledge and motivation into healthy dietary behavior and offers starting points for interventions.