Extending the Theory of Planned Behavior for Explaining Dietary Quality: The Role of Financial Scarcity and Food Insecurity Status

Objective: To examine whether an extended Theory of Planned Behavior (TPB) that included finance-related barriers better explained dietary quality.

Design: Cross-sectional survey.

Participants: One-thousand and thirty-three participants were included from a Dutch independent adult panel.

Main outcome: Dietary quality.

Analysis: Five TPB models were assessed: a traditional TPB, a TPB that included direct associations between attitude and subjective norm with dietary quality, a TPB that additionally included financial scarcity or food insecurity, and a TPB that additionally included financial scarcity and food insecurity simultaneously. Structural relationships among the constructs were tested to compare the explanatory power.

Results: The traditional TPB showed poorest fit (χ²/degrees of freedom = 11; comparative fit index = 0.75; root mean square error of approximation [95% confidence interval], 0.10 [0.091-0.12]; standardized root mean square residual = 0.049), the most extended TPB (including both financial scarcity and food insecurity) showed best fit (χ²/degrees of freedom = 3.3; comparative fit index = 0.95; root mean square error of approximation [95% confidence interval], 0.050 [0.035-0.065]; standardized root mean square residual = 0.018). All 5 structure models explained ∼42% to 43% of the variance in intention; however, the variance in dietary quality was better explained by the extended TPB models, including food insecurity and/or financial scarcity (∼22%) compared with the traditional TBP (∼7%), indicating that these models better explained differences in dietary quality.

Conclusions and implications: These findings highlight the importance of accounting for finance-related barriers to healthy eating like financial scarcity or food insecurity to better understand individual dietary behaviors in lower socioeconomic groups.