Objective: Increased levels of dietary restraint are associated with deficits on many cognitive tasks. Less is known about how individual differences in restraint influences complex cognition such as reasoning which is the focus of this research.

Design: Two experimental studies are reported. In study 1, participants (n = 158) completed a causal conditional reasoning task with statements about weight-related and general causal relationships. Study 2 replicated and extended study 1. Participants (n = 108) completed a causal conditional reasoning task focusing on behavioural causes of weight change or general statements.

Main outcome measure: Causal conditional reasoning task performance.

Results: In study 1, levels of dietary restraint were negatively associated with reasoning abilities for weight-related statements only. Study 2 replicated the negative association between dietary restraint and reasoning finding the effect in both weight-related, and general, causal judgements.

Conclusion: The novel findings show that individual differences in dietary restraint have a wider relationship with cognition than previously demonstrated. Results tentatively support theoretical explanations of a reduction in cognitive capacity, rather than differences in belief, explaining reasoning deficits. These findings open an interesting avenue for research and might have implications for effective decision making about personal health behaviours, such as food choice.