Why wanting sustainable food is not enough: the habit barrier to green eating

Purpose This study addresses the persistent intention–behaviour gap in sustainable food consumption by re-specifying intention not as a proximate behavioural driver but as an upstream commitment whose enactment is contingent on execution-stage control. Design/methodology/approach Drawing on the Theory of Planned Behaviour integrated with habit psychology, the study models sustainable food consumption as a habit-conditioned execution process. Survey data from 463 Vietnamese consumers were analysed using PLS-SEM with formative higher-order constructs, mediation, moderation and conditional indirect effects. Findings Attitude, subjective norms and perceived behavioural control strongly predict purchase intention, yet intention exhibits only a weak direct effect on consumption behaviour. Habit strength emerges as the dominant execution-stage mechanism, significantly mediating and suppressing intention enactment. Consumer innovativeness weakens habitual dominance and amplifies the indirect effect of intention on behaviour, revealing systematic heterogeneity in executional permeability. Originality/value The study advances sustainable consumption theory by resolving the intention–behaviour gap as an execution-stage control problem rather than a motivational deficit. It reconceptualises habit as a mediating mechanism, introduces consumer innovativeness as a boundary condition on routine dominance and demonstrates configurational rather than additive behavioural causality.