The present study was designed to see whether variables from the transtheoretical model could account for changes in behavior, as opposed to changes of stage. A broadly representative sample (N = 356) completed measures of transtheoretical model constructs and dietary intake at baseline; dietary intake was measured at follow-up. One of the processes of change, self-reevaluation, predicted changes in behavior and significantly mediated the effect of past behavior on future behavior. It is rare that social cognitive variables mediate the effects of past behavior on future behavior meaning that self-reevaluation provides a potential avenue for promoting dietary change.