Consumer research on healthy food choices often suffers from context effects and low predictive validity. Adopting a social cognition perspective, the paper proposes that consumers hold elaborate belief systems about food and health issues, but that these are only selectively accessed in different situations. Three studies are reported. In Study 1, 525 consumers answered a belief questionnaire. Structural equation modelling results demonstrate that health beliefs, when made accessible, form an interconnected system that can motivate successful self-regulation of healthy eating behaviour. Through a different route, however, the system can also motivate the use of judgemental heuristics of dubious value, enabling dissonance reduction without leading to dietary change. In Study 2, 185 consumers participated in a preference test. Experimental manipulations were used to activate a judgmental heuristic, resulting in systematic assimilation effects towards the anchors set by the judgmental heuristic. In Study 3, 10 consumers participated in a diary study where the instructions contained no hint towards health issues. Of the 286 entries in the thought protocols, only a single one referred to health as a motivating factor. Situational factors dominated consumers' food choice considerations, often in patterns developing coherence over time. It is concluded that consumers hold elaborate health belief systems, but that a lack of situational accessibility generally prevents them from gaining influence on actual behaviour.