Are we aware of the external factors that influence our food intake?

OBJECTIVES: This research examines the extent to which people accurately report some of the external influences on their food intake. DESIGN: In two studies, specific factors (the presence and behavior of others) were manipulated in order to influence the amount of food that individuals consumed. MAIN OUTCOME MEASURES: The main outcomes of interest were participants' spontaneously generated explanations for their food intake (Study 1; n = 122), and their ratings of the importance of several potential determinants of food intake (Study 2; n = 75). RESULTS: In Study 1, there was high concordance between the amounts eaten by members of a dyad, but very few participants indicated that they were influenced by their partner's behavior; they instead identified hunger and taste as the primary determinants of intake. Study 2 showed that participants' intake was strongly influenced by the behavior of others, but people rated taste and hunger as much more important influences on their intake. CONCLUSIONS: If external environmental factors influence people's food intake without their awareness or acknowledgment, then maintaining a healthy diet can be a challenge, with long-term consequences for health and well-being.