How does food-cue exposure lead to larger meal sizes?

Exposure to the sight and smell of food influences our momentary desire to consume it. This study explored the process by which cue exposure promotes greater consumption of food. Three hypotheses were explored, cue exposure: (i) increases the planned consumption of food; (ii) increases tolerance of larger portion sizes; (iii) arrests the development of satiety. Female participants (n 50) were each tested in two conditions. In a 'cue condition' they were exposed to the sight and smell of pizza for 60 s. Before and after this period they provided information about prospective and maximum tolerated portion sizes and their desire to eat pizza and other non-cued foods. Participants then consumed a fixed portion of pizza, rated their hunger and were finally offered ad libitum access to pizza. In the 'no-cue condition', cue exposure was replaced with a cognitive task. Cueing had little effect on tolerance of larger portion sizes or on hunger after consuming the fixed portion. Instead, it increased prospective pizza portion size and subsequent intake of pizza. Together, these results suggest that cueing increases the amount of food that people actively plan to eat. This plan is then executed, leading to greater intake. Pizza cueing also increased prospective portion size of other foods. Thus, contrary to previous reports, effects of exposure may generalize to other foods. Finally, we found evidence that restrained eaters are less 'cue reactive' than unrestrained eaters. In future, our approach might be adapted to consider whether heightened 'cue reactivity' represents a risk factor for obesity.