Effects of energy conditioning on food preferences and choice.

This study investigated the development of conditioned preferences for foods varying in energy content in human adults in a laboratory setting. In a within-subjects design, 44 participants consumed high and low energy yoghurt drinks (255 kcal and 57 kcal per 200 ml serving, respectively) first thing in the morning following 8 h of fasting, every day for two weeks, with 5 exposures to each yoghurt drink on alternate days. The high and low energy yoghurt drinks were paired with two coloured labels (blue or pink), with the pairings fully counter-balanced. Every day of the third (test) week, participants were given a free choice of either consuming the pink or the blue labelled yoghurt drink. Participants chose the high energy drink significantly more often over the low energy drink, suggesting a conditioned preference for a delayed (energy) reward. These findings provide further evidence for energy based learning in human adults. This study also provides a new approach to the conditioning paradigm (cueing energy via a coloured label instead of flavour) and includes a new and important measure in this research area (preference instead of liking).