The 'variety effect' is anticipated in meal planning.

The 'variety effect' describes the greater consumption that is observed when multiple foods with different sensory characteristics are presented either simultaneously or sequentially. Variety increases the amount of food consumed in test of ad libitum intake. However, outside the laboratory, meals are often planned in advance and then consumed in their entirety. We sought to explore the extent to which the variety effect is anticipated in this pre-meal planning. Participants were shown two food images, each representing a first or a second course of a hypothetical meal. The two courses were either, (i) exactly the same food, (ii) different foods from the same sensory category (sweet or savoury), or (iii) different foods from a different sensory category. In Study 1 (N=30) these courses comprised typical 'main meal' foods and in Study 2 (N=30) they comprised snack foods. For each pair of images, participants rated their expected liking of the second course and selected ideal portion sizes, both for the second course and the first and second course, combined. In both studies, as the difference between the courses (from (i) same to (ii) similar to (iii) different) increased, the second course was selected in a larger portion and it was rated as more pleasant. To our knowledge, these are the first studies to show that the variety effect is evident in the energy content of self-selected meals. This work shows that effects of variety are learned and anticipated. This extends our characterisation beyond a passive process that develops towards the end of a meal.