Small, regular or large? The effect of size options on online food choices

The aim of the present study was to examine the effect of verbal size descriptors on portion size selections. Specifically, we investigated a range of size options within an online ordering setting. A sample of 216 female Flinders University students were asked to select a side dish, drink, and dessert from one of three online menus with varying portion size options: (1) small, regular, and large (SRL), (2) regular, large, and extra-large (RLXL), or (3) small, regular, large, and extra-large (SRLXL). Participants also completed a measure of dietary restraint. Across conditions, participants most frequently selected the ‘regular’ size for sides and drinks; however, for desserts a small size was equally preferred. In contrast to the concept of extremeness aversion, incorporating a small (S) or extra-large (XL) option into the choice-set did not significantly increase or decrease large size choices, respectively. However, dietary restraint moderated the effect of size option condition on portion selection for side-dish selections (but not for drinks and desserts), such that when an XL size was available, unrestrained eaters were relatively more likely than restrained eaters to pick a large or XL side dish. The findings support an overall preference for a normative sounding portion size. Accordingly, one useful strategy would be to reduce the size of regular serving portions to reflect an amount closer to current health guidelines.