Adding more portion-size options to a menu: A means to nudge consumers to choose larger portions of healthy food items

We propose and find that the extremeness aversion bias when choosing portion-sizes is stronger for healthy food as compared to unhealthy food items. In two studies (and a follow-up) we find that adding an extra-large option to a standard menu of small, medium, and large portions increases the choice share of the larger portion-sizes; but more so for healthy food than for unhealthy food. Furthermore, we find evidence for the lay belief that larger portions of healthy food do not have incremental health costs. When health costs of the larger portions of healthy food were made salient by providing calorie information, the above effects disappeared. These findings show (1) a boundary condition to the extremeness aversion effect when choosing portion sizes, and (2) imply that this bias can act as a nudge to increase the consumption of healthy food.