Portion Size Me: Plate-Size Induced Consumption Norms and Win-Win Solutions for Reducing Food Intake and Waste

• Published in: Journal of experimental psychology. Applied 2013-12, Vol.19 (4), p.320-332
• Main Authors: Wansink, Brian, van Ittersum, Koert
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Biological and medical sciences; Cooking and Eating Utensils; Eating - psychology; Female; Food; Food Intake; Fundamental and applied biological sciences. Psychology; Human; Humans; Illusions (Perception); Male; Middle Aged; Perception; Portion Size - psychology; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Restaurants; Size Perception; Vision; Visual Perception; Young Adult
• ISSN: 1076-898X; 1939-2192
• DOI: 10.1037/a0035053

Research on the self-serving of food has empirically ignored the role that visual consumption norms play in determining how much food we serve on different sized dinnerware. We contend that dinnerware provides a visual anchor of an appropriate fill-level, which in turn, serves as a consumption norm (Study 1). The trouble with these dinnerware-suggested consumption norms is that they vary directly with dinnerware size-Study 2 shows Chinese buffet diners with large plates served 52% more, ate 45% more, and wasted 135% more food than those with smaller plates. Moreover, education does not appear effective in reducing such biases. Even a 60-min, interactive, multimedia warning on the dangers of using large plates had seemingly no impact on 209 health conference attendees, who subsequently served nearly twice as much food when given a large buffet plate 2 hr later (Study 3). These findings suggest that people may have a visual plate-fill level-perhaps 70% full-that they anchor on when determining the appropriate consumption norm and serving themselves. Study 4 suggests that the Delboeuf illusion offers an explanation why people do not fully adjust away from this fill-level anchor and continue to be biased across a large range of dishware sizes. These findings have surprisingly wide-ranging win-win implications for the welfare of consumers as well as for food service managers, restaurateurs, packaged goods managers, and public policy officials.