Size matters when ordering food online, says study

What effect does verbal size descriptors have on portion size selections when people order their meals online? Quite a lot—and some cues can prompt people to order a larger size—according to new research from Flinders University.

The availability of an XL option, rather than the number of available options, proved influential in determining a person's choice for a larger order—although surprising restraint was shown by diners who admitted they were following dietary regimes.

Study recipients were all female students, some following diets (restrained eaters) and some unrestrained. They were asked to select a side dish, drink, and dessert from one of three online menus with varying portion size options: SRL (small, regular and large), RLXL (regular, large, and extra-large) or SRLXL (small, regular, large, and extra-large).

Participants most frequently selected the "regular" size for sides and drinks, or a small size for desserts. However, when an XL size was available, the "unrestrained" eaters were more likely than "restrained" eaters to select a Large or XL side dish.

Professor Eva Kemps, from the College of Education, Psychology and Social Work at Flinders University, says this suggests that when an XL size option is available, people adjust their ordering choices.

The research paper—"Small, regular or large? The effect of size options on online food choices," by Eilish Mckay, Eva Kemps, Ivanka Prichard and Marika Tiggemann—has been published in Food Quality and Preference.

"In contrast to our prediction, incorporating a larger portion size option (XL) did not significantly increase large size choices, and conversely including a small size option (S) did not significantly decrease large size preferences," says Professor Kemps.

"One possible explanation for this discrepancy is that when consumers have access to a labeling system that provides a normal-sounding size option as a reference—such as a 'regular' serve—their aversion to extreme size options has a much lesser effect.

The findings support an overall preference for a normal-sounding portion size. Professor Kemps says it would therefore be a useful strategy to reduce excessive calorie intake by also reducing the size of regular serving portions, which would reflect an amount closer to current health guidelines.

"These findings suggest that people may perceive a 'normal' portion size based on the reference point option (calling it 'regular') rather than the middle available size option and thus select accordingly," she says.

"Why is this important? Because poor diet and increased food consumption have led to an escalation in lifestyle-related diseases such as cardiovascular disease, type 2 diabetes and high blood pressure, which have become an increasing global public health concern."

Rather than consider such measures as introducing food taxes on unhealthy foods, the researchers now want to investigate whether more implicit strategies might be used to promote better food choices, especially to reduce portion sizes of unhealthier foods.