How food portion size affects customer's decision while paying the bill

A new study has revealed that descriptions of portion size impacts how much we eat and how much we're willing to pay for our food.

The study by Cornell University researchers shows that consumers use such labels to dictate how much food they think is a "normal" portion, and then adjust their intake accordingly.

"People are willing to pay more for a portion that sounds larger, but they also are apt to eat more of an enormous portion if they believe it is 'regular' to do so," David R. Just, associate professor at Cornell's Dyson School of Applied Economics, said.

In their study, Just and Brian Wansink, professor of marketing at Cornell served study participants either one or two cups of spaghetti.

For some participants, the small and large portions were labeled "half-size" and "regular," respectively, giving the impression that the larger two-cup portion was the norm.

For other participants, the same portions were labeled "regular" and "double-size" - implying that the smaller one-cup portion was the norm.

"These varying concepts of 'regular' portions made all the difference in how much people would spend and subsequently eat," Just said.

"Participants ate much more when their portion was labeled 'regular' than when it was labeled 'double-size.' In fact, participants who thought their portion was 'double-size' left 10 times the food on their plate," he said.

Exploring how portion labels impact the willingness of patrons to pay, the researchers let participants bid on each portion.

When the portion was labeled "half-size," participants were willing to pay only half when the same portion was labeled "regular." The labels, rather than the visual appearance of each serving, acted as indicators.

"The huge impact of size labels suggests that both consumers and producers could benefit from standardization of food size-labeling," Wansink said.

The study is published online in the journal Health Economics.