Labelling influences perceptions of portion size

What’s the difference between regular and supersized? Just the label, according to US researchers. New research conducted by Dr David R Just and Dr Brian Wansink of the Cornell Food and Brand Lab suggests that portion labels impact our entire eating experience.

The researchers conducted a study in which participants were served two different portion sizes: either 1 cup (small) or 2 cups (large). The twist was in the labelling: for some participants, the small and large portions were labelled ‘half-size’ and ‘regular’ respectively, giving the impression that the 2-cup portion was the norm. For others, the same size portions were labelled ‘regular’ and ‘double-size’, suggesting that the smaller 1-cup portion was the norm.

The researchers found that these varying concepts of ‘regular’ portions made all the difference in how much people would spend and subsequently eat.

When served identical 2-cup portions of spaghetti, participants ate much more when it was labelled ‘regular’ than when it was labelled ‘double-size’. In fact, those who were told their portion was ‘double-size’ left 10 times as much food on their plates.

When it came to paying for food, the researchers found that people were only willing to pay half as much for a 1-cup portion labelled ‘half-size’ as they were for the same portion labelled ‘regular’.

Drs Just and Wansink said the study indicates the people primarily use labels alone to dictate how much food is a ‘normal’ portion, and then adjust their intake accordingly. The study also shows that people are not only willing to pay more for a portion that sounds larger, but they will also eat more of a large portion if they believe it is the standard size.

The researchers say that both consumers and producers could benefit from standardisation of food-size labelling; clearly defining the actual amount of food in a ‘small’ or ‘large’ portion would inform consumers about just how much food they are purchasing.

The full research paper, One man’s tall is another man’s small: how the framing of portion size influences food choice, was published in the journal Health Economics.