Food and drink ‘sizes’ affect how much we buy and eat, finds study

By Nathan Gray

- Last updated on GMT

Related tags Food

Food and drink ‘sizes’ affect how much we buy and eat, finds study
The use of ‘normative’ size labels by food manufacturers plays a key role in how consumers buy and consume foods, according to new research. 

The study, published in Health Economics​, examined consumers’ willingness to pay for - and consumption of – foods of the same size that were labelled with different portion size wordings – finding that the wording used on a label has an influence on consumer purchase, consumption and even feelings of fullness.

Led by Dr David Just and Professor Brian Wansink from Cornell University, USA, the new study finds that consumers respond to these labels independently of the actual size of the products.

“Firms often use normative-size labels to describe their product options,” ​the authors noted. “This is particularly true among food manufacturers, retailers, and restaurants where normative labels describe bags of chips, servings of pasta, containers of French fries, size of salads, drink offerings, or nearly anything else that comes in multiple sizes.”

Just and Wansink suggested that such normative labels – like ‘regular’ or ‘large’ - inform consumers about how much food is offered “relative to some hypothetical normal, or regular, amount.”

“Controlling for size, our work finds that consumers are willing to pay more for portions that sound larger,”​ they concluded.

“Interestingly, size labels not only influenced the purchase of items, but also the amount individuals decide to consume once they have obtained the items.”

Study details

Just and Wansink split participants in to two groups, which then received the same meal options with different size labels. The team served two different portion sizes of lunch items - including spaghetti and salad – that were either small (one cup) or large (two cups).

The twist was in the labelling, though – for one group the small and large portions were labelled ‘half-size’ and ‘regular’ respectively, giving the impression that the large two-cup portion was normal. For the others, however, the same portions were labelled ‘regular’ and ‘double-size’—indicating that the smaller one cup portion was normal.

“These varying concepts of ‘regular’ portions made all the difference in how much people would spend and subsequently eat,”​ said Just. “Participants ate much more when their portion was labelled ‘regular’ than when it was labelled ‘double-size.’ In fact, participants who thought their portion was ‘double-size’ left 10 times the food on their plate.”

The researchers also explored how portion labels impacted the willingness of patrons to pay, by letting participants bid on each portion. They found that when the portion was labelled ‘half-size,’ participants were willing to pay substantially less than when the same portion was labelled ‘regular.’

“The huge impact of size labels suggests that both consumers and producers could benefit from ​standardisation of food size-labelling,” said Wansink.

“Clearly defining the actual amount of food in a ‘small’ or a ‘large’ would inform customers of just how much food they are ordering every time they ask for a certain size,”​ he said.

Source: Health Economics
Published online ahead of print, doi: 10.1002/hec.2949
Authors: David R. Just, Brian Wansink

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