(PhysOrg.com) -- Consumers tend to overeat large sizes of food labeled as small and feel that they have not eaten too mucheven if they're aware of the actual portion size and nutrition content, says a University of Michigan researcher.
"Mislabeling larger items as being smaller allows consumers to guiltlessly consume more, what we refer to as 'guiltless gluttony,' and can impact both actual and perceived consumption," said Aradhna Krishna, the Dwight F. Benson Professor of Marketing at U-M's Ross School of Business. "This can result in unintended and uninformed overconsumption, which can clearly have dire consequences for health reasons."
In new research forthcoming in the Journal of Consumer Research, Krishna and colleague Nilufer Aydinoglu of Koc University in Istanbul found that size labels (small, medium, large, extra large, etc.) used by food companies can have a major impact on consumers' size judgments and purchase and consumption behaviors.
Prior research has shown that consumers have a difficult time estimating food volume through visual inspection or from a feeling of satiation (feeling full) or when verbally told the actual size of a food item.
"Even if benchmarks are provided within the verbal information, the lack of consistent portion sizes across food providers restricts their use and still makes size estimation difficult," Krishna said. "As such, size labels, such as small and large, may provide consumers with easy-to-interpret crutches for direction on size judgment and also on the appropriate amount to eat and drink."
Krishna and Aydinoglu conducted a series of five studies with more than 600 participants in the United States and Europe. Not only did they find that consumers perceive large sizes of food to be small or medium in size when they're labeled as suchand will, consequently, eat moretheir results also show that consumers are less likely to believe that a small-sized item labeled as medium or large, is, in fact, labeled correctly.
In other words, underestimations are more likely and increase in magnitude as the size of the meal increases, the researchers say. Underestimations of large meals, therefore, are bigger than the overestimations of small meals.
They say, however, that there are moderating influences on "guiltless gluttony." For example, those less prone to this effect are highly nutrition-minded consumers, as well as those that have the time and wherewithal to consider all information sources and who have a high regard for accuracy in their daily routines. Unfortunately, this is not often the case.
"It has been shown that consumers are not very motivated to be accurate in many routine behaviors entailing frequently purchased goods," Krishna said. "In the context of purchasing and consuming dozens of products each day, consumers may find it too time-consuming and unnecessary to estimate sizes of individual products accurately."
Instead, they tend to rely on labels.
"Our results show that the use of different size labels for the same product affect the amount people consume," Krishna said. "And consumers may not even be aware of the effect of the size label on their consumption.
"Such behavior is clearly ridden with significant health ramifications, and size labels could be contributing to the rampant obesity problems in the United States. Stricter size labeling laws and more vigilant monitoring of marketers' use of size labels may be needed, especially considering the limited cognitive resources available to consumers for routine food choice and consumption behavior during their everyday endeavors."
Explore further: Local homicide rate increases cause more elementary students to fail school