Pictures of big portions lead to overeating, study warns

The study makes a particular example out of frosted cake – an image normally featured on cake-mix boxes. Consumers are often unaware that frosting is not included in the serving size recommendation described on the nutrition label.

"Undoubtedly, companies don't intend to deceive us when they include frosting in cake box depictions, but these seemingly small elements of packaging can have a huge impact,"​ said co-author Brian Wansink.

Ineffective nutrition labels ​

Nutritional labels are designed to promote healthy food choices and serving sizes. However, 70% of consumers routinely ignore these labels​​, causing researchers to question their effectiveness.

This is particularly relevant for serving size. Large serving sizes play a large role in obesity​,​ consumers still tend to ignore serving size information and serve larger portions than recommended​.​

Studies have already shown that packaging often exaggerates recommended serving size. When compared with the recommended serving size, the majority of ice cream containers display pictures of ice cream that are, on average, 130% more.​​

Cornell Food and Brand Lab researchers conducted a survey featuring 72 undergraduates and 44 females in the food service industry. They found that these overly caloric depictions caused both groups to overestimate serving size.

The latter group overestimated by 122 calories. However, when the phrase "frosting not included on the nutritional labelling,"​ appeared on the box, estimation of an appropriate serving size was significantly reduced.

“The study is consistent with our hypothesis that showing supplementary products not listed on the nutritional labelling causes an increase in intended serving size,”​ the author’s noted pointing to earlier findings that demonstrated the impact food packaging had on serving size.​​

Industry relevance​

While these results have important implications for policy officials they also have implications for food manufacturers that wish to promote healthy serving sizes.

Recent efforts to promote appropriate serving sizes have focused on creating multipacks that contain premium-priced individualised portions​.​ However, the increased cost of producing this packaging is often passed on to the consumer.

The researchers said that a more cost-effective way to promote healthy serving sizes was to explicitly state what was included in the nutritional information.

“Although this proposition is supported by the present results, future research is needed to better understand how visually appropriate serving size images (and messages) interact with other factors that are known to influence how much a person serves (e.g. convenience),”​ the study said.

Source: Public Health Nutrition​

Published online ahead of print, doi:10.1017/S1368980016000458​​

“Frosting on the cake: pictures on food packaging bias serving size.”​

Authors: John Brand, Brian Wansink, and Abby Cohen