Nutritional Pearls: Don't Believe the Picture

Mary is a 21-year-old college student struggling to lose weight. Because of her busy schedule, she often relies on frozen and prepackaged meals for lunch and dinner.

When asked whether she reads the nutritional information, she replies, “No, I usually just choose the ones that look the healthiest on the front of the box.”

How do you advise your patient?
(Answer and discussion on next page)

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Answer: Reading the nutrition information carefully is the only way to know exactly what the food manufacturers are considering a serving.

A recent study looked at the effect of different labeled serving sizes on what people believed were reasonable serving sizes as well as how much of that food they believed they would eat.¹ While the respondents believed the foods labeled with larger serving sizes to be less healthy than the same food with a smaller serving size, they were basing that belief on reading the nutrition label the authors of the study provided.

The Research

Brian Wansink and his team at Cornell approached the issue from a slightly more real-world approach: looking at what is actually depicted on the front of the box.² Many packaged foods have pictures on the box that show more than just what is in the box: Cereal is shown with milk, or Hamburger Helper with ground beef. Wansink and his team chose to use cake mixes, which often show the finished cake with frosting (and plenty of it). Would people take that frosting into account when looking at the cake mix box and deciding on what they thought was a reasonable serving?
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The First Study

In the first of 4 studies, the authors calculated the number of calories in the slice of cake shown on 51 different boxes of cake mixes from 3 major brands (Duncan Hines, Betty Crocker, and Pillsbury). Assuming an 8-inch cake pan, they measured the angles of the wedge of cake shown on the box and were able to estimate the amount of cake shown. Similarly, they could also estimate the surface area of that wedge of cake covered in frosting, and assuming an average type and thickness of frosting, they could estimate the number of calories of frosting that was shown on the box.

It shouldn't surprise you that since the frosting wasn't included in the nutrition information on the boxes, the slices of cake displayed, including frosting, contained on average about 135% more calories than was listed in the nutrition facts for the cake alone. Duncan Hines was the worst culprit, with a piece of frosted cake on its packaging that contained more than twice as many calories as the recommended amount of cake alone.

The Second Study

In a second study, 45 undergraduates were shown 2 packages of cake mix and asked to estimate the number of calories of cake alone that would be a reasonable serving. Fifteen of the students were told that "the frosting shown on the front of the packaging is not shown on the nutritional labeling," while another 15 were not given that information about the frosting. The final 15 students were given the same boxes with the pictures altered to show pieces of cake without frosting and were asked to estimate the appropriate number of calories in a serving.

Those who were shown cake with frosting but were not told that the frosting was not included in the nutrition information estimated that an appropriate serving of cake would contain 80% more calories than those who knew that frosting was not included. Those who were shown pictures that did not include frosting estimated a serving size that was about the same as those who saw pictures with frosting but who were instructed that frosting wasn't included.

The Third and Fourth Study

The third and fourth studies the authors performed were essentially the same, differing only in the respondents: The first iteration was performed in undergraduates, while the second was in food service professionals, whom one would think would be more nutrition-facts savvy. Individuals were shown a box of cake mix whose picture included the frosting next to an actual cake (also with frosting) that had been precut into slices of varying sizes, from very small to very large. The participants were instructed to choose the slice of cake that represented the amount they would serve themselves. Some of the participants were told that the nutrition information on the cake mix box included the frosting, while others were not. Once again, those who were not explicitly told that frosting wasn't included in the nutrition information chose larger slices than those who knew the frosting wasn't included—and this was true for both food service professionals and undergraduates.

What’s the “Take-Home”?

It's clear that the picture on the box can influence your perception of a normal or reasonable portion and trick you into thinking that extras like syrup and butter (as for pancakes) are included in a product's nutrition information. Be a smart consumer and read the nutrition information carefully so that you know exactly what the food manufacturers are considering a serving: Is it really the same thing shown on the box?

References:
1. Hydock C, Wilson A, Easwar K. The effects of increased serving sizes on consumption. Appetite. 2016;101:71-79.
2. Brand J, Wansink B, Cohen A. Frosting on the cake: pictures on food packaging bias serving size. Public Health Nutr. 2016;19(12):2128-2134.