Last year, the Food and Drug Administration announced it would be overhauling its Nutrition Facts label for the first time in more than 20 years. Among proposed changes to the chart, which is found on most food packaging, is a more realistic assessment of serving size, which reflects the amount of the product people actually eat at one sitting.
This shift has been widely praised by public health advocates, who consider many of the current serving sizes (one-half cup of ice cream?) unrealistically small. This way, they argue, people will have a better sense of the number of calories and grams of fat they are actually consuming.
But newly published research suggests there's just one small problem with this initiative: It appears to prompt people to eat even more.
"We found that people misinterpret serving size information, with the vast majority of consumers incorrectly believing that the serving size refers to how much can/should be consumed," a research team led by Steven Dallas of New York University writes in the journal Appetite.
Those who viewed the proposed label indicated they would eat significantly more cookies than those who saw the traditional label.
"Second, we found that the increased serving sizes on the proposed Nutrition Facts label can lead consumers to serve and purchase more food for themselves and others when they use this information as a resource."
In other words, while the FDA sees the larger serving sizes as a concession to reality, the public—to the extent it pays attention to official labels—views them more as a norm that serves as a reasonable baseline for their own behavior. Hey, if this is what the federal government considers a "serving," who are we to argue? Let's dig in!
Dallas, along with two colleagues from Duke University, provides evidence of how people actually respond to such labels in a series of four studies. In the first, 101 people recruited online were presented with an example of either the current Nutrition Facts label or the proposed revision. They were then asked; "What do you think the 'serving size' on the Nutrition Facts panel refers to?"
Among those who viewed the current label, "82.4 percent incorrectly responded that the serving size refers to the amount of product that people can or should consume in one sitting as part of a healthy, well-balanced diet." A similar proportion—78 percent—gave that same response after seeing the proposed new label.
But does this misunderstanding impact actual behavior? Follow-up studies strongly suggest so. In one, featuring 51 adults, participants viewed either the current or proposed Nutrition Facts label for mini chocolate chip cookies, and were then offered samples of the sweet treat. They were specifically asked how many they would expect to eat if they were serving themselves a snack.
Those who viewed the proposed label, with its larger serving size (six cookies rather than three), indicated they would eat significantly more cookies than those who saw the traditional label.
In another study, 61 undergraduates were presented with family-sized lasagnas (so there could be no doubt about their actual size). Again, half read the traditional label (which listed six servings per container), while the others viewed the proposed substitute (which reduced the number of servings to three).
Participants were then asked how many such lasagnas they would buy if they were hosting a dinner party for 20. Those exposed to the current label indicated they'd purchase an average of five; for those who saw the new label, that number increased to 7.17.
"Increasing serving sizes on the proposed Nutrition Facts label may have several negative, unintended consequences," Dallas and his colleagues conclude. "The proposed Nutrition Facts label is intended to help consumers make healthier consumption decisions, but the current research suggests that it may backfire, leading consumers to serve more to themselves and others."
How can this be fixed? The researchers have some ideas, including adding a definition of "serving size" to the label, pointing out that it "does not refer to how much of the product can be healthily consumed in one setting."
But they concede this may not be effective, since "descriptive norms can have a powerful influence on people's behavior." If a number gives us license to indulge, it's easy to ignore the printed warning. So stronger language may be needed—or, better yet, an effective campaign of nutrition education that teaches people the basics of healthy eating.
One thing seems clear: If the government's goal is to reduce obesity, simply increasing the "serving size" on the label could easily backfire. And that would give both policymakers and indulgent consumers a bad case of indigestion.
Findings is a daily column by Pacific Standard staff writer Tom Jacobs, who scours the psychological-research journals to discover new insights into human behavior, ranging from the origins of our political beliefs to the cultivation of creativity.