There’s a new study out about calorie labeling and it comes to some interesting conclusions. It’s from the Rudd Center at Yale, authored by Christina Roberto, Peter D. Larsen, Henry Agnew, Jenny Baik, and Kelly D. Brownell. Here’s the basic description of the methodology and conclusion from the Rudd Center’s release:
The researchers studied 303 adults in New Haven, Connecticut, dividing them into three groups – the first saw a menu with no calorie labels, the second saw a menu with calorie labels, and the third saw a menu with calorie labels plus information on the recommended daily caloric intake for an average adult.
Participants in the two groups who saw calorie labels ate 14 percent fewer calories than the group whose participants did not see calorie labels. Furthermore, when after-dinner eating was factored in, people in the group who saw menu labels and recommended calorie guidelines consumed an average of 250 fewer calories than people in the other groups.
Unsurprisingly this result is being pitched as evidence in favor of mandatory calorie labeling and the headline used by credulous news sources like USA Today is quite a bit different from my own. Digging a bit deeper into the actual study [pdf] complicates the picture.
To its credit, the study addresses one of the questions ignored by much of the previous research: The possibility that people who are prompted to order lighter meals because they see calorie information will compensate by eating more food at other times. This study attempts to account for that by doing follow-up interviews with participants about what they consumed for the rest of the day. And this is where things get interesting:
Most striking was the impact of adding daily caloric requirement information to the menu. It was surprising how much participants in the calorie labels condition ate in the evening hours following the meal; when calories consumed in this condition during and after the study meal were combined, there was no advantage for calorie labeling only over no labeling. The advantage occurred when the menu included both calorie labels and a prominently displayed notice stating the average person should consume approximately 2000 calories per day. Total caloric intake for the combination of the study meal and food consumed later was 1630 calories, 1625 calories, and 1380 calories for the no calorie labels, calorie labels only, and calorie labels plus information conditions, respectively.
Emphasis mine. In other words, this study supports the arguments made by critics of mandatory labeling by finding that labeling alone doesn’t lead to reduced total consumption. Of course, that result is never mentioned in the press release.
There are other limitations to the study, perhaps most substantially the fact that it took place in an environment far removed from the atmosphere of a restaurant:
When participants arrived at 5:30 pm on the first day, they had been instructed to abstain from eating after 2:30 pm to standardize hunger levels. The experiment took place in a university classroom in a building not affiliated with eating research. Participants sat behind dividers so they could not see others’ meal choices; 2 to 14 individuals participated per study session.
It’s difficult to imagine anyone finding this environment conducive to having a pleasant meal. I have to wonder if outside a lab, when trying to enjoy themselves, participants would be more likely to indulge despite the calorie recommendation.
Regardless of that, this study suggests that calorie labeling alone won’t be sufficient to change diets. Thus we come to the next step:
The findings support the proposal that chain restaurants should be required to post calorie labels on restaurant menus; however, they suggest that to maximize the effectiveness of this policy, menu items should also include a label informing individuals of the daily caloric requirements for an average adult.
As Jacob Sullum wrote of mandated calorie postings last year, “There’s a difference between informing people and nagging them.” If health researchers get their way that difference is about to get even smaller.
Previously: For more on the question of whether nutritional information should be prominently posted or merely made available, see this post from July.