NEW HAVEN, CONN. — A new study conducted by researchers from Yale University sheds new light on how calorie labels on restaurant menus may impact food choices and intake. The study, "Evaluating the Impact of Menu Labeling on Food Choices and Intake," appeared on-line Dec. 17 in the American Journal of Public Health.
As part of the study, the researchers randomly assigned 303 participants in the New Haven community ages 18 and older to either a menu without calorie labels, a menu with calorie labels, or a menu with calorie labels and a label stating the recommended daily caloric intake for an average adult.
Food for the study contained the same items from two restaurants — Au Bon Pain and a local, non-chain restaurant. Menu items included all salads, dressings, sandwiches, wraps and selected beverages and desserts from Au Bon Pain, as well as traditional fast food from the non-chain restaurant, including mozzarella sticks, french fries, pizza, hamburgers and cheesecake.
Calorie values for the non-chain restaurant were estimated by the researchers by weighing the items on an Ohaus digital scale and entering those weights into the Food Processor SQL calorie content database.
"Calorie information on restaurant menus reduced the total amount of calories people ordered and consumed for a meal, improved their ability to estimate calories consumed, and, perhaps most important, affected their eating later in the day," the researchers noted. "Participants of both calorie label conditions ordered significantly fewer calories than those in the no calorie labels condition. When the two calorie label conditions were combined, this group’s participants consumed 14% fewer calories than those in the no calorie labels condition. On average, people in the calorie labels group and the calorie labels plus information group consumed 124 and 203 fewer calories, respectively, at the dinner meal than did those in the no calorie labels condition."
Interestingly, the researchers found that total calories consumed during and after the meal was 1,630 calories, 1,625 calories and 1,380 calories for the no calorie labels, calorie labels only and calorie labels plus information conditions, respectively. According to the researchers, the data suggests participants in the calorie label only group felt hungrier later in the day or simply believed they had greater allowance to eat more, while participants given additional information conditions appeared to eliminate excess eating later.
"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, menus should also include a label informing individuals of the daily caloric requirements for an average adult," the researchers said.
The researchers acknowledged that no price information appeared on the menus, which limited their ability to compare how price interacts with menu labels. In addition, the participants were a "convenience sample," and were not randomly sampled a nationally representative group, which may have introduced selection bias.