Whether or not labeling foods with their calorie content would make a difference in people's choices has been a bone of contention in the nutrition world. Some research has demonstrated a positive effect, while other studies have not.
Also, much of the research has been carried out in pretty unnatural situations. A new study, just reported in the Journal of Public Policy & Marketing used an approach that allowed participants to make food choices in a more natural, or field setting.
Dr. Eric M. VanEpps from the University of Pennsylvania teamed with colleagues from Carnegie Mellon University to investigate the effect of 2 types of calorie labels on choices of lunch foods. Participants in the study were employees of Humana — they were told that they were testing a new online system for ordering food. Participation was voluntary, and those who joined the study received small remunerations ($3-$5 ) in the form of lunch discounts as well as for completing entry and exit surveys.
The main purpose of the study was to determine if two types of calorie labels on lunch foods would have an impact of diners' choices. One group of participants saw a numerical listing of the number of calories in a food, the other saw a so-called stoplight system, in which entrees, snacks and drinks received either a green (for okay — under 400 calories), yellow (for caution — under 550 calories) or a red (stop — over 550 calories) light symbol. A third group had both a numerical listing as well as a stoplight symbol. A control group had no information on calorie content.
The first part of the study ran for 4 weeks, and then about 1/3 of the subjects elected to continue for another 2 weeks.
Men in the study ordered significantly fewer calories when their foods were labeled, while labeling seemed to affect women's ordering only marginally. Compared to the no-label control group, obese participants ordered significantly fewer calories when they saw either type of label, as well as when both labels were presented. Another finding was that people with lower numeric literacy (which was tested for) were affected by the traffic light labels more than by either the numeric labels or the combination labels, while those with high numeric literacy responded to both the numeric and combination labels to a greater extent.
The authors noted that calorie reduction in this study resulted from different food choices, rather than from smaller portion sizes or selecting fewer items. The results of the study indicate that, depending on the population studied, calorie labeling by either a numeric or traffic light system can have an impact on food choices. It's important to note, however, that the participants in this study were mostly white and more than half were female, and their education level was relatively high, suggesting that the results may not be broadly applicable. However, the results do support the concept of the importance of giving consumers adequate information about calorie content of food choices to encourage lower consumption levels.