Results of the present study showed that providing calorie information at the point-of-purchase on a fast food restaurant menu had little effect on food selection and consumption among a sample of adolescents and adults who eat regularly at fast food restaurants. These results contribute to a limited literature on point-of-purchase calorie labeling. To date, seven studies have examined the influence of providing calorie composition information at the point-of-purchase for most food items available in a cafeteria [14, 15, 17, 18, 37] or restaurant [24, 26] setting. Among these studies, one found no evidence of an effect of calorie labeling on food choices . In contrast, six of the seven studies found some evidence in support of the hypothesis that calorie information may positively influence food choices [14, 15, 24, 17, 26], however, results from most of these studies were weak or inconsistent. For example, Conklin et al. found that only 18% of college freshman living on a campus where point-of-purchase nutrition information was available in the dining commons agreed that the available information affected their choice of food .
A host of factors may explain the weak and inconsistent results in the literature. Firstly, the calorie labeling formats utilized varied across studies. For example, in one study 5 cm by 5 cm cards with calories in red ink were placed as close as possible to food items in a hospital cafeteria . In contrast, in another cafeteria study calorie information for all menu items was presented on two large posters at the cafeteria entrances, with leaflets distributed to patrons to encourage use of this information . Also, in three studies calorie information was provided along with other nutrient composition information such as saturated fat and fiber [14, 24, 37]. In the present study, calorie information alone was provided on a restaurant menu in a column between the food item name and price. To draw attention to it, the column was highlighted in bright yellow. Nonetheless, only slightly more than one-half of those who ordered from a menu with calories listed reported noticing this information. The calorie content of meals selected by those who noticed the information compared to those who did not were similar, suggesting our null results are not solely due to the failure of some to notice the calorie information.
The designs of studies conducted to date have varied greatly, with all having limitations. Most notably, four studies measured behavioral intentions [14, 24, 26, 37] rather than actual food choices. Consequently, social desirably bias in reporting is a significant concern in these studies. Other major weaknesses include use of quasi-experimental designs [15, 17, 18] where factors other than the experimental conditions being tested may have differed across test periods due to lack of randomization. The present study is the first to measure actual food choices within an experimental design where participants were randomly assigned to experimental condition. However, it has methodological weaknesses. Participants were exposed to the calorie information on only one occasion. This is a critical shortcoming if repeated exposure to calorie information is required before awareness or behavior change may be expected.
A final issue is that the weak and inconsistent results across studies may reflect heterogeneity in response to calorie labeling, with certain population subgroups more apt to utilize calorie information when it is provided. For example, a number of studies have found that females are more likely than males to use nutrition information on packaged food products [40–45]. Consequently, it is perhaps not surprising that Milich et al found calorie labeling to effect cafeteria food choices in a sample of female hospital employees , whereas Mayer et al. found no significant effect of calorie labeling on cafeteria food choices in a study involving male and females employees of a Fortune 500 company . The results of the present study are consistent with the notion that certain population subgroups may be more likely to use calorie information when it is provided. In the present study males appeared to use the calorie information to choose a higher calorie meal. This finding could be an artifact of multiple comparisons, as a significant number of subgroup analyses were conducted. Conversely, this result could reflect a desire among males for an energy dense meal. To our knowledge, only one other study  has reported findings suggesting an unintended consequence of calorie labeling. Yamamoto et al. conducted a study in which adolescents were asked to order meals from three different restaurant menus that did not contain nutrition information, and then reorder their meals after being shown a version of the menus that included calorie and fat content information for menu items. Approximately 17% of meal orders were changed in response to the calorie and fat information. Among the meals that were modified, 20.4% were modified in a way that resulted in a higher calorie content meal.
In the present study the elimination of value size pricing was found to have little influence on food selection or consumption. This finding is somewhat surprising given that a number of studies have documented that price changes may influence food choices [32, 46–48]. The price shifts we evaluated tended to be smaller in magnitude compared to those evaluated in previous studies, which could explain why our results conflict with previous findings. It is also possible that the null results are due to the study design which provided only one exposure to the price modification. When queried regarding whether they had noticed the modified pricing structure, less than one-fifth responded affirmatively. Since most fast food restaurant chains utilize a value size price structure, it is possible that study participants generally assumed the larger sized items were the better value without considering the prices listed on the menu. In consideration of this potential methodological issue, future studies designed to evaluate value size pricing should ensure repeated exposure to price modification.
The present study has a number of strengths. The study measured actual food choices rather than behavioral intent. Consequently, social desirability bias in reporting is likely less of a concern and internal validity is probably better than studies that only measured behavioral intent. A randomized design was employed ensuring that potential confounding factors, such as age and sex were equally distributed across experimental conditions. Another strength of the present study is that participants were a community sample of adolescents and adults who ate regularly at fast food restaurants. Consequently, the external validity of results may be stronger than many previous studies.
Limitations of the present study include that participants were exposed to the experimental condition only once. As mentioned earlier, this is problematic as it is possible that repeated exposure to calorie information and standardized pricing may be required before behavior is impacted. Although participants were blinded to the true intent of the study, and the ordering and dining procedure was set-up to be as naturalistic as possible, subject reactivity remains a concern. Of particular concern is the possibility that the participation incentive undermined price sensitivity.
It is important to note that most of the study limitations just described could have been avoided if the study had been conducted in fast food restaurants where menu boards and prices could be manipulated for prolonged periods of time. Unfortunately we were not able to find any fast food restaurants willing to collaborate with us, and thus we were not able to implement a more rigorously designed study.