Calorie labelling has been implemented as a public health strategy to address obesity, but its mechanisms of action are not well understood. Drawing on expectancy-value models, this study explored whether calorie labelling influences the calorie content of items selected from a hypothetical coffee shop menu via changes in outcome expectancies and whether effects are moderated by food choice motives. Adults ( n = 577) were randomly assigned to view a menu with ( n = 290) or without ( n = 287) calorie information and select their preferred items(s). The primary outcome was total calories selected. Secondary outcomes were change in weight control, health, taste, value for money and fullness expectations for each menu item and participants’ motivation for weight control, health, price and sensory appeal. Exploratory outcomes included participants’ calorie estimates for each menu item. Labelling did not significantly reduce calories selected ( p = .18), though means were in the predicted direction (labelling M = 371, SD = 261; no labelling M = 392, SD = 249, 5% decrease). Labelling significantly increased health, weight control and value for money expectations of menu items but these changes did not influence calories selected. A sensitivity analysis suggested moderation by weight control motivation whereby labelling reduced calories selected among highly motivated participants, although this effect was not observed across other models. Labelling was associated with better calorie estimation accuracy. Findings suggest that while calorie labelling may influence beliefs and knowledge, its acute impact on population level behaviour may be minimal.
Ahmadyar et al. (Fri,) studied this question.