Influence of qualitative menu labeling on diners' food choices: A controlled quasi-experiment in self-service buffet restaurants.

Menu labeling is a strategy to promote healthier food choices in restaurants. This study aimed to analyze the influence of a qualitative menu labeling on the healthfulness of diners' food choices in self-service buffet restaurants. A controlled quasi-experiment comparing parallel groups at baseline and intervention periods was conducted in a control restaurant and an intervention restaurant. Qualitative labels provided information on the name and ingredients list of the dish, highlighting the use of organic vegetables. The same food menu was served in both restaurants. Menu labeling was implemented at the intervention restaurant for six dishes each day, three considered healthier and three less healthy. Dishes were weighed at the beginning and at the end of the service to estimate the average portion size (g) of diners, during five consecutive days at baseline and intervention. Diners who had lunch at the intervention restaurant were invited to participate in a survey on the use of menu labels. Of the 153 interviewed diners, 31% reported noticing menu labels. Of these, 57% said menu labeling had influenced their food choices at the restaurant. No changes in portion sizes were observed between baseline and intervention periods within control and intervention restaurants. However, it was found that the provision of qualitative menu labeling sparked the interest of restaurant managers in improving meal quality and modifying recipes to eliminate ultra-processed ingredients. Thus, the implementation of the proposed menu labeling model can promote healthier food choices through the reformulation of culinary recipes. However, it is essential to adopt strategies to enable its direct impact.