AbstractObjective:The study aimed to assess the impact of a game-based nutritional intervention on food consumption, nutritional knowledge and self-efficacy in the adoption of healthy eating practices.Design:This cluster randomised controlled trial included both male and female high school students from private schools in the Federal District, Brazil. Four schools were randomly selected for each group. Investigated variables were age, sex, monthly family income, maternal education level, dietary perceptions and practices, nutritional knowledge and self-efficacy in the adoption of healthy eating practices.Setting:Intervention group participants were instructed to play Rango Cards, a digital game developed for the study, on their own, for a period of 7–17 d, while the control group was not provided with any game or material during the study.Participants:The study included 319 adolescents (mean age = 15·8 (sd 0·7) years).Results:Significant reductions were observed in the intervention group compared with the control group for the following variables: habit of eating while watching TV or studying and having meals at fast food restaurants. The intervention group showed increased knowledge of the effects of fruit and vegetable consumption as well as improved self-efficacy in the adoption of healthy eating practices such as reducing Na intake and preparing healthy meals.Conclusions:The design of Rango Cards is potentially capable of effecting positive changes. Therefore, the digital game promotes autonomy and self-care among adolescents with regard to healthy eating.