Unhealthy eating patterns present in most Western countries pose a serious threat to economic welfare and have severe consequences for the health and quality of life of the individual consumer. The purpose of this paper is to develop and test a conceptual model for understanding how health authorities and marketers can affect consumption of healthy food – and ultimately body mass index (BMI) – by addressing perceptual antecedents of consumers' involvement and health competencies. A qualitative (n = 16) pilot study and a consumer panel survey (n = 599) assisted in completing this task. The obtained structural equation modelling results confirmed that increasing consumers' competencies concerning healthy food consumption may improve the healthiness of their food behaviour, and ultimately reduce their BMI. Notably, these effects may occur even for consumers who perceive healthy food consumption to be a challenge. Our results also revealed that it may be problematic to improve health competencies for food consumers who are less involved in healthy food consumption. However, our study shows that two perceptual factors, ‘personal food identity’ (the extent to which consumers believe that their health identity is linked to their food behaviour) and ‘unhealthy food taste belief’ (the extent to which consumers believe that unhealthy food is more enjoyable and tastier than healthy food), may assist health authorities and marketers in increasing consumers' involvement in healthy food consumption.