We explore the relationships that future teachers establish between food consumption and sustainability, as well as their intentions to act and their competences in ESD, after a training program. Three instruments were designed and analyzed within the methodological framework of qualitative content analysis. The results showed that, although the future teachers set adequate relationships, they still had significant difficulties in accepting the need for ambitious changes in their diets. Their educational proposals are focused on the diagnosis of the problems instead of the assessment of the sustainability of eating habits and the empowering of learners to take responsible decisions and actions.