Introduction: Nutrition has been underrepresented in the curriculum of many medical schools and therefore physicians do not feel adequately prepared to provide dietary counselling. The aim of the present study is to determine the impact of a Nutrition and Metabolism curricular unit on nutrition attitudes, knowledge and confidence on future clinical practice of medical students.Material and Methods: All the students enrolled in the curricular unit (2017/2018) were invited to complete a questionnaire assessing their nutritional knowledge and eating habits at the beginning and at the end of the semester (n = 310).Results: Initially, students reported good eating habits and nutrition knowledge. These aspects improved at the end of the study. Moreover, students reported that they felt more confident to do dietary counselling after intervention.Discussion: Most medical students answered affirmatively to all questions related with good habits or eating behaviours, and the acquisition of knowledge had an impact in specific attitudes. After the Nutrition and Metabolism classes the students felt able to provide dietary counselling in different clinical settings, but none of the students felt extremely confident about their competencies for dietary counselling. This can be due to the fact that the students involved were in the first year of the integrated master’s degree in medicine, which is a preclinical year, and thus distant from the medical reality and from contact with patients.Conclusion: Nutrition education can have a positive impact on attitudes and eating behaviours, knowledge and in the perception of competencies for dietary counselling.