Background: In many countries, doctors are recommended to provide nutrition care to patients to improve the dietary behaviours of individuals and populations. Here, we present a systematic review that aims to critically synthesise literature on nutrition education provided to medical students. Methods: In this systematic review, a literature search was done between May 1 and July 1, 2018, for articles on medical students' nutrition knowledge, skills, and confidence to counsel patients, from Nov 1, 2012, to Dec 31, 2018. Search terms related to medical students included “nutrition in medical education”, “medical nutrition education”, and “undergraduate medical nutrition education”. Search terms for topic of interest included “nutrition”, “knowledge”, “skills”, “nutrition counselling”, “confidence”, “nutrition care”, or “nutrition education”. Included studies examined any aspect of recently graduated (ie, ≤4 years) or current medical students' nutrition knowledge, attitudes, skills, or confidence (or all three) in nutrition or nutrition counselling; evaluated nutrition curriculum initiatives for medical students; or assessed recently graduated or current medical students' perceptions of nutrition education. Quality assessment appraisal of the studies was done using a Mixed Methods Appraisal Tool. Curriculum initiatives were also appraised. Findings: 66 studies were identified by the search and 24 were eligible for full-text analysis. 16 quantitative studies, three qualitative studies, and five curriculum initiatives from the USA (n=11), Europe (n=4), the Middle East (n=1), Africa (n=1), and Australasia (n=7) met the inclusion criteria. Our analysis of these studies showed that nutrition is insufficiently incorporated into medical education, regardless of country, setting, or year of medical education. Deficits in nutrition education affect students' knowledge, skills, and confidence to implement nutrition care into patient care. A modest positive effect was reported from curriculum initiatives. Interpretation: Despite the centrality of nutrition to healthy lifestyle, medical students are not supported to provide high-quality, effective nutrition care. Medical education can be enhanced by institutional commitment to make nutrition education compulsory in medical training, establishment of nutrition competencies to provide a benchmark for nutrition knowledge and skills to be included in curricula, and supported by funding for innovative curriculum initiatives. These initiatives will improve nutrition in medical training to support future doctors for the 21st century. Funding: Sir John Logan Campbell Medical Fellowship 2017, and an Australian National Health and Medical Research Council Fellowship.