Wilma Freire, Co-Director of the Institute for Research in Health and Nutrition at the San Francisco University of Quito, and who was Head of the Nutrition Unit of the Pan-American Health Organisation, led a multidisciplinary and inter-institutional team for the conduct of the Ecuadorian population, the largest survey on health and nutrition. In Volume I, Dr Freire and its team provide us with a detailed description of the conceptual and methodological aspects of ENSANUT-ECU 2012, and focus the analysis on the health and nutrition outcomes of the population aged zero to 59, leaving to Volume II the results on sexual and reproductive health of women and men of reproductive age, as well as data on use and spending on health services.