Mexico and other Latin American countries are currently undergoing important demographic, epidemiologic and nutrition transitions. Noncommunicable chronic diseases such as obesity, type 2 diabetes mellitus, and high blood pressure are becoming public health problems as the population experiences an important reduction in physical activity and an increase in energy-dense diets. In contrast, the prevalence of undernutrition is declining in most countries, although several decades will be needed before the prevalence drops to acceptable values. The objective of this article is to discuss the characteristics of the nutrition transition with emphasis in data from Mexico, Brazil, and Chile.