Non-communicable chronic diseases are now a worldwide epidemic. Diet and physical activity throughout life are among its main determinants. In countries undergoing the early stages of the nutrition transition weight gain from birth to 2 years of life is related to lean mass gain, while ponderal gain after age 2 years is related to adiposity and later diabetes and CVD risk. Evidence from developing countries undergoing the more advanced stages of the nutrition transition is limited. The early growth patterns of a cohort of Chilean children born in 2002 with normal birth weight who at 4 years had a high prevalence of obesity and CVD risk factors have been assessed. Results indicate that BMI gain in early life, particularly from 6 months to 24 months, is positively associated with adiposity and CVD risk status at 4 years. These results together with existing evidence suggest that actions to prevent obesity and nutrition-related chronic diseases in developing countries should start early in life, possibly after 6 months of age. This approach should consider assessing the effect of mode of feeding and the amount and type of energy fed, as well as the resulting growth patterns. The challenge for researchers addressing the nutrition transition is to define the optimal nutrition in early life, considering not only the short- and long-term health consequences but also taking into account the stage of the nutritional transition for the given population of interest. The latter will probably require redefining optimal postnatal growth based on the context of maternal size and fetal growth.