Early infancy - a critical period for development of obesity.

Abundant epidemiologic evidence from the developed world now shows that more rapid weight gain during the first half of infancy predicts later obesity and cardio-metabolic risk. In countries in transition, in which stunting is still prevalent, distinguishing the effects of gain in weight from linear growth remains a challenge. Moreover, very few studies to date have incorporated body composition measures during infancy, which is key to understanding determinants of infant weight gain that also predict later obesity. In addition to infant feeding type, potential determinants include the perinatal endocrine milieu. Animal and emerging human data raise the possibility that ensuring adequate leptin exposure to the growing fetus may regulate energy balance as the infant grows. Understanding these pathways, as well as examining the balance between cardiovascular and cognitive effects in both term and preterm infants, will point the way toward effective interventions to alter infant growth to prevent later obesity.