Dietary intake is an important contributor to the obesity epidemic in children and adults, but the long-term effects of dietary interventions after obesity has occurred are modest at best. Childhood obesity significantly increases the risk of adult obesity. It has been suggested that prior to puberty, the interaction of physiological and dietary intake factors greatly affects overall trajectory of weight gain of the life course. This review article summarizes research on the role of diet on weight and metabolic outcomes, and it suggests how dietary interventions prior to puberty may decrease the prevalence of obesity life span. Specifically, presented literature examines dietary intake in early life and through the pubertal transition, as well as the role of macro- and micronutrients in mechanisms that influence fat accumulation and storage. The evidence suggests that multiple early life periods for dietary interventions could have a cumulative effect on optimizing tissue partitioning and limiting excessive fat accumulation into adulthood. Prior to the pubertal transition, it appears that improving diet quality in the context of energy balance may also be a key strategy for preventing current and future obesity. © 2009, SAGE Publications. All rights reserved.