Contributors to Pediatric Obesity in Adolescence: More than just Energy Imbalance.

Disentangling the etiology of pediatric obesity continues to challenge researchers. Due to rapid growth and development, changes in the hormonal milieu, increased autonomy in feeding practices and greater interactions with environmental factors, adolescence is a particularly important period for the determination of body composition trajectories and the relationship to current and future obesity outcomes. A plethora of studies have focused on excess energy consumption and physical inactivity as they relate to weight and fat gain in adolescence. Although these "Big Two" have an impact, the increasing trends in pediatric obesity are not accounted for solely by increased energy intake and decreased physical activity. Indeed, under similar conditions of energy balance, inter-individual variation in fat accumulation has been consistently noted. It is becoming more evident that additional factors may contribute independently and/or synergistically to the increase in obesity. Such factors include (but are not limited to) metabolic programming in utero and in early childhood, the hormonal environment, endocrine disruptors, parental feeding practices, and the built environment. Our objective, therefore, is to investigate possible factors, particularly in adolescence that contributes to the increase in pediatric obesity beyond "The Big Two".