Childhood obesity: Adrift in the "Limbic Triangle"
The prevalence and severity of childhood obesity have increased steadily over the post three decades. The human species evolved to rigorously defend its lower limit for weight and adiposity but is tolerant of the upper limit, which, until recent times, was rarely approached. Neuroendocrine mechanisms within the limbic core of the brain prevent starvation (ventromedial hypothalamus), heighten reward (ventral tegmental area and nucleus accumbens), and attenuate stress (amygdala), in order to promote food-seeking and ingestive behavior and to conserve energy output. In a stressful modern environment with ready access to calorie-dense, highly palatable foods and limited venues for activity, normal, reflexive responsiveness to these three drives makes weight gain all but inevitable. The obesity that ensues often engenders insulin resistance, which undermines the ability of normal hunger and satiety signals to accurately modulate energy intake versus expenditure. Obesity interventions that rely on cognitive information alone cannot free children from this "limbic triangle." Integrated multidisciplinary family- and community-based education, effective stress reduction, and a societal commitment to alter the food and built environments are all necessary components to battle the global obesity epidemic.