2002; Richardson et al., 2003). In a nationally representative sample of 8-to 11-year-olds, clinically meaningful behavioral problems have been shown to be associated with the development of obesity over a 2-year period among children not obese at baseline (Lumeng et al., 2003). Affective factors, such as depressive symptoms, are also the likely mediators of the observed association between adult obesity and traumatic childhood experiences (e.g., physical abuse, sexual abuse) (Williamson et al., 2002).
There is accruing evidence that even the metabolic syndrome itself may be a consequence of how the brain processes environmental stimuli that are social in nature. For instance, the brain’s response to stress may alter the hypothalamic-pituitary-adrenal (or gonadal) axis in a way that promotes central fat deposition and insulin resistance in adults (Bjorntorp, 2001). Because children also experience stress, the part of the brain that regulates emotion may not only influence whether a child overeats, but also the metabolic consequences of that excess energy.
The fact that the physiologic response to stress is conditioned in childhood (Gunnar and Donzella, 2002) emphasizes the potential importance of optimizing the social and emotional health of children as a strategy for preventing obesity over a lifetime. Failure to recognize this connection between social or emotional health and physical health could result in prevention strategies that are poorly conceptualized, and underscores the need to consider the broadest possible definition of health to include the physical, mental, and emotional aspects (Table 2-1), because the foundations of all three develop during childhood and are interconnected.
A RAND study has calculated that the costs imposed on society by people with sedentary lifestyles (i.e., the “external” costs generated) may be greater than those imposed by smokers (Keeler et al., 1989). More recent computations of national health-care expenditures related to obesity and overweight in adults showed large lifetime external costs related to these conditions. After adjusting for inflation and converting estimates to 2004 dollars, the national direct and indirect health-care costs related to overweight and obesity range from $98 billion (Finkelstein et al., 2003) to $129 billion (DHHS, 2001a).6 It has been suggested that overweight and obesity may account for nearly one-third (27 to 31 percent) of total direct costs related to 15 co-morbid diseases (Lewin Group, 2000) and account for 9