Clear specification of obesity prevention goals is essential in shaping an action plan and evaluating its success. Pertinent issues for setting obesity prevention goals for populations include concepts of optimum population BMI and healthy weight levels, potential effects on food intake and patterns of physical activity and inactivity (the primary modifiable determinants of obesity), as well as attitudes and social norms related to food and eating, physical activity and inactivity, body size, and dietary restrictions (WHO, 2000; Kumanyika et al., 2002). For children and youth, these considerations must be framed not only within the context of healthy physical, psychological, and cognitive development but in recognition that the increased prevalence of childhood obesity has broadened the emphasis of dietary guidance to address the overconsumption of energy-dense foods and beverages and physical activity patterns (ADA, 2003, 2004).
For individual children and youth, obesity prevention goals focus on maintaining energy balance (calories consumed versus calories expended). As discussed in greater detail later in the chapter, this involves engaging in healthful dietary behaviors and regular physical activity. Healthful dietary behaviors include choosing a balanced diet, eating moderate portion sizes, and heeding the body’s own satiety cues that indicate physiological fullness. It is currently recommended that children and adolescents accumulate a minimum of 60 minutes of moderate to vigorous physical activity each day (see section on physical activity).
Children’s food and beverage intake and their physical activity and sedentary behavior patterns can be influenced by a variety of environmental factors, including the availability and affordability of healthful foods, advertising messages, and opportunities to participate in physical activity within communities (Richter et al., 2000). Although individuals and families are embedded within broader social, economic, and political environments that influence their behaviors and may either promote or constrain the maintenance of health (IOM, 2001), such environments may also serve as contexts for change. These are the settings in which relationships are formed (e.g., home environment and support networks), and they represent a collection of formal and informal community institutions that monitor the behavior and safety of residents (Leventhal and Brooks-Gunn, 2001).
As will be noted throughout this report, changing the social, physical, and economic environments that contribute to the incidence and prevalence of childhood obesity—especially in populations in which the problem is longstanding and highly prevalent—may take many years to achieve. Therefore, the committee acknowledges that numerous intermediate goals, involving step-by-step improvements in diet patterns and physical activity levels of children and youth, are necessary for assessing progress. The ulti-