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Bridging the Evidence Gap in Obesity Prevention: A Framework to Inform Decision Making
from a population perspective. The logic of obesity prevention when undertaken by different sectors and at different levels is then examined using an overarching model developed by a prior Institute of Medicine (IOM) committee on child obesity prevention. Specific obesity prevention approaches are next identified across a spectrum that includes changes in policy and legislation, organizational practices, community and neighborhood environments, and health care settings, as well as strategies based on health communication or health education and individual counseling. Examples of how these strategies are combined in multilevel approaches are also provided. The chapter concludes by placing strategies being used to address obesity prevention in the context of those used to address other complex public health problems.
Approaches discussed in this chapter draw on accounts of current practice, policies, and programs that have been implemented or recommended as being potentially pertinent to obesity prevention. Background information on concepts and evidence for assessing the effectiveness of the approaches presented here is provided in Chapter 3.
DEFINITIONS AND TYPES OF PREVENTION
The concept of increasing obesity prevalence caused by a shift in the population distribution of BMI was shown in Figure 1-1 in Chapter 1, based on actual data for adults in the U.S. population. From a population perspective, obesity prevention means reversing this shift—lowering the mean BMI level and decreasing the incidence of obesity, that is, the rate at which people enter the upper end of the BMI distribution (Kumanyika et al., 2002; WHO, 2000). Stabilization of the BMI distribution or the incidence of new people crossing the relevant BMI threshold (30 kg/m2 for adults or the 95th sex–age percentile of the BMI reference for children) would be the first sign of success, followed by a decline in these indicators. Within the population, accomplishing this will require that adults at a healthy weight (i.e., not underweight, overweight, or obese) maintain that status and avoid the phenomenon of excess weight gain that commonly accompanies aging. For children, prevention means maintaining a healthy weight trajectory and preventing excess weight gain while growing, developing, and maturing. Prevention for individuals who are already overweight or obese can be defined as avoiding progression to a more severe level of obesity and/or preventing or delaying the onset of obesity-related medical conditions (IOM, 1995).
A 1995 IOM report on criteria for evaluating weight management programs emphasizes the importance of giving greater priority to obesity prevention in light of the increases in population weight levels and obesity prevalence (IOM, 1995). Although that report focuses primarily on setting standards for individually focused weight management programs, the committee that produced it set the stage for thinking about levels of prevention from a population perspective. Instead of the primary, secondary, and tertiary prevention terminology, based on a continuum of disease