The committee identified a primary prevention, population-based approach to be the most viable long-term strategy for reducing obesity and its chronic disease burdens. Examples of the effectiveness of primary prevention interventions include smoking cessation to reduce lung cancer incidence, condom use to lower HIV transmission, and fruit and vegetable consumption to prevent cancer and cardiovascular diseases (CVDs) (Kroke et al., 2003; WHO, 2003).

There is no single acceptable standard, however, for assessing the entire range of prevention interventions and programs (Kellam and Langevin, 2003). Each phase of prevention research involves specific criteria for evidence and a variety of possible research designs. This is often a process whereby the preceding phase of research informs the subsequent generation of research—from efficacy to effectiveness, sustainability, going-to-scale, and, finally, sustaining system-wide⁹ (Figure 3-3). Numerous evidence-based prevention strategies are currently being used, though their focus—whether on individuals, institutions, or societal structures—can vary (Kellam and Langevin, 2003).

Evidence-based medicine is a valuable concept for informing clinical medicine that provides universally accepted standards for testing the scientific method and developing clinical practice guidelines (Harris et al., 2001; Heller and Page, 2002). This approach uses an accepted hierarchy of evidence—in accordance with its type, quality, and strength—to support recommendations (Table 3-3) (Harris et al., 2001; Kroke et al., 2003), and it establishes a cause-and-effect relationship guided by the principles of predictability, replicability, generalizability, and falsifiability. Predictability depends on a properly implemented intervention producing expected outcomes, a clear understanding of the intervention’s elements, and a cause-and-effect interaction among those elements (Tang et al., 2003). Replicability and generalizability rely on an intervention’s potential for