A Complex Systems Approach to Understanding and Combating the Obesity Epidemic

This CSED Working Paper will be included in the forthcoming "Obesity Prevention" book.

Abstract

The obesity epidemic represents a major and rapidly growing public health challenge, in the United States, and worldwide. The scope and scale of the obesity epidemic highlight the urgent need for well-crafted policy interventions to prevent further spread and (potentially) to reverse the tide. Yet several characteristics make obesity an especially challenging problem both to study, and to combat. I show that these challenges—the great breadth in levels of scale involved, the substantial diversity of relevant actors, and the multiplicity of mechanisms implicated—are characteristic of complex adaptive systems. I argue that the obesity epidemic represents such a system, and that both general lessons and techniques from the field of complexity science can help inform effective policy to combat obesity. In particular, I argue that the technique of agent-based computational modeling is especially well suited to the study of the rich and complex dynamics of obesity.

Background

The obesity epidemic represents a major and rapidly growing public health challenge, in the United States, and worldwide. Between 1970 and 2000, for example, the percentage of Americans classified as obese doubled to almost 30% (Bray, Bouchard and James 2003), with fully two-thirds of American now classified as overweight (Ogden 2006). The problem of obesity is not limited to the American context—similar epidemics of obesity are underway across the globe, from Europe to South America to the Middle East and Asia (see, for example, Rennie & Jebb 2005; Cameron et al. 2003; Yumuk 2005; Mohammedpour-Ahranjania et al. 2004; Kain et al. 2002; and Albala et al. 2002). Overall, nearly half a billion worldwide were overweight or obese in 2002 (Rossner 2002).

These sharp increases in obesity rates have significant implications for public health, since obesity is linked with diabetes, high blood pressure, and high cholesterol (NHLBI 1998). In addition to higher mortality/morbidity, obesity increases health care costs dramatically (Finkelstein et al. 2005)—some estimates suggest that obesity-related medical expenses accounted for as much as 9% of total U.S. medical expenditures in 1998 (or roughly $78.5 billion), a proportion that is expected to increase (Finkelstein, Fiebelkorn, and Wang 2003).