Obesity: a syndemics perspective

As of 2012 a large proportion of children and adults in the United States were considered obese, increasing their risk of a number of health problems associated with obesity, including acute injuries such as lower extremity fractures and chronic diseases like diabetes (1–3). There are various biological explanations for why people become obese, including genetics, positive energy imbalances and environmental chemical exposures (4–6). Unfortunately, these biological explanations of obesity do not encompass the chronic diseases that are associated with overweight and obesity, including type 2 diabetes (T2D), heart disease, cancer and others (5,7,8). When researchers write about obesity, they rarely limit their writings to body weight alone, frequently including these chronic conditions in their analyses despite the fact that said conditions are clinically distinct from both overweight and obesity (8–14). In order to reconcile biological theories about obesity with the chronic conditions researchers frequently associate with obesity, obesity might best be interpreted as a syndemic. A syndemic is defined as, ‘. two or more epidemics. interacting synergistically and contributing, as a result of their interaction, to excess burden of disease in a population’, and refers specifically to the health consequences of the ways in which such diseases interact (15). One of the primary initial uses of the syndemics approach was to help public health professionals understand the relationship between human immunodeficiency virus (HIV) and tuberculosis (TB), two infectious diseases that can produce a larger disease burden than the burden produced by the individual diseases when they co-occur. The syndemics approach would benefit obesity research and clinical practice in a number of ways. Primary among these benefits is that such an approach would allow researchers to more thoroughly interrogate relationships between obesity, its related conditions and social and structural factors, similar to the way that the syndemics approach has been recommended for use in analyses of the relationship between social factors, including poverty and race, and HIV (16). Consider as an example the relationship between an individuals’ neighbourhood of residence and their weight status. Both street-tree density and homicide rates have been correlated with higher obesity prevalence among pre-school-aged children, indicating that both social and structural factors can have an impact on childhood obesity (17). A similar correlational relationship has been found between recreational trails, crime and obesity among children of all ages (18). Systematic reviews have found correlations between neighbourhood design and obesity among adults (19). This area of obesity research appears ideal for the syndemics approach, as such an approach can specifically reflect the influence of the social and structural environment and its impact on disease processes and aetiology, and by doing so, help clarify methodological approaches to these contributors to obesity. This enhanced understanding could then inform clinical practice by providing practitioners better insight into how and why obesity occurs in both individuals and populations, improving clinicians understanding of obesity and their ability to effectively advise their patients. The syndemics approach to obesity would also help provide a theoretical justification for the way that many researchers currently approach obesity. This current approach often includes chronic conditions associated with obesity, including diabetes, cardiovascular disease (CVD), cancer and myriad others. For example, Wang et al.