Obesity among Poor Americans: Is Public Assistance the Problem?

5. The "Factor X Causes Both Public Assistance and Obesity" Hypothesis

115 5 The“Factor X Causes Both Public Assistance and Obesity”Hypothesis Factors in addition to poverty may cause both obesity and public assistance participation. Disabling physical disorders and mental illness limit the ability to earn income and can pose barriers to physical activity and a nutritious diet. Abuse in either childhood or adulthood may lead to both physiological and psychological responses that raise the risk of poverty, public assistance receipt, and obesity. Low intelligence and high time preference could impede the ability to consider the future consequences of current actions and thus lead to both poverty and obesity. This chapter reviews these five possible variables, which I generically refer to as “Factor X,” that could contribute to the association between public assistance and obesity (Figure 5.1). Research Context Given that mental illness, low intelligence, and abuse are potential pathways in this model, it’s not surprising that psychologists, psychiatrists, and other physicians dominate the research relevant to this chapter. They develop tools for assessing intelligence and mental health, and study the causes and consequences of these conditions. Researchers from these disciplines have also done much of the work on the impact of abuse, along with sociologists, social workers, and legal scholars. Epidemiologists , psychologists, and sociologists lead the research on examining connections between intelligence and health. Finally, economists join the psychologists and psychiatrists in studying humans’ ability to delay gratification, or time preference, and how it might influence obesity status. Measuring mental health, intelligence, and time preference present substantial technical problems that require a trade-off between accuracy and generalizability. Studies using multiple measures and in-depth interviews offer greater accuracy, but they also require considerable time and money, and thus are usually used only in studies of smaller, geo- 116 Obesity among Poor Americans graphically limited samples. Larger, more representative studies rely on fewer measures, offering greater generalizability at the price of reduced accuracy. Researchers studying time preference and domestic violence prevention can conduct some random experiments; those studying the impact of mental illness, disability, and intelligence on health and poverty status cannot. Consequently, many of the available studies on possible X factors rely on cross-sectional data, which don’t allow tests for causality. Some longitudinal studies are available, and they offer the best insight into whether mental illness, disability, and intelligence cause both poverty and obesity. Empirical Evidence: Possible X Factors Physical and Intellectual Disabilities Physical and intellectual disabilities can be inherited or may result from disease and injury. According to a report by the Centers for Disease Control and Prevention (2002), obesity is much more prevalent among the disabled than the non-disabled (Figure 5.2). This pattern could arise because obesity causes disability (as discussed in Chapter 3), or because disability causes obesity, or both. Why might disability lead to obesity? First, the biological foundations for some disabilities may predispose individuals to obesity. For example, two genetic disorders that impair mental abilities, Down syndrome and Prader-Willi syndrome, are also associated with obesity. Second, the disabled are less likely than those without disabilities to engage in regular physical activity, probably because is it harder for them to do so (CDC, n.d.). Third, the disabled may consume a less nutritious diet than the non-disabled because they face greater barriers to acquiring and preparing food on their own and frequently rely on meals provided by caregivers. Unfortunately, little research has examined the diets of the disabled in either institutional or community settings. Draheim et al. (2007) analyze the food intake of 325 mentally retarded adults and find that in community living arrangements they consume less than the recommended amount of fruits and vegetables, and that the proportion who eat an adequate amount of these foods falls below that of the general population.1 Residents also consume more than the recommended amount of fat, but the prevalence of high fat diets is similar to that of the general population. Longitudinal studies on the timing of disability and obesity onset, which would suggest the direction of causality, have not yet been published. So while we know that the disabled are more likely to be obese, and we The“Factor X Causes Both Public Assistance and Obesity”Hypothesis 117 have theoretical reasons why disability may lead to obesity, we don’t have enough evidence to conclude that disability causes obesity. Can disability lead to poverty and public assistance participation? It seems logical that people with...