The human rights concept of removing obstacles to realizing rights, including the right to health, particularly among those who historically have experienced more obstacles, can enrich obesity research. It can push us to focus on the root causes of social advantage and disadvantage implicated in obesity disparities. This approach contrasts with the prevailing approach, which generally focuses on the behaviors that immediately lead to obesity without considering the factors that shape the behaviors.
Examination of social disadvantage and advantage is crucial to social disparities research. It is challenging, however, because of the limited amount of information on them in most health studies. Social advantage or disadvantage can be material, psychosocial, or both.
Material and psychosocial dimensions of social advantage and disadvantage
Social disadvantage can be based on material conditions, determined by access to resources and services that affect health such as adequate nutrition, sanitation, housing, and medical care. It also can be of a psychosocial nature, based on human relationships and their psychological effects. For example, unfair treatment based on one's race or ethnic group can cause psychological distress. In addition, one's awareness of being in a group that has historically suffered discrimination could act as a chronic stressor, even in the absence of overt incidents of unfair treatment. These dimensions often coexist and interact. Material disadvantage (eg, resulting from inadequate income or wealth) can affect obesity by influencing the ability to purchase nutritious food or to live in a neighborhood with safe, pleasant places to exercise and markets that sell affordable fresh produce. Material hardship also could increase obesity risk insofar as it is a source of chronic stress; stress could limit people's ability to change weight-related behaviors even when informed and motivated (24
). Low educational attainment could increase the risk of obesity by limiting economic opportunities or one's ability to understand and act on health information.
Racial or ethnic group is closely associated with social advantage and disadvantage and with health disparities. Although each broad racial or ethnic group is heterogeneous, overall, blacks, Hispanics, and American Indians have the lowest and Asian Americans the highest incomes and educational levels; whites have intermediate levels (27
). Racial or ethnic differences thus often reflect socioeconomic differences, which can affect health through material pathways (23
Experiences of racism could include not only overt incidents of intentional discrimination but also experiences in which unintended harm results because of deeply rooted structural arrangements, such as those perpetuating racial residential segregation. Racial segregation systematically deprives blacks and Hispanics of opportunities to live in health-promoting neighborhoods, in part by constraining their economic opportunities (5
). These experiences could deleteriously affect health outcomes both through material pathways and through psychosocial pathways involving stress and physiologic responses to stress related to awareness of unfair treatment or stigmatization (as a member of a socially excluded group). Recent advances in understanding the neurophysiology of stress and its effects on chronic disease have greatly increased our ability to understand how both material and psychosocial disadvantage can harm health (31
Any condition associated with stigma or lower social acceptance — such as obesity — could lead to social disadvantage and accompanying adverse health effects that are not intrinsic to that condition. Adverse health effects could occur through material or psychosocial pathways. Examples include physical or mental disability, HIV infection, or other highly stigmatized diseases. Similarly, nonheterosexual orientation can result in discrimination or social exclusion, putting one's health at risk in multiple ways. These experiences of discrimination are rarely measured in health studies.
Time is another dimension of social advantage and disadvantage that can be crucial to understanding health disparities. It seems likely that not only the depth but also the duration of exposure to disadvantage could matter greatly for health. Exposures that are potentially obesigenic, such as a high-calorie diet, a crime-infested neighborhood without safe places to exercise or play, or a resource-strapped school that offers children few opportunities for supervised exercise, will likely have a larger effect given a longer duration. Yet even when these factors are measured at all, time is rarely considered. Current or last year's income may be measured but generally not whether a person was poor as a child. This oversight tends to underestimate racial/ethnic disparities in social advantage. Our research with population-based data on postpartum women in California confirms that at each level of current income or education, non-Hispanic black and Hispanic women are more likely than their non-Hispanic white counterparts to have grown up in households of lower socioeconomic status (as reflected by their parents' educational attainment) (23
A disparities perspective leads us to ask about not only the antecedents of disparities in obesity but also the differential consequences of obesity for people in different social groups. Finn Diderichsen of the Karolinska Institute in Stockholm has developed a schematic diagram highlighting the dynamic nature of how health disparities are produced and reproduced over time. , adapted from Diderichsen, depicts how social position or stratification (the extent to which different groups are sorted into hierarchies of wealth, influence, and opportunities) leads to different health-promoting or health-damaging exposures for different social groups. Differences in social position influence not only whether a person is exposed to a given health risk but also differential vulnerability to disease incidence and severity and subsequent social consequences of illness. For example, a highly educated person who, because of obesity, develops heart disease with activity limitations may be less likely than a manual worker with little schooling to become unemployed. The highly educated person is more likely than the manual worker to have work that is knowledge-based, less affected by physical capacity, and more easily performed at home or on a more flexible schedule.
How health disparities are produced and reproduced across a lifetime and generations, and possible points to intervene. Adapted from Finn Diderichsen, Karolinska Institute, Stockholm; reprinted with permission.
The policy context is the outermost shell of the model. The next layer is the social context. At the top, as a part of the society stratum, an intervention can be made here by influencing social stratification. Social stratification influences social position by race and class in the individual stratum. This results in differential exposure to health hazards, and an intervention can be made here by decreasing harmful exposures (or increasing health-promoting exposures). Social position by race and class not only leads to differential exposure but also to differential vulnerability to the adverse health effects of exposure. Interventions can be made here to decrease vulnerability (or increase resilience). Exposure of a vulnerable person leads to disease or injury. Social position by race and class also results in differential consequences of disease or injury. Interventions can be made here by preventing unequal consequences. The differential social consequences of ill health result in further social stratification (linked back to the top of the model).
Diderichsen's diagram calls attention to multiple levels at which pathways toward health disparity can be interrupted by policies, from the most proximal level (proximal or downstream in relation to the outcome; eg, medical treatment ameliorating the health damage done by harmful exposures without addressing the exposures themselves) to the most distal level (policies in the social context that may blunt the degree of social stratification, such as policies supporting universal high-quality education beginning in early childhood, and poverty reduction).