They found that obesity increased with a nation's economic development, but also that socioeconomic status in relation to obesity changed. In low-income countries, people with higher socioeconomic status were more likely to be obese. Conversely, in high-income countries, people with higher socioeconomic status were less likely to be obese. Nutrition Obesity Research Center, Ryals Public Health Building, Room 140J, University of Alabama at Birmingham, 1665 University Boulevard, Birmingham, Alabama 35294 Albert J.
Stunkard's influential career in obesity research spanned more than fifty years and included several landmark studies on social factors related to obesity. This review discusses Stunkard's important contributions to research on the relationship between socioeconomic status SES and obesity, the extensions of his work, and reflects on Stunkard's role in mentoring the generations of scientists who succeeded him. In the US, research on health disparities has often focused on differences between races and ethnicities, in contrast to European research on health disparities, which has a longer tradition of collecting and reporting on differences in health by social class (...). Stunkard played a pivotal role in promoting the scientific study of SES and its effects on health in the United States by demonstrating that the relationship between SES and obesity is not simply due to individual traits (1.Although Stunkard's contributions are numerous, this review focuses on one aspect of his legacy research the relationship between SES and obesity his early research and use of innovative methods to disentangle the social from the biological.
We conclude with a series of personal reflections by David Allison on Stunkard's influence and why contemporary researchers will continue to benefit from Stunkard's 'beginner's mind' in the complex world of obesity science. The worldwide increase in the prevalence of obesity is a public health challenge due to the associated health risks and mortality (15-1 , the increased health care costs (1 , and the increased number of people susceptible to weight-related discrimination (20-2.Indeed, Stunkard contributed to research on the stigmatisation of obesity throughout his career, helping to reproduce a 1961 study of children's preferences that showed that depictions of obese youth were consistently the least liked among drawings of children with various disabilities (2).While biases against other types of disabilities remained stable or decreased relative to the 1961 study, biases against obese children increased (2).Before reviewing Stunkard's use of twin and adoption studies to demonstrate the effects of both "nature" and "nurture" on weight, we will discuss contemporary research on the relationship between SES and obesity, sex and race-ethnicity differences in the observed association, and contemporary issues in the measurement of SES issues that continue to be informed by, and extend, Stunkard's research. Stunkard was one of the first to identify that the association between SES and obesity was more consistent among women than among men; indeed, among men in developed countries, Stunkard observed that the relationship between SES and obesity was as likely to be negative as positive (2). Stunkard's own research (9,30) also suggested strong and consistent inverse relationships between SES and obesity among women, but inconsistent relationships for men and children.
Among boys, 35 e of the studies originally reviewed found no association between SES and obesity among girls, and 41 e of the studies reviewed found no association among boys. McLaren (200) and Cohen (201), in their consideration of the cultural and economic context in which SES may influence weight outcomes, trace their research directly back to Stunkard. Although Stunkard identified nuances in the relationship between SES and obesity according to a country's economic development, gender and age, noted limitations of Stunkard's early observational work include reliance on cross-sectional data; reliance on weight or body mass index rather than more direct measures of adiposity; limited operationalisation of SES; and racial-ethnic differences in the association are little discussed. Although the causal direction of these associations is uncertain, there are theoretical reasons to suspect that SES has a causal effect on weight.
SSS may be an indicator of financial insecurity and desire for money, which is associated with increased consumption of tasty, energy-dense foods (40). Over time, individuals with low SSS may engage in diet-related behaviours that, in the long term, result in a positive energy balance and weight gain. An interesting set of observations connects the relationship between adiposity and social status (both objective and perceived) with evolutionary thinking. First, humans are not the only animals among which this relationship exists.
It has also been observed in several non-human primate species (4), birds (4) and rodents (4). In some cases, the reason seems obvious. For example, in times of food scarcity, more dominant birds may raid the caches of lower-ranking birds and, therefore, when food appears scarce, lower-ranking birds increase their body fat reserves more than higher-ranking birds (4).When faced with environmental and social feedback that leads us to perceive that our access to resources is insecure and that others are more powerful and may prevent our access to future resources, it may be prudent to store as much body energy for the future as possible; indeed, some have hypothesised that obesity is an adaptive response to food insufficiency (4).In particular, economic insecurity is associated with obesity (4), short-term vicarious social defeat has been shown in controlled experiments to lead to increased food intake (50), and people who report experiencing "food insecurity" ironically tend to be fatter than those who do not report food insecurity (5), observations that are consistent with the hypothesis that energy storage increases in response to the perception that resources are insecure or scarce. In particular, this line of thinking places the perception of one's social rank (as opposed to mere material purchasing power) in a hypothesised key role in the causal connection between SES and adiposity.
Unfortunately, experiments such as the Moving to Opportunity Study (5) are rare, and in many cases randomisation is neither practical nor ethical, so researchers must turn to other methods to reduce confounding beyond simple association designs. To advance the field beyond Stunkard's initial contributions, we must improve causal inference; however, how do we overcome the challenges of randomisation and blinded treatment? Since Stunkard's original Midtown Manhattan study, several non-experimental methods have been used to test the causal effects of SES on weight, including the use of changes in compulsory school laws, (53-5 , sibling fixed effects designs (5 , and timing of school entry (5.Other non-standard RCT designs such as cluster randomisation (5 , instrumental variables analysis (5 , and propensity score analysis (60) have also been developed and applied since Stunkard's original pure observational studies (5). Stunkard was well aware of the limitations of standard observational studies, and sought new methods to test for causal effects of environmental exposures on adult weight outcomes, and to compare the relative effects of environmental exposures with innate and genetic effects on weight. In one such study, conducted with one of the authors of this manuscript (6), Stunkard and Allison analysed two different large adoption studies, one from Denmark and one of Korean children adopted into American homes, as forms of quasi-randomised experiments (5).Following this assumption, if aspects of the matched rearing environment correlate with post-mismatch outcomes, one can conclude with reasonable confidence that that factor, or some aspect of the rearing environment associated with that factor (but not factors related to offspring prior to matching) has a causal influence on the outcome.
The results indicated that, although the adoption datasets differ in many respects, shared genetic factors and direct environmental causality contribute almost equally to the association between rearing environment SES and offspring BMI. The results of these and similar studies provide insight into one of the oldest philosophical debates in the social and psychological sciences: the nature versus nurture debate (a phrase coined by Francis Galton, the father of quantitative genetics); and Stunkard was one of the first to address the issue with respect to body weight. At a time when conventional wisdom held that obesity was caused by the failure of an individual's willpower, Stunkard published two pioneering articles in the New England Journal of Medicine that offered a relatively novel perspective. In the first, published in 1986, he found that the weight of Danish adoptees in adulthood was similar to that of their biological parents, but not at all to that of their adoptive parents (.
The second study, published in 1990, found that Swedish identical twins, whether raised together or separately, had nearly identical BMIs (6.Both papers provided considerable support for the argument that "nature" exerted a greater influence on obesity than "nurture". Stunkard's willingness to explore both environmental and non-environmental influences paved the way for subsequent and ongoing research. Stunkard conducted his research at a time when the tradition was simply to juxtapose the effects of nature and nurture, and researchers tended to estimate the extent to which nature and nurture contributed to a given outcome at a given time. For example, based on the results of twin studies, Stunkard estimated that 60-80% of weight could be attributed to genetics (6).
Current research and theories on obesity take into account the extent to which nature and nurture interact, rather than compete, in contributing to obesity, and how they do so over time, both in terms of individual and societal development (6).Stunkard had several distinctive characteristics that permeated his social interactions and defined him as a special person and an outstanding scholar. One of these was his unquenchable thirst for new ideas, new methods and new data. He was always asking questions, like an intelligent but naïve child, childlike but not childish. Secondly, he had an infectious enthusiasm, which was visible whenever a scientific discussion began.
Thirdly, he had a sincere humility and was comfortable playing the role of the wide-eyed "inquisitive student", even if the "professor" he was questioning was more than half a century his junior. This excitement to learn new things, his ease in admitting a new idea into his thinking without the encumbrance of previous thinking, the willingness to "play at being one and learn from anyone else were some of his greatest strengths as a scientist and typify the "Beginner's Mind" he learned from his Zen master, Suzuki (6).How can we who have dedicated our lives to research and teaching affirm and convey the value and excitement of learning for its own sake to our students in a world that increasingly urges them to think of their education in instrumental terms, urges them to focus on narrowly defined achievements and material outcomes?(6 Mickey's generosity to young researchers is legendary and I was but one of the many beneficiaries. He was not only a great scientist, but also a great man. Stunkard with colleagues, including one of the authors (far left) at the Columbia Obesity Conference, April 1993 Dr Stunkard with colleagues at the Ciba Foundation Symposium on The Origins and Consequences of Obesity Compliance with ethical guidelines Dwight W.
Lewis declares no conflict of interest Human and animal rights and informed consent National Center for Biotechnology Information, U, S. National Library of Medicine 8600 Rockville Pike, Bethesda MD, 20894 USA. Low socioeconomic status of families is associated with increased rates of childhood obesity. Despite modest recent improvements in obesity rates among low-income US preschool-aged children16 , obesity rates remain higher among low-income children, 17 However, this trend is not consistent across races and SES levels, 18 Some attribute the higher rate of obesity in minorities to their higher rates of poverty, 19 However, studies show that black children with higher SES do not show the trend of lower obesity prevalence than white children with higher SES, 18,20,21 In this study, we used a large national database to assess whether SES modifies risk factors for childhood obesity, including race. With this knowledge, healthcare providers caring for racial minority children can better address obesity in their paediatric patients by understanding the relationship between race, modifiable risk factors, SES and childhood obesity.
Psychological distress and subsequent emotional eating represent a serial pathway linking low socioeconomic status and obesity. Tackling these maladaptive coping behaviours may be a strategy to reduce obesity in low-income populations. In the Midtown Manhattan study, Goldblatt, Moore ( observed that women experiencing downward social mobility had a higher prevalence of obesity (22%) compared to those experiencing upward social mobility (12%). Among those with incomes below the poverty level, the prevalence of obesity increased from 34.5% to 42.0% (Figure.
Native American children were almost twice as likely to be overweight or obese compared to white children. The present study shows that the relationship between SES and obesity may be partly explained by psychological distress and subsequent emotional eating as a coping strategy. Although portion size is known to be associated with a higher prevalence of obesity20 , the relationship between portion size and SES and the role of portion size as a mediator of the SES-obesity relationship has not previously been established. A recent systematic review found that a number of neighbourhood characteristics, such as walkability and greater access to physical activity facilities and supermarkets, were associated with a lower risk of obesity, while access to fast food outlets has been associated with an increased risk of obesity.
Differences in the neural response to food in obesity-resistant versus obesity-prone individuals. Recent research ( showed how socioeconomic disparities in body weight in children and adolescents have reversed over time; in the 1940s through the 1970s, lower socioeconomic status was associated with lower weight; however, in 2001, lower socioeconomic status was associated with higher weight. The scatter plots illustrate the association between the obesity rate and the percentage of people living below the poverty level (Figure 1, R2=. This data brief presents the most recent national data on obesity in US adults and its association with the poverty income index (PIR) and educational attainment.
PROC GLM was used to determine the significant difference in obesity between states, followed by the standardised TUKEY test for further classification. Most research on nutritional and health disparities has focused on cultural, socioeconomic and structural differences in ethnic groups, and attempts to explain these observed socioeconomic disparities, particularly in obesity, have focused primarily on the role of energy-balancing behaviours and, to a lesser extent, psychosocial factors such as stress, self-esteem and the social environment, including culture, social networks, norms and support. The relatively low cost of fast foods, as well as other energy-rich and nutrient-poor foods, compared to the price of fruits, vegetables, whole grains, low-fat dairy products and lean meats, is a barrier that may affect food choices. However, several obesogenic behaviours are independent of SES and appear to be more strongly linked to interoceptive differences in satiety.
