Changing body norms in the context of increasing body size: Samoa in 1995 and 2018.

OBJECTIVE: To understand how body size preferences changed in Samoa between 1995 and 2017 to 2019. METHODS: Data were from adults aged from 31 to 59 years, who participated in two separate cross-sectional studies of obesity and cardiometabolic risk conducted in Samoa in 1995 and 2017 to 2019. Participants nominated line drawings representing their current size, ideal size, the most attractive and healthiest size, and the lower/upper limits of "normal" size. RESULTS: In both sexes, body size preferences and perceived current average body size have increased, yet preference for bodies smaller than one's perceived current size has persisted. Furthermore, the range of body sizes that people considered "normal" has narrowed, suggesting decreased tolerance for extremes of body size. CONCLUSIONS: These findings may have implications for mental and physical health outcomes, inform development of future health initiatives, and contribute to a deeper understanding of how body norms and weight-related public health efforts interface.

Influence of weight concerns on breastfeeding: Evidence from the Norwegian mother and child cohort study.

OBJECTIVES: High body mass index (BMI) often predicts truncated breastfeeding, although why is unclear. We test a proposed mediating role of body concerns on breastfeeding initiation and child's age at weaning using longitudinal data for 55,522 mothers from the Norwegian Mother and Child Cohort Study (MoBa). METHODS: A linear regression-based mediation analysis with bootstrapping estimates the indirect effects of BMI on breastfeeding decisions (ever-initiation of breastfeeding, child's age at weaning, and duration of any breastfeeding beyond six months) through the variables of concern around prepregnancy weight and weight gains due to pregnancy. RESULTS: Contrary to prediction, Norwegian mothers with greater prepregnancy weight concerns had a higher likelihood of initiating breastfeeding. Concerns about weight gain during pregnancy, however, predicted earlier weaning. This relationship was the same for higher and lower BMI mothers. CONCLUSION: In this very large sample, body image affects some breastfeeding decisions. However, this effect is independent of mother's body size.

Weight, gender, and depressive symptoms in South Korea.

OBJECTIVES: Obesity consistently predicts depression risk, but the underlying mechanisms are poorly understood. Body concerns are proposed as key. South Korean society is characterized by extremely high levels of explicit weight stigma, possibly the highest globally. Using cross-sectional Korean 2014 National Health Examination Survey (KNHANES) data, we test this proposition in a nationally representative sample of South Korean adults (N = 5,632). METHODS: Depressive symptoms (outcome variable), was based on the PHQ-9. Weight status (predictor variable), was based on direct measures of height and weight converted to BMI. Weight concern was self-reported. Mediation analyses tested how weight concern mediated the influence of weight status on depressive symptoms for women and men. RESULTS: Current weight status influenced depressive symptoms in Korean adults, but not always directly. Concerns of being "fat" mediated that relationship. The effect increased significantly as BMI increased within "normal" and overweight/obese categories for women, and in overweight/obese categories for men. Even though women classified as underweight were significantly more depressed than those in other weight categories, there was no similar mediation effect related to weight concerns. CONCLUSION: For South Koreans, the stress of adhering to social norms and avoiding stigma related to body weight seems to explain the relationship between higher body weight and more depressive symptoms. Women are more vulnerable overall, but men are not immune. This study demonstrates that body concerns help explain why weight predicts depression, and more broadly supports the proposition that widespread weight-related stigma is a potentially major, if unrecognized, driver of population-level health disparities.

Body image mediates the depressive effects of weight gain in new mothers, particularly for women already obese: evidence from the Norwegian Mother and Child Cohort Study.

BACKGROUND: Multiple studies show that obesity and depression tend to cluster in women. An "appearance concern" pathway has been proposed as one basic explanation of why higher weights might lead to depression. The transition to motherhood is a life phase in which women's body image, weight, and depressive risk are in flux, with average weight increasing overall during this period. Examination of how these factors interact from pre- to post-pregnancy provides a means to test how body image plays a key role, as proposed, in causally shaping women's depressive risk. METHODS: Tracking 39,915 pregnant women in the Norwegian Mother and Child (MoBA) Cohort Study forward 36 months after their deliveries, we test the moderating and mediating effects of body image concerns on the emergence of new mothers' depressive symptoms by using a binary logistic regression model with a discrete-time event history approach and mediation analysis with bootstrapping. RESULTS: For women with high pre-pregnancy body mass index (BMI), weight gain heightens their depressive symptoms over time. Body image concerns mediate the association between weight gain and the development of depressive symptoms regardless of weight status. However, the mediation effect is more evident for women with higher pre-pregnancy BMI. Conversely, better body image is highly protective against the transition to mild or more severe depressive symptoms among new mothers, but only for women who were not classified as obese prior to their pregnancies. CONCLUSIONS: These findings support a role for body image concerns in the etiology of depressive symptoms during the transition to motherhood. The findings suggest body image interventions before or during pregnancy could help reduce risks of depression in the early postpartum period and well beyond.

Translating human biology (introduction to special issue).

OBJECTIVES: Introducing a special issue on "Translating Human Biology," we pose two basic questions: Is human biology addressing the most critical challenges facing our species? How can the processes of translating our science be improved and innovated? METHODS: We analyze articles published in American Journal of Human Biology from 2004-2013, and find there is very little human biological consideration of issues related to most of the core human challenges such as water, energy, environmental degradation, or conflict. There is some focus on disease, and considerable focus on food/nutrition. We then introduce this special volume with reference to the following articles that provide exemplars for the process of how translation and concern for broader context and impacts can be integrated into research. CONCLUSIONS: Human biology has significant unmet potential to engage more fully in translation for the public good, through consideration of the topics we focus on, the processes of doing our science, and the way we present our domain expertise.

Population differences in the relationship between height, weight, and adiposity: an application of Burton's model.

The study of human variation in adiposity and lean mass is important for understanding core processes in human evolution, and is increasingly a public health concern as the "obesity epidemic" expands globally. The dominant measure of population differences in adiposity is Body Mass Index (BMI), which suffers from systematic biases across populations due to variation in the relationship between true body fat, height and weight. Here we develop simplified corrections for such anthropometric-based measures of adiposity that can take into account this population variation. These corrections derive from a recent model proposed by Burton that assumes humans accrue mass in two ways-growth in height that adds bone and muscle, and growth in body fat and the ancillary fat-free mass (FFM) needed to support this additional body fat. We analyze two ethnically diverse datasets with dual X-ray absorptiometry-measured (DXA) fat mass, assessing the fit of Burton's model and deriving novel corrections based on estimated musculoskeletal slenderness. The resulting model provides excellent fit to fat mass within populations (average R2 = 0.92 for women and R2 = 0.83 for men). World populations differ dramatically in musculoskeletal slenderness (up to a difference of 4.4 kg/m2), as do men and women (differences of 3.3-4.5 kg/m2), leading to clear population corrections. These findings point to a conceptually straightforward tool for estimating true differences in adiposity across populations, and suggest an alternative to BMI that provides a more accurate and theoretically based estimate of body fat than that traditionally derived from height and weight measures.

Obesity and human biology: toward a global perspective.

Overweight bodies will soon be the modal human form. In this special issue of American Journal of Human Biology, authors use varied approaches to examine the expansion of obesity globally, particularly what shape variability in people's vulnerability to weight gain and its negative effects. The contributions together highlight how complex pathways between biology and health related to excess weight are strongly medicated, at multiple levels, by both socio-ecological context and life history. A systems approach, which can place human biological and biocultural variation iteratively within the broader contexts of developing and globalizing adiposity, will be a useful next step to informing effective prevention and intervention efforts.

Explicit versus implicit fat-stigma.

OBJECTIVES: Human biologists are increasingly engaging with current global trends toward obesity. However, little is considered about how variation in cultural views of "fat" might shape the biology of obesity, such as through pathways related to socially induced stress. Recent research indicates elevated levels of explicit fat-stigma in middle income nations, suggesting potentially high levels of psychosocial stress around "being fat." We use the case of Paraguay to test if high levels of explicit prejudice around "being fat" also suggest internalization of those ideas in ways that might predict stress effects. METHODS: Using a sample of women in Paraguay (N = 200), we test if the statement of anti-fat beliefs on standard scales correlates with similarly strong level of cognitive bias against fat based on an implicit association test. We confirm reasonable comparability of the findings to prior published studies by collecting data for U.S. undergraduates (N = 66) using the same set of tools. RESULTS: Women in Paraguay reveal high levels of explicit anti-fat bias in an interview on a standard (Attitudes to Obese People) scale, suggesting a shared cultural norm of fat-is-bad. However, Paraguayan women display, on average, no anti-fat stigma in cognitive testing. CONCLUSION: In contrast to what has been observed in industrialized nations, the high levels of explicit fat-stigma does not necessarily correlate with high levels of implicit fat-stigma. This means that pathways between obesity, psychosocial stress, and health outcomes may be very different across socioecological contexts.

Shared norms and their explanation for the social clustering of obesity.

OBJECTIVES: We aimed to test the hypothesized role of shared body size norms in the social contagion of body size and obesity. METHODS: Using data collected in 2009 from 101 women and 812 of their social ties in Phoenix, Arizona, we assessed the indirect effect of social norms on shared body mass index (BMI) measured in 3 different ways. RESULTS: We confirmed Christakis and Fowler's basic finding that BMI and obesity do indeed cluster socially, but we found that body size norms accounted for only a small portion of this effect (at most 20%) and only via 1 of the 3 pathways. CONCLUSIONS: If shared social norms play only a minor role in the social contagion of obesity, interventions targeted at changing ideas about appropriate BMIs or body sizes may be less useful than those working more directly with behaviors, for example, by changing eating habits or transforming opportunities for and constraints on dietary intake.

Nonprescription antibiotic therapy: cultural models on both sides of the counter and both sides of the border.

Antibiotic resistance is a global public health threat exacerbated by medically unwarranted or improper antibiotic use. Pharmacy counters at the U.S.-Mexico border provide an example of where lay decisions to use antibiotics in ways considered "risky" may be initiated and negotiated. We test how cultural and public health knowledge of antibiotics is distributed among pharmacy staff, local Mexican clients, and U.S. medical tourists in the bordertown of Nogales using a cultural consensus tool. We find that shared cultural models across these groups include public health statements; however, other shared statements are likely to reinforce antibiotic sales at pharmacy counters by those on both sides of the purchase as economic, rather than therapeutic, encounters. From a public health perspective, border pharmacy counters are not a location where increased "safe" knowledge about antibiotic use is being transmitted. However, we do find a positive relationship between "safe" knowledge and reductions in risky behavior.

Development and validation protocol for an instrument to measure household water insecurity across cultures and ecologies: the Household Water InSecurity Experiences (HWISE) Scale.

INTRODUCTION: A wide range of water-related problems contribute to the global burden of disease. Despite the many plausible consequences for health and well-being, there is no validated tool to measure individual- or household-level water insecurity equivalently across varying cultural and ecological settings. Accordingly, we are developing the Household Water Insecurity Experiences (HWISE) Scale to measure household-level water insecurity in multiple contexts. METHODS AND ANALYSIS: After domain specification and item development, items were assessed for both content and face validity. Retained items are being asked in surveys in 28 sites globally in which water-related problems have been reported (eg, shortages, excess water and issues with quality), with a target of at least 250 participants from each site. Scale development will draw on analytic methods from both classical test and item response theories and include item reduction and factor structure identification. Scale evaluation will entail assessments of reliability, and predictive, convergent, and discriminant validity, as well as the assessment of differentiation between known groups. ETHICS AND DISSEMINATION: Study activities received necessary ethical approvals from institutional review bodies relevant to each site. We anticipate that the final HWISE Scale will be completed by late 2018 and made available through open-access publication. Associated findings will be disseminated to public health professionals, scientists, practitioners and policymakers through peer-reviewed journals, scientific presentations and meetings with various stakeholders. Measures to quantify household food insecurity have transformed policy, research and humanitarian aid efforts globally, and we expect that an analogous measure for household water insecurity will be similarly impactful.

Weight Shame, Social Connection, and Depressive Symptoms in Late Adolescence.

Child and adolescent obesity is increasingly the focus of interventions, because it predicts serious disease morbidity later in life. However, social environments that permit weight-related stigma and body shame may make weight control and loss more difficult. Rarely do youth obesity interventions address these complexities. Drawing on repeated measures in a large sample (N = 1443) of first-year (freshman), campus-resident university students across a nine-month period, we model how weight-related shame predicts depressive symptom levels, how being overweight (assessed by anthropometric measures) shapes that risk, and how social connection (openness to friendship) might mediate/moderate. Body shame directly, clearly, and repeatedly predicts depression symptom levels across the whole school year for all students, but overweight youth have significantly elevated risk. Social connections mediate earlier in the school year, and in all phases moderate, body shame effects on depression. Youth obesity interventions would be well-served recognizing and incorporating the influential roles of social-environmental factors like weight stigma and friendship in program design.

Avoiding exercise mediates the effects of internalized and experienced weight stigma on physical activity in the years following bariatric surgery.

BACKGROUND: People living with severe obesity report high levels of weight-related stigma. Theoretically, this stigma undermines weight loss efforts. The objective of this study is to test one proposed mechanism to explain why weight loss is so difficult once an individual becomes obese: that weight-related stigma inhibits physical activity via demotivation to exercise. METHODS: The study focused on individuals who had bariatric surgery within the past 5 years (N = 298) and who report a post-surgical body mass index (BMI) ranging from 16 to 70. Exercise avoidance motivation (EAM) and physical activity (PA) were modeled as latent variables using structural equation modeling. Two measures of weight stigma, the Stigmatizing Situations Inventory (SSI) and the Weight Bias Internalization Scale (WBIS) were modified for people with a long history of extreme obesity for use as observed predictors. RESULTS: Exercise avoidance motivation (EAM) significantly mediated the association between both experienced (SSI) and internalized (WBIS) weight stigma and physical activity (PA) in this population. CONCLUSION: Exercise avoidance motivation, influenced by weight stigma, may be a significant factor explaining the positive relationship between higher body weights with lower levels of physical activity.

Employment and weight status: The extreme case of body concern in South Korea.

For an industrialized nation, obesity rates in South Korea are extremely low. Yet, reflecting an extremely fat-averse, thin-positive society, efforts to lose weight are now reportedly very common. Since the 1980s, South Korea has experienced an increasingly flexible and insecure labor market which was exacerbated by the 1997 economic recession. In this social and economic setting, body shape and weight status, as human capital, may have gained significant bargaining power in the labor market. Consequently, we propose that Koreans, particularly those who are employed in "stable" jobs (i.e., non-manual and regular jobs), would increasingly engage in intense weight management and reduction activities even when not technically overweight or obese as a means to job security and upward mobility. Using nationally-representative data from the Korean Nutrition and Health Examination Survey (KNHANES), we identify the changing role of weight concerns versus actual body weight in predicting South Korean efforts to lose weight between 2001 (KNHANES-phase 1) and 2007-2009 (phase 4). The patterns were examined by occupation type (manual and non-manual jobs) and status (regular and non-regular jobs). Oaxaca decomposition analysis supported that people's perception of being "fat," rather than actual weight status, was crucial to explaining accelerated weight management efforts in South Korea over the decade (coef. = 0.062 and p-value < .0001 for male with regular work; coef. = 0.031 and p-value = .002 for female with regular work). Occupation status, rather than employment in itself, mattered. Job stability predicted increased effort; the pattern of change through time suggests efforts to invest high levels of effort in appearance positively impacts both employment opportunity and stability.

Increasing overweight and obesity erodes engagement in one's neighborhood by women, but not men.

Obesity is socially stigmatized in the U.S., especially for women. Significant research has focused on the role that the social and built environments of neighborhoods play in shaping obesity. However, the role of obesity in shaping neighborhood social structure has been largely overlooked. We test the hypothesis that large body size inhibits an individual's engagement in his or her neighborhood. Our study objectives are to assess if (1) body size (body mass index) interacts with gender to predict engagement in one's neighborhood (neighborhood engagement) and (2) if bonding social capital interacts with gender to predict neighborhood engagement independent of body size. We used data collected from the cross-sectional 2011 Phoenix Area Social Survey (PASS), which systematically sampled residents across four neighborhood types (core urban, urban fringe, suburban, retirement) across the Phoenix Metopolitian Area. Survey data was analyzed using logistic regression for 804 participants, including 35% for whom missing data was computed using multiple imputation. We found that as body size increases, women-but not men-have reduced engagement in their neighborhood, independent of bonding social capital and other key covariates (objective 1). We did not observe the interaction between gender and bonding social capital associated with neighborhood engagement (objective 2). Prior scholarship suggests obesity clusters in neighborhoods due to processes of social, economic, and environmental disadvantage. This finding suggests bi-directionality: obesity could, in turn, undermine neighborhood engagement through the mechanism of weight stigma and discrimination.

Weight-related stigma is a significant psychosocial stressor in developing countries: Evidence from Guatemala.

Weight-related stigma is established as a major psychosocial stressor and correlate of depression among people living with obesity in high-income countries. Anti-fat beliefs are rapidly globalizing. The goal of the study is to (1) examine how weight-related stigma, enacted as teasing, is evident among women from a lower-income country and (2) test if such weight-related stigma contributes to depressive symptoms. Modeling data for 12,074 reproductive-age women collected in the 2008-2009 Guatemala National Maternal-Infant Health Survey, we demonstrate that weight-related teasing is (1) experienced by those both underweight and overweight, and (2) a significant psychosocial stressor. Effects are comparable to other factors known to influence women's depressive risk in lower-income countries, such as living in poverty, experiencing food insecurity, or suffering sexual/domestic violence. That women's failure to meet local body norms-whether they are overweight or underweight-serves as such a strong source of psychological distress is particularly concerning in settings like Guatemala where high levels of over- and under-nutrition intersect at the household and community level. Current obesity-centric models of weight-related stigma, developed from studies in high-income countries, fail to recognize that being underweight may create similar forms of psychosocial distress in low-income countries.

Genetic population structure accounts for contemporary ecogeographic patterns in tropic and subtropic-dwelling humans.

Contemporary human populations conform to ecogeographic predictions that animals will become more compact in cooler climates and less compact in warmer ones. However, it remains unclear to what extent this pattern reflects plastic responses to current environments or genetic differences among populations. Analyzing anthropometric surveys of 232,684 children and adults from across 80 ethnolinguistic groups in sub-Saharan Africa, Asia and the Americas, we confirm that body surface-to-volume correlates with contemporary temperature at magnitudes found in more latitudinally diverse samples (Adj. R2 = 0.14-0.28). However, far more variation in body surface-to-volume is attributable to genetic population structure (Adj. R2 = 0.50-0.74). Moreover, genetic population structure accounts for nearly all of the observed relationship between contemporary temperature and body surface-to-volume among children and adults. Indeed, after controlling for population structure, contemporary temperature accounts for no more than 4% of the variance in body form in these groups. This effect of genetic affinity on body form is also independent of other ecological variables, such as dominant mode of subsistence and household wealth per capita. These findings suggest that the observed fit of human body surface-to-volume with current climate in this sample reflects relatively large effects of existing genetic population structure of contemporary humans compared to plastic response to current environments.

Stigma and the perpetuation of obesity.

Even as obesity rates reach new highs, the social stigmatization of obesity seems to be strengthening and globalizing. This review identifies at least four mechanisms by which a pervasive environment of fat stigma could reinforce high body weights or promote weight gain, ultimately driving population-level obesity. These are direct effects through behavior change because of feeling judged, and indirect effects of social network changes based on stigmatizing actions and decisions by others, psychosocial stress from feeling stigmatized, and the structural effects of discrimination. Importantly, women and children appear especially vulnerable to these mechanisms. The broader model provides an improved basis to investigate the role of stigma in driving the etiology of obesity, and explicates how individual, interpersonal, and structural dimensions of stigma are connected to variation in health outcomes, including across generations.

Absolute wealth and world region strongly predict overweight among women (ages 18-49) in 360 populations across 36 developing countries.

This paper proposes a benchmark for comparing SES gradients across countries, based on gross domestic product apportioned to members of differing wealth categories within countries. Using this approach, we estimate absolute wealth in 360 populations in 36 developing countries and model its relationship with overweight (BMI≥25) among non-pregnant women ages 18-49. A simple model based on absolute wealth alone strongly predicts odds of overweight (R(2)=0.59), a relationship that holds both between countries and between different groups in the same country (10 populations for each of 36 countries). Moreover, world region modifies this relationship, accounting for an additional 22% of variance (R(2)=0.81). This allows us to extract a basic pattern: rising rates of overweight in lower and middle income countries closely track increasing economic resources, and the shape of that gradient differs by region in systematic ways.

Global convergence in ethnotheories of water and disease.

Using interviews conducted with 468 adults in nine different global locations, we tested for commonalities in how people culturally understand water-disease connections. On the basis of consensus analysis, we find evidence of shared cultural ideas about the causes and solutions to waterborne disease both within and across all locations. Causes of water-related illness with the highest salience in the different countries were comparable across sites, and mapped reasonably onto public health understandings. Comparison of specific items (statements) between public health and lay knowledge about the causes and solutions to waterborne disease showed a high level of agreement. We suggest that a straightforward, cohesive approach to water-health messaging in public health campaigns could often be the most effective point of departure, and that sophisticated cultural tailoring may be less important in regard to global waterborne disease prevention efforts than might be expected.