Explained and unexplained regional variation in Canadian obesity prevalence

The objective of our study was to examine sociodemographic and behavioral variables underlying the geographic variation of obesity in Canada. We aimed to quantify the share of regional variation in average BMI attributable to commonly cited determinants of obesity and the remaining share, which is attributable to the idiosyncrasies of the regional environment ("regional effects"). Using data from the Canadian Community Health Survey (CCHS) (2004), ordinary least squares (OLS) regression, and Blinder-Oaxaca decomposition to decompose the difference in mean BMI between regions, we quantify two parts of the difference: a share explained by different levels of the covariates and a share explained by those covariates having different effects on BMI in the different regions, using the Atlantic provinces as the reference group. We observed that some differences (e.g., average BMI for males in Quebec compared to the Atlantic provinces) are mostly explained by the different levels of socio-demographic and behavioral covariates, while others (e.g., average BMI for females in Quebec compared to the Atlantic provinces) are mostly explained by the different effects of the covariates on BMI. In the latter scenario, even if covariates were made to be identical in the different regions, the difference in average BMI would persist. Thus, targeting covariates in different regions through plans like physical activity or nutrition policy, income equalization, or education subsidies will have ambiguous effects for addressing disparate obesity levels, being plausible policy options in some regions but less so in others. Future research and policy would benefit from identifying these region-specific attributes that have local implications for BMI.     

Gender Differences in Body Satisfaction

PINGITORE, REGINA, BONNIE SPRING, DAVID GARFIELD. Gender differences in body satisfaction. Although men and women show similar rates of obesity, women more frequently engage in weight loss efforts, with potentially adverse health consequences. We surveyed 320 college-aged men and women to examine gender differences in the determinants of body dissatisfaction and the degree of importance assigned to body-weight and shape. Results indicated that, for both genders, satisfaction with bodyweight and shape decreased as body mass index (BMI) increased. Women, however, showed significantly greater body and weight dissatisfaction than men at most weight categories. Only the underweight (BMI<20) women and men were similarly satisfied with their bodyweight and shape. As BMI increased, however, women became disproportionately more dissatisfied: both normal-weight and overweight women expressed greater dissatisfaction than comparable men. College-aged women also attributed progressively more importance to both weight and shape as BMI increased, unlike college-aged men, who considered body weight equally important to (or slightly less important than) self-esteem as BMI increased. We discuss implications for the self-esteem of obese women and men.     

Accounting for post-randomization variables in meta-analysis: A joint meta-regression approach

Meta-regression is widely used in systematic reviews to investigate sources of heterogeneity and the association of study-level covariates with treatment effectiveness. Existing meta-regression approaches are successful in adjusting for baseline covariates, which include real study-level covariates (e.g., publication year) that are invariant within a study and aggregated baseline covariates (e.g., mean age) that differ for each participant but are measured before randomization within a study. However, these methods have several limitations in adjusting for post-randomization variables. Although post-randomization variables share a handful of similarities with baseline covariates, they differ in several aspects. First, baseline covariates can be aggregated at the study level presumably because they are assumed to be balanced by the randomization, while post-randomization variables are not balanced across arms within a study and are commonly aggregated at the arm level. Second, post-randomization variables may interact dynamically with the primary outcome. Third, unlike baseline covariates, post-randomization variables are themselves often important outcomes under investigation. In light of these differences, we propose a Bayesian joint meta-regression approach adjusting for post-randomization variables. The proposed method simultaneously estimates the treatment effect on the primary outcome and on the post-randomization variables. It takes into consideration both between- and within-study variability in post-randomization variables. Studies with missing data in either the primary outcome or the post-randomization variables are included in the joint model to improve estimation. Our method is evaluated by simulations and a real meta-analysis of major depression disorder treatments.     

Dynamics of human populations

This study expands on earlier findings of racial/ethnic and education–allostatic load associations by assessing whether racial/ethnic differences in allostatic load persist across all levels of educational attainment. This study used data from four recent waves of the National Health and Nutrition Survey (NHANES). Results from this study suggest that allostatic load differs significantly by race/ethnicity and educational attainment overall, but that the race/ethnicity association is not consistent across education level. Analysis of interactions and education-stratified models suggest that allostatic load levels do not differ by race/ethnicity for individuals with low education; rather, the largest allostatic load differentials for Mexican Americans (p < .01) and non-Hispanic blacks (p < .001) are observed for individuals with a college degree or more. These findings add to the growing evidence that differences in socioeconomic opportunities by race/ethnicity are likely a consequence of differential returns to education, which contribute to higher stress burdens among minorities compared to non-Hispanic whites.     

Persistence in body mass index in a recent cohort of US children

While childhood obesity has become a significant public health concern over the last few decades, and underweight children continue to be a concern, knowledge pertaining to the origins of or persistence in childhood anthropometric measures is incomplete. Here, we utilize several nonparametric metrics to assess the evolution of weight and body mass index (BMI) across the entire distribution during early childhood. We find that movements within the distribution of weight – both upward and downward – are quite high prior to primary school and then decline noticeably. For BMI, we find that movements within the distribution – both upward and downward – are highest at the start of kindergarten and at the start of middle school. However, there are important sources of heterogeneity, including race, gender, and age that should prove insightful to researchers and policymakers. For instance, comparing males versus females who are initially in the bottom quartile of the distribution of BMI, we find that males have a higher probability of moving up at least 10 percentile points between kindergarten and eighth grade (53% versus 50%). Comparisons among racial groups indicate that whites who are initially in the top quartile of the distribution of BMI have a higher probability of moving down at least 10 percentile points between kindergarten and eighth grade than blacks and Hispanics (46% versus 37% and 40%, respectively).     

Height, health, and income in the US, 1984–2005

Height has been associated with better physical health when outcomes such as diabetes, heart disease, and obesity are considered, yet stature is rarely used in predicting comorbidities or as a proxy for physical health when analyzing outcomes such as income. Since height is a more exogenous measure than variables likely to be affected by lifestyle changes, such as obesity, observing labor market outcomes based on height may be revealing. In addition, gender and racial differences must be taken into account when analyzing the effects of height on physical health and labor market outcomes. This study utilizes the 1984--2005 samples of the Behavioral Risk Factor Surveillance System in estimating trends in height over time by gender and race, and in analyzing the relationship between height and physical health and labor market outcomes in the United States. Trends show that height has not changed substantially at a time when physical health, as indicated by the incidence of obesity, Type II diabetes, and cholesterol, has deteriorated, and earnings disparities across racial gaps persist. Results at mean values for males indicate that being 10cm taller is associated with a 14-47% increase in obesity, an 8-13% reduction in cholesterol prevalence, and a $1874-2306 income premium. For females, results indicate that being 10cm taller is associated with an 8-18% reduction in cholesterol, a 14% reduction in diabetes for white females, and an $891-2243 earnings premium.     

Bodyweight and human capital development: Assessing the impact of obesity on socioemotional skills during childhood in Chile

This article analyzes the effect of bodyweight on socioemotional skills for children aged two to 12 years in Chile. Using an instrumental variable approach and a representative survey, we show that both BMI and obesity are causality related to children’s socioemotional development, even after assuming that our instrument is imperfect. Although we did not find significant differences between boys and girls, we do identify heterogeneous effects by age: the weight penalty for girls starts earlier than for boys. Our findings suggest that early interventions for childhood obesity not only might generate positive impacts on children’s health, but also a greater accumulation of non-cognitive human capital in the future.     

Gender‐ethnic Disparity in BMI and Waist Circumference Distribution Shifts in US Adults

While obesity has been increasing in the United States, little is known about the variation in recent BMI and waist circumference (WC) distribution shifts across socio‐demographic groups. We assessed shifts in BMI and WC distributions and compared between‐group differences over the past decade, and projected future BMI and WC distributions and prevalence of obesity and central obesity using National Health and Nutrition Examination Survey (NHANES) 1988–1994 and 1999–2004 data. BMI/WC distributional shifts overall and in percentiles were compared across groups. Average yearly shift was calculated and used for projecting future distributions and prevalence. Both BMI and WC increased more in their uppermost percentile distribution, though BMI shift declined toward the uppermost percentiles among women. Heavier Americans gained more adiposity over the past decade. Ethnic (non‐Hispanic (NH) white vs. black) disparities in mean BMI and WC became wider. Over the survey period, mean BMI increased by 1.3 units vs. 1.8 units among men and women, whereas WC, by 4.2 cm vs. 4.8 cm. Young adults had the largest increase. Shift in women's WC was stable between the 25th and 75th percentiles, but gained pace at higher WC, while women's BMI and men's BMI and WC shifts increased linearly. NH black women had the largest shifts and would have central obesity and obesity prevalence of 90.8 and 70.7% by 2020. Shifts in BMI and WC distribution varied across age‐, gender‐, and ethnic groups. Future rise in the obesity and central obesity prevalence rates are expected, but would vary by demographic groups.     

Association of Household and Community Socioeconomic Position and Urbanicity with Underweight and Overweight among Women in Pakistan

Background

Similar to other developing countries, Pakistan is going through a rapid nutrition transition where shift from underweight to overweight and obesity is occurring. In this paper, we report on the relationship of household socioeconomic position (SEP), community SEP and urbanicity with under- and over-weight categories of BMI among Pakistani women.

Methods

We analyzed data on 4,767 women ages 15-49 years enrolled in a nationally representative Pakistan Demographic Health Survey (PDHS) conducted in 2012-13 that employed a multistage, stratified cluster sampling design. We assessed the association of urbanicity, household and community SEP derived from household assets and utilities, with categories of body mass index (BMI) using multinomial regression analysis where normal weight (BMI 18.6-22.5) was the reference category.

Results

Thirteen percent of women were underweight (BMI <18.5), 15% pre-overweight (BMI: 22.6-24.9), 25% overweight (BMI: 25.0–29.9) and 14% were obese (BMI≥30). Pre-overweight, overweight and obesity among women increased across household wealth quintiles (HWQs) in a graded fashion whereas there was no significant difference in underweight by household wealth. Women in urban areas were more likely to be obese. There was a pronounced increase in adjusted odds ratios (aORs) for overweight/obesity across HWQs within urban areas compared to rural areas. There was a steeper gradient in aORs for obesity from 1st to 5th HWQs in high income communities compared to the middle- and low income communities. In community-level analyses, communities in urban areas were more likely to have higher levels of obesity while in rural areas, especially in Sindh, more communities were more likely to have a higher level of underweight.

Conclusion

A shift to higher overweight and obesity than underweight in Pakistan is associated with high household and community wealth as well as living in urban areas. Clustering of obesity and underweight in distinct communities afford opportunity for tailored intervention programs.     

Determinants of resting energy expenditure in obese and non-obese children and adolescents

Resting energy expenditure (REE) is the largest component of total daily energy expenditure. Objectives of this study were to examine whether differences in REE exist after obesity develops in a group of children and adolescents, and to determine the effects of body composition, gender, age, pubertal development and parental obesity on REE. In 116 Caucasian children and adolescents (57 obese and 59 non-obese), aged 7.8 to 16.6 years, REE was assessed by open-circuit indirect calorimetry and different anthropometric variables and bioelectrical impedance were obtained (weight, height, skinfold thicknesses, waist and hip circumferences). Anthropometric indices and body compartments were calculated: the body mass index, surface area (SA), fat-free mass (FFM), fat-mass (FM) and percentage of FM. Differences between obese and non-obese subjects were tested and stepwise multiple regression analysis was performed with REE as dependent variable. Results show that REE was significantly higher in obese than in non-obese children and adolescents but REE/FFM ratio was not significantly different between these groups. In the non-obese group, FFM explained 73.1% of the variability in REE and gender, age and SA added 3.8%, 2.6%, and 2.6% to it, respectively. In the obese group, FFM was also the most powerful predictor of REE with 72.3%, followed by waist circumference and age with 2.5% and 2.1%, respectively. These results show that REE differences between obese and lean children do not seem to justify the maintenance of obesity. The main determinant of REE is FFM in both groups. No significant contribution of FM, pubertal development or parental obesity in REE was found in children and adolescents.     

Educational differences in obesity in the United States: a closer look at the trends

Both body weight and educational attainment have risen in the United States. Empirical evidence regarding educational differences in obesity (BMI ≥30) is inconsistent. According to some widely cited claims, these differences have declined since the 1970s, and the most educated have experienced the greatest gain in obesity. Prior research was limited in grouping college graduates with nongraduates, combining men and women in the same analysis, and using self-reported rather than measured anthropometric information. Using the National Health and Nutrition Examination Surveys (NHANES), we address these issues and examine changing educational differences in obesity from 1971-1980 to 1999-2006 for non-Hispanic whites and blacks in two separate age groups (25-44 vs. 45-64 years). We find that (i) obesity differentials by education have remained largely stable, (ii) compared with college graduates, less educated whites and younger black women continue to be more likely to be obese, (iii) but the differentials are larger for women than men, and weak or nonexistent among black men and older black women. There are exceptions to the overall trend. The obesity gap has widened between the two groups of college-educated younger women, but disappeared between the least and most educated younger white men. Thus, the increase in obesity was similar for most educational groups, but significantly greater for younger women with some college and smaller for younger white men without a high-school degree. Lumping together the two distinct college groups has biased previous estimates of educational differences in obesity.     

Individual and Aggregate Years‐of‐life‐lost Associated With Overweight and Obesity

This study presents nationally representative estimates of individual and aggregate years‐of‐life‐lost (YLLs) associated with overweight and three categories of obesity separately by age, race, smoking status, and gender strata. Using proportional hazards analysis and data from the National Health Interview Survey (NHIS) Linked Mortality Files, we estimated life expectancies for each BMI strata and quantified YLLs by comparing differences between each strata and the normal BMI reference group. Our results provide further evidence that overweight and mild obesity are not associated with a reduction in life expectancy. However, higher BMI categories are associated with lower expected survival. In aggregate, excess BMI is responsible for ～95 million YLLs. White females account for more than two‐thirds of the aggregate YLLs. Unless something is done to reduce the rising prevalence of those with BMIs >35, or to mitigate the impact of obesity or its correlates on YLLs, expected life expectancy for US adults may decrease in the future.     

Race and the inheritance of low birth weight

This paper uses intergenerational data from the Panel Study of Income Dynamics (PSID) to address the black-white difference in propensities toward low birth weight (LBW). We determine that socioeconomic conditions account for some variation in low birth weight across race. Further, while race differences in the risk of low birth weight cannot be explained entirely, we find that the inheritance of parental birth weight status dramatically reduces the black-white gap in low birth weight. Intergenerational legacies of poor infant health explain the largest share of racial disparities in filial birth weight. We then try to assess whether this intergenerational transmission of low birth weight is indeed genetic by using grandparent-fixed effects models to factor out, to a great extent, family socioeconomic circumstances. We find that even within this framework, both father's and mother's birth weight status have an important impact on filial outcomes. However, the degree of inheritance is weaker for African Americans than for other races. Finally, we theorize that the importance of paternal birth weight status implies a genetic association that does not work through the uterine environment but rather through the fetus itself.     

Gender,Race, and Obesity‐Related Quality of Life at Extreme Levels of Obesity

Objective: Research investigating obesity‐related quality of life (QOL) has shown that at increasing levels of overweight, individuals report more impaired QOL. Further, some research has indicated that white women suffer more impairment than men and African Americans. The current study sought to expand the existing literature by investigating an extreme subsample of the obese population. It was expected that participants in the current study would report more impaired obesity‐related QOL than in previous research conducted with less obese individuals. It was also hypothesized that race and gender groups would differ in obesity‐related QOL and that the relationship between degree of overweight and QOL would not be consistent across race and gender groups. Research Methods and Procedures: Impact of Weight on Quality of Life Questionnaire‐Lite Version data were collected from 512 individuals seeking gastric bypass surgery (mean BMI = 53.3) Results: Results confirmed the study hypotheses. In general, white women reported the most QOL impairment, despite having significantly lower BMI than other race/gender groups. Compared with previous studies, the observed relationships between BMI and QOL were somewhat attenuated. Discussion: Various domains of QOL may be differentially affected by degree of obesity; these relationships are not homogeneous throughout the obese population.     

Racial/ethnic disparities in infant mortality: the role of behavioral factors

Using the National Maternal and Infant Health Survey 1988 (NMIHS), a nationally representative sample of mothers, we investigate the role of behavioral factors in explaining racial/ethnic disparities in infant mortality. In particular, we focus on the following variables: weight gain during pregnancy, prenatal care utilization, exercise, vitamin use, and substance use during pregnancy. These analyses are conducted by modeling both time of death (neonatal vs. postneonatal) and cause of death (infections, perinatal complications, delivery complications, congenital malformations, SIDS, other causes) outcomes. Our results suggest that behavioral factors are partially responsible for observed race/ethnic differentials in infant mortality, but are not as important as sociostructural determinants such as SES.     

Genetic and environmental effects on complex traits in mice

The interaction between genotype and environment is recognized as an important source of experimental variation when complex traits are measured in the mouse, but the magnitude of that interaction has not often been measured. From a study of 2448 genetically heterogeneous mice, we report the heritability of 88 complex traits that include models of human disease (asthma, type 2 diabetes mellitus, obesity, and anxiety) as well as immunological, biochemical, and hematological phenotypes. We show that environmental and physiological covariates are involved in an unexpectedly large number of significant interactions with genetic background. The 15 covariates we examined have a significant effect on behavioral and physiological tests, although they rarely explain >10% of the variation. We found that interaction effects are more frequent and larger than the main effects: half of the interactions explained >20% of the variance and in nine cases exceeded 50%. Our results indicate that assays of gene function using mouse models should take into account interactions between gene and environment.     

Ethnicity and fertility in Nigeria

Using a sample of Hausa-Fulani, Yoruba, Ibo, and all other women from the 1990 Nigerian Demographic and Health Survey, this study examines ethnic fertility differentials in Nigeria within the context of the social characteristics and cultural hypotheses. Among all women, we find the net fertility of Hausa-Fulani women to be lower than that of Other women; with no statistically significant difference in the net fertility of Ibo, Yourba, and Other women. But, among currently married women, we find the net fertility of Hausa-Fulani and Yoruba women to be lower than that of Other women, while the net fertility of Ibo women is higher than that of Other women. Overall, the findings of this study are more consistent with the cultural hypothesis, because statistically significant fertility differentials by ethnicity remain, even after controlling for selected socioeconomic and demographic variables.     

Rates of climatic niche evolution are correlated with species richness in a large and ecologically diverse radiation of songbirds

By employing a recently inferred phylogeny and museum occurrence records, we examine the relationship of ecological niche evolution to diversification in the largest family of songbirds, the tanagers (Thraupidae). We test whether differences in species numbers in the major clades of tanagers can be explained by differences in rate of climatic niche evolution. We develop a methodological pipeline to process and filter occurrence records. We find that, of the ecological variables examined, clade richness is higher in clades with higher climatic niche rate, and that this rate is also greater for clades that occupy a greater extent of climatic space. Additionally, we find that more speciose clades contain species with narrower niche breadths, suggesting that clades in which species are more successful at diversifying across climatic gradients have greater potential for speciation or are more buffered from the risk of extinction.     

Differences in geriatric anthropometric data between DXA-based subject-specific estimates and non-age-specific traditional regression models

Age, obesity, and gender can have a significant impact on the anthropometrics of adults aged 65 and older. The aim of this study was to investigate differences in body segment parameters derived using two methods: (1) a dual-energy x-ray absorptiometry (DXA) subject-specific method (Chambers et al., 2010) and (2) traditional regression models (de Leva, 1996). The impact of aging, gender, and obesity on the potential differences between these methods was examined. Eighty-three healthy older adults were recruited for participation. Participants underwent a whole-body DXA scan (Hologic QDR 1000/W). Mass, length, center of mass, and radius of gyration were determined for each segment. In addition, traditional regressions were used to estimate these parameters (de Leva, 1996). A mixed linear regression model was performed (α = 0.05). Method type was significant in every variable of interest except forearm segment mass. The obesity and gender differences that we observed translate into differences associated with using traditional regressions to predict anthropometric variables in an aging population. Our data point to a need to consider age, obesity, and gender when utilizing anthropometric data sets and to develop regression models that accurately predict body segment parameters in the geriatric population, considering gender and obesity.