The nature of environmental influences on weight and obesity: a behavior genetic analysis

Laparoscopic Sleeve Gastrectomy in Monozygotic Twins: Report of the First Case

Obesity is an epidemic disease that is believed to link to other pathologies as well as life-threatening cardiovascular pathology. Here we report a case of monozygotic twins who successfully lost weight following laparoscopic sleeve gastrectomy at the end of the 18-month follow-up period. We aimed to determine the factors affecting the weight loss outcome after sleeve gastrectomy in monozygotic twins. The twins' initial BMIs were 37.1 kg/m2 and 40.2 kg/m2, respectively. Twin A's excess weight loss was 48.4%, 61.3%, 80.6%, 96.8%, and 112.9% at three, six, nine, 12 and 18 months, while Twin B's in the third, sixth, ninth, 12th and 18th months was 23.1%, 41%, 51.3%, 61.5% and 71.8%. On the third, sixth, ninth, 12th, and 18th months of Twin A, the total weight loss was 15.8%, 20%, 26.3%, 31.6%, and 36.8%. In Twin B in the third, sixth, ninth, 12th, and 18th months, it was 8.7%, 15.5%, 19.4%, 23.3%, and 27.2%. When the twins were compared in terms of excess weight loss and total weight loss at 18 months, Twin A was more successful than Twin B. Especially at this point, Twin B's having a child (three years old) at a young age, her low compliance with the recommendations in the post-operative period and her difficulty in changing her lifestyle, environmental factors are as important as hereditary factors in achieving weight loss and a healthy body mass index (BMI) range.

A review on the beneficial effects of bariatric surgery in the management of obesity

INTRODUCTION

Obesity is a chronic disease with a complex interplay of multiple factors such as genetic, metabolic, behavioral, and environmental factors. The management of obesity includes; lifestyle modification, psychological therapy, pharmacological therapy, and bariatric surgery. To date, bariatric surgery is the most effective treatment for obesity by offering a long-term reduction in weight, remission of obesity-related complications, and improving quality of life. However, bariatric surgery is not equally effective in all patients. Thus, if we can predict who would benefit most, it will improve the risk versus benefit ratio of having surgery.

AREAS COVERED

In this narrative review, we explore the question on who will benefit the most from bariatric surgery by examining the recent evidence in the literature. In addition, we investigate the predisposing predictors of bariatric surgery response. Finally, we offer the best strategies in the clinic to explain the potential benefits of bariatric surgery to patients.

EXPERT OPINION

Bariatric surgery is an effective obesity management approach. Despite its efficacy, considerable variation of individual response exists. Thus, it is important to recognize patients that will benefit most, but at present very few predictors are available which can be clinically useful.

All in the Family: Child and Adolescent Weight Loss Surgery in the Context of Parental Weight Loss Surgery

Background: Bariatric surgery is the most effective current treatment option for patients with severe obesity. More children and adolescents are having surgery, many whose parents have also had surgery. The current study examines whether parental surgery status moderates the association between perceived social support, emotional eating, food addiction and weight loss following surgery, with those whose parents have had surgery evidencing a stronger relationship between the psychosocial factors and weight loss as compared to their peers. Methods: Participants were 228 children and adolescents undergoing sleeve gastrectomy between 2014 and 2019 at one institution. Children and adolescents completed self-report measures of perceived family social support, emotional eating, and food addiction at their pre-surgical psychological evaluation. Change in body mass index (BMI) from pre-surgery to 3, 6, and 12 months post-surgery was assessed at follow-up clinic visits. Parents reported their surgical status as having had surgery or not. Results: There were no differences in perceived family support, emotional eating, or food addiction symptoms between those whose parents had bariatric surgery and those whose parents did not. There were some moderating effects of parent surgery status on the relationship between social support, emotional eating/food addiction, and weight loss following surgery. Specifically, at 3 months post-surgery, higher change in BMI was associated with lower perceived family support only in those whose parents had not had surgery. More pre-surgical food addiction symptoms were associated with greater weight loss at 3 months for those whose parents had not had surgery, whereas this finding was true only for those whose parents had surgery at 12 months post-surgery. Conclusions: Children and adolescents whose parents have had bariatric surgery may have unique associations of psychosocial factors and weight loss. More research is needed to determine mechanisms of these relationships.

Parenting Styles, Food Parenting Practices and Dietary Intakes of Preschoolers

Previous evidence suggests that children’s eating behaviors were largely influenced by the parent and home eating structure. This study examined the relationship between parenting styles (including authoritative, authoritarian, indulgent, and uninvolved), food parenting practices (within Structure, Coercive Control, and Autonomy Support constructs) and dietary intakes of preschoolers. Children aged 3–5 years and their parents were recruited from preschools/daycare centers and parents completed the surveys (n = 166). Dietary intakes were collected using the Harvard Service Food Frequency Questionnaire (HSFFQ), parenting style was assessed using the Parenting Dimensions Inventory-Short Version (PDI-S), and food parenting practices were measured using Comprehensive Home Environment Survey (CHES). The results showed that food parenting practices had a higher number of specific significant findings on children’s nutrient and food group intakes than parenting styles. Correlation analyses showed positive parenting practices within Structure were significantly related to healthier children’s intakes (e.g., vegetables, iron, and folate) and less unhealthy dietary intakes (e.g., sweets and total fats). Regression models show that children with authoritative parents consumed more fruits compared to children with authoritarian parents and indulgent parents. The results addressed the importance of parental influences for preschoolers’ healthy dietary intakes, which suggested that future interventions and educational programs could enhance parenting practices to impact child diet.

Shared Dynamics of Food Decision-Making in Mother-Child Dyads

This study explored risk parameters of obesity in food decision-making in mother-child dyads. We tested 45 children between 8–12 years and their biological mothers to measure the decision weights of food health attributes, the decision weights of food taste attributes, self-regulated food decisions, and self-reported self-control scores. Maternal body mass index (BMI), and children's BMI-percentiles-for-age were also measured. We found a positive correlation between children's and their mothers' decision weights of taste attributes in food decision-making. We also found a positive correlation between children's BMI %iles and their mothers' BMIs. Children with overweight/obesity demonstrated lower correlations between health and taste ratings and a lower percentage of self-regulated food decisions (i.e., resisting to eat tasty but unhealthy foods or choosing to eat not-tasty but healthy foods) than children with healthy weight. Our findings suggested that the decision weights of taste attributes and weight status shared similar patterns in mother-child dyads. Also, the findings suggested that establishing dynamics of unhealthy food-decision making may increase the risk of childhood obesity. Helping children to develop the dynamics of healthy food-decision making by increasing the importance of health while decreasing the importance of taste may promote resilience to susceptibility to unhealthy eating and weight gain.

The medical care costs of obesity and severe obesity in youth: An instrumental variables approach

This paper is the first to use the method of instrumental variables to estimate the impact of obesity and severe obesity in youth. on U.S. medical care costs. We examine data from the Medical Expenditure Panel Survey for 2001-2015 and instrument for child BMI using the BMI of the child's biological mother. Instrumental variables estimates indicate that obesity in youth raises annual medical care costs by $907 (in 2015 dollars) or 92%, which is considerably higher than previous estimates of the association of youth obesity with medical costs. We find that obesity in youth significantly raises costs in all major categories of medical care: outpatient doctor visits, inpatient hospital stays, and prescription drugs. The costs of youth obesity are borne almost entirely by third-party payers, which is consistent with substantial externalities of youth obesity, which in turn represents an economic rationale for government intervention.

Heterogeneous effects of obesity on mental health: Evidence from Mexico

Obesity can spread more easily if it is not perceived negatively. This issue may be more pronounced among the poor, a conjecture that we test in this paper. We start with general evidence on the concave relationship between income and obesity, both across countries and within Mexico, a country characterized by very unequal development levels and the highest obesity rate in the world. We suggest a general model that explains this stylized fact from a simple necessary condition, namely, the complementarity between nonfood consumption and health concerns. Then, we test the direct effect of overweight on mental health among Mexican women. We find a positive effect of obesity in the low consumption group and a depressing effect among the rich. This result is robust to the inclusion of a range of confounders (childhood conditions, lifestyle variables, food expenditure, and household shocks) and after instrumenting individual fatness by the variation in genetic predisposition. The complementarity between living standards and weight concerns may reflect different norms, different labor market penalties, or simply different returns to healthy time across the social spectrum.

The health care costs of childhood obesity in Australia: An instrumental variables approach

The effect of childhood obesity on medical costs incurred by the Australian Government is estimated using five waves of panel data from the Longitudinal Study of Australian Children, which is linked to public health insurance administrative records from Medicare Australia. Instrumental variables estimators are used to address concerns about measurement error and selection bias. The additional annual medical costs due to overweight and obesity among 6 to 13 year olds is about $43 million (in 2015 AUD). This is driven by a higher utilisation of general practitioner and specialist doctors. The results suggest that the economic consequences of childhood obesity are much larger than previously estimated.

Linking Positive Affect to Blood Lipids: A Cultural Perspective

Higher levels of positive affect have been associated with better physical health. While positive affect is seen as highly desirable among Westerners, East Asians tend to deemphasize positive affect. Using large probability samples of Japanese and U.S. adult populations, the present study examined the relations of positive affect with serum lipid profiles, known to be strongly predictive of risk for cardiovascular disease, and tested whether their associations depend on cultural contexts. As predicted, positive affect was associated with healthier lipid profiles for Americans but not for Japanese. Further analyses showed that this cultural moderation was mediated by body mass index. This study highlights the role of culture in the link between positive emotions and key biological risk factors of cardiovascular disease.

Obesity and the labor market: A fresh look at the weight penalty

This paper applies semiparametric regression models to shed light on the relationship between body weight and labor market outcomes in Germany. We find conclusive evidence that these relationships are poorly described by linear or quadratic OLS specifications. Women's wages and employment probabilities do not follow a linear relationship and are highest at a body weight far below the clinical threshold of obesity. This indicates that looks, rather than health, is the driving force behind the adverse labor market outcomes to which overweight women are subject. Further support is lent to this notion by the fact that wage penalties for overweight and obese women are only observable in white-collar occupations. On the other hand, bigger appears to be better in the case of men, for whom employment prospects increase with weight, albeit with diminishing returns. However, underweight men in blue-collar jobs earn lower wages because they lack the muscular strength required in such occupations.

The significance of overweight and obesity for individual health behaviour: An economic analysis based on the Swedish surveys of living conditions 1980—81, 1988—89, and 1996—97

Aims: The aim of the study was to examine whether being overweight (25≤BMI<30) or obese (BMI≥30) affect subsequent individual health behaviour, applying the framework of the individual-as-producer-of-health model. Methods: A set of panel data for 3,693 individuals interviewed repeatedly in 1980—81, 1988—89, and 1996—97 was created from the Swedish population-based biannual survey of living conditions. Self-assessed health was chosen as indicator of individual health capital and physical exercise as indicator of individual health investment. Results: (a) Men and women who suffered from obesity invested significantly less in their health in terms of physical exercise and reported significantly lower self-assessed health than the general male and female population, respectively. (b) Men who suffered from overweight invested less in their health and reported significantly lower self-assessed health than the general population, whereas women who were overweight — but not obese — did not differ from the general population. (c) Men and women who went from being obese to being overweight reported self-assessed health levels that did not differ from the general male and female population, respectively, but exercised less than men and women in general. Conclusions: The results imply (a) that the individual weight history must be taken into account in studies of the effect of obesity and overweight on health and health-related behaviour and (b) that men and women differ concerning the impact of obesity and overweight on health and health investments.

The impact of family members on weight loss after sleeve gastrectomy

BACKGROUND

Weight loss after laparoscopic sleeve gastrectomy (LSG) is multifactorial. Postoperative compliance with appropriate dietary guidance may be affected by psychosocial factors and may influence the success of surgery.

OBJECTIVE

To evaluate the effect of LSG in siblings compared to case-matched controls.

SETTING

University hospital.

METHODS

Siblings who had undergone LSG were compared with controls case-matched by age, sex, and body mass index. The percentage excess weight loss (%EWL) was calculated at 3, 6, and 12 months postoperatively.

RESULTS

We had 32 siblings, of which 4 were lost to follow-up. Thus, 28 (87.5%) siblings completed 1 year of follow-up and were included in the study. In the family group, the %EWL was 72.7±15.0% at 1 year while in the control group the mean %EWL was 62.1±21.4%. Patients in the family group had significantly greater weight loss. Within the family group, the outcomes of family order had no statistically significant difference in weight loss between the first family member who had undergone LSG and subsequent family members. In addition, family members who had resided together in the same home had no advantage over those who resided separately.

CONCLUSION

Genetic and environmental factors may have great influence on outcomes after bariatric surgery.

Perceived weight discrimination, childhood maltreatment, and weight gain in U.S. adults with overweight/obesity

OBJECTIVE

Perceived weight discrimination and childhood maltreatment have been independently associated with physical and mental health issues, as well as weight gain. It is not known, however, whether childhood maltreatment modifies the relationship between perceived weight discrimination and weight changes.

METHODS

This study examined the relationship between perceived weight discrimination, childhood maltreatment, and changes in body mass index (BMI) over 3 years in 21,357 men and women with overweight and obesity from Wave 1 and Wave 2 surveys of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC).

RESULTS

Reporting childhood maltreatment, regardless of the specific form of maltreatment, was associated with a significantly greater likelihood of perceived weight discrimination in women. Perceived weight discrimination was associated with a significantly greater increase in BMI in both genders. Among all women with perceived weight discrimination, those who also reported having experienced childhood maltreatment had significantly less BMI increase compared to those reporting not having experienced childhood maltreatment.

CONCLUSIONS

Perceived weight discrimination may foster weight gain rather than encouraging weight loss in individuals with overweight/obesity and should be addressed in prevention efforts and clinical settings. Childhood maltreatment may perhaps sensitize individuals to subsequent stressors and increase vulnerability to perceived weight discrimination, particularly in women.

Shared and unique mechanisms underlying binge eating disorder and addictive disorders

Scientific interest in "food addiction" is growing, but the topic remains controversial. One critique of "food addiction" is its high degree of phenotypic overlap with binge eating disorder (BED). In order to examine associations between problematic eating behaviors, such as binge eating and "food addiction," we propose the need to move past examining similarities and differences in symptomology. Instead, focusing on relevant mechanisms may more effectively determine whether "food addiction" contributes to disordered eating behavior for some individuals. This paper reviews the evidence for mechanisms that are shared (i.e., reward dysfunction, impulsivity) and unique for addiction (i.e., withdrawal, tolerance) and eating disorder (i.e., dietary restraint, shape/weight concern) frameworks. This review will provide a guiding framework to outline future areas of research needed to evaluate the validity of the "food addiction" model and to understand its potential contribution to disordered eating.

The effects of smoking on obesity: evidence from Indonesian panel data

Background

It has been known that smoking is negatively related to weight-related outcomes. However, it has been difficult to determine whether the relationship is causal, and if so, how strong it is. We attempted to estimate the approximately causal effects of smoking on weight, body mass index (BMI), and obesity.

Methods

The Indonesian Family Life Survey provided a sample of over 9000 men aged 15–55 years—each of them was observed in 1993, 1997, 2000 and 2007. The preferred method was a fixed effects model; that is, we related changes in smoking status or smoking intensity to changes in weight-related outcomes, while controlling for time-varying covariates. We also compared these results to those estimated by ordinary least squares and assessed the importance of controlling for time invariant individual heterogeneity.

Results

Although the effects of smoking were precisely estimated in a statistical sense, their size was minuscule: a quitter would gain weight by at most 1 kg, or a smoker would lose weight by the same amount. The results were similar for BMI and obesity. When we did not control for time invariant individual heterogeneity, the size of the relationship was overestimated at least three times.

Conclusions

Smoking exerted little influence on weight, and it was important to control for bias stemming from time invariant individual heterogeneity.

Savings in Medical Expenditures Associated with Reductions in Body Mass Index Among US Adults with Obesity, by Diabetes Status

BACKGROUND

The prevalence of obesity has more than doubled in the USA in the past 30 years. Obesity is a significant risk factor for diabetes, cardiovascular disease, and other clinically significant co-morbidities. This paper estimates the medical care cost savings that can be achieved from a given amount of weight loss by people with different starting values of body mass index (BMI), for those with and without diabetes. This information is an important input into analyses of the cost effectiveness of obesity treatments and prevention programs.

METHODS

Two-part models of instrumental variables were estimated using data from the Medical Expenditure Panel Survey (MEPS) for 2000-2010. Models were estimated for all adults as well as separately for those with and without diabetes. We calculated the causal impact of changes in BMI on medical care expenditures, cost savings for specific changes in BMI (5, 10, 15, and 20 %) from starting BMI levels ranging from 30 to 45 kg/m(2), as well as the total excess medical care expenditures caused by obesity.

RESULTS

In the USA, adult obesity raised annual medical care costs by $US3,508 per obese individual, for a nationwide total of $US315.8 billion (year 2010 values). However, the relationship of medical care costs over BMI is J-shaped; costs rise exponentially in the range of class 2 and 3 obesity (BMI ≥35). The heavier the obese individual, the greater the reduction in medical care costs associated with a given percent reduction in BMI. Medical care expenditures are higher, and rise more with BMI, among individuals with diabetes than among those without diabetes.

CONCLUSIONS

The savings from a given percent reduction in BMI are greater the heavier the obese individual, and are greater for those with diabetes than for those without diabetes. The results provide health insurers, employers, government agencies, and health economists with accurate estimates of the change in medical care expenditures resulting from weight loss, which is important information for calculating the cost effectiveness of interventions to prevent and treat obesity.

Body size, skills, and income: evidence from 150,000 teenage siblings

We provide new evidence on the long-run labor market penalty of teenage overweight and obesity using unique and large-scale data on 150,000 male siblings from the Swedish military enlistment. Our empirical analysis provides four important results. First, we provide the first evidence of a large adult male labor market penalty for being overweight or obese as a teenager. Second, we replicate this result using data from the United States and the United Kingdom. Third, we note a strikingly strong within-family relationship between body size and cognitive skills/noncognitive skills. Fourth, a large part of the estimated body-size penalty reflects lower skill acquisition among overweight and obese teenagers. Taken together, these results reinforce the importance of policy combating early-life obesity in order to reduce healthcare expenditures as well as poverty and inequalities later in life.

Gender differences in the impact of stressful life events on changes in body mass index

OBJECTIVE

The positive association between stress and weight has been consistently demonstrated, particularly in women. The effect of stress on changes in weight, however, is less clear.

METHODS

A total of 33,425 participants in Wave 1 and Wave 2 surveys of the National Epidemiologic Survey on Alcohol and Related Condition (NESARC) were included in this study. The study examined the relationship between stressful life events during the 12months prior to the Wave 2 interview and changes in body mass index (BMI) between Wave 1 and Wave 2 interviews.

RESULTS

Women reported significantly greater increases in BMI than men. Stressful life events, particularly job-related changes, legal problems, and death of family or friends, were associated significantly with increases in BMI among women but not men.

CONCLUSIONS

In a nationally representative sample, stressful life events were associated with greater weight gain in women. Prevention of weight gain in women should focus on the behavioral and physiological mechanisms underlying female-specific effects of stressful life events on weight gain.

Differential maternal feeding practices, eating self-regulation, and adiposity in young twins

OBJECTIVE

Restrictive feeding is associated with childhood obesity; however, this could be due to other factors that drive children to overeat and parents to restrict (eg, child genetics). Using a twin design to better control for confounders, we tested differences in restrictive feeding within families in relation to differences in twins' self-regulatory eating and weight status.

METHODS

Sixty-four same-gender twin pairs (4-7 years old) were studied with their mothers. Child caloric compensation ability (COMPX% index) was assessed by using a laboratory-based protocol. The Child Feeding Questionnaire assessed mothers' self-reported feeding styles toward each twin. Child BMI (kg/m(2)) and BMI z score were calculated by using measured weight and height; percent body fat and waist circumference were also assessed. Partial correlations examined within-twin pair differences in Child Feeding Questionnaire subscales in relation to within-twin pair differences in anthropometry and caloric compensation (COMPX%).

RESULTS

Differences in maternal restriction were significantly associated with within-pair differences in child COMPX% and BMI z score. Mothers reported more restriction toward the heavier and more poorly compensating twin. Additionally, within-pair differences in parental pressure to eat were associated with significant differences in BMI z score, percent body fat, and waist circumference. Mothers were more pressuring toward the lighter twin.

CONCLUSIONS

Mothers vary in their feeding practices, even among same-gender twin pairs, which might influence differences in adiposity. Future research needs to elucidate cause-and-effect and intervention implications regarding parental restriction and pressure-to-eat prompts.

Childhood Maltreatment in Extremely Obese Male and Female Bariatric Surgery Candidates**

OBJECTIVE

To examine rates of self-reported childhood maltreatment in extremely obese bariatric surgery candidates and to explore associations with sex, eating disorder features, and psychological functioning.

RESEARCH METHODS AND PROCEDURES

Three hundred forty (58 men and 282 women) extremely obese consecutive candidates for gastric bypass surgery completed a questionnaire battery. The Childhood Trauma Questionnaire was given to assess childhood maltreatment.

RESULTS

Overall, 69% of patients self-reported childhood maltreatment: 46% reported emotional abuse, 29% reported physical abuse, 32% reported sexual abuse, 49% reported emotional neglect, and 32% reported physical neglect. Except for higher rates of emotional abuse reported by women, different forms of maltreatment did not differ significantly by sex. Different forms of maltreatment were generally not associated with binge eating, current BMI, or eating disorder features. At the Bonferonni-corrected significance level, emotional abuse was associated with higher eating concerns and body dissatisfaction, and emotional neglect was associated with higher eating concerns. In terms of psychological functioning, at the Bonferonni-corrected level, emotional abuse and emotional neglect were associated with higher depression and lower self-esteem, and physical abuse was associated with higher depression.

DISCUSSION

Extremely obese bariatric surgery candidates reported rates of maltreatment comparable with those reported by clinical groups and roughly two to three times higher than normative community samples. Reported experiences of maltreatment differed little by sex and were generally not significantly associated with current BMI, binge eating, or eating disorder features. In contrast, maltreatment-notably emotional abuse and neglect-were significantly associated with higher depression and lower self-esteem.

Within-family variation in obesity

We use data from the Children of the National Longitudinal Survey of Youth 1979 to document the degree to which childhood obesity varies among siblings. We find considerable differences in body weight between siblings with over half of the siblings differing by more than 20 age-specific percentiles in terms of the body mass index. Even among identical twins, there is an average BMI difference of 12 percentiles. This variation is important for the use of econometric approaches that involve sibling comparisons.

Segregation Analysis of Body Mass Index in an Unselected French-Canadian Sample: The Québec Family Study

Interest in a single gene etiology for obesity, as assessed by the body mass index (BMI), has been spurred recently by reports of a putative recessive major gene for extreme values, which accounts for as much as 40% of the variance. The major gene hypothesis was evaluated here in the Québec Family Study, a random sample of 375 French-Canadian volunteer families. This report represents one component in a more complete investigation of obesity in these families. In contrast to the recent studies, a major gene hypothesis for BMI was not verified here. Although there was a major effect, it did not conform to a Mendelian pattern of transmission. A multifactorial component (i.e., polygenic and/or common environmental factors) accounted for 42% of the phenotypic variance. In addition, evidence of heterogeneity between the generations was found. The heterogeneity was traced to the major non-Mendelian component (which accounted for 0.01% of the variance in parents and over 40% in offspring) rather than to the multifactorial one. These results would suggest that a simple recessive gene mixed model may not be sufficient to explain the familial distribution of the BMI. Several factors which may have contributed to these results include temporal trends and surrogate effects such as those related to variation in body composition and energy balance components.

Obesity in Families of Extremely Obese Women

In order to assess the prevalence of obesity in families of extremely obese individuals, we conducted a mail survey of a national obesity organization. Thirty-nine percent (N=981) of the questionnaires were completed and returned. Respondents were excluded from further analysis if they were adopted, male, their gender could not be determined, provided incomplete information about their parents or their own height and weight, or were less than 22 or greater than 63 years of age. The analyses included 729 probands and their families. Both the prevalence and the extent of obesity were high in the families members. The average family members' body mass index (BMI=kg/m2) was 30, and 78% of the families studied had at least one other obese (BMI>30 kg/m2) first-degree relative (parent, sibling, or child). Although obesity was common in the families, survey respondents were generally the heaviest members of their families, having an average BMI of 47 kg/m2. Correlations among first-degree relatives were similar to those found for average weight groups, suggesting that obesity and BMI are similarly influenced by family genetic factors in this extremely obese population.

Body weight and wages: evidence from Add Health

This note uses data from the National Longitudinal Study of Adolescent Health to examine the relationship between body weight and wages. Ordinary least squares (OLS) and individual fixed effects estimates provide evidence that overweight and obese white women are paid substantially less per hour than their slimmer counterparts. Two-stage least squares (2SLS) estimation confirms this relationship, suggesting that it is not driven by time-variant unobservables.

The medical care costs of obesity: an instrumental variables approach

This paper is the first to use the method of instrumental variables (IV) to estimate the impact of obesity on medical costs in order to address the endogeneity of weight and to reduce the bias from reporting error in weight. Models are estimated using restricted-use data from the Medical Expenditure Panel Survey for 2000-2005. The IV model, which exploits genetic variation in weight as a natural experiment, yields estimates of the impact of obesity on medical costs that are considerably higher than the estimates reported in the previous literature. For example, obesity is associated with $656 higher annual medical care costs, but the IV results indicate that obesity raises annual medical costs by $2741 (in 2005 dollars). These results imply that the previous literature has underestimated the medical costs of obesity, resulting in underestimates of the economic rationale for government intervention to reduce obesity-related externalities.

Epidemiology, epigenetics and the 'Gloomy Prospect': embracing randomness in population health research and practice

Epidemiologists aim to identify modifiable causes of disease, this often being a prerequisite for the application of epidemiological findings in public health programmes, health service planning and clinical medicine. Despite successes in identifying causes, it is often claimed that there are missing additional causes for even reasonably well-understood conditions such as lung cancer and coronary heart disease. Several lines of evidence suggest that largely chance events, from the biographical down to the sub-cellular, contribute an important stochastic element to disease risk that is not epidemiologically tractable at the individual level. Epigenetic influences provide a fashionable contemporary explanation for such seemingly random processes. Chance events-such as a particular lifelong smoker living unharmed to 100 years-are averaged out at the group level. As a consequence population-level differences (for example, secular trends or differences between administrative areas) can be entirely explicable by causal factors that appear to account for only a small proportion of individual-level risk. In public health terms, a modifiable cause of the large majority of cases of a disease may have been identified, with a wild goose chase continuing in an attempt to discipline the random nature of the world with respect to which particular individuals will succumb. The quest for personalized medicine is a contemporary manifestation of this dream. An evolutionary explanation of why randomness exists in the development of organisms has long been articulated, in terms of offering a survival advantage in changing environments. Further, the basic notion that what is near-random at one level may be almost entirely predictable at a higher level is an emergent property of many systems, from particle physics to the social sciences. These considerations suggest that epidemiological approaches will remain fruitful as we enter the decade of the epigenome.

Metabolic syndrome in obese patients with binge-eating disorder in primary care clinics: a cross-sectional study

BACKGROUND

The distribution and nature of metabolic syndrome in obese patients with binge-eating disorder (BED) are largely unknown and require investigation, particularly in general internal medicine settings. The objectives of this study were to (1) examine the frequency of metabolic syndrome and (2) explore its eating- and weight-related correlates in obese patients with BED.

METHOD

This was a cross-sectional analysis of 81 consecutive treatment-seeking obese (body mass index ≥ 30 kg/m(2)) patients (21 men, 60 women) who met DSM-IV-TR research criteria for BED (either subthreshold criteria: ≥ 1 binge weekly, n = 19 or full criteria: ≥ 2 binges weekly, n = 62). Participants were from 2 primary care facilities in a large university-based medical center in an urban setting. Patients with and without metabolic syndrome were compared on demographic features and current and historical eating- and weight-related variables. Data were collected from December 2007 through March 2009.

RESULTS

Forty-three percent of patients met criteria for metabolic syndrome. A significantly higher proportion of men (66%) than women (35%) met criteria for metabolic syndrome (P = .012). Patients with versus without metabolic syndrome did not differ significantly in ethnicity or body mass index. Patients with versus without metabolic syndrome did not differ significantly in binge-eating frequency, severity of eating disorder psychopathology, or depression. Analyses of covariance controlling for gender revealed that patients without metabolic syndrome started dieting at a significantly younger age (P = .037), spent more of their adult lives dieting (P = .017), and reported more current dietary restriction (P = .018) than patients with metabolic syndrome.

CONCLUSIONS

Metabolic syndrome is common in obese patients with BED in primary care settings and is associated with fewer dieting behaviors. These findings suggest that certain lifestyle behaviors, such as increased dietary restriction, may be potential targets for intervention with metabolic syndrome.

The effect of body weight on adolescent sexual activity

Recent research suggests that overweight females suffer penalties in the labor and marriage markets, while overweight males do not. This study explores whether similar gender differences in the effect of body weight exist in what Cawley et al. (2006) labeled 'the adolescent sex market'. Drawing on data from the National Longitudinal Study of Adolescent Health, we use fixed effects and instrumental variables identification strategies to estimate the relationship between body weight and sexual activity. We find evidence that increased body weight lowers the probability that female adolescents become sexually active. In contrast, there is little evidence of a causal relationship between body weight and sexual activity for male adolescents.

Parental substance use history of overweight men and women with binge eating disorder is associated with distinct developmental trajectories and comorbid mood disorder

OBJECTIVE

To examine the significance of parental histories of substance use disorders (SUDs) in the expression of binge eating disorder (BED) and associated functioning.

METHOD

Participants were 127 overweight patients with BED assessed using diagnostic interviews. Participants were administered a structured psychiatric history interview about their parents (N = 250) and completed a battery of questionnaires assessing current and historical eating and weight variables and associated psychological functioning (depression and self-esteem).

RESULTS

Patients with BED with a parental history of SUD were significantly more likely to start binge eating before dieting, had a significantly earlier age at BED onset, and reported less time between binge eating onset and meeting diagnostic criteria for BED than did patients without a parental history of SUD. For psychiatric comorbidity, patients with BED with a parental history of SUD were significantly more likely to meet the criteria for a mood disorder. A parental history of SUD was not significantly associated with variability in current levels of binge eating, eating disorder psychopathology, or psychological functioning.

DISCUSSION

Our findings suggest that a parental history of SUD is associated with certain distinct trajectories in the development of binge eating (earlier binge onset predating dieting onset) and with elevated rates of comorbidity with mood disorders in patients with BED.

Negative weight-based attitudes in treatment-seeking obese monolingual Hispanic patients with and without binge eating disorder

OBJECTIVE

The aims of this study were to compare weight-based attitudes in obese Latino adults with and without binge eating disorder (BED) and to examine whether these attitudes are related to indices of eating disorder psychopathology and psychological functioning.

METHOD

Participants were a consecutive series of 79 monolingual Spanish-speaking-only obese Latinos (65 female, 14 male) participating in a randomized placebo-controlled trial performed at a Hispanic community mental health center. Participants were categorized as meeting the criteria for BED (n = 40) or obese non-binge-eating controls (n = 39) based on diagnostic and semistructured interviews administered by fully bilingual research clinicians trained specifically for this study.

RESULTS

Analyses revealed that negative attitudes toward obesity did not differ significantly between the BED and non-binge-eating groups nor were they correlated with the intensity of eating disorder psychopathology (eg, levels of weight and shape concerns). Overall, the levels of negative attitudes toward obesity in this Latino/Latina group are similar to those reported previously for samples of English-speaking primarily white obese persons.

DISCUSSION

These findings suggest that it may be obesity per se-rather than eating disorder psychopathology or body image-that heightens vulnerability to negative weight-based attitudes.

Etiology, Treatment and Prevention of Obesity in Childhood and Adolescence: A Decade in Review

Childhood obesity has become an epidemic on a worldwide scale. This article gives an overview of the progress made in childhood and adolescent obesity research in the last decade, with a particular emphasis on the transdisciplinary and complex nature of the problem. The following topics are addressed: 1) current definitions of childhood and adolescent overweight and obesity; 2) demography of childhood and adolescent obesity both in the US and globally; 3) current topics in the physiology of fat and obesity; 4) psychosocial correlates of childhood and adolescent overweight and obesity; 5) the three major obesity-related behaviors, i.e. dietary intake, physical activity and sleep; 6) genes components of childhood and adolescent obesity; 7) environment and childhood and adolescent obesity; and 8) progress in interventions to prevent and treat childhood obesity. The article concludes with recommendations for future research, including the need for large-scale, high dose and long-term interventions that take into account the complex nature of the problem.

Assessing the impact of obesity on labor market outcomes

We study the effect of obesity on employment, using rich data from the British National Child Development Study (NCDS). The results show a significant negative association between obesity and employment even after controlling for a rich set of demographic, socioeconomic, environmental and behavioral variables. In order to account for the endogeneity of obesity, we use and assess instruments introduced by Cawley (2004); the obesity status of biological relatives. Using parental obesity as an instrument, we show that the association between obesity and employment is no longer significant. Similar results are obtained in a model of first differences. We provide a number of different checks on the instruments, by exploiting the richness of the NCDS data. The results show mixed evidence regarding the validity of the instruments.

Attitudes toward obesity in obese persons: a matched comparison of obese women with and without binge eating

No research has compared expressions of weight bias across different subgroups of obese individuals. This study compared attitudes toward and beliefs about obesity in women with and without binge eating disorder (BED) and examined whether these attitudes are related to psychological factors. Fifty obese women with BED were compared with an age- and body mass index (BMI)-matched group of 50 obese women without BED on a battery of established measures of anti-fat attitudes and beliefs about weight controllability and psychological factors (self-esteem, depression, and eating disorder features). The ageand BMI-matched groups did not differ with respect to beliefs about obesity or attitudes toward obese persons, or in self-esteem or depression. Correlational analyses conducted separately within each group revealed that women with BED who reported more favorable attitudes towards obese persons had higher self-esteem and lower levels of depression, whereas there were no significant associations between these variables among women without BED. In addition, weight controllability beliefs and eating disorder features were unrelated to self-esteem and depression in both groups. These findings suggest that stigmatizing attitudes endorsed by obese persons are neither tempered nor worsened by psychological distress or eating pathology. Given that stigmatizing attitudes did not differ between obese women with and without BED, it may be that obesity itself, rather than psychological features or disordered eating, increases vulnerability to negative weight-based attitudes. Potential implications for stigma reduction efforts and clinical practice are discussed.

Body weight and smoking initiation: evidence from Add Health

In volume 23, issue 2 of this journal, Cawley, Markowitz and Tauras used data from the National Longitudinal Survey of Youth 1997 Cohort to estimate the relationship between body weight and smoking initiation. Using maternal obesity status as an instrument, they found strong evidence that overweight females between the ages of 12 and 21 were more likely to initiate smoking. Drawing on data from the National Longitudinal Study of Adolescent Health, we reexamine the relationship between body weight and smoking initiation. Our results are generally consistent with those of Cawley, Markowitz and Tauras.

Implicit Theories of Body Weight: Entity Beliefs Can Weigh You Down

The current research extended the implicit theory approach to a weight management context and merged it with value expectancy theory. Three studies investigated the hypothesis that individuals are especially unlikely to self-regulate effectively after dieting setbacks when they believe body weight to be fixed ( entity theory) rather than malleable ( incremental theory). Study 1 examined avoidant coping after a hypothetical dieting setback. Study 2 examined the implicit theory—avoidant coping relation after naturally occurring challenges to participants’ weight-loss goals. Across both studies, entity theorists, relative to incremental theorists, reported more avoidant coping after setbacks. In Study 2, avoidant coping, in turn, predicted difficulty achieving weight-loss success. Study 3 manipulated implicit theories of weight to test the causal effects of implicit theories on effortful regulation. Entity theorists, relative to incremental theorists, reported less persistence following setbacks. Across the three studies, expectations about the potential for future dieting success mediated the link between implicit theory and self-regulation.

Overweight in children and adolescents associated with TV viewing and parental weight: Project HeartBeat!

BACKGROUND

Parental obesity and TV viewing are risk factors for childhood obesity. This study assessed the association of children's TV viewing and computer use with body mass and examined whether parental weight status modified the association.

METHODS

Cross-sectional associations of parental weight status, hours of TV viewing and computer use, and children's body composition were studied in a subsample of 526 black and nonblack children, aged 8, 11, and 14 years at baseline, enrolled in Project HeartBeat!, a longitudinal study of cardiovascular disease risk factors, 1991-1995. BMI, fat-free mass (FFM), and percent body fat (PBF) were calculated from children's body composition measured at baseline. Children's TV viewing and computer use habits and parental height and weight were self-reported. Multivariate regression analysis was used in assessing inter-relations of parental weight status and child's TV viewing and computer use habits with BMI, FFM, PBF, and risk for overweight status (BMI > or =85th percentile), adjusting for age, gender, race, and Tanner stage.

RESULTS

Children of one or two overweight/obese parents watched an average of 22+/-6 minutes or 30+/-11 minutes more TV per day than children of normal-weight parents, respectively (both p<0.01). In multivariate regression analyses, BMI and PBF increased significantly by 0.42 kg/m(2) and 1.14% (both p<0.001), respectively, for each hour of TV watched among children with overweight parents, but not for those with normal-weight parents (p(interaction)<0.05). Similar results were observed for total screen time.

CONCLUSIONS

These study findings are consistent with a genetic contribution of parental weight; however, overweight/obese parents may also exhibit behavior patterns that negatively influence children's TV viewing and have an impact on child overweight status. The effect of parental BMI on children's BMI may have both a genetic and an environmental linkage.

Intergenerational influences on childhood body mass index: the effect of parental body mass index trajectories

BACKGROUND

Parental obesity in adulthood is a strong determinant of offspring obesity. Whether parental body mass index (BMI; in kg/m2) at earlier life stages is associated with offspring BMI is unknown.

OBJECTIVE

The main objective was to assess whether recent BMI of parents in adulthood and their recent BMI gain are more strongly associated with offspring BMI than are BMI or changes in parental BMI in childhood.

DESIGN

Two generations in the 1958 British birth cohort were studied, including cohort members (parents' generation) with BMI at 7, 11, 16, 23, and 33 y (n = 16,794) and a one-third sample of their offspring selected in 1991 aged 4-18 y (n = 2908). We applied multilevel models to allow for within-family correlations.

RESULTS

Childhood BMI increased on average by 0.25-1.10 between the 2 generations, depending on sex and age group, and overweight/obesity increased from 10% to 16%. Parents' BMI in childhood and adulthood independently influenced offspring BMI, but no significant difference in the strength of influence was observed. For example, adjusted increase in BMI for offspring aged 4-8 y was equivalent to 0.37 and 0.23 for a 1-SD increase in maternal BMI at 7 and 33 y, respectively. Similar patterns were observed for risk of overweight/obesity and for paternal BMI at most ages.

CONCLUSIONS

Excessive BMI gains of parents during childhood and adulthood were associated with a higher BMI and risk of obesity in the offspring. Reductions in the incidence of child obesity in the current population may reduce obesity in future generations.

Motor proficiency relationships among siblings

The purpose of this study was to examine motor proficiency relations of siblings. 23 sibling pairs ages 5 to 13 years were studied. Motor proficiency was assessed by the Bruininks-Oseretsky Test of Motor Proficiency-Short Form of 14 items, adjusting for Body Mass Index percentile, age, and sex. The association among siblings' overall motor proficiency was not statistically significant. When each of the 14 items in the test was examined separately, significant associations were found. Items positively associated among siblings included walking on a balance beam, tapping feet and making circles, and sorting shape cards. Copying a picture of overlapping pencils and making dots in circles were inversely related. The results indicate that siblings may share certain motor-skill components of balance, bilateral coordination, and upper limb speed or dexterity, but do not necessarily have the same global motor competence. Additional research is needed to explain relations in motor skills among siblings.

Tooth loss and obesity in a defined Swedish population

Aims: To explore the association between tooth loss and obesity in an adult Swedish population, and to investigate the influence of socioeconomy, life-style, and co-morbidity. Methods: A cross-sectional population health survey conducted in 2001—2005 in 2816 randomly selected Swedish men and women (age: 30—74 years; participation rate 76%). Main measures were; tooth loss: < 20 remaining teeth (self-reported), general obesity: BMI≥30 kg m-2, abdominal obesity: waist circumference >88 in women and >102 cm in men. Adjustments were made for socioeconomy, life-style, and co-morbidity. Results: 420 individuals (21.2%) had < 20 remaining teeth: 30—59 years 6.0%, 60—74 years 53.5%. Mean BMI was similar in men and women (26.9 kg m-2), however, both general and abdominal obesity was still more frequent among women (both p < 0.001). There was a significant interaction between age and tooth loss in the association with both general (p = 0.004) and abdominal obesity (p < 0.011) in men. In participants below 60 years of age, the association between tooth loss and general obesity (OR 2.17 [95% CI 1.51 — 3.12]) and abdominal obesity (2.23 [1.58 — 3.15]), respectively, was statistically significant independent of age and gender, and remained so also when accounting for differences in socioeconomy, life-style, and co-morbidity. There was no similar association in those 60 years or older. The findings in men and women were robust and concordant. Conclusions: Common mechanisms for oral health and obesity should be explored more also including longitudinal designs. The findings are important for targeting comprehensive interventions against obesity and tooth loss, especially among younger adults.

Are employers discriminating with respect to weight? European Evidence using Quantile Regression

The aim of this research is to investigate the relationship between obesity and wages, using data for nine countries from the European Community Household Panel (ECHP) over the period 1998-2001. We improve upon the existing literature by adopting a Quantile Regression approach to characterize the heterogenous impact of obesity at different points of the wage distribution. Our results show that (i) the evidence obtained from mean regression and pooled analysis hides a significant amount of heterogeneity as the relationship between obesity and wages differs across countries and wages quantiles and (ii) cultural, environmental or institutional settings do not seem to be able to explain differences among countries, leaving room for a pure discriminatory effect hypothesis.

Genetic influences on the difference in variability of height, weight and body mass index between Caucasian and East Asian adolescent twins

OBJECTIVE

Twin studies are useful for investigating the causes of trait variation between as well as within a population. The goals of the present study were two-fold: First, we aimed to compare the total phenotypic, genetic and environmental variances of height, weight and BMI between Caucasians and East Asians using twins. Secondly, we intended to estimate the extent to which genetic and environmental factors contribute to differences in variability of height, weight and BMI between Caucasians and East Asians.

DESIGN

Height and weight data from 3735 Caucasian and 1584 East Asian twin pairs (age: 13-15 years) from Australia, China, Finland, Japan, the Netherlands, South Korea, Taiwan and the United States were used for analyses. Maximum likelihood twin correlations and variance components model-fitting analyses were conducted to fulfill the goals of the present study.

RESULTS

The absolute genetic variances for height, weight and BMI were consistently greater in Caucasians than in East Asians with corresponding differences in total variances for all three body measures. In all 80 to 100% of the differences in total variances of height, weight and BMI between the two population groups were associated with genetic differences.

CONCLUSION

Height, weight and BMI were more variable in Caucasian than in East Asian adolescents. Genetic variances for these three body measures were also larger in Caucasians than in East Asians. Variance components model-fitting analyses indicated that genetic factors contributed to the difference in variability of height, weight and BMI between the two population groups. Association studies for these body measures should take account of our findings of differences in genetic variances between the two population groups.

Physique Correlates with Reproductive Success in an Archival Sample of Delinquent Youth

This study examines predictions from evolutionary psychology about relationships between physique and reproductive success using longitudinal data on 200 delinquent youth from Sheldon's (1949) somatotype research. Number of children (offspring count) in 1979 was used as the measure of reproductive success. Nonparametric bootstrap correlations and confidence intervals were calculated between offspring count and 11 measures of physique (endomorphy, mesomorphy, ectomorphy, andromorphy, gynomorphy, primary structural integration, secondary structural integration, general strength, hand strength, height, and weight). There were noteworthy correlations with mesomorphy, andromorphy, gynomorphy, primary structural integration, secondary structural integration, general strength, and hand strength, all in the directions predicted by evolutionary psychology. While no prediction was made for endomorphy, ectomorphy, or weight; height was expected to be correlated with offspring count, but this study did not find support for this relationship.

Childhood obesity: genetic and environmental overlap with normal-range BMI

OBJECTIVE

To understand the overlap between the etiology of obesity and normal variation in BMI in children.

METHODS AND PROCEDURES

Height and weight data were available from a large UK representative sample of twins: 2,342 same-sex pairs at 7 years and 3,526 same-sex pairs at 10 years. The twin method and model-fitting techniques were used to estimate genetic and environmental contributions to BMI. DeFries-Fulker (DF) extremes analysis was used to investigate genetic and environmental influences on the mean difference between obese and normal-weight children. Obesity was classified using the International Obesity Task Force (IOTF) criteria.

RESULTS

At both ages, BMI and obesity were highly heritable (0.60-0.74) and only modestly influenced by shared environmental factors (0.12-0.22). Extremes analyses indicated that genetic and environmental influences on obesity are quantitatively and qualitatively similar to those operating across the range of BMI.

DISCUSSION

Obesity is the extreme of the same genetic and environmental factors responsible for variation throughout the distribution of BMI. This finding implies that genes that influence obesity will also be associated with BMI in the normal range, and similar environmental influences will affect BMI in the clinical and normal range. Knowing that obesity is influenced by the same genetic and environmental factors that affect weight at all levels has implications for investigating the mechanisms for weight gain and developing interventions for weight control.

Evidence for a strong genetic influence on childhood adiposity despite the force of the obesogenic environment

BACKGROUND

Body mass index (BMI) has been shown to be highly heritable, but most studies were carried out in cohorts born before the onset of the "obesity epidemic."

OBJECTIVE

We aimed to quantify genetic and environmental influences on BMI and central adiposity in children growing up during a time of dramatic rises in pediatric obesity.

DESIGN

We carried out twin analyses of BMI and waist circumference (WC) in a UK sample of 5092 twin pairs aged 8-11 y. Quantitative genetic model-fitting was used for the univariate analyses, and bivariate quantitative genetic model-fitting was used for the analysis of covariance between BMI and WC.

RESULTS

Quantitative genetic model-fitting confirmed substantial heritability for BMI and WC (77% for both). Bivariate genetic analyses showed that, although the genetic influence on WC was largely common to BMI (60%), there was also a significant independent genetic effect (40%). For both BMI and WC, there was a very modest shared-environment effect, and the remaining environmental variance was unshared.

CONCLUSIONS

Genetic influences on BMI and abdominal adiposity are high in children born since the onset of the pediatric obesity epidemic. Most of the genetic effect on abdominal adiposity is common to BMI, but 40% is attributable to independent genetic influences. Environmental effects are small and are divided approximately equally between shared and non-shared effects. Targeting the family may be vital for obesity prevention in the earliest years, but longer-term weight control will require a combination of individual engagement and society-wide efforts to modify the environment, especially for children at high genetic risk.