An actor-based model of social network influence on adolescent body size, screen time, and playing sports

Recent studies suggest that obesity may be "contagious" between individuals in social networks. Social contagion (influence), however, may not be identifiable using traditional statistical approaches because they cannot distinguish contagion from homophily (the propensity for individuals to select friends who are similar to themselves) or from shared environmental influences. In this paper, we apply the stochastic actor-based model (SABM) framework developed by Snijders and colleagues to data on adolescent body mass index (BMI), screen time, and playing active sports. Our primary hypothesis was that social influences on adolescent body size and related behaviors are independent of friend selection. Employing the SABM, we simultaneously modeled network dynamics (friendship selection based on homophily and structural characteristics of the network) and social influence. We focused on the 2 largest schools in the National Longitudinal Study of Adolescent Health (Add Health) and held the school environment constant by examining the 2 school networks separately (N?=?624 and 1151). Results show support in both schools for homophily on BMI, but also for social influence on BMI. There was no evidence of homophily on screen time in either school, while only one of the schools showed homophily on playing active sports. There was, however, evidence of social influence on screen time in one of the schools, and playing active sports in both schools. These results suggest that both homophily and social influence are important in understanding patterns of adolescent obesity. Intervention efforts should take into consideration peers' influence on one another, rather than treating "high risk" adolescents in isolation.     

Weight gain in adolescents and their peers

Despite the urgent public health implications, relatively little is yet known about the effect of peers on adolescent weight gain. We describe trends and features of adolescent BMI in a nationally representative dataset and document correlations in weight gain among peers. We find strong correlations between own body mass index (BMI) and peers’ BMI's. Though the correlations are especially strong in the upper ends of the BMI distribution, the relationship is smooth and holds over almost the entire range of adolescent BMI. Furthermore, the results are robust to the inclusion of school fixed effects and basic controls for other confounding factors such as race, sex, and age. Some recent research in this area considers whether or not adolescent weight gain is caused by peers. We discuss the econometric issues in plausibly estimating such effects while accounting for growth spurts and difficulties in defining adolescent obesity. While our work identifies correlations between adolescent BMI and peers’ BMI, it is not intended to and cannot fully address the existence of endogenous peer effects.     

School level contextual factors are associated with the weight status of adolescent males and females

Objective: To determine whether school context influences the BMI of adolescent males and females. Methods and Procedures: Our sample was 17,007 adolescents (aged 12–19) from the National Longitudinal Study of Adolescent Health (Add Health). We used gender‐stratified multilevel modeling to examine the contribution of schools to the overall variance in adolescent BMIs, calculated from self‐reported weight and height. We then examined the associations of individual attributes with BMI after controlling for the average BMI of the school and the association of two school‐level variables with BMI. Results: Participants attended schools that were segregated by race/ethnicity and socioeconomic status (SES). In females, when controlling only for individual‐level attributes, individual household income was inversely associated (β = ?0.043, P = 0.01) while Hispanic (β = 0.89, P < 0.001) and black (β = 1.61, P < 0.001) race/ethnicity were positively associated with BMI. In males, Hispanic (β = 0.67, P < 0.001) race/ethnicity was positively associated with BMI; there was no difference in the BMIs of blacks compared with whites (β = 0.24, P = 0.085). After controlling for the school racial/ethnic makeup and the school level median household income, the relationship between individual race/ethnicity and BMI was attenuated in both male and female adolescents. Higher school level median household income was associated with lower individual BMIs in adolescent girls (γ = ?0.37, P < 0.001) and boys (γ = ?0.29, P < 0.001) suggesting a contextual effect of the school. Discussion: Male and female adolescents attending schools with higher median household incomes have on average lower BMIs. Resources available to or cultural norms within schools may constitute critical mechanisms through which schools impact the BMI of their students.     

Blood Pressure in Adolescence and Early Adulthood Related to Obesity and Birth Size

Objective: Obesity is an established risk factor for higher systolic (SBP) and diastolic (DBP) blood pressure in adolescence and early adulthood, but birth size may also have a role. We analyzed the effects of adolescent and adult obesity and birth size on BP in the young adult. Research Methods and Procedures: In a prospective longitudinal study, anthropometric measurements were obtained at birth on 67 boys and 67 girls bom in Boston. Their body mass indices (BMI) and BP were recorded 17 years and 30 years later. Results: For women, adolescent and early adult obesity appeared to be the stronger determinants of higher BP, although smaller head and chest circumferences at birth may also be related. We found some evidence of birth (ponderal index [PI] and head circumference) anthropometric influences on age 17 BP levels in boys. By age 30, body mass variables were the dominant predictors of male BP levels. Female BMI at age 17 was positively correlated with birth adiposity (PI), but BMI at 30 was related only to age 17 BMI. Similarly, male BMI at 17 years was higher for those who weighed more at birth, but BMI at 30 years was again related only to age 17 BMI. Discussion: We conclude that adult weight and weight gain are the major determinants of adult BP.     

Parenting Characteristics in the Home Environment and Adolescent Overweight: A Latent Class Analysis

Parenting style and parental support and modeling of physical activity and healthy dietary intake have been linked to youth weight status, although findings have been inconsistent across studies. Furthermore, little is known about how these factors co‐occur, and the influence of the coexistence of these factors on adolescents' weight. This article examines the relationship between the co‐occurrence of various parenting characteristics and adolescents' weight status. Data are from Project EAT (eating among teens), a population‐based study of 4,746 diverse adolescents. Theoretical and latent class groupings of parenting styles and parenting practices were created. Regression analyses examined the relationship between the created variables and adolescents' BMI. Having an authoritarian mother was associated with higher BMI in sons. The co‐occurrence of an authoritarian mother and neglectful father was associated with higher BMI for sons. Daughters' whose fathers did not model or encourage healthy behaviors reported higher BMIs. The co‐occurrence of neither parent modeling healthy behaviors was associated with higher BMIs for sons, and incongruent parental modeling and encouraging of healthy behaviors was associated with higher BMIs in daughters. Although, further research into the complex dynamics of the home environment is needed, findings indicate that authoritarian parenting style is associated with higher adolescent weight status and incongruent parenting styles and practices between mothers and fathers are associated with higher adolescent weight status.     

The Relationship Between Weight and Psychological Functioning Among Adolescent Girls

This study investigated whether Body Mass Index (BMI) was associated with various aspects of psychological functioning in a sample of largely Caucasian adolescent girls. Three hundred sixty-five adolescent girls ranging from ages 14 through 19 were assessed for general psychological functioning utilizing the Symptom Checklist-90-Revised (SCL-90-R), and functioning specific to eating, shape and weight utilizing the Eating Disorders Inventory (EDI). Excess weight was associated with higher scores on the Bulimia, Body Dissatisfaction and Drive for Thinness subscales of the EDI. Excess weight was not, however, associated with general psychopathology or any of the subscales of the SCL-90-R. The results suggest that excess weight may carry risk for pathology specifically related to eating, shape and weight in adolescent girls, but not for general forms of psychopathology.     

Exploring the factors contributing to sibling correlations in BMI: a study using the Panel Study of Income Dynamics

Understanding the mechanisms contributing to correlated BMI outcomes in a social network such as siblings will help policy makers reduce the burden of disease associated with obesity. There are two potential mechanisms explaining correlated BMI outcomes in a biologically related social network: (i) time constant factors such as genetic heritability and habits formed during childhood and (ii) factors that change over time some of which are dependent on the frequency of interactions between the social network, for example, social norms shaped by the social network's shifting attitudes towards weight and behaviors related to weight, or environmental factors like opportunities for exercise. This study aims to distinguish between time constant factors from factors that are likely to change over time to gain a better understanding of the mechanisms explaining the correlation in sibling BMI. We exploit data from the Panel Study of Income Dynamics (PSID) over 1999-2007 estimating the correlation in BMI for adult siblings who currently live in separate households but grew-up in the same household and adolescent siblings currently living in the same household to isolate the influence of factors that change over time. The findings indicate that time constant factors explain some of the overall correlation in sibling BMI for both cohorts of siblings. Factors that change over time only significantly impact on the overall correlation in BMI for adolescent siblings suggesting if there is a social network influence on correlations in BMI this is facilitated by sharing the same household.     

Predicting treatment initiation in a family-based adolescent overweight and obesity intervention

Little is known about factors associated with treatment initiation in overweight and obese adolescents. This study investigated parent-reported adolescent demographic, adolescent health, and parent motivation factors associated with initiation of a family-based adolescent overweight and obesity intervention. A telephone survey was completed by 349 parents calling to register their interest in participating in a cognitive behavioral lifestyle intervention for adolescent overweight and obesity. A total of 172 families (49.3%) returned their consent form to initiate treatment. A binomial logistic regression, with predictors entered in three blocks: (i) adolescent demographic (adolescent age, gender, adolescent BMI-for-age z-score, parent BMI); (ii) adolescent health (perceived adolescent physical and mental health, presence of an adolescent physical health problem or mental health problem, medication intake); and (iii) parent motivation (perceived adolescent weight category, concern about adolescent weight, importance of adolescent weight, confidence in adolescent capacity to change weight, priority of adolescent weight loss, discrepancy between adolescent current and ideal weight, previous weight loss attempts), was significant (χ2 (16) = 35.19, P = 0.004) accounting for 12.4-16.5% (95% confidence interval) of treatment initiation variance. Parent-reported adolescent physical health problem, parent perception of adolescent weight category, parent priority of adolescent weight loss, and parent perception of discrepancy between adolescent current and ideal weight were significant in the model. These findings indicate that data collected at intake are associated with treatment initiation and highlight the role of assessing and enhancing treatment motivation from initial contact.     

Is DL-Fenfluramine a Potentially Helpful Drug Therapy in Overweight Adolescent Subjects?

We have studied the therapeutic effects of two different doses (30 mg and 60 mg, twice daily) of DL-fen-fluramine (DL-F) in, respectively, prepuberal (11–13 years old) and adolescent subjects (14–17 years old). Sixty-eight obese subjects were recruited for this study (22 boys, 36 girls, aged 10–17 years old) with body mass index ranging from 24.5 to 44.0 kg/m², absolute weight ranging from 37.0 to 119.5 kg and % over IBW ranging from 122% to 260%. Results were compared to a placebo treated group of obese adolescent patients (n=17), 6 boys and 11 girls, aged 10–17 years old, BMI ranging from 26–44 kg/m², absolute weight 53.1 to 96.5 kg, and with 129% to 253% over IBW. In the DL-F-treated subjects most patients (n=41) had a continuous weight loss during 12 months but 27 individuals were unable to lose any additional weight after the initial 6 months of the trial. Taken together 65% of all patients lost weight during DL-F treatment (12 months) whereas only 17.4% of the placebo group lost a significant (>10% BMI) amount of excess weight. Also the placebo group had a higher withdrawal rate (57%) as compared with the DL-F-treated group (24%). There was a significant (p<0.05) decrease of the mean & SD of the BMI (at 6 and 12 months of therapy). No significant change of the BMI was observed for control group. Minor adverse side effects consisted of a brief period of drowsiness and dry mouth. Our findings indicated that the continuous administration of DL-Fenfluramine might help obese adolescent subjects adhere to a diet and to maintain the weight loss achieved without major or harmful adverse effects .     

Body mass index and depressive symptoms: instrumental‐variables regression with genetic risk score

The causal role of obesity in the development of depression remains uncertain. We applied instrumental‐variables regression (Mendelian randomization) to examine the association of adolescent and adult body mass index (BMI) with adult depressive symptoms. Participants were from the Young Finns prospective cohort study (n = 1731 persons, 2844 person‐observations), with repeated measurements of BMI and depressive symptoms (modified Beck's Depression Inventory). Genetic risk score of 31 single nucleotide polymorphisms previously identified as robust genetic markers of body weight was used as a proxy for variation in BMI. In standard linear regression analysis, higher adult depressive symptoms were predicted by higher adolescent BMI (B = 0.33, CI = 0.06–0.60, P = 0.017) and adult BMI (B = 0.47, CI = 0.32–0.63, P < 0.001). These associations were replicated in instrumental‐variables analysis with genetic risk score as instrument (B = 1.96, CI = 0.03–3.90, P = 0.047 for adolescent BMI; B = 1.08, CI = 0.11–2.04, P = 0.030 for adult BMI). The association for adolescent BMI was significantly stronger in the instrumented analysis compared to standard regression (P = 0.04). These findings provide additional evidence to support a causal role for high BMI in increasing symptoms of depression. However, the present analysis also demonstrates potential limitations of applying Mendelian randomization when using complex phenotypes.     

Body mass index gain, fast food, and physical activity: effects of shared environments over time

Objective : The magnitude of environmental vs. genetic effects on BMI, diet, and physical activity (PA) is widely debated. We followed a sibling cohort (where individuals shared households in childhood and adolescence) to young adulthood (when some continued sharing households and others lived apart) to examine the role of discordant environments in adult twins’ divergent trends in BMI and health behaviors and to quantify the variation in BMI and behavior among all siblings that is attributable to environmental and additive genetic effects. Research Methods and Procedures : In the National Longitudinal Study of Adolescent Health, siblings sharing households for ≥10 years as adolescents (mean age = 16.5 ± 1.7 years; N = 5524) were followed into adulthood (mean = 22.4 ± 1.8 years; N = 4368), self‐reporting PA, sedentary behavior, and dietary characteristics. Adult BMI and adolescent z scores were derived from measured height and weight. Results : Compared with those living together, twins living apart exhibited greater discordance in change in BMI, PA, and fast food intake from adolescence to adulthood. Adolescent household environments accounted for 8% to 10% of variation in adolescent fast food intake and sedentary behaviors and 50% of variation in adolescent overweight. Adolescent household effects on PA were substantially greater in young adulthood (accounting for 50% of variation) vs. adolescence. Young adult fast food intake was significantly affected by young adult household environment, accounting for 12% of variation. Discussion : These findings highlight important environmental influences on BMI, PA, and fast food intake during the transition to adulthood. Household and physical environments play an important role in establishing long‐term behavior patterns.     

Change in BMI Accurately Predicted by Social Exposure to Acquaintances

Research has mostly focused on obesity and not on processes of BMI change more generally, although these may be key factors that lead to obesity. Studies have suggested that obesity is affected by social ties. However these studies used survey based data collection techniques that may be biased toward select only close friends and relatives. In this study, mobile phone sensing techniques were used to routinely capture social interaction data in an undergraduate dorm. By automating the capture of social interaction data, the limitations of self-reported social exposure data are avoided. This study attempts to understand and develop a model that best describes the change in BMI using social interaction data.We evaluated a cohort of 42 college students in a co-located university dorm, automatically captured via mobile phones and survey based health-related information. We determined the most predictive variables for change in BMI using the least absolute shrinkage and selection operator (LASSO) method. The selected variables, with gender, healthy diet category, and ability to manage stress, were used to build multiple linear regression models that estimate the effect of exposure and individual factors on change in BMI. We identified the best model using Akaike Information Criterion (AIC) and R².This study found a model that explains 68% (p<0.0001) of the variation in change in BMI. The model combined social interaction data, especially from acquaintances, and personal health-related information to explain change in BMI.This is the first study taking into account both interactions with different levels of social interaction and personal health-related information. Social interactions with acquaintances accounted for more than half the variation in change in BMI. This suggests the importance of not only individual health information but also the significance of social interactions with people we are exposed to, even people we may not consider as close friends.     

Observable Weight Distributions and Children's Individual Weight Assessment

Social networks theory suggests obesity is “contagious” within peer groups in that known friends highly influence weight. On the other hand, an alternative model suggests that observable weight distributions affect perception of one's own obesity level. We examine whether the BMI levels of the most obese classmates in the individual student's grade by gender is positively associated with “under‐assessment” of obesity and overweight (i.e., independently measured obesity or overweight, but subjective self‐assessment of normal weight). The data are the 2004–2005 School Physical Activity and Nutrition III (SPAN), a stratified, multistage probability sample of 4th, 8th, and 11th grade public school children in Texas. We used logistic regression to test whether the gender‐specific 85th percentile BMI level within the individual student's grade at their school is positively associated with “under‐assessment” of obesity and overweight. The results show that students are much more likely to under‐assess their own weight if the gender‐specific 85th percentile BMI level is higher in their grade at their school. These data suggest that observable weight distributions play a key role in the obesity epidemic.     

Predictors of attrition and weight loss in an adolescent weight control program

Objective: To evaluate demographic and psychosocial predictors of attrition and weight loss in a behaviorally based adolescent weight control trial. Methods and Procedures: Adolescents (N = 76) aged 13–16 years and 20–80% overweight (M = 60.56%, s.d. = 15.17%) received standard group‐based behavioral treatment as part of a randomized trial comparing different activity interventions for overweight adolescents. Anthropometric and psychosocial measures were obtained at baseline and after the 16‐week intervention. Results: Higher parent (P < 0.01) and adolescent BMI (P < 0.05) at baseline, as well as ethnic minority status (P < 0.05) were significantly associated with attrition in univariate analyses. Parent BMI remained the only significant predictor of attrition in multivariate analyses. BMI change for completers (N = 62) was highly variable, ranging from ?6.09 to +1.62 BMI units. Male gender (P < 0.01) was a significant predictor of reduction in BMI, whereas not being from an ethnic minority group (P < 0.05) and attendance at group sessions (P = 0.05) were associated with ≥5% absolute weight loss in multivariate analyses. Absolute weight loss during the first 4 weeks of the program was strongly associated with weight loss (pr = 0.44, P < 0.001) during the remainder of the intervention. Psychosocial variables were unrelated to attrition or treatment outcome. Discussion: These findings highlight the potential importance of attending to parental BMI in efforts to retain adolescent participants in treatment, as well as the need to develop weight control interventions that are more effective for ethnic minority youth.     

The Changing Body Mass–Mortality Association in the United States: Evidence of Sex-Specific Cohort Trends from Three National Health and Nutrition Examination Surveys

The association between body mass index (BMI) categories and mortality remains uncertain. Using three National Health and Nutrition Examination Surveys covering the 1971–2006 period for cohorts born between 1896 and 1968, this study estimates separately for men and women models for year-of-birth (cohort) and year-of-observation (period) trends in how age-specific mortality rates differ across BMI categories. Among women, relative to the normal weight (BMI 18.5–24.9 kg/m²), there are increasing trends in mortality rates for the overweight (BMI 25–29.9) or obese (BMI ≥ 30). Among men, mortality rates relative to the normal weight decrease for the overweight, do not change for the moderately obese (BMI 30–34.9), and increase for the severely obese (BMI ≥ 35). Period and cohort trends are similar, but the cohort trends are more consistent. In the latest cohorts, compared with the normal weight, mortality rates are 50 percent lower for overweight men, not different for moderately obese men, and 100–200 percent higher for severely obese men and for overweight or obese women. For U.S. cohorts born after the 1920s, a lower overweight than normal weight mortality is confined to men. I speculate on possible reasons why the mortality association with overweight and obesity varies by sex and cohort.     

Association Between Prolactinoma and Body Mass Index

ObjectiveObesity is increasing worldwide, and certain endocrine disorders may contribute to weight gain. While several studies have examined the association between weight gain and prolactinomas, the results are conflicting. Therefore, this study aimed to determine if body mass index (BMI) is higher among those with prolactinomas than those without.MethodsWe identified patients ≥18 years of age referred to an endocrine clinic between 2008 and 2018 with newly diagnosed prolactinomas. We extracted the relevant information, and comparative data was obtained from the 2015-2016 National Health and Nutrition Examination Survey.ResultsIn total, 34 cases met the inclusion criteria. One third of the patients described weight gain at presentation. Those with prolactinomas had a significantly higher BMI than the National Health and Nutrition Examination Survey population (median BMI, 29.8 kg/m² vs 28.3 kg/m², P = .0048). When stratified by sex, only men with prolactinomas had an increased BMI compared with the controls. Moreover, those with prolactinomas had a higher prevalence of class II obesity (BMI ≥ 35 kg/m²) than the survey population (35% vs 18%, P = .01). Among the prolactinoma patients, a correlation was observed between BMI and log-transformed prolactin levels (R² = 0.4, P = .0002).ConclusionWeight gain can be a presenting symptom for patients with newly diagnosed prolactinomas. Those with prolactinomas have a higher BMI and an increased prevalence of class II obesity. These findings suggest that patients should be counseled regarding weight issues related to prolactinomas at presentation and should be a consideration in the investigative and treatment algorithm of prolactinomas.     

Effects of serum irisin,neuregulin 4, and weight management on obese adolescent girls with polycystic ovary syndrome

The study is aimed at investigating the association of serum irisin, neuregulin 4 (NRG4), and anti-müllerian hormone (AMH) with adolescent obesity with polycystic ovary syndrome (PCOS) and the efficacy of weight management interventions. Serum levels of irisin, NRG4, AMH, sex steroid hormone, body mass index (BMI), serum insulin, and C-peptide were measured in 52 obese adolescent girls with PCOS (PCOS group) and 43 obese adolescent girls without PCOS (non-PCOS group). The levels of AMH, NRG4, serum irisin, sex steroid hormones, BMI, serum insulin, and C-peptide were evaluated in obese PCOS girls before and after one year weight management. The levels of AMH, serum insulin, NRG4, and total testosterone of PCOS group were significantly higher than those of non-PCOS group. On the contrary, serum irisin and serum C-peptide in PCOS group were significantly lower than that in non-PCOS group. The levels of fat mass, percent body fat, total testosterone, AMH, NRG4, and serum insulin in the obese girls with PCOS showed significant decreases compared with before weight management intervention. On the contrary, after one year of body weight management intervention, serum irisin and serum C-peptide was significantly increased. Adolescent obesity complicated with PCOS is significantly associated with glucose and lipid metabolism and sex steroid hormone disorders, but the exact pathophysiological and clinical features are highly variable. Weight management intervention can significantly improve the clinical symptoms and hematological indicators, serum irisin and NRG4 can be used as two essential biomarkers for evaluating weight management.     

BMI in Japanese children since 1948: no evidence of a major rise in the prevalence of obesity in Japan

The dramatic world-wide trend towards increasing body weight seems to be less obvious in the Japanese population. The aim of this study is to extract potentially useful information regarding childhood and adolescence obesity in Japan from series of mean height and mean body mass index between 1948 and 2003. Mean values for height and weight of Japanese boys and girls aged 5+ to 17+ years were obtained from the "Reports on School Health Survey", Ministry of Education, Culture, Sports, Science and Technology, comprising approximately 4.5% of all children and adolescents in Japan between 1948 and 2003. The data were fitted by the Preece and Baines model (Preece & Baines 1978) in order to obtain estimates of the age of peak height velocity (APHV) and final height. Isochrones for height and BMI were calculated based upon measurements that were obtained at the same chronological ages at different historic epochs. The APHV as estimated by Preece & Baines (1978) has decreased from 14.07 to 12.03 years in Japanese boys, and from 11.80 to 9.92 years in Japanese girls, indicating that the tempo of child and adolescent maturation (maturational tempo) has accelerated. Body height increased by 10.1 cm in near adult 17+ year old Japanese males and by 5.7 cm in 17+ year old Japanese females since 1948. Due to the acceleration and the earlier attainment of adult stature, isochrones for height tend to diverge for prepubertal ages and to converge for postpubertal ages. The same is true for weight. Body weight has increased by 11.8 kg in near adult males, and by 4.4 kg in near adult females. Also BMI has increased since 1948. But in contrast to height and weight, the rise in BMI only reflects the acceleration of the maturational tempo. Tempo-conditioned isochrones for BMI are almost horizontal, and even tended to temporarily decrease during the 60ies and the 70's. The BMI of Japanese children and adolescents dramatically contrasts the recent and historic BMI changes in the Western populations. The present study provides no evidence of any major rise in the prevalence of obesity in Japan as expressed by mean BMI for age and time of birth, and suggests that Japanese children and adolescents may be more resistant against those environmental factors that have caused obesity in the affluent Western societies.     

Correlations with Self-Reported Weight Loss in Overweight U.S. Adults

The authors investigated two issues among overweight men and women in the U.S.: 1) what is the influence of the self-expressed intention to lose weight in the presence of other potential predictors of loss and 2) what are easily identifiable predictors of intentional weight loss during a 1-year recall period. The sample consisted of 1996 overweight men (body mass index (BMI ≥ 27.8 kg/m²) and 2586 overweight women (BMI ≥ 27.3 kg/m²) who answered questions regarding 1-year weight change in a Current Health Topic supplement of the population-based 1989 National Health Interview Survey. Of these overweight persons, 56.8% of men and 72.1% of women attempted to lose weight during the previous year. The most important characteristic associated with weight loss was the expressed intention itself. For any weight loss, the odds ratios (95% confidence intervals) for intention were 4.6 (3.6?5.9) for men and 3.8 (2.8?5.0) for women. Controlling for other factors reduced the odds only slightly, to 4.3 for men and 3.5 for women. Among women, older age, having a greater frequency of blood pressure checks, and being in poorer health reduced the influence of intent as a predictor of loss. To address the second objective, the identification of predictors of intentional 1-year weight loss, analysis was restricted to overweight persons who attempted to lose weight. For both sexes, statistically significant predictors (p<0.05) included never being married, smoking, higher BMI, being diabetic, and having a higher number of blood pressure checks. Being divorced or separated was predictive of weight loss in men only. Also, men were more likely to achieve weight loss than women. In conclusion, 1-year weight loss among the overweight was primarily a function of the intention to lose weight, although other factors contributed to determine whether weight loss was achieved.     

The income body weight gradients in the developing economy of China

Existing theories predict the income gradient of individual body weight to change sign from positive to negative in process of economic development. However, there are only few empirical studies which test this hypothesis. This paper adds to the literature on that topic by investigating the case of China. Using individual and community data from 1991 to 2009 waves of the China Health and Nutrition Survey regression analyses suggest that after controlling for important confounding factors (1) higher income is positively related to future growth of individuals’ BMI in less developed areas (i.e. BMI growth is 0.7–1.5 percentage points higher when comparing the richest with the poorest individuals), but negatively related to BMI growth in more developed areas (i.e. BMI growth is 0.8–1.6 percentage points lower for the richest individuals), and (2) that concentrations of overweight are “trickling down” to lower income ranks as regions become more developed. Moreover, the reversal of the income gradient appears to happen at earlier stages of development for females.