Peer effects in adolescent BMI: evidence from Spain

Income, aging, and the gendered patterns of wellness: Physical health and subjective well-being in China

This article investigates the impact of demographic and socioeconomic inequalities on wellness, composed of both physical health and subjective well-being. We examine how gender inequality moderates the joint effects of aging and income on wellness in China. Utilizing generalized linear mixed model (GLMM), we analyze data from the Chinese General Social Survey (CGSS) spanning from 2003 to 2021. Our results reveal that income inequality disproportionately affects physical health among older, underweight, lower-class females; males are more susceptible to negative impacts on subjective well-being, particularly among lower-class, middle-aged males. These gendered patterns are situated in the contemporary Chinese society and are explained in relation to intra-household distributional inequality and the gender role expectations in the Confucian culture. We also discussed the policy implications of how to reduce the gaps in wellness across social classes, age cohorts, and genders.

Peer effects in weight-related behaviours of young people: A systematic literature review

Individual preferences and beliefs are perpetually shaped by environmental influences, with peers playing a key role in this dynamic process. Compelling evidence from qualitative and quantitative studies has highlighted the significant impact of peer influence on health-related decisions. This systematic literature review critically synthesises findings from 45 studies published between 2011 and 2022, providing a comprehensive understanding of the nature of peer effects on dietary, physical activity and sleep behaviours during youth. The majority of studies indicated that social norms drive directional changes in eating and physical activity. Yet, our analysis revealed a notable gap in exploring alternative mechanisms, including social comparison and social identity, despite their potential relevance. Studies, generally classified as moderate to high quality, predominantly relied on self-reported data, potentially affecting the validity and reliability of measures. Meta-regression analyses suggest a small, but significant association of sample size with the magnitude, sign and significance of the reported peer effects. Moreover, studies focusing on physical activity are more likely to report significant outcomes, whereas findings on peer influence on sleep-related studies tend to reveal less pronounced effects, compared to studies on dietary behaviours. Experimental designs do not appear to increase the likelihood of finding significant effects when compared to other study designs. In conclusion, this synthesis emphasises the need for further research into the underlying mechanisms on peer effects to better inform policy-makers in designing effective policies for improving weight-related behaviours in young people.

A meta-analysis of the relationship between social support and physical activity in adolescents: the mediating role of self-efficacy

Introduction

Social support influences physical activity (PA) in adolescents. However, whether mediating and moderating effects impact the relationship between them or the underlying mechanism remains unclear. This study aimed to investigate the mediating effects of self-efficacy as well as a series of moderating influences using a meta-analytic approach.

Methods

A total of 56 studies published between January 2001 and May 2023 were obtained from the Web of Science, EBSCO, Taylor and Francis, Scopus, Wiley, ProQuest, and CNKI (core) databases, comprising 65 independent samples (total sample size = 47,196).

Results and discussion

The mean weighted correlation coefficients between social, family, peer, and school support and adolescent PA were 0.298, 0.226, 0.256, and 0.142, respectively, which were significant, except for school support. Family support and teenage PA were related, although the connection was moderated by gender and socioeconomic characteristics. While social, family, and peer support had a direct influence on adolescent PA, school support did not. Self-efficacy mediated the relationship between social support and its subtypes and adolescent PA.

Preventing tobacco use from the start: Short- and medium-term impacts on the youth

Adolescent substance use is a persistent global problem and a challenge for society and the public health authorities. In this paper we investigate the impact of a prevention-oriented policy implemented in Icelandic secondary schools from 1997 to 2002 (the "Drug-free Iceland" programme) on country-level smoking rates on the youth. Using a panel data source spanning from 1985 to 2010 and composed both by Iceland and a set of countries where such a type of policy was absent, we apply the Synthetic Control Method to construct the counterfactual of Iceland. Comparing Iceland with this counterfactual, we estimate the effect of the intervention on those aged 15 to 19 -who were the main target of the policy-, during the years of implementation of the programme, and follow their smoking prevalence rates overtime until 2010, when they became adults (25 to 29-years old). Our results show that the intervention reduced youth smoking prevalence on the targeted groups that lasted at least until they became adults. We also find evidence of externalities in the age groups adjacent to those directly targeted by the policy. The results differ by gender, with the impact on females being more marked.

Weight Status and BMI-Related Traits in Adolescent Friendship Groups and Role of Sociodemographic Factors: The European IDEFICS/I.Family Cohort

BACKGROUND

During adolescence, health behaviors and weight status are increasingly influenced by friendship and peer networks. This paper examines resemblances in weight-related characteristics and how they differ by sociodemographic factors.

METHODS

Over 3,000 friendships were reported by 1,603 adolescents, aged 11-16 years, who participated in the school-based I.Family study in 6 European countries. Each "source child" named 1-10 friends for whom standardized weight-related traits were available in the same survey. The mean value of the friends' traits weighted by time spent together was calculated, and related to the source child's trait. Country, age and sex of the source child, parental education, and immigrant background were considered for confounding and moderation.

RESULTS

Source children's z-scores of body fat percent and BMI were positively associated with their friends' characteristics, in particular if they had highly educated parents. Positive associations were also found regarding the frequency of fast-food consumption, impulsivity, screen time, preference for sugar-sweetened foods, and hours spent in sports clubs, in increasing order of effect size. Additionally, correlations were observed between friends' cognitive and school functioning and being bullied. No associations were seen for a preference for high-fat foods, weight concerns, and health-related quality of life. Finally, parental education and immigrant background were associated between friends in all countries except Sweden, where no associations were observed.

CONCLUSION

Adolescent friends shared a number of weight-related characteristics. For weight measures per se, positive associations with friends' characteristics were only observed in adolescents with high parental education. Associations regarding energy-balance behaviors and indicators of school-related well-being did not differ by parental education. Parental education and immigrant background correlated positively in friends in most countries showing that social aggregation is already occurring in adolescence. The wide spectrum of friendship associations in weight-related traits and behaviors suggests that health promotion initiatives in adolescents should be directed towards peer groups in both school-related and leisure-time environments. ISRCTN Registry: Pan-European IDEFICS/I.Family children cohort (ID ISRCTN62310987; https://doi.org/10.1186/ISRCTN62310987).

Family ties and child obesity in Italy

This paper examines the impact of overweight family members on weight outcomes of Italian children aged 6-14 years. We use an original dataset matching the 2012 cross sections of the Italian Multipurpose Household Survey and the Household Budget Survey. Since the identification of within-family peer effects is known to be challenging, we implement our analysis on a partially identified model using inferential procedures recently introduced in the literature and based on standard Bayesian computation methods. We find evidence of a strong, positive effect of both overweight peer children in the family and of overweight adults on children weight outcomes. The impact of overweight peer children in the household is larger than the impact of adults. In particular, the estimated confidence sets associated to the peer children variable is positive with upper bound around one or larger, while the confidence sets for the parameter associated to obese adults often include zero and have upper bound that rarely is larger than one.

Not only in my genes: The effects of peers' genotype on obesity

We use data from three waves of Add Health to study the short- and long-run effects of high school peers' genetic predisposition to high BMI-measured by grade-mates' average BMI polygenic scores-on adolescent and adult obesity in the U.S. We find that, in the short-run, a one standard deviation increase in peers' average BMI polygenic scores raises the probability of obesity for females by 2.8% points, about half the size of the effect induced by a one standard deviation increase in one's own polygenic score. No significant effect is found for males. In the long-run, however, the social-genetic effect fades away, while the effect of one's own genetic risk for BMI increases substantially. We suggest that mechanisms explaining the short-run effect for females include changes in nutrition habits and a distorted perception of body size.

Does Interpersonal Interaction Really Improve Emotion, Sleep Quality, and Self-Efficacy among Junior College Students?

This study discusses the correlation between teenagers' real-life interpersonal interactions and teenagers' online interpersonal interactions with regards to emotion, sleep quality, and self-efficacy. This study adopted a cross-sectional design that included a survey using a structured questionnaire which included demographic data, the Chinese version of the Depression Anxiety Stress Scale (DASS-21), the Pittsburgh Sleep Quality Index (PSQI), the General Self-Efficacy Scale (GSE), the Real Interpersonal Interaction Scale (RIIS), and the Internet Interpersonal Interaction Scale (IIIS). This study enlisted 917 teenage students (age = 17.16 ± 1.48 years). The study found that RIIS had significant negative correlations with DASS and PSQI scores and a significant positive correlation with GSE. Namely, the greater the degree of real-life interpersonal interaction, the lower the degree of negative emotion. Likewise, the more satisfactory sleep quality is, the higher self-efficacy is. In addition, IIIS scores demonstrate significantly positive correlations with DASS and PSQI scores. Therefore, the greater the degree of online interpersonal interaction, the greater the levels of negative emotion, and the poorer the sleep quality is. This study showed that online interpersonal interaction may not improve emotions, sleep quality, or self-efficacy among junior college students. However, real-life interpersonal interaction may improve those three parameters.

Parental and Peer Support are Associated with Physical Activity in Adolescents: Evidence from 74 Countries

Although parental and peer support can influence adolescents’ physical activity (PA), these associations have not been fully examined through a global assessment. This study examined the associations of parental and peer support with PA among adolescents from 74 countries. The Global School-based Student Health Survey data from 250,317 adolescents aged 11–17 years (48.8% girls), collected between 2007 and 2016, were analysed. Adolescents were asked how many days/week they were physically active and about their parental and peer support. Meta-analysis showed that adolescents who had high parental or peer support had higher odds of attaining sufficient PA (odds ratio (OR): 1.40, 95% confidence interval (CI): 1.34–1.46; OR: 1.57, 95% CI: 1.49–1.65, respectively). Pooled estimates of association were significant across all World Health Organization (WHO) regions and country-income categories with the highest estimate from the low-income countries. The Western Pacific region showed the highest association between parental support and adolescents’ PA (OR: 1.49, 95% CI: 1.41–1.59), while South-East Asia exhibited the highest association between peer support and adolescents’ PA (OR: 1.80, 95% CI: 1.59–2.04). Country-level estimates of associations are presented. Future studies should use robust assessment of PA and PA-specific parental and peer support with emphasis on qualitative investigation to understand the complexity of the relationships.

A Trial of Student Self-Sponsored Peer-to-Peer Lending Based on Credit Evaluation Using Big Data Analysis

There is still no effective approach to overcome the problem of credit evaluation for Chinese students. In absence of a reliable credit evaluation system for students, the university students have to only apply through online peer-to-peer (P2P) loan platforms because Chinese financial institutions typically reject students' loan applications. Lack of students' financial records hinders financial institutes and banks to routinely evaluate the students' credit status and assign loans to them. Hence, this paper attempted to benefit from university students' diversified daily behavior data, and logistic regression (LR) and gradient boosting decision tree (GBDT) algorithms were also used to develop robust credit evaluation models for university students, in which the validation of the proposed models was assessed by a real-time P2P lending platform. In this study, the students' overdue behavior in returning books to university library was used as an index. With training 17838 samples, the proposed models performed well, while GBDT-based model outperformed in identification of “bad borrowers.” Based on the proposed models, a self-sponsored peer-to-peer loan platform was established and developed in a Chinese university for ten months, and the achieved findings demonstrated that adopting such credit evaluation models can effectively reduce the default ratio.

Applications of social network analysis to obesity: a systematic review

People's health behaviours and outcomes can be profoundly shaped by the social networks they are embedded in. Based on graph theory, social network analysis is a research framework for the study of social interactions and the structure of these interactions among social actors. A literature search was conducted in PubMed and Web of Science for articles published until August 2017 that applied social network analysis to examine obesity and social networks. Eight studies (three cross-sectional and five longitudinal) conducted in the US (n = 6) and Australia (n = 2) were identified. Seven focused on adolescents' and one on adults' friendship networks. They examined structural features of these networks that were associated with obesity, including degree distribution, popularity, modularity maximization and K-clique percolation. All three cross-sectional studies that used exponential random graph models found individuals with similar body weight status and/or weight-related behaviour were more likely to share a network tie than individuals with dissimilar traits. Three longitudinal studies using stochastic actor-based models found friendship network characteristics influenced change in individuals' body weight status and/or weight-related behaviour over time. Future research should focus on diverse populations and types of social networks and identifying the mechanisms by which social networks influence obesity to inform network-based interventions.

Breakfast choice: An experiment combining a nutritional training workshop targeting adolescents and the promotion of unhealthy products

A randomised control trial was conducted to determine changes in the food and drink choices of adolescents following their participation in a 50-min nutrition workshop. The experiment was conducted at 104 schools in Barcelona (126 classes, 3,291 adolescents). Schools were randomly selected and stratified by district and by public or private status. The students were given three types of vouchers with different options regarding the type of food for which the vouchers could be exchanged (standard for healthy food and drink, two for one for unhealthy food, and two for one for unhealthy drink). Difference-in-differences linear models that control for individual, family, school or neighbourhood characteristics, and the influence of peers were applied. The probability of students' choosing unhealthy food and drink fell by 7.1% and 4.4%, respectively, following participation in the nutrition workshop. The promotion of unhealthy beverages counteracted the positive impact of the workshop on beverage choice.

Estimating sibling spillovers in health: Evidence on symptoms

This paper estimates the sibling spillover effect in health symptoms using a sample of US adolescents from the National Longitudinal Study of Adolescent Health dataset. The research design of this paper is to restrict the sample to sibling pairs who are separated between schools, where one enters high school and the other middle school. Because of school separation, sibling pairs face independent health shocks from own school peers. The identification strategy further exploits variations in individual health across symptoms to control for unobserved individual heterogeneity, which flexibly partials out family correlated effects. Estimation results show that the sibling spillover effect is large as a one-standard-deviation increase in one sibling's frequency of developing a stomach ache or a loss of appetite increases the other sibling's frequency of having the same symptom by about 55% of a standard deviation. Further investigation suggests that the effect is not due to spillovers in drinking alcohol or depression, but probably due to the spread of contagious illnesses like the stomach flu.

Values, Norms, and Peer Effects on Weight Status

This study uses data from the European Social Survey in order to test the Prinstein-Dodge hypothesis that posits that peer effects may be larger in collectivistic than in individualistic societies. When defining individualism and collectivism at the country level, our results show that peer effects on obesity are indeed larger in collectivistic than in individualistic societies. However, when defining individualism and collectivism with individual values based on the Shalom Schwartz universal values theory, we find little support for this hypothesis.

Peer effects on obesity in a sample of European children

This study analyzes peer effects on childhood obesity using data from the first two waves of the IDEFICS study, which applies several anthropometric and other measures of fatness to approximately 14,000 children aged two to nine participating in both waves in 16 regions of eight European countries. Peers are defined as same-sex children in the same school and age group. The results show that peer effects do exist in this European sample but that they differ among both regions and different fatness measures. Peer effects are larger in Spain, Italy, and Cyprus--the more collectivist regions in our sample--while waist circumference generally gives rise to larger peer effects than BMI. We also provide evidence that parental misperceptions of their own children's weight goes hand in hand with fatter peer groups, supporting the notion that in making such assessments, parents compare their children's weight with that of friends and schoolmates.

Misreporting and misclassification: implications for socioeconomic disparities in body-mass index and obesity

Body-mass index (BMI) has become the standard proxy for obesity in social science research. This study deals with the potential problems related to, first, relying on self-reported weight and height to calculate BMI (misreporting), and, second, the concern that BMI is a deficient measure of body fat (misclassification). Using a regional Swedish sample, we analyze whether socioeconomic disparities in BMI are biased because of misreporting, and whether socioeconomic disparities in the risk of obesity are sensitive to whether BMI or waist circumference is used to define obesity. Education and income are used as socioeconomic indicators. The overall conclusion is that misreporting and misclassification may indeed matter for estimated educational and income disparities in BMI and obesity. In the misreporting part we find that women with higher education misreport less than those with lower education, leading to underestimation of the education disparity when using self-reported information. In the misclassification part we find that the probability of being misclassified decreases with income, for both men and women. Among women, the consequence is a steeper income gradient when obesity is defined using waist circumference instead of BMI. Among men the income gradient is statistically insignificant irrespective of how obesity is defined, but when estimating the probability of obesity defined by waist circumference, an educational gradient, which is not present when classifying men using BMI, arises.