Association of Exposure to Communities With High Obesity With Body Type Norms and Obesity Risk Among Teenagers

Population mobility data provides meaningful indicators of fast food intake and diet-related diseases in diverse populations

The characteristics of food environments people are exposed to, such as the density of fast food (FF) outlets, can impact their diet and risk for diet-related chronic disease. Previous studies examining the relationship between food environments and nutritional health have produced mixed findings, potentially due to the predominant focus on static food environments around people's homes. As smartphone ownership increases, large-scale data on human mobility (i.e., smartphone geolocations) represents a promising resource for studying dynamic food environments that people have access to and visit as they move throughout their day. This study investigates whether mobility data provides meaningful indicators of diet, measured as FF intake, and diet-related disease, evaluating its usefulness for food environment research. Using a mobility dataset consisting of 14.5 million visits to geolocated food outlets in Los Angeles County (LAC) across a representative sample of 243,644 anonymous and opted-in adult smartphone users in LAC, we construct measures of visits to FF outlets aggregated over users living in neighborhood. We find that the aggregated measures strongly and significantly correspond to self-reported FF intake, obesity, and diabetes in a diverse, representative sample of 8,036 LAC adults included in a population health survey carried out by the LAC Department of Public Health. Visits to FF outlets were a better predictor of individuals' obesity and diabetes than their self-reported FF intake, controlling for other known risks. These findings suggest mobility data represents a valid tool to study people's use of dynamic food environments and links to diet and health.

Association of Place With Adolescent Obesity

Importance

Despite strong evidence linking place and obesity risk, the extent to which this link is causal or reflects sorting into places is unclear.

Objective

To examine the association of place with adolescents' obesity and explore potential causal pathways, such as shared environments and social contagion.

Design, Setting, and Participants

This natural experiment study used the periodic reassignment of US military servicemembers to installations as a source of exogenous variation in exposure to difference places to estimate the association between place and obesity risk. The study analyzed data from the Military Teenagers Environments, Exercise, and Nutrition Study, a cohort of adolescents in military families recruited from 2013 through 2014 from 12 large military installations in the US and followed up until 2018. Individual fixed-effects models were estimated that examined whether adolescents' exposure to increasingly obesogenic places over time was associated with increases in body mass index (BMI) and probability of overweight or obesity. These data were analyzed from October 15, 2021, through March 10, 2023.

Exposure

Adult obesity rate in military parent's assigned installation county was used as a summary measure of all place-specific obesogenic influences.

Main Outcomes and Measures

Outcomes were BMI, overweight or obesity (BMI in the 85th percentile or higher), and obesity (BMI in the 95th percentile or higher). Time at installation residence and off installation residence were moderators capturing the degree of exposure to the county. County-level measures of food access, physical activity opportunities, and socioeconomic characteristics captured shared environments.

Results

A cohort of 970 adolescents had a baseline mean age of 13.7 years and 512 were male (52.8%). A 5 percentage point-increase over time in the county obesity rate was associated with a 0.19 increase in adolescents' BMI (95% CI, 0.02-0.37) and a 0.02-unit increase in their probability of obesity (95% CI, 0-0.04). Shared environments did not explain these associations. These associations were stronger for adolescents with time at installation of 2 years or longer vs less than 2 years for BMI (0.359 vs. 0.046; P value for difference in association = .02) and for probability of overweight or obesity (0.058 vs. 0.007; P value for difference association = .02), and for adolescents who lived off installation vs on installation for BMI (0.414 vs. -0.025; P value for association = .01) and for probability of obesity (0.033 vs. -0.007; P value for association = .02).

Conclusion and Relevance

In this study, the link between place and adolescents' obesity risk is not explained by selection or shared environments. The study findings suggest social contagion as a potential causal pathway.

Heterogeneity in place effects on health: The case of time preferences and adolescent obesity

We leverage a natural experiment in combination with data on adolescents' time preferences to assess whether there is heterogeneity in place effects on adolescent obesity. We exploit the plausibly exogenous assignment of military servicemembers, and consequently their children, to different installations to identify place effects. Adolescents' time preferences are measured by a validated survey scale. Using the obesity rate in the assigned installation county as a summary measure of its obesity-related environments, we show that exposure to counties with higher obesity rates increases the likelihood of obesity among less patient adolescents but not among their more patient counterparts.

Social alienation of adolescents with obesity in classrooms: A multilevel approach

INTRODUCTION

Adolescents with obesity are more likely to be isolated by peers, but whether they also choose to disengage from their peers remains unclear.

METHODS

This study examined a sample of 646 adolescents between the age of 13 and 16 across 34 classrooms in 3 junior high schools in Taiwan, with data collected from May to June 2019. The sociometric network nomination method assessed peer relationships, such as unpopularity, unsociability, and alienation. Multilevel models were applied to explore the extent to which the class-level prevalence of overweight and obesity and peer support moderate the relationship between student-level obesity and peer relationships.

RESULTS

Overall, students with obesity were more likely to experience unpopularity, unsociability, and alienation from their peers in classroom settings (adjusted odds ratio [AOR] = 1.904, 2.208, 2.777, p < .05). Regardless of their obesity status, students in high classroom peer support were less likely to report unsociability (AOR = 0.124, p < .05). No cross-level interactions were observed, indicating that students with obesity did not experience a reduction of peer rejection in high peer support classrooms. Neither did obese students in classrooms with higher rates of overweight and obesity.

CONCLUSIONS

Students with obesity were more likely to experience interpersonal problems. Classroom peer support can increase peer acceptance for typical students but has no beneficial influence on adolescents with weight problems. Classroom peer support needs to be directed to become adequate support for students with obesity.

Effects of programs and interventions related to the social environment on childhood and adolescent obesity: A systematic search for and scoping review of natural experiments

Given the potential importance of social environment on obesity and to better understand their causal relationship amongst children and adolescents, this scoping review systematically searches for and evaluates programs and interventions using natural experiment designs. A majority of the studies assessing peer and social norm effects reported significant findings. Peer effects with nontrivial effect sizes likely have practical implications for interventions, while a strong conclusion cannot be drawn for social norm and neighborhood safety effects. Leveraging naturally occurring data might provide future research with a promising way of establishing a more robust causal inference for the topic of interest.