Association of Physical Activity and Screen Time With Body Mass Index Among US Adolescents

Effectiveness of Universal Community Engagement Childhood Obesity Interventions at Improving Weight-Related and Behavioral Outcomes among Children and Adolescents: A Systematic Review and Meta-Analysis

BACKGROUND

Universal community engagement interventions can address childhood obesity.

OBJECTIVES

This review aimed to evaluate the effectiveness of these interventions in improving body mass index (BMI) (primary outcome) as well as dietary choices and activity levels (secondary outcomes) among children and adolescents.

METHODS

Eight electronic databases were searched from inception dates to January 2024. A meta-analysis was conducted using the random-effect model, when appropriate; otherwise, the findings were narratively synthesized. Heterogeneity was determined by the I2 statistics and Cochran's Q chi-squared test. The Cochrane ROB tool and the GRADE approach were used to assess the quality appraisal at the study and outcome levels, respectively.

RESULTS

Twenty-two studies were included in this review. The results showed that these interventions had a limited effect in improving children's standardized BMI (BMI-z) scores post-intervention. A meta-analysis on BMI-z scores showed that the intervention group had a statistically non-significantly lower BMI-z score than the control group (MD = -0.02, 95%CI = [-0.07, 0.03], Z = 0.83, p = 0.40) at immediate post-intervention. It was also reported that universal community engagement interventions had a limited effect in improving children's dietary choices and activity levels. Only the meta-analysis on children's daily sugar-sweetened beverage intake measured using continuous data reported a statistically significant small effect favoring the intervention group (SMD = -0.25, 95%CI = [-0.38, -0.13], Z = 3.98, p < 0.0001) at immediate post-intervention.

CONCLUSIONS

Universal community engagement interventions have the potential to address childhood obesity. Children and adolescents could benefit more from interventions that focus on implementing both environmental and behavioral changes, and interventions that include parental involvement.

Exploring the Effect of an Obesity-Prevention Intervention on Various Child Subgroups: A Post Hoc Subgroup Analysis of the Kiel Obesity Prevention Study

BACKGROUND

This study investigated potential subgroups of children within the Kiel Obesity Prevention Study (KOPS) for differing treatment effects for the outcome measures of overweight or obesity at 4 years. The KOPS study delivered a multicomponent school intervention to cohorts of children in Kiel but found no overall effect on the weight status outcome. However, KOPS authors suggested there may be subgroup variations in treatment effect. Data were collected as part of the KOPS for samples of 6-year-olds between 1996 and 2001, with 4-year follow-up measurements between 2000 and 2004.

METHODS

The present study conducted a post hoc subgroup analysis of the odds of obesity or overweight at 4-year follow-up compared to normal weight (n = 1646). A generalized linear mixed-effects model, including a treatment-subgroup interaction term, was used to estimate subgroups as a moderator of the treatment effects on the outcomes of obesity or overweight at 4-year follow-up.

RESULTS

The findings indicated several subgroup-treatment interaction effects relating to physical activity indicators. TV or PC not being one of a child's top 3 activities at baseline was associated with a significantly decreased odds ratio of obesity at 4 years in the intervention group (OR, 0.04; 95% CI, 0.004 to 0.45) compared to the non-intervention group (OR, 0.96; 95% CI, 0.29 to 3.14), p = 0.02. Weekly activity in a sports club at baseline was associated with a decreased odds ratio of overweight at 4 years in the intervention group (OR, 0.38; 95% CI, 0.16 to 0.85) compared to the non-intervention group (OR, 0.91; 95% CI, 0.70 to 1.17). This was a significant difference (p = 0.04).

CONCLUSIONS

These findings suggest that children's baseline physical activity may impact treatment effects on the outcomes of overweight and obesity, creating opportunities to increase the effectiveness of interventions on preventing obesity.

Fundamental movement skills proficiency in preschool-aged boys and girls: Family matters

To investigate the associations of fundamental movement skill (FMS) proficiency with family factors, including socioeconomic status (SES) and caregiver characteristics, by sex in young children in China. Participants included 1,207 Chinese children aged 3-6 years in this cross-sectional study. Children's FMS, consisting of locomotor skills and object control (OC) skills, were assessed. Information on family SES and caregiver characteristics was reported by the parents. Sex differences in outcomes and the associations of FMS with family factors by sex were examined using SPSS 26.0. Boys scored significantly higher than girls in terms of overall FMS and OC skills (both p < 0.01). There were significant and negative associations between children's FMS and parental education level and parental body mass index (BMI), which varied by sex. Boys who were regularly cared for by parents had higher FMS and OC skill scores than did those who were primarily looked after by grandparents (both p < 0.01). This complex interplay between sex and family factors (i.e. parental education level, parental BMI, and the identity of primary caregiver) on FMS proficiency in young children underscores the urgent need for developing sex-tailored, family-involved, and socio-culturally adapted interventions to enhance FMS proficiency at the preschool stage.

Independent and Combined Associations of Physical Activity and Screen Time With Biomarkers of Inflammation in Children and Adolescents With Overweight/Obesity

PURPOSE

Inflammation regulation is important for obesity management and prevention of obesity-related diseases. This cross-sectional study aimed to analyze the independent and combined associations of physical activity and screen time with biomarkers of inflammation in children and adolescents with overweight/obesity.

METHOD

A total of 1289 children and adolescents with overweight/obesity were included from the 2015 to 2018 National Health and Nutrition Examination Survey. Multivariable linear regressions were conducted for the association analyses.

RESULTS

For the independent associations, a negative dose-dependent relationship was demonstrated between physical activity and inflammatory biomarker high-sensitivity C-reactive protein (hsCRP) in adolescents with overweight/obesity (P < .001) but not children; screen time was not associated with hsCRP in both children and adolescents. No significant association was found between physical activity or screen time with other inflammatory biomarkers. For the combined associations, there was an interaction between physical activity and screen time on hsCRP in adolescents with overweight/obesity (P = .014). In addition, the negative association between physical activity and hsCRP was greater in boys compared with girls and in Hispanic and non-Hispanic Black individuals compared with non-Hispanic White individuals.

CONCLUSION

This study demonstrated a combined association of physical activity and screen time with inflammatory biomarker hsCRP in adolescents with overweight/obesity.

Association of physical activity and screen time with cardiovascular disease risk in the Adolescent Brain Cognitive Development Study

BACKGROUND

According to the Physical Activity Guidelines Advisory Committee Scientific Report, limited evidence is available on sedentary behaviors (screen time) and their joint associations with physical activity (steps) for cardiovascular health in adolescence. The objective of this study was to identify joint associations of screen time and physical activity categories with cardiovascular disease (CVD) risk factors (blood pressure, hemoglobin A1c, cholesterol) in adolescence.

METHODS

This study analyzed data from the Adolescent Brain Cognitive Development (ABCD) Study, comprising a diverse sample of 4,718 U.S. adolescents aged 10-15 years between 2018 and 2021. Steps were measured by a Fitbit wearable device and levels were categorized as low (1,000-6,000), medium (> 6,000-12,000), and high (> 12,000) averaged daily step counts. Self-reported recreational screen time hours per day were classified as low (0-4), medium (> 4-8), and high (> 8) hours per day. CVD risk factors including blood pressure, hemoglobin A1c, and cholesterol (total and HDL) were measured.

RESULTS

The analytical sample averaged 6.6 h of screen time per day and 9,722 steps per day. In models including both screen time and steps, the high screen time category was associated with a 4.27 higher diastolic blood pressure percentile (95% CI 1.83-6.73) and lower HDL cholesterol (B= -2.85, 95% CI -4.77 to -0.94 mg/dL) compared to the low screen time category. Medium (B = 3.68, 95% CI 1.24-6.11) and low (B = 7.64, 95% CI 4.07-11.20) step categories were associated with higher diastolic blood pressure percentile compared to the high step category. The medium step category was associated with lower HDL cholesterol (B= -1.99, 95% CI -3.80 to -0.19 mg/dL) compared to the high step category. Findings were similar when screen time and step counts were analyzed as continuous variables; higher continuous step count was additionally associated with lower total cholesterol (mg/dL).

CONCLUSIONS

Combinations of low screen time and high steps were generally associated with favorable cardiovascular health markers including lower diastolic blood pressure and higher HDL cholesterol, which can inform future adolescent health guidelines.

National Trends in the Prevalence of Screen Time and Its Association With Biopsychosocial Risk Factors Among Korean Adolescents, 2008-2021

PURPOSE

Prior studies suggested an increase in screen time among adolescents during the COVID-19 pandemic; however, due to limited sample size and a short-term observation period, these associations are inconclusive and inconsistent. Thus, we aimed to compare screen time during the pandemic and the long-term trend through a Korean large-scale and long-term study of one million adolescents.

METHODS

Data from 2008 to 2021 on 913,191 Korean adolescents aged 12-18 years were obtained via a nationwide, large-scale, and serial study. We investigated the change of screen time use over time and the change in trend before and during the pandemic (2008-2019 vs. 2020-2021) by using weighted linear regression model with estimates of β-coefficients and 95% confidence intervals (CIs). Moreover, we analyzed the differences in vulnerability of biopsychosocial factor before and during the pandemic.

RESULTS

A total of 913,191 adolescents were included in this analysis. During the pandemic, the overall screen time of Korean adolescents significantly increased compared to the expected based on the prepandemic period during the pre-COVID-19 period (weighted screen time before the pandemic [133.24 min/day; 95% CI, 132.08-134.40] vs. during the pandemic [303.66 min/day; 95% CI, 300.59-306.73]; βdiff 0.331; 95% CI, 0.311-0.351). Comparing before and during the pandemic, potential risk factors associated with screen exposure included female sex, sadness, suicidal thoughts, alcohol consumption, low educational level of parents, low level of vigorous physical activity, middle school students, and low household income.

DISCUSSION

Through large-scale nationwide study, this study described the 14-year trend of screen time among Korean adolescents. In the era of COVID-19, the prevalence of screen exposure has been increasing more rapidly than before at the population level. Also, the pandemic amplified the differences in screen time across grade, sex, sadness, suicidal thoughts, smoking, alcohol consumption, education level of parents, physical activity, and household income groups.

Self-reported and tracked nighttime smartphone use and their association with overweight and cardiometabolic risk markers

Nighttime smartphone use is associated with sleep problems, which in turn have a bidirectional association with overweight. We aim to investigate whether nighttime smartphone use and sleep are related to overweight and metabolic dysfunction in adult populations. We used data from three population samples (aged 16-89) from the SmartSleep Study, which included survey data (N = 29,838), high-resolution tracking data (N = 3446), follow-up data (N = 1768), and cardiometabolic risk markers (N = 242). Frequent self-reported nighttime smartphone use was associated with 51% higher odds (95% CI: 1.32; 1.70) of overweight compared with no use. Tracked nighttime smartphone use was also associated with overweight. Similar results were found for obesity as an outcome. No consistent associations were found between nighttime smartphone use and cardiometabolic risk markers in a small subsample of healthy young women. Poor sleep quality (vs. good sleep quality) was associated with overweight (OR = 1.19, 85% CI: 1.10; 1.28). Overall, frequent nighttime smartphone use was consistently associated with overweight and a higher BMI across diverse population samples. The bidirectional interplay between nighttime smartphone use, sleep, and overweight may create a vicious circle of metabolic dysfunction over time. Therefore, nighttime smartphone use may be a potential target point for public health interventions to reduce overweight at the population level.

Motivation for Physical Activity as a Key Determinant of Sedentary Behavior Among Postsecondary Students

It is known that the transition to adulthood represents a critical period of life when acquiring healthy behaviors can influence lifestyle and health throughout adulthood. Given the importance of the consequences of a sedentary lifestyle, identifying influence factors is key to improving healthy behaviors. The objective of this study is to explore the role of postsecondary students' motivation toward physical activity in the association with their screen time and out-of-school physical activity practice. A total of 1522 postsecondary students (90% were aged 17-20 years) recruited from 17 postsecondary institutions completed the self-reported questionnaire during course time. Multivariate linear regression was used to assess the association between motivation to move including additional predictors of behavior such as intention and tendency to self-activate and self-reported screen time and physical activity controlling for age and sex. Motivation including all 3 motivational variables (interest, utility, competence) was negatively associated with screen time, b = -0.498 (95% CI between -0.635 and -0.361) and positively associated with moderate-to-vigorous physical activity, b = 133.986, (95% CI between 102.129 and 165.843). Of the 3 motivational variables, interest had the strongest negative association with screen time, b = -0.434 (95% CI between -0.551 and -0.317), and the strongest positive association with physical activity, b = 113.671, (95% CI between 86.396 and 140.946). These findings indicate that the motivation of postsecondary students toward physical activity significantly influences their behaviors, including screen time and physical activity engagement.

Dietary and Lifestyle Risk Factors of Obesity Among Young Adults: A Scoping Review of Observational Studies

PURPOSE OF REVIEW

Obesity is a growing public health concern worldwide, especially among young adults. This scoping review aims to identify and summarize the current evidence on dietary and lifestyle risk factors associated with obesity among young adults.

RECENT FINDINGS

A scoping review was performed using the PRISMA-ScR guidelines. A systematic search of five electronic databases published from inception to October 2023 was conducted. A total of 46 observational studies met the inclusion criteria and were included in the review. The findings suggest that high intake of energy-dense foods, unhealthy eating habits, poor sleep quality, and increased screen time were significant risk factors for obesity among young adults. In contrast, the association between obesity and sedentary behavior, low physical activity levels, alcohol consumption, and smoking habits was inconclusive. The reviewed evidence suggests that unhealthy dietary habits and lifestyle behaviors are associated with an increased risk of obesity among young adults. The findings highlight the need for further research on these modifiable risk factors to prevent and manage obesity among young adults.

Perceptions of Parental Support for Physical Activity and Healthy Eating among School-age Children During COVID-19 pandemic

Family routines play a key role in promoting child health behaviors. This study 1) describes changes in children's perceptions of physical activity (PA) and healthy eating family routines across three time points: pre-pandemic (2017-2020), early pandemic (2020), and mid-pandemic (2021); and 2) explores how sex, age, and pandemic-related economic stressors relate to changes. Children's perceptions of family routines were assessed using four subscales adapted from the Comprehensive Home Environment Survey: PA-policies, Diet-policies, Diet-rules, and PA-Diet-role-model. Linear mixed models assessed changes in perceptions and associated factors (child age and sex; caregiver(s) job loss during pandemic). Children (N=277) were aged 9.3-15.5y at pandemic onset (March 2020), dichotomized by median age (12.1y) as younger and older. Children's perceptions of PA-policies (pre-pandemic mean=15.4) and Diet-policies (pre-pandemic mean=26.3) increased significantly from pre- to early (b=1.2 and 2.3, respectively) and mid-pandemic (b=1.0 and 1.2, respectively). Diet-rules (pre-pandemic mean=10.8) decreased significantly from pre- to early (b=-1.1) and mid-pandemic (b=-2.0), with no PA-Diet-role-model changes. Younger children had a greater increase in perceived PA-policies and Diet-policies across the pandemic. Females (59.9%) had a greater decrease in perceived Diet-rules across the pandemic and less increase in Diet-policies and PA-Diet-role-model from pre- to early pandemic. Children whose caregiver(s) lost employment (51.8%) perceived a greater increase in PA-policies. Overall, children reported increased parental policies to support PA and healthy eating and decreased parental rules for diet during the pandemic. Future research is needed to understand how changes in family routines relate to PA and healthy eating behaviors.

Overweight/Obesity-related microstructural alterations of the fimbria-fornix in the ABCD study: The role of aerobic physical activity

Childhood overweight/obesity has been associated with negative consequences related to brain function and may involve alterations in white matter pathways important for cognitive and emotional processing. Aerobic physical activity is a promising lifestyle factor that could restore white matter alterations. However, little is known about either regional white matter alterations in children with overweight/obesity or the effects of aerobic physical activity targeting the obesity-related brain alterations in children. Using a large-scale cross-sectional population-based dataset of US children aged 9 to 10 years (n = 8019), this study explored the associations between overweight/obesity and microstructure of limbic white matter tracts, and examined whether aerobic physical activity may reduce the overweight/obesity-related white matter alterations in children. The primary outcome measure was restriction spectrum imaging (RSI)-derived white matter microstructural integrity measures. The number of days in a week that children engaged in aerobic physical activity for at least 60 minutes per day was assessed. We found that females with overweight/obesity had lower measures of integrity of the fimbria-fornix, a major limbic-hippocampal white matter tract, than their lean peers, while this difference was not significant in males. We also found a positive relationship between the number of days of aerobic physical activity completed in a week and integrity measures of the fimbria-fornix in females with overweight/obesity. Our results provide cross-sectional evidence of sex-specific microstructural alteration in the fimbria-fornix in children with overweight/obesity and suggest that aerobic physical activity may play a role in reducing this alteration. Future work should examine the causal direction of the relationship between childhood overweight/obesity and brain alterations and evaluate potential interventions to validate the effects of aerobic physical activity on this relationship.

Association of Racial Discrimination With Adiposity in Children and Adolescents

Importance

Childhood obesity is a major public health issue and is disproportionately prevalent among children from minority racial and ethnic groups. Personally mediated racism (commonly referred to as racial discrimination) is a known stressor that has been linked to higher body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) in adults, but little is known about the association of racial discrimination and childhood and adolescent adiposity.

Objective

To assess the prospective association between self-reported experiences of racial discrimination and adiposity (BMI and waist circumference) in a large sample of children and adolescents in the Adolescent Brain Cognitive Development (ABCD) study.

Design, Setting, and Participants

This cohort study used complete data from the ABCD study (2017 to 2019), involving a total of 6463 participants. The ABCD study recruited a diverse sample of youths from across the US, with rural, urban, and mountain regions. Data were analyzed from January 12 to May 17, 2023.

Exposure

The child-reported Perceived Discrimination Scale was used to quantify racial discrimination, reflecting participants' perceptions of being treated unfairly by others or unaccepted by society based on their race or ethnicity.

Main Outcomes and Measures

Weight, height, and waist circumference were measured by trained research assistants. BMI z scores were computed by applying the US Centers for Disease Control and Prevention's age and sex-specific reference standards for children and adolescents. Waist circumference (inches) was quantified as the mean of 3 consecutive measures. Measurements were taken from time 1 (ie, 2017 to 2019) and time 2 (ie, 2018 to 2020).

Results

Of the 6463 respondents with complete data, 3090 (47.8%) were female, and the mean (SD) age was 9.95 (0.62) years. Greater racial discrimination exposure at time 1 was associated with higher BMI z score in both unadjusted (β, 0.05; 95% CI, 0.02-0.08) and adjusted regression models (β, 0.04; 95% CI, 0.01-0.08). Discrimination at time 1 was associated with higher waist circumference in unadjusted (β, 0.35; 95% CI, 0.15-0.54) and adjusted (β, 0.24; 95% CI, 0.04-0.44) models.

Conclusions and Relevance

In this cohort study of children and adolescents, racial discrimination was positively associated with adiposity, quantified by BMI z score and waist circumference. Interventions to reduce exposure to racial discrimination in early life may help reduce the risk of excess weight gain across throughout life.