Prevalence and trends in obesity among China's children and adolescents, 1985-2010

Interaction between adolescent sleep rhythms and gender in an obese population

BACKGROUND

The obesity rate of adolescents is gradually increasing, which seriously affects their mental health, and sleep plays an important role in adolescent obesity.

AIM

To investigate the relationship between sleep rhythm and obesity among adolescents and further explores the interactive effect of sleep rhythm and gender on adolescent obesity, providing a theoretical basis for developing interventions for adolescent obesity.

METHODS

Research data source Tianjin Mental Health Promotion Program for Students. From April to June 2022, this study selected 14201 students from 13 middle schools in a certain district of Tianjin as the research subject using the convenient cluster sampling method. Among these students, 13374 accepted and completed the survey, with an effective rate of 94.2%.The demographic data and basic information of adolescents, such as height and weight, were collected through a general situation questionnaire. The sleep rhythm of adolescents was evaluated using the reduced version of the morningness-eveningness questionnaire.

RESULTS

A total of 13374 participants (6629 females, accounting for 49.56%; the average age is 15.21 ± 1.433 years) were analyzed. Among them, the survey showed that 2942 adolescent were obesity, accounting for 22% and 2104 adolescent were overweight, accounting for 15.7%. Among them, 1692 male adolescents are obese, with an obesity rate of 25.1%, higher than 18.9% of female adolescents. There is a statistically significant difference between the three groups (χ2 = 231.522, P < 0.000). The obesity group has the smallest age (14.94 ± 1.442 years), and there is a statistical difference in age among the three groups (F = 69.996, P < 0.000).Obesity rates are higher among individuals who are not-only-child, have residential experience within six months, have family economic poverty, and have evening-type sleep (P < 0.05). Logistic regression analysis shows a correlation between sleep rhythm and adolescent obesity. Evening-type sleep rhythm can increase the risk of obesity in male adolescents [1.250 (1.067-1.468)], but the effect on female obesity is not remarkable. Further logistic regression analysis in the overall population demonstrates that the interaction between evening-type sleep rhythm and the male gender poses a risk of adolescent obesity [1.122 (1.043-1.208)].

CONCLUSION

Among adolescents, the incidence of obesity in males is higher than in females. Evening-type sleep rhythm plays an important role in male obesity but has no significant effect on female obesity. Progressive analysis suggests an interactive effect of sleep rhythm and gender on adolescent obesity, and the combination of evening-type sleep and the male gender promotes the development of adolescent obesity. In formulating precautions against adolescent obesity, obesity in male adolescents with evening-type sleep should be a critical concern.

Understanding the Knowledge, Attitudes, and Practices of Healthy Eating among Adolescents in Chongqing, China: An Empirical Study Utilizing Structural Equation Modeling

Healthy eating is crucial for optimal growth, development, and the prevention of chronic diseases in adolescents. Our study aimed to develop a comprehensive structural equation model (SEM) to analyze the relationships between knowledge, attitudes, practices (KAP), and healthy eating among adolescents in Chongqing. An online questionnaire was administered to middle school students in 39 districts and counties of Chongqing, China from 2 December to 15 December 2021 to collect sociodemographic and KAP information. SEM models were constructed to examine the relationships between educational environment and healthy eating knowledge, attitudes, and practices. The Monte Carlo test was employed to assess the significance of the mediating effect of relevant variables. The study included 139,832 adolescents aged 14.8 ± 0.7 years, with a 14% rate of overweight and obesity. Health and nutrition knowledge averaged a score of 3.60 ± 1.50 (correct rate: 60%). Participants had positive attitudes (average score: 13.61 ± 2.29) and engaged in healthy eating practices (average score: 12.06 ± 3.08). The results of the SEM revealed a significant influence of the educational environment on adolescents' knowledge (β = 0.235, p < 0.001) and attitude towards healthy eating (β = 0.143, p < 0.001). Knowledge exhibited positive effects on both attitude (β = 0.225, p < 0.001) and practice (β = 0.054, p < 0.001), while attitude exhibited positive effects on practice behavior (β = 0.565, p < 0.001). The indirect effect of knowledge on practices through attitude was more substantial than the direct effect (ratio 2.361). Our study highlights the mediating role of attitude between healthy eating knowledge and practices. A significant association exists between a favorable educational environment and improved knowledge and positive attitudes toward healthy eating among adolescents. In the future, nutrition and health education should prioritize exploring effective ways to translate knowledge into practices.

Rapid increases in BMI waist to height ratio during adolescence and subsequent neurobehavioral deficits

OBJECTIVE

The aim of this study was to explore prospective relationships between changing patterns of BMI/waist to height ratio (WHtR) during adolescence and subsequent neurobehavioral development.

METHODS

In this prospective cohort study, randomized stratified sampling was used to recruit six middle schools and 609 students in Shanghai, China. In Grades 6, 7, and 9, the Youth Self Report scale was used to assess student neurobehavioral status and anthropometric measurements were conducted to calculate BMI z scores and WHtRs. Longitudinal data were analyzed using latent class mixture modeling to delineate trajectories of BMI z scores ("stable," "decreasing," "rapidly increasing") and WHtRs ("stable," "rapidly increasing"), and their associations with neurobehavioral status in Grade 9 were assessed.

RESULTS

In Grades 6 through 9 (ages 11-15 years), the prevalence of overall obesity and abdominal obesity ranged from 10.7% to 13.0% and 13.0% to 19.8%, respectively. Compared with the stable BMI z score trajectory, the rapidly increasing BMI z score trajectory was longitudinally associated with delinquent behavior, aggressive behavior, and externalizing problems (incidence rate ratio: 1.564-1.613, adjusted p < 0.05). Compared with the stable WHtR trajectory, the rapidly increasing WHtR trajectory significantly predicted increased risks of social problems and delinquent behavior (incidence rate ratios: 1.776-1.967, adjusted p < 0.05). Significant associations of the rapidly increasing BMI z score/WHtR trajectories with subsequent neurobehavioral deficits were observed among girls (adjusted p < 0.05) but not among boys (adjusted p > 0.05).

CONCLUSIONS

Rapid increases in BMI or WHtR during adolescence could predict subsequent neurobehavioral deficits, especially for externalizing behaviors. Timely intervention for weight control may be considered to promote adolescent mental health.

Exploring the impact of water, sanitation and hygiene (WASH), early adequate feeding and access to health care on urban-rural disparities of child malnutrition in China

To explore the effects of UNICEF-suggested modifiable factors, that is, water, sanitation and hygiene (WASH), early adequate feeding and health care on child malnutrition, and to examine the extent to which each factor contributes to urban-rural disparities of child malnutrition in China. Pooling two waves of regionally representative survey data from Jilin, China, in 2013 and 2018, we report on urban-rural relative risks (RRs) in the prevalence of child stunting, wasting and overweight. We employ Poisson regression to examine the effects of urban-rural setting and the three modifiable factors on the prevalence of each malnutrition outcome, that is, stunting, wasting and overweight. We perform mediation analyses to estimate the extent to which each modifiable factor could explain the urban-rural disparities in each malnutrition outcome. The prevalence of stunting, wasting and overweight were 10.9%, 6.3% and 24.7% in urban, and 27.9%, 8.2% and 35.9% in rural Jilin, respectively. The rural to urban crude RR was 2.55 (95% confidence interval [CI]: 1.92-3.39) for stunting, while the corresponding RRs for wasting and overweight were 1.31 (95% CI: 0.84-2.03) and 1.45 (95% CI: 1.20-1.76), respectively. The rural to urban RR for stunting reduced to 2.01 (95% CI: 1.44-2.79) after adjusting for WASH. The mediation analyses show that WASH could mediate 23.96% (95% CI: 4.34-43.58%) of the urban-rural disparities for stunting, while early adequate feeding and health care had no effects. To close the persistent urban-rural gap in child malnutrition, the specific context of rural China suggests that a multi-sectoral approach is warranted that focuses on the sanitation environment and other wider social determinants of health.

Weight self-misperception and obesity-related knowledge, attitudes, lifestyle behaviours and cardio-metabolic markers among Chinese school-aged children and adolescents

OBJECTIVE

The relationships between childhood weight self-misperception and obesity-related factors particularly health markers have not been extensively discussed. This study aims to examine the associations between weight self-misperception and obesity-related knowledge, attitudes, lifestyles and cardio-metabolic markers among Chinese paediatric population.

DESIGN

Cross-sectional study.

SETTING

Data sourced from a national survey in Chinese seven provinces in 2013.

PARTICIPANTS

Children and adolescents aged 5-19 years.

RESULTS

Of the total 14 079 participants, there were 14·5 % and 2·2 % participants over-estimated and under-perceived their weight, respectively. Multi-variable logistic regression was applied to calculate OR and 95 % CI (95 % Cl) of obesity-related behaviours and cardio-metabolic markers by actual and perceived weight status. Individuals who perceived themselves as overweight/obese were more likely to have prolonged screen time, insufficient dairy intake and over sugar-sweetened beverages consumption (all P < 0·05), regardless of their weight. Furthermore, actual overweight/obese individuals had higher odds of abnormal cardio-metabolic markers, but a smaller magnitude of association was found among weight under-estimators. Among non-overweight/obese individuals, weight over-estimation was positively associated with abdominal obesity (OR: 10·49, 95 % CI: 7·45, 14·76), elevated blood pressure (OR: 1·30, 95 % CI: 1·12, 1·51) and dyslipidemia (OR: 1·43, 95 % CI: 1·29, 1·58).

CONCLUSIONS

Weight over-perception was more prevalent than under-estimation, particularly in girls. Weight over-estimators tended to master better knowledge but behave more unhealthily; both weight over-perception and actual overweight/obesity status were associated with poorer cardio-metabolic markers. Future obesity intervention programmes should additionally pay attention to the population with inaccurate estimation of weight who were easily overlooked.

Children who appeared or remained overweight or obese predict a higher follow-up blood pressure and higher risk of hypertension: a 6-year longitudinal study in Yantai, China

Few longitudinal studies have examined the effect of weight status change on blood pressure change over time and incidence of hypertension among Chinese children. The longitudinal study enrolled 17,702 Chinese children aged 7 years in Yantai in 2014 as baseline, with a continuous 5 years of follow-up to 2019. Generalized estimating equation model was fitted to examine the main and interaction effects of weight status change and time with blood pressure and the incidence of hypertension. Compared with the participants who remained normal weight, the participants who remained overweight or obese had higher systolic blood pressure (SBP) (β = 2.89, p < 0.001) and diastolic blood pressure (DBP) (β = 1.79, p < 0.001). Significant interactions were identified between weight status change and time with SBP (χ2interaction = 697.77, p < 0.001) and DBP (χ2interaction = 270.49, p < 0.001). The odds ratio (OR) and 95% confidence interval (CI) of hypertension were 1.70 (1.59-1.82) for participants who appeared overweight or obese, 2.26 (2.14-2.40) for participants who remained overweight or obese, compared with the participants who remained normal weight. Those who switched from overweight or obesity to normal weight had almost the same risk of developing hypertension (OR = 1.13, 95% CI: 1.02 to 1.26) as children who remained normal weight. Children who appeared or remained overweight or obese predict a higher follow-up blood pressure and higher risk of hypertension, whereas losing weight could reduce blood pressure and the risk of hypertension. Children who appeared or remained overweight or obese predict a higher follow-up blood pressure and higher risk of hypertension, whereas losing weight could reduce blood pressure and the risk of hypertension.

Associations of parental feeding practices with children's eating behaviors and food preferences: a Chinese cross-sectional study

BACKGROUND

Childhood inadequate eating behaviors contribute to the epidemic of obesity. Previous research suggests that parental feeding practices are partially associated with development of eating behaviors among children, but the results are inconsistent. The present study was to investigate whether parental feeding practices were associated with eating behaviors and food preferences among Chinese children.

METHODS

A cross-sectional study was conducted to collect data from 242 children (ages 7-12) in six-primary schools in Shanghai, China. A series of questionnaires including parental feeding practices and children's eating behaviors have been validated, and were completed by one of parent who has responded for child's daily diet and living. In addition, researchers instructed children to complete the questionnaire of food preference. After adjustment for children's age, sex and BMI status, as well as parental education and family income, the linear regression analysis was used to evaluate relationships of parental feeding practices with children's eating behaviors and food preferences.

RESULTS

Parents with boys had higher level of control overeating practice than those with girls. Mothers who responded to child's daily diet and living and completed feeding practices questionnaire used a greater level of emotional feeding practices than fathers. Boys had higher levels of food responsiveness, emotional overeating, enjoyment of food and desire to drink than girls. Boys had different preferences for meat, processed meat products, fast foods, dairy foods, eggs, and snacks and starchy staples & beans from girls. In addition, scores of instrumental feeding practice and preference for meat significantly differed among children with different weight status. Furthermore, parental emotional feeding practice was positively associated with children's emotional undereating (β 0.54, 95% CI 0.16 to 0.92). There were also positive associations of parental encouragement to eat with children's preference for the processed meat (β 0.43, 95% CI 0.08 to 0.77). Moreover, instrumental feeding practice was negatively associated with children's fish liking (β -0.47, 95% CI -0.94 to -0.01).

CONCLUSION

The current findings support associations of emotional feeding practice with some children's emotional undereating, as well as parental encouragement to eat and instrumental feeding practice related to preference for processed meat and fish, respectively. Further studies should continue to ascertain these associations using longitudinal designs, and to evaluate efficacy of parental feeding practices impacting developments of healthy eating behaviors and preferences for healthy foods among children by interventional studies.

Longitudinal effects of school policies on children's eating behaviors and weight status: findings from the childhood obesity study in China megacities

OBJECTIVES

To examine longitudinal effects of school policies on children's weight status and eating behaviors, and study how these effects may vary by children's age, sex, and baseline weight status in China.

METHODS

Data were collected in 2015, 2016, and 2017 in an open cohort of 3298 children aged 6-17, their parents, and schools in five large cities across China (Beijing, Shanghai, Xi'an, Nanjing, and Chengdu). Children's weight, height, and waist circumference were measured, and their eating behaviors were self-reported. The 1691 children with such repeated measures in ≥ two waves were included in longitudinal data analysis with mixed effects models, testing the associations.

RESULTS

Having school vicinity food stall policy was associated with less frequent consumption of fast food (β = -0.14, p < 0.01) and snack (β = -0.84, p < 0.01). More significant associations were found between school policies and unhealthy eating behaviors for girls and children aged 6-11 than their counterparts. Among children without overweight or central obesity at baseline, having school cafeteria food policy was associated with lower risks for overweight and obesity (OR = 0.33, 95% CI: 0.17-0.63) and central obesity (OR = 0.47, 95% CI: 0.26-0.85). This existed for girls, but not for boys. School vicinity food stall policy was associated with lower BMI (β = -0.20, 95% CI: -0.37, -0.03) among all children and in girls (β = -0.28, 95% CI: -0.50, -0.05) without overweight at baseline.

CONCLUSIONS

School policies could reduce children's unhealthy eating behaviors and obesity risk in megacities in China. Children's age, sex, and baseline weight status modify the effects. School policies are important to fight the growing childhood obesity epidemic.

Secular trends of the prevalence of emaciation, overweight, and obesity among school-aged children in Yunnan province, 1985–2019: A serial cross-sectional surveillance study in China

Objective

To understand the trends of nutrition in children and adolescents, which may further help to prevent and control chronic diseases in younger ages.

Methods

The Chinese National Surveys on Students' Constitution and Health (CNSSCH) in Yunnan is a survey of growth conditions, physical fitness, and health status of students in Yunnan and uses a series of complex multistage stratified sampling of seven prefectures consisting of 16 counties. Sampling schools were held constant over 35 years. The participants were randomly selected among 7–18 aged students. We used data from 1985, 1991, 2000, 2005, 2010, 2014, and 2019 CNSSCH of Yunnan. According to body mass index (BMI) criteria of National Working Group for Obesity in China (WGOC-BMI criteria), a participant's nutrition (emaciation, overweight or obesity) was defined. This study is based on survey data from 129,520 participants in 1985 (n = 14,683), 1991 (n = 4,894), 1995 (n = 6,673), 2000 (n = 9,751), 2005 (n = 23,461), 2010 (n = 22,889), 2014 (n = 23,003) and 2019 (24,166).

Results

Since 1985, the trends of emaciation over 35 years were decreasing. Regardless of gender, area, and age, the prevalence of obesity and overweight were increased. The average annual growth rate of overweight and obesity was quicker in rural areas and boys than in urban areas and girls. In Yunnan, emaciation, overweight, and obesity disparity in children were common phenomena, with differences in areas and gender.

Conclusion

Children in Yunnan faced the triple burden of malnutrition (emaciation, overweight, and obesity). We should take comprehensive policies and effective intervention measures to decrease the rate of nutrition deficiencies in school-aged children.

Nutritional status, food consumption, lifestyle, and physical fitness in rural and urban elementary school children in Northeast China

Childhood obesity is observed not only in developed countries but also in some developing countries in Asia, where low physical activity and poor physical fitness have been reported. The primary goal of weight loss is to reduce body fat mass, thereby reducing the risk of metabolic syndrome. Unfortunately, a concomitant decrease in lean mass, including muscle mass, is often observed when weight is lost. This study aimed to clarify the nutritional status and physical fitness of local elementary school children and to investigate the factors associated with nutritional status. This study evaluated measures that can reduce the tendency toward obesity and recommends exercise that can reduce weight while maintaining or increasing muscle strength. A total of 911 elementary school children were recruited for this study. All the participants completed anthropometric measurements, dietary surveys, and physical fitness tests. Compared with the Chinese obesity criteria, the proportions of obese and overweight subjects were generally high [22 (rural girls) to 47% (urban boys)], and urban children had a higher obesity rate than rural children. Overall, rural children had better physical fitness test results than urban children did. Skipping rope was correlated with muscle mass. Exercise time (β = -0.31, p < 0.01), skipping rope (β = -0.25, p < 0.01), screen time (β= 0.23, p < 0.01); sit-ups (β = -0.20, p < 0.01); 400-m run (β = -0.19, p < 0.01); urban or rural area (β = 0.18, p < 0.01); oil intake (β = 0.15, p < 0.01), family income (β = 0.11, p < 0.05); and sex (β = -0.10, p < 0.05) were significant predictive factors for overweight and obesity, respectively. The diet of schoolchildren can be improved by reducing the intake of grain and edible oils. Physical fitness of schoolchildren can be improved by increasing exercise time and selecting exercises with higher metabolic equivalents. Rope skipping appears to be the best option because it can ameliorate obesity by increasing muscle strength. The results of this study can provide a reference for the development of obesity intervention methods for children in China and worldwide.

The Interactive Role of Family Functioning among BMI Status, Physical Activity, and High-Fat Food in Adolescents: Evidence from Shanghai, China

Objectives: Family functioning (FF), physical activity (PA), and high-fat food consumption (HF) are associated with adolescents being overweight and obese; however, little is known about their interactions. Therefore, this study aimed to examine how they work jointly on adolescent obesity with BMI as the outcome variable. Methods: A cross-sectional survey utilizing a cluster sampling design was conducted. Multinomial logistic regressions, multiplication interaction (MI), and marginal effects (MEs) were tested. Results: Active PA (non-overweight vs. obesity: OR = 2.260, 95% CI [1.318, 3.874]; overweight vs. obesity: OR = 2.096, 95% CI [1.167, 3.766]), healthy HF (non-overweight vs. obesity: OR = 2.048, 95% CI [1.105, 3.796]) and healthy FF (overweight vs. obesity: OR = 2.084, 95% CI [1.099, 3.952]) reduced obesity risk. Overweight students with healthy FF were less likely to become obese regardless of PA (inactive: OR = 2.181, 95% CI [1.114, 4.272]; active: OR = 3.870, 95% CI [1.719, 8.713]) or HF (unhealthy: OR = 4.615, 95% CI [1.049, 20.306]; healthy: OR = 5.116, 95% CI [1.352, 19.362]). The MEs of inactive PA and unhealthy FF were −0.071, 0.035, and 0.036 for non-overweight, overweight, and obese individuals, respectively (p < 0.05); the MEs of HF and healthy FF individuals were −0.267 and 0.198 for non-overweight and obese individuals, respectively (p < 0.05). Conclusions: Unhealthy FF regulated the influence of inactive PA or unhealthy HF on adolescent obesity, altogether leading to a higher risk of obesity.

Adolescent Knowledge, Attitudes and Practices of Healthy Eating: Findings of Qualitative Interviews among Hong Kong Families

To tackle unhealthy eating among adolescents, it is crucial to understand the dietary knowledge, attitudes, and practices (KAP) on which adolescent eating habits are based. This qualitative study identifies the gaps in KAP by exploring what Chinese adolescents know, perceive, and practice regarding healthy eating to better inform targeted interventions for this important health problem. Parent–adolescent dyads were purposively sampled based on, for example, the dietary intake, age, and gender of the adolescent and household income, and each completed a 30 to 60 min interview. Twelve themes were synthesized: knowledge: (1) dietary recommendations, (2) health outcomes of healthy eating, (3) nutrition content in food, and (4) access to healthy meals; attitudes: (5) outcome expectation for healthy eating, (6) food preferences, and (7) self-efficacy regarding adopting healthy eating; and practices: (8) going grocery shopping for healthy food, (9) eating home-prepared meals. (10) eating out in restaurants or consuming takeaway food, (11) fruit and vegetable consumption, and (12) snacking, perceived unhealthy eating to be low risk, made unhealthy choices regarding snacking and eating out, and had insufficient fruit and vegetable intake. Programs should emphasize the positive short-term health outcomes of healthy eating and empower adolescents to acquire food preparation skills to sustain healthy eating habits.

Associations between sleep duration, sleep quality, and weight status in Chinese children and adolescents

Background and objective

The high prevalence of obesity is a serious problem, and sleep is considered to be a factor for obesity. This study aimed to examine the relationship between sleep duration, sleep quality, and weight status among children and adolescents in China and to explore whether the relationship between sleep duration and weight status is independent of sleep quality. Sex and age differences were also explored.

Methods

A cross-sectional research was conducted among 2019 children and adolescents (1029 boys and 990 girls) aged 8–16 years in Shanghai. An open-question was used to obtain data on sleep duration, which was categorized into the following four groups based on the age-specific National Sleep Foundation Sleep Duration Recommendations: 1) very short, 2) short, 3) recommended, and 4) long. The Pittsburgh Sleep Quality Index was used to assess sleep quality. Weight and height were measured for all participants. The variable weight status was estimated with the Chinese children and adolescent age- and sex-specific body mass index (BMI) and was categorized into overweight/obesity and normal weight.

Results

Short sleep duration (7–8 and 6–7 h for 6–13 and 14–16 years old, respectively) significantly increased odds of overweight/obesity (OR = 1.32, 95% CI: 1.06–1.64) compared with that of the recommended sleep duration (9–11 and 8–10 h for 6–13 and 14–16 years old, respectively). The relationship between the two variables existed independent of sleep quality. No significant relationship was found between sleep quality and overweight/obesity of children and adolescents. Sleep quality (OR = 1.07, 95% CI: 1.01–1.14) and short sleep duration (OR = 1.51, 95% CI: 1.06–2.13) increased the risk for overweight/obesity among girls, whereas no significant relationships between sleep duration, sleep quality, and overweight/obesity were found among boys. Short sleep duration increased the risk of overweight/obesity in children aged 8–13 years (OR = 1.34, 95% CI: 1.05–1.71), independent of sleep quality, but no significant relationships between these two variables existed for adolescents aged 14–16 years.

Conclusions

Overall, short sleep duration increased the risks of overweight/obesity in children and adolescents in China, independent of sleep quality. This relationship is significant for girls and children aged 8–13 years instead of boys and adolescents aged 14–16 years. Interventions to extend the sleep duration of children and adolescents, especially girls and children aged 8–13 years in China, are necessary to improve their weight status.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13534-w.

Trends in Obesity and Obesity-Related Risk Factors among Adolescents in Korea from 2009 to 2019

This study was conducted to identify the trends in obesity prevalence among adolescents and changes in the risk factors related to obesity. The study analyzed secondary data obtained from Korean Youth Risk Behavior Web-based Surveys conducted from 2009 to 2019. The Korean Youth Risk Behavior Web-based Survey is an annual survey of a nationwide representative sample of enrolled students aged 13–18 years in middle and high schools in Korea. Linear and trend analyses showed that the prevalence of obesity increased by 0.47% on average annually; this increase was statistically significant. Healthy food intake decreased significantly, but the prevalence of unhealthy food intake and the prevalence of skipping breakfast increased significantly. Vigorous-intensity physical activity, physical activity for over 60 min a day, and muscle-strengthening exercise for more than 3 days a week increased significantly, but so did the adolescents’ sedentary time. Therefore, health care providers and public policymakers need to actively manage adolescent obesity, which has been continuously increasing since 2009. In addition, long-term trends in obesity-related risk factors such as physical activity and dietary behaviors need to be considered in the development of obesity management strategies.

The Different Effects of Skeletal Muscle and Fat Mass on Height Increment in Children and Adolescents Aged 6-11 Years: A Cohort Study From China

OBJECTIVE

This study aimed to investigate the contribution of body composition including skeletal muscle mass (SMM) and body fat mass (BFM) to longitudinal growth among children and adolescents aged 6-11 years old.

METHODS

This cohort study was conducted from the annual health examination between 2019 and 2020. Annual height gain and weight gain and changes in SMM and BFM were calculated and compared between sexes, different nutritional status, and growth curve shifting mode. Spearman analyses and multiple linear regression analysis were performed to identify the impact of SMM, BFM, or body mass index (BMI) on height gain.

RESULTS

Of the 584 subjects, the annual height gains of boys (4.76 cm in the 6-9-year group and 4.63 cm in the 10-11-year group) were significantly lower than those of girls (5.48 and 5.74 cm, respectively). Spearman analysis showed that SMM gain and height gain were positively and significantly correlated in each examination of all children (r = 0.535 for boys and 0.734 for girls, p < 0.001). Conversely, BFM and height gains were negatively (r = -0.5240 for boys and -0.232 for girls, p < 0.001) correlated. Multiple linear regression analysis identified SMM gain as an independent predictor (95% CI: 1.20,1.44) of height gain after adjusting for age, gender, BMI, BFM gain, and percentage of body fat (PBF).

CONCLUSION

SMM gains, rather than BFM gains, were associated with height gains in children and adolescents aged 6-11 years. Monitoring SMM changes in routine healthcare might motivate children and adolescents to achieve dietary and exercise recommendations, thereby growing taller without gaining excessive weight.

Overweight/Obesity in Childhood and the Risk of Early Puberty: A Systematic Review and Meta-Analysis

PURPOSE

To determine the relationship between childhood overweight/obesity and early puberty in both boys and girls. Specifically, this is the first time to conduct a meta-analysis of the relationship between childhood overweight/obesity and early puberty in boys.

METHODS

Relevant studies were identified from PubMed, Web of Science, and EMBASE searches. The exposure of interest was overweight/obesity in childhood. Childhood was defined internationally as the age range of 0-18 years. The overall risk estimates were pooled using random effects models. Subgroup and sensitivity analyses were performed to explore possible sources of heterogeneity and to assess the robustness of the results.

RESULTS

A total of 10 studies involving 13,338 girls and 12,796 boys were included. Results showed that childhood overweight/obesity were associated with a significantly higher risk of early puberty in girls [odds ratio (OR): 2.22, 95% CI: 1.65-2.99]. Although without statistical significance, a higher risk of early puberty was also found in boys who were overweight/obese in childhood (OR: 1.29, 95% CI: 0.98-1.70). Heterogeneity in the risk estimates of early puberty was partially explained by study design, sample size, follow-up duration, definitions of early puberty and confounders controlled. Sensitivity analyses validated the robustness of the findings.

CONCLUSIONS

Our findings showed that for girls the associate between overweight/obesity and early puberty is definite or strong whereas for males, such an association is possible, prompting that future studies need to further explore the possible relationship between overweight/obesity and early puberty in boys.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021264649, PROSPERO CRD42021264649.

How Does the Family Influence Adolescent Eating Habits in Terms of Knowledge, Attitudes and Practices? A Global Systematic Review of Qualitative Studies

Promoting healthy eating habits can prevent adolescent obesity in which family may play a significant role. This review synthesized findings from qualitative studies to identify family barriers and facilitators of adolescent healthy eating in terms of knowledge, attitudes, and practices (KAP). A literature search of four databases was completed on 31 July 2020; qualitative studies that explored family factors of adolescent (aged 10 to 19 years) eating habits were included. A total of 48 studies were identified, with the majority being from North America and sampled from a single source. Ten themes on how family influences adolescent dietary KAP were found: Knowledge—(1) parental education, (2) parenting style, and (3) family illness experience; Attitudes—(4) family health, (5) cultivation of preference, and (6) family motivation; Practices—(7) home meals and food availability, (8) time and cost, (9) parenting style, and (10) parental practical knowledge and attitudes. This review highlights five parental characteristics underlying food parenting practices which affect adolescents’ KAP on healthy eating. Adolescents with working parents and who are living in low-income families are more vulnerable to unhealthy eating. There is a need to explore cultural-specific family influences on adolescents’ KAP, especially regarding attitudes and food choices in Asian families.

Parental Adherence to Ideal Cardiovascular Health Status Was Associated With a Substantially Lower Prevalence of Overweight and Obesity in Their Offspring Aged 6-18 Years

Background: Parental health status had a potential influence on offspring health. This study aimed to investigate the separate associations between paternal and maternal cardiovascular health statuses and the prevalence of childhood overweight and obesity in the offspring. Methods: Data were from a cross-sectional study conducted in seven provinces or cities of China in 2013. A total of 29,317 children aged 6-18 years old and their parents, making up 9,585 father-offspring pairs and 19,732 mother-offspring pairs, were included in the final analysis. Information on parental cardiovascular health status factors (dietary behaviors, body mass index (BMI), smoking, physical activity, hypertension, and diabetes mellitus) was obtained from the structured self-administrated questionnaires. Based on the health status factors, we then generated an ideal cardiovascular health (iCVH) score. The overweight and obesity of children were defined using age- and sex-specific cutoffs based on the International Obesity Task Force criteria. A multilevel log-binomial regression model was used to assess the association between parental cardiovascular health status and prevalence of childhood overweight and obesity in the offspring. Results: The prevalence of pediatric overweight and obesity was 22.0% in the father-offspring subset and 23.8% in the mother-offspring subset, respectively. Fathers with ideal BMI, non-smoking, and absence of hypertension and diabetes, and mothers with ideal BMI, ideal physical activity, and absence of hypertension and diabetes were found to be associated with lower prevalence of overweight and obesity in the offspring. The prevalence of offspring overweight and obesity was significantly decreased with the parental iCVH scores increased. Each additional increase in paternal and maternal iCVH factor was associated with a 30% and 27% lower prevalence of overweight and obesity in the offspring. Compared with children whose parental iCVH scores ≤ 3, offspring whose fathers or mothers met all six iCVH factors had 67% [prevalence ratio (PR): 0.33, 95%CI: 0.25-0.42] and 58% (PR: 0.42, 95%CI: 0.29-0.62) lower prevalence of overweight and obesity, respectively. Conclusions: Parental adherence to iCVH status was associated with a lower prevalence of pediatric overweight and obesity in offspring. Our findings support the intervention strategy that parents should involve in the obesity intervention program for children.

The association between frequency of eating out with overweight and obesity among children aged 6-17 in China: a National Cross-sectional Study

BACKGROUND

In parallel with the increased prevalence of childhood overweight and obesity, the proportion of eating out in China has increased dramatically in recent years. The purpose of the study was to explore the association between frequency of eating out with overweight and obesity among Chinese children.

METHODS

The representative sample was recruited from Chinese National Nutrition and Health Survey (CNNHS) in 2010-2012, which included Chinese children aged 6-17 years (7685 boys and 7576 girls). Frequency of eating out was collected by interview-administered questionnaire and categorized as: 0, 1-2 and ≥ 3 times per week. Height and weight were measured, consequently body mass index was calculated.

RESULTS

The prevalence of eating out among Chinese children aged 6-17 years old was 23.2%. Children who ate out 0, 1-2, ≥3 times per week were accounted for 76.8, 10.9 and 12.3% respectively. Findings revealed that eating out three times per week or more was statistically significant associated with higher prevalence of overweight and obesity among boys (OR = 1.20,95CI:1.04-1.38) compared with those ate out less than three times per week. However, no significantly association was observed among girls (OR = 0.91, 95CI:0.78-1.01). In additional, Younger children, rural children, children from low income family, those with leisure exercises (certain physical activities regularly carried out such as swimming, walking, running, equipment fitness), leisure time sedentary behaviors (LTSB)(> 2 h/d) were relatively more likely to eat out.

CONCLUSIONS

The results illustrated that eating out three times or more had a significantly positive effect on overweight and obesity among boys in China.

Annual incidence and prevalence of obesity in childhood and young adulthood based on a 30-year longitudinal population-based cohort study in Korea: the Kangwha study

PURPOSE

Childhood obesity is a major global issue that causes a variety of health problems and high social costs. Many previous studies have investigated childhood obesity using cross-sectional data, but few longitudinal cohort studies have been performed, especially in the Korean population.

METHODS

We analyzed the incidence and prevalence of obesity and overweight in a Korean prospective cohort study of children that were followed-up from age 7 to age 36. The study eventually recruited a total of 1216 participants, with 16 follow-up surveys over 30 years (1986-2017).

RESULTS

The annual incidence of obesity showed a small peak (2.1%) at age 13 when the cohort entered middle school, but a rapid increase (6.4%) when participants reached the age of 20. The prevalence of obesity and overweight at age 8 was 0.8% and 0.9%, respectively, and increased rapidly from age 12 (obesity 2.2%, overweight 4.6%), reaching 9.5% and 15.9%, respectively, at age 20. The prevalence of obesity and overweight was consistently higher in girls than in boys during the childhood period, but this trend reversed in adulthood.

CONCLUSIONS

Incidence and prevalence of obesity and overweight increased markedly after the final grades of elementary school in females, but after adolescence in males.

Growth and Weight Status in Chinese Children and Their Association with Family Environments

The growth status and weight status of Chinese children have experienced remarkable changes in the past decades. Using China Health and Nutrition Survey (CHNS) data, this paper examines the secular trends and disparity of the growth status and weight status in Chinese children and further investigates the impact of various family environments on children’s growth from 1991 to 2011. We found an increasing trend in standardized growth indicators (height, weight, and BMI), overweight, and obesity from 1991 to 2011. We also observed an increasing disparity in overweight and obesity over time. Family environments had a significant impact on children’s growth status and weight status. In particular, children that live in families with a small size, higher family income, better sanitary conditions, and with well-educated parents or overweight parents tended to be taller and heavier and have a higher BMI, lower risk of being underweight, and higher risk of exhibiting overweight and obesity. Further decomposition analysis showed that more than 70% of the disparity in standardized height, weight, and overweight and around 50% of the disparity in standardized BMI, underweight, and obesity could be attributed to heterogeneity in family environments. Moreover, the disparity associated with family environments tended to increase over time.

Meeting 24-h movement guidelines: Prevalence, correlates, and the relationships with overweight and obesity among Chinese children and adolescents

BACKGROUND

Meeting 24-h movement guidelines by children and adolescents has been associated with improved indicators of health, although it has been under-studied in China. Hence, this study aimed to investigate the prevalence of meeting the 24-h movement guidelines, its correlates, and its relationships with body mass index in children and adolescents in China.

METHODS

Cross-sectional data from the 2017 Youth Study in China of 114,072 children and adolescents (mean age = 13.75 years, 49.18% boys) were used. Meeting 24-h movement guidelines (≥60 min of daily moderate-to-vigorous physical activity, ≤2 h of daily leisure screen time, 9-11 h and 8-10 h nightly sleep duration for 6-13-year-olds and 14-17-year-olds, respectively) and height and weight of all participants were assessed. The prevalence of meeting the 24-h movement guidelines and World Health Organization weight status categories were determined. Generalized linear models were used to determine the correlates of meeting the 24-h movement guidelines and the relationships of meeting the 24-h movement guidelines with overweight (OW) and obesity (OB).

RESULTS

Only 5.12% of Chinese children and adolescents met the 24-h movement guidelines, and 22.44% were classified as OW/OB. Older children and adolescents were less likely to meet the 24-h movement guidelines. Parental education level and family income were positively related to meeting the 24-h movement guidelines. Children and adolescents meeting the 24-h movement guidelines showed lower odds ratios for OW/OB. Compared with participants meeting the 24-h movement guidelines, boys in 4th-6th grades met none of the recommendations (OR = 1.22, 95%CI: 1.06-1.40), met the screen time recommendation only (OR = 1.13, 95%CI: 1.01-1.28), met the nightly sleep duration recommendation only (OR = 1.14, 95%CI: 1.03-1.28), and had significantly higher odds ratios for OW/OB. Similar trends were observed for girls in 4th-6th grades: meeting none of the guidelines (OR = 1.35, 95%CI: 1.14-1.59), meeting sleep duration guidelines only (OR = 1.23, 95%CI: 1.08-1.39), and meeting moderate-to-vigorous physical activity + nightly sleep duration guidelines (OR = 1.24, 95%CI: 1.01-1.54). For girls in 7th-9th grades, the following trend was observed: meeting none of the guidelines (OR = 1.30, 95%CI: 1.01-1.67).

CONCLUSION

Very few Chinese children and adolescents met the 24-h movement guidelines. Age (negatively correlated), parental education level, and family income (both positively correlated) were correlates of meeting the 24-h movement guidelines. Children and adolescents meeting the 24-h movement guidelines were more likely to have lower risks for OW/OB, especially in the youngest age group (Grades 4-6); and girls in the middle age group (Grades 7-9) were also more likely to have lower risks for OW/OB. Further research studies should explore additional correlates and determinants for meeting the 24-h movement guidelines. Also, future studies should use longitudinal or interventional designs to determine the relationships between meeting the 24-h movement guidelines and OW/OB and other health indicators, while taking sex and age differences into account.

Barriers and facilitators to physical activity among ethnic Chinese children: a qualitative systematic review

OBJECTIVE

The review aimed to synthesize the barriers and facilitators from the available studies that explored physical activity among ethnic Chinese children and uncover any differences or similarities in these barriers and facilitators.

INTRODUCTION

Physical activity promotes overall health, fitness, and well-being in children, yet prevalence of this has been low among ethnic Chinese children who reside in either Chinese and non-Chinese territories. Research has been conducted to explore the barriers and facilitators to physical activity among ethnic Chinese children. However, no qualitative systematic review has been conducted to synthesize these barriers and facilitators.

INCLUSION CRITERIA

Studies were considered for inclusion if they explored the barriers and facilitators to physical activity among ethnic Chinese children aged six to 17 years in either Chinese or non-Chinese territories, or among people who had responsibility for them in school, home, and community settings. The review included studies that focused on their views, experiences, attitudes, understandings, perceptions, and perspectives. Studies were included if they focused on qualitative data including, but not limited to, designs such as phenomenology, ethnography, grounded theory and action research. In addition, the authors considered cross-sectional surveys to find any free text relating to the review question.

METHODS

MEDLINE, Embase, CINAHL, PsycINFO, BNI, AMED, Web of Science, Scopus, CNKI, Wanfang and VIP databases were searched to identify published studies. The search for unpublished studies included EThOS, OpenGrey, ProQuest Dissertations and Theses, CNKI and Wanfang. Databases were searched from their inception dates to 10 December 2018 and no language restrictions were applied. The JBI guidelines for qualitative systematic reviews were followed in conducting the review. The JBI process of meta-aggregation was used to identify categories and synthesize findings.

RESULTS

Out of 9460 records identified, 11 qualitative studies met the eligibility criteria and were included in the review. Using the JBI checklist for qualitative research (10 criteria), the critical appraisal scores of the majority of studies ranged from a moderate score of 6 (n = 1) to a high score of 7 and above (n = 9). Seven studies were from China, two from Australia, one each from the United Kingdom and the United States. The sample size ranged from 12 to 115 participants. A total of 56 findings were extracted and aggregated into 21 categories, based on the similarity of meaning. From studies conducted in the Chinese territories, four synthesized findings (personal, socio-cultural, environmental, and policy- and program-related barriers and facilitators) were aggregated from 37 extracted findings and 14 aggregated categories. From studies conducted in the non-Chinese territories, only two synthesized findings (personal and socio-cultural barriers and facilitators) were derived from 19 extracted findings and seven aggregated categories. Based on the ConQual scores, confidence in the synthesized findings was moderate.

CONCLUSIONS

Four broad themes emerged from the participants' accounts, namely personal, socio-cultural, environmental, and policy- and program-related factors. Barriers and facilitators at the personal and socio-cultural level (e.g., parents and teachers) were most frequently cited, reflecting the importance of children's self-influence and the role of adults. Future interventions are needed to address the identified barriers and enhance the facilitators.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42018097124.

Eating-out behaviors, associated factors and associations with obesity in Chinese school children: findings from the childhood obesity study in China mega-cities

PURPOSE

Eating-out and prevalence of obesity/overweight have been rising rapidly in China in the past two decades due to social economic developments. This study examined Chinese school children's eating-out behaviors and associated factors, including their association with obesity during a 3-year follow.

METHODS

Data were collected from 3313 primary and middle school children aged 7-16 years in five mega-cites across China in 2015, 2016 and 2017, in an open cohort study. Eating-out behaviors were assessed using questionnaire survey. The Chinese age-sex-specific body mass index (BMI) cutoffs were used defining child overweight/obesity (combined) and obesity; central obesity was defined as WHtR ≥ 0.48. Mixed effect models examined associations between child eating-out behaviors and BMI, overweight and obesity in this longitudinal data, adjusting for other covariates.

RESULTS

About 80.1% of the children reported having eaten out ≥ 1 times/week over the past 3 months; 46.7% and 70.9% chose Western- and Chinese-style food when ate out, respectively. Meanwhile, 29.8% of them were overweight/obese, 12.7% were obese and 20.1% had central obesity. Child eating-out behaviors were positively associated with parents' eating-out behaviors (p < 0.05). Boys were more likely to choose Western-style food than girls (OR 1.27; 95% CI 1.09-1.48) when eating out. Compared to non-overweight/obese children, those being overweight/obese at baseline were less likely to eat out dining on Western-style food during the follow-up.

CONCLUSION

Eating-out is common among school children in major cities in China, but with considerable differences across groups. Children's weight status was associated with eating-out behaviors.

Breakfast preferences and consumption location among children at a median age of 7 in Shenzhen: Implications for managing overweight and obesity

BACKGROUND

Breakfast is commonly described as the most important meal of the day; however, we have little information regarding its relevance for childhood overweight and obesity in southern mainland China. This study aimed to assess the association between breakfast preferences, consumption location and overweight and obesity for children in Shenzhen.

METHODS

Among 6126 children (median age 7.2 years) at primary schools, 3504 were finally included after a questionnaire survey and physical examination. Ten commonly consumed foods/beverages for breakfast in southern China were exposure variables, and consumption location, total energy demographic and other dietary characteristics were covariates in logistic regression to determine the effect of breakfast preferences on overweight and obesity, estimating odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Probability of overweight/general obesity was inversely associated with children eating plain congee for breakfast (adjusted OR 0.689, 95% CI 0.566-0.838), restricted to boys after stratification. Probability of overweight/general obesity and central obesity was positively associated with usually eating steamed rice roll for breakfast (OR 1.309, 95% CI 1.090-1.571 and OR 1.351, 95% CI 1.064-1.717, respectively), but the effect on overweight/obesity remained statistically significant for only boys after stratification. Eating steamed rice roll for breakfast and eating out for breakfast had an additive interaction on overweight/obesity. Additionally, eating bread for breakfast had a mild favorable effect on overweight/obesity but only for girls.

CONCLUSIONS

Keeping a healthy weight might benefit children who eat plain congee or bread for breakfast in China. However, frequent consumption of steamed rice roll for breakfast and especially eating out could contribute to overweight and obesity. Thus, we need to promote a healthier breakfast pattern among children in southern China to reduce the odds of obesity.

High Prevalence of Obesity but Low Physical Activity in Children Aged 9-11 Years in Beijing

OBJECTIVE

To investigate the prevalence and associated factors of childhood overweight/obesity in the Shunyi district of Beijing, China.

METHODS

This study adopted a cross-sectional survey and included 10,855 children aged 6-18 years in the Shunyi district of Beijing, China. Analyses were stratified by age group (6-8, 9-11, 12-14, and 15-18 years).

RESULTS

The prevalence of overweight and obesity among children aged 6-18 years was high with 17.62% and 29.05% in boys, 17.57% and 18.04% in girls, respectively. Both boys and girls aged 9-11 years had the highest rate of obesity in comparison with the other age groups, though the differences in children aged 9-11 years and 12-14 years were not statistically significant. Compared with age 6-8 years, age 9-11 years (OR=1.59, 95% CI 1.41-1.79, P<0.01) and 12-14 years (OR=1.26, 95% CI 1.48-1.73, P<0.01) were independently positively associated with obesity. Importantly, in all subjects, the percentages of being physically active (exercise time ≥120 minutes/week) were lower in children aged 9-11 years in comparison to children in other age groups. This phenomenon remained when this comparison was performed respectively in the normal-weight, overweight, and obesity groups. Even after adjustment for other potential confounders, the probability of being physically active (exercise time ≥120 minutes/week) was lower in children aged 9-11 years (OR=0.86, 95% CI 0.78-0.94, P<0.01), but higher in children aged 12-14 years (OR=1.91, 95% CI 1.69-2.17, P<0.01) and aged 15-18 years (OR=2.22, 95% CI 1.85-2.66, P<0.01), when compared with children aged 6-8 years.

CONCLUSION

Children aged 9-11 years had a higher prevalence of obesity, but a lower percentage of being physically active. Targeted intervention programs in this key group are needed to address this problem in China.

Body Mass Index and Its Change from Adolescence to Adulthood Are Closely Related to the Risk of Adult Metabolic Syndrome in China

AIMS

To investigate the influence of body mass index (BMI) and its change from adolescence to adulthood (ΔBMI) on the risk of metabolic syndrome (MetS) in early adulthood.

METHODS

We selected 931 students from 12 to 16 years of age in Liaoyang City, China. Ninety-three participants from 18 to 22 years of age with complete baseline data were available for follow-up after 5 years. Statistical analysis determined the relationship of MetS at follow-up with baseline BMI (BMI_b), ΔBMI, and follow-up BMI (BMI_f).

RESULTS

ΔBMI was positively correlated with the change of waist circumference (ΔWC), systolic blood pressure (ΔSBP), triglycerides (ΔTG), uric acid, and glycosylated hemoglobin (ΔHbA1c) in follow-up (p < 0.05). For every 1 kg/m² increase in BMI_b, ΔBMI, and BMI_f, the risk of MetS at follow-up increased 1.201-fold, 1.406-fold, and 1.579-fold, respectively. Both BMI_b and ΔBMI were predictive of MetS at follow-up, with prediction thresholds of 23.47 kg/m² and 1.95 kg/m². The participants were divided by the predicted BMI_b and ΔBMI threshold values into four study groups. Interestingly, the group with lower BMI but a higher increase in BMI presented the same metabolic derangements and Mets% of the group with higher BMI but lower Δ BMI.

CONCLUSION

Both BMI of adolescence and ΔBMI were predictive of MetS and cardiovascular risk factors in adulthood. Control of both variables in adolescents would be more effective in decreasing the risk of MetS in young adults than control of BMI alone.

The Relationship between Body Mass Index and Physical Fitness among Chinese University Students: Results of a Longitudinal Study

Over the past few decades, a gradual increase in sedentary lifestyles along with the increased consumption of a modern, hypercaloric diet has resulted in a substantial increase in the number of those classified as overweight or obese in China. The prevalence of overweight and obesity has become a key public health issue. However, it is important to be cautious when interpreting the literature as the majority of studies apply cross-sectional data to assess and subjectively compare the relationship between physical fitness and being overweight and obese. In the present study, longitudinal data were collected from 3066 students (enrolled in 2014) at a university in China at the beginning of each academic year throughout their four-year university program. The aim of this study was to analyze the various associations between BMI, explosive power, flexibility, and cardiorespiratory endurance, and a random-intercept panel model (RIPM) was separately employed on male and female participants to identify between- and within-person variations. In this way, the associations for between-person physical fitness and normal/overweight/obese weight ranges, and for within-person physical fitness and normal/overweight/obese weight ranges could be observed. The results of this study revealed that every physical fitness test chosen for evaluation (such as the standing long jump for explosive power or the distance run for cardiorespiratory endurance) was negatively related to the BMI results, irrespective of sex, with the notable exception of the flexibility results. In addition, this study showed that both males and females exhibited positively correlated results in both between-person BMI and flexibility as well as within-person BMI and flexibility. Furthermore, the relationships between and within persons of cardiorespiratory endurance, explosive power, and flexibility all showed positive correlations across both sexes. The dynamics between physical fitness and BMI identified in this study could prove useful to practitioners and researchers investigating such relationships in the future.

Associations of outdoor activity and screen time with adiposity: findings from rural Chinese adolescents with relatively low adiposity risks

Background

Whether and to what extent outdoor activity and screen time are relevant to adiposity among rural adolescents remain largely unknown as most of relevant evidence was generated from high-income countries and urban areas. This study aimed to investigate associations of outdoor activity and screen time with adiposity among early adolescents living in rural southwest China.

Methods

In this cross-sectional study, seventh graders (n = 2264) were recruited from 10 middle schools of a rural county. Overweight and obesity was assessed using adolescents’ body mass index and waist circumference. Adolescents’ outdoor activity and screen time were measured using self-reported daily time spending on outdoor activity, watching TV, playing video games, and computers on weekdays and weekends, respectively.

Results

The prevalence of overweight/obesity and high waist circumferences were 8.0 and 4.9% and were higher among those from one-child families and with parents having high school or higher education and whose fathers were not farmers. Adolescents who did not have ≥1 h outdoor activity on weekdays were more likely to be overweight/obese (OR: 1.86, 95% CI: 1.30, 2.66) and have high waist circumferences (OR: 2.22, 95%CI: 1.39, 3.57). Adolescents who had > 2 h screen time on weekends were more likely to have high waist circumferences (OR: 2.08, 95% CI: 1.14, 3.80). Lack of outdoor activity and excessive screen time also showed synergistic effects on overweight/obesity (OR: 1.93. 95% CI: 1.15, 3.24) and high waist circumferences (OR: 3.02, 95% CI: 1.54, 5.94).

Conclusions

Lack of outdoor activity and excessive screen time were relevant to adiposity among rural Chinese adolescents even when the obesity prevalence was low. Efforts to promote active lifestyles may help prevent rural adolescents from losing their advantage in the era of the global obesity epidemic.

Association between birth weight and risk of abdominal obesity in children and adolescents: a school-based epidemiology survey in China

BACKGROUND

Abdominal obesity is becoming an increasingly serious public health challenge in children and adolescents, there remains controversial opinions on birth weight and risk of childhood abdominal obesity. This study aims to assess the association between birth weight and the risk of abdominal obesity in childhood, as well as to compare the associations among different sex and age groups.

METHODS

A total number of 30,486 (15,869 boys and 14,617 girls) participants aged 6-17 years old were included in this study. Participants were classified into five groups according to their birth weight. Waist-to-height ratio (WHtR) was used to define abdominal obesity. Fractional polynomial regression model was used to assess the association between birth weight and WHtR, and a multi-variable logistic regression model was applied to evaluate the risk of abdominal obesity in different birth weight groups.

RESULTS

A J-shaped association was observed between birth weight and WHtR. Compared with birth weight of 2500-2999 g, high birth weight was associated with increased risk of abdominal obesity [OR (95% CI) for 3000-3499 g: 1.12(1.00-1.24); 3500-3999 g: 1.19(1.07-1.34); ≥4000 g: 1.42(1.24-1.62)]. No significant correlation was observed in children with birth weight ≤ 2499 g. Similar patterns were observed across different age groups. Abdominal obesity risk for high birth weight was particularly pronounced in boys compared to girls.

CONCLUSIONS

Birth weight ≥ 3000 g, especially for boys, was associated with an elevated risk of abdominal obesity in childhood and may benefit from intervention to mitigate this risk.

Overweight and obesity among Vietnamese school-aged children: National prevalence estimates based on the World Health Organization and International Obesity Task Force definition

Background

Overweight and obesity is a severe global health issue in both developed and developing nations. This study aims to estimate the national prevalence of overweight and obesity among school-aged children in Vietnam.

Method

We conducted a national cross-sectional study on 2788 children aged from 11–14 years old from September to November 2018. We applied the WHO 2007 and IOTF criteria to estimate the prevalence of overweight and obesity among participants. Poison regression analysis with cluster sampling adjustment was employed to assess associated factors with obesity and overweight. Metadata on sociodemographic characteristics, physical measurements, and lifestyle behaviors were also extracted to investigate these factors in association with overweight and obesity prevalence.

Results

The prevalences of overweight and obesity in Vietnamese children were 17.4% and 8.6%, respectively by WHO Z-score criteria, and 17.1% and 5.4%, according to the IOTF reference. Using WHO Z-score yielded a higher prevalence of obesity than the IOTF and CDC criteria of all ages and both sexes. The proportions of overweight and obesity were substantially higher among boys than girls across ages. Parental BMI was shown to be a significant factor associated with overweight/obesity status in both girls and boys. Only for boys, age (PR = 0.83, 95% CI 0.76–0.90) and belonging to ethnic minorities (PR = 0.43, 95% CI 0.24–0.76) were significant risk factors for overweight/obesity.

Conclusion

Our findings indicate a high prevalence of childhood overweight and obesity in Vietnam, especially in boys.

Pubertal maturation and weight status are associated with dyslipidemia among children and adolescents in Northwest China

Dyslipidemia is one of major risk factors for cardiovascular disease. The early detection and treatment of dyslipidemia can reduce cardiovascular disease risk. A cross-sectional study was carried out in Ningxia, China to determine the prevalence of dyslipidemia and its association with body mass index (BMI) and pubertal stage. A total of 1783 students were selected from middle schools and high schools in September 2014 using stratified random cluster sampling. Serum triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were measured by using MOL-300 automatic biochemical analyzer with associated kits. The prevalence of adolescents with one abnormal serum lipid component was 43.2% and was significantly different across three pubertal stages (p < 0.0001). The abnormal rates of HDL-C and TG increased as the students maturated through the early, middle, and late stages of puberty (all p < 0.0001). Similar results were obtained when separate analyses were performed for boys and girls. In linear regression analysis, BMI was positively associated with serum levels of TC, LDL-C, and TG, but inversely associated with serum levels of HDL-C after the adjustment for age, sex, and race. In multivariable logistic regression analysis, obesity was associated with an increased risk of developing high TC, while pubertal maturation was associated with an elevated risk of experiencing low HDL-C and high TG (all p < 0.05). In conclusions, dyslipidemia is common in an adolescent population of Northwest China and its prevalence rates substantially vary with weight status and pubertal stage.

The Effect of Boarding on Obesity Among Middle School Students: Evidence From China

PURPOSE

This paper examines the effect of boarding on obesity among middle school students at boarding schools.

DESIGN

Quantitative, cross-sectional study.

SETTING

Data from the China Education Panel Survey (CEPS) were analyzed. The CEPS samples middle school students from 7th grade to 9th grade in China.

SUBJECTS

The final sample included 3,892 observations of boarding school students.

MEASURES

Measures included body mass index (BMI) that determined obesity, boarding status, demographic information, and instruments for boarding status.

ANALYSIS

The instrumental variables approach based on the 2 stage least squares (2SLS) methodology was utilized. The endogenous models and the extended probit models were also applied to the data to confirm the robustness of the results.

RESULTS

Boarding has a significant negative effect on obesity for middle school boys but a smaller negative effect on obesity for middle school girls. Boarding was estimated to reduce obesity by roughly 14% (p < 0.01) among middle school boys and 6% (p > 0.1) among middle school girls. The overall estimated effect based on the pooled sample was about 10% (p < 0.01).

CONCLUSION

School or government policies that encourage boarding at school can reduce obesity among middle school students, at least for middle school boys. Boarding at school can be a positive factor in preventing and controlling obesity among middle school students.

Differences in Neuregulin 4 Expression in Children: Effects of Fat Depots and Obese Status

PURPOSE

To observe the expression of Nrg4, uncoupling protein-1 (UCP1), tumor necrosis factor α (TNFα), CD31, VE-cadherin/CDH5 and vascular endothelial growth factor A (VEGF-A) mRNA in abdominal subcutaneous (SC), omental (OM) adipose tissue in children with relation to anthropometric parameters. Further to verify the effect of inflammatory mediators on Nrg4 and UCP1 mRNA expression in adipocytes.

METHODS

Paired SC and OM adipose tissues were obtained from 58 children. In vitro, the adipocytes isolated from primary inguinal adipose tissue of mice were treated with TNFα (50 ng/ml) for 12-48 h. mRNA levels of Nrg4, UCP1 and TNFα were determined by real-time PCR.

RESULTS

Nrg4, UCP1, VEGF-A and CDH5 mRNA levels in SC were significantly higher than those in OM adipose tissue and the mRNA level of TNFα showed the opposite result. Moreover, Nrg4 and UCP1 mRNA in SC were significantly lower in overweight children compared to normal weight children. Nrg4 in SC and OM was negatively associated with BMISDS, WHtR. CDH55 mRNA in OM was negatively associated with WHR. VEGF-A was positively correlated with Nrg4 in SC. In vitro, Nrg4 and UCP1 mRNA levels in adipocytes were dose- and time-dependently decreased under TNFα treatment.

CONCLUSIONS

Nrg4, UCP1, VEGF-A and CDH5 mRNA expression in adipose tissues display a depot-specific pattern. Nrg4 mRNA levels in adipose tissue are decreased with obesity and associated with WAT browning and angiogenesis. TNFα may be involved in the regulation of Nrg4 level in adipose tissue, which may be one of the causes of the down-regulation of Nrg4 expression in obesity with chronic inflammatory response.

Prevalence and correlates of overweight and obesity among adolescents in northeastern China: a cross-sectional study

OBJECTIVES

To estimate the prevalence of overweight/obesity among adolescents and evaluate the associated factors in this group in Changchun City in northeastern China.

METHODS

A cross-sectional study of 1955 adolescents aged 11-18 years was conducted in Changchun City using stratified cluster sampling. Parents and caregivers of children completed the questionnaires as requested without objection. The questionnaire included demographic characteristics and anthropometric parameters. Univariate and multivariate logistic regression analyses were performed to analyse the relationship between overweight/obesity and related factors.

RESULTS

In total, the prevalence of overweight was 12.7% (male 17.4%; female 10.1%) and of obesity was 4.9% (male 8.8%; female 3.1%) in Changchun, Jilin Province. The prevalence of overweight and obesity was higher in boys than in girls (p<0.001). Multivariate logistic regression showed that overweight and obesity were significantly associated with male sex (OR=1.91, 95% CI 1.48 to 2.47), eating fresh fruits more than 2 days per week (OR=1.41, 95% CI 1.09 to 1.84) and eating quickly (OR=1.37, 95% CI 1.06 to 1.78). Students who were not picky (OR=0.69, 95% CI 0.53 to 0.90) were less likely to be overweight, and adolescents whose father was overweight or obese (OR=0.67, 95% CI 0.52 to 0.86) or whose mother was overweight or obese (OR=0.72, 95% CI 0.52 to 0.99) were less likely to be overweight.

CONCLUSION

The prevalence of overweight and obesity among adolescents in Changchun has been high in recent years, and the prevalence was higher among boys than among girls. Sex, dietary habits (weekly frequency of fruit consumption, picky eating and slowness in eating) and parental weight were important factors for overweight and obesity in adolescents. Further research should be conducted on the health of adolescents in China, and further intervention measures should be implemented to reduce the prevalence of overweight/obesity.

Association between milk intake and childhood growth: results from a nationwide cross-sectional survey

PURPOSE

The literature is inconsistent regarding milk intake and physical growth. This study aims to evaluate the association of milk intake with body height and weight in a nationally representative sample of Chinese children.

METHODS

A total of 41,439 children ages 6-17 were recruited from 30 provinces in mainland China in 2013-2016 using a multistage stratified cluster sampling approach. Milk intake information was collected using a questionnaire aided with standard containers. Weight and height were measured using a standard physician beam scale with a height rod. Milk intake was categorized into no-, low-, and high-intake groups based on the intake rate, and weight status into normal, overweight, and obese groups based on the body-mass-index (BMI). Associations between height/weight status and milk intake were evaluated using multivariate weighted linear and logistic regression models.

RESULTS

Chinese children had low milk intake: 1/5 of children did not drink milk, and those drinking milk had a median intake of 100 ml/month. The low- and high-intake groups were 0.83 cm (95% confidence interval: 0.00, 1.68 cm) and 1.26 cm (0.34, 2.19 cm) taller than the no-intake group for girls, respectively, after adjusting for confounding factors. Boys with high milk intake had lower BMI (-0.56, 95% CI: -1.00, -0.12 kg/m²) and risk of obesity (OR = 0.67, 95% CI: 0.46, 0.97) than those without milk intake.

CONCLUSIONS

This study revealed the association of increased milk intake with increased body height and lowered obesity risk among Chinese children. Given the cross-sectional nature of the study and the possibility of residual confounding, further research is warranted to uncover the role of milk intake in promoting children's growth.

Prevalence of Overweight and Obesity among People Aged 18 Years and Over between 2013 and 2018 in Hunan, China

Background: Recent overweight and obesity prevalence data are lacking for China. Methods: Data were from provincially representative surveys conducted in 2013 and 2018 in Hunan Province, China. Overweight and obesity were defined according to the Chinese standard. Complex sampling weights were considered in statistical analyses. 95% confidence interval (95% CI) of rate was calculated. Results: The overall prevalence rate between 2013 and 2018 significantly increased from 20.81% (95% CI: 17.68–23.95) to 26.97% (95% CI: 23.48–30.45) for overweight and from 4.09% (95% CI: 3.21–4.96) to 7.13% (95% CI: 5.10–9.15) for obesity in Hunan Province of China, respectively. Urban residents and males had higher crude prevalence rates of overweight and obesity than rural residents and females in 2013 and in 2018. Notably, the peak age groups of overweight and obesity both became younger between 2013 and 2018. After controlling for Engel coefficient, level of education and frequency of physical exercise per week, the overweight prevalence significantly increased in urban males aged 65+ (adjusted OR: 1.52) and rural males aged 45–54 years (adjusted OR: 1.52) and 65+ (adjusted OR: 1.88) and the obesity prevalence rate rose significantly in many groups (urban males: 18–24 years, 25–34 years, 35–44 years and 55–64 years; urban females: 25–34 years, 35–44 years, 45–54 years; rural males: 18–24 years, 25–34 years; rural females: 35–44 years, 55–64 years), with adjusted OR varying from 1.56 to 5.52. Conclusion: The adult prevalence rates of overweight and obesity significantly increased between 2013 and 2018 in Hunan Province, China. The increasing prevalence rates and varying prevalence changes across groups warrantee further research and policy interventions.

Are only children in China more likely to be obese/overweight than their counterparts with siblings?

Family planning policy in China has resulted in a large number of one-child families. According to Becker's "quantity-quality trade-off" theory there is an inverse relationship between the number of children in a family, and spending per child. We test whether this has led to significant differences in the height, weight and BMI of only-children compared with children with siblings in China using 4414 observations derived from four recent waves (2004, 2006, 2009, and 2011) of the China Health and Nutrition Survey. We use propensity score matching and instrumental variables to control for the possible endogeneity of the number of siblings. Results show that only-children are significantly heavier (1.88 %-3.86 %), and have higher BMI (2.59 %-3.50 %). Moreover, they are more likely to be obese than children with siblings (2.33 %-3.00 %). Further analysis shows that these differences in health outcomes might be attributable to higher consumption of animal-source food (23.90-27.13 g), a higher frequency of eating western fast food (0.48-0.70 times/3-month) and drinking sweetened soft drinks (0.29-0.36 times/month), a higher share of meals eaten away from home (4.67 %-5.31 %), and more sedentary activity (20.04-34.35 minutes/week) by only children. Our study indicates that the growing share of only children due to China's family planning policies also contributes to the increasing prevalence of overweight and obesity in China. This policy has been eased in recent years, which might slow the increase in the prevalence of overweight and obesity and thus reduce the corresponding health burden for Chinese society as a whole.

Association between Food Preferences, Eating Behaviors and Socio-Demographic Factors, Physical Activity among Children and Adolescents: A Cross-Sectional Study

The prevalence of overweight and obesity is a serious health issue among children and adolescents worldwide. This study aimed to investigate factors influencing weight status-associated food preferences and eating behaviors. A cross-sectional study was conducted to collect data from 2578 pairs of Chinese children and parents in five cities from December 2018 to March 2019. There was an increase in consumptions of processed seafood, nuts and dried fruit/vegetables, and fruit/vegetable juice, but a reduction of consuming puffed and processed meat products, sugar/artificially sweetened beverages and milk tea, and picky eating. These food preferences differentiate between sexes. Picky eating behavior was greatly presented in children of lower educated mothers or heavy-smoking fathers. Children of the lower educated fathers consumed less processed seafood and dairy products, and those of the heavy-smoking fathers consumed more puffed products, but less fruit/vegetable juice, and had greater snack preference. The father’s body mass index(BMI)status was also positively associated with unhealthy behaviors. Those who exercised daily longer showed better eating behaviors, and picky eating and fast-food lovers likely occurred in higher-income families. Our study provides an insight into that fathers being educated for health-conscious advice and physical activity may be the potential strategies to foster their children’s healthy eating patterns. Their efficacy needs to be further investigated.

Understanding Adolescents' Need Support, Need Satisfaction, and Health-Related Outcomes: A Self-Determination Health Behavior Perspective

School physical education (PE) as an important social context can promote adolescents’ physical health and contributes to their mental health. Guided by the self-determination health behavior model, the study aimed to examine a structural mediation model to investigate the relationships among perceived need support from PE teachers, psychological need satisfaction, and adolescents’ health-related outcomes. Participants were 300 adolescents (M_age = 14.48; 50.3% girls) recruited from five middle schools in Shanghai, China. They completed previously validated questionnaires assessing their perceived need support from PE teachers, psychological need satisfaction, leisure time physical activity (LTPA), and health-related quality of life (HRQOL). The hypothesized model demonstrated a good fit (χ²/df = 3.4, p < 0.01; Root Mean Square Error of Approximation (RMSEA) = 0.09; Standardized Root Mean Square Residual (SRMR) = 0.06; Bentler–Bonett Nonnormed Fit Index (NFI)= 0.92; Comparative Fit Index (CFI) = 0.94; 90% Confidence Interval (CI) [0.07, 0.11]). The findings indicated that three basic psychological needs can be satisfied by perceived need support from PE teachers, and psychological need satisfaction was positively associated with health-related outcomes such as LTPA and HRQOL. In addition, psychological need satisfaction mediated the relationship between perceived need support from PE teachers and health-related outcomes such as LTPA and HRQOL in the present study. The findings supported the theoretical tenets of the self-determination health behavior model and its generalizability among Chinese adolescent students.

Parental Perceptions of Obesity in School Children and Subsequent Action

Background: Despite perceiving their child as being above a healthy weight, many parents do not intervene. Little is known about the factors influencing parental action. We assessed parental perception of child's weight status, the prevalence of mitigating parental action, and the underlying factors. Methods: We studied 20,242 children and adolescents from 6 centers across China. Anthropometry was measured by research nurses. Parents answered questionnaires, including their perception of their child's weight status, and any subsequent weight treatment. Results: A total of 3254 children had obesity (16.1%), with 63.0% correctly perceived as overweight by their parents. These children were more likely to be older (≥8 years; p < 0.0001), have severe obesity [adjusted relative risk (aRR) 1.41; p < 0.0001], and have mothers with overweight/obesity (aRR 1.15; p < 0.0001). In particular, parents of children aged <8 years were over five times more likely to perceive their child with overweight/obesity as "thin" than parents of teenagers. Conversely, girls, older children/adolescents, and urban youth were more likely to be wrongly perceived by parents as having an overweight issue. Only one in four children (27.8%) with available information received treatment for their perceived weight problem. Children with severe obesity were more likely to be treated (aRR 1.34; p < 0.0001), as were children of mothers with overweight/obesity (aRR 1.18; p = 0.002). Conclusions: Only one in four Chinese children perceived as overweight by their parents received treatment for their weight problem. Given that overweight/obesity in childhood tracks into adulthood and many parents did not intervene despite perceiving an overweight problem in their child, interventions for childhood obesity need to extend beyond parental perception of children's weight status.

Correlations between obstructive sleep apnea and adenotonsillar hypertrophy in children of different weight status

The present study aimed to evaluate the relationship between OSA and adenotonsillar size in children of different weight status. A total of 451 patients aged 2–13 years with suspected OSA were retrospectively enrolled in the study. Correlations between the apnea-hypopnea index (AHI) and adenotonsillar size in different weight status were investigated. The adenoidal/nasopharyngeal (A/N) ratio of underweight children was significantly higher than that of normal-weight children (P = 0.027). Both adenoid and tonsil size were positively correlated with logAHI in children of normal weight (r = 0.210, P = 0.001; and r = 0.212, P = 0.001) but uncorrelated in the other groups. Gender (OR = 1.49, 95% CI: 1.01–2.20, P = 0.043), obese (OR = 1.93, 95% CI: 1.10–3.40, P = 0.012), A/N ratio (OR = 1.55, 95% CI: 1.28–1.88, P < 0.001) and tonsil size (OR = 1.36, 95% CI: 1.18–1.57, P < 0.001) were all associated with the severity of OSA. Adenotonsillar hypertrophy contributed to OSA in normal-weight children. In children of abnormal weight, instead of treatment for adenotonsillar hypertrophy, appropriate treatments for other factors are required.

School education and childhood obesity: A systemic review

Childhood obesity prevalence is shooting up at a phenomenal rate worldwide, leading to long-term devastating consequences. A great number of studies have investigated factors contributing to the increase in BMI of children and adolescents. School-based, home-based and clinic-based solutions have been suggested as possible viable strategies, among which school-based interventions is believed to produce a noticeable effect on a massive scale. However, the question of whether school interventions, especially school education exert significant impact on childhood obesity or not, is left with mixing results. This article aims to holistically review the relationship between school education and childhood obesity. Various factors are covered, including health education, nutrition education, school nutrition, physical education, teachers' awareness, teaching practice and school stress, In all, school education is not the answer to childhood obesity but just part of it. More attempts from other stakeholders (parents, community, policy makers, researchers, etc.) should be made in order to solve this complicated puzzle.

Differences in Cardiorespiratory Fitness between Chinese and Japanese Children and Adolescents

Background: This study aimed to compare the difference in cardiorespiratory fitness between Chinese and Japanese children and adolescents. Methods: Participants comprised 9025 children and adolescents aged 7–18 years from China and Japan. Cardiorespiratory fitness (CRF) was measured by performance in the 20 m shuttle run test (20mSRT) and estimated maximal oxygen consumption (VO_2max). Differences in CRF between countries were evaluated by t-tests. Centile curves for the 20mSRT and VO_2max values were constructed for Chinese and Japanese children and adolescents, respectively, using the Lambda Mu and Sigma (LMS) method. Results: (1) For most of the age groups, the 20mSRT and VO_2max performances among Chinese participants were lower than among Japanese participants. (2) Japanese children had the most apparent gains in P₁₀, P₅₀, and P₉₀ VO_2max values in primary school; however, they gradually decreased in middle school. For Chinese girls, the P₁₀, P₅₀, and P₉₀ VO_2max values decreased gradually with age. (3) The VO_2max value among Japanese children increased; however, it decreased or remained flat among Chinese children in primary school. Conclusions: CRF among Chinese participants was lower than among Japanese participants while the VO_2max value showed different trends in primary school. Effective measures should be taken to improve CRF among children and adolescents.

Is the decline of active travel to school unavoidable by-products of economic growth and urbanization in developing countries?

BACKGROUND

Economic growth and urbanization may contribute to the decline of active travel to school (ATS). We aim to explain the change of ATS in China between 1997 and 2011 and to predict the prevalence of ATS in China within the next 30 years using various scenario.

METHODS

We developed a system dynamics model to study ATS and the model assumes the prevalence of ATS is determined by the dynamic interaction of four exogenous and eight endogenous variables.

RESULTS

The simulated prevalence of ATS is roughly consistent with empirical data. Economic development and urban sprawl are more influential than urban design and crime in terms of ATS. Under a relatively reasonable scenario, the prevalence of ATS is projected to decrease from 73% in 2011 to 65% in 2014, and the prevalence of childhood overweight & obesity is projected to increase from 24% in 2011 to 34% in 2041. With the maintaining of economic development grow, to control urban sprawl is the most effective measure to promote ATS and decrease childhood obesity.

CONCLUSIONS

Overall, the model enabled us to conduct experiments to test the possible effects of changing one or more factors taking into account their dynamic interrelationship, and our study may provide implications for policy intervention.

Comparison of various anthropometric indices in predicting abdominal obesity in Chinese children: a cross-sectional study

Background

Former evidence regarding reference values of abdominal fat percentage (AFP) and optimal anthropometric indicators in predicting abdominal obesity measured by dual-energy X-ray absorptiometry (DXA) scan in Chinese children were scarce.

Methods

A total of 452 Chinese children aged 6–9 years were included in this cross-sectional study. Abdominal fat and lean mass were measured by a DXA scan, and AFP were calculated. Anthropometric indicators including body mass index (BMI), chest circumference (CC), waist circumference (WC) and hip circumference (HC) were measured, waist-to-hip ratio (WHR), waist-to-height ratio (WHtR) was also calculated.

Results

By defining abdominal obesity as those with an AFP ≥ 85th percentile, the cutoffs values are 24.80, 30.29, 31.58, 31.86% in boys, and 25.02, 30.32, 31.66, 31.79% in girls, for children aged 6, 7, 8, and 9 years old, respectively. All anthropometric indicators were independently and positively associated with AFP (P all < 0.01). In girls, BMI was found to be the optimal predictors of childhood abdominal obesity. The values of area under curves (AUCs) were significantly higher (P all < 0.05) than other anthropometric indicators, except for WHtR (AUCs value: 0.886). However, in boys, WHtR instead of BMI, provided the largest AUCs value (0.922) in predicting abdominal obesity, followed by BMI ((AUCs value: 0.913).

Conclusion

This study provides reference values of AFP measured by DXA in Chinese children aged 6–9 years. BMI and WHtR tend to be the optimal anthropometric indicators in predicting abdominal obesity in Chinese girls and boys, respectively.

Geographical variation and urban-rural disparity of overweight and obesity in Chinese school-aged children between 2010 and 2014: two successive national cross-sectional surveys

PURPOSE

The urban-rural disparity for childhood overweight and obesity shows different patterns in most countries. This study aimed to examine the recent trend of urban-rural disparity for childhood overweight and obesity at national and subnational levels in Chinese children from 2010 to 2014.

DESIGN

Two successive national cross-sectional studies. Overweight and obesity were classified using Chinese national age-specific and sex-specific body mass index reference. The prevalence of overweight and obesity was compared between urban and rural areas at national and subnational levels.

SETTING

Thirty-one provinces in China.

PARTICIPANTS

Data were obtained from the Chinese National Survey on Students' Constitution and Health in 2010 and 2014 with 215 214 (107 741 in 2010 and 107 473 in 2014) children aged 7-12 years.

RESULTS

The overweight and obesity prevalence increased from 17.1% in 2010 to 22.5% in 2014. The overweight and obesity prevalence in both urban and rural areas was higher in the eastern provinces but lower in the western provinces. The urban-rural disparity in overweight and obesity decreased steadily from 2010 to 2014 (1.79 to 1.42 for prevalence OR). There was greater urban-rural disparity in western China than eastern China. A reversal occurred in 2014 in several eastern provinces where the overweight and obesity prevalence in rural children surpassed that of their urban peers.

CONCLUSIONS

A narrowing urban-rural disparity and the reversal signal between urban and rural areas in overweight and obesity would contribute to a growing proportion of obese children in rural areas. Therefore, urgent region-specific policies and interventions with a forward-looking approach should be considered for Chinese children, especially in rural areas.