25-year trends in gender disparity for obesity and overweight by using WHO and IOTF definitions among Chinese school-aged children: a multiple cross-sectional study

Prevalence and associated factors of overweight in Chinese adolescents: A cross-sectional study

Background and Aim

Obesity has been a global public health issue due to the increasing mortality rate and prevalence among children. However, there are scarce studies on obesity prevalence in Hong Kong children. The study aims to identify the risk factors of obesity among primary and secondary school students by assessing the relationship between sociodemographic factors, health-related behaviors, and social relationships.

Methods

Self-administrated surveys were collected from 30 primary schools and 25 secondary schools participating in the "Quality Education Fund Thematic Network on Health Schools" project. Descriptive analysis was conducted to examine the proportions of different characteristics and to compare the disparity between primary and secondary school students with obesity.

Results

A total of 4884 responses were collected. A larger proportion of primary school students with obesity were male (adjusted odds ratio [aOR]: 2.55, 95% confidence interval [CI]: 1.77-3.67, p < 0.001) and actively gamed (aOR: 1.64, 95% CI: 1.07-2.51, p = 0.024). Secondary school students with obesity were male (aOR: 1.61, 95% CI: 1.21-2.13, p = 0.001), had poor self-perceived academic performance (aOR:1.51, 95% CI: 1.10-2.08, p = 0.011) and expressed higher life satisfaction (family) (aOR: 1.13, 95% CI: 1.01-1.26, p = 0.032). There were negative associations found between obesity and physical activity, high consumption of sugary drinks, chocolate or candies, and insufficient consumption of vegetables.

Conclusion

Male sex, physical inactivity, low self-perecived academic performance, and poor dietary behaviors were the risk factors for obesity among primary and secondary school students. The findings highlighted the importance of identifying younger individuals who were at risk of becoming clinically obese. Further studies should explore the effectiveness of various interventions through longitudinal study.

Matching actions to needs: shifting policy responses to the changing health needs of Chinese children and adolescents

China is home to the second largest population of children and adolescents in the world. Yet demographic shifts mean that the government must manage the challenge of fewer children with the needs of an ageing population, while considering the delicate tension between economic growth and environmental sustainability. We mapped the health problems and risks of contemporary school-aged children and adolescents in China against current national health policies. We involved multidisciplinary experts, including young people, with the aim of identifying actionable strategies and specific recommendations to promote child and adolescent health and wellbeing. Notwithstanding major improvements in their health over the past few decades, contemporary Chinese children and adolescents face distinct social challenges, including high academic pressures and youth unemployment, and new health concerns including obesity, mental health issues, and sexually transmitted infections. Inequality by gender, geography, and ethnicity remains a feature of health risks and outcomes. We identified a mismatch between current health determinants, risks and outcomes, and government policies. To promote the health of children and adolescents in China, we recommend a set of strategies that target government-led initiatives across the health, education, and community sectors, which aim to build supportive and responsive families, safe communities, and engaging and respectful learning environments. TRANSLATION: For the Chinese translation of the abstract see Supplementary Materials section.

Trends in the prevalence of obesity, overweight, and thinness among schoolchildren aged 7-14 years from southern Brazil (2002-2019)

OBJECTIVE

To analyze the obesity, overweight, and thinness trends among Brazilian schoolchildren by sex, age group, and type of school according to World Health Organization (WHO) and International Obesity Task Force (IOTF) criteria.

METHODS

We conducted four surveys between 2002 and 2018/19 involving schoolchildren aged 7-14 years from a state capital in southern Brazil. Weight status was classified using both WHO and IOTF criteria.

RESULTS

In the total sample, obesity prevalence based on the IOTF and the WHO criteria were 72% and 44% higher in 2018/19 compared with 2002, respectively. Over the whole period, the obesity prevalence increased among children (WHO: 10.1% vs. 14.1%; IOTF: 5.0% vs. 8.3%), and those from public schools (WHO: 10.5% vs. 16.4%; IOTF: 5.6% vs. 10.1%). There was no significant reduction in thinness prevalence over the analyzed period.

CONCLUSION

Obesity prevalence remains on an upward trend in a state capital in southern Brazil, especially among children from public schools. A higher prevalence of overweight and obesity was observed using the WHO criteria compared with IOTF criteria.

Trends of obesity and overweight among children and adolescents in China

BACKGROUND

Recent decades have shown a rapid increase in the prevalence of overweight and obesity among Chinese children based on several national surveys. Restrictions due to the coronavirus disease 2019 outbreak have worsened its epidemiology. This review updates the trends in the prevalence of overweight and obesity among Chinese children and adolescents and analyzes the underlying reasons to provide evidence for better policy making.

METHODS

Studies published in English and Chinese were retrieved from PubMed, Google Scholar, China National Knowledge Infrastructure and Wanfang.

RESULTS

The prevalence of overweight and obesity has been increasing for decades and varies with age, sex and geography but is more pronounced in primary school students. The increase in obesity in boys appeared to be slower, whereas that in girls showed a declining trend. The northern areas of China have persistently maintained the highest levels of obesity with a stable trend in recent years. Meanwhile, the prevalence in eastern regions has dramatically increased. Notably, the overall prevalence of obesity in children has shown a stabilizing trend in recent years. However, the occurrence of obesity-related metabolic diseases increased. The effect of migrants floating into east-coast cities should not be neglected.

CONCLUSIONS

The high prevalence of overweight and obesity among Chinese children and adolescents persists but with varying patterns. Obesity-related metabolic diseases occur more frequently despite a stable trend of obesity. Multiple factors are responsible for the changing prevalence. Thus, comprehensive and flexible policies are needed to effectively manage and prevent the burden of obesity and its related complications.

Association between Dietary Behavior and Overweight and Obesity among Chinese Students: A Cross-Sectional Study

OBJECTIVES

To investigate the prevalence of overweight and obesity among Ningbo students and explore the association between students' dietary behavior and overweight and obesity.

MATERIALS AND METHODS

A total of 7299 students were recruited, including 3755 males and 3544 females. A questionnaire on student health status and influencing factors was used to investigate dietary behavior. Logistic regression analysis investigated the relationship between dietary behavior and overweight and obesity. Age, gender, area, grade, sleep duration, and physical activity were adjusted in the multivariate regression models.

RESULTS

This study revealed that the prevalence of overweight and obesity in Ningbo students was 16.14% and 9.88%, respectively. The logistic regression analysis results showed that regular consumption of sugary beverages was associated with a higher risk of being overweight (OR = 1.256, 95% CI: 1.023-1.542, p = 0.029). The research indicated that skipping breakfast was considered a risk factor for obesity (OR = 2.102, 95% CI: 1.087-4.065, p = 0.027). After adjusting for age, gender, area, and grade and continuing to adjust for sleep duration and physical activity, the results showed that consuming fried food at least once a day increased the risk of obesity (OR = 1.494, 95% CI: 1.050-2.125, p = 0.026; OR = 1.516, 95% CI: 1.065-2.158, p = 0.021, respectively). This study found that the frequency of breakfast and the consumption of fried food, fresh vegetables, and fruits were not significantly associated with being overweight (p > 0.05).

CONCLUSIONS

This study indicated that dietary behavior was related to overweight and obesity among Ningbo students. Further studies and more government support are required to confirm this study's findings and address the current overweight/obesity problems.

Trends of overweight and obesity prevalence in school-aged children among Henan Province from 2000 to 2019

Objectives

Overweight and obesity are harmful to human health. However, the latest trends of Chinese childhood overweight and obesity prevalence are not available. The aim of this study was to examine the trends from 2000 to 2019 among students in China.

Methods

We analyzed data of 66,072 students in the Chinese National Survey on Students' Constitution and Health from 2000 to 2019. Overweight and obesity were defined based on the standard formulated by the International Obesity Task Force (IOTF standard), the World Health Organization (WHO standard), and the Working Group on Obesity in China (WGOC standard), respectively. The χ²-test was used to test the trends of overweight and obesity prevalence and logistic regression was conducted to evaluate the prevalence odds ratios of boys vs. girls and urban vs. rural areas.

Results

The prevalence of obesity/overweight and obesity combined was 6.03/23.58% (IOTF standard), 10.56/25.88% (WGOC standard) and 10.75/29.69% (WHO standard) in 2019. From 2000 to 2019, according to the WGOC standard, the prevalence increased from 2.51 to 10.56% for obesity and increased from 9.81 to 25.88% for overweight and obesity combined (P for trend < 0.001). Obesity/overweight and obesity were greater problems in boys than girls and urban than rural areas, but urban-rural differences decreased over time.

Conclusion

Overweight and obesity prevalence increased significantly in children and adolescents in China from 2000 to 2019. The prevalence of overweight and obesity in rural areas may contribute to a large percentage of children with overweight and obesity.

Lower fitness levels, higher fat-to-lean mass ratios, and lower cardiorespiratory endurance are more likely to affect the body mass index of Saudi children and adolescents

Background

Several studies suggest that health-related physical fitness may play a prominent role in preventing obesity in children and adolescents.

Objectives

The present study examined fitness levels using five components of health-related fitness in Saudi students aged 10-17 years (fat-to-lean mass ratio, cardiorespiratory endurance, upper body strength and endurance, abdominal muscle strength and endurance, and flexibility). Subsequently, the association between BMI and a health-related fitness index (HR-PFI) based on the five fitness components was investigated.

Methods

The study was conducted on 1,291 students with a mean age of 12.95 ± 1.72 years. Participants included 1,030 boys aged 12.80 ± 1.79 years, with 479 young boys (11.24 ± 0.81b years), and 551 adolescents (14.16 ± 1.21 years). Moreover, the study examined 261 girls averaging 13.54 ± 1.2 years old, with 66 young girls (11.92 ± 0.27 years), and 195 teenage girls (14.09 ± 0.85 years). Each participant's health-related fitness level was assessed by the following tests: Bioelectrical Impedance Analyzer (BIA) for body composition, one-mile run/walk test for cardiorespiratory endurance, curl-up test for abdominal muscle strength and endurance (AMSE), push-up test for upper body strength and endurance (UBSE), and back-saver sit-and-reach test for flexibility.

Results

The overall prevalence of overweight and obesity was 10.4 and 24.7% in boys and 10 and 8.4% in girls, respectively. The mean Z-scores of performances decreased from the underweight to the obese groups. BMI was positively associated with the ratio of fat mass to lean mass and negatively associated with cardiorespiratory endurance in the overall group of participants as well as in the subgroups by sex and age categories. BMI was also negatively associated with flexibility and HR-PFI in the total group, UBSE, AMSE, and HR-PFI in prepubertal boys, and UBSE in prepubertal girls. The coefficient of determination values was 0.65 in the total group, 0.72 in prepubertal boys, 0.863 in adolescent boys, 0.956 in prepubertal girls, and 0.818 in adolescent girls.

Conclusions

Overall health-related physical fitness, fat-to-lean mass ratio, and cardiorespiratory endurance are the factors that most affect BMI in Saudi students aged 10 to 17.

İstanbul'da 6-15 Yaş Arası Çocuklarda Obezite Prevalansı

Amaç: Bu araştırma, İstanbul'un bir ilçesinde 6-15 yaş arası çocuklarda obezite prevalansını ve beslenme alışkanlıklarını değerlendirmeyi amaçlamaktadır.Yöntem: Bu araştırma, İstanbul'un Avcılar ilçesinde 19 ilköğretim okulunda 6-15 yaş arası 2452 öğrenci ile gerçekleştirilen kesitsel tipte bir araştırmadır. Çocukların beslenme alışkanlıkları ve besin tüketim sıklıkları hakkında yüz yüze anket uygulanmıştır. Çocukların boy uzunluğu, vücut ağırlığı, bel ve kalça çevresi ölçümleri alınmıştır. Çocuklar Z-skorlarına göre sınıflandırılmıştır. İstatistikler SPSS 21 programı kullanılarak yapılmıştır.Bulgular: Öğrencilerin toplam %47.8'i erkek, %52.2'si kızdır. Öğrencilerin yaşlarının ortalaması 9.47±2.21, ortalama BKİ ise 18.7±3.73 kg/m2’dir. Fazla kiloluluk ve obezite prevalansı sırasıyla %20.3 ve %13.2 bulunmuştur. 9 yaşındakilerin obezite prevalansı en yüksek düzeydedir ve erkeklerde kızlara göre daha fazla obezite görülmüştür (p&lt;0,001). Obez olan ve obez olmayan öğrenciler arasında ders çalışırken ve televizyon izlerken atıştırma ve bazı besinleri tüketme sıklığı açısından anlamlı fark bulunmuştur (p&lt;0.05).Sonuç: Her üç çocuktan birinin normalden fazla kilolu olduğu bulunmuştur. Ulusal ve uluslararası politikaların yanı sıra bölgesel ve yerel takipler ile gerekli önlemlerin alınması çocukluk çağı obezitesinin kontrolünde faydalı olabilir.

Prevalence and associated factors of overweight and obesity among primary school children: a cross-sectional study in Thanhhoa City, Vietnam

OBJECTIVE

To determine the prevalence and associated factors of overweight and obesity among primary school children (6-11 years old) in Thanhhoa city in 2021.

DESIGN

Cross-sectional study.

SETTING

Seven primary schools in Thanhhoa city, Vietnam.

PARTICIPANTS

782 children (and their parents).

PRIMARY AND SECONDARY OUTCOME MEASURES

Two-stage cluster random sampling was used for selecting children and data were collected from January to February 2021. A self-administrated questionnaire was designed for children and their parents. Children's height and weight were measured and body mass index (BMI)-for-age z-scores were computed using the WHO Anthro software V.1.0.4. Data were analysed using R software V.4.1.2. The associations between potential factors and childhood overweight/obesity were analysed through univariate and multivariate logistic regression analyses. Variables were selected using the Bayesian Model Averaging method.

RESULTS

The prevalence of overweight/obesity among primary school children in Thanhhoa city was 35.93% (overweight 21.61% and obesity 14.32%). The proportion of overweight girls was nearly equal to that of boys (20.78% and 22.52%, respectively, p=0.6152) while the proportion of boys with obesity was four times as many as that of girls (23.86% and 5.62%, respectively, p<0.0001). Child's sex was the factor significantly associated with childhood overweight/obesity. Boys had double the risk of being overweight/obese than girls (adjusted OR: aOR=2.48, p<0.0001). Other potential factors which may be associated with childhood overweight/obesity included mode of transport to school, the people living with the child, mother's occupation, father's education, eating confectionery, the total time of doing sports, and sedentary activities.

CONCLUSION

One in every three primary school children in Thanhhoa city were either overweight or obese. Parents, teachers and policy-makers can implement interventions in the aforementioned factors to reduce the rate of childhood obesity. In forthcoming years, longitudinal studies should be conducted to determine the causal relationships between potential factors and childhood overweight/obesity.

The Influence of a School Social Network Intervention on Adolescent's Health Behaviors: A Gender-Specific Agent-Based Model

Introduction

Adolescence is a crucial stage for health behavior development, which is associated with health in adulthood. School closures caused by the coronavirus disease 2019 (COVID-19) pandemic have exposed adolescents to an increased risk of obesity due to a lack of physical activity. Although social network interventions provide an effective approach for promoting health-related behavior, current practices neglect gender differences in adolescent behavioral patterns and emotional preferences. The aim of this study was to examine the effectiveness of centrality-based methods integrated with of gender contexts in a social network intervention to improve adolescent's health behavior.

Methods

We developed an agent-based model (ABM) that supports the small-world characteristics of adolescent social networks. Health-related data for junior middle school students (n = 234, 48% girls) were collected in November 2018, 2019 and 2020 in Tianjin, China. We simulated multiple network-based interventions with different criteria for influential agents (i.e., betweenness centrality, closeness centrality, eigenvector centrality, and PageRank) and a random condition. The rules for generating peer influence and accelerating behavioral changes were based on the diffusion of innovations theory, with gender specifications.

Results

After the school closures, there was a significant increase in the prevalence of overweight and obesity among adolescents, with a greater increase in girls than in boys (+8.85% vs. +1.65%, p < 0.001). Simulations showed that centrality-based network interventions were more effective than the random condition (average 6.17% per tick vs. 5.22% per tick, p < 0.05), with a higher efficiency in girls than boys (average 3.68% vs. 2.99% per tick, p < 0.05). PageRank outperformed other centrality conditions at the population level (6.37% per tick, p < 0.05). In girls, betweenness centrality was the best method (3.85% per tick, p < 0.05), while in boys, PageRank still had the greatest efficiency (3.21% per tick, p < 0.05).

Conclusions

We found evidence for gender differences in the negative impact of COVID-19-related school closures and the potential for centrality-based social network interventions to affect adolescent health behavior. Therefore, we emphasize the importance of gender-specific targeting strategies to further promote health-related school programs in the post-pandemic era.

The Gender Gap in Life Expectancy in Urban and Rural China, 2013–2018

Background

Gender differences in mortality are embedded within mortality transitions. Rural residents generally lag behind their urban counterparts in the transitions. The study objective is to identify major causes of death that drive gender differences in mortality in urban and rural China.

Methods

We use age-, gender-, urban-rural- and cause-specific mortality data (2013–2018) derived from the national mortality surveillance system that covered about 24% of the Chinese population. We apply Arriaga's method to decompose age- and cause-specific contributions to the gender gap in life expectancy at birth. Analyses are stratified by urban-rural residence.

Results

Women had a higher life expectancy at birth than men in both urban and rural areas. Cancers, cardiovascular disease, external causes, and respiratory disease accounted for more than 90% of the gender gap in both areas during 2013–2018. In urban areas, the gender gap decreased from 5.17 years in 2013–2015 to 4.98 years in 2016–2018. In rural areas, the gender gap stayed rather constant (2013–2015: 5.68 years; 2016–2018: 5.65 years). Traffic accidents, among external causes, contributed the most to decreasing the gender gap (urban: −0.07 years; rural: −0.10 years), especially in the 0–44 age group. However, the decrease in the gender gap was counteracted by an increase in the gender gap attributable to ischemic heart disease (urban: +0.05 years; rural: +0.08 years) and lung cancer (urban: +0.02 years; rural: +0.05 years) in older age groups. The gender gap attributable either to cerebrovascular disease or to chronic lower respiratory disease decreased in urban areas but increased in rural areas.

Conclusions

The urban-rural variations in the cause-specific contributions to the gender gap in China suggest the necessity of implementing urban-rural-specific interventions to improve population health and health equity.

Prevalence of Overweight and Obesity and Associated Diet-Related Behaviours and Habits in a Representative Sample of Adolescents in Greece

Excessive body weight during adolescence represents a significant public health problem worldwide. Identifying factors associated with its development is crucial. We estimated the prevalence of overweight and obesity in a representative sample of 11, 13 and, 15-year-olds living in Greece and explored the association with diet-related behaviours and habits. Self-reported data on weight, height, diet-related behaviours and habits were used from 3816 students (1898 boys, 1918 girls) participants in the Greek arm of the international Health Behaviour in School-Aged Children (HBSC) study during 2018. Overweight and obesity were defined using the 2007 WHO growth charts classification. Prevalence of overweight was 19.4% in the total sample, 24.1% for boys and 14.7% for girls, and prevalence of obesity was 5.3% in the total sample, 7.3% for boys and 3.4% for girls, respectively. In the total sample, overweight (including obesity) was positively associated with male gender, low family affluence, skipping breakfast, and being on a diet, and inversely associated with age and being physically active. Eating rarely with the family was positively associated with overweight only among boys and eating snacks/meals in front of screens only among girls. No association was noted for eating in fast-food restaurants, consuming vegetables, fruits, sweets, and sugar-sweetened beverages.

Screening of central obesity among normal-weight children and adolescents in Shandong, China

The prevalence of central obesity in the total population has been reported in numerous studies. However, information on the prevalence of central obesity within normal-category BMI is scant. In the present study, we examined the profiles of central obesity among normal-weight children and adolescents. A total of 29 516 (14 226 boys and 15 290 girls) normal-weight children and adolescents (excluding underweight, overweight and obesity) aged 7-18 years were included in the final analysis. Central obesity was defined by the international age- and sex-specific cut-offs of waist circumference (WC) and threshold of waist:height ratio (WHtR ≥ 0·5). All subjects were classified into four groups (Q1-Q4) according to the age- and sex-specific quartiles of BMI, those in the upper fourth (Q4) were defined as 'high-normal BMI' and those in the lower fourth (Q1) were defined as 'low-normal BMI'. The prevalence of central obesity as measured by WC was 9·90 (95 % CI 9·41, 10·39) % for boys and 8·11 (95 % CI 7·68, 8·54) % for girls; by WHtR was 2·97 (95 % CI 2·69, 3·25) % for boys and 2·44 (95 % CI 2·20, 2·68) % for girls. Subjects in the Q4 group had a much higher prevalence of central obesity than their counterparts in the Q1 group (P < 0·01). Our findings suggest that the health risks of children with normal-weight central obesity may be missed when BMI is used alone as a measure; it is meaningful to include WC in clinical practice and to include the simple message 'Keep your waist to less than half your height'.

Trends of dental caries in permanent teeth among 12-year-old Chinese children: evidence from five consecutive national surveys between 1995 and 2014

BACKGROUND

Dental caries have a serious impact on general health and well-being; however, there is a lack of relevant data on the development trends of dental caries in permanent teeth among 12-year-old children in China. We aim to assess long-term trends of dental caries in permanent teeth among 12-year-old children in China and identify the susceptible subgroups based on five consecutive national surveys from 1995 to 2014.

METHODS

A total of 88 972 subjects were extracted from five consecutive national surveys (1995, 2000, 2005, 2010, 2014). Standardized dental examinations were conducted and the oral health status of each subject was recorded. The prevalence of Decayed, Missing and Filled teeth (DMF%), mean Decayed, Missing, Filled teeth score (DMFT) and Caries Filling Ratio (CFR) were used as measurement indicators. Cochran-Armitage trend test was used to evaluate the trends in DMF% and CFR, and multivariate linear regression was used to evaluate the trends in DMFT.

RESULTS

A V-shaped fluctuating upward trend in DMF% during 1995-2014 was observed (Z =  - 13.124, P < 0.001), and the DMF% in 1995-2014 was 21.1%, 15.9%, 16.2%, 21.9% and 24.3%. The trend in DMFT was approximately consistent with DMF% (β = 0.057, P < 0.001), but the downward volatility appeared in 2014. The DMFT in 1995-2014 was 0.38, 0.28, 0.31, 0.66 and 0.54. A continuously fluctuant trend in CFR was observed during past two decades (Z = 1.927, P > 0.05), and the CFR in 1995-2014 was 17.4%, 22.8%, 19.3%, 23.4% and 15.6%. The DMF% and DMFT of rural children had a larger absolute increase than that of urban children during 1995-2014 (DMF%-urban: Z =  - 0.242, P > 0.05; DMF%-rural: Z =  - 19.036, P < 0.001; DMFT-urban: β = 0.035, P < 0.001, DMFT-rural: β = 0.077, P < 0.001). The DMF% and DMFT in girls were higher than that in boys at each survey year (P < 0.001). CFR of urban children was higher than that of rural children at each survey year (P < 0.001).

CONCLUSIONS

Over the past 20 years, DMFT and DMF% of 12-year-old children in China presented V-shaped fluctuant upward trends, with a decline trend from 1995 to 2000 and an upward trend from 2000 to 2014. CFR had no significant improvement. The rural children and girls are the more vulnerable groups in the development of dental caries and need to pay priority. Our study supports the continuation of policies to improve children' oral health.

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.

Association between parental socioeconomic status and offspring overweight/obesity from the China Family Panel Studies: a longitudinal survey

OBJECTIVE

To examine the association between parental socioeconomic status (SES) and the risk of offspring overweight/obesity and the changes of the association that occur as children grow older.

DESIGN

We used data from the nationally representative longitudinal survey of the China Family Panel Studies of 2010 and its three follow-up waves in 2012, 2014 and 2016.

PARTICIPANTS

A total of 6724 children aged 0-15 years old were included.

PRIMARY AND SECONDARY OUTCOME MEASURES

Average household income and paternal and maternal education levels were used as SES indicators. Logistic regression model for panel data was used to examine the associations between SES indicators and child overweight/obesity. A restricted cubic spline linear regression model was used to estimate body mass index (BMI) trajectories with child growth across parental SES levels.

RESULTS

Compared with the lowest education level (primary school or less), the ORs for fathers who had completed junior high school, senior high school and junior college or higher were 0.85 (95% CI 0.75 to 0.97), 0.77 (95% CI 0.64 to 0.92) and 0.72 (95% CI 0.55 to 0.93), respectively. The corresponding ORs for mothers were 0.76 (95% CI 0.67 to 0.86), 0.59 (95% CI 0.47 to 0.72) and 0.45 (95% CI 0.34 to 0.60), respectively. A negative association between parental education and offspring overweight/obesity was observed in the first 10 years but not in children 11-15 years old. BMI differences across parental education levels emerged from birth and widened before 6-7 years old, but decreased before adolescence. High average household income was related to a low risk of offspring overweight/obesity but not when parental education level was adjusted for.

CONCLUSION

High parental education levels were associated with a low risk of offspring overweight/obesity, especially before adolescence. Effective approaches need to be adopted in early childhood to reduce socioeconomic differences in overweight/obesity.

Changes in the age-specific body mass index distribution among urban children between 2002 and 2018 in Changsha, China

BACKGROUND

It had been reported that the increase in the prevalence of childhood overweight and obesity in several developed countries over the decade was largely a consequence of changes in the upper end of the body mass index (BMI) distribution. We speculated that the change in BMI distribution among Chinese children is different from that in developed countries. Therefore, we investigated the changes in the BMI distribution among urban children in Changsha, China.

METHODS

A secondary data analysis of the 2002 and 2018 Annual Survey on Students' Constitution and Health from Yuhua District, Changsha City, China was performed. The BMI distribution of children aged 6-15 years (n=72,061) was examined by calculating the BMI value at 5th, 50th, 85th, and 95th percentiles. Differences in the BMI value at the 5th, 50th, 85th, and 95th percentiles between 2002 and 2018 according to age and sex were calculated.

RESULTS

From 2002 to 2018, the standardized rate of underweight decreased from 6.9% to 3.4%, whereas that of obesity increased from 6.1% to 13.8%. The BMI of the population increased over the 16-year period. The greatest change between the years was seen in the 85th percentile, and moderate changes were seen in the 5th and 50th BMI percentiles. Also, the greatest changes in the BMI percentiles were evident at age 12-14 years.

CONCLUSIONS

The whole spectrum of BMI distribution among school-aged children shifted over the 16-year study period, although the increases were more marked in the upper than lower percentiles. Health professionals and health policymakers should develop strategies and interventions aimed at preventing adverse health effects caused by this change.

Sex and gender differences in childhood obesity: contributing to the research agenda

Childhood obesity is a major public health challenge and its prevalence continues to increase in many, but not all, countries worldwide. International data indicate that the prevalence of obesity is greater among boys than girls 5-19 years of age in the majority of high and upper middle-income countries worldwide. Despite this observed sex difference, relatively few studies have investigated sex-based and gender-based differences in childhood obesity. We propose several hypotheses that may shape the research agenda on childhood obesity. Differences in obesity prevalence may be driven by gender-related influences, such as societal ideals about body weight and parental feeding practices, as well as sex-related influences, such as body composition and hormones. There is an urgent need to understand the observed sex differences in the prevalence of childhood obesity; incorporation of sex-based and gender-based analysis in all childhood obesity studies may ultimately contribute to improved prevention and treatment.

Increasing trends in incidence of preterm birth among 2.5 million newborns in Guangzhou, China, 2001 to 2016: an age-period-cohort analysis

Background

The incidence of preterm birth (PTB, < 37 weeks of gestation) has been increasing in China and many other countries in recent years. However, the causes of the increase were not well understood. The current study aims to examine the contribution of maternal age, period of delivery, and maternal birth cohorts to long-term trends in preterm birth in Guangzhou, China.

Methods

In a retrospective population-based study, data were obtained from 2,535,000 singleton live births with 20–43 gestational weeks from 2001 to 2016 and recorded in the Guangzhou Perinatal Health Care and Delivery Surveillance System, in China. The age-period-cohort models were applied to investigate the temporal changes in incidences of PTB, stratified by parity.

Results

The incidence of preterm birth steadily increased from 5.1% in 2001 to 5.9% in 2016, with larger rise in primiparous mothers (from 5.0 to 5.9%) compared to multiparous mothers (from 5.6 to 5.9%). A J-shaped and a V-shaped relationship were found between maternal age and PTB among primiparous and multiparous mothers, respectively. A linear cohort effect was found among primiparous mothers with the lowest risk of PTB [risk ratio (RR) = 0.81, 95% confidence interval (CI): 0.74 to 0.89] in 1961 and the highest risk (RR = 1.06, 95% CI: 1.00 to 1.13) in 1997 compared to the mothers born in 1981. An inverse U-shaped association between maternal birth cohort and PTB was found in multiparous mothers. There were weak decreasing period effects on the trend of overall PTB among multiparous mothers and on the trend of extremely (< 27 weeks) or very (28–31 weeks) PTB among both parity groups during the period of 2001–2012.

Conclusions

Our findings showed the PTB incidences had been increasing in the past 16 years in Guangzhou, China and both maternal age and cohort effects contributed to these trends. Further studies are recommended on the impact of altered maternal age and parity on premature births and corresponding public education and public health policies.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s12889-020-09739-6.

Identification of the most appropriate existing anthropometric index for home-based obesity screening in children and adolescents

OBJECTIVES

Home-based self-screening and monitoring for obesity is particularly valuable for the prevention and control of chronic diseases. This study aimed to identify an anthropometric index suitable for home-based obesity screening in children and adolescents.

STUDY DESIGN

The design of this study is a cross-sectional study.

METHODS

A total of 14,042 students (6-17 years) from the Qibao Community, Minhang District, Shanghai, were studied in 2018. The percentage body fat (PBF), height, weight, waist circumference (WC) and hip circumference were measured. Body mass index (BMI), triponderal mass index (TMI), body adiposity index (BAI), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) were calculated. Partial correlation analysis was used to evaluate the relationships between these indices and PBF, and receiver operating characteristic (ROC) curves were used to evaluate their performance for obesity screening.

RESULTS

BMI, TMI, WC and WHtR were found to strongly correlate with PBF (r ≥ 0.830, all P < 0.001). The optimal index for obesity screening in children (6-11 years) was BMI (area under the ROC curve [AUC] = 0.980 for boys and 0.981 for girls) and in adolescents (12-17 years) was TIM (AUC = 0.976 for boys and 0.945 for girls); however, the optimal cut-off values for BMI and TMI differed among the subgroups. The ROC curve analysis showed that WHtR had similar cut-off values in each subgroup (0.45 for boys of 6-11 years and 0.43 for the other subgroups), excellent performance in children (AUC>0.90) and good performance in adolescents (AUC = 0.960 for girls and 0.878 for boys).

CONCLUSIONS

Owing to its accuracy and stable cut-off value for defining obesity, WHtR should be recommended for home-based obesity screening in children and adolescents.

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.

Comparison of different BMI cut-offs to screen for child and adolescent obesity in urban China

Objectives:

To determine which set of BMI cut-offs is the most appropriate to define child and adolescent obesity in urban China.

Design:

A cross-sectional study was carried out between 1 November and 31 December in 2017.

Setting:

Community Healthcare Center in Minhang District, Shanghai, China.

Participants:

A total of 12 426 children and adolescents aged 7–17 years were selected by cluster random sampling. Bioelectrical impedance analysis was the gold standard to measure body composition.

Results:

Comparisons of three sets of BMI cut-offs by sensitivity and κ value revealed that the Working Group on Obesity in China (WGOC) (sensitivity 39·9–84·0 %; κ 0·51–0·79) and WHO (sensitivity 25·5–74·5 %; κ 0·35–0·78) cut-offs were not superior to the International Obesity Task Force (IOTF) (sensitivity 47·9–92·4 %; κ 0·58–0·85) cut-offs across all subgroups. The WGOC and WHO cut-offs yielded higher misclassification rates, in the worst case, categorising 11·2 % of girls with high adiposity as normal and 44·4 % of them as overweight, while the IOTF cut-offs categorised 2·3 % as normal and 30·7 % as overweight. Individuals who were classified by the IOTF cut-offs as overweight had the lowest ratios of high adiposity (4·2–41·6 %) than by the BMI cut-offs for each subgroup. Among pubertal girls, none of the BMI-based cut-offs indicated excellent agreement with body fat percentage, and κ value of the WHO cut-offs (0·35 (95 % CI 0·29, 0·41)) was lower than the other two sets of BMI cut-offs (all P < 0·001).

Conclusions:

The IOTF cut-offs for Asian should be recommended for child obesity screening in urban China. Pubertal individuals need a more accurate indicator of obesity screening.

Interaction of the CMTM7 rs347134 Polymorphism with Dietary Patterns and the Risk of Obesity in Han Chinese Male Children

A genome-wide association study (GWAS) in the Han Chinese population had found that single nucleotide polymorphism (SNP) on the CMTM7 gene rs347134 was significantly associated with Body Mass Index (BMI). In the present study, the association of the rs347134 SNP with obesity and its interaction with dietary patterns (DPs) were explored in Han Chinese children. This cross-sectional study group included 1292 children, in whom obesity-related indicators were evaluated, the rs347134 SNP was genotyped by improved Multiple Ligase Detection Reaction (iMLDR), and the DPs were identified by principal component factor analysis. The GG genotype exhibited higher odds of general overweight/obesity (P = 0.038) and central obesity (P = 0.039) than AA + GA genotypes in boys. Four DPs of boys were identified: healthy balanced (HBDP), nuts and sweets-based (NSDP), animal food-based (AFDP), and wheaten and dairy-based (WDDP). Boys with the GG genotype were significantly more inclined to AFDP (P = 0.028) and had a shorter sleep duration (P = 0.031). Significant interactions were observed; boys with the GG genotype displayed a higher LDL in AFDP (P = 0.031) and higher FBG in NSDP (P = 0.038), respectively. Our findings indicate for the first time that the GG genotype of CMTM7 rs347134 is potentially a novel obesity risk factor for Han Chinese male children and is associated with dietary patterns more or less.

A cohort study assessing the sustainable long-term effectiveness of a childhood-obesity intervention in China

BACKGROUND

Obesity has become a global epidemic, with substantial impacts on children's health. Numerous intervention studies for the prevention of obesity in children have been conducted during the most recent decade, but very few have evaluated the long-term and sustainable effectiveness of such prevention efforts.

METHODS

We conducted a follow-up study during September 2015 and September 2017, based upon a previous 3-year cluster randomized-controlled study (RCT) for a comprehensive childhood-obesity intervention in 14 primary schools in Shanghai, China. A total of 929 students were enrolled in the study. Generalized estimating equation approaches were applied to analyse student's body mass index (BMI), BMI z-score at baseline and three annual long-term follow-ups.

RESULTS

Three years after the end of the RCT study, the odds of developing obesity and the odds of developing obesity or overweight in the intervention group were both lower than in the control group among girls [OR(obesity) = 0.299, p = 0.010 and OR (overweight/obesity) = 0.493, p = 0.013]; the odds of developing obesity or overweight in the intervention group was lower than in the control group among boys (OR = 0.369, p = 0.017). Compared with the baseline, the BMI z-scores in the intervention group were lower than those in the control group for both normal-weight students (-0.027) and overweight or obese students (-0.074).

CONCLUSIONS

The 3-year RCT showed significant and reliable long-term effects on preventing childhood obesity, particularly among girls.

Metabolic Syndrome and Related Factors in Chinese Children and Adolescents: Analysis from a Chinese National Study

Aims: Metabolic syndrome (MetS) has become a worldwide epidemic; however, few studies have described its status in Chinese children. This study aimed to estimate MetS status and its associations with geography, economic development, birth weight, and parental education of Chinese children and adolescents.

Methods: Data were derived from 15,045 participants aged 7–18 years across seven Chinese provinces. Physical measurement and blood tests were conducted to assess the five classical MetS components described by the International Diabetes Federation, including abdominal obesity (the essential component), high blood pressure, low high-density cholesterol (HDL-C), high triglyceride, and elevated fasting glucose (FG). Logistic regression was adopted to explore possible associations between MetS and other factors.

Results: Overall, MetS prevalence was 2.3%, higher in males (2.8% vs. 1.7% in females), northern regions (3.1%), more developed regions (2.9%), and older participants (aged 16–18 years) (P < 0.05 for all). Among the five MetS components, abdominal obesity and low HDL-C level were most prevalent (21.8% and 14.4%), and 35.9% of the participants had at least one component. In logistic regression, MetS itself did not correlate with birth weight or parental education. High birth weight was positively correlated with abdominal obesity (odds ratio, 1.48) butnegatively associated with elevated FG (odds ratio, 0.49).

Concusions: MetS itself was not common in Chinese children and adolescents, whereas its certain components were far more prevalent. Children from North China, more-developed areas, and at an older age were more likely to develop MetS. Strategies designed to prevent pediatric MetS in China should focus on prevalent components as well as its geographic and economic development predilections.

Prevalence of overweight and obesity among African primary school learners: a systematic review and meta-analysis

INTRODUCTION

The increasing trend in the global prevalence of childhood overweight and obesity presents a major public health challenge. This study reports the results of a systematic review and meta-analysis to estimate the prevalence of overweight and obesity among primary school learners residing in Africa according to the different body mass index criteria and population level characteristics.

METHODS

A search of multiple databases was conducted to identify relevant research articles published between January 1980 and February 2017. Random effects models were used to pool prevalence data within and across population level characteristics after variance stabilization through arcsine transformation (PROSPERO registration number CRD42016035248).

RESULTS

Data from 45 studies across 15 African countries, and comprising 92,379 and 89,468 participants for overweight and obesity estimates were included. Estimated overweight and obesity prevalence differed significantly across criteria: 10.5% [95% confidence interval, CI: 7.1-14.3] and 6.1% [3.4-9.7] by World Health Organization; 9.5% [6.5-13.0] and 4.0% [2.5-5.9] by International Obesity Task Force; and 11.5% [9.6-13.4] and 6.9% [5.0-9.0] by Centre for Diseases Control, respectively (p = 0.0027 for overweight; p < 0.0001 for obesity). Estimates were mostly higher in urban, and private schools, but generally similar by gender, major geographic regions, publication year and sample size. Substantial heterogeneity in the estimates across and within criteria were not always explained by major study characteristics.

CONCLUSION

Overweight and obesity are prevalent among African primary school learners, particularly those attending urban, and private schools. The results from this meta-analysis could be helpful in making informed decisions on childhood obesity prevention efforts in African countries.

Application Design for Child Obesity Management Based on Users' Preferences and Needs

This study aimed to investigate the constructive preferences and needs of children and guardians in a child obesity management application, and to suggest and visualize the key features of its design. To reflect users' preferences and needs, the questionnaires used in this study were developed in four stages: draft, validity test, review, and final version. The survey was conducted with fifth and sixth grade children who are overweight or obese and their guardians. Differences were observed by gender and between children and guardians with respect to children's perceived body shape, technology experience and preferences, preferred obesity management method, application design, exercise and diet-related features, preferred partner for obesity management, and preferred reward after mission completion. Our study suggests and visualizes the key features of a child obesity management application for both children and guardians based on their preferences and needs, which can be utilized by both application developers and researchers.

Association of Visual Impairment With Economic Development Among Chinese Schoolchildren

IMPORTANCE

Few studies have reported the association of economic growth with trends of visual impairment in schoolchildren in China or elsewhere.

OBJECTIVES

To describe 30-year trends and patterns in visual impairment in China and to explore the association between visual impairment and economic development.

DESIGN, SETTING, AND PARTICIPANTS

In this time series analysis of 7 successive cross-sectional surveys from 1985 to 2014, a total of 1 951 084 schoolchildren aged 7 to 18 years from all provinces and autonomous regions of mainland China, excluding Tibet, were studied. In 1985, the survey was conducted between March to June; In 1991-2014, the surveys were conducted between September and November. Data analysis was performed from April 1, 2018, to January 31, 2019.

EXPOSURES

The province-level gross domestic product (GDP) per capita was extracted from the China Statistical Yearbook.

MAIN OUTCOMES AND MEASURES

Visual impairment, defined as unaided distance visual acuity of worse than 6/7.5 (20/25 Snellen equivalent), and moderate to severe visual impairment, defined as unaided distance visual acuity of worse than 6/18 (20/63 Snellen equivalent), in the worse eye.

RESULTS

A total of 1 951 084 participants (mean [SD] age, 12.6 [3.4] years; 50.5% male) were included in the analysis. Among students aged 7 to 18 years, the prevalence of visual impairment increased from 23.7% (95% CI, 23.6%-23.8%) in 1985 to 35.1% (95% CI, 34.9%-35.3%) in 1995 to 55.0% (95% CI, 54.8%-55.3%) in 2014. In 2014, the prevalence was higher among girls (58.3%; 95% CI, 54.8%-55.3%) vs boys (51.8%; 95% CI, 51.5%-52.1%) (prevalence ratio [PR] girls vs boys, 1.12; 95% CI, 1.11-1.13) and among students living in urban (59.9%; 95% CI, 59.6%-60.2%) vs rural (50.2%; 95% CI, 49.9%-50.5%) areas (PR urban vs rural, 1.17; 95% CI, 1.16-1.18), although a more rapid relative increase in prevalence occurred in rural areas (15.3% in 1985 to 50.2% in 2014) than in urban areas (31.5% in 1985 to 59.9% in 2014). From 1995 to 2014, the GDP in China increased from $1263 to $7594 (in 2014 US$ constant price). After demographic characteristics (cluster effect of school, age, sex, urban vs rural location, and relative socioeconomic status within province) were adjusted for, the regression model revealed that every 100% increase in GDP was associated with a 20% (PR, 1.20; 95% CI, 1.20-1.21) increase in the relative risk of visual impairment and a 27% (PR, 1.27; 95% CI, 1.26-1.27) increase in the relative risk of moderate to severe visual impairment. The association was stronger in male (PR, 1.22; 95% CI, 1.21-1.23 for male [as reference] vs 1.19; 95% CI, 1.18-1.19 for female; P < .001), rural (PR, 1.32; 95% CI, 1.31-1.33 for rural [as reference] vs 1.12; 95% CI, 1.12,-1.33 for urban; P < .001), and younger age groups (PR, 1.27; 95% CI, 1.24-1.29 for 7-9 years of age [as reference] vs 1.34; 95% CI, 1.32-1.36 for 10-12 years of age; P < .001; 1.21; 95% CI, 1.20-1.22 for 13-15 years of age; P < .001; and 1.12; 95% CI, 1.11,-1.13 for 16-18 years of age; P < .001).

CONCLUSIONS AND RELEVANCE

The rapid increase of visual impairment prevalence and the association between GDP and visual impairment over time suggest that further exacerbation of childhood visual impairment may occur as economic development continues in China.

Decline of childhood overweight and obesity in Italy from 2008 to 2016: results from 5 rounds of the population-based surveillance system

Background

Given the effects of childhood obesity on future health, and the lack of information of its prevalence in Italy, a national surveillance system was implemented in 2007. It is OKkio alla SALUTE, part of the WHO/Europe Childhood Obesity Surveillance Initiative (COSI). This study reports the 2008–2016 trends by sex, area of residence and socio-demographic characteristics in the prevalence of overweight and obesity in primary school children (8–9 years).

Methods

In each round of the surveillance held in 2008, 2010, 2012, 2014 and 2016, a nationally representative sample of about 45,000 children, was weighed and measured with standard equipment and methods by trained personnel. Children were classified as normal weight, overweight or obese using World Obesity Federation (WOF) (formerly the International Obesity Task Force (IOTF)) and WHO cut-offs. Children’s sex, area of residence and mothers’ education and citizenship, were obtained using self-reported questionnaires and were assessed using multivariate logistic regression models.

Results

Between 2008 and 2016, the overall prevalence of obesity dropped from 12.0 to 9.3% (WOF-IOTF) and from 21.2 to 17.0% (WHO), while the overall prevalence of overweight (including obesity) from 35.2 to 30.6% (WOF-IOTF) and from 44.4 to 39.4% (WHO). Reduction in the prevalence of overweight and obesity was greater in boys (− 14.5%, p for trend< 0.001; and − 24.7%, p = 0.001) compared to girls (− 11.1%, p < 0.001; and − 19.2%, p = 0.034). Decreasing trends were observed in overweight prevalences within children resident in the center and in the south. Decreasing trends in obesity prevalences were observed among boys resident in the north and in the south, and among girls resident in the center. Decreasing trends were observed in overweight prevalences within socio–demographic characteristics, except among children with low educated and foreign mothers; and in obesity prevalences for children with medium educated mothers, and girls with Italian mothers.

Conclusions

From 2008 to 2016 a decrease of childhood overweight and obesity was observed in Italy. However, as these prevalences are still among the highest in Europe, there is need to continue their monitoring and implement more interventions to promote healthy lifestyles. More effort should be focused on children belonging to low social classes.

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.

Global patterns in excess body weight and the associated cancer burden

The prevalence of excess body weight and the associated cancer burden have been rising over the past several decades globally. Between 1975 and 2016, the prevalence of excess body weight in adults-defined as a body mass index (BMI) ≥ 25 kg/m² -increased from nearly 21% in men and 24% in women to approximately 40% in both sexes. Notably, the prevalence of obesity (BMI ≥ 30 kg/m² ) quadrupled in men, from 3% to 12%, and more than doubled in women, from 7% to 16%. This change, combined with population growth, resulted in a more than 6-fold increase in the number of obese adults, from 100 to 671 million. The largest absolute increase in obesity occurred among men and boys in high-income Western countries and among women and girls in Central Asia, the Middle East, and North Africa. The simultaneous rise in excess body weight in almost all countries is thought to be driven largely by changes in the global food system, which promotes energy-dense, nutrient-poor foods, alongside reduced opportunities for physical activity. In 2012, excess body weight accounted for approximately 3.9% of all cancers (544,300 cases) with proportion varying from less than 1% in low-income countries to 7% or 8% in some high-income Western countries and in Middle Eastern and Northern African countries. The attributable burden by sex was higher for women (368,500 cases) than for men (175,800 cases). Given the pandemic proportion of excess body weight in high-income countries and the increasing prevalence in low- and middle-income countries, the global cancer burden attributable to this condition is likely to increase in the future. There is emerging consensus on opportunities for obesity control through the multisectoral coordinated implementation of core policy actions to promote an environment conducive to a healthy diet and active living. The rapid increase in both the prevalence of excess body weight and the associated cancer burden highlights the need for a rejuvenated focus on identifying, implementing, and evaluating interventions to prevent and control excess body weight.

Prevalence of underweight and overweight among young adolescents aged 12-15 years in 58 low-income and middle-income countries

BACKGROUND

The co-existence of underweight and overweight is a great challenge for public health in low-income and middle-income countries (LMICs).

OBJECTIVES

The objective of the study is to report the prevalence of underweight, overweight and obesity among young adolescents in 58 LMICs.

METHODS

Data were from the Global School-based Student Health Survey (2007-2013) in 57 LMICs and from the Chinese National Surveys on Students' Constitution and Health (2010). A total of 177 325 young adolescents aged 12-15 years from 58 LMICs were included. Weight status was defined based on both the updated International Obesity Task Force (IOTF) and World Health Organization (WHO) criteria.

RESULTS

Based on the IOTF/WHO criteria, the overall prevalence of weight categories among young adolescents in LMICs was 13.4%/4.7% for underweight, 15.4%/17.3% for overweight and 5.6%/8.6% for obesity. However, the prevalence varied largely across countries and regions. Based on the IOTF criteria, the prevalence of underweight ranged from 0.0% in Niue to 48.8% in Sri Lanka and obesity ranged from 0.1% in Vanuatu to 35.0% in Niue; a prevalence exceeding 10.0% for both underweight and excess weight (overweight and obesity combined) was found in 29.3% of these countries. Underweight was more prevalent in Southeast Asia and Africa, while obesity was more frequent in Central and South Americas. There were no age and sex differences in the prevalence of weight categories for most countries.

CONCLUSIONS

Our data confirm the continued dual burden of underweight and overweight in young adolescents in many LMICs and the need for policy and programmes to address both conditions.

The Association of Grandparent Care with Childhood Overweight and Obesity in Chinese American Families

BACKGROUND

Grandparents are often the caretakers of children in Chinese American families. Studies have shown that Chinese grandparents underestimate the weight of their grandchildren and associate food with increased height and strength. This study examines the association of grandparental care with weight status in Chinese American children and adolescents.

METHODS

This is a cross-sectional study of 12,029 Chinese American pediatric patients ages 2-19 at a community health center in New York City in 2015. Grandparental care was defined as child care provided by at least one grandparent. Multivariable logistic regression was conducted to assess for association between having a grandparent caretaker and weight status in the age groups 2-5, 6-11, and 12-19 while adjusting for sex, place of birth, neighborhood poverty, and two-parent households.

RESULTS

Approximately 12% of Chinese American children in this population had a grandparent caretaker. Children and adolescents with grandparent caretakers are more likely to be overweight than their counterparts with no grandparent caretakers at ages 6-11 (odds ratio [OR]: 1.48; 95% confidence interval [CI]: 1.23-1.79) and ages 12-19 (OR: 1.54; 95% CI: 1.18-2.02). No association was found between grandparental care and overweight in ages 2-5 nor with obesity in any age group.

CONCLUSIONS

Grandparental care is associated with the weight of school-age children and adolescents. Targeted education on appropriate nutrition for the child's age is needed for grandparents who take care of children.

Prevalence of underweight, overweight and obesity among children and adolescents in Germany. KiGGS Wave 2 results according to international reference systems

In Germany, the reference system according to Kromeyer-Hauschild is usually used to define underweight, overweight and obesity in children and adolescents. International classification systems to describe prevalence are the reference systems of the World Health Organization (WHO) and the International Obesity Task Force (IOTF). This article reports underweight, overweight and obesity prevalences among children and adolescents according to WHO and IOTF criteria using data from the second wave of the German Health Interview and Examination Survey for Children and Adolescents (KiGGS Wave 2, 2014-2017). According to the WHO reference system, the prevalence of underweight among 5- to 17-year-olds is 1.6%, the prevalence of overweight is 26.3% (including obesity) and the prevalence of obesity is 8.8%. According to IOTF, the prevalence of underweight among 3- to 17-year-olds is 10.0%. The prevalence of overweight (including obesity) is 19.3% and the prevalence of obesity is 4.7%. From a public health point of view, underweight as an indicator of malnutrition plays a rather minor role in Germany. The prevalence of overweight according to WHO is three quarters higher and one quarter higher according to IOTF than the national reference. When comparing the international reference systems, the WHO prevalence is one third higher than IOTF prevalence. According to national and international reference systems, no further increase in the prevalence of overweight and obesity is observed, but the prevalence remain at a high level.

Genotype-by-sex-by-diet interactions for nutritional preference, dietary consumption, and lipid deposition in a field cricket

Changes in feeding behaviour, especially the overconsumption of calories, has led to a rise in the rates of obesity, diabetes, and other associated disorders in humans and a range of animals inhabiting human-influenced environments. However, understanding the relative contribution of genes, the nutritional environment, and their interaction to dietary intake and lipid deposition in the sexes still remains a major challenge. By combining nutritional geometry with quantitative genetics, we determined the effect of genes, the nutritional environment, and their interaction on the total nutritional preference (TP), total diet eaten (TE), and lipid mass (LM) of male and female black field crickets (Teleogryllus commodus) fed one of four diet pairs (DPs) differing in the ratio of protein to carbohydrate and total nutritional content. We found abundant additive genetic variance for TP, TE, and LM in both sexes and across all four DPs, with significant genetic correlations between TE and TP and between TP and LM in males. We also found significant genotype-by-DP and genotype-by-sex-by-DP interactions for each trait and significant genotype-by-sex interactions for TE and LM. Complex interactions between genes, sex, and the nutritional environment, therefore, play an important role in nutrient regulation and lipid deposition in T. commodus. This finding may also help explain the increasing rate of obesity and the maintenance of sex differences in obesity observed across many animal species, including humans.

Clustering of unhealthy lifestyle behaviours and associations with perceived and actual weight status among primary school children in China: A nationally representative cross-sectional study

Few studies have focused on clustering of unhealthy lifestyle behaviours among primary school children and potential associations with perceived and actual weight status. An index was constructed from adding up 13 unhealthy behaviours measured by survey responses. Multilevel linear regressions were used to analyse associations between child personal characteristics, perceived and actual weight status with the unhealthy lifestyle index among 11,157 children in primary schools across China. Parental and area factors were also taken into account, including education, weight status, physical activity, urban/rural and area socioeconomic circumstances. The unhealthy lifestyle index normally distributed, with 84.5% of children reporting between 2 and 6 unhealthy behaviours. Boys reported more unhealthy behaviours compared with girls (coefficient 0.32, 95%CI 0.26 to 0.37) and children in urban areas had fewer unhealthy behaviours than their rural counterparts (-0.29, 95%CI -0.56 to -0.03). An interaction revealed stronger 'protective' effects of living in cities for girls than boys, which were not explained by differences in child overweight/obesity. More unhealthy behaviours were characteristic of children in more affluent areas, and of those born to mothers and/or fathers with lower educational attainment. Children who perceived themselves as overweight or underweight both scored higher on the unhealthy lifestyle index. Unhealthy behaviours that could increase the risk of childhood obesity are common among Chinese primary school children, particularly among boys in cities, those in more affluent areas and with parents with lower education. There was no effect of actual weight status on number of unhealthy behaviours. Perceived, but not actual weight status, was also a significant correlate of unhealthy behaviours. Clustering of unhealthy lifestyle behaviours that could increase the risk of childhood obesity are common among Chinese primary school children, particularly among boys in cities, those in more affluent areas and with parents with lower education. Perceived, but not actual weight status, was also a significant correlate of unhealthy lifestyle. This has important implications for public health because understanding clustering of unhealthy lifestyle behaviours can be used to assist in the development of targeted obesity prevention initiatives.

20-year trends in prevalence of overweight and obesity among children aged 0-6 in Harbin, China: A multiple cross-sectional study

To examine the 20-year trends in the combined prevalence of overweight and obesity among children aged 0-6 years between 1995 and 2015 in Harbin, China, we selected altogether 49,553 children aged 0-6 years old by using a multistage stratified cluster sampling methods in Harbin, one provincial capital city in northeast China in 1995, 2005 and 2015. Height and weight information of the children were collected. We used the child growth standards of World Health Organization to calculate the Z-scores for body mass index (BMI). Cut-offs recommended by World Health Organization and International Obesity Task Force were used to define overweight and obesity for each children. We found there is no difference between boys' BMI and girls' among newborns in each survey point (p>0.05), but in older age groups, the BMI of boys was higher than that of girls (p<0.05). From 1995 to 2015, the average BMI was increasing continuously among boys older than 42 months and girls older than 48 months (p<0.01 for linear trend across year) in Harbin. The combined prevalence of overweight and obesity increased from 2.6% in 1995 to 7.6% in 2015. For every 10-year the risk of combined overweight and obesity in children aged 0-6 years increased by 167% (95%CI: 146%, 188%, p<0.01). The combined prevalence of overweight and obesity in most age subgroups showed an increasing trend over time (p<0.01 for trend test across survey year). The age when the combined prevalence of overweight and obesity dramatically increased was earlier in 2015 than that in 2005 and 1995. In conclusion, there was an increasing trend of the combined prevalence of overweight and obesity during the past 20 years in Harbin and the age when the prevalence dramatically increased became earlier. Comprehensive intervention should be undertaken among younger children to prevent and control children's overweight and obesity.

Improving Physical Fitness and Cognitive Functions in Middle School Students: Study Protocol for the Chinese Childhood Health, Activity and Motor Performance Study (Chinese CHAMPS)

Background: Sedentary lifestyles and their associated harmful consequences are public health concerns that impact more than half of the world’s youth population in both developed and developing countries. Methods: The Chinese Childhood Health; Activity and Motor Performance Study (Chinese CHAMPS) was a cluster randomized controlled trial to modify school physical activity policies and the physical education (PE) curriculum; using teacher training and parent engagement to increase opportunities and support students’ physical activity and healthy eating. Using a 2 × 2 factorial design, the study tested the incremental effects of increasing the amount and intensity of physical activity, alongside adding support for healthy eating, on health-related and cognitive function outcomes in Chinese middle school students. Results: The intervention was implemented by PE teachers in 12 middle schools in three Chinese cities, with a targeted enrollment of 650 students from August 2015–June 2016. The assessment of the outcomes involved a test battery of physical fitness and cognitive functioning at both baseline and at the end of the intervention. Process information on implementation was also collected. Discussion: The Chinese CHAMPS is a multi-level intervention that is designed to test the influences of policy and environmental modifications on the physical activity and eating behaviors of middle school students. It also addresses some key weaknesses in school-based physical activity interventions.

Prevalence and risk factors of elevated alanine aminotransferase among Korean adolescents: 2001-2014

BACKGROUND

An elevated alanine aminotransferase (ALT) level is a surrogate marker of non-alcoholic fatty liver disease (NAFLD), the most common liver disorder in adolescents. The majority of previous NAFLD studies in adolescents were performed in selected obese populations or had a cross-sectional design without a time-trend analysis. The purpose of this study was to estimate the prevalence and time trends of elevated ALT levels in a general adolescent population and to identify factors associated with ALT elevation.

METHODS

We analysed data of adolescent participants (aged 10-18 years) from the Korean National Health and Nutrition Examination Survey 2001-2014, a representative sample of the general population in South Korea. Suspected NAFLD was defined as ALT elevation (> 30 U/L) without hepatitis B surface antigen. In all statistical analyses, sampling weight- and design-based data were used.

RESULTS

ALT was elevated in 5.3% (standard error: 0.3%) of the study population of adolescent participants (N = 8455). No significant trends were found from 2001 to 2014 in the prevalence of elevated ALT among male and female adolescents. In multiple logistic regression analysis, elevated ALT was independently associated with sex (odds ratio [OR] male versus female 4.5; 95% CI, 3.3-6.2), obesity (OR 7.6; 95% CI, 5.3-11.0), and truncal obesity (OR 2.5; 95% CI, 1.8-3.5). Furthermore, male sex, obesity, truncal obesity and high household income level were associated with log-transformed ALT levels in multiple regression analysis.

CONCLUSIONS

In Korean adolescents of both genders, the prevalence of elevated ALT levels was stable from 2001 to 2014. This study has revealed that sex, obesity, truncal obesity and household income level are associated with ALT elevation in adolescents.

Prevalence and stabilizing trends in overweight and obesity among children and adolescents in China, 2011-2015

BACKGROUND

The prevalence of childhood overweight and obesity in developed countries appears to be plateauing. The purpose of this study was to provide the most recent data on the prevalence and trends in overweight and obesity among Chinese children and adolescents from 2011 to 2015.

METHODS

We used data collected in the China Health and Nutrition Survey (CHNS) and China Nutritional Transition Cohort Study (CNTCS). We used two waves of the survey in 12 provinces conducted in 2011 (aged 7-18 years; n = 1458) and 2015 (aged 7-18 years; n = 1084) to perform a trend analysis. We used data collected in 15 provinces (aged 7-18 years; n = 1617) to estimate the prevalence of overweight and obesity among Chinese children and adolescents in 2015.

RESULTS

In 2015, based on the Working Group for Obesity in China (WGOC) criteria, the prevalence of overweight and obesity were 14.0% (95% CI, 11.6-16.3) and 10.5% (95% CI, 8.4-12.6) in boys, and 9.7% (95% CI, 7.7-11.8) and 7.1% (95% CI, 5.2-8.9) in girls, respectively. The increase in BMI z-scores from 2011 to 2015 was statistically significant among adolescents (p = 0.0083), but not among children. No significant changes were observed in prevalence of overweight and obesity between 2011 and 2015, excepting adolescents aged 12-18 years (p = 0.0086).

CONCLUSIONS

Since 2011, overweight has remained stable, and obesity has stabilized in children, though not in adolescents. Although levels of childhood overweight and obesity in China are not high compared to other developed countries, they remain concerning enough that effective policies and interventions need to be sustained and intensified for lowering rates of childhood overweight and obesity.

Trends in Obesity, Overweight, and Thinness in Children in the Seychelles Between 1998 and 2016

OBJECTIVE

This study assessed trends in the prevalence of children and adolescents with obesity, overweight, and thinness in the Seychelles, a rapidly developing nation in the Indian Ocean, and changes in the distribution of BMI over time.

METHODS

Between 1998 and 2016, examination surveys were conducted every year in all students of four selected school grades (kindergarten, primary 4, secondary 1, and secondary 4) in all schools. We categorized BMI by using the International Obesity Task Force criteria.

RESULTS

Based on 70,187 observations, the prevalence of combined overweight or obesity increased largely and monotonically between 1998 and 2016, from 8.9% to 20.0% in boys and from 12.3% to 23.6% in girls, but the prevalence of underweight did not decrease. BMI increased mostly in the upper range of the BMI population distribution: percentile 5 (P5), -1.7%; P10, -0.8%; P25, 0.3%; P50, 2.5%; P75, 7.4%; P90, 12.7%; and P95, 13.3%.

CONCLUSIONS

The distribution of BMI was increasingly skewed, with a rising prevalence of obesity, a modest or null increase in BMI in a substantial proportion of the population, and a continued burden of underweight. Further studies should assess child growth trajectories and their underlying determinants, which may bear significance for weight control strategies.

Worldwide trends in body-mass index, underweight, overweight, and obesity from 1975 to 2016: a pooled analysis of 2416 population-based measurement studies in 128·9 million children, adolescents, and adults

BACKGROUND

Underweight, overweight, and obesity in childhood and adolescence are associated with adverse health consequences throughout the life-course. Our aim was to estimate worldwide trends in mean body-mass index (BMI) and a comprehensive set of BMI categories that cover underweight to obesity in children and adolescents, and to compare trends with those of adults.

METHODS

We pooled 2416 population-based studies with measurements of height and weight on 128·9 million participants aged 5 years and older, including 31·5 million aged 5-19 years. We used a Bayesian hierarchical model to estimate trends from 1975 to 2016 in 200 countries for mean BMI and for prevalence of BMI in the following categories for children and adolescents aged 5-19 years: more than 2 SD below the median of the WHO growth reference for children and adolescents (referred to as moderate and severe underweight hereafter), 2 SD to more than 1 SD below the median (mild underweight), 1 SD below the median to 1 SD above the median (healthy weight), more than 1 SD to 2 SD above the median (overweight but not obese), and more than 2 SD above the median (obesity).

FINDINGS

Regional change in age-standardised mean BMI in girls from 1975 to 2016 ranged from virtually no change (-0·01 kg/m2 per decade; 95% credible interval -0·42 to 0·39, posterior probability [PP] of the observed decrease being a true decrease=0·5098) in eastern Europe to an increase of 1·00 kg/m2 per decade (0·69-1·35, PP>0·9999) in central Latin America and an increase of 0·95 kg/m2 per decade (0·64-1·25, PP>0·9999) in Polynesia and Micronesia. The range for boys was from a non-significant increase of 0·09 kg/m2 per decade (-0·33 to 0·49, PP=0·6926) in eastern Europe to an increase of 0·77 kg/m2 per decade (0·50-1·06, PP>0·9999) in Polynesia and Micronesia. Trends in mean BMI have recently flattened in northwestern Europe and the high-income English-speaking and Asia-Pacific regions for both sexes, southwestern Europe for boys, and central and Andean Latin America for girls. By contrast, the rise in BMI has accelerated in east and south Asia for both sexes, and southeast Asia for boys. Global age-standardised prevalence of obesity increased from 0·7% (0·4-1·2) in 1975 to 5·6% (4·8-6·5) in 2016 in girls, and from 0·9% (0·5-1·3) in 1975 to 7·8% (6·7-9·1) in 2016 in boys; the prevalence of moderate and severe underweight decreased from 9·2% (6·0-12·9) in 1975 to 8·4% (6·8-10·1) in 2016 in girls and from 14·8% (10·4-19·5) in 1975 to 12·4% (10·3-14·5) in 2016 in boys. Prevalence of moderate and severe underweight was highest in India, at 22·7% (16·7-29·6) among girls and 30·7% (23·5-38·0) among boys. Prevalence of obesity was more than 30% in girls in Nauru, the Cook Islands, and Palau; and boys in the Cook Islands, Nauru, Palau, Niue, and American Samoa in 2016. Prevalence of obesity was about 20% or more in several countries in Polynesia and Micronesia, the Middle East and north Africa, the Caribbean, and the USA. In 2016, 75 (44-117) million girls and 117 (70-178) million boys worldwide were moderately or severely underweight. In the same year, 50 (24-89) million girls and 74 (39-125) million boys worldwide were obese.

INTERPRETATION

The rising trends in children's and adolescents' BMI have plateaued in many high-income countries, albeit at high levels, but have accelerated in parts of Asia, with trends no longer correlated with those of adults.

FUNDING

Wellcome Trust, AstraZeneca Young Health Programme.

Reference Equations for the Six-Minute Walk Distance in the Healthy Chinese Han Population, Aged 18-30 Years

Background

The six-minute walk test (6MWT) is a safe, simple, inexpensive tool for evaluating the functional exercise capacity. However, there is a lack of standard reference equations for the six-minute walk distance (6MWD) in the healthy Chinese Han population with an age of 18–30 years. The aims of the present study were as follows: 1) to measure the anthropometric data and the walking distance in a sample of healthy Chinese Han population, aged 18–30 years; 2) to construct reference equations for the 6MWD; 3) to compare the measured 6MWD of our cohort with previously published equations.

Methods

The anthropometric data, demographic, lung function and the walking distance of Chinese Han population, aged 18–30 years, were prospectively measured using a standardized protocol. Informed consent was obtained from each participant and the approval was obtained from the ethics committee of Wenzhou People’s Hospital. The 6MWT was performed twice and the longer 6MWD was used for further analysis.

Results

A total of 355 subjects (176 female and 179 male) completed the 6MWT, and the average walking distance was 627.3 ± 52.88 m. The walking distance was achieved by females compared with males (607.4 ± 51.00 m vs. 646.9 ± 47.15 m; p < 0.0001) and active subjects compared with non-active subjects (646.1 ± 48.27 m vs. 611.6 ± 51.52 m; p < 0.0001). Univariate analysis showed age, height, body mass index, resting blood pressure, heart rate and blood pressure after the walk test and difference in heart rate before and after the walk test were significantly correlated with the 6MWD. Stepwise multiple regression analysis showed that height and difference in heart rate before and after the walk test were independent predictors associated with the 6MWD. The reference equations from Caucasian, Canadian and Chilean populations tend to overestimate the walking distance in our subjects, while Brazilian and Arabian equations tend to underestimate the walking distance. There was no significant difference in the walking distance between Korean equations and the current study.

Conclusion

In summary, height and difference in heart rate before and after the walk test were the most significant predictors of the 6MWD, and the regression equations could explain approximately 38% and 31% of the distance variance in the female and male groups, respectively.