Report on Childhood Obesity in China （2） Verification of BMI Classification Reference for Overweight and Obesity in Chinese Children and Adolescents

Objective To verify Working Group for Obesity in China （WGOC） recommended body mass index （BMI） classification reference for overweight and obesity in Chinese children and adolescents using the data of 2002 China Nationwide Nutrition and Health Survey. Methods PediaWic metabolic syndrome （MetS） and abnormality of each risk factor for MetS were defined using the criteria for US adolescents. Definition of hyper-TC, LDL, and dyslipidemia in adults was applied as well. The average level and abnormality rate of the metabolic indicators were described by BMI percentiles and compared with general linear model analysis. Receiver operating characteristic analysis was used to summarize the potential of BMI to discriminate between the presence and absence of the abnormality of these indicators. Results There was neither significantly increasing nor significantly decreasing trend of biochemical parameter levels in low BMI percentile range （〈65th）. Slight increasing trend from the 75th and a significant increase were found when BMI≥85th percentile. In general, the prevalence of the examined risk factors varied slightly when BMI percentile〈75th, and substantial increases were consistently seen when BMI percentile≥75th. As an indicator of hyper-TG, hypertension and MetS, the sensitivity and specificity were equal at the point of BMI〈75th percentile, and the Youden＇s index of risk factors also reached peak point before 75th percentile except for MetS. When the BMI percentile was used as the screening indicator of MetS, Youden＇s index reached peak point at 85th percentile, just the point in the ROC graph that was nearest to the upper left comer. Conclusion The BMI classification reference for overweight and obesity recommended by WGOC is rational to predict and prevent health risks in Chinese children and adolescents. Lower screening cut-off points, such as 83th percentile or 80th percentile, should not be excluded when they are considered as overweight criteria in future intervention or prevention studies.     

Application of the WHO Growth Reference （2007） to Assess the Nutritional Status of Children in China

Objective To assess the nutrition status of children and adolescents in China using the WHO growth reference （2007） in comparison with that defined by the International Obesity Task Force （IOTF） and the Working Group on Obesity in China （WGOC）. Methods Overweight and obesity were defined by age-, sex-, specific BMI reference developed by WHO （2007）, IOTF （2000）, and WGOC （2004）, respectively. Stunting and thinness were defined as height and BMI less than two standard deviations （SD） of the WHO growth reference （2007）, respectively. Data of children and adolescents aged 5 to 19 years （n=54 857, 28 273 boys, 26 584 girls） from the 2002 China National Nutrition and Health Survey （CNNHS） were used in the study. Results The prevalence of overweight, obesity, stunting and thinness among Chinese children and adolescents aged 5-19 years was 5.0%, 1.2%, 13.8%, and 7.4%, respectively when the WHO growth reference （2007） was used, whereas the estimated absolute total number affected by these 4 conditions were 14.6, 3.7, 40.6, and 21.8 million, respectively. The prevalence of overweight and obesity was 18.1% in large cities, while the stunting prevalence was 25.1% in rural 4. Obesity prevalence assessed by the WHO growth reference was higher than that as assessed by the IOTF reference, and obesity prevalence assessed by the WGOC reference was lower than that as assessed by the IOTF reference. Conclusion The nutritional status of children and adolescents is not equal in different areas of China. Stunting is still the main health problem of the poor, while overweight and obesity are the main health problems in large cities.     

Report on Childhood Obesity in China （4） Prevalence and Trends of Overweight and Obesity in Chinese Urban School-age Children and Adolescents, 1985-2000

Objective To describe the nationwide prevalence of childhood overweight/obesity, and their group variations and trends over the past 20 years in the Chinese urban population. Methods Data sets of boys and girls at the age of 7-18 years collected from the series of Chinese national surveillance on students' constitution and health (CNSSCH) between 1985 and 2000 were divided into five socioeconomic and demographic groups, while BMI classification reference proposed by Working Group on Obesity in China (WGOC) was used as screening reference to calculate the prevalence and trends of overweight/obesity in these groups. Results In 2000, the prevalence of obesity and overweight in boys aged 7-18 years was 11.3% and 6.5% in Beijing, 13.2% and 4.9% in Shanghai, 9.9% and 4.5% in coastal big cities, and 5.8% and 2.0% in coastal medium/small-sized cities, respectively, while the prevalence of of obesity and overweight in girls of the same age group was 8.2% and 3.7% in Beijing, 7.3% and 2.6% in Shanghai, 5.9% and 2.8% in coastal big cities, and 4.8% and 1.7% in coastal medium/small-sized cities, respectively. The prevalence of obesity was low in most of the inland cities at an early stage of epidemic overweight. The epidemic manifested a gradient distribution in groups, which was closely related to socioeconomic status (SES) of the study population. However, a dramatic and steady increasing trend was witnessed among all sex-age subgroups in the five urban groups, and such a trend was stronger in boys than in girls, and much stronger in children than in adolescents. Conclusion Although China is at an early stage of epidemic obesity by and large, the prevalence of obesity in her urban population, particularly in coastal big cities has reached the average level of developed countries. The increasing trend has been rapid since early 1990s, and the increments in obesity and overweight are exceptionally high. The prospect of epidemic obesity in China is in no way optimistic. Therefore, preventive program should be focused on the improvement of the balance between caloric intake and energy expenditure, and interventions aimed at changing children's life styles.     

Disease risks of childhood obesity in China

Objective To estimate the relative risks of dyslipidemia, hypertension, diabetes mellitus, and metabolic syndromes among overweight and obese Chinese children compared with their normal weight counterparts. Methods Overweight and obesity were defined by age- and sex-specific BMI classification reference for Chinese children and adolescents. Pediatric metabolic syndrome （MetS） and each risk factor for MetS were defined using the criteria for US adolescents. Definition of hyper-TC, LDL, and dyslipidemia for adults was applied as well. General linear model factor analysis and chi-square test were used to compare the difference in metabolic indicators among normal weight, overweight, and obese groups. Multiple logistic regression analysis was performed to estimate the odds ratio of metabolic abnormalities between obesity, overweight, and normal weight children, after adjustment for living area, family economic level, age, sex, and daily exercise time and TV watching time, as well as different dietary indices in the model. Results Significant increases in blood lipids, glucose, and blood pressure were found among overweight and obese children as compared with their counterparts with normal weight. By applying WGOC-recommended BMI classification, the risks for hypertriglyceridemia, low HDL and dyslipidemia among overweight children were 1.9, 1.4, and 1.5 times, and was 3.3, 1.5, and 1.8 times among obese groups compared to their counterparts with normal weight after adjustment for age, sex, region, socioeconomic status, physical activity, and dietary intakes. The overweight and obese children （15-17.9 years） had a high-risk of developing hypertension, which was 2.3 and 2.9 times higher than their counterparts with normal weight. Above 90% obese adolescents had abdominal obesity, while less than 1% normal weight ones had abdominal obesity. No obese adolescents were free from any risk factors for MetS, while 36.9% of normal weight adolescents were from the risk factors. 83.3% obese boys and all obese girls had metabolic syndrome, while only 15.5% normal weight boys and 18.8% normal weight girls had metabolic syndrome. Four risk factors for metabolic syndrome were found in 8.3% obese boys while none in normal weight boys and girls. The prevalence of MetS among normal weight, overweight, and obesity groups was 1.5%, 18.3%, and 38.1% respectively. Conclusion The cardiovascular disease （CVD） risk factors are clustered in obese Chinese children. Our observations strongly suggest that efforts should be made to prevent the onset of overweight and its associated diseases during early childhood.     

The Influence of Secular Trends in Body Height and Weight on the Prevalence of Overweight and Obesity among Chinese Children and Adolescents

Objective To explore the influence of secular trends in body height and weight on the prevalence of overweight and obesity among Chinese children and adolescents. Methods The data were obtained from five cross-sectional Chinese National Surveys on Students’ Constitution and Health. Overweight/obesity was defined as BMI-for-age Z-score of per the Wold Health Organization (WHO) reference values. Body height and weight for each sex and age were standardized to those reported in 1985 (standardized height: SHY; standardized weight: SWY) and for each sex and year at age 7 (standardized height: SHA; standardized weight: SWA) using the Z-score method. Results The prevalence of overweight/obesity in Chinese children was 20.2% among boys and 10.7%among girls in 2010 and increased continuously from 1985 to 2010. Among boys and girls of normal weight, SHY and SHA were significantly greater than SWY and SWA, respectively (P < 0.001). Among boys and girls with overweight/obesity, SHY was significantly lower than SWY (P < 0.001), and showed an obvious decreasing trend after age 12. SHA was lower than SWA among overweight boys aged 7-8 years and girls aged 7-9 years. SHY/SHW and SHA/SWA among normal-weight groups were greater than among overweight and obese groups (P < 0.001). Conclusion The continuous increase in the prevalence of overweight/obesity among Chinese children may be related to a rapid increase in body weight before age 9 and lack of secular increase in body height after age 12.     

Ethnic Differences in Body Mass Index and Prevalence of Obesity in School Children of Urumqi City, Xinjiang, China

Objective To investigate the prevalence of obesity and distribution of body mass index （BMI） in school children of four ethnic groups in Urumqi, Xinjiang, China. Methods A total of 55 508 school children of Han, Hui, Uygur and Kazak nationalities aged 8-18 years were selected by a cluster sampling from a districts of Urumqi City for anthropometrie measurement and demographic survey. Prevalence of obesity and overweight and distribution of body mass index （BMI） by gender, age, and nationality were analyzed and compared. Cutoff points of BMI for defining obesity and overweight were based on the proposal set by the Working Group on Obesity in China （WGOC） to assess age-, gender- and nationality-specific prevalence of obesity and overweight. Results Prevalence of obesity was 5.34%, 6.78%, 3.39 %, and 1.22% for boys and 2.61%, 1.83%, 1.78%, and 1.40% for girls of Han, Hui, Uygur and Kazak nationalities, respectively. Prevalence of obesity tended to decrease with age overall, whereas that of overweight increased with age in Han children. Conclusions Prevalence of obesity in school children in Urumqi varies with their nationalities and is lower than that of an average national level and a level of western countries. Obesity is more prevalent in boys than in girls of Urmuqi overall, which is just the opposite in Kazak children. Han boys and Hui girls have the highest prevalence of obesity and Kazak boys and girls have the lowest ones. Prevalence of obesity decreases with age, but that of overweight shows a different trend.     

Dairy Consumption and Associations with Nutritional Status of Chinese Children and Adolescents

Objective This study aimed to describe frequency and quantity of total dairy consumption of Chinese children and adolescents and explore the associations between dairy consumption and nutrition status, including stunting, wasting, overweight, and obesity. Methods Participants included 28,250 children and adolescents aged 6-17 years old. A food frequency questionnaire(FFQ) including 100 kinds of food was used to collect information about frequency and quantity of dairy consumption. Determination of stunting was with a height cutoff value for age and gender, and determination for wasting, overweight, and obesity was with BMI for age and gender. Results Of the total sample, 36.1% of children aged 6-17 reported consuming dairy food more than once per day(≥ 1/day). The average total dairy intake of all the participants was 126.7 g/day. For boys, dairy consumption had an inverse correlation with stunting and wasting after controlling for confounders. For girls, dairy consumption was negatively associated with stunting and obesity after controlling for confounders as above. Conclusion Dairy consumption in Chinese children and adolescents was relatively lower than that in developed countries, and was negatively associated with stunting and wasting for boys and with stunting and obesity for girls.     

Empirical Changes in the Prevalence of Overweight and Obesity among Chinese Students from 1985 to 2010 and Corresponding Preventive Strategies

Objective To determine the extent of the obesity epidemic in school‐aged Chinese children in 2010 and track the increasing trend in different socioeconomic regions over the preceding 25 years. Strategies for preventing childhood obesity are suggested. Methods We used a dataset provided by the Chinese National Survey on Students’ Constitution and Health from 1985‐2010. Subjects were 7‐18‐year‐old students randomly selected from urban and rural areas in 30 provinces. Eight subgroups were created according to region and socioeconomic status. Results Increased rates of the epidemic (overweight and obesity combined) were greatest in large coastal cities‐32.6% and 19.1% among males and females, respectively. These rates has neared that of developed countries. Similar increases were found in all other regions, including the once poverty‐stricken rural west. The epidemic in most of the rural areas began after 2000, but has spread swiftly over the last decade. In 2010, it was estimated that 9.9% of Chinese school‐aged children and adolescents were overweight and that an additional 5.1% were obese, representing an estimated 30.43 million individuals. Conclusion The prognosis for China’s childhood‐obesity epidemic is dire. To prevent childhood obesity, we suggest several strategies, including reasonable dietary intake, increase physical activity, a change in sedentary lifestyles and corresponding behavioral modifications.     

广州市肥胖及超重儿童青少年代谢综合征患病情况调查

Objective To know prevalence of metabolic syndrome (MS) and metabolic abnormalities (MA) in overweight and obese children and adolescents in Guangzhou, China. Methods Totally, 439 children and adolescents aged six to 18 years were enrolled, including 129 obese, 115 overweight and 195 normal control ones. Their body height, body weight, waist circumference, hip circumference and blood pressure were measured, as well as their fasting blood glucose (FBG), lipid profiles and oral glucose tolerance test (OGTF). Results ①Prevalence of MS in overweight and obese children and adolescents was 20.9 % (27/129) and 10.4 % (12/115), respectively, 17.9 % (35/195) and 1.6% (4/244) in those with insulin resistance and non-insulin resistance, respectively. Prevalence of MS, each component of MA and cluster of each components of MA all increased in linear trend with their body mass index (BMI) or insulin resistance increasing. ② BMI correlated with all metabolic indicators and could independently predict risk of MS. Conclusions Prevalence of MS among overweight and obese children and adolescents in Guangzhou was considerably high, and BMI can be used as a suitable index for their obesity assessment in MS diagnosis.     

Association of Serum Folate and Vitamin B12 Concentrations with Obesity in Chinese Children and Adolescents

Objective This study aimed to evaluate the associations of serum folate and/or vitamin B₁₂ concentrations with obesity among Chinese children and adolescents.Methods A cross-sectional study was conducted including 3,079 Chinese children and adolescents,aged 6 to 17 years, from Jiangsu, China. Anthropometric indices, such as, children’s body mass index(BMI), BMI z-scores, waist circumference, and waist-to-height ratio were utilized. Multivariable linear regression and generalized addit...     

Report on childhood obesity in China (7). Comparison of NCHS and WGOC

OBJECTIVE: To test the validity of Working Group on Obesity in China (WGOC) reference in screening childhood obesity using obesity-related metabolic syndrome (MS) and its components as disease risk evidence. METHODS: A total of 2020 adolescents (1007 boys and 1013 girls) aged 14-16 years were sampled in Beijing, China. Anthropometric and biochemical measurements, as well as blood pressure parameters were available. Prevalence of overweight/obesity and related MS risk factors were analyzed across different body mass index (BMI) categories. The sensitivity and specificity of the WGOC cut-offs were compared with those of National Central Health Statistics (NCHS). RESULTS: Significantly high prevalence of MS and its components were found both in the obesity and overweight groups, which were classified by the WGOC and NCHS references. Similar distribution pattern of MS risk factors existed among different BMI categories, but the frequency and clustering of these factors in the obesity group classified by the NCHS were much higher. Owing to its irrelevant high cut-offs for overweight/obesity (especially for girls since the mid- adolescence), the NCHS reference had a high specificity but a low sensitivity. By contrast, the WGOC reference with a high sensitivity (90.1% for boys and 89.2% for girls) and a relative high specificity (96.4% and 92.8% for obese boys and girls, 78.1% and 68.9% for overweight boys and girls respectively) was more suitable to support the need for early screening, intervention, and treatment of childhood obesity in China. CONCLUSION: High sensitivity is more important than specificity in choosing appropriate screening tools for childhood obesity. Validity test demonstrates that it is rational to use the WGOC reference, established on the basis of the Chinese own reference population as a uniform screening tool for childhood obesity, which can effectively overcome the unnecessary treatment and psychosocial implications of stigmatization caused by misclassification.     

铜陵市7～13岁儿童体质指数的分布特征

目的研究铜陵市区7～13岁儿童体质指数的分布特征。方法采用整群抽样的方法,随机抽取铜陵市区内2所小学,普查所有7～13岁小学生共3076名的身高和体重,分析BMI的年龄别分布特点,并与中国学龄儿童BMI超重、肥胖标准进行比较。结果铜陵市区7～13岁儿童中男性BMI均高于女性,随着年龄增长BMI有逐渐升高的趋势;选取拟合后的BMIP85、P95曲线作为铜陵市区儿童超重、肥胖的筛查标准,并将这一标准与全国标准进行比较显示,男童和女童在7～13岁BMI的P85、P95值均低于全国标准。结论铜陵市儿童BMI分布特征与全国标准有一定的差异,可以使用新建立的BMI标准进行本地区7～13岁儿童超重、肥胖的筛查及诊断。     

广州市海珠区10～14岁小学生肥胖现状及影响因素分析

目的 了解小学生肥胖现状及影响因素。方法 在海珠区随机抽取3所小学,对1100名学生进行体格检查,并对调查对象发放有关肥胖影响因素的调查问卷。结果 本次调查肥胖检出率为5．82％,其中男生533人,肥胖检出率为6．57％;女生567人,肥胖检出率为5．11％,男女间肥胖检出率差异无统计学意义;各年龄组肥胖检出率差异有统计学意义,其中11岁组的肥胖检出率最高;对相关影响因素进行logistic回归分析,进食速度OR=1．615,家长肥胖OR=1．808。结论 不良的生活方式与肥胖的发生密切相关,进食速度、家长肥胖是肥胖的危险因素。     

上海地区儿童超重和肥胖的评价标准比较

目的比较和分析四种基于身高、体质量的儿童肥胖的评价标准。方法选取上海市2347名7～8岁的儿童,其中男生1175名,女生1172名,测量其身高、体质量,并计算体质量指数。分别采用身高别体质量法（1985）标准（WFH1985标准）、中国肥胖问题工作组儿童青少年体质指数标准（WGOC标准）、欧洲国际肥胖工作组儿童青少年体质指数标准（IOTF标准）与美国疾病预防控制中心儿童青少年体质指数标准（CDC标准）评价儿童超重和肥胖的发生率。结果①男生超重发生率为IOTF标准明显高于其他三个标准（P〈0．05）,女生超重发生率IOTF标准明显高于WGOC标准和CDC标准（P〈0．05）;男生肥胖发生率IOTF标准明显低于其他三个标准（P〈0．01）;女生肥胖发生率IOTF标准明显低于WFH1985标准和WGOC标准（P〈0．01）。②WFH1985标准和WGOC标准对肥胖和超重的评价结果差异无统计学意义（P〉0．05）。结论WFH1985标准和WGOC标准比IOTF和CDC标准更适合我国儿童超重和肥胖发生率的筛查。     

Epidemics of overweight and obesity among growing childhood in China between 1997 and 2009: Impact of Family Income,Dietary Intake,and Physical Activity Dynamics

Background:Obesity has become a major health problem among children and adolescents worldwide.This study aimed to examine the trends of overweight and obesity among childhood in China and assess their ...     

Prevalence of overweight/obesity in Chinese children

BACKGROUND: The purpose of this paper was to report the prevalence of overweight/obesity by area, age, and gender in the year 2000 and to explore at what age adiposity rebound as measured by BMI occurs for Chinese children. METHODS: A cross-sectional study was carried out among 262,738 children aged 3.5-6.4 years in 26 counties/cities in China. Weight and height were measured from March 2000 through July 2000 by local trained health workers. International age- and gender-specific BMI cut-off points were used to obtain comparable prevalence rates of overweight/obesity. Multiple logistic regression was used to estimate odds ratios (OR) of being overweight/obesity for different comparisons. RESULTS: There were 19,390 overweight (16,738) or obese (2,652) children, resulting in an overall prevalence rate of 7.4% (95% CI: 7.3-7.5%). Girls were more likely to be overweight or obese than boys (OR = 1.14, 95% CI: 1.11-1.17). Compared with children living in the southern urban area, multivariate ORs for those living in northern rural and southern rural areas were 2.58 and 1.15, respectively. Compared with children aged 6.0-6.4 years old, multivariate ORs for children aged 3.5, 4.0, 4.5, 5.0 and 5.5 years were 1.96, 1.88, 1.56, 1.53, and 1.11, respectively (p<0.001). CONCLUSIONS: Childhood overweight/obesity in Chinese children in 2000 is similar to the conditions of Great Britain or the U.S. in the 1980s or earlier. Age at adiposity rebound as measured by BMI for Chinese children is >6.5 years old.     

Obesity and metabolic risks in children

BACKGROUND: We undertook this study to establish the prevalence of overweight, obesity, abdominal obesity, high blood pressure, and high glucose and triglyceride levels in school-age children from Mexico City, as well as to determine how overweight and obesity are related to the other risk factors. METHODS: The study was a cross-sectional survey comprised of 1819 children (6-13 years of age) attending six elementary schools. Gender, age, weight, height, waist circumference, blood pressure, and levels of triglycerides and glucose were registered. Percentiles were calculated according to American standards for BMI, height, waist circumference, and blood pressure. RESULTS: Compared to American references, mean percentiles for waist circumference and BMI were >50, and mean height percentiles were <50. Prevalence of overweight was 22.3 and 23.6% for boys and girls, respectively; obesity, 28 and 21.2%; abdominal obesity, 22.1 and 11.7%; high triglyceride levels, 11.3 and 15.4%; high blood pressure, 4.8 and 5.8%, respectively. Overweight, obesity, and abdominal obesity are associated with higher blood pressure and triglyceride levels (odds ratio>1.0, p<0.05). Percentiles for BMI, waist circumference, systolic blood pressure, and diastolic blood pressure also had significant correlations (r>0.2, p<0.001). CONCLUSIONS: This population of Mexican school-age children was shorter and heavier than their American standards. The prevalence of metabolic risks was similar to those reported in American adolescents in NHANES surveys.     

足月母乳喂养学龄前儿童超重肥胖与出生体重关系的性别差异

目的 探讨足月母乳喂养学龄前4 岁~5 岁儿童超重肥胖与出生体重之间的关系有无性别差异,为预防和减少儿童单纯性肥胖提供科学依据.方法 随机抽取扬泰地区60 所幼儿园4 000 名4 岁~5 岁足月母乳喂养学龄前儿童,采用1∶1 匹配的病例对照研究方法,对筛查出的645 名超重肥胖儿童和匹配的645 名正常体重儿童进行现场问卷调查,分析其出生体重与儿童肥胖关系有无性别差异.结果 无论是男童（OR=3.289,P=0.000） 还是女童（OR=2.622,P=0.000）,高出生体重是学龄前儿童肥胖发生的危险因素.对于男童（OR=3.229,P=0.002）而言,低出生体重是学龄前儿童超重、肥胖的危险因素;对于女童（OR=2.011,P=0.094）而言则不然.曲线拟合分析结果表明,男童BMI与出生体重之间呈现＂U＂形分布（P〈0.05）,女童BMI与出生体重之间呈现＂半U＂形分布（P〈0.05）.结论 出生体重与学龄前儿童超重肥胖之间的关系存在性别差异,在儿童肥胖的干预和预防工作中需要考虑到性别差异.