[The trend analysis of overweight and obesity in Chinese students during 1985 - 2010].

OBJECTIVE: To analyze the trend of overweight and obesity in students in China during 1985 - 2010. METHODS: The data were from Chinese National Survey on Students Constitution and Health in 1985, 1995, 2000, 2005 and 2010, and the sample sizes were 204 977, 216 786, 234 421, 215 319, respectively. BMI was calculated with height and weight. The prevalence of overweight and obesity as well as the rates of increase were described based on the BMI percentile criteria of Working Group on Obesity in China (WGOC). RESULTS: In 2010, the prevalence of overweight and obesity in four groups students (urban boys, urban girls, rural boys, and rural girls aged 7 - 18 years) were 23.23% (12 503/53 830), 13.76% (7 414/53 857), 12.72% (6 839/53 744), 8.56% (4 612/53 888), respectively, which were higher in boys and urban, and reached the peak 17.14% (18 463/107 741) in students aged 7 - 12 years. The prevalences of obesity were 0.44% (8/1800) - 21.67% (390/1800) among children aged 7 - 18 years in different provinces. The prevalence of overweight and obesity during 1985 - 1995, 1995 - 2000, 2000 - 2005 and 2005 - 2010 increased 0.10%, 0.30%, 0.23%, 0.23%, respectively, and the increase rate was higher in urban than in rural during 1985 - 2005. During 1985 - 1995, the increase rate of obesity in four groups students were 0.20%, 0.13%, 0.05% and 0.03%, respectively. During 2005 - 2010, the increase rates of obesity in four groups of students were 0.30%, 0.10%, 0.34%, 0.17%, respectively, and the increase rate was higher in rural than in urban. CONCLUSION: The prevalence of obesity among 7 - 18 years-old children increased rapidly during the 1985-2000, and the increase rate of obesity in rural exceeded that in urban during 2005 - 2010.

[Study on growth of height among students during their adolescence in Zhongshan, Guangdong].

OBJECTIVE: To discuss characteristics of height growth such as Peak Height Velocity (PHV) and Age at Peak Height Velocity (PHA) during adolescence, and to compare the results with other research findings. METHODS: Primary and middle school students' annual physical examination data of Zhongshan in 2005 - 2010 was used. The height velocity by age, PHV, PHA, height velocity by PHA were calculated. RESULTS: The average peak height velocity boys was (10.03 ± 1.67) cm/yr. and that of the girls was (8.39 ± 1.05) cm/yr. Both findings were close to the results from previous similar findings. The average age at which peak height velocity reached 12.28 ± 1.30 years for boys and 10.78 ± 1.04 years for girls, both lower than the previous findings. The correlation coefficients, between height level and PHA were -0.357 (P < 0.001) for boys and -0.338 (P < 0.001) for girls. CONCLUSION: The height levels were positively related to the height velocity before PHA. The Zhongshan students' PHA was lower than the Beijing, Shanghai and Shenyang students, also lower than American and Britain students', but their PHVs were similar.

[Study on the references regarding height and prevalence of stunting among children and adolescents aged 7 to 18 years of Chinese Han ethnicity].

OBJECTIVE: To develop the reference on height among children and adolescents aged 7 to 18 years of Chinese Han ethnicity in different administrative districts of China and to use this height reference for screening stunting. Results from the national screening program were compared with the WHO references. METHODS: Data from the Chinese National Survey on Students Constitution and Health in 2005 was used to develop the height references through LMS method. RESULTS: Differences among the references on height for children and adolescents in different districts (I-IV) were remarkable. The highest was seen in the Second Districts while the lowest was seen in the First Districts among those at the age of 18, with differences as 3.18 cm for boys and 2.92 cm for girls. The heights from the inland were shorter than that of the WHO references, with the differences ranging from 0.31 cm to 5.07 cm for boys, and from 0.98 cm to 4.22 cm for girls. The prevalence rates of stunting were 2.22%, 2.29%, 5.25%, respectively according to local references, national references and the WHO references. CONCLUSION: Universal height references from the whole nation could not discriminate the variations caused by geographic conditions and hereditary factors related to socio-economic situations. Height references should be developed locally, to evaluate height levels of the areas.

[Effects of overweight and obesity on physical function among children and adolescents: a multilevel analysis].

OBJECTIVE: To analyze the influence of overweight and obesity on body function among children and adolescents using a multilevel model, and to provide the basis for understanding their influence. METHODS: According to the "Reference Norms for Screening Overweight and Obesity in Chinese Children and Adolescents" set up by Working Group Obesity in China (WGOC) in 2003, we screened out individuals with overweight and obesity from the data obtained from the body and health survey of Chinese children and adolescents in 2005. The samples of the non-overweight group and the overweight group were randomly selected from the screened data by 1:1 match with samples of the obesity group by gender and city/rural area, then underwent the multilevel model to explore the influence of overweight and obesity on body function. RESULTS: The single dependent variable model showed that the overweight group had significant increases in systolic blood pressure (SBP) and diastolic blood pressure (DBP) by 5.25 mmHg (1 mmHg=0.133 kPa) and 3.44 mmHg, respectively (P<0.01), when compared with the non-overweight group. There were no significant differences between the overweight and non-overweight groups in pulse and vital capacity (VC) (P>0.05), and the obesity group had significant increases in SBP, DBP, pulse and VC by 10.15 mmHg, 6.34 mmHg, 1.44 times/min and 390.04 mL, respectively (P<0.01), when compared with the non-overweight group. The multiple dependent variables model showed that the SBP, DBP and pulse of the overweight group and obesity group were significantly greater than those of non-overweight group (P<0.01). There was a significant difference between the overweight group and non-overweight group in VC (P<0.05), yet the same result was not found between the obesity group and non-overweight group (P>0.05). CONCLUSION: Overweight and obesity may cause a decline in body function among children and adolescents, and obesity has a more obvious influence on body function.

[District differences and regional division of heights among Chinese Han children and adolescents].

OBJECTIVE: To analyze the district differences of height among Chinese Han population aged 7 to 18 years, and to divide the levels of heights into several regions accordingly, to provide basis for evaluation the development of height in the above said population. METHODS: Standard Deviation was used to compare the relative levels of height in different provinces and to divide them into several regions. The results were then showed in map through the Geographic Information System (GIS). RESULTS: All the 30 provinces in China were divided into three regions: high, medium and short regions according to the stature. Region with high stature was mainly located in northern, while medium stature was in central and northwest parts and short stature was in southwest parts of China. The differences of height appeared to be significant among regions in every age group. The differences of height were 1 - 3 cm between adjacent regions, and were even lager between the regions with high or short stature which appeared to be 4 - 5 cm. CONCLUSION: Overall, heights among the Chinese Han children and adolescents were taller in the northern and shorter in the southern areas. The highest and lowest levels of heights were in the Northern and the Southwest areas respectively. It was observed that the levels of height in the coastal areas were higher than that of the inland. There were no absolute boundaries between different regions because of the gradual transition in the levels of heights in various districts.