Ethnic and gender differences in body fat in British schoolchildren as measured by DXA

Background

There are known to be ethnic differences in body composition in adults which are related to ethnic differences in adult disease.

Objectives

To evaluate gender and ethnic differences in percentage body fat in British schoolchildren and to compare these differences with classification of obesity using body mass index (BMI) criteria.

Design

A cross‐sectional study of 1251 healthy children and adolescents aged 5–18 years from white, South Asian and African‐Caribbean ethnic groups. Percentage body fat was determined by dual x ray absorptiometry and the subjects classified using BMI criteria for overweight and obesity.

Results

Significant gender differences in percentage body fat were seen, with girls having higher values from the age of 5 years. Girls had 3.8% higher percentage body fat at 5 years of age increasing to 12.9% at 18 years of age. Significant ethnic differences were found, with South Asian girls and boys having the highest percentage body fat from 5 and 7 years of age, respectively. These differences increased with age, being most significant in the teenage years. Although South Asian girls and boys were over‐represented in the group containing children with more than 25% body fat (p<0.0001, χ² test), African‐Caribbean subjects were more likely to be classified as obese using BMI criteria.

Conclusions

There are clear gender and ethnic differences in percentage body fat in British schoolchildren which may relate to known differences in the risk of type 2 diabetes in adolescence and adulthood. BMI criteria for defining overweight and obesity do not accurately identify ethnic differences in body fat.     

儿童青少年体位性心动过速综合征体质量指数变化

目的　目的 探讨儿童青少年体位性心动过速综合征（POTS）体质量指数（BMI）的变化。方法　回顾性分析2009年8月至2018年6月因不明原因晕厥或晕厥先兆在中南大学湘雅二医院儿童晕厥专科门诊就诊、并诊断为POTS的4～17岁儿童青少年的临床资料。POTS组127例,男63例,女64例,平均年龄（11.31±2.53）岁。将同期在该院儿童保健专科门诊进行健康检查的127例7～17岁儿童青少年作为对照组,男64例,女63例,平均年龄（11.60±3.27）岁。测量两组儿童身长、 体质量,计算BMI。采用SPSS 22.0软件进行数据统计分析。结果　（1）病程和晕厥频次：POTS组病程为（8.13±13.76）个月,晕厥频次为（1.45±4.43）次。（2）BMI组间比较： POTS组与对照组比较, 年龄、 身长、 体质量差异无统计学意义（P＞0.05）, BMI明显降低［（17.32±2.65） kg/m2 vs.（18.17±2.42 ）kg/m2, t＝2.655, P＜0.01］。（3）BMI分类： 体质量过低在POTS组（69.29%, 88/127）高于对照组（56.69%,72/127）, 体质量正常在POTS组（29.13%, 37/127）低于对照组（41.73%, 53/127）, 组间比较χ2 ＝4.444, P＜0.05。结论　儿童青少年POTS组BMI明显降低, 且女性低于男性。     

Bodyfat percentage in girls increased steadily with age and percentile rank of body mass index

BACKGROUND: The purpose of the present study was to determine the body composition of elementary school children by bioelectrical impedance analysis (BIA) method with a subject in a standing position. The method is frequently used in Japan. The other aim was to evaluate the relationship between the body composition and percentile rank of the body mass index (BMI) in Japanese children. METHODS: The number of subjects were 1042 children (530 boys and 512 girls aged from 6- to 12-years-old) from an elementary school. The bioelectrical impedance (BI) in the standing position was measured late in the morning before lunch. The fat percentage was derived from the body density according to the formula of Brozek et al. Each percentile value of BMI for each age and sex was determined from the frequency table of height and weight published by the Ministry of Education in Japan. RESULTS: The fat percentage in both boys and girls was significantly correlated with the BMI, however, girls showed a closer linear relation than boys. The fat percentage in girls increased steadily with age and percent rank of the BMI. The fat percentage in boys was scattered in a wide range at each percentile rank of the BMI. CONCLUSIONS: The fat percentage measured by the BIA in the standing position is closely associated with the percentile rank of the BMI in elementary school girls. For boys, it will be necessary to compare data among different types of BI measurement methods.     

Body image and depressive symptoms in 13‐year‐old adolescents

Aims: To evaluate the prevalence of body dissatisfaction and the association with depressive symptoms in 13‐year‐old adolescents, according to gender, and also to analyse the possible modifying effect of body mass index on this association. Methods: We evaluated 1868 adolescents as part of a population‐based study in an urban community in Porto, Portugal. Using the Figure Rating Scale, participants choose their perceived and their desired figures; body dissatisfaction was measured by the difference between these values. The Beck Disorder Inventory II was used to measure depressive symptoms. Weight and height were measured by trained interviewers. To quantify the association between depressive symptoms and body dissatisfaction, regression parameters and 95% confidence intervals (CIs) were obtained by linear regression and bootstrapping. Results: Among females, 15.8% desired a bigger figure and 41.4% desired a thinner figure. Among males, this occurred for 34.1% and 33.5%, respectively. After adjustment, we found that body dissatisfaction was associated with increased depressive symptoms, in both genders, especially in those participants who wish to be thinner and in those presenting higher discrepancy between figures (B = 6.5, 95% CI 4.1;9.3 for females, B = 3.3, 95% CI 1.3;6.8 for males). The association between body dissatisfaction and depressive symptoms was stronger among non‐overweight (for participants who wish to be thinner: B = 5.18 95% CI 3.56; 6.95 vs. B = 3.49, 95% CI 1.70; 5.29 among females and B = 2.47, 95% CI 0.73; 4.76 vs. B = 1.60, 95% CI 0.34; 2.88 among males). Conclusions: The direct association between the wish to be thinner and depressive symptoms was stronger among the non‐overweight youth.     

Percent body fat,skinfold thickness or body mass index for defining obesity or overweight,as a risk factor for asthma in schoolchildren: which one to use in epidemiological studies?

None of the epidemiological studies indicating that obesity is a risk factor for asthma in schoolchildren have used the percent body fat (PBF) to define obesity. The present study compares the definition of obesity using body mass index (BMI), PBF and the raw sum of the thickness of four skinfolds (SFT) to evaluate this condition as a risk factor for asthma. All classes of children of the target ages of 6-8 years of all schools in four municipalities of Murcia (Spain) were surveyed. Participation rate was 70.2% and the number of children included in the study was 931. Height, weight and SFT (biceps, triceps, subscapular and suprailiac) were measured according to standard procedures. Current active asthma was defined from several questions of the International Study of Asthma and Allergies in Childhood questionnaire. Obesity was defined using two standard cut-off points for BMI and PBF, and the 85th percentile for BMI, PBF and SFT. The highest quartile of each type of measurement was also compared with the lowest. A multiple logistic regression analysis was made for the various obesity definitions, adjusting for age, asthma in the mother and father and gender. The adjusted odds ratios of having asthma among obese children were different for boys and girls and varied across the different obesity definitions. For the standard cut-off points of BMI they were 1.19 [95% confidence interval (CI) 0.41-3.43] for girls and 2.00 (95% CI 0.97-4.10) for boys; however, for PBF (boys 25%, girls 30%) the corresponding figures were 1.54 (95% CI 0.63-3.73) and 1.20 (95% CI 0.66-2.21). BMI, PBF and SFT showed more consistency between each other when using the other cut-off points. BMI, PBF (except standard cut-off points) and SFT produce relatively comparable results when analysing the interaction between obesity and asthma.     

Large summer weight gain in relatively overweight preschool Japanese children

Background: Children's lifestyles have changed recently in Japan. These changes are thought to be associated with their physical growth. The aim of the present paper was to describe and interpret the growth seasonality of children attending day‐nurseries in Osaka Prefecture, Japan. Methods: Results were based on a 6 year follow‐up study of preschool children aged 0 at baseline to 6 years old at the end of the follow up. Longitudinal growth data for 148 boys and 113 girls, born between April 1990 and March 1991, attending day‐nursery were obtained monthly from April 1990 through to March 1996. Children were divided into two groups: those with a normal (<17) or high (≥17) body mass index (BMI) at 5 years of age. Weight and height seasonal gains were estimated for each group. Results: Weight gain was higher during autumn among the group with a normal BMI at 5 years of age. Among high BMI group, weight gain was higher during autumn when they were 0 to 4 years of age, while it was higher during summer when they were 5 years of age. Height gain was higher in spring and summer in both BMI groups. Results were similar in boys and girls. Conclusion: Although the findings are consistent with previous studies for normal BMI children, the present study reports new findings for children with a high BMI at 5 years of age, for whom a large weight gain occurred during summer.     

贵阳市7～17岁少年儿童体质指数分布及超重肥胖状况

目的 了解贵阳市少年儿童体质指数分布及超重、肥胖状况,为儿童营养健康教育提供依据.方法 采用整群随机抽样的方法抽取贵阳市7所中、小学7～17岁的8 616名学生为研究对象,测量身高、体重,计算出体质指数百分位数值.以国际生命科学会中国肥胖问题工作组(WGOC)颁布的"中国学龄儿童青少年超重、肥胖筛查体质量指数值分类标准",对贵阳市少年儿童超重、肥胖状况进行筛查.结果 与WGOC采用的以体质指数P85和P95作为超重和肥胖筛查标准相比,贵阳市男孩P85、P95值均有相对增高趋势,而女孩P85、P95值变化相对不明显;贵阳市少年儿童超重和肥胖总检出率为12.5%和6.8%,其中男孩分别为15.0%和8.4%,女孩分别为9.9%和5.2%,男孩超重、肥胖检出率均高于女孩(P均<0.01).结论 贵阳市超重肥胖儿童日益增多,应重视对儿童超重、肥胖的预防工作.     

Recommended body mass index cutoff values for overweight screening programmes in Australian children and adolescents: Comparisons with North American values

Objectives: Guidelines for screening children and adolescents for overweight have recently been published by a North American Expert Committee. As Australian clinicians might uncritically adopt these recommendations, we explore the consequences of applying North American body mass index (BMI) cutoff values to an Australian population. Methodology The Australian BMI cutoffs were calculated using the methods recommended from height and weight data for 8492 schoolchildren aged 7-15 years old. Results Smoothed Australian BMI cutoffs were similar to those derived from the first United States National Health and Nutrition Examination Survey (NHANES-I) values for whites. However, the NHANES-I cutoffs would result in systematic misclassification. Among 7 year olds, the NHANES-I 85th percentile cutoff would wrongly classify 4.6% of normal males and 9.1% of normal females as ‘at risk of overweight’. At age 14 years, the NHANES-I 95th percentile cutoff would misclassify 3.5% of children as ‘overweight’ instead of ‘at risk of overweight’. Conclusion Australian screening programmes should use BMI cutoffs appropriately derived from local measurements, and these are given for Australian children.     

Does maternal obesity adversely affect breastfeeding initiation and duration?

OBJECTIVE: To examine the relationship between maternal obesity and the initiation and duration of breastfeeding. METHODS: Analysis was made of the 1995 National Health Survey, in which personal interviews were conducted on a multistage area sample of private dwellings and a list sample of non-private dwellings in all states and territories of Australia. Mothers between the ages of 17 and 50 years (n = 1991) with children under the age of 4 years in 1995 participated in the study. RESULTS: Of the group of mothers with a body mass index (BMI) of 20-25, 89.2% (95% confidence interval (CI) 87.4-91.0) initiated breastfeeding, compared with 82.3% (95% CI 77.6-87.0) of mothers with a BMI of 30 or more. There was also a significant difference between the mean and median duration of breastfeeding of obese and non-obese mothers (BMI 30 and over, < 25, respectively). These differences remained significant when maternal smoking, age and other sociodemographic factors were taken into consideration. CONCLUSIONS: Health professionals should be aware that obese women may be at increased risk of not breastfeeding or stopping breastfeeding prematurely.     

Does lean rather than fat mass provide the link between birth weight,BMI, and metabolic risk? EarlyBird 23

BACKGROUND: High birth weight predicts subsequent obesity, but paradoxically, a reduced risk of subsequent cardiovascular disease compared with low birth weight. This apparent paradox might be explained if high birth weight programmed a greater proportion of subsequent lean mass, which carries less cardiovascular risk than fat tissue. AIM: The aim of this study was to test the hypothesis that the direct correlation between birth weight and subsequent body mass index (BMI) represents an association between birth weight and lean tissue, and to assess the metabolic impact of this relationship. METHODS: A total of 234 healthy prepubertal children (133 boys, 101 girls, mean age 5.9 yr +/- 0.3 standard deviation) were studied. Birth weights were obtained from maternity records. Lean mass was measured by bioelectrical impedance. Anthropometric measures included height, weight (BMI), waist circumference, and subcutaneous fat mass (FM). Insulin resistance was assessed by the homeostasis model method. Metabolic correlates of insulin resistance included total and high-density lipoprotein cholesterol, triglycerides, and sex-hormone-binding globulin. RESULTS: Birth weight correlated significantly with lean mass in boys (r = 0.41, p < 0.001) and girls (r = 0.27, p < 0.01). Adjusting for BMI did not improve the correlation further. After adjustment for FM, lean mass correlated inversely with triglycerides in boys only (r = -0.41, p < 0.01). Birth weight correlated inversely with triglycerides in boys (r = -0.18, p < 0.05); after adjustment for lean mass, this correlation was not significant. INTERPRETATION: In boys, the relationships between birth weight, triglycerides, and lean mass are consistent with the hypothesis. Overall, our findings provide limited evidence in support of the argument that higher birth weight predicts lower metabolic risk because it marks programming of more lean mass.     

Body composition measured by dual-energy X-ray absorptiometry half-body scans in obese children

Aim: To perform a methods comparison of a left or right half‐body scan versus whole‐body scan for measuring body composition in a sample of obese children. Methods: A group of obese children (n = 58; ≥95th BMI percentile; 8–18 years) were required to undergo a dual‐energy X‐ray absorptiometry (DXA) body composition measurement as part of an ongoing cohort study; 34 fit within the imaging field of the DXA scanner and were eligible for inclusion in the present analysis. Percent fat, total mass, fat mass, lean mass and bone mineral content (BMC) were estimated from half‐body scans and compared with the whole‐body results. Assessment was completed using GE enCORE 11.40 software. Results: In comparing left‐ and right‐side scans to whole‐body scans, there was significant correlation for all body composition variables (p ≤ 0.005, R² = 0.996–1.0). Bland Altman analyses also showed high levels of agreement between half‐body estimates and whole‐body measurements. Conclusion: This study supports using a half‐body scan methodology for percent fat, total mass, fat mass, lean mass, and BMC as a valid alternative to full‐body analysis in obese children and youth.     

Does leptin play a role in obesity–asthma relationship?

The increase of asthma has paralleled the rising obesity during the past decades. Obesity is characterized by the increase of leptin in the circulation. Leptin is an obesity gene product, and it can stimulate the production of pro-inflammatory mediators, such as tumor necrosis factor (TNF)-α, interleukin (IL)-6 and interferon (IFN)-γ. There is a link between leptin and asthma, especially in children. It remains unclear however, if leptin is in the pathway of obesity–asthma relationship and if it plays a distinctive role in asthma in obese vs. non-obese subjects. Since leptin is in a positive feedback loop with the pro-inflammatory cytokines such as TNF-α, there is a possibility that leptin is involved as a regulatory rather than an etiologic mechanism of asthma development. Weight loss is associated with decreased circulating leptin concentration in children. Weight control program may need to be considered in the treatment of asthma in obese children.     

Effects of individual factors on adolescent obesity: Study in Turkey

Background: The aim of the present study was to investigate the effects of sociodemographic and lifestyle variables, eating habits, adolescent weight perception and weight changes on obesity in Turkish adolescents.
Methods: A total of 87 normal weight and 78 obese participants were included in the study. They were selected from adolescents who had no other health problems beside obesity. Underweight and overweight adolescents were excluded. Estimation of prevalence of overweight and obesity were based on cut-off points of the International Obesity Task Force (excess of the 85th and 95th percentiles, respectively). The prevalence of underweight was defined as the percentage of adolescents below the fifth percentiles of the US adolescents' age- and gender-specific body mass index. A structured questionnaire that included sociodemographic and lifestyle variables, eating habits, weight questions about adolescents' weight perception and weight changes was administered to the participants.
Results: In the obese group, the level of the mothers' and fathers' education was lower than in the normal group ( P  = 0.006; P  = 0.001, respectively). Obese adolescents had fewer obese people in their family ( P  = 0.001). There were statistically significant correlations between groups for fathers' occupation, joining in cultural activities, physical exercise, feeling about body shape and food preference ( P  = 0.014; P  = 0.001; P  = 0.003; P  = 0.001; P  = 0.001, respectively). Increase in weight was larger in the obese group ( P = 0.001) and those who wanted to loose weight but failed ( P  = 0.001).
Conclusions: There are associations between obesity and level of mothers' and fathers' education, number of obese people in family, fathers' occupation, joining in cultural activities, physical exercise and food preference in Turkish adolescents.     

Body mass index and thromboembolism in children with hematological malignancies

We evaluated the effects of body mass index (BMI) on the risk of thromboembolism (TE) in children (<18 years) with hematological malignancies during the period 1990-2009 (n = 359). Obesity was prevalent in 12% of patients: 6% versus 17% prior to and after the year 2000 (P = 0.02). Sixty-one (17%) patients developed TE; increasing BMI was associated with increased, but statistically insignificant risk of TE [adjusted odds ratios (OR): 0.75 (95%CI 0.32-1.77), 0.93 (95%CI 0.38-2.30), and 1.01(95%CI 0.42-2.41) for underweight, overweight, and obese group]. A large prospective study is needed to define the impact of BMI on the risk of TE in children.     

青少年儿童体质指数与血压关系探讨

目的探讨青少年儿童体质指数（BMI）与血压的关系。方法测量7963例贵阳市两城区8～17岁青少年儿童的血压、身高、体重,按WGOC标准将受检对象分为超重、肥胖及正常体重组,分析比较各组血压值差异及血压值与BMI的关系。结果①不同BMI组间收缩压（SBP）、舒张压（DBP）均值都是肥胖组〉超重组〉正常体重组（P〈0.01）;②BMI与SBP、DBP呈显著正相关（r=0.520、0.365,P均〈0.01）;控制年龄、性别、身高影响的偏相关分析显示BMI与SBP、DBP呈独立正相关（r=0.390、0.210,P均〈0.01）;③不同BMI组间高血压患病率分别为24.49%、10.76%、2.65%,肥胖组〉超重组〉非超重组（P〈0.01）;④超重、肥胖青少年儿童的高血压发病危险是体重正常青少年儿童的4倍和9倍。结论青少年儿童的BMI与血压密切相关,应重视对超重、肥胖青少年的行为干预。     

Descriptive epidemiology of small screen recreation among Australian adolescents

AIM: To describe the epidemiology of small screen recreation (SSR) that is: television, computer, video, and DVD use among school students aged 11-15 years in New South Wales, Australia. METHODS: Cross-sectional representative population survey (n=2750) of 45 primary and 48 secondary schools in rural and urban areas. Self-reported time spent in SSR was categorised according to national guidelines into less than 2 h per day (low users) or 2 or more hours per day (high users). RESULTS: Of primary and secondary school students, 53% and 72%, respectively, were high users of SSR. Boys spent significantly more time in SSR and were more likely to be high users of SSR compared with girls. For primary students, rural boys had a higher prevalence of high SSR use than urban boys (odds ratio (OR) 1.9, 95% confidence interval (CI) 1.0-3.5), while overweight girls had a higher prevalence than healthy-weight girls (OR 1.8, 95% CI 1.2-2.8). For secondary students, rural boys had a lower prevalence of high SSR use than urban boys (OR 0.5, 95% CI 0.3-0.6), and girls from high SES backgrounds had a lower prevalence than girls from low socio-economic status backgrounds (OR 0.6, 95% CI 0.3-1.0). CONCLUSION: The majority of school students in New South Wales exceed the national guidelines for SSR. Reducing the time spent in SSR among young people is one potential approach to increasing energy expenditure and reducing adiposity or maintaining a healthy weight. First steps for intervention strategies among school-age children to reduce SSR could include teaching awareness skills and self-monitoring techniques.     

Growth charts for use in Australia

Growth charts for use in Australia have recently been modified. Changes have been made to both height for age and weight for age charts as well as body mass index for age. The charts are now based on the published CDC 2000 growth data which are more contemporary than the data used to construct the previous charts. A first centile for height for age has been included as this is used as a screening tool for the provision of growth hormone to children in Australia. The calculation of a precise first centile has been possible as the CDC data includes LMS values which have other significant advantages in the creation of the growth charts. It is noteworthy that the most recently collected anthropometric data for weight (and hence body mass index) have not been included in the calculation of these two charts as it was believed that increasing numbers of children who are overweight or obese in the population would skew these charts in an undesirable way. Height velocity for age and other charts remain unchanged.