Obesity, overweight and thinness in schoolchildren of the city of Florianópolis, Southern Brazil

OBJECTIVE: To assess the prevalence of obesity, overweight (including obesity) and thinness in children of the city of Florianopolis (southern Brazil). DESIGN: Cross-sectional study. SUBJECTS: Representative sample of 7-10-y-old schoolchildren of the first four grades of elementary schools (1432 girls, 1504 boys). METHODS: Measurements of weight, height and triceps skinfold thickness (TSF) were taken following standard techniques. The body mass index (BMI) was computed as weight/height2. Nutritional status was defined using two references: (1) the Must et al reference for BMI and TSF to define thinness, overweight and obesity (5th, 85th and 95th percentiles, respectively); (2) the International Obesity Task Force (IOTF) BMI cutoffs to define overweight and obesity. RESULTS: Using BMI, according to the Must et al, and IOTF references, the prevalence of obesity was 10.6 and 5.5%, respectively; overweight (including obesity) affected 26.2 and 22.1% of children, respectively. According to the Must et al reference, the prevalence of thinness was 3.2%. Using TSF rather than BMI, according to the Must et al references, fewer children were classified as obese (8.0%) or overweight (20.2%) and more children were classified as thin (4.9%). CONCLUSION: This study supports the previously reported high frequencies of childhood overweight and obesity in developing countries. The data allow comparisons with other studies carried out in Brazil and other parts of the world.     

Utility of childhood BMI in the prediction of adulthood disease: comparison of national and international references

OBJECTIVE: To determine whether the U.S. Centers for Disease Control and Prevention (CDC; CDC Reference) or International Obesity Task Force (IOTF; IOTF Reference) BMI cut-off points for classifying adiposity status in children are more effective at predicting future health risk. RESEARCH METHODS AND PROCEDURES: The sample (N=1709) included 4- to 15-year-old (at baseline) boys and girls from the Bogalusa Heart Study. Overweight and obesity status were determined using both the CDC Reference and IOTF Reference BMI cut-off points at baseline. The ability of childhood overweight and obesity, determined from the two BMI classification systems, to predict obesity and metabolic disorders in young adulthood (after a 13- to 24-year follow-up) was then compared. RESULTS: Independently of the classification system employed to determine adiposity based on childhood BMI, the odds of being obese and having all of the metabolic disorders in young adulthood were significantly (p<0.05) higher in the overweight and obese groups by comparison with the nonoverweight groups. Childhood overweight and obesity, determined by both the CDC Reference and IOTF Reference, had a low sensitivity and a high specificity for predicting obesity and metabolic disorders in young adulthood. Overweight and obesity as determined by the CDC Reference were slightly more sensitive and slightly less specific than the corresponding values based on the IOTF Reference. DISCUSSION: Overweight and obesity during childhood, as determined by both the CDC and IOTF BMI cut-off points, are strong predictors of obesity and coronary heart disease risk factors in young adulthood. The differences in the predictive capacity of the CDC Reference and IOTF Reference are, however, minimal.     

中国2～18岁儿童青少年超重和肥胖筛查体重指数界值点的研究

目的 研究中国2～18岁儿童青少年超重、肥胖筛查体重指数(BMI)界值点.方法 在中国0～18岁儿童青少年BMI生长参照值的基础上,根据常用的超重、肥胖筛查界值点选择方法(与成年人界值点接轨法、百分位法或Z分值法),初步分别确定[BMI 24kg/m2 (BMI24)、28 kg/m2(BMI28)]、(P85、P95)和(Z1、Z2)三组界值点,通过对不同界值点进行差值和检出率比较,并与中国肥胖问题工作组(WGOC)和国际肥胖问题工作组(IOTF)的超重、肥胖界值点做对比分析,最后确定适宜界值点.结果 按照不同的超重、肥胖筛查BMI界值点选择方法获得三组界值点,不同界值点之间存在不同程度差异,但在超重合并肥胖检出率上差异相对较小.与WGOC相比,男章超重、肥胖及女童肥胖界值点非常接近,女童在8.5～15.5岁其超重界值点比WGOC标准低0.3～1.0 kg/m2,通过筛查"2004年北京市儿童代谢综合征调查"数据库,女童超重检出率比WGOC标准高约3.4%.结论 采用与成年人界值点接轨法(BMI24、BMI28)获得的中国2～18岁儿童青少年超重、肥胖筛查BMI界值点是适宜的,实现了在使用BMI指标上年龄的连贯性和筛查标准的一致性.     

Central and total adiposity are lower in overweight and obese children with high cardiorespiratory fitness

OBJECTIVE: To examine the influence of cardiorespiratory fitness on total and truncal fatness in children. It was hypothesised that high cardiorespiratory fitness would result in lower total and central obesity. DESIGN: Observational cohort study. SETTING: Primary and secondary schools in Athens, Greece. SUBJECTS: A total of 1362 healthy children aged 6-13 y (742 boys and 620 girls). METHODS: Anthropometric data (height, body mass, four skinfolds thickness) were collected and per cent body fat was calculated. Body mass index (BMI) sex- and age-specific cutoff points were used for overweight and obesity definition and children were placed in two groups: overweight/obese and nonoverweight. Cardiorespiratory fitness (CRF) was assessed with the endurance shuttle-run test. Participants were grouped into high (upper two quintiles) and low (lower two quintiles) CRF based on age and sex distributions. T-test and Mann-Whitney test were used for comparisons between fit and unfit children within each BMI category. RESULTS: Sum of skinfolds, subscapular and truncal skinfold thickness, BMI and per cent body fat were lower in overweight and obese youths with high CRF in comparison with youths at the same BMI category with low CRF (P<0.01). The beneficial effect of high CRF was also presented in nonoverweight children (P<0.01). The influence of CRF on body composition remained even after correcting body fatness for BMI. CONCLUSIONS: Central and total obesity were lower in overweight and obese children with high CRF. This is the first study to show that a high CRF may reduce the hazards of obesity in children.     

Detection of overweight and obesity in a national sample of 6-12-y-old Swiss children: accuracy and validity of reference values for body mass index from the US Centers for Disease Control and Prevention and the International Obesity Task Force

BACKGROUND: For defining overweight in children, reference values for body mass index (BMI) are available from the US Centers for Disease Control and Prevention (CDC) and the International Obesity Task Force (IOTF). However, these 2 sets of reference criteria differ, and their accuracy in classifying adiposity has not yet been validated in most countries. OBJECTIVE: We compared BMI criteria from the IOTF and the CDC with percentage of body fat (%BF) from multisite skinfold thicknesses (SFTs) for identification of overweight in 6-12-y-old Swiss children. DESIGN: In a representative sample (n = 2431), weight, height, and 4 SFTs were measured. Regression and receiver operating characteristic (ROC) curves were used to evaluate BMI as an indicator of adiposity. RESULTS: BMI and %BF were well correlated (r(2) = 0.74), and the areas under the ROC curves for overweight and obesity were 0.956-0.992. The sensitivity and specificity of the IOTF and CDC overweight criteria and of the CDC obesity criteria were high. The sensitivity of the IOTF obesity criteria was only 48% and 62% in boys and girls, respectively. Overall, the performance of the CDC criteria was superior. With the use of the CDC criteria, the prevalence of overweight in girls and boys was 19.1% and 20.3%, respectively. CONCLUSIONS: BMI is an excellent proxy measure of adiposity in 6-12-y-old children. In Swiss children, both BMI criteria accurately predict overweight, but the sensitivity of the IOTF obesity criteria is poor. They failed to detect one-half of the children identified as obese on the basis of %BF from SFTs.     

Use of BMI as a measure of overweight and obesity in a field study on 5-7 year old children

Summary Objective The present field study examines the use of BMI in comparison with estimates of percent fat mass to screen for overweight and obesity in children. Design Cross-sectional field study. Setting Four waves of children 1996–1999 at Kiel, North West Germany. Subjects A representative large sample of 2286 5–7 year old children representing 40 % of the total child population examined by school physicians within the same period in Kiel. Main outcome measures BMI was compared with anthropometric measures (TSF, BSF, SIF, SSF) and bioelectrical impedance analysis (BIA). The 90^th and 97^th BMI percentiles were used as cut offs for overweight and obesity, respectively. Results BMI reached a low sensitivity to identify overweight children when compared with the two estimates of % FM (0.60 to 0.78 for girls, 0.71 to 0.82 for boys, respectively). The specificity of BMI was 93 to 95 %. By contrast, BMI reached higher sensitivity to screen for obese children of 0.83 to 0.85 for boys and 0.62 to 0.80 for girls at a concomitant specificity of 0.95 to 0.98 for boys and 0.96 to 0.97 for girls as defined by assessment of body fat mass. Comparing nutritional status of overweight children classified as overweight or non overweight by BMI shows that BMI only identified obese but not-overweight children. Conclusion BMI can be used to screen for obese children. In contrast BMI has a poor sensitivity to screen for overweight children. Body composition analysis should be used to screen for children at risk of becoming obese. Received: 10 October 2001, Accepted: 21 December 2001     

Screening performances of the International Obesity Task Force body mass index cut-off values in adolescents

OBJECTIVE: To try to improve the International Obesity Task Force (IOTF) BMI cut-off values, in terms of prediction of body fat percentage assessed by dual-energy X-ray absorptiometry (DXA), in adolescents. METHODS: Cross-sectional survey of the adolescents from the city of Zaragoza (Spain). For this analysis we have included 286 adolescents (116 boys and 170 girls) aged 13.0-17.9 years. Body mass index (BMI) was calculated as body weight (kg), divided by height (m) squared. The percentage of body fat (BF%) was estimated by the use of DXA. RESULTS: We have calculated, new BMI cut-off values (AVENA cut-offs) to predict BF%, for boys and girls in each age group. In male adolescents, sensitivity was higher with the IOTF cut-offs (0.71, 95th C.I.: 0.44, 0.90) than with the AVENA ones (0.53, 95th C.I.: 0.28, 0.77), and specificity was very similar with both cut-off values (0.86 and 0.88, respectively), the differences being not statistically significant. In girls, both sensitivities (0.75 and 0.79, respectively) and specificities (0.90 and 0.92, respectively) were very similar with both cut-off values, and the differences, not significant. CONCLUSIONS: Optimization of the IOTF BMI cut-off values, in terms of BF%, seems not to be possible in adolescents. The IOTF criteria should be used only for overweight and obesity screening; however, in clinical settings, a more accurate measure of body fat should be recommended.     

Body composition and physical fitness of undernourished South African rural primary school children

OBJECTIVE: The purpose of this study was to determine the relationships between the body composition characteristics, body mass index (BMI), sum of skinfolds (SSF), % body fat (%BF), fat-free mass (FFM) and waist-to-hip ratio (WHR), and nine physical fitness items in undernourished rural primary school children in Ellisras, South Africa. DESIGN: A cross-sectional study. SETTING: The study consisted of 462 boys and 393 girls who were aged 7-14 y. MEASUREMENTS: Five body composition measures were assessed: BMI, SSF, %BF, FFM and WHR. Nine physical fitness test items were assessed: standing long jump, bent arm hang, sit-ups, 10 x 5 m shuttle run, 50 m sprint, 1600 m run, flamingo balance, sit and reach, plate tapping. RESULTS: BMI was highly correlated with FFM (r = 0.7, P < 0.001). In line with findings from Western countries, regression coefficients (B) showed that children with higher BMI or SSF performed worse in bent arm hang (girls, B = -0.84, P < 0.001, and B = -0.06, P = 0.02, respectively) and in 1600m run (B = 6.68, P < 0.001). BMI was significantly associated with flamingo balance (B = 0.26, P = 0.04). WHR was positively associated with bent arm hang (B = 9.37, P = 0.03), and inversely with sit and reach (B = -7.48, P = 0.01). In contrast, significant relationships were found between BMI and standing long jump (B = 0.74, P = 0.04), sit and reach (B = 0.51, P < 0.001), flamingo balance (B = 0.26, P = 0.04) and plate tapping (B = -19, P = 0.01). SSF was significantly associated with sit and reach (B = 0.04, P = 0.03). Significant inverse associations were found between FFM and bent arm hang (girls, B = -0.06, P = 0.05), 1600 m run (girls, B = -2.33, P = 0.003) and 50 m run (boys, B = -0.11, P = 0.006). FFM was significantly associated with standing long jump (boys, B = 0.99, P < 0.001; girls, B = 0.73, P < 0.001), flamingo balance (B = 0.17, P < 0.001), and with sit and reach (boys, B = 0.59, P = 0.03). CONCLUSION: In the present study in undernourished children, body composition was significantly related to physical fitness, but not always in the expected direction. It is therefore important to note that in this population, BMI should not be interpreted as a measure of fatness/overweight, but rather as an indicator of muscle mass.     

Percent body fat cutoff values for classifying overweight and obesity recommended by the International Obesity Task Force (IOTF) in Korean children

OBJECTIVE: To predict the percent body fat (%BF) cutoff values corresponding to overweight and obesity recommended by the International Obesity Task Force (IOTF) in Korean children and to compare those values with the published cutoff values in Caucasian children. RESEARCH METHODS AND PROCEDURES: The sample consisted of 1083 Korean children and adolescents (555 boys and 528 girls) aged 7-18 years from 3 schools. Body mass index (BMI) and %BF using a bioelectrical impedance analyzer were measured. The classification of overweight and obesity was based on the age- and sex-specific BMI cutoff values of the IOTF guidelines. RESULTS: The predicted %BF cutoff values for overweight and obesity varied by age and sex: overweight, 17-22% in boys and 24-37% in girls; obesity, 24-30% in boys and 30-53% in girls. Those %BF cutoff values in older Korean boys tended to be lower than the published %BF cutoff values in Caucasian boys. While %BF cutoff values for overweight in Korean girls were similar to the values in Caucasian girls, %BF cutoff values for obesity in Korean girls aged 13-18 years were higher compared to cutoff values in Caucasian girls. CONCLUSION: The %BF values associated with the IOTF-recommended BMI cutoff values for overweight and obesity may require age- and sex-specific cutoff values in Korean children aged 7-18 years.     

Overweight and obesity in Irish primary schools: retrospective cohort study

BACKGROUND: This retrospective cohort study investigates the feasibility of using established methods and routinely generated data from the statutory primary school health-screening programme to estimate prevalence rates for childhood overweight and obesity in children from a rural area in the Republic of Ireland (ROI). METHOD: Paper-based records in the primary school health service for County Leitrim and parts of County Cavan in north-west of ROI were hand searched to identify children attending senior infant classes during academic year 2001/2002. Electronic calculation of body mass index (BMI) and age at examination was carried out. Application of age- and sex-specific cut-off points from International Obesity Task Force (IOTF) and United Kingdom (UK) standard definitions for childhood overweight and obesity was used to determine age- and sex-specific prevalence rates for childhood overweight and obesity. RESULTS: The eligible cohort was almost completely identified and consisted of 361 children. Weight and height measurements were available on 328 (91%) children aged between 4.22 and 7.92 years. IOTF standard application gave prevalence rates of 25% for obesity and overweight in boys and 26% in girls. With the UK growth standard, this increased to 34% in boys and reduced to 23% in girls. CONCLUSION: It is feasible to generate prevalence rates for childhood overweight and obesity from data routinely obtained through the statutory school health-screening programme in ROI. This study suggests levels of childhood overweight and obesity comparable to other Western societies. Further research on developing a universally accepted standard definition of childhood overweight and obesity is required.     

Obesity: does it occur in African children in a rural community in South Africa?

BACKGROUND: Total body fatness and a centripetal fat patterning are recognized as risk indicators of cardiovascular disease in adulthood. In this study, the development of these risk factors in rural South African children during the preschool years and first years of formal schooling is explored. METHOD: The initial cross-sectional data from the Ellisras Longitudinal Investigations in Rural Community Children Project, ongoing since 1996, were used, involving 684 boys and 652 girls, aged 3-10 years, in the Ellisras rural community. Overweight was measured using the body mass index (BMI) (kg/m2). Overfatness was based on the sum of the triceps and subscapular skinfold thicknesses. A centripetal fat patterning was measured by the sum of trunk skinfolds relative to limb skinfolds and the ratio of the subscapular to triceps skinfold. Further, the ratio of the subscapular to supraspinale skinfold was used as an indicator of lower body fat patterning. The 85th percentiles of the NHANES III were used as cutoff values for overweight, overfatness and a centripetal fat patterning. RESULTS: At ages 7 and 8 years, mean BMI was statistically significantly higher in males compared to females (P < 0.05). The log transformed supraspinale skinfold thickness was larger in females compared to males at ages 4-7 years; the log transformed subscapular skinfold was larger in girls compared to boys aged 7-10 years. Less clear patterns were found for the extremity skinfolds and the skinfold ratios. Very few children (0-2.5% in males and 0-4.3% in females) had BMI values above the NHANES III 85th percentiles, indicating a very low prevalence of overweight children in the area. About 15% of the males showed overfatness at ages 3-4 years, while low prevalence was found at older ages. CONCLUSION: Few Ellisras rural children had above normal values for BMI, indicating a low prevalence of obesity in this population. In the 3- and 4-year-old group more subjects were found to have excessive fat, as indicated by the sum of the triceps and subscapular skinfold thicknesses.     

The association of fat patterning with blood pressure in rural South African children: the Ellisras Longitudinal Growth and Health Study

BACKGROUND: Hypertension is one of the major causes of death in developed and underdeveloped nations. Essential hypertension and obesity may have their inception in childhood, with little data in African children to support these findings. Objectives were to determine the prevalence of overweight and hypertension in rural children in South Africa. Additionally, the association between fat-patterning ratios and blood pressure (BP) was investigated. METHODS: Data were collected from 1884 subjects (967 boys and 917 girls), aged 6-13 years, participating in the Ellisras Longitudinal Study. Height; weight; and triceps, biceps, subscapular, and suprailiac skinfolds were measured according to the protocol of the International Society for the Advancement of Kinanthropometry. Skinfold ratio was used as an indicator of the central pattern of body fat. Internationally recommended cut-off points for body mass index (BMI) were used. Hypertension, defined as the average of three separate BP readings where the systolic BP or diastolic BP is >or=95th percentile for age and sex, was determined. RESULTS: The prevalence of hypertension ranged from 1 to 5.8% for boys and 3.1 to 11.4% for girls, and that of overweight from 1.1 to 2.9% for boys and 0.6 to 4.6% for girls. The association between high systolic BP and high BMI was -3.0, while that for high diastolic BP and high BMI was -0.68. CONCLUSIONS: The prevalence of hypertension is evident from the age 6 years for girls, while that of overweight was low. Overweight became evident from the age 10 to 13 years for both sexes. A significant association between high diastolic BP and high BMI was noted, while children with low BMIs were less likely to be hypertensive. Investigating habitual physical activity, fitness and dietary patterns will shed more light on the association of fat patterning and BP in this population.     

乌鲁木齐市维吾尔族和汉族7～18岁人群体重指数分类标准比较

目的探讨使用偏度-中位数-变异系数法（LMS法）建立并比较乌鲁木齐市7～18岁维吾尔族（维族）和汉族青少年超重、肥胖的体重指数（BMI）分类标准。方法采用分层整群抽样方法，调查新疆乌鲁木齐市7～18岁维、汉族中小学生9146人，绘制两民族7～18岁青少年年龄别、性别BMI百分位曲线，确定18岁时分别通过国际肥胖工作组（IOTF）和中国肥胖问题工作组（WGOC）成年人超重、肥胖标准的特殊百分位数曲线，由此获得两民族7～18岁人群超重和肥胖的界值标准。结果18岁时通过25及30kg／m^2的百分位曲线：维族男生为P94.46和P99.58，维族女生为P92.44和P99.64，汉族男生为P85.05和P97.26，汉族女生为P90.92和P99.03；通过24及28kg／m^2的百分位曲线维族男生为P90.54和P98.86，维族女生为P86.96和P98.77，汉族男生为P78.98和P94.72，汉族女生为P86.15和P97.56。结论BMI分布具有民族特异性；对维族青少年超重、肥胖筛检时建议参考使用该研究标准。     

Diagnosis of overweight and obesity in adolescents from the 1993 Pelotas Birth Cohort Study, Rio Grande do Sul State, Brazil: comparison of two diagnostic criteria

Various cut-off points for body mass index have been proposed to assess nutritional status in adolescents. The aim of this study was to compare two methods for evaluating overweight and obesity. In 2004-5, 4,452 adolescents from the 1993 Pelotas (Brazil) birth cohort study were evaluated, representing 87.5% of the original cohort. Overweight and obesity were evaluated using the methods proposed by the World Health Organization (WHO) and International Obesity Task Force (IOTF). Prevalence of overweight was similar when comparing the two methods (WHO: 23.2%; IOTF: 21.6%). Prevalence of obesity was higher according to the WHO criterion (total sample: 11.6%; boys: 15.1%; girls: 8.2%) as compared to IOTF (total sample: 5.0%; boys: 5.6%; girls: 4.4%). The kappa statistic was around 0.9 for determining overweight and 0.4 for obesity. The IOTF classification showed high specificity in comparison to the WHO criterion for determining overweight and obesity. However, sensitivity was high for overweight but low for obesity. Our data show that the IOTF classification underestimates the prevalence of obesity in early adolescence.     

Prevalence of overweight and obesity in Greek school-aged children and adolescents

The aim of the present study, which was part of the Health Behavior in School Aged Children (HBSC) study, was to provide national estimates for overweight and obesity in Greek school-aged children and adolescents. A nationwide multistage procedure was followed to obtain a representative sample of children and adolescents aged 11.5, 13.5 and 15.5 y. The resultant sample consisted of 4299 students, 51.3% girls and 48.7% boys. Self-reported weight and height data were used. According to the body mass index cutoff points adopted by the International Obesity Task Force (IOTF), 9.1% of girls and 21.7% of boys were classified as overweight, and 1.2% of girls and 2.5% of boys as obese. Corresponding values using CDC growth charts were 8.1% of girls and 18.8% of boys for overweight, and 1.7% of girls and 5.8% of boys for obese. Compared to most other western countries, the prevalence of obesity is lower in Greek children aged 11-16 y.     

Anthropometric indices of school children and familiar risk factors

BACKGROUND: Overweight in adolescence predicts adverse health effects in adulthood. We carried out a primary school health program and assessed children's growth and body composition. METHODS: Were screened 869 (448 M, 421 F) primary school children: height, weight, four skinfolds, and four circumferences were measured. A family-reported questionnaire was used to determine family composition, history, and lifestyle. RESULTS: Age was 118 +/- 5 months, BMI 18 +/- 3 kg/m(2). No difference by gender was observed as for BMI or blood pressure. Girls had higher skinfold thickness at the biceps (BCF), triceps (TCF), subscapular (SSF), and suprailiac (SIF) areas (P < 0.001), hip and thigh circumferences (P < 0.01), body fat percentage (P < 0.001). Boys had higher waist circumference (P < 0.01), waist/thigh ratio, and conicity index (P < 0.001). Offspring BMI was correlated with birth weight (P < 0.05), parental BMI and scholarship level (P < 0.001), children blood pressure (P < 0.001), and hours per day spent in television viewing (P < 0.01). Family history for diabetes was associated with higher BMI, SSF, waist circumference (P < 0.05), and upper thigh (P < 0.01). Family history for hypertension was associated with higher SSF/TCF ratio (P < 0.05). CONCLUSIONS: Three of 869 children had BMI >30 kg/m(2) (2 boys and 1 girl), 33 had BMI >25 kg/m(2) (17 boys and 16 girls). The percentages of children who could be considered overweight (BMI >/=95(th) percentile of age- and sex-specific NHANES I reference data) were boys, 10.0%, and girls, 9.3%. Anthropometric and anamnestic data on child and family yield more accurate estimates of risk profile: fat distribution seems relevant for metabolic and cardiovascular disorders.     

Inconsistencies in bioelectrical impedance and anthropometric measurements of fat mass in a field study of prepubertal children

The present study examined the consistency of bioelectrical impedance analysis (BIA) and anthropometric measurements in body composition analysis in a field study of prepubertal children using a representative group of 2286 5-7-year-old children from Kiel, north-west Germany. Body composition was assessed using anthropometric measures (A; four skinfolds) and BIA. Various published algorithms (according to Lohmann (1986) and Deurenberg et al. (1990) for A, Kushner et al. (1992), Schaefer et al. (1994) and Wabitsch et al. (1996) for BIA and Goran et al. (1996) for a combined approach) were used to estimate body composition. Using A resulted in a sum of four skinfolds varying between age-dependent median values of 24.0 and 28.2 mm in boys and 30.5 and 33.3 mm in girls. When fat mass (FM) was calculated from A, age- and algorithm-dependent differences in median values were observed, with values varying between 8.5 and 14.6% for boys and 1.11 and 14.9% for girls. Using different algorithms (Lohmann (1986) v. Deurenberg et al. (1990)) only minor inconsistencies were observed. BIA-derived resistance index (height2/resistance) varied between 18.8 and 24.4 cm2/omh for boys and 17.1 and 19.0cm2/ohm for girls. Using four different algorithms to estimate FM from BIA data resulted in high intra-individual variances in percentage FM (from 13.8 to 33.4) as well as in the prevalence of overweight (from 14.7 to 98.4% for boys and from 42.3 to 98.5 % for girls). Data obtained using the different BIA algorithms showed some, or even marked, inconsistencies as well as systematic deviations (an overestimation of FM at low percentage FM, Schaefer et al. (1994) v. Wabitsch et al. (1996)). When comparing BIA with A, BIA systematically overestimated FM. The differences between the results were influenced by BMI, gender and height. Considerable inconsistencies were observed at low BMI (<10th percentile) for girls and for small children. Although the within-observer as well as between-observer CV for both techniques are acceptable, we recommend caution in relation to the algorithms used for data analysis. The use of an interchange table of percentage FM derived from different algorithms for different percentile groups of skinfold thicknesses is recommended.     

Screening Performances of the International Obesity Task Force Body Mass Index Cut-Off Values in Adolescents

Objective: To try to improve the International Obesity Task Force (IOTF) BMI cut-off values, in terms of prediction of body fat percentage assessed by dual-energy X-ray absorptiometry (DXA), in adolescents.

Methods: Cross-sectional survey of the adolescents from the city of Zaragoza (Spain). For this analysis we have included 286 adolescents (116 boys and 170 girls) aged 13.0–17.9 years. Body mass index (BMI) was calculated as body weight (kg), divided by height (m) squared. The percentage of body fat (BF%) was estimated by the use of DXA.

Results: We have calculated, new BMI cut-off values (AVENA cut-offs) to predict BF%, for boys and girls in each age group. In male adolescents, sensitivity was higher with the IOTF cut-offs (0.71, 95^th C.I.: 0.44, 0.90) than with the AVENA ones (0.53, 95^th C.I.: 0.28, 0.77), and specificity was very similar with both cut-off values (0.86 and 0.88, respectively), the differences being not statistically significant. In girls, both sensitivities (0.75 and 0.79, respectively) and specificities (0.90 and 0.92, respectively) were very similar with both cut-off values, and the differences, not significant.

Conclusions: Optimization of the IOTF BMI cut-off values, in terms of BF%, seems not to be possible in adolescents. The IOTF criteria should be used only for overweight and obesity screening; however, in clinical settings, a more accurate measure of body fat should be recommended.     

Obesity and socioeconomic status in children of Tijuana

BACKGROUND: Although obesity has been associated with socioeconomic status among Hispanics living in the United States, little is known about whether a similar association exists among Hispanics living in Mexico, particularly among those living along the U.S.-Mexico border. OBJECTIVE: To determine the prevalence of obesity and its association with socioeconomic status in Mexican schoolchildren attending public and private schools in Tijuana, Baja California. METHODS: Anthropometric measurements and socioeconomic status were assessed in a cross-sectional study of 1172 school children, aged 6 to 13 years from 55 schools in Tijuana in 2001-2002. Underweight (body mass index [BMI] for age 5th percentile or lower), risk of overweight (BMI at 85th percentile or higher), and overweight (BMI greater than 95th percentile) were assessed using charts published by the Centers for Disease Control and Prevention. RESULTS: Abnormalities in weight were found in 46.3% of 587 boys and 43.7% of 585 girls in the study. Undernutrition was found in 3.7% of the boys and 3.8% of the girls. The general prevalence of overweight was 23.2% for boys and 21.7% for girls. Children living in low-income neighborhoods had the thickest biceps skinfolds (p<0.01), while children living in moderate-income neighborhoods and attending public schools had the thickest triceps skinfolds (p<0.001). Although boys living in high socioeconomic status neighborhoods were at decreased risk for being overweight, boys and girls attending private schools had a 75% increased risk (odds ratio, 1.75; confidence interval, 1.22-2.52) of being overweight than children attending public schools. CONCLUSIONS: Adiposity varies by type of school and neighborhood socioeconomic status. The biphasic curve in risk for being overweight associated with neighborhood socioeconomic status suggests that Mexican children living along the U.S. border may be experiencing a nutrition transition with respect to an increased risk of obesity and related chronic disease.