Validity of BMI as a measure of obesity in Australian white Caucasian and Australian Sri Lankan children

Background: Body mass index (BMI) is used to diagnose obesity. However, its ability to predict the percentage fat mass (%FM) reliably is doubtful. Therefore validity of BMI as a diagnostic tool of obesity is questioned. Aim: This study is focused on determining the ability of BMI-based cut-off values in diagnosing obesity among Australian children of white Caucasian and Sri Lankan origin. Subjects and methods: Height and weight was measured and BMI (W/H²) calculated. Total body water was determined by deuterium dilution technique and fat free mass and hence fat mass derived using age- and gender-specific constants. A %FM of 30% for girls and 20% for boys was considered as the criterion cut-off level for obesity. BMI-based obesity cut-offs described by the International Obesity Task Force (IOTF), CDC/NCHS centile charts and BMI-Z were validated against the criterion method. Results: There were 96 white Caucasian and 42 Sri Lankan children. Of the white Caucasians, 19 (36%) girls and 29 (66%) boys, and of the Sri Lankans 7 (46%) girls and 16 (63%) boys, were obese based on %FM. The FM and BMI were closely associated in both Caucasians (r?=?0.81, P<0.001) and Sri Lankans (r?=?0.92, P<0.001). Percentage FM and BMI also had a lower but significant association. Obesity cut-off values recommended by IOTF failed to detect a single case of obesity in either group. However, NCHS and BMI-Z cut-offs detected cases of obesity with low sensitivity. Conclusions: BMI is a poor indicator of percentage fat and the commonly used cut-off values were not sensitive enough to detect cases of childhood obesity in this study. In order to improve the diagnosis of obesity, either BMI cut-off values should be revised to increase the sensitivity or the possibility of using other indirect methods of estimating the %FM should be explored.     

Validity of newly-developed BMI and waist cut-off values for Sri Lankan children

Background: Excess body fat leads to obesity-related morbidity and population/ethnicity-specific cut-off values of anthropometric measures are useful for better diagnosis. This study assesses the suitability of newly-developed Sri Lankan anthropometric cut-off values in the diagnosis of obesity in Sri Lankan children.

Methods: A cross-sectional study was conducted at University of Colombo, Sri Lanka involving 5–15 year old children. Height, weight, waist (WC), and hip (HC) circumferences were measured. Total body fat (FM) was measured using whole body BIA. WHR and WHtR were calculated. Validity of anthropometric measures in detecting childhood obesity (Sri Lankan BMI/WC; IOTF, WHO, British and CDC BMI and British WC cut-off values) were evaluated.

Results: Nine hundred and twenty children were assessed. FM showed significant associations with BMI (r = 0.92, p < 0.001), WC (r = 0.90, p < 0.001) and HC (r = 0.85, p < 0.001), but poor association with WHR (r = 0.17, p < 0.001). However, WHtR had a high association with FM (r = 0.75, p < 0.001) and %FM (r = 0.78, p < 0.001). Based on %FM cut-offs, 85 (22.8%) girls and 101 (18.5%) boys were obese. All international anthropometric cut-off values under-estimated obesity. Sri Lankan WC and BMI cut-off values over-estimated obesity. International BMI based cut-off values had high specificity (>99%) but a low sensitivity (～12–33%), while Sri Lankan BMI cut-off values had high sensitivity (>93.1) but low specificity (>79.7).

Conclusions: Internationally available BMI cut-off values are poor in diagnosing obesity in Sri Lankan children. Newly developed Sri Lankan BMI cut-off values for children improved the diagnosis. WC can be used successfully as an alternative diagnostic tool of obesity.     

Alu insertions versus blood group plus protein genetic variability in four Amerindian populations

Background: Various charts based on body mass index (BMI) and per cent body fat (%BF) are used to classify childhood body composition but outcomes may vary.

Aim: The study investigated variation in incidences of childhood obesity as depicted by four classification charts.

Subjects and methods: BMI and DXA-derived %BF were assessed in 741 children. Incidences of overweight and obesity were compared between two BMI charts and two bioelectrical impedance (BIA)-based %BF charts.

Results: The International Obesity Task Force (IOTF)-adopted BMI chart designated 21%, 6% (boys), and 26%, 9% (girls) as overweight and obese, respectively. Corresponding figures using the USA CDC BMI chart were 27%, 11% (boys) and 27%, 12% (girls). Using a USA-derived %BF chart incidences were 17%, 2% (boys) and 21%, 8% (girls) and using a UK-derived %BF chart 51%, 24% (boys) and 53%, 36% (girls). Sensitivity of BMI varied according to the %BF reference chart.

Conclusions: In contrast to the BMI-based charts, there were considerable variations in depicted incidences of obesity between the %BF-based charts. These discordances were considered to result from previously reported variation within and between BIA and DXA %BF assessments underlying the charts. The present study highlights the need for valid, reliable, unchanging BIA and DXA procedures.     

Anthropometry of 5-19-year-old Tongan children with special interest in the high prevalence of obesity among adolescent girls

BACKGROUND: Despite much concern about adult obesity among Pacific Islanders, childhood obesity has seldom been investigated. AIM: Based on the anthropometry of Tongan children aged 5-19 years, this study aims to elucidate age and sex differences in obesity prevalence calculated from BMI and its relation to body fat estimated by skinfold thicknesses. SUBJECTS AND METHODS: 895 students, aged 5-19 years, in the most modernized island and a remote island, were measured for stature, body weight, circumferences at waist, hip and mid-upper arm, and skinfold thicknesses at biceps, triceps and subscapular. The prevalence of overweight and obesity was calculated using the reference data of the International Obesity Task Force (IOTF) and the Centers for Disease Control and Prevention (CDC). RESULTS: The prevalence of obesity of Tongan adolescent girls defined by the IOTF and CDC references was 19.4% and 22.8%, respectively, being considerably higher than that of not only juvenile girls but also adolescent boys. Among adolescents, the girls' BMI was positively correlated with fat mass whereas in boys it was not. The sex difference in adolescents was parallel to that in adults, being attributable to gender differences in daily behavioural patterns. CONCLUSIONS: Among Tongan adolescents, obesity prevalence in girls was much higher than in boys, in association with fat accumulation in the former.     

Behavioral and physiological indices related to BMI in a cohort of primary schoolchildren in Greece.

The purpose of this study was to investigate the differences between normal weight and overweight primary schoolchildren in terms of certain cardiovascular disease (CVD) risk factors and furthermore to identify behavioral correlates significantly affecting their body mass index (BMI). The sample consisted of 198 children with a mean age of 11.5 +/- 0.4 years (106 females and 92 males). Data was obtained on children anthropometry, plasma lipids, plasma glucose, dietary intake, cardiorespiratory fitness, and physical activity. Significant gender differences were observed for most of these parameters, with boys being more active and fit but also spending more time on sedentary activities and exhibiting higher intake of energy and fat compared to girls. Using the International Obesity Task Force's (IOTF) BMI cut-off points, the prevalence of overweight and obesity was estimated to be 35.6% and 6.7% among boys and 25.7% and 6.7% among girls, respectively. Overweight and obese children had higher levels of plasma triglycerides (TG) and total cholesterol to HDL-cholesterol (TC/HDL-C) ratio and lower levels of HDL-C and physical fitness compared to their normal-weight peers. Among the behavioral variables tested, only participation in organized sports, cardiorespiratory fitness, and TV watching were significantly correlated with BMI, while energy and fat intake were found to have no significant effect. The current study suggests that even in childhood, overweight and obesity are indicative of an unfavorable lipidemic profile. Among the behavioral parameters known to affect BMI, those found to exert a significant effect were organized physical activities, cardiorespiratory fitness, and TV watching, but not energy or fat intake.     

Abdominal Obesity in German Adolescents Defined by Waist-to-Height Ratio and Its Association to Elevated Blood Pressure: The KiGGS Study

ObjectiveThe aim of this study was to compare the fixed 0.5 cut-off and the age- and sex-specific 90th percentile (P90) for waist-to-height ratio (WHtR) in German adolescents with respect to the prevalence of abdominal obesity and to compare the screening ability of WHtR and BMI to identify hypertensive blood pressure (BP) values.MethodsBetween 2003 and 2006, the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) was carried out including 3,492 boys and 3,321 girls aged 11-17 years. Abdominal obesity was assessed by two WHtR cut-points (P90; 0.5). Hypertensive BP was defined as BP exceeding age-, sex- and height-specific 95th percentiles or the adult threshold for hypertension (140/90 mm Hg).ResultsAgreement between the WHtR cut-offs was very good (Kappa 0.89 for boys; 0.81 for girls), and the prevalence of abdominal obesity was slightly higher using P90 (boys 12.0%; girls 11.3%) compared to 0.5 (boys 10.7%; girls 8.0%). WHtR and BMI-for-age had equivalent ability to discriminate hypertensive BP (ROC-AUC < 0.7; sensitivity of the 0.5 cut-off for detecting hypertensive BP < 30%).ConclusionThe fixed 0.5 WHtR cut-off can be used in German adolescents to characterize abdominal obesity. However, WHtR is not suitable as a screening tool for hypertensive BP in adolescents.Key Words: Body mass index, Waist-to-height ratio, Abdominal obesity, Blood pressure, Adolescents     

Prevalence of Thinness,Overweight, Obesity,and Central Obesity in Finnish School-Aged Children: A Comparison of National and International Reference Values

IntroductionThe global epidemic of obesity concerns children, and monitoring the prevalence is of highest priority. Body mass index (BMI) with age- and sex-specific cutoff values determines weight status in children, although multiple reference systems exist. Our aim was to compare the prevalence for thinness, normal weight, overweight, and obesity in Finnish school-aged children according to national and international reference values, as well as to determine which cutoff values for overweight agree with the criteria for central obesity.MethodsThis study includes 10,646 children aged 9–12 years from the Finnish Health in Teens cohort. Height, weight, and waist circumference were measured in 2011–2014. BMI (weight [kg]/height [m]²) and the waist-to-height ratio (WHtR; waist [cm]/height [cm]) were calculated. The WHtR cutoff of >0.5 indicated central obesity. We compared the sex-specific prevalence of thinness, overweight, and obesity using the International Obesity Task Force (IOTF), World Health Organization (WHO) and Finnish (FIN) BMI-for-age reference values, as well as these three against central obesity based on the WHtR.ResultsThe prevalence of thinness, overweight, and obesity were 11.0%, 12.7%, and 2.6%, respectively, using IOTF; 2.6%, 15.9%, and 5.2% using WHO; and 5.1%, 11.4%, and 2.2% using FIN. Overweight and obesity were more common in boys than girls using WHO and FIN, while thinness was more common in girls using IOTF and FIN. IOTF versus WHO exhibited moderate agreement (κ = 0.59), which improved for IOTF versus FIN (κ = 0.74). Of those classified as overweight by WHO, 37% and 47% were regarded as normal weight according to IOTF and FIN, respectively. The prevalence of central obesity was 8.7%, and it was more common in boys than girls. WHO provided the highest sensitivity: 95% of individuals with central obesity were classified with overweight or obesity. Using FIN provided the highest specificity (93%).ConclusionOur findings show that WHO overestimates the prevalence of overweight and obesity, while IOTF overrates thinness. Thus, comparing prevalence rates between studies requires caution. The novelty of this study is the comparison of the cutoff values for overweight with central obesity. The choice of reference system affects the generalizability of the research results.     

Weight status of indigenous youth in Oaxaca,southern Mexico: concordance of IOTF and WHO criteria

Abstract

Purpose: To compare the prevalence of thinness, overweight and obesity with IOTF and WHO criteria among indigenous school youth from the state of Oaxaca, southern Mexico.

Methods: The sample included 11?454 indigenous youth (6216 boys, 5238 girls) 6–14 years of age. Heights and weights were measured in 2007 by trained staff. BMIs were calculated and classified as severely thin, moderately thin, normal, overweight or obese using age- and sex-specific IOTF and WHO cut-offs. Prevalence, percentage agreement between classifications, Spearman rank order correlations and Kappa coefficients were calculated.

Results: Prevalence of overweight and obesity was higher with WHO than IOTF criteria, while prevalence of severe and moderate thinness did not appreciably differ between criteria. Weight status with the two criteria was discordant in 839 boys (13.5%) and 383 girls (7.3%) and more often for overweight and obesity than thinness. Percentage agreement, correlations and Kappa coefficients were moderate-to-high and were higher in girls than boys.

Conclusion: Prevalence of overweight and obesity among indigenous youth in Oaxaca was higher with WHO than IOTF criteria, whereas prevalence of severe and moderate thinness was similar. Differences in estimates for overweight and obesity have implications for surveillance.     

中国新疆地区哈萨克族7～18岁中小学生体重指数分布和超重肥胖筛查参考值的建立

目的建立中国新疆地区哈萨克族7～18岁中小学生超重和肥胖的体重指数（BMI）百分位曲线和界值点参考标准。方法采用横断面调查研究,在中国新疆阿勒泰市及其所属乡镇的中小学采用整群随机抽样方法抽取4所学校（共49个班级）同意参加调查的哈萨克族7～18岁中小学生为调查对象。采集性别、年龄、身高和体重测量资料;应用偏度-中位数-变异系数法建立哈萨克族7～18岁中小学生的BMI百分位曲线;利用儿童青少年超重和肥胖的BMI百分位数曲线在18岁通过国际肥胖工作小组（IOTF）定义的成人超重和肥胖BMI界值点（25kg·m^-2/30kg·m^-2）和中国肥胖问题工作组（WGOC）定义的界值点（24kg·m^-2和28kg·m^-2）的方法,计算出哈萨克族7～18岁各年龄超重和肥胖的BMI界值点。结果共采集7～18岁中小学生2487名,其中男1158名,女1329名。①按照IOTF标准,超重和肥胖的BMI百分位曲线：男性分别为P88.63和P98.28,女性分别为P84.41和P98.12;按照WGOC标准,超重和肥胖的BMI百分位数曲线：男性分别为P92.96和P99.28,女性分别为P90.53和P99.38。②哈萨克族男性超重和肥胖BMI标准曲线低于WGOC和IOTF标准;女性肥胖标准曲线13～14岁前低于WGOC和IOTF标准,之后略高于WGOC和IOTF标准。③哈萨克族男性超重、肥胖的界值百分位曲线均低于或接近的汉族和维吾尔族水平;哈萨克族女性超重界值百分位曲线在14岁前介于汉族和维吾尔族间,之后接近或达到汉族水平;肥胖界值百分位曲线在10岁前低于汉族和维吾尔族水平,14岁后达到或接近汉族水平。结论儿童青少年BMI分布有显著的地域差异和民族差异,哈萨克族中小学生超重和肥胖BMI界值标准不同于IOTF和WGOC所建议的相应标准。因此哈萨克族中小学生超重、肥胖人群的筛查可以参考本研究建立的标准。     

Weight and body mass index (BMI): current data for Austrian boys and girls aged 4 to under 19 years

Background: BMI reference charts are widely used to diagnose overweight, obesity and underweight in children and adolescents.

Aim: To provide up-to-date national reference values for Austria.

Methods: A cross-sectional sample of over 14?500 children and adolescents (4–19 years) stratified by provinces according to age- and sex-specific population proportions was drawn via schooling institutions (kindergartens, schools and vocational colleges). The generalized additive models for location, scale and shape were used for a flexible estimation of percentile curves.

Results: Austrian boys and girls have higher average weight compared with previous prevalence data. BMI centiles matching BMI values at age 18 years, which are used for defining thinness, overweight and obesity in adults, were calculated. In Austria, using reference values as thresholds, ～18% of boys and 12% of girls are overweight (with thresholds passing through BMI 25.00–29.99?kg/m² in adults) and 5% of boys and 3% of girls are obese (with thresholds passing through BMI ≥30.00?kg/m² in adults).

Conclusion: Overweight and obesity are common in Austria and their prevalence is increasing (using the same IOTF reference for international comparison). Up-to-date national BMI reference values are provided to classify children and adolescents according to the proposed overweight and obesity thresholds.     

High prevalence of overweight and obesity among inner city Chinese children in Shanghai, 2011

Background: In China, the prevalence of overweight and obesity appears to be increasing at unacceptable levels among young people living in major cities undergoing rapid economic growth.

Objective: To report the prevalence of overweight and obesity among Shanghai inner city youth using the recently published International Obesity Task Force (IOTF) Asian definition.

Methods: Secondary analysis of children aged 8–15 years who participated in the Shanghai Schools’ Physical Fitness Examinations, a representative school-based survey. Height and weight were measured and body mass index (kg/m²) was calculated. The prevalence of overweight and obesity was determined using the IOTF children’s BMI cut-points for Asian populations, equivalent to an adult BMI of 23?kg/m² (overweight) and 27?kg/m² (obese).

Results: The prevalence of combined overweight and obesity was 49.1% for boys and 30.8% for girls aged 8–15-years. Almost one-in-five boys were obese, compared with 8.4% of girls. In boys the prevalence of overweight appeared to increase from age 10 years.

Conclusion: The high prevalence of combined overweight and obesity among urban Chinese youth, especially among boys, requires immediate health promotion intervention.     

Body Fat Percentile Curves for Korean Children and Adolescents: A Data from the Korea National Health and Nutrition Examination Survey 2009-2010

A valid assessment of obesity in children and adolescents is important due to significant change in body composition during growth. This study aimed to develop percentile curves of body fat and fat free mass using the Lambda, Mu, and Sigma method, and to examine the relationship among body mass index (BMI), fat mass and fat free mass in Korean children and adolescents, using the Korea National Health and Nutrition Examination Survey (KNHANES) 2009-2010. The study subjects were 834 for boys and 745 for girls aged between 10 and 18 yr. Fat mass and fat free mass were measured by dual-energy x-ray absorptiometry. The patterns of development in body fat percentage, fat mass and fat free mass differed for boys and girls, showing a decreased fat mass with an increased fat free mass in boys but gradual increases with age in girls. The considerable proportion of boys and girls with relatively normal fat mass appeared to be misclassified to be at risk of overweight based on the BMI criteria. Therefore, the information on the percentiles of body fat and fat free mass with their patterns would be helpful to complement assessment of overweight and obesity based on BMI for Korean children and adolescents.     

Overweight and obesity in affluent school children of Punjab

In the present cross-sectional study, an attempt has been made to report the prevalence of overweight and obesity in school-going children of the affluent families of Punjab. A total of 1000 children (490 boys and 510 girls) were measured for height and weight. Overweight and obesity were assessed using age and sex-specific body mass index (BMI) cut-off points. In the present study, 12.24% boys and 14.31% girls were overweight, and 5.92% boys and 6.27% girls were obese. The prevalence of overweight and obesity among the affluent school children of Punjab was as high or higher as in some developed countries.     

Prevalence of overweight and obesity in 7-9-year-old Portuguese children: trends in body mass index from 1970-2002.

The aim of this study was to assess the prevalence of overweight and obesity in Portuguese children age 7-9 years and to analyze trends in body mass index (BMI) from 1970-2002. Data were collected from October 2002 to June 2003 in a random sample of Portuguese children. Height and weight were measured and BMI (Kg/m(2)) was calculated. The International Obesity TaskForce (IOTF) cutoffs to define overweight and obesity were used. In the total sample we found 20.3% of overweight children and 11.3% of obese children. These results indicate a prevalence of overweight/obesity of 31.5%. Girls presented higher percentages of overweight than boys except at age 7.5. Girls also showed a higher percentages of obesity than boys except at age 9. From 1970 to 1992 and 1992 to 2002, height, weight, and BMI increased at different velocities: weight increased faster than height, and, consequently, BMI increased more in the last period than in the first one, leading to an increase in obesity values. Compared to published data by IOTF on other European countries, who applied the same methods to define overweight and obesity, Portuguese children showed the second-highest mean values in overweight/obesity. Italy showed the highest values (36%). The present study shows a very high prevalence of overweight/obesity (31.5%) in Portuguese children compared to other European countries. Portugal followed the trend of other Mediterranean countries like Spain (30%), Greece (31%), and Italy (36%). These high values require a national intervention program to control childhood obesity.     

Overweight and obesity in affluent school children of Punjab

In the present cross-sectional study, an attempt has been made to report the prevalence of overweight and obesity in school-going children of the affluent families of Punjab. A total of 1000 children (490 boys and 510 girls) were measured for height and weight. Overweight and obesity were assessed using age and sex-specific body mass index (BMI) cut-off points. In the present study, 12.24% boys and 14.31% girls were overweight, and 5.92% boys and 6.27% girls were obese. The prevalence of overweight and obesity among the affluent school children of Punjab was as high or higher as in some developed countries.     

International definitions of overweight and obesity for children: a lasting solution?

Background : Definitions of overweight and obesity for children were published in 2000, derived by averaging the centiles of six countries equivalent to body mass index (BMI) at age 18 years of 25 and 30. For use in the UK it is unclear whether these present an advantage over equivalent definitions based on UK data. Aim : To compare the recently published international cut-off points for overweight and obesity in children with alternative cut-off points based on the UK 1990 reference data. Subjects and methods : Around 6000 white children aged 4-11 years from primary schools in 22 areas in England were measured in two cross-sectional surveys, in 1984 and 1994. Measurements included height and weight, from which BMI was calculated. Each child was classified as overweight or obese according to each cut-off point. Results : The proposed international cut-off points exaggerate the difference in prevalence of overweight and obesity between English boys and girls in comparison to comparable measures based on UK data by up to 7%, and are not compatible with the UK reference charts for BMI. Using proposed UK cut-off points the prevalence of overweight in boys was 10.2% in 1984, rising to 13.8% in 1994, compared to 5.4 to 9.0% using the international definition. Conclusion : The limitations of the international definitions, due to averaging data from different countries and the choice of reference age, need to be known. The UK cut-off points here presented are compatible with the current UK reference curves.     

International definitions of overweight and obesity for children: a lasting solution?

BACKGROUND: Definitions of overweight and obesity for children were published in 2000, derived by averaging the centiles of six countries equivalent to body mass index (BMI) at age 18 years of 25 and 30. For use in the UK it is unclear whether these present an advantage over equivalent definitions based on UK data. AIM: To compare the recently published international cut-off points for overweight and obesity in children with alternative cut-off points based on the UK 1990 reference data. SUBJECTS AND METHODS: Around 6000 white children aged 4-11 years from primary schools in 22 areas in England were measured in two cross-sectional surveys, in 1984 and 1994. Measurements included height and weight, from which BMI was calculated. Each child was classified as overweight or obese according to each cut-off point. RESULTS: The proposed international cut-off points exaggerate the difference in prevalence of overweight and obesity between English boys and girls in comparison to comparable measures based on UK data by up to 7%, and are not compatible with the UK reference charts for BMI. Using proposed UK cut-off points the prevalence of overweight in boys was 10.2% in 1984, rising to 13.8% in 1994, compared to 5.4 to 9.0% using the international definition. CONCLUSION: The limitations of the international definitions, due to averaging data from different countries and the choice of reference age, need to be known. The UK cut-off points here presented are compatible with the current UK reference curves.     

At what age do normal weight Canadian children become overweight adults? Differences according to sex and metric

Background: The prevalence of overweight and obesity doubles between adolescence and young adulthood; however, the exact age, and appropriate metric to use to identify when overweight develops is still debated.

Aim: To examine the age of onset of overweight by sex and four metrics: body mass index (BMI), fat mass (%FM), waist circumference (WC) and waist-to-height ratio (WHtR).

Subjects and methods: Between 1991 and 2017, serial measures of body composition were taken on 237 (108 males) individuals (aged 8–40?years of age). Hierarchical random effects models were used to develop growth curves. Curves were compared to BMI, %FM and WC overweight age- and sex-specific cut-points.

Results: In males, the BMI growth curve crossed the cut-point at 22.0?years, compared to 23.5 and 26.5?years for WHtR and %FM, respectively; WC cut-off was not reached until 36?years. In females, the BMI growth curve crossed the overweight cut-point at 21.5?years, compared to 14.2?years for %FM and 21.9 and 27.5?years for WC and WHtR, respectively.

Conclusion: In summary, overweight onset occurs during young adulthood with the exception of WC in males. BMI in males and %FM in females were the metrics identifying overweight the earliest.     

Relationship of single measures of cardiorespiratory fitness and obesity in young schoolchildren.

The purpose of this study was to examine differences of cardiorespiratory fitness (CRF) among weight groups, and the associations of CRF with obesity (body mass index) in a sample of young children. Anthropometric data (height, body mass, and two skinfolds) were collected for 255 healthy children aged 8-10 years (127 boys and 128 girls). Children were placed in three groups (nonobese, overweight, and obese), using body mass index (BMI) sex- and age-specific cutoff points. Cardiorespiratory fitness was assessed with a 1-mile run test. Participants were separated into two groups: fit and unfit, according to age- and sex-specific scores defined by FITNESSGRAM. The prevalence of overweight (30.5% vs. 29.1%) and obesity (13.2% vs. 12.6%) was at the same magnitude for boys and girls. Overall, 109 children (42.7%) were overweight and obese. Sums of skinfolds, weight, and BMI were significantly lower (P < 0.05) in lean boys and girls compared to their overweight and obese counterparts. Regarding height, no significant differences were found in girls, while in boys, significant differences were only found between nonobese and obese. No differences were found in obesity groups according to CRF in boys, while significant differences were found for girls (P < 0.01). Logistic regression analysis showed that girls who were overweight (odds ratio = 0.05, P = 0.000) or obese (odds ratio = 0.09, P = 0.001) were likely to be unfit. No significant results were found in boys. Overweight and obese children presented higher sums of skinfolds and weight compared with their lean counterparts. Increased BMI was significantly associated with lower CRF in girls. Thus, our data clearly showed potential gender differences of body composition in CRF, which would be of great clinical significance. Therefore, even at young ages, at least for girls, the beneficial impact of low BMI values on CRF is shown with important clinical and public health implications.     

Diagnostic Performance of Body Mass Index Using the Western Pacific Regional Office of World Health Organization Reference Standards for Body Fat Percentage

Associations between body mass index (BMI), body fat percentage (BF%), and health risks differ between Asian and European populations. BMI is commonly used to diagnose obesity; however, its accuracy in detecting adiposity in Koreans is unknown. The present cross-sectional study aimed at assessing the accuracy of BMI in determining BF%-defined obesity in 6,017 subjects (age 20-69 yr, 43.6% men) from the 2009 Korean National Health and Nutrition Examination Survey. We assessed the diagnostic performance of BMI using the Western Pacific Regional Office of World Health Organization reference standard for BF%-defined obesity by sex and age and identified the optimal BMI cut-off for BF%-defined obesity using receiver operating characteristic curve analysis. BMI-defined obesity (≥25 kg/m²) was observed in 38.7% of men and 28.1% of women, with a high specificity (89%, men; 84%, women) but poor sensitivity (56%, men; 72% women) for BF%-defined obesity (25.2%, men; 31.1%, women). The optimal BMI cut-off (24.2 kg/m²) had 78% sensitivity and 71% specificity. BMI demonstrated limited diagnostic accuracy for adiposity in Korea. There was a -1.3 kg/m² difference in optimal BMI cut-offs between Korea and America, smaller than the 5-unit difference between the Western Pacific Regional Office and global World Health Organization obesity criteria.

Graphical Abstract

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