Body Mass Index Cut-off Points Research Articles

Body mass index distribution affects discrepancies in weight classifications in children

The aim of the present study was to investigate the effect of body mass index (BMI) distribution, ethnicity and age at menarche on the consistency in the prevalence of underweight and overweight defined by the Centers for Disease Control and Prevention (CDC) and the International Obesity Task Force (IOTF) cut-off points in 2-17-year-old Chinese and US children. Data from the China Health and Nutrition Survey (CHNS) 1991 (n= 3895), CHNS 2004 (n= 1902), and the National Health and Nutrition Examination Survey (NHANES) 2003-2004 (n= 3344) were used to define the prevalence of underweight and overweight using the CDC and IOTF BMI cut-off points. An upward shift in the BMI distribution was observed from the CHNS 1991 to CHNS 2004, and between the CHNS and NHANES 2004. The prevalence of underweight defined by the IOTF cut-off points was higher than that obtained using the CDC cut-off points; absolute differences between IOTF and CDC classifiers were 7%, 5%, and 2% in boys, and 12%, 11%, and 4% in girls in the CHNS 1991, CHNS 2004, and NHANES 2004, respectively. There was a greater consistency in the prevalence of overweight. The consistency of the two classification systems increased with the higher BMI distribution and was not affected significantly by ethnicity or age at menarche. The BMI distribution of a population can affect the classification of childhood underweight and overweight differentially as defined by the CDC and IOTF cut-off points, and thus should be considered in the interpretation of results in clinical and population settings.

Cut-off points of waist circumference and body mass index for detecting diabetes, hypercholesterolemia and hypertension according to National Non-Communicable Disease Risk Factors Surveillance in Iran.

IntroductionThe cut-off points of waist circumference and body mass index (BMI) are varied according to different races. There is a dearth of information on these indices especially in Iranian adults. We sought to estimate the cut-off points of waist circumference and BMI for detecting diabetes, hypercholesterolemia, and hypertension.Material and methodsThe data were gathered by the First Iranian Non-Communicable Disease Survey in 2005. In total, 70,981 participants between 25 and 64 years of old were selected via random multistage cluster sampling. Receiver operating characteristic curves were used to show the cut-off points of waist circumference and BMI for detecting diabetes, hypercholesterolemia, and hypertension. The maximum value the sum of sensitivity and specificity indicated the cut-off point.ResultsThe cut-off points of waist circumference according to maximum sum of sensitivity and specificity for detecting hypertension, diabetes, and hypercholesterolemia in men were 89.7 cm, 89.4 cm and 88.2 cm and in women were 93.9 cm, 96.2 cm and 90 cm respectively. The cut-off points of BMI according to maximum sum of sensitivity and specificity for detecting hypertension, diabetes, and hypercholesterolemia in men were 25.7 kg/m2, 24.8 kg/m2 and 24 kg/m2 and in women were 26.9 kg/m2, 26.3 kg/m2 and 26.1 kg/m2 respectively.ConclusionsThis was a population-based study on a huge sample on the basis of a national survey. The Iranian BMI was different from the values suggested by the WHO. The waist circumference in Iranian women was higher than that in men.

The Significance of Measuring Body Fat Percentage Determined by Bioelectrical Impedance Analysis for Detecting Subjects With Cardiovascular Disease Risk Factors

Body fat percentage (BF%) determined by bioelectrical impedance analysis is widely used at home and in medical check-ups. However, the clinical significance of measuring BF% has not been studied in detail. A cross-sectional study was carried out on a cohort of 10,774 middle-aged Japanese men who had undergone an annual check-up in 2008. Cut-off points were evaluated for body mass index (BMI), waist circumference (WC), and BF% for detecting participants with cardiovascular disease (CVD) risk factors (diabetes mellitus, hypertension, dyslipidemia), and effectiveness compared for each marker's cut-off point. Additionally, the effects of smoking on cut-off points were evaluated. The cut-off points of BMI, WC, and BF% for detecting participants with 1 or more CVD risk factors were 22.7kg/m(2), 81.4cm, and 20.3%, respectively. The cut-off points of BF% for 1 or more CVD risk factors classified 3.43% more subjects into correct categories than those of BMI (P<0.001). The cut-off points of BMI, WC, and BF% for detecting individuals with 3 CVD risk factors in current smokers were 24.9kg/m(2), 87.8cm, and 23.7%, while those in non-smokers were 23.3kg/m(2), 83.9cm, and 22.3%, respectively. BF% could be more effective in detecting individuals with early stage CVD risk accumulation than BMI. The cut-off points for current smokers were lower than those for non-smokers in all markers.

Physical fitness is inversely related with body mass index and body fat percentage in soccer players aged 16-18 years

Adolescents are at increased risk for the development of obesity, while sport has been suggested as an effective means against adolescent obesity. The objectives of this study were to examine (a) the prevalence of overweight/obesity, (b) the relationship between body mass index and body fat percentage, and (c) the association between body mass index, body fat and physical fitness in soccer players aged 16-18 yr. Members (n=109, aged 17.0 +/- 0.5 yr) of competitive soccer clubs were examined for physical and physiological characteristics. Based on international body mass index cut-off points, 18.3% (n=20) of participants were classified as overweight. Body mass index was highly correlated with body fat percentage (r=0.70, p<0.001). Body fat percentage was in inverse relationship with aerobic power (r=-0.21, p=0.029), maximal anaerobic power (r=-0.20, p=0.044) and local muscular endurance (r=-0.39, p<0.001), while corresponding values of body mass index were non-significant (r=-0.05, p=0.614: r=0.03, p=0.771: r=-0.12, p=0.220, respectively). However, both body fat percentage and body mass index were inversely related with fatigue index of Wingate anaerobic test (r=-0.26, p=0.009; r=-0.29, p=0.003, respectively). The strong relationship between body mass index and body fat percentage suggest the further use of body mass index in adolescent soccer players. The findings confirmed previous observations on general population about the negative effect of overweight and fatness on physical fitness. The prevalence of overweight among participants was similar with what is observed in general population. Therefore, sport participation cannot guarantee physiological body mass and body composition, and it is necessary to prescribe exercise targeting body mass and fat control.

The body mass index (BMI) as a public health tool to predict metabolic syndrome

Objective: To analyze the body mass index (BMI) as an indicator of metabolic alterations, including the metabolic syndrome (MetS), at both individual level and public health level. Method: We recruited 3683 undergraduate students (17 - 24 years old) from México City identifying metabolic alterations, including the MetS, and comparing its prevalence by BMI ranges. We applied a sensitivity analysis to define BMI optimal cut-off point values. Results: We found 14.6% of MetS prevalence with a BMI average of 24.2%, and 34.5% of overweight prevalence (BMI ≥ 25). A BMI cut-off point value of 22.5 is suggested as an upper limit of a normal weight condition, only for public health purpose; while at individual level the BMI cut-off point of 25 was corroborated as the upper limit for a normal weight condition. A public health tool to estimate the MetS prevalence based on BMI percentages is proposed, and a study case is presented. Conclusion: BMI fails predicting at individual level both, healthy condition or metabolic alterations, when values are lower than 25. At population level, the BMI is a valuable public health tool to estimate MetS prevalence: based on the prevalence of MetS by BMI ranges of a sample of the population.

References of anthropometric indices of central obesity and metabolic syndrome in Jordanian men and women

To set references and evaluate the associations between the predictive powers of the anthropometric indices of obesity, particularly central obesity, including body mass index (BMI), waist circumference (WC), waist to hip ratio (WHpR) and waist to height ratio (WHtR), and the risk factor accumulations of ≥ 2 of the components of the metabolic syndrome (MS) in a group of Jordanian men and women. Five hundreds subjects were randomly selected from among the visitors attending several family clinics in Amman. Obesity was assessed using BMI, WC, WHpR and WHtR anthropometric indices. MS risk factors as defined by the International Diabetes Federation were determined. Receiver operating characteristic curve (ROC) analysis was used to determine the predictive powers and the cut off points of each index associated with increased MS risk. There were 212 men and 288 women with age ranged 20-85 years. Optimal cut off points of BMI, WC, WHpR for MS diagnosis in men were 28.4 kg/m(2), 97.8 cm and 0.89, respectively. In women, these were 30.3 kg/m(2), 95.6 cm and 0.84, respectively. WHtR was 0.61 in both genders. Area under the curve (AUC) of ROC analysis for identifying of MS (≥ 2 risk factors) was the highest for WHpR (AUC=0.71), followed by WHtR (AUC=0.67), WC (AUC=0.64) and BMI (AUC=0.59) in men; whereas in women WHpR, WHtR and WC were almost equal (AUC=0.76, 0.75 and 0.74, respectively), followed by BMI (AUC=0.67). Correlation coefficients (r) between WHpR and MS risk factors were the strongest among the other obesity indices, followed by WC and WHtR. WHpR correlated significantly with FBG (r=0.27, p<0.01), systolic blood pressure (r=0.20, p<0.01), TGs (r=0.24, p<0.01) and HDL-C (r=-0.39, p<0.01). The respective r-values between WC and WHtR and each MS risk factors were: FBG (r=0.15, p<0.001 or r=0.13, p<0.01), systolic blood pressure (r=0.16, p<0.01 or r=0.11, p<0.05), TGs (r=0.20, p<0.01 or r=0.14, p<0.01) and HDL-C (r=-0.25, p<0.01 or r=-0.11, p<0.01). This study showed that BMI tended to be the weakest index for identifying MS risk factors in both sexes. WHpR exhibited the best predictive index for MS, particularly in men. Almost similar predictive powers of WHtR, WHpR and WC for identifying MS risk factors were seen in women. WHtR had the highest sensitivity for MS diagnosis among obesity indices in men and its boundary value was the same for both men and women. These cut off values of obesity particularly waist circumference should be advocated and used in Arab Jordanians until larger cross sectional studies shows different results.

Overweight, obesity and underweight in rural black South African children

Background: The objective was to estimate the prevalence of overweight, obesity and underweight conditions among rural black children in South Africa. A cross-sectional study was undertaken. The setting was Mankweng and Toronto, both rural settlements in Capricorn district, Limpopo province, South Africa.Participants were 1172 school children (541 boys and 631 girls) aged 10–16 years.Method: The prevalence of overweight, obesity and underweight was examined, using the Centers for Disease Control and Prevention (CDC) body mass index (BMI) cut-off points. Height and body weight were measured using standard techniques. Results were analysed with student t-test statistics, with probability level set at p-value ≤ 0.05.Results: The percentage of children who were at risk of overweight were higher in girls (11%) than boys (9.1%), whereas obesity occurred more among the boys (5.5%), compared with the girls (4.4%). Applying the CDC cut-off points of 5th < percentile to define underweight, 25 (4.6%) and 35 (5.2%) of boys and girls respectively were underweight.Conclusion: Similar to previous studies, this study indicates that overweight and obesity are high among South African children, even in rural settings. The study also demonstrates that underweight is prevalent among the sampled children. This supports the notion of a double burden of disease in developing countries.

The normal range of body mass index with high body fat percentage among male residents of Lucknow city in north India.

Background & objectives:Several studies have raised the suspicion that the body mass index (BMI) cut-off for overweight as defined by the WHO may not adequately reflect the actual overweight status. The present study looked at the relationship between BMI and body fat per cent (BF %) / health risks (hypertension and type 2 diabetes) in male residents of Lucknow city, north India to evaluate the validity of BMI cut-off points for overweight.Methods:One thousand one hundred and eleven male volunteer subjects (18-69 yr) who participated in different programmes organized by the Institute during 2005 to 2008 were included in the study. BF% was measured using commercially available digital weight scale incorporating bioelectrical impedance (BI) analyzer. The proposed cut-off for BMI based on BF % was calculated using receiver operating characteristics (ROC) curve analysis.Results:Forty four per cent subjects showed higher BF % (>25%) with BMI range (24-24.99 kg/m2). Sensitivity and specificity at BMI cut-off at 24.5 kg/m3 were 83.2 and 77.5, respectively. Sensitivity at BMI cut-off >25 kg/m2 was reduced by 5 per cent and specificity increased by 4.6 per cent when compared to 24.5 cut-off.Interpretation & conclusions:The study subjects showed higher body fat percentage and risk factors like hypertension and type 2 diabetes at normal BMI range proposed by the WHO. The cut-off for BMI was proposed to be 24.5 kg/m2 for our study population. If overweight is regarded as an excess of body fat and not as an excess of weight (increased BMI), the cut-off points for overweight based on BMI would need to be lowered. However, the confidence of estimate of the BMI cut-off in the present study may be considered with the limitations of BI analysis studies.

Parental work schedules and child overweight and obesity

Studies in school-age children have consistently shown a positive association between maternal paid work hours and child obesity. However, there is conflicting evidence about the impact of maternal work hours scheduled at nonstandard times (for example, evenings, nights or weekends), and no previous examination of paternal work schedules and child weight. We examined the associations between maternal, paternal and combined parental paid work schedules and overweight/obesity in children at age 9 years. Data were analysed from the most recent follow-up of 9-year-old children (n=434) in an Australian birth cohort study. Children were measured and classified as overweight/obese using the International Obesity Taskforce body mass index cutoff points. Current working conditions of parents were obtained from a structured interview with the primary caregiver. Logistic regression analyses were used to investigate the effect of parental work schedules on child overweight/obesity with adjustment for a range of sociodemographic and household factors associated with parental employment and child weight. At 9 years of age, 99 children (22.8%) were overweight or obese. When parental work schedules were examined separately, child overweight/obesity was significantly associated with paternal nonstandard work schedules (adjusted odds ratio (OR) 1.97, 95% confidence interval (CI) 1.08-3.61). There was no association with any type of maternal work schedule. We also found an association between child overweight/obesity and circumstances in which both parents worked nonstandard schedules; however, this was of borderline statistical significance in the adjusted models (adjusted OR 2.26, 95% CI 0.99-5.16). Work hours scheduled at nonstandard times, when worked by the father or both parents, were associated with child overweight and obesity. These findings indicate the potential importance of fathers' paid work arrangements for child overweight/obesity, which until recently has largely been ignored.

Adiposity rather than BMI determines metabolic risk

Background and aimThere is increasing evidence suggesting that WHO body mass index (BMI) cut-off values are outdated and should not be applied to different population. To overcome misclassifications, direct measurements of percentage body fat (PBF) would be a better tool for preobesity and obesity diagnosis. The aim of this study was to analyze the body composition in a adult population in Centre-South of Italy, by age and gender, and to verify the accordance between BMI and PBF cut-off points for health status classification. MethodsThe total subject pool cover a total of 4408 participants adults. A completed screening of anthropometry and body composition by Dual X-ray Absorptiometry, (DXA) was assessed on 3.258 subjects. ResultsDistributions and quantitative reliable estimates of PBF, total body fat and lean, according to gender and age are provided. The prevalence of “at risk” subjects (preobese and obese) was 69% and 85%, for men and women respectively, according to PBF cut-off points. The agreement of BMI and PBF categories resulted low for the total and male population, even scarce for female population (all P≤0.001). The false negative classification of BMI was stronger for women than men and for younger than older subjects. ConclusionsScreening for adiposity in subjects with a normal BMI could better identify those at higher risk for cardiometabolic disturbances and cardiovascular mortality. The herein used cut-offs points of PBF, by age and gender, may provide a useful reference in clinical settings and public health services, in particular for the Italian Caucasian population.

Defining obesity cut-off points for migrant South Asians.

BackgroundBody mass index (BMI) and waist circumference (WC) are used to define cardiovascular and type 2 diabetes risk. We aimed to derive appropriate BMI and WC obesity cut-off points in a migrant South Asian population.Methods4688 White Europeans and 1333 South Asians resident in the UK aged 40–75 years inclusive were screened for type 2 diabetes. Principal components analysis was used to derive a glycaemia, lipid, and a blood pressure factor. Regression models for each factor, adjusted for age and stratified by sex, were used to identify BMI and WC cut-off points in South Asians that correspond to those defined for White Europeans.FindingsFor South Asian males, derived BMI obesity cut-off points equivalent to 30.0 kg/m2 in White Europeans were 22.6 kg/m2 (95% Confidence Interval (95% CI) 20.7 kg/m2 to 24.5 kg/m2) for the glycaemia factor, 26.0 kg/m2 (95% CI 24.7 kg/m2 to 27.3 kg/m2) for the lipid factor, and 28.4 kg/m2 (95% CI 26.5 kg/m2 to 30.4 kg/m2) for the blood pressure factor. For WC, derived cut-off points for South Asian males equivalent to 102 cm in White Europeans were 83.8 cm (95% CI 79.3 cm to 88.2 cm) for the glycaemia factor, 91.4 cm (95% CI 86.9 cm to 95.8 cm) for the lipid factor, and 99.3 cm (95% CI 93.3 cm to 105.2 cm) for the blood pressure factor. Lower ethnicity cut-off points were seen for females for both BMI and WC.ConclusionsSubstantially lower obesity cut-off points are needed in South Asians to detect an equivalent level of dysglycemia and dyslipidemia as observed in White Europeans. South Asian ethnicity could be considered as a similar level of risk as obesity (in White Europeans) for the development of type 2 diabetes.

Gross motor skill performance in a sample of overweight and non-overweight preschool children

The aim of the study was to examine the gross motor skill performance of overweight and non-overweight preschool children from South of Italy, and to investigate possible differences by gender. Participants were 38 boys and 42 girls (4.5 ± 0.5 yr) categorized as overweight (n = 38) and non-overweight (n = 42), according to the IOTF body mass index (BMI) cut-off points. The Test of Gross Motor Development was used to assess seven locomotor skills (run, gallop, hop, leap, horizontal jump, skip and slide) and five object-control skills (two-hand strike, stationary bounce, catch, kick and overhand throw). The raw, standard and percentile scores and the Gross Motor Development Quotient (GMDQ) were calculated for each participant. ANOVA 2 (gender) x 2 (group) was conducted on the subtest standard scores and the GMDQ. No differences in performance were found between boys and girls on the subscale standard scores and the GMDQ. Significant main effects (p < 0.001) were reported for group on the GMDQ, and the standard scores for locomotor and object-control skills, with overweight children reporting lower movement competence than their counterparts. Pearson's correlations revealed relationships (p < 0.001) between BMI and locomotor (r = -0.54) and object-control (r = 20.48) skills, and between BMI and GMDQ (r = 20.54). Findings indicate that childhood obesity might have adverse effects on gross motor development. Overweight participants showed poorer performance on locomotor and object-control tasks than their non-overweight peers. Interventions to promote physical activity in overweight children should be directed towards achieving a healthy weight and motor skill improvement.

Comparison of Anthropometric Indices in Predicting Metabolic Syndrome Components in Children

The International Diabetes Federation (IDF) defines metabolic syndrome among children. In addition to the abdominal obesity (waist circumference ≥90 percentile of locally representative sample), the risk criteria for metabolic syndrome includes elevated blood pressure, hypertriglyceridemia, low high-density lipoprotein cholesterol (HDL-C) levels, and elevated fasting glucose. In this study, we compared the association of anthropometric indices with metabolic syndrome risk criteria in 9-year-old children. A cross-sectional study of 9-year-old children (n=1,194) was performed in 2007-2008. Using the international cutoff points and percentiles, we determined subjects with elevated blood pressure, hypertriglyceridemia (≥90 percentile), low HDL-C (≤ 10 percentile), and elevated fasting glucose (≥100 mg/dL). We compared several anthropometric indices [triceps skin-fold thickness (SFT), waist circumference, hip circumference, waist-to-hip ratio, body mass index (BMI) and waist-to-height ratio] and their association with metabolic syndrome risk criteria other than waist circumference among 9-year-old children. Metabolic syndrome risk criteria were commonly observed among 9-year-old children: 244 students (20.4%) had hypertriglyceridemia and/or low HDL-C, 362 students (30.3%) had elevated blood pressure, and 254 (21.3%) students were overweight or obese. Among covariates of SFT, BMI, waist circumference, waist-to-hip, or waist-to-height ratio categories, the BMI category was the only significant predictor of having two or more metabolic syndrome risk variables [odds ratio (OR)=3.5, 95% confidence interval (CI) 1.69-7.41, P=0.001 for boys and OR=4.7, 95% CI 1.61-13.55, P=0.005 for girls]. Assessing anthropometric indices is crucial for early detection and prevention of metabolic syndrome among children and adolescents. Age- and sex-specific cutoff points of BMI can be used to screen for the metabolic syndrome and related risk criteria among 9-year-old children.

Gross motor coordination in relation to weight status and age in 5- to 12-year-old boys and girls: A cross-sectional study

The purpose of this study was to investigate differences in gross motor coordination in healthy-weight, overweight, and obese children of different ages. Using a cross-sectional design, data were collected in 954 Flemish primary school children (500 girls, 454 boys) stratified in consecutive age groups (5-7 years, 8-9 years, 10-12 years). Weight status (healthy-weight, overweight, obese) was defined according to the International Obesity Task Force body mass index (BMI) cut-off points for children. Gross motor coordination was assessed by means of the Körperkoordinationstest für Kinder (KTK). Childhood overweight and particularly obesity were found to result in poorer KTK performances (p < 0.001), with the most apparent effect of BMI on items requiring physical properties next to dynamic body coordination. Expressed as an age-related Motor Quotient (MQ), overall KTK performance was featured by a BMI × AGE interaction (p < 0.01). Healthy-weight children displayed similar MQs across age groups (p = 0.999). Overweight and obese children in the 10-12-year-old group showed significantly poorer motor coordination performance compared with the corresponding 5-7-year-old group (p < 0.01). Less than 20% of the healthy-weight participants was identified as being motor impaired, while that proportion increased to 43.3% and up to 70.8% in children with overweight and obesity, respectively. Results indicate that BMI-related differences in gross motor coordination were more pronounced as children belonged to an older age group. Although this outcome needs to be confirmed in future longitudinal research, it emphasizes the need of an early focus on motor skill improvement to encourage overweight and obese children to be physically active.

Differences in Heart Rate Recovery Between Normal and Obese Boys After Shuttle Run Test

Heart rate recovery (HRR) is considered a valid index of training level and cardiovascular system health. A recent study showed a positive relationship between the HRR and body mass index (BMI) in physically active children, suggesting a possible link between healthy body weight and faster HRR. However there is a lack of knowledge about this association on normal weight and obese children. PURPOSE: To compare the HRR responses between normal weight boys (NB) and obese boys (OB) after maximal multistage 20 m Shuttle Run Test (20 MST). METHODS: The sample included 68 boys, aged between 6 to 9 years, NB (n= 52; weight=28.81±5.11 kg; height 132.05±7.85 cm) and OB (n= 16; weight=44.52±9.14 kg; height 135.38±8.97 cm). Age-specific BMI cut-off points were used to classify normal weight and obesity. 20 MST was performed according to the procedures described in EUROFIT battery. HR was recorded during 20 MST, and after 5 min recovery period (POLAR FS2c, Polar Electro Inc., Finland). HR was integrated each minute. Independent Sample T Test was performed to compare values between NB and OB. RESULTS: We did not found significant differences on performances (number of stages) at final of the 20 MST between NB and OB (2.81 vs. 1.93, p>0.05). However, maximal HR of the test was significantly different (183.17±18.05 beats/min vs. 195±13.03 beats/min, p<0.05). Also, HRR was higher in OB after 1st minute (130.38±22.06 BPM vs. 144.07±22.88 BPM, p< 0.05), 2nd minute (113.52±16.20 BPM vs. 129.21±16.47 BPM, p= 0.05)as well as in the third minute of the recovery period (108.42±13.92 BPM vs. 118.07±15.48 BPM, p= 0.030). We did not find differences after the 4th and 5th minutes, although HRR was always lower in NB than in OB. CONCLUSIONS: The main finding of this study was that obesity influences HRR on children, in spite of the fact that their capacity to perform the 20 MST is the same as the normal weight boys. Recommending aerobic exercise to obese children not only could reduce their fat mass but also could lead to a better post effort recovery. The implications of these results for youth health remain to be studied.

Physical Activity Recommendations in Relation to Weight Status for Hong Kong Children Using ROC Analysis

There is a lack of practical physical activity (PA) recommendations for children in Hong Kong compared with western countries, especially in relation to health risk factors. PURPOSE: To determine accelerometer-derived PA recommendations in relation to weight status for Hong Kong children. METHODS: A total of 486 children aged 6-10 years were instructed to wear an ActiGraph GT3X accelerometer for 8 consecutive days to determine their PA level. Among them, 314 participants (162 boys) who recorded sufficient accelerometer data for at least 3 weekdays and 1 weekend day were included in the final analyses. Average time (minutes/day) spent on moderate to vigorous PA (MVPA) was calculated based on Freedson's age-specific cut-off counts. Body weight and height were measured to calculate the body mass index (BMI). Overweight and obesity were classified according to the age- and gender-specific BMI cut-off points. Data were collected as part of a longitudinal study Understanding Children's Activity and Nutrition (UCAN). Comparisons of MVPA time between weight status were made using independent-samples T test. Receiver operating characteristic (ROC) curves were used to identify the optimal cut point of minutes in MVPA to predict overweight. The cut point was chosen on the basis that it maximized sensitivity and specificity (with the Youden index maximized). RESULTS: 28% of the children were classified as overweight or obese. PA level between overweight and nonoverweight children was similar (MVPA: 122 ± 45 vs. 128 ± 46 minutes/day, NS). The area under the ROC curve (AUC) was not significantly different to 0.5 among boys and girls respectively. Across all participants, the AUC was 0.535 (P<0.05) and the cut point to optimally discriminate between overweight and non-overweight children was 161 minutes/day (Youden index = 0.098). CONCLUSION: The results suggested that 161 minutes/day MVPA is recommended for children aged 6-10 years to lower the risk of being overweight, which is higher than the general recommendations in western countries.

Periodontitis and Obesity: A Study of the Fourth Korean National Health and Nutrition Examination Survey

The present study aims to determine whether there is an association between periodontitis and obesity among Korean adults who participated in the Fourth Korean National Health and Nutrition Examination Survey (KNHANES). In 2007, 4,246 subjects, >19 years of age, who participated in the KNHANES (a cross-sectional survey conducted by the Korea Centers for Disease Control and Prevention) were selected for analysis. Participants underwent a periodontal examination and anthropometric measurements, and were asked to complete a questionnaire about their socioeconomic status and overall health status. Body mass index (BMI) and waist circumference (WC) were used as measures of overall body fat and upper body fat. Standard BMI and WC cutoff points were used, as established by the World Health Organization and the Korean Society for the Study of Obesity. Periodontal status was assessed by Community Periodontal Index and periodontitis was defined as ≥ "code 3." Multivariate logistic regression analyses were carried out, adjusting for the following variables: sex; age; household income; bedtime toothbrushing habits; use of dental floss; use of an interproximal toothbrush; presence of active tooth decay; the number of decayed, missing, or filled permanent teeth; diabetes mellitus; and present smoking status. In multivariate logistic regression analysis, there was no association between BMI and periodontitis. Obese people with BMI ≥25 had an adjusted odds ratio of 0.991 (0.806 to 1.220) for having periodontitis. But we found a significant association between abdominal obesity and periodontitis. After adjusting for all covariates, the adjusted odds ratio for periodontitis was 1.358 (confidence interval 1.003 to 1.839) for obese subjects. A high WC seems to be associated with periodontitis, whereas BMI does not. This finding shows that abdominal obesity is significantly correlated with periodontitis.

Problems in the Japanese criteria for metabolic syndrome.

Dear Editor, Ogawa et al. studied the cut-off point of waist circumference (WC) for the clustering of two or more metabolic risk factors among the three non-WC components of Japanese metabolic syndrome (JMetS) and proposed to amend JMetS regarding the cut-off point of WC for women1. However, the most dangerous drawback of JMetS criteria is that it makes abdominal obesity a necessary component. Other problems of JMetS criteria are the cut-off point of impaired fasting glucose, the unnecessary combination of two components (hypertriglyceridemia and hypo-high-density lipoprotein cholesterolemia into one component) and the cut-off point of high-density lipoprotein cholesterol for women. In 2009, a worldwide consensus statement2 for the criteria of metabolic syndrome (MetS) was jointly issued by the International Diabetes Federation (IDF) Task Force on Epidemiology and Prevention; National Heart, Lung, and Blood Institute (NHLBI); American Heart Association (AHA); World Heart Federation; International Atherosclerosis Society; and International Association for the Study of Obesity. In this statement, the revised National Cholesterol Education Program (NCEP) criteria (AHA/NHLBI criteria) where abdominal obesity is not a necessary component was adopted as the worldwide definition of MetS. The 2005 IDF criteria of MetS where abdominal obesity is a necessary component were withdrawn by the IDF itself. However, the cut-off points of WC could not be determined for any ethnic groups2. In 2007, the Association for Weight Management and Obesity Prevention, the Obesity Society, the American Society for Nutrition, and the American Diabetes Association issued a consensus statement regarding WC, where they stated that there is not yet a compelling body of evidence showing that WC provides clinically meaningful information that is independent of well-known cardiometabolic risk factors3. Although the cut-off points of WC were controversial, those of body mass index (BMI) were widely accepted as 25 kg/m2 for overweight and 30 kg/m2 for obesity. We compared BMI, WC and percentage of body fat as markers for the clustering of metabolic risk factors in 2444 Japanese men and 1442 Japanese women, and found no significant difference among these three obesity parameters as a marker of metabolic risk clustering4. Therefore, both a BMI cut-off point of 25 kg/m2 and a WC cutoff point of 85 cm for men and 80 cm for women might be appropriate for a cut-off point of an obesity component of MetS. However, the most important point is that obesity is not a necessary component of MetS. It was pointed out by NIPPON DATA90 that the definition of MetS where obesity is a necessary component is dangerous, because normal-weight individuals have a high mortality risk and are more prevalent than obese or overweight subjects in Japan. A Japan Public Health Center-based (JPHC) study also concluded that the MetS definition requiring obesity or overweight as a necessary component might not necessarily identify normal-weight individuals who have a high mortality risk and are more prevalent than subjects with JMetS, and suggested that MetS based on the AHA/NHLBI criteria predicts cardiovascular disease better than MetS based on the 2005 IDF criteria where abdominal obesity is a necessary component.

Relationship of serum retinol-binding protein 4 with weight status and lipid profile among Korean children and adults

Although some studies have suggested that retinol-binding protein 4 (RBP4), a fat-derived adipokine, is positively related to overweight and obesity-related disorders, these claims have been disputed. This study investigated relationships between RBP4 level and weight status and metabolic disorders in a Korean population including confounding factors, age and gender. From 2005 to 2007, we recruited 570 children and 241 of their parents living in Korean urban areas. We analyzed anthropometrical parameters, blood pressure, lipid profiles, and levels of serum glucose, insulin, leptin and RBP4, and estimated dietary intake based on a self-reported 3-day food diary. Levels of RBP4 were high for men (226.2 μg/ml), mid-range among women (143.2 μg/ml) and low among boys and girls (boys 71.4, girls 66.9 μg/ml). After adjusting for age, gender differences among adults were consistently maintained (P<0.0001), and gender differences among children were detected minimally (P=0.05). On the basis of Cole's body mass index cutoff points, the prevalence of overweight among children was 19.3%. The prevalence among adults was 32.0%, based on World Health Organization criteria. Overweight children had higher RBP4 concentrations than normal. Overweight women had higher RBP4 levels than those of normal weight. Higher RBP4 levels were observed among overweight men, but the results were not statistically significant. Triglyceride (TG) levels were significantly correlated with RBP4 in all groups. Our results indicate that RBP4 concentrations in a Korean population varied with age, gender and overweight status. TG levels could be strongly correlated with RBP4 concentration.

Low Physical Activity Is a Predictor of Thinness and Low Self-rated Health: Gender Differences in a Swedish Cohort

To examine the relationship between leisure time physical activity in 15-year-old students, and weight status and self-rated health 3 years later. Data were used from two follow-up waves, one in 2002 (grade 9, age 15 years) and one in 2005 (grade 12, age 18 years) of a cohort of approximately 2,500 adolescents. Adolescents reported height and weight, health behaviors, and self-rated health by a questionnaire at both occasions. Age and gender-specific body mass index cut-off points for thinness, overweight, and obesity were used to assess weight status. Logistic regression analyses were performed with weight status and self-rated health as the outcomes and level of leisure time physical activity as the independent variable. Adjustments were made for parental years of education, student's current smoking habits, and baseline body mass index. As compared with students who were active for more than 4 hours per week during leisure time, being active 2-4 hours (odds ratio [OR]: 4.15, confidence interval [CI]: 1.62-10.60) and <2 hours (OR: 3.92, CI: 1.30-11.78) predicted thinness in boys. In girls, the risk was smaller and became significant at <2 hours per week (OR: 2.57, CI: 1.38-4.77). Overweight or obesity was not significantly predicted by physical activity. A significant risk of low self-rated health was found at follow-up in boys active for <4 hours per week compared with those active for >4 hours per week. Physical activity is important to maintain a healthy body weight and for future self-rated health in boys.