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1.  Establishing a standard definition for child overweight and obesity worldwide: international survey 
BMJ : British Medical Journal  2000;320(7244):1240.
Objective
To develop an internationally acceptable definition of child overweight and obesity, specifying the measurement, the reference population, and the age and sex specific cut off points.
Design
International survey of six large nationally representative cross sectional growth studies.
Setting
Brazil, Great Britain, Hong Kong, the Netherlands, Singapore, and the United States.
Subjects
97 876 males and 94 851 females from birth to 25 years of age.
Main outcome measure
Body mass index (weight/height2).
Results
For each of the surveys, centile curves were drawn that at age 18 years passed through the widely used cut off points of 25 and 30 kg/m2 for adult overweight and obesity. The resulting curves were averaged to provide age and sex specific cut off points from 2-18 years.
Conclusions
The proposed cut off points, which are less arbitrary and more internationally based than current alternatives, should help to provide internationally comparable prevalence rates of overweight and obesity in children.
PMCID: PMC27365  PMID: 10797032
2.  Prevalence of thinness in children and adolescents in the Seychelles: comparison of two international growth references 
Nutrition Journal  2011;10:65.
Background
Thinness in children and adolescents is largely under studied, a contrast with abundant literature on under-nutrition in infants and on overweight in children and adolescents. The aim of this study is to compare the prevalence of thinness using two recently developed growth references, among children and adolescents living in the Seychelles, an economically rapidly developing country in the African region.
Methods
Weight and height were measured every year in all children of 4 grades (age range: 5 to 16 years) of all schools in the Seychelles as part of a routine school-based surveillance program. In this study we used data collected in 16,672 boys and 16,668 girls examined from 1998 to 2004. Thinness was estimated according to two growth references: i) an international survey (IS), defining three grades of thinness corresponding to a BMI of 18.5, 17.0 and 16.0 kg/m2 at age 18 and ii) the WHO reference, defined here as three categories of thinness (-1, -2 and -3 SD of BMI for age) with the second and third named "thinness" and "severe thinness", respectively.
Results
The prevalence of thinness was 21.4%, 6.4% and 2.0% based on the three IS cut-offs and 27.7%, 6.7% and 1.2% based on the WHO cut-offs. The prevalence of thinness categories tended to decrease according to age for both sexes for the IS reference and among girls for the WHO reference.
Conclusion
The prevalence of the first category of thinness was larger with the WHO cut-offs than with the IS cut-offs while the prevalence of thinness of "grade 2" and thinness of "grade 3" (IS cut-offs) was similar to the prevalence of "thinness" and "severe thinness" (WHO cut-offs), respectively.
doi:10.1186/1475-2891-10-65
PMCID: PMC3121668  PMID: 21658236
3.  First growth curves based on the World Health Organization reference in a Nationally-Representative Sample of Pediatric Population in the Middle East and North Africa (MENA): the CASPIAN-III study 
BMC Pediatrics  2012;12:149.
Background
The World Health Organization (WHO) is in the process of establishing a new global database on the growth of school children and adolescents. Limited national data exist from Asian children, notably those living in the Middle East and North Africa (MENA). This study aimed to generate the growth chart of a nationally representative sample of Iranian children aged 10–19 years, and to explore how well these anthropometric data match with international growth references.
Methods
In this nationwide study, the anthropometric data were recorded from Iranian students, aged 10–19 years, who were selected by multistage random cluster sampling from urban and rural areas. Prior to the analysis, outliers were excluded from the features height-for-age and body mass index (BMI)-for-age using the NCHS/WHO cut-offs. The Box-Cox power exponential (BCPE) method was used to calculate height-for-age and BMI-for-age Z-scores for our study participants. Then, children with overweight, obesity, thinness, and severe thinness were identified using the BMI-for-age z-scores. Moreover, stunted children were detected using the height-for-age z-scores. The growth curve of the Iranian children was then generated from the z-scores, smoothed by cubic S-plines.
Results
The study population comprised 5430 school students consisting of 2312 (44%) participants aged 10–14 years , and 3118 (58%) with 15–19 years of age. Eight percent of the participants had low BMI (thinness: 6% and severe thinness: 2%), 20% had high BMI (overweight: 14% and obesity: 6%), and 7% were stunted. The prevalence rates of low and high BMI were greater in boys than in girls (P < 0.001). The mean BMI-for-age, and the average height-for-age of Iranian children aged 10–19 years were lower than the WHO 2007 and United states Centers for Disease Control and Prevention 2000 (USCDC2000) references.
Conclusions
The current growth curves generated from a national dataset may be included for establishing WHO global database on children’s growth. Similar to most low-and middle income populations, Iranian children aged 10–19 years are facing a double burden of weight disorders, notably under- and over- nutrition, which should be considered in public health policy-making.
doi:10.1186/1471-2431-12-149
PMCID: PMC3471000  PMID: 22985219
Growth; Iran; Reference curve; Weight disorder
4.  Appropriate Body Mass Index Cut-Offs to Determine Thinness, Overweight and Obesity in South Asian Children in The Netherlands 
PLoS ONE  2013;8(12):e82822.
Background
Asian populations have an increased risk of developing cardiometabolic disorders at a lower body mass index (BMI) than other ethnic groups. Therefore, lower adult BMI cut-offs to determine overweight and obesity are recommended to assess the associated health risks for Asian (23 and 27.5 kg/m2 respectively) and Asian Indian (23, 25 kg/m2) populations. The objective of this study was to develop BMI cut-offs for thinness, overweight, and obesity for South Asian children in the Netherlands, and to compare the BMI cut-offs and distribution with an Asian Indian reference, the WHO Child Growth Reference, and universal BMI cut-offs.
Methods
A reference cohort of 546 Surinamese South Asian boys and 521 girls, born between 1974–1976 (during the pre-obesity era) with 3408 and 3267 BMI measurements respectively, was retrospectively analysed. BMI-for-age charts were created with the LMS method. BMI centile curves passing through the cut-off points of 15 (thinness), 23 (overweight), 25 and 27.5 kg/m2 (obesity) at 18y were drawn as cut-off levels.
Results
The BMI of Surinamese South Asian children had a similar distribution to the Asian Indian reference, apart from a lower mean and less variation. The BMI distribution differed considerably from the WHO reference and universal BMI criteria. The calculated BMI cut-offs corresponding to a BMI of 15, 23, 25, and 27.5 kg/m2 at 18y were at the 7.1, 81.1, 89.8, and 95.5 percentile respectively in boys, and at the 2.7, 79.5, 89.2, and 95.2 percentile in girls.
Conclusions
This is the first study proposing BMI cut-offs for South Asian children based on measurements from a prosperous population unaffected by the obesity epidemic. We recommend the use of these cut-offs in South Asian children in the Netherlands as these better reflect the health risks associated with thinness, overweight and obesity, and therefore may prevent the development of cardiometabolic disorders.
doi:10.1371/journal.pone.0082822
PMCID: PMC3868582  PMID: 24367559
5.  Height, weight and BMI percentiles and nutritional status relative to the international growth references among Pakistani school-aged children 
BMC Pediatrics  2012;12:31.
Background
Child growth is internationally recognized as an important indicator of nutritional status and health in populations. This study was aimed to compare age- and gender-specific height, weight and BMI percentiles and nutritional status relative to the international growth references among Pakistani school-aged children.
Methods
A population-based study was conducted with a multistage cluster sample of 1860 children aged five to twelve years in Lahore, Pakistan. Smoothed height, weight and BMI percentile curves were obtained and comparison was made with the World Health Organization 2007 (WHO) and United States' Centers for Disease Control and Prevention 2000 (USCDC) references. Over- and under-nutrition were defined according to the WHO and USCDC references, and the International Obesity Task Force (IOTF) cut-offs. Simple descriptive statistics were used and statistical significance was considered at P < 0.05.
Results
Height, weight and BMI percentiles increased with age among both boys and girls, and both had approximately the same height and a lower weight and BMI as compared to the WHO and USCDC references. Mean differences from zero for height-, weight- and BMI-for-age z score values relative to the WHO and USCDC references were significant (P < 0.001). Means of height-for-age (present study: 0.00, WHO: -0.19, USCDC: -0.24), weight-for-age (present study: 0.00, WHO: -0.22, USCDC: -0.48) and BMI-for-age (present study: 0.00, WHO: -0.32, USCDC: -0.53) z score values relative to the WHO reference were closer to zero and the present study as compared to the USCDC reference. Mean differences between weight-for-age (0.19, 95% CI 0.10-0.30) and BMI-for-age (0.21, 95% CI 0.11-0.30) z scores relative to the WHO and USCDC references were significant. Over-nutrition estimates were higher (P < 0.001) by the WHO reference as compared to the USCDC reference (17% vs. 15% overweight and 7.5% vs. 4% obesity) while underweight and thinness/wasting were lower (P < 0.001) by the WHO reference as compared to the USCDC reference (7% vs. 12% underweight and 10% vs. 13% thinness). Significantly lower overweight (8%) and obesity (5%) prevalence and higher thinness grade one prevalence (19%) was seen with use of the IOTF cut-offs as compared to the WHO and USCDC references. Mean difference between height-for-age z scores and difference in stunting prevalence relative to the WHO and USCDC references was not significant.
Conclusion
Pakistani school-aged children significantly differed from the WHO and USCDC references. However, z score means relative to the WHO reference were closer to zero and the present study as compared to the USCDC reference. Overweight and obesity were significantly higher while underweight and thinness/wasting were significantly lower relative to the WHO reference as compared to the USCDC reference and the IOTF cut-offs. New growth charts for Pakistani children based on a nationally representative sample should be developed. Nevertheless, shifting to use of the 2007 WHO child growth reference might have important implications for child health programs and primary care pediatric clinics.
doi:10.1186/1471-2431-12-31
PMCID: PMC3337223  PMID: 22429910
6.  Glycolipid metabolic status of overweight/obese adolescents aged 9- to 15-year-old and the BMI-SDS/BMI cut-off value of predicting dyslipidemiain boys, Shanghai, China: a cross-sectional study 
Background
The prevalence of adolescents’ obesity and overweight has dramatically elevated in China. Obese children were likely to insulin resistance and dyslipidemia, which are risk factors of cardiovascular diseases. However there was no cut-off point of anthropometric values to predict the risk factors in Chinese adolescents. The present study was to investigate glycolipid metabolism status of adolescents in Shanghai and to explore the correlations between body mass index standard deviation score (BMI-SDS) and metabolic indices, determine the best cut-off value of BMI-SDS to predict dyslipidemia.
Methods
Fifteen schools in Shanghai’s two districts were chosen by cluster sampling and primary screening was done in children aged 9-15 years old. After screening of bodyweight and height, overweight and obese adolescents and age-matched children with normal body weight were randomly recruited in the study. Anthropometric measurements, biochemical measurements of glycolipid profiles were done. SPSS19.0 was used to analyze the data. Receiver operating characteristic (ROC) curves were made and the best cut-off values of BMI-SDS to predict dyslipidemia were determined while the Youden indices were maximum.
Results
Five hundred and thirty-eight adolescents were enrolled in this research, among which 283 have normal bodyweight, 115 were overweight and 140 were obese. No significant differences of the ages among 3 groups were found. There were significant differences of WC-SDS (p<0.001), triacylglycerol (p<0.05), high and low density lipoprotein cholesterol (p<0.01), fasting insulin (p<0.01) and C-peptide (p<0.001) among 3 groups. Significant difference of fasting glucose was only found between normal weight and overweight group. Significant difference of total cholesterol was found between obese and normal weight group. There was no significant difference of glycated hemoglobin among 3 groups. The same tendency was found in boys but not in girls. Only HDL-C reduced and TG increased while BMI elevated in girls. The best cut-off value of BMI-SDS was 1.22 to predict dyslipidemia in boys. The BMI cut-off was 21.67 in boys.
Conclusion
Overweight and obese youths had reduced insulin sensitivity and high prevalence of dyslipidemia.When BMI-SDS elevated up to 1.22 and BMI was higher than 21.67 in boys, dyslipidemia may happen.
doi:10.1186/1476-511X-12-129
PMCID: PMC3766195  PMID: 23984682
Adolescents; Children; Lipid metabolism; Obesity; Overweight; BMI-SDS; China
7.  Assessment of Under Nutrition of Bangladeshi Adults Using Anthropometry: Can Body Mass Index Be Replaced by Mid-Upper-Arm-Circumference? 
PLoS ONE  2015;10(4):e0121456.
Background and Objective
Body-mass-index (BMI) is widely accepted as an indicator of nutritional status in adults. Mid-upper-arm-circumference (MUAC) is another anthropometric-measure used primarily among children. The present study attempted to evaluate the use of MUAC as a simpler alternative to BMI cut-off <18.5 to detect adult undernutrition, and thus to suggest a suitable cut-off value.
Methods
A cross-sectional study in 650 adult attendants of the patients of Dhaka-Hospital, of the International Centre for Diarrheal Disease Research, Bangladesh (icddr,b) was conducted during 2012. Height, weight and MUAC of 260 male and 390 female aged 19–60 years were measured. Curve estimation was done to assess the linearity and correlation of BMI and MUAC. Sensitivity and specificity of MUAC against BMI<18.5 was determined. Separate Receiver-operating-characteristic (ROC) analyses were performed for male and female. Area under ROC curve and Youden's index were generated to aid selection of the most suitable cut-off value of MUAC for undernutrition. A value with highest Youden's index was chosen for cut-off.
Results
Our data shows strong significant positive correlation (linear) between MUAC and BMI, for males r = 0.81, (p<0.001) and for females r = 0.828, (p<0.001). MUAC cut-off <25.1 cm in males (AUC 0.930) and <23.9 cm in females (AUC 0.930) were chosen separately based on highest corresponding Youden's index. These values best correspond with BMI cut-off for under nutrition (BMI <18.5) in either gender.
Conclusion
MUAC correlates closely with BMI. For the simplicity and easy to remember MUAC <25 cm for male and <24 cm for female may be considered as a simpler alternative to BMI cut-off <18.5 to detect adult undernutrition.
doi:10.1371/journal.pone.0121456
PMCID: PMC4397021  PMID: 25875397
8.  Body Mass Index Reference Curves for Children Aged 0-18 Years in Shaanxi, China 
Objectives:
Health care professionals have recommended the use of age-related body mass index (BMI) to evaluate obesity in children. Until now, no age-related reference curves for BMI have been reported in China. Presented here are age-related BMI percentile curves for children aged 0~18 years in Shaanxi, China, 1995.
Methods:
The Third Nationwide Growth Survey was performed in 1995 and from this survey, data of the Shaanxi population were retrieved to construct the age-related BMI percentile curves. A total of 27,200 healthy children aged 0~18 years were examined for height and weight, using the standardized methods. The λ-median-coefficient of variation (LMS) method was used for curve fitting; all analyses were carried out on the basis of different sexes and areas through a special program for LMS method.
Results:
Median BMI increased steeply in early life, with a peak at 8 months, then declined, and then leveled off at about 6 years. The age of adiposity rebound for urban children was about two years earlier than that for rural children and one year earlier for boys than for girls. After adiposity rebound, BMI increased more rapidly in girls than in boys, and the increase in urban children was more rapid than that in rural children. As the onset of puberty, female BMI became higher than that of males, and the difference between boys and girls was larger for rural children than for urban children. The 95th, 50th and 5th percentiles for Shaanxi children were lower than those of comparable American children. Cut-off points for obesity was lower than those of international averages, suggesting the nutrition status of Shaanxi children is lower than that of children in developed countries, and has not reached the international average level.
Conclusions:
Using the LMS method, we constructed age-related BMI percentile curves for Shaanxi children aged 0~18 years, the first for Chinese children. Percentile curves and cut-off points for obesity can be used as a reference for assessing the nutrition status of Shaanxi children aged 0~18 years. The identified gender and residency differences may serve as guides to an understanding of the cause and prevention of obesity.
PMCID: PMC3614580  PMID: 23674955
body mass index; growth reference; obesity; Chinese children
9.  How Has the Age-Related Process of Overweight or Obesity Development Changed over Time? Co-ordinated Analyses of Individual Participant Data from Five United Kingdom Birth Cohorts 
PLoS Medicine  2015;12(5):e1001828.
Background
There is a paucity of information on secular trends in the age-related process by which people develop overweight or obesity. Utilizing longitudinal data in the United Kingdom birth cohort studies, we investigated shifts over the past nearly 70 years in the distribution of body mass index (BMI) and development of overweight or obesity across childhood and adulthood.
Methods and Findings
The sample comprised 56,632 participants with 273,843 BMI observations in the 1946 Medical Research Council National Survey of Health and Development (NSHD; ages 2–64 years), 1958 National Child Development Study (NCDS; 7–50), 1970 British Cohort Study (BCS; 10–42), 1991 Avon Longitudinal Study of Parents and Children (ALSPAC; 7–18), or 2001 Millennium Cohort Study (MCS; 3–11). Growth references showed a secular trend toward positive skewing of the BMI distribution at younger ages. During childhood, the 50th centiles for all studies lay in the middle of the International Obesity Task Force normal weight range, but during adulthood, the age when a 50th centile first entered the overweight range (i.e., 25–29.9 kg/m2) decreased across NSHD, NCDS, and BCS from 41 to 33 to 30 years in males and 48 to 44 to 41 years in females. Trajectories of overweight or obesity showed that more recently born cohorts developed greater probabilities of overweight or obesity at younger ages. Overweight or obesity became more probable in NCDS than NSHD in early adulthood, but more probable in BCS than NCDS and NSHD in adolescence, for example. By age 10 years, the estimated probabilities of overweight or obesity in cohorts born after the 1980s were 2–3 times greater than those born before the 1980s (e.g., 0.229 [95% CI 0.219–0.240] in MCS males; 0.071 [0.065–0.078] in NSHD males). It was not possible to (1) model separate trajectories for overweight and obesity, because there were few obesity cases at young ages in the earliest-born cohorts, or (2) consider ethnic minority groups. The end date for analyses was August 2014.
Conclusions
Our results demonstrate how younger generations are likely to accumulate greater exposure to overweight or obesity throughout their lives and, thus, increased risk for chronic health conditions such as coronary heart disease and type 2 diabetes mellitus. In the absence of effective intervention, overweight and obesity will have severe public health consequences in decades to come.
In a longitudinal analysis, William Johnson and colleagues examine how individual lifetime BMI trajectories among white citizens of the UK have changed from 1946 to 2014.
Editors' Summary
Background
Overweight and obesity are major threats to global health. The global prevalence of obesity (the proportion of the world's population that is obese) has more than doubled since 1980; 13% of the adult population, or 0.6 billion people, are now classified as obese, while an additional 1.3 billion adults are overweight. Both classifications are determined by body mass index (BMI), which is calculated by dividing a person's weight in kilograms by the square of their height in meters. Obese individuals have a BMI of 30 kg/m2 or more, while overweight individuals have a BMI of 25–30 kg/m2. BMI values above 25 kg/m2 increase the risk of developing non-communicable diseases (NCDs), including cardiovascular diseases, cancers and diabetes. Each year, NCDs kill 38 million people (including 28 million people in low- and middle-income countries and 9 million people under 60 years of age), thereby accounting for more than 75% of the world's annual deaths.
In the United Kingdom, studies report that roughly one quarter of adults are obese, and a further third or more are overweight. This “obesity epidemic” extends to children; according to the National Child Measurement Programme for England (NCMP), about 9% of 4–5-year-olds and 19% of 10–11-year-olds were obese in 2013. In parallel, the UK has not seen the improvements in child and young adult mortality seen in comparable European states.
Why Was This Study Done?
Cross-sectional surveys in the UK, United States, and elsewhere have documented the obesity epidemic, but longitudinal data—drawn from periodic BMI measurements from individuals over their lifetimes—are needed to clarify the time course, or trajectory, of overweight and obesity. Longitudinal data can answer practical questions important for designing health policy interventions. Is the age at which individuals develop overweight or obesity changing over time? In which individuals are the greatest increases in BMI occurring? The authors leveraged longitudinal data from five birth cohort studies (studies that follow a selected group of individuals born during a short window of time), incepted in 1946, 1958, 1970, 1991, and 2001. These large cohort projects were funded by the UK government for the purpose of providing data for long-term health analyses such as this one; in total, the current study’s included sample comprised 56,632 participants with 273,843 BMI observations from participants aged 2 through 64.
What Did the Researchers Do and Find?
The present study aimed to investigate (1) shifts from the 1940s to the 2000s in the distribution of BMI across age and (2) shifts over the same period in the probability of developing overweight or obesity across age. For each of the five cohorts, subdivided by sex and childhood versus adulthood (thus, a total of 20 datasets), the authors applied statistical models to produce trajectories for each BMI centile (subset that results from dividing the distribution of BMI measurements into 100 groups with equal frequency; here, the 90th centile is the group for which 90% of the relevant population has lower BMI). They then investigated secular trends (long-term, non-periodic variations) at different centiles of the BMI distribution. For example, by comparing the trajectories of the 50th centile for adult males across the five cohorts, the researchers could see how the age at which BMI values reached the obese range varied between eras among this group.
The data revealed that most of the between-cohort, and thus between-era, increases in BMI took place in the highest centiles, indicating that overall gains in BMI mainly comprised very high BMI individuals carrying even more weight. Across the 1946, 1958, and 1970 cohorts, the age at which the 50th centile of adults entered the overweight range decreased from 41 to 33 to 30 years in males and 48 to 44 to 41 years in females. The probabilities of overweight and obesity across adulthood also increased. While children in the 50th BMI centile have remained at normal weight through the decades, the overall childhood probability of developing overweight or obesity has increased 2–3-fold from before to after the 1980s.
What Do These Findings Mean?
These findings describe the changing pattern of age-related progression of overweight and obesity from early childhood in white citizens of the UK. The findings may not be generalizable because other populations have distinct genetic predispositions, environmental exposures, and access to health care. In addition, the accuracy of the findings may be affected by differences between cohorts in how weight and height (and thus BMI) were measured. Nevertheless, these findings—in particular, the increased risk of overweight and obesity at younger ages—suggest that compared to previous generations, current and future generations will accumulate greater overweight or obesity exposure across their lives, likely resulting in increased risk for NCDs. Further research is now needed to determine whether lifestyle factors in the UK have affected the trajectory of BMI and to discover the extent to which these shifting weight trajectories have contributed to morbidity and mortality.
Additional Information
This list of resources contains links that can be accessed when viewing the PDF on a device or via the online version of the article at http://dx.doi.org/10.1371/journal.pmed.1001828. The World Health Organization provides information on obesity and non-communicable diseases around the world (in several languages)The UK National Health Service Choices website also provides detailed information about obesity and a link to a personal story about losing weightThe International Obesity Taskforce provides information about the global obesity epidemicThe US Centers for Disease Control and Prevention provides information on non-communicable diseases around the world and on overweight and obesity and diabetes (including some information in Spanish)The US Department of Agriculture's ChooseMyPlate.gov website provides a personal healthy eating planThe Weight-control Information Network is an information service provided for the general public and health professionals by the US National Institute of Diabetes and Digestive and Kidney Diseases (in English and Spanish)MedlinePlus has links to further information about obesity (in English and Spanish)
doi:10.1371/journal.pmed.1001828
PMCID: PMC4437909  PMID: 25993005
10.  Weight status among Iranian adolescents: Comparison of four different criteria 
Background:
Obesity or being overweight is a major health problem in Iran. Only few studies are available that compare the obesity prevalence by four different available criteria. The aim of this study was to determine the prevalence of overweight and obesity among Isfahani adolescents based on four different definitions.
Materials and Methods:
This cross-sectional study was conducted on 3002 Isfahani students (1377 males; 1625 females) aged 11-18 years. Anthropometric measurements including weight and height were measured and body mass index (BMI) was calculated. Sex-specific BMI-for-age reference data of the Iranian national data, Center for Disease Control data (CDC2000), International Obesity taskforce data (IOTF), and recent World Health Organization (WHO) data was used to define overweight and obesity.
Results:
The mean age of the studied population was 14.8 years and the mean BMI was 20.3 kg/m2. Girls were on an average 1.4 years older and had almost one unit higher BMI than boys. Underweight was prevalent among almost 38.5% and 25.5% of adolescents as per WHO2007 and national Iranian cut-off points, respectively. The prevalence rates reached 39.5% and 45.8% by IOTF and CDC2000 criteria, respectively. The highest prevalence of overweight was obtained by IOTF cut-points (30.5%), while CDC2000 criteria, WHO2007, and national Iranian cut-points gave similar prevalence results (4.7%, 4.0%, and 4.4%); 2.4% of the studied population were found to be obese by WHO2007 definition, while this rate was 0.8%, 0.5%, and 0.8% by IOTF, CDC2000, and national Iranian cut-points.
Conclusion:
Almost all definitions revealed coexistence of underweight, overweight, and obesity among Isfahani adolescents. Huge differences exist between different criteria for assessing weight status among children. To understand the best appropriate criteria for Iranian adolescents, future studies should focus on the predictability of obesity related co-morbidities by these criteria.
PMCID: PMC3872601  PMID: 24379838
Adolescents; body mass index; obesity; overweight; prevalence; weight
11.  Defining Body Fatness in Adolescents: A Proposal of the Afad-A Classification 
PLoS ONE  2013;8(2):e55849.
Aims
Body mass index (BMI) shows several limitations as indicator of fatness. Using the International Obesity Task Force (IOTF) reference and the World Health Organization (WHO) standard 2007 on the same dataset yielded widely different rates. At higher levels, BMI and the BMI cut-offs may be help in informing a clinical judgement, but at levels near the norm additional criteria may be needed. This study compares the prevalence of overweight and obesity using IOTF and WHO-2007 references and interprets body composition by comparing measures of BMI and body fatness (fat mass index, FMI; and waist-to-height ratio, WHtR) among an adolescent population.
Methods and Results
A random sample (n = 1231) of adolescent population (12–17 years old) was interviewed. Weight, height, waist circumference, triceps and subscapular skinfolds were used to calculate BMI, FMI, and WHtR. The prevalence of overweight and obesity were 12.3% and 15.4% (WHO standards) and 18.6% and 6.1% (IOTF definition). Despite that IOTF cut-offs misclassified less often than WHO standards, BMI categories were combined with FMI and WHtR resulting in the Adiposity & Fat Distribution for adolescents (AFAD-A) classification, which identified the following groups normal-weight normal-fat (73.2%), normal-weight overfat (2.1%), overweight normal-fat (6.7%), overweight overfat (11.9%) and obesity (6.1%), and also classified overweight at risk and obese adolescents into type-I (9.5% and 1.3%, respectively) and type-II (2.3% and 4.9%, respectively) depending if they had or not abdominal fatness.
Conclusions
There are differences between IOTF and WHO-2007 international references and there is a misclassification when adiposity is considered. The BMI limitations, especially for overweight identification, could be reduced by adding an estimate of both adiposity (FMI) and fat distribution (WHtR). The AFAD-A classification could be useful in clinical and population health to identify overfat adolescent and those who have greater risk of developing weight-related cardiovascular diseases according to the BMI category.
doi:10.1371/journal.pone.0055849
PMCID: PMC3566104  PMID: 23405220
12.  Cut-off Values of Body Mass Index, Waist Circumference, and Waist-to-Height Ratio to Identify Excess Abdominal Fat: Population-Based Screening of Japanese Schoolchildren 
Journal of Epidemiology  2011;21(3):191-196.
Background
School-based screening and prevention programs for adiposity generally target school children in grades 4 and 6 (age 9–11 years). The aims of this study were to evaluate the validity of body mass index (BMI), waist circumference (WC), and waist-to-height ratio (WHtR) in identifying abdominal adiposity in fifth-grade Japanese school children and to determine optimal cut-off values for anthropometric measures.
Methods
The target population was fifth-grade school children enrolled in 2 schools in Shizuoka, Japan between 2008 and 2010; 422 of the 466 children participated in the present study. Abdominal adiposity was defined as percent trunk fat in the 95th percentile or higher, as determined by dual-energy x-ray absorptiometry (DXA). We analyzed the validity of BMI, WC, and WHtR using receiver operating characteristic (ROC) curve analysis. The Youden index was used to determine cut-off values of BMI, WC, and WHtR that identify excess abdominal fat.
Results
Optimal cut-off values to identify abdominal adiposity were 20.8 kg/m2 (BMI), 76.5 cm (WC), and 0.519 (WHtR) for boys, and 19.6 kg/m2 (BMI), 73.0 cm (WC), and 0.499 (WHtR) for girls. Areas under the ROC curve were 0.983 (BMI), 0.987 (WC), and 0.981 (WHtR) for boys, and 0.981 (BMI), 0986 (WC), and 0.992 (WHtR) for girls.
Conclusions
BMI, WC, and WHtR successfully identified a high proportion of children with excess abdominal fat as measured by DXA, demonstrating that these measures are useful indices for school screening.
doi:10.2188/jea.JE20100116
PMCID: PMC3899408  PMID: 21467729
child; screening; obesity; statistics as topic; reference values
13.  Waist circumference, waist-to-hip ratio and waist-to-height ratio reference percentiles for abdominal obesity among Greek adolescents 
BMC Pediatrics  2015;15:50.
Background
Indices predictive of adolescent central obesity include waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR). Such reference data are lacking for Greek adolescents. The aim of this study was to develop age- and gender-specific WC, WHR and WHtR smoothed reference percentiles for abdominal obesity among Greek adolescents aged 12–17 years, to investigate possible obesity cut-offs of WHR and WHtR and to compare WC percentiles to other adolescent populations.
Methods
A representative sample of 1610 high school adolescents (42.2% boys, 57.8% girls; mean age ± sd 14.4 ± 1.72 years) participated in this cross-sectional study in Attica, Greece, in 2013. Weight, height, body mass index (BMI), WC, hip circumference (HC), WHR and WHtR were measured and percentiles were calculated using the LMS method. The relation between WHR, WHtR and general obesity, as defined by the International Obesity Task Force, was investigated with receiver operating characteristic (ROC) analysis. The discriminating power of WHR and WHtR was expressed as area under the curve (AUC). Greek adolescents’ WC measurements at the 50th and 90th percentile were compared with their counterparts’ smoothed percentiles from Norway, Turkey, Poland, South India, Germany and Kuwait.
Results
Boys had significantly higher mean in all measures than girls, except for BMI where there was no statistical difference in terms of gender. BMI, WC and HC showed an increasing trend with age. WC leveled off in both genders at the age of 17 years. WHR and WHtR showed a continuous decrease with advancing age. WHtR was a better predictor for general obesity in both boys and girls (AUC 95% CI 0.945-0.992) than the WHR (AUC 95% CI 0.758-0.870); the WHtR cut-off of 0.5 had sensitivity 91% and specificity 95% for both genders and all age groups combined. International comparisons showed that Greek adolescents had relatively high levels of abdominal obesity in early-middle adolescence but this did not persist at the age of 17 years.
Conclusions
These reference percentile curves could be used provisionally for early detection of abdominal obesity in Greek adolescents aged 12–17 years; WHtR of 0.5 could also be used as a threshold for obesity in this age group.
doi:10.1186/s12887-015-0366-z
PMCID: PMC4446827  PMID: 25935716
Percentiles; Waist circumference; Waist-hip ratio; Waist-height ratio; Abdominal obesity; Greece; Adolescents
14.  Defining overweight and obesity among Greek children living in Thessaloniki: International versus local reference standards 
Hippokratia  2011;15(2):141-146.
Background: Body Mass Index (BMI) offers a simple and reasonable measure of obesity that, with the use of the appropriate reference, can help in the early detection of children with weight problems. Our aim was to compare the two most commonly used international BMI references and the national Greek BMI reference in identifying Greek children being overweight and obese.
Methods: A group of 1557 children (820 girls and 737 boys, mean age: 11.42 ± 3.51 years) were studied. Weight and height was measured using standard methods, and BMI was calculated. Overweight and obesity were determined using the International Obesity Task Force (IOTF) standards, the Centers for Disease Control and Prevention (CDC) BMI-forage curves and the most recent Greek BMI-for-age curves.
Results: Results showed that the IOTF's cut-off limits identifies a significantly higher prevalence of overweight (22.4%) compared with both the CDC's (11.8%, p=0.03) and the Greek's (7.4%, p=0.002) cut-off limits. However, the prevalence of obesity was generally increased when it was determined using the CDC's cut-off limits (13.9%) compared to the prevalence calculated with both the IOTF's (6.5%, p=0.05) and the Greek's (6.9%, n.s.) cut off limits.
Conclusions: The use of the national Greek reference standards for BMI underestimates the true prevalence of overweight and obesity. On the contrary, both the IOTF and the CDC standards, although independently, detect an increased number of overweight and obese children and thus they should be adopted in the clinical practice for an earlier identification and a timelier intervention.
PMCID: PMC3209677  PMID: 22110296
children; obesity; overweight; BMI; Greek
15.  The association of self-esteem, depression and body satisfaction with obesity among Turkish adolescents 
BMC Public Health  2007;7:80.
Background
The purpose of this study was to determine the prevalence of overweight and obesity and to examine the effects of actual weight status, perceived weight status and body satisfaction on self-esteem and depression in a high school population in Turkey.
Methods
A cross-sectional survey of 2101 tenth-grade Turkish adolescents aged 15–18 was conducted. Body mass index (BMI) was calculated using weight and height measures. The overweight and obesity were based on the age- and gender-spesific BMI cut-off points of the International Obesity Task Force values. Self-esteem was measured using the Rosenberg Self-Esteem Scale, and depression was measured using Children's Depression Inventory. Logistic regression analysis was used to examine relationships among the variables.
Results
Based on BMI cut-off points, 9.0% of the students were overweight and 1.1% were obese. Logistic regression analysis indicated that (1) being male and being from a higher socio-economical level were important in the prediction of overweight based on BMI; (2) being female and being from a higher socio-economical level were important in the prediction of perceived overweight; (3) being female was important in the prediction of body dissatisfaction; (4) body dissatisfaction was related to low self-esteem and depression, perceived overweight was related only to low self-esteem but actual overweight was not related to low self-esteem and depression in adolescents.
Conclusion
The results of this study suggest that school-based adolescents in urban Turkey have a lower risk of overweight and obesity than adolescents in developed countries. The findings of this study suggest that psychological well-being of adolescents is more related to body satisfaction than actual and perceived weight status is.
doi:10.1186/1471-2458-7-80
PMCID: PMC1888702  PMID: 17506879
16.  Secular changes in height, weight and body mass index in Hong Kong Children 
BMC Public Health  2008;8:320.
Background
Large population growth surveys of children and adolescents aged 6 to 18 y were undertaken in Hong Kong in 1963 and 1993. The global epidemic of obesity is a major public health concern. To monitor the impact of this epidemic in Hong Kong children and to identify secular changes in growth, a further growth survey was undertaken in 2005/6.
Methods
Cross-sectional height and weight measurements of 14,842 children and adolescents aged 6 to 18 y from Hong Kong's 18 districts were obtained during the 2005/6 school year. Percentile curves were constructed using LMS method and sex-specific percentile values of weight-for-age, height-for-age, and BMI-for-age were compared with those data from 1963 and 1993.
Results
Secular changes in height, weight and BMI were noted between 1963 and 1993 and between 1993 and 2005/6. In the latter period, greater changes were observed at younger ages, and particularly in boys. On an annual basis, the 1993–2005/6 changes were less than those during 1963–1993. Using the International Obesity Task Force cut-offs, 16.7% of children were overweight or obese in 2005/6, which was a 5.1% increase since 1993.
Conclusion
These data provide policy-makers with further evidence of the secular changes in child growth and the increasing obesity epidemic among Hong Kong children.
doi:10.1186/1471-2458-8-320
PMCID: PMC2572616  PMID: 18803873
17.  Change in the Body Mass Index Distribution for Women: Analysis of Surveys from 37 Low- and Middle-Income Countries 
PLoS Medicine  2013;10(1):e1001367.
Using cross-sectional surveys, Fahad Razak and colleagues investigate how the BMI (body mass index) distribution is changing for women in low- and middle-income countries.
Background
There are well-documented global increases in mean body mass index (BMI) and prevalence of overweight (BMI≥25.0 kg/m2) and obese (BMI≥30.0 kg/m2). Previous analyses, however, have failed to report whether this weight gain is shared equally across the population. We examined the change in BMI across all segments of the BMI distribution in a wide range of countries, and assessed whether the BMI distribution is changing between cross-sectional surveys conducted at different time points.
Methods and Findings
We used nationally representative surveys of women between 1991–2008, in 37 low- and middle-income countries from the Demographic Health Surveys ([DHS] n = 732,784). There were a total of 96 country-survey cycles, and the number of survey cycles per country varied between two (21/37) and five (1/37). Using multilevel regression models, between countries and within countries over survey cycles, the change in mean BMI was used to predict the standard deviation of BMI, the prevalence of underweight, overweight, and obese. Changes in median BMI were used to predict the 5th and 95th percentile of the BMI distribution. Quantile-quantile plots were used to examine the change in the BMI distribution between surveys conducted at different times within countries. At the population level, increasing mean BMI is related to increasing standard deviation of BMI, with the BMI at the 95th percentile rising at approximately 2.5 times the rate of the 5th percentile. Similarly, there is an approximately 60% excess increase in prevalence of overweight and 40% excess in obese, relative to the decline in prevalence of underweight. Quantile-quantile plots demonstrate a consistent pattern of unequal weight gain across percentiles of the BMI distribution as mean BMI increases, with increased weight gain at high percentiles of the BMI distribution and little change at low percentiles. Major limitations of these results are that repeated population surveys cannot examine weight gain within an individual over time, most of the countries only had data from two surveys and the study sample only contains women in low- and middle-income countries, potentially limiting generalizability of findings.
Conclusions
Mean changes in BMI, or in single parameters such as percent overweight, do not capture the divergence in the degree of weight gain occurring between BMI at low and high percentiles. Population weight gain is occurring disproportionately among groups with already high baseline BMI levels. Studies that characterize population change should examine patterns of change across the entire distribution and not just average trends or single parameters.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
The number of obese people (individuals who have an excessive amount of body fat) is rapidly increasing in many countries. Globally, there were about 200 million obese adults in 1995; by 2010, 475 million adults were obese and another billion were classified as overweight. Obesity is defined as having a body mass index (BMI, an indicator of body fat calculated by dividing a person's weight in kilograms by their height in meters squared) of more than 30.0 kg/m2. Compared to people with a healthy weight (a BMI between 18.5 and 24.9 kg/m2), obese individuals and overweight individuals (who have a BMI between 25.0 and 29.9 kg/m2) have an increased risk of developing diabetes, heart disease and stroke, and tend to die younger. At the same time in many developing countries substantial numbers of people are underweight (BMI <18.5 kg/m2) or have chronic energy deficiency (BMI <16.0 kg/m2) and are at risk of increased risk of dying due to infectious disease or respiratory problems.
Why Was This Study Done?
The global obesity epidemic is usually described in terms of increases in the average BMI or in the prevalence of obesity (the proportion of the population whose BMI is above 30.0 kg/m2). Such descriptions assume that the BMIs of fat and thin people are increasing at the same rate and that the shape of the population's BMI distribution curve remains constant. However, as average BMI and the prevalence of obesity can increase it is unclear how the prevalence of underweight changes. This is potentially important for the health of the population because underweight individuals, like obese individuals, tend to die younger than healthy weight individuals, particularly in low-income countries. In this study, the researchers use repeated cross-sectional survey data collected from low- and middle-income countries in the Demographic and Health Surveys (DHS) to examine changes in BMI in women across the BMI distribution between 1991 and 2008. Repeated cross-sectional surveys collect data from a population at multiple time points from different individuals drawn from the same population, DHS are a data collection and surveillance project that help developing countries track health and population trends.
What Did the Researchers Do and Find?
The researchers used statistical models to analyze data from DHS surveys of more than 730,000 women living in 37 low- and middle-income countries (two to five surveys per country). Increasing average BMI was associated with an increase in the standard deviation of BMI (a measure of the dispersion of BMI in the population) both across and within countries over time. With increasing average BMI, the BMI at both the 5th and 95th percentile increased; 90% of the BMIs in a population lie between these percentiles so these BMI values indicate the spread of the BMI distribution. However, the BMI at the 95th percentile increased about 2.5 times faster than the BMI at the 5th percentile. Moreover, with increasing average BMI, the prevalence of overweight and obesity increased faster than the decline in the prevalence of underweight. Finally, quantile-quantile plots for each country (a graphical method that compares two distributions) revealed a consistent pattern of unequal weight gain across the BMI distribution as average BMI increased, with pronounced weight gains at the obese end of the distribution and little change at the underweight end.
What Do These Findings Mean?
These findings show that increases in average BMI are associated with an increased spread of BMI across and within populations. Consequently, changes in average BMI or single measurements such as the prevalence of overweight do not capture the divergence in the degree of weight gain occurring between that part of the population that has a low BMI and that part that has a high BMI. In other words, at least for the low- and middle-income countries included in this study, population weight gain is occurring disproportionately among groups with high baseline BMI levels. The researchers suggest, therefore, that the characterization of the BMI of populations over time should examine the patterns of change across the whole BMI distribution. Moreover, rather than a single broad population strategy for weight control, optimum health outcomes, they suggest, might be achieved by a strategy that includes targeted interventions to reduce weight in high BMI segments of the population and to increase weight in low BMI segments.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001367.
The US Centers for Disease Control and Prevention provides information on all aspects of overweight and obesity (in English and Spanish)
The World Health Organization provides information on obesity (in several languages); Malri's story describes the health risks faced by an obese child
The UK National Health Service Choices website also provides detailed information about obesity and a link to a personal story about losing weight
The International Obesity Taskforce provides information about the global obesity epidemic
The US Department of Agriculture's ChooseMyPlate.gov website provides a personal healthy eating plan; the Weight-control Information Network is an information service provided for the general public and health professionals by the US National Institute of Diabetes and Digestive and Kidney Diseases (in English and Spanish)
MedlinePlus has links to further information about obesity (in English and Spanish)
doi:10.1371/journal.pmed.1001367
PMCID: PMC3545870  PMID: 23335861
18.  Genetic Markers of Adult Obesity Risk Are Associated with Greater Early Infancy Weight Gain and Growth 
PLoS Medicine  2010;7(5):e1000284.
Ken Ong and colleagues genotyped children from the ALSPAC birth cohort and showed an association between greater early infancy gains in weight and length and genetic markers for adult obesity risk.
Background
Genome-wide studies have identified several common genetic variants that are robustly associated with adult obesity risk. Exploration of these genotype associations in children may provide insights into the timing of weight changes leading to adult obesity.
Methods and Findings
Children from the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort were genotyped for ten genetic variants previously associated with adult BMI. Eight variants that showed individual associations with childhood BMI (in/near: FTO, MC4R, TMEM18, GNPDA2, KCTD15, NEGR1, BDNF, and ETV5) were used to derive an “obesity-risk-allele score” comprising the total number of risk alleles (range: 2–15 alleles) in each child with complete genotype data (n = 7,146). Repeated measurements of weight, length/height, and body mass index from birth to age 11 years were expressed as standard deviation scores (SDS). Early infancy was defined as birth to age 6 weeks, and early infancy failure to thrive was defined as weight gain between below the 5th centile, adjusted for birth weight. The obesity-risk-allele score showed little association with birth weight (regression coefficient: 0.01 SDS per allele; 95% CI 0.00–0.02), but had an apparently much larger positive effect on early infancy weight gain (0.119 SDS/allele/year; 0.023–0.216) than on subsequent childhood weight gain (0.004 SDS/allele/year; 0.004–0.005). The obesity-risk-allele score was also positively associated with early infancy length gain (0.158 SDS/allele/year; 0.032–0.284) and with reduced risk of early infancy failure to thrive (odds ratio  = 0.92 per allele; 0.86–0.98; p = 0.009).
Conclusions
The use of robust genetic markers identified greater early infancy gains in weight and length as being on the pathway to adult obesity risk in a contemporary birth cohort.
Please see later in the article for the Editors' Summary
Editors' Summary
Background
The proportion of overweight and obese children is increasing across the globe. In the US, the Surgeon General estimates that, compared with 1980, twice as many children and three times the number of adolescents are now overweight. Worldwide, 22 million children under five years old are considered by the World Health Organization to be overweight.
Being overweight or obese in childhood is associated with poor physical and mental health. In addition, childhood obesity is considered a major risk factor for adult obesity, which is itself a major risk factor for cancer, heart disease, diabetes, osteoarthritis, and other chronic conditions.
The most commonly used measure of whether an adult is a healthy weight is body mass index (BMI), defined as weight in kilograms/(height in metres)2. However, adult categories of obese (>30) and overweight (>25) BMI are not directly applicable to children, whose BMI naturally varies as they grow. BMI can be used to screen children for being overweight and or obese but a diagnosis requires further information.
Why Was This Study Done?
As the numbers of obese and overweight children increase, a corresponding rise in future numbers of overweight and obese adults is also expected. This in turn is expected to lead to an increasing incidence of poor health. As a result, there is great interest among health professionals in possible pathways between childhood and adult obesity. It has been proposed that certain periods in childhood may be critical for the development of obesity.
In the last few years, ten genetic variants have been found to be more common in overweight or obese adults. Eight of these have also been linked to childhood BMI and/or obesity. The authors wanted to identify the timing of childhood weight changes that may be associated with adult obesity. Knowledge of obesity risk genetic variants gave them an opportunity to do so now, without following a set of children to adulthood.
What Did the Researchers Do and Find?
The authors analysed data gathered from a subset of 7,146 singleton white European children enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC) study, which is investigating associations between genetics, lifestyle, and health outcomes for a group of children in Bristol whose due date of birth fell between April 1991 and December 1992. They used knowledge of the children's genetic makeup to find associations between an obesity risk allele score—a measure of how many of the obesity risk genetic variants a child possessed—and the children's weight, height, BMI, levels of body fat (at nine years old), and rate of weight gain, up to age 11 years.
They found that, at birth, children with a higher obesity risk allele score were not any heavier, but in the immediate postnatal period they were less likely to be in the bottom 5% of the population for weight gain (adjusted for birthweight), often termed “failure to thrive.” At six weeks of age, children with a higher obesity risk allele score tended to be longer and heavier, even allowing for weight at birth.
After six weeks of age, the obesity risk allele score was not associated with any further increase in length/height, but it was associated with a more rapid weight gain between birth and age 11 years. BMI is derived from height and weight measurements, and the association between the obesity risk allele score and BMI was weak between birth and age three-and-a-half years, but after that age the association with BMI increased rapidly. By age nine, children with a higher obesity risk allele score tended to be heavier and taller, with more fat on their bodies.
What Do These Findings Mean?
The combined obesity allele risk score is associated with higher rates of weight gain and adult obesity, and so the authors conclude that weight gain and growth even in the first few weeks after birth may be the beginning of a pathway of greater adult obesity risk.
A study that tracks a population over time can find associations but it cannot show cause and effect. In addition, only a relatively small proportion (1.7%) of the variation in BMI at nine years of age is explained by the obesity risk allele score.
The authors' method of finding associations between childhood events and adult outcomes via genetic markers of risk of disease as an adult has a significant advantage: the authors did not have to follow the children themselves to adulthood, so their findings are more likely to be relevant to current populations. Despite this, this research does not yield advice for parents how to reduce their children's obesity risk. It does suggest that “failure to thrive” in the first six weeks of life is not simply due to a lack of provision of food by the baby's caregiver but that genetic factors also contribute to early weight gain and growth.
The study looked at the combined obesity risk allele score and the authors did not attempt to identify which individual alleles have greater or weaker associations with weight gain and overweight or obesity. This would require further research based on far larger numbers of babies and children. The findings may also not be relevant to children in other types of setting because of the effects of different nutrition and lifestyles.
Additional Information
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000284.
Further information is available on the ALSPAC study
The UK National Health Service and other partners provide guidance on establishing a healthy lifestyle for children and families in their Change4Life programme
The International Obesity Taskforce is a global network of expertise and the advocacy arm of the International Association for the Study of Obesity. It works with the World Health Organization, other NGOs, and stakeholders and provides information on overweight and obesity
The Centers for Disease Control and Prevention (CDC) in the US provide guidance and tips on maintaining a healthy weight, including BMI calculators in both metric and Imperial measurements for both adults and children. They also provide BMI growth charts for boys and girls showing how healthy ranges vary for each sex at with age
The Royal College of Paediatrics and Child Health provides growth charts for weight and length/height from birth to age 4 years that are based on WHO 2006 growth standards and have been adapted for use in the UK
The CDC Web site provides information on overweight and obesity in adults and children, including definitions, causes, and data
The CDC also provide information on the role of genes in causing obesity.
The World Health Organization publishes a fact sheet on obesity, overweight and weight management, including links to childhood overweight and obesity
Wikipedia includes an article on childhood obesity (note that Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)
doi:10.1371/journal.pmed.1000284
PMCID: PMC2876048  PMID: 20520848
19.  Underweight, Overweight and Obesity Among Zaboli Adolescents: A Comparison Between International and Iranians’ National Criteria 
Background:
Obesity and overweight are the major health problems in Iran. The aim of this study was to determine the prevalence of overweight and obesity among adolescents living in Zabol settled in Sistan va Baluchistan, one of economically underprivileged provinces in South Eastern of Iran, based on four different definitions.
Methods:
This cross-sectional study was accomplished among a sample of 837 Zaboli adolescents (483 males; 354 females) aged 11-15 years. Anthropometric measurements including weight and height were measured and body mass index (BMI) was calculated. Sex-specific BMI-for-age reference data of the Iranian national data, Centers for Disease Control data (CDC 2000), International Obesity Task Force data (IOTF) and recent World Health Organization (WHO) data was used to define overweight and obesity.
Results:
Mean age of the studied population was 13.14 year. Underweight was prevalent among almost 18.7% and 18.4% of adolescents by the use of WHO 2007 and CDC 2000 cut-off points. The prevalence rates reached 25.8% and 27.2% by IOTF and Iranian national criteria, respectively. The highest prevalence of overweight was obtained by IOTF cut-points (10.8%) followed by CDC 2000 criteria (9.4%), WHO 2007 (8.8%) while national Iranian cut-points resulted in the lowest prevalence (2.4%). 7.5% of the studied population were found to be obese by WHO 2007 definition, while this rate was 2.2%, 3.4% and 1.5% by IOTF, CDC 2000 and national Iranian cut-points.
Conclusions:
Almost all definitions revealed coexistence of underweight, overweight, and obesity among Zaboli adolescents. Huge differences exist between different criteria. To understand the best appropriate criteria for Iranian adolescents, future studies should focus on the predictability of obesity-related co-morbidities by these criteria.
PMCID: PMC3733182  PMID: 23930162
Adolescents; body mass index; Iran; obesity; overweight; prevalence; Zabol
20.  Correction of Body-Mass Index Using Body-Shape Perception and Socioeconomic Status in Adolescent Self-Report Surveys 
PLoS ONE  2014;9(5):e96768.
Objectives
To propose a simple correction of body-mass index (BMI) based on self-reported weight and height (reported BMI) using gender, body shape perception and socioeconomic status in an adolescent population.
Methods
341 boys and girls aged 17–18 years were randomly selected from a representative sample of 2165 French adolescents living in Paris surveyed in 2010. After an anonymous self-administered pen-and-paper questionnaire asking for height, weight, body shape perception (feeling too thin, about the right weight or too fat) and socioeconomic status, subjects were measured and weighed. BMI categories were computed according to Cole’s cut-offs. Reported BMIs were corrected using linear regressions and ROC analyses and checked with cross-validation and multiple imputations to handle missing values. Agreement between actual and corrected BMI values was estimated with Kappa indexes and Intraclass correlation coefficients (ICC).
Results
On average, BMIs were underreported, especially among girls. Kappa indexes between actual and reported BMI were low, especially for girls: 0.56 95%CI = [0.42–0.70] for boys and 0.45 95%CI = [0.30–0.60] for girls. The regression of reported BMI by gender and body shape perception gave the most balanced results for both genders: the Kappa and ICC obtained were 0.63 95%CI = [0.50–0.76] and 0.67, 95%CI = [0.58–0.74] for boys; 0.65 95%CI = [0.52–0.78] and 0.74, 95%CI = [0.66–0.81] for girls. The regression of reported BMI by gender and socioeconomic status led to similar corrections while the ROC analyses were inaccurate.
Conclusions
Using body shape perception, or socioeconomic status and gender is a promising way of correcting BMI in self-administered questionnaires, especially for girls.
doi:10.1371/journal.pone.0096768
PMCID: PMC4028195  PMID: 24844229
21.  Is body mass index (BMI) a useful measure of excess body fatness in adolescents and young adults with Down syndrome? 
Background
To determine the validity of body mass index (BMI) to identify excess fatness in youth with Down syndrome (DS).
Methods
Using the CDC growth reference, we defined overweight (≥85th percentile) and obesity (≥95th percentile) based on participants’ age- and sex-specific BMI z-scores, calculated from measured height and weight. Percentage body fat (%BF) was measured by dual-energy X-ray absorptiometry. We determined sensitivity, specificity, positive predictive value, negative predictive value, and efficiency of BMI percentiles to identify excess adiposity relative to elevated %BF cut-offs developed from the Pediatric Rosetta Body Composition project (Freedman et al., 2009b) in 32 youth (20M/12F), ages 13–21 years with Down syndrome.
Results
For adolescents with Down syndrome using the cut-off points of 95th percentile for BMI (obesity), sensitivity and specificity were 71% and 96%, respectively. Positive predictive value was 83% and negative predictive value was 92%. Overall efficiency was 91%. Sensitivity and specificity for BMI cut-offs above the 85th percentile (overweight) were 100% and 60%, respectively. The positive predictive value was 41% and negative predictive value was 100%. Overall efficiency was 69%.
Conclusion
On the whole, the obesity (≥95th percentile) cut-off performs better than the overweight cut-off (85th–94th percentile) in identifying elevated fatness in youth with DS.
doi:10.1111/j.1365-2788.2012.01605.x
PMCID: PMC4019440  PMID: 22974061
22.  A Study of Insulin Resistance by HOMA-IR and its Cut-off Value to Identify Metabolic Syndrome in Urban Indian Adolescents 
Objective: Insulin resistance (IR) and associated metabolic abnormalities are increasingly being reported in the adolescent population. Cut-off value of homeostasis model of assessment IR (HOMA-IR) as an indicator of metabolic syndrome (MS) in adolescents has not been established. This study aimed to investigate IR by HOMA-IR in urban Indian adolescents and to establish cut-off values of HOMA-IR for defining MS.
Methods: A total of 691 apparently healthy adolescents (295 with normal body mass index (BMI), 205 overweight, and 199 obese) were included in this cross-sectional study. MS in adolescents was defined by International Diabetes Federation (IDF) and Adult Treatment Panel III (ATP III) criteria. IR was calculated using the HOMA model.
Results: Mean height, waist circumference (WC), waist/hip ratio (WHR), waist/height ratio (WHtR), and blood pressure were significantly higher in boys as compared to girls. The HOMA-IR values increased progressively from normal weight to obese adolescents in both sexes. Mean HOMA-IR values increased progressively according to sexual maturity rating in both sexes. HOMA-IR value of 2.5 had a sensitivity of >70% and specificity of >60% for MS. This cut-off identified larger number of adolescents with MS in different BMI categories (19.7% in normal weight, 51.7% in overweight, and 77.0% in obese subjects) as compared to the use of IDF or ATP III criteria for diagnosing MS. Odds ratio for having IR (HOMA-IR of >2.5) was highest with WHtR (4.9, p <0.0001) and WC (4.8, p <0.0001), compared to WHR (3.3, p <0.0001).
Conclusions: In Indian adolescents, HOMA-IR increased with sexual maturity and with progression from normal to obese. A HOMA-IR cut-off of 2.5 provided the maximum sensitivity and specificity in diagnosing MS in both genders as per ATP III and IDF criteria.
Conflict of interest:None declared.
doi:10.4274/Jcrpe.1127
PMCID: PMC3890224  PMID: 24379034
insulin resistance; metabolic syndrome; HOMA-IR; adolescents
23.  Child Nutritional Status: A Representative Survey in a Metropolitan School 
Journal of Obesity  2013;2013:395671.
Objective. To assess the prevalence of obesity, overweight, and thinness among children in an Italian school. Methods. Five hundred ninety-five children (289 males and 306 females) were enrolled, aged between 6 and 19 years old, in Italian school in Rome. Body mass index (BMI) was calculated according to International Obesity Task Force (IOFT) cut-off points. By age criterion all participants have been classified in age classes. Results. A normal BMI was recorded in 73.6% of all cases. Obesity, overweight, and thinness prevalence was 5.9%, 9.6%, and 10.9%, respectively, without statistical differences in both genders, except the prevalence of overweight that resulted statistically significant (13.1% males versus 6.2% females, P < 0.05). Differences in the age groups have been found. About 23.4% of children between 7 to 11 years were defined obese and about 42.3% between 6 to 8 years thin grade 2, respectively. Conclusion. The study reports the low prevalence of overweight and obesity, in contrast to the unexpected thinness prevalence. The identification of specific age groups with abnormal nutritional status could be the first step to address future epidemiological investigations in order to plan strategic approach in selected age periods.
doi:10.1155/2013/395671
PMCID: PMC3568893  PMID: 23431424
24.  Is Waist Circumference A Better Predictor of Diabetes Than Body Mass Index Or Waist-To-Height Ratio In Iranian Adults? 
Background:
Several measures of adiposity have been used for predicting diabetes. The results of studies regarding superiority of waist circumference (WC) to body mass index (BMI) are inconsistent. This study designed to compare the ability of different anthropometric measures in predicting diabetes and to determine their optimal cut-off values.
Methods:
A population-based cross-sectional study was conducted with 1,000 representative sample among adults aged 20–80 years in Babol, the Northern Iran. The demographic data were collected in a household survey, and the anthropometric measures of weight, height, waist, and hip circumference were measured with a standard method. Fasting blood sugar (FBS) ≥126 mg/dl was considered as diabetes. receiver operating characteristic analysis was used to estimate the predictive ability of different anthropometric indexes and their optimal cut-off values for high FBS.
Results:
The overall prevalence rate of diabetes was 14.0% (14.4% in men vs. 13.5% in women, P = 0.65). The prevalence rate was significantly higher in older age (>60 years), low educated and obese (P = 0.001). The mean of BMI, WC, waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR) were significantly higher among diabetic in both sexes (P = 0.001). Among men, WC (area under the ROC curve [AUC] =0.64) and WHtR (AUC = 0.63) have slightly higher accuracy index compared with BMI (AUC = 0.62) or WHR (AUC = 0.60). In contrast, among women, WHtR (AUC = 0.69) and WC (AUC = 0.68) yielded slightly better predictive than BMI (AUC = 0.67). The optimal cut-off values obtained for BMI and WHtR were similar between two sexes (BMI = 24.95 kg/m2 for men and BMI = 25.2 kg/m2 for women, WHtR = 0.51 for both sexes) whereas the optimal cut-off value for WC was higher in men than women (98.5 cm men vs. 89.5 cm women).
Conclusions:
Overall WC and WHtR exhibited a slightly better discriminate performance than BMI for diabetes in both sexes, particularly in women.
doi:10.4103/2008-7802.151434
PMCID: PMC4362276  PMID: 25789140
Body mass index; diabetes; waist circumference; waist-to-height ratio; waist-to-hip ratio
25.  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.
doi:10.4103/0971-5916.93427
PMCID: PMC3307188  PMID: 22382186
BMI; body fat %; new cut-off; overweight

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