Waist circumference, waist-hip ratio and waist-height ratio percentiles and central obesity among Pakistani children aged five to twelve years

Dual burden of body weight among Iranian children and adolescents in 2003 and 2010: the CASPIAN-III study

INTRODUCTION

Our aim was to compare changes of body mass index (BMI) and waist circumference (WC) curves of Iranian children by comparing the results of two national surveys of a surveillance program, i.e. CASPIAN-I (2003-2004) and CASPIAN-III (2009-2010). The second objective was to evaluate the prevalence of obesity, overweight and underweight among 10-18-year-old Iranian children and adolescents.

MATERIAL AND METHODS

This study was performed among students who were selected by multistage random cluster sampling from urban and rural areas of 27 provinces of Iran, as part of a national survey of school student high risk behavior entitled CASPIAN-III, conducted in 2009-2010.

RESULTS

We evaluated 5088 school students (50.2% boys). In rural areas, underweight was more common in boys and overweight and obesity in girls. In urban areas underweight and obesity were more common in boys, whereas overweight was more common in girls. The highest prevalence of underweight (23.5%) was seen in students aged 13 years and the lowest (11.4%) in those aged 18 years. Underweight was significantly more common in rural than in urban areas (22.1% vs. 15.8%, respectively, p < 0.0001) and overweight/obesity was more common in urban than in rural areas. Compared with the findings in 2003-2004, the overall prevalence of elevated body mass index (16.6%) including obesity (9.1%) and overweight (7.5%) as well as underweight (17.5%) increased from 2003 to 2010.

CONCLUSIONS

In recent years, the double burden of nutritional disorders has increased among Iranian children and adolescents, especially in rural areas. This change may be related to epidemiologic transition, notably in terms of nutrition transition and rapid changes in lifestyle habits. This finding is an important issue for policy-makers for interventional preventive programs.

Changing epidemiology of metabolic syndrome and type 2 diabetes in Chinese youth

China is gradually taking its place as one of the world's economic giants and concurrently learning to understand how to bear the burdens of diseases that are more common in the fully developed world, such as pediatric obesity, metabolic syndrome, and type 2 diabetes mellitus. The purpose of this review is to consolidate the available information regarding these and draw the focus toward their sequential progression and increasing prevalence in Chinese children. Studies were collected in both English and Chinese, and the data were reviewed on the basis of disease prevalence and risk factors that are known from scientific literature that has been published to date. The majority of studies with appropriate content for inclusion here have been conducted within the last 15 years and up to date information from recent local and international research has also been included. Several factors have been implicated for the rise in obesity, most notably, the progressing economic expansion and exposure of local Chinese populations to Western influences. With this, metabolic syndrome has become a growing concern, as it is a precursor to cardiovascular disease and type 2 diabetes, leading to the alarmingly rapid development of deleterious consequences in children. The International Diabetes Federation proposed a definition for metabolic syndrome in 2007 (MS-IDF2007) worldwide, but whether it is also suitable for the Chinese population remains uncertain, so we have created the Chinese definition of metabolic syndrome upon the IDF framework. This MS-CHN2012 definition is based on multicenter studies to simplify and standardize primary care screening methods and is the first of its kind in China. Juvenile type 2 diabetes is the most worrisome result of obesity and metabolic syndrome, and studies have shown that the prevalence has doubled within 5 years-surpassing the prevalence of juvenile type 1 diabetes. Because of the extremely low number of studies currently published on these topics in China, emphasis needs to be placed on the assessment of the health status of the population. Screening methods are imperative because lifestyle interventions can reduce and even reverse the pathologic consequences of this disease, if detected early.

Pitfalls of Using Body Mass Index (BMI) in Assessment of Obesity Risk

This review focuses on the potential drawbacks of using body mass index (BMI) which are often overlooked in the assessment of overweight or obesity risk, with special emphasis on the use of other equally important anthropometric measurements such as waist circumference (WC), waist-hip-ratio (WHR) and skin-fold thicknesses. There have been inconsistencies in findings when using BMI as an indicator of obesity risk. These have arisen mainly due to gender, age and ethnic differences in body fat composition and distribution coupled with increased reliance on self-reported values of weight and height. Since BMI remains the most widely used tool to screen obesity risk in many studies, establishment of gender-, age- and ethnicity-based cut-offs of BMI, tailored to specific populations, will significantly enhance public health policies and increase the success rates of obesity intervention programs. The use of other anthropometric measures such as WC and WHR in conjunction with BMI is also highly recommended to assess abdominal obesity or other body-specific areas.

Central obesity in Yemeni children: A population based cross-sectional study

AIM: To establish percentile curves and to explore prevalence and correlates of central obesity among Yemeni children in a population based cross-sectional study.

METHODS: A representative sample of 3114 Yemeni children (1564 boys, 1550 girls) aged 6-19 years participating in the HYpertension and Diabetes in Yemen study was studied. Data collection was conducted at home by survey teams composed of two investigators of both genders. Study questionnaire included questions about demographics, lifestyle, and medical history. Anthropometric measurements included body weight, height, waist circumference (WC) and hip circumferences. Waist to hip ratio (WHR) and waist-to-height ratio (WHtR) were then calculated. Age and gender specific smoothed percentiles of WC, WHR, and WHtR were obtained using lambda-mu-sigma parameters (LMS method). The independent predictors of central obesity defined as (1) WC percentile ≥ 90^th; (2) WHtR ≥ 0.5; or (3) WC percentile ≥ 90^th and WHtR ≥ 0.5, were identified at multivariate logistic regression analysis adjusted for age, gender, urban/rural location, years of school education, sedentary/active life-style.

RESULTS: Percentile curves for WC, WHR and WHtR are presented. Average WC increased with age for both genders. Boys had a higher WC than girls until early adolescence and thereafter girls had higher values than boys. WHR decreased both in boys and girls until early adolescence. Thereafter while in boys it plateaued in girls it continued to decrease. Mean WHtR decreased until early adolescence with no gender related differences and thereafter increased more in girls than in boys towards adult age. Prevalence of central obesity largely varied according to the definition used which was 10.9% for WC ≥ 90^th percentile, 18.3% for WHtR ≥ 0.5, and 8.6% when fulfilling both criteria. At adjusted logistic regression WC ≥ 90^th percentiles and WHtR ≥ 0.5 were less prevalent in rural than in urban areas (OR = 0.52, 95%CI: 0.41-0.67 and 0.66, 0.54-0.79 respectively), being more prevalent in children with sedentary lifestyle rather than an active one (1.52, 95%CI: 1.17-1.98 and 1.42, 95%CI: 1.14-1.75, respectively).

CONCLUSION: Yemeni children central obesity indices percentile curves are presented. Central obesity prevalence varied according to the definition used and was more prevalent in urban sedentary subjects.

Is waist-to-height ratio a useful indicator of cardio-metabolic risk in 6-10-year-old children?

BACKGROUND

Childhood obesity is a public health problem worldwide. Visceral obesity, particularly associated with cardio-metabolic risk, has been assessed by body mass index (BMI) and waist circumference, but both methods use sex-and age-specific percentile tables and are influenced by sexual maturity. Waist-to-height ratio (WHtR) is easier to obtain, does not involve tables and can be used to diagnose visceral obesity, even in normal-weight individuals. This study aims to compare the WHtR to the 2007 World Health Organization (WHO) reference for BMI in screening for the presence of cardio-metabolic and inflammatory risk factors in 6-10-year-old children.

METHODS

A cross-sectional study was undertaken with 175 subjects selected from the Reference Center for the Treatment of Children and Adolescents in Campos, Rio de Janeiro, Brazil. The subjects were classified according to the 2007 WHO standard as normal-weight (BMI z score>-1 and<1) or overweight/obese (BMI z score≥1). Systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting glycemia, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride (TG), Homeostatic Model Assessment--Insulin Resistance (HOMA-IR), leukocyte count and ultrasensitive C-reactive protein (CRP) were also analyzed.

RESULTS

There were significant correlations between WHtR and BMI z score (r=0.88, p<0.0001), SBP (r=0.51, p<0.0001), DBP (r=0.49, p<0.0001), LDL (r=0.25, p<0.0008, HDL (r=-0.28, p<0.0002), TG (r=0.26, p<0.0006), HOMA-IR (r=0.83, p<0.0001) and CRP (r=0.51, p<0.0001). WHtR and BMI areas under the curve were similar for all the cardio-metabolic parameters. A WHtR cut-off value of >0.47 was sensitive for screening insulin resistance and any one of the cardio-metabolic parameters.

CONCLUSIONS

The WHtR was as sensitive as the 2007 WHO BMI in screening for metabolic risk factors in 6-10-year-old children. The public health message "keep your waist to less than half your height" can be effective in reducing cardio-metabolic risk because most of these risk factors are already present at a cut point of WHtR≥0.5. However, as this is the first study to correlate the WHtR with inflammatory markers, we recommend further exploration of the use of WHtR in this age group and other population-based samples.

Body fat distribution of children and adolescents in Abeokuta, Southwest Nigeria

Excessive central fat in children and adolescents is a risk factor for cardiovascular and metabolic disorders. This study aimed to compare the body fat distribution patterns of children and adolescents in Abeokuta, Nigeria with international reference standards. Five hundred seventy children aged 5 to 19 years were selected from seven schools using multistage random sampling. Weight, height, triceps and subscapular skinfold thickness (TSF, SSF), and circumference at the waist and hips (WC, HC) were measured. Body mass index (BMI), subscapular:triceps skinfold ratio (STR), waist:hip circumference ratio (WHR), and waist: height ratio (WHtR) were derived. Females had higher mean BMI, TSF, SSF, WC, HC, WHR, and WHtR, while males had significantly higher STR. The mean BMI, WC, TSF, and SSF values were lower for our subjects than for African-American subjects at all ages. On the other hand, in both sexes, STR was higher among Nigerian than African-American subjects up to 12 years old. Thereafter the values were similar. The mean WC was similar to those reported for African-American males up to 8 years, and females up to 7 years of age; thereafter, African-American had higher values. The prevalence of central obesity using WC and WHtR measures was 4.4% and 5.8%, respectively. There is a need to validate each index against serum lipid profiles and other cardiovascular and metabolic risk factors.

Antioxidant enzymes activities in obese Tunisian children

Background

The oxidant stress, expected to increase in obese adults, has an important role in the pathogenesis of many diseases. It results when free radical formation is greatly increased or protective antioxidant mechanisms are compromised. The main objective of this study is to evaluate the antioxidant response to obesity-related stress in healthy children.

Methods

A hundred and six healthy children (54 obese and 52 controls), aged 6–12 years old, participated in this study. The collected data included anthropometric measures, blood pressure, fasting glucose, total cholesterol, triglycerides and enzymatic antioxidants (Superoxide dismutase: SOD, Catalase: CAT and Glutathione peroxidase: GPx).

Results

The first step antioxidant response, estimated by the SOD activity, was significantly higher in obese children compared with normal-weight controls (p < 0.05). Mean activities of anti-radical GPx and CAT enzymes were not affected by the BMI increase. Although, total cholesterol levels were statistically higher in the obese group, there was no significant association with the SOD activity.

Conclusions

The obesity-related increase of the oxidant stress can be observed even in the childhood period. In addition to the complications of an increased BMI, obesity itself can be considered as an independent risk factor of free radical production resulting in an increased antioxidant response.

Waist circumference percentiles among Turkish children under the age of 6 years

Waist circumference, a proxy measure of abdominal obesity, is associated with cardio-metabolic risk factors in childhood and adolescence. Although there are numerous studies about waist circumference percentiles in children, only a few studies cover preschool children. The aim of this study was to develop age- and gender-specific waist circumference smoothed reference curves in Turkish preschool children to determine abdominal obesity prevalence and to compare them with reference curves obtained from different countries. The design of the study was cross-sectional. A total of 2,947 children (1,471 boys and 1,476 girls) aged 0-6 years were included in the study. The subjects were divided according to their gender. Waist circumference was measured by using a standardized procedure. The age- and gender-specific waist circumference reference curves were constructed and smoothed with LMS method. The reference values of waist circumference, including 3rd, 10th 25th, 50th, 75th, 90th, and 97th percentiles, and standard deviations were given for preschool children. Waist circumference values increased with age, and there were differences between genders. The prevalence of abdominal obesity was calculated as 10.1 % for boys and 10.7 % for girls. Having compared our data with two other countries' data, we found that our waist circumference data were significantly lower. This is the first cross-sectional study for age- and gender-specific references of 0- to 6-year-old Turkish children. The gender- and age-specific waist circumference percentiles can be used to determine the risk of central obesity.