Obesity: diagnosis, prevention, and treatment; evidence based answers to common questions

Validation of mid-arm circumference for surveillance of obesity in African adolescent girls and adult women

This study aimed to assess the validity of mid-arm circumference (MAC), also known as mid-upper arm circumference (MUAC), for classification of high body fatness in Namibian adolescent girls and women and to test whether classification accuracy of MUAC was higher than the traditional simple proxy for high fatness, the BMI. In 206 adolescent girls aged 13-19 years and 207 adult women aged 20-40 years, we defined obesity conventionally (BMI-for-age Z score ≥ 2·00, adolescents; adults BMI ≥ 30·0 kg/m2) and also defined obesity using published MAC cut-off values. 2H oxide dilution was used to measure total body water (TBW) to define high body fat percentage (≥ 30 % in the adolescents, ≥ 38 % in the adults), and we compared the ability of BMI and MAC to classify high body fatness correctly using sensitivity, specificity and predictive values. In the adolescents, obesity prevalence was 9·2 % (19/206) using BMI-for-age and 63·2 % (131/206) using TBW; sensitivity of BMI-for-age was 14·5 % (95 % CI 9·1, 22·0 %) but was improved significantly using MAC of 22·6 cm (sensitivity 96·9 %; 95 % CI 92·1 %, 99·3 %). In the adults, obesity prevalence was 30·4 % (63/207) using BMI and 57·0 % (118/207) using TBW, and sensitivity of BMI was 52·5 % (95 % CI 43·6, 62·2 %), but using a MAC of 30·6 cm sensitivity was 72·8 % (95 % CI 66·4, 82·6 %). Surveillance of obesity in African adolescent girls and adult women is likely to be improved substantially by use of MAC as an alternative to the BMI-for-age and BMI.

Mediators of the association between childhood body mass index and educational attainment: Analysis of a UK prospective cohort study

BACKGROUND

Higher body mass index (BMI) in childhood is associated with lower academic achievement.

OBJECTIVE

To explore potential pathways linking childhood BMI with educational attainment.

METHODS

Using data from the Avon Longitudinal Study of Parents and Children prospective cohort study (N = 6949), we assessed the association between BMI z-scores at 11.7 years and educational attainment at 16 (General Certificate of Secondary Education [GCSE] results). Depressive symptoms, externalizing behaviours, bullying and school enjoyment were considered as potential mediators. Mediators were examined individually and jointly using sequential causal mediation.

RESULTS

Higher BMI z-scores were associated with lower GCSE scores (females β = -3.47 95% CI -5.54, -1.41 males β = -4.33 95% CI -6.73, -1.94). Together, bullying, externalizing symptoms, depressive symptoms and school enjoyment mediated 41.9% of this association in females, and 23.3% in males. In males, evidence for mediation was weak (confidence intervals for all indirect effects spanned the null). In both females and males, most of the mediation was driven by externalizing symptoms.

CONCLUSIONS

The detrimental effect of higher BMI on educational attainment appears to be partly explained by externalizing behaviours, particularly in females. Interventions to support behavioural problems may help the academic achievement of children with a higher body weight.

Relationship between Slip Severity and BMI in Patients with Slipped Capital Femoral Epiphysis Treated with In Situ Screw Fixation

Background: Slipped capital femoral epiphysis (SCFE) is a hip disorder that occurs in adolescence before epiphyseal plate closure, causing anatomical changes in the femoral head. Obesity is known to be the single most important risk factor for idiopathic slipped capital femoral epiphysis (SCFE), which is highly related to mechanical factors. Meanwhile, as increased slip angle increases major complications in patients with SCFE, slip severity is an important factor to evaluate prognosis. In obese patients with SCFE, higher shear stress is loaded on the joint, which increases the likelihood of slip. The study aim was to assess the patients with SCFE treated with in situ screw fixation according to the degree of the obesity and to find any factors affecting the severity of slip. Methods: Overall, 68 patients (74 hips) with SCFE who were treated with in situ fixation screw fixation were included (mean age 11.38, range: 6–16) years. There were 53 males (77.9%) and 15 females (22.1%). Patients were categorized underweight, normal weight, overweight, and obese depending on BMI percentile for age. We determined slip severity of patients using the Southwick angle. The slip severity was defined as mild if the angle difference was less than 30 degrees, moderate if the angle difference was between 30 and 50 degrees, and severe if the angle difference was greater than 50 degrees. To examine the effects of several variables on slip severity, we used a univariable and multivariate regression analysis. The following data were analyzed: age at surgery, sex, BMI, symptom duration before diagnosis (acute, chronic, and acute on chronic), stability, and ability to ambulate at the time of the hospital visit. Results: The mean BMI was 25.18 (range: 14.7–33.4) kg/m2. There were more patients with overweight and obese than those with normal weight in SCFE (81.1% vs. 18.9%). We did not find significant differences between overall slip severity and degree of obesity or in any subgroup analysis. Conclusions: We did not find a relationship between slip severity and degree of obesity. A prospective study related to the mechanical factors affecting the slip severity according to the degree of obesity is needed.

Objectively Measured Physical Activity and Sedentary Time of Suburban Toddlers Aged 12-36 Months

Low levels of physical activity may predispose children to the development of obesity and related chronic diseases in later life. The aims of this study were as follows: (1) quantitatively describe the levels of habitual physical activity in a contemporary sample of suburban children aged 12 to 36 months; (2) assess for gender differences in physical activity and sedentary behavior; (3) examine the specific effects of ethnicity, gender and overweight status on the objectively measured physical activity; and (4) quantify the tracking of physical activity in a subset of children over 1 year. During year one, 142 participants wore the GT3X Actigraph for 3 days. At a 1-year follow-up, a subset of 25 participants wore the Actigraph for 7 consecutive days. GLM and t-tests as appropriate were carried out to assess the influence of gender on the physical activity level. Spearman rank correlations, percentage agreement and kappa statistics assessed the tracking of physical activity. The results showed no significant gender differences in any anthropometric measurements, sedentary behavior or MVPA (p > 0.05). There were also no significant gender, ethnicity or overweight interaction for sedentary behavior, time spent in light PA and time spent in MVPA (p > 0.05). For tracking, there was a moderate strength of agreement for MVPA. Considering the disproportionate effects of obesity in minority groups, culturally appropriate interventions targeting the reduction in sedentary behavior are urgently required.

10-Year Changes in Adiposity in Cameroon School-Age Children: Evidence for Increasing Central Adiposity and Higher Adiposity Levels in Tallest-for-Age Children

OBJECTIVE

To examine changes in measures of adiposity and determine the prevalence of excess adiposity in relation to height in school children between 2010 and 2020.

METHODS

5-12-year-old urban school-age children participated in two cross-sectional surveys in 2010 (n = 1274) and 2020 (n = 1550). Standard procedures were used for anthropometric measurements. Changes in BMI, waist circumference (WC), and waist-to-height ratio (WHtR) and the corresponding proportions of children with excess adiposity were analyzed and adjusted for design variables (class and school type) and age. Children were classified according to quartiles of height z-score and prevalence of excess adiposity estimated across each quartile.

RESULTS

There was a 2.4% and 3.3% increase in adjusted mean BMI and WC, respectively, between 2010 and 2020. The prevalence of central overweight/obesity (WC) and WHtR ≥ 0.5 increased by 7.3% (X ² = 27.151, p < 0.001) and 5.3% (X ² = 26.117, p < 0.001), respectively, between the two surveys except BMI overweight/obesity. The odds of excess adiposity significantly increased in 2020 for central overweight/obesity (WC) (OR 2.8, 95% CI 2.0-3.6) and WHtR ≥ 0.5 (OR 1.8, 95% CI 1.3-2.4) and not for BMI overweight/obesity (OR 1.3, 95% CI 0.8-1.7). The prevalence of BMI overweight/obesity significantly increased from 33% in 2010 to 51.5% in 2020 in the fourth quartile of height z-score (X ² = 19.198, p < 0.001). Similarly, the prevalence of central overweight/obesity (WC) significantly increased from 23.5% in 2010 to 42.4% in 2020 in the fourth quartile of height z-score (X ² = 18.733, p < 0.001).

CONCLUSION

Central overweight/obesity has increased more than BMI overweight/obesity over the last decade. Children with a higher height-for-age tend to accumulate more adiposity. Objective monitoring of adiposity levels and height of children is needed in future to identify groups for targeted intervention and prevention of chronic diseases.

Are the Growth Standards of the World Health Organization Valid for Spanish Children? The SONEV Study

Background: The use of different growth tables to assess the population's nutritional status has given rise to a series of limitations arising from the lack of consensus and uniform methodological criteria. This leads to a disparity of results that prevent an accurate and reliable diagnosis of whether a child is overweight or obese. Objective: The purpose of this study was to develop growth references for weight, height, and body mass index for Eastern-Spanish children from 6 to 16 years of age. Methods: The final sample used to fit the growth curves was made up of 1,102 observations. The 2007 WHO curves are currently used for Child Health Service Cards. Therefore, to make the comparison of the internal values obtained as realistic as possible, the same construction method has been used for the internal curves, modeling age as a continuous variable and simultaneously adjusting the curves, smoothing them using cubic splines and further smoothing the edge effects by means of data extending above or below the upper and lower age limits. Results: Growth curves for percentiles were constructed for both sexes and higher values were noticeably found to set as growth-standard compared to WHO-standards. Conclusion: Our analysis shows that the WHO 2007 standard references are not suitable for Eastern-Spanish children. The standards shown in this study are much more realistic and current, and we believe that their use will help healthcare professionals more effectively combat the current epidemic of overweight and obesity.

Body mass index vs deuterium dilution method for establishing childhood obesity prevalence, Ghana, Kenya, Mauritius, Morocco, Namibia, Senegal, Tunisia and United Republic of Tanzania

Objective

To compare the World Health Organization (WHO) body mass index (BMI)-for-age definition of obesity against measured body fatness in African children.

Methods

In a prospective multicentre study over 2013 to 2017, we recruited 1516 participants aged 8 to 11 years old from urban areas of eight countries (Ghana, Kenya, Mauritius, Morocco, Namibia, Senegal, Tunisia and United Republic of Tanzania). We measured height and weight and calculated BMI-for-age using WHO standards. We measured body fatness using the deuterium dilution method and defined excessive body fat percentage as > 25% in boys and > 30% in girls. We calculated the sensitivity and specificity of BMI z-score > +2.00 standard deviations (SD) and used receiver operating characteristic analysis and the Youden index to determine the optimal BMI z-score cut-off for classifying excessive fatness.

Findings

The prevalence of excessive fatness was over three times higher than BMI-for-age-defined obesity: 29.1% (95% CI: 26.8 to 31.4; 441 children) versus 8.8% (95% CI: 7.5 to 10.4; 134 children). The sensitivity of BMI z-score > +2.00 SD was low (29.7%, 95% CI: 25.5 to 34.2) and specificity was high (99.7%, 95% CI: 99.2 to 99.9). The receiver operating characteristic analysis found that a BMI z-score +0.58 SD would optimize sensitivity, and at this cut-off the area under the curve was 0.86, sensitivity 71.9% (95% CI: 67.4 to 76.0) and specificity 91.1% (95% CI: 89.2 to 92.7).

Conclusion

While BMI remains a practical tool for obesity surveillance, it underestimates excessive fatness and this should be considered when planning future African responses to the childhood obesity pandemic.

Measuring Abdominal Visceral Fat Thickness With Sonography: A Methodologic Approach

This methodological approach to assessing obesity is based on the prepilot work conducted on a small sample of men and women (25-58 years of age) in a laboratory setting. The use of skinfold calipers, body mass index, and sonographic imaging of adipose and visceral fat were obtained. In this pre-experimental work, the rigorous use of sonographic measures of visceral fat demonstrated better trend results than the other measurement tools. The sonographic methods employed were modeled after the work published by Hamagawa et al. All measurements were taken five times, and only the middle three were retained for mean data points. The data are compared and contrasted with a paucity of international studies using sonography to measure visceral adiposity. It is important to determine whether sonography could serve as a non-ionizing imaging technique for the assessment of body composition and a screening technique for cardiovascular disease prediction.

Inflammatory Biomarkers of Cardiometabolic Risk in Obese Egyptian Type 2 Diabetics

Inflammatory biomarkers provide a minimally invasive means for early detection and specific treatment of metabolic syndrome and related disorders. The objective of this work was to search for inflammatory biomarkers of cardiometabolic risk in obese type 2 diabetics. The study was performed on 165 persons attending the medical outpatient clinic of Ismailia General Hospital. Their mean age was (50.69 ± 10.15) years. They were divided into three groups. The control group was composed of 55 non-obese, non-diabetic healthy volunteers, 32 males and 23 females. Two study groups were included in this study: group 2 was composed of 55 obese, non-diabetic subjects, 25 males and 30 females matched for age and gender. All patients including the control were subjected to clinical history taking, a clinical examination for the measurement of body mass index (BMI). Investigations were carried out for fasting blood glucose, fasting serum insulin, insulin resistance (IR), the lipid profile, lipoprotein band lipoprotein phospholipase A2, and non-high-density lipoprotein cholesterol (non-HDL-C). Urea, albumin and creatinine analysis and liver function tests were performed, and a complete blood count (CBC) was taken. Hemoglobin A1C (HbA1C), serum high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were tested. There were statistically significant differences among the studied groups in terms of total cholesterol, non-HDL-C, high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), lipoprotein-associated phospholipase A2 and apolipoprotein B. The inflammatory biomarkers hs-CRP, IL-6 and TNF-α were significantly statistically increased in the study groups by (1.62 ± 0.99, 2.32 ± 1.11), (1.73 ± 1.14, 2.53 ± 1.34), and (1.87 ± 1.09, 2.17 ± 0.89) respectively, where p < 0.01. Significant positive correlation was found between Homeostatic Model Assessment (HOMA)-IR, hs-CRP and IL-6. There was a significant positive correlation between non-HDL and hs-CRP, IL-6 and TNF-α and triglycerides and hs-CRP. In conclusion, in this study, CRP, IL-6, and TNF-α were significantly elevated in obese Egyptian type 2 diabetics and were positively correlated with insulin resistance, non-HDL and triglycerides. These inflammatory biomarkers could help in the premature identification of obese type 2 diabetic patients at high cardiometabolic risk. Additionally, these biomarkers are critical for providing prognostics and the validity of future potential anti-inflammatory therapeutic modalities.

Exploring overweight and obesity in pre-school children using routinely collected data: a case study of Halton, Northwest England

BACKGROUND

A growing body of evidence suggests that childhood overweight may have its roots in early life. This study aimed to explore patterns of weight in children from birth to 40 months, born between 1994 and 2006, in Halton, Northwest England.

METHODS

Halton infants were compared with the UK-90 reference population at four time points (birth, 2 months, 8 months and 40 months) by converting heights and weights into age-sex adjusted SD scores. The mean and SD of Halton SD scores were calculated for each time point and sex. Cohort trends and gender differences in rates of children above the 85th and 95th centiles at each time point were tested for using Poisson regression modelling.

RESULTS

A total of 16 381 births were analysed. At birth, 8 months and 40 months, proportions of Halton children above the 85th and 95th centiles were consistently higher than reference data. Proportions above the 85th and 95th centiles at birth did not change significantly year on year, but for all other time points the proportions increased with subsequent cohorts.

CONCLUSIONS

This study may provide evidence that the development of overweight and obesity has its roots in very early life and has highlighted patterns of infant overweight and obesity not previously reported.

[Physical fitness reference tables for females in the 10 to 14 age range in Chillán (Chile)]

Objective To develop physical fitness reference tables oriented towards the health of female students in the 10 to 14 year age range, in Chillán, Chile. Method The present is a cross-sectional study. The sample is composed of 250 female students in the 10 to 14 year age range. To evaluate health-related physical fitness, the following tests were used: Body mass index (BMI), Deurengerg Formula (Body fat %), Wells and Dillon's Bench (Flexibility), Sargent Jump Test (lower limbs strength, 1 Mile Test (endurance) and the 30 Seconds Sit Up Test (focalized muscular endurance). Descriptive statistics were used to develop the reference tables. From the results, 5 categories were made: very bad, bad, regular, good, and very good. Age was used as a parameter. Results This study demonstrates the low level of fitness capacity of the group evaluated when compared to national and international references. It shows low levels of cardiorespiratory endurance, strength of lower limbs, flexibility, and focalized muscular endurance. The present study also shows that being overweight is associated with low cardiorespiratory capacity, and that there was a high prevalence of this in the sample compared to the national level of overweight and obesity in females in the 10-14 age range. Conclusion The tests applied in the present study are a reliable and simple tool for assessing the level of health-related fitness capacity. They can be applied in any educational institution, since a large or complex infrastructure for its application is not required.

Height-obesity relationship in school children in Sub-Saharan Africa: results of a cross-sectional study in Cameroon

BACKGROUND

In developed nations, taller children exhibit a greater propensity to overweight/obesity. This study investigates whether this height-adiposity relationship holds true for Cameroon children using two parameters of adiposity including body mass index (BMI) and waist circumference (WC).

METHODS

In 557 children (287 boys and 270 girls, mean age 9.0 ± 1.8 years) from the North West Region of Cameroon height, weight and WC were measured and BMI calculated. Variables were converted to standard deviation scores (SDS). Participants were divided into quartiles of height SDS, then mean of age and sex-standardized body fat parameters compared across quartiles. The frequency of excess adiposity was calculated within each quartile. Correlation and regression analysis were used to assess height-adiposity relationships.

RESULTS

Multiple comparisons indicated a significant increase in mean BMI (-0.08 to 0.65) and WC (-0.11 to 0.87) SDSs with increasing quartiles of height SDS. Frequency of overweight/obesity and abdominal overweight/obesity was highest among children with highest height SDS (30.2 - 33.1%) and lowest in their shortest peers (0.7 - 5.0%). There was a linear relationship between height SDS and BMI SDS (R(2) = 0.087, p < 0.001); height SDS and WC SDS (R(2) = 0.356, p < 0.001) among both boys and girls.

CONCLUSIONS

This study shows that in Cameroon just as in developed economies a higher height SDS is associated with a higher frequency of overweight/obesity. This is independent of the parameter used to evaluate overweight/obesity (BMI SDS or WC SDS).

Obesity impairs academic attainment in adolescence: findings from ALSPAC, a UK cohort

OBJECTIVE

While being overweight or obese in adolescence may have detrimental effects on academic attainment, the evidence base is limited by reliance on cross-sectional studies with small sample sizes, failure to take account of confounders and lack of consideration of potential mediators. The present study aimed to address these limitations and examine longitudinal associations between obesity in adolescence and academic attainment.

DESIGN

Associations between weight status at 11 years old and academic attainment assessed by national tests at 11, 13 and 16 years were examined in the Avon Longitudinal Study of Parents and Children. Healthy weight was defined as body mass index (BMI) Z-score <1.04; overweight as BMI Z-score 1.04-1.63; obesity as BMI Z-score ⩾1.64.

PARTICIPANTS

Data from 5966 participants with objectively measured weight status were examined: 71.4% were healthy weight (1935 males; 2325 females), 13.3% overweight (372 males; 420 females) and 15.3% obese (448 males; 466 females).

RESULTS

Girls obese at 11 years had lower academic attainment at 11, 13 and 16 years compared with those of a healthy weight, even after controlling for a wide range of confounders. Associations between obesity and academic attainment were less clear in boys. The potential mediating effects of depressive symptoms, intelligence quotient (IQ) and age of menarche in girls were explored, but when confounders were included, there was no strong evidence for mediation.

CONCLUSIONS

For girls, obesity in adolescence has a detrimental impact on academic attainment 5 years later. Mental health, IQ and age of menarche did not mediate this relationship, suggesting that further work is required to understand the underlying mechanisms. Parents, education and public health policy makers should consider the wide reaching detrimental impact of obesity on educational outcomes in this age group.

Use of mid-upper arm circumference for determining overweight and overfatness in children and adolescents

OBJECTIVE

To assess the use of mid-upper arm circumference (MUAC) for identification of overweight and overfatness in rural South African children and adolescents.

METHODS

Anthropometric data (weight, height, MUAC and % body fat) from a cross-sectional sample of 978 black South African 5-14-year-olds were analysed. Receiver operating characteristic (ROC) curve analysis determined the validity of MUAC as a proxy for determining overweight and overfatness.

FINDINGS

Area under the curve (AUC) results were generally high. Boys and girls aged 10-14 years had ROC-AUC for overfatness classed as 'excellent', 0.97 and 0.98 respectively. Cut-points in the MUAC distribution which optimised the ROC-AUC for identification of overfatness and obesity were determined for boys and girls aged 5-9 and 10-14 years, and had high sensitivity and specificity.

CONCLUSIONS

MUAC may have potential for clinical and surveillance applications as an accurate yet simple and widely available indicator of overweight and overfatness in children and adolescents in resource-poor settings.

The preliminary effects of a primary care-based randomized treatment trial with overweight and obese young children and their parents

INTRODUCTION

Twenty-three percent of preschoolers are overweight/obese, which puts these children at risk for the development of chronic health comorbidities. The purpose of this randomized control pilot study was to determine the feasibility and preliminary effects of a theoretically based, primary care intervention on the physical outcomes of 60 overweight/obese preschool/early school-aged 4- to 8-year-old children.

METHODS

After recruitment and baseline assessment, parent-child dyads were randomly assigned to either the treatment or the control condition. Four intervention sessions were conducted with the parents in their child's primary health care office. The impact of the intervention was evaluated by assessing child anthropometric measures (e.g., waist, waist-by-height ratio, and body mass index [BMI]) immediately, 3 months, and 6 months after the intervention period.

RESULTS

Analysis of variance models suggested that children in the experimental group were found to have reduced waist circumference and waist-by-height ratio immediately after the intervention that persisted for 3 and 6 months (f = 0.33, 0.35, respectively). BMI and BMI percentile were not differentially affected.

DISCUSSION

These promising findings suggest that a primary care-based, parent-focused overweight/obesity treatment program is feasible and demonstrated positive preliminary effects, improving the children's overall health trajectory.

An Objective Method for Measurement of Sedentary Behavior in 3- to 4-Year Olds

OBJECTIVE

To test the ability of accelerometry to quantify sedentary behavior in 3- to 4-year-old children.

RESEARCH METHODS AND PROCEDURES

We developed a cut-off for accelerometry output (validation study) in 30 healthy 3 to 4 year olds, which provided highest sensitivity and specificity for the detection of sedentary behavior relative to a criterion method of measurement, direct observation using the children's physical activity form. We then cross-validated the cut-off in an independent sample of healthy 3 to 4 year olds (n = 52).

RESULTS

In the validation study, optimal sensitivity and specificity for the detection of sedentary behavior were obtained at an accelerometry output cut-off of <1100 counts/min. In the cross-validation, sensitivity was 83%: 438/528 inactive minutes were correctly classified. Specificity was 82%: 1251/1526 noninactive minutes were correctly classified using this cut-off.

DISCUSSION

Sedentary behavior can be quantified objectively in young children using accelerometry. This new technique could be considered for a wide variety of applications in the etiology, prevention, and treatment of childhood obesity.

Cross-sectional comparisons of BMI and waist circumference in British children: mixed public health messages

Research suggests that there has been a leveling off in obesity prevalence occurring in the child population. However, a concern with the evidence base is that all of the studies have relied upon the use of BMI. The purpose of this study was to compare waist circumference (WC), BMI, and waist-to-height ratio (WHtR) data in three different sample of children (total number: 14,697) typically aged 11-12 years. Obesity prevalence defined by BMI did not change significantly between measurement years (2005 boys 20.6%, girls 18.0%; 2006 boys 19.3%, girls 17.3%; 2007 boys 19.8%, girls 16.4%). Obesity prevalence defined by WC was considerably higher especially, in girls (2005 boys 26.3%, girls 35.6%; 2006 boys 20.3%, girls 28.2%; 2007 boys 22.1%, girls 30.1%). The prevalence of children defined as "at risk" according to WHtR (2005 boys 23.3%, girls 21.1%; 2006 boys 16.7%, girls 15.6%; 2007 boys 17.6%, girls 17.2%) was found to be between obesity prevalence, estimated using BMI and WC. This data are the most up to date collection that includes BMI and WC in three large samples of children and clearly demonstrates inconsistencies between different measurements based on current classification systems. There is a need to understand the relationship between BMI and WC, with growth and health risk to establish a consistent public health message that is easily understood by the public.

Prevalence of Underweight, Overweight and Obesity Among Primary School Children in Qatar

A cross-sectional stratified cluster sample of 4291 children (2187 boys and 2104 girls) aged 6 to18 years attending primary public schools in Qatar was used to determine the prevalence of underweight, overweight and obesity among primary school children in Qatar using BMI as an indicator. Structured questionnaires were used to obtain socio-demographic data. Anthropometric measures were taken by trained nurse. The study revealed a high prevalence of underweight and obesity among Qatari children, with both conditions implicating adverse short and long-term health effects. The prevalence of underweight (BMI <  5% of CDC standard for ageand sex) was 14.6%, overweight (BMI 85% to 95%) was 11.6% and obesity (BMI > 95%) was 14.7% (95% confidence level). The prevalence of overweight and obesity was higher in girls (28.7%) than boys (24%) but was similar in Qatari (26.4%) and non-Qatari children (26.2%). The prevalence of both underweight (15.6%) and obesity (15.8%) were considerably higher in Qatari children.

Relationship of objective measurement of physical activity during school hours and BMI in preschool children

The measurement of the physical activity (PA) since early ages is a key factor in lifestyle evaluation. The aims of this study were to describe objective levels of PA and to determine the association of body mass index status (BMI) with PA patterns in preschool children. Weight and height were measured in 59 healthy pre-school children. The children used the accelerometer for 4 consecutive days during school hours. The prevalence of OW+OB was 30.5%. The 82.31% of the time spent at kindergarten was allocated to sedentary tasks. The 5 years-old boys were significantly more engaged in TPA and MVPA and less in SB than girls. No statistically significant associations were found between OW/OB and PA patterns. Most of the time spent at school is related to SB, which is central to childhood obesity risk. Early interventions to increase PA in preschool children are needed.

Influence of contextual and individual level risk factors on adiposity in a preschool child cohort in Ho Chi Minh City, Vietnam

OBJECTIVE

To identify risk factors associated with changes in BMI and sum of skinfold thickness (SSF) in a cohort of preschool children in Ho Chi Minh City (HCMC), Vietnam.

METHODS

This one year follow-up study, using multi-stage cluster sampling, was conducted from 2005-2006 with 526 children aged 4-5 years in preschools in urban HCMC. Information on neighborhood, preschool and home environments, socio-economic status, the child and parental characteristics were collected using interview-administered questionnaires. Dietary intake and physical activity were measured using modified, validated questionnaires. Weight, height, and triceps, subscapular and suprailiac skinfold thickness were measured. Generalized estimating equations (GEEs) were used to assess the longitudinal relationships between the risk factors and the development of adiposity.

RESULTS

A variety of factors at different levels were associated with changes in BMI and SSFs. As safety of the neighborhood increased, BMI and SSFs decreased (coefficients for BMI: -0.59; 95% CI: -1.16 to -0.01 for girls and -0.80; 95% CI: -1.53, -0.08 for boys, and coefficients for SSFs: -2.71; 95% CI: -5.07, -0.35 for girls and -4.16, 95% CI: -8.28, -0.05). Having both parents overweight was strongly predictive of an increase in BMI (1.18, 0.21-2.16). Maternal pre-pregnant BMI status, breast-feeding, and high birth weight were also related to change in adiposity.

CONCLUSION

Contextual variables in the community and home environment, and parental characteristics appeared to be more important than individual factors for explaining on changes in adiposity in this child population.

Underweight and overweight in primary school children in eThekwini district in KwaZulu-Natal, South Africa

Background: The prevalence of overweight and obesity in children has been increasing worldwide. South Africa has minimal data on childhood body weight.Objectives: This study determined whether school children in the eThekwini district in KwaZulu-Natal, South Africa, were underweight or overweight.Method: A survey with quantitative and qualitative components was conducted amongst 120 participants between 10 years and 12 years of age. The participants were randomly selected from six public schools in an urban district of the province. A calibrated Goldline bathroom scale was used to measure body weight and a KDS Freo non-elastic measuring tape was used to measure height. A questionnaire consisting of open and close-ended questions collected demographic and lifestyle information. Body mass index (BMI) was calculated from height and weight data. Proportions of obese, overweight and underweight children were calculated and subjected to chi-square tests at the p ≤ 0.05 significance level. All qualitative information was summarised.Results: According to World Health Organization criteria, 66% of the children were underweight, 28% were of normal weight and 5% were overweight. The proportion of underweight children increased with age (64% of children aged between 10 years and 11 years vs 70% for 12-year-olds). Of the underweight children, 41% were female and 51% were Indian.Only one child was obese. BMI was related to dietary patterns and activity levels during and outside school hours.Conclusion: A significant number of primary school children from the six selected public schools in the eThekwini district were underweight. More effort is required to improve the nutritional status of school children in the eThekwini district.

Effect of stride frequency on the energy cost of walking in obese teenagers

The aim of this study was to compare the energy cost of obese and non-obese teenagers while walking at their preferred speed and different stride frequencies. Twelve obese and twelve non-obese teenagers walked continuously on the treadmill at their most comfortable speed for 6 periods of 4 min each. Each period corresponded to a specific stride frequency: preferred (PSF), force-driven harmonic oscillator (FDHO), PSF+10%, PSF+20%, PSF-10% and PSF-20%. Cardiorespiratory parameters were collected between the 3rd and 4th minute of each stage, and used to calculate the energy cost of walking (EC). The main results showed a significantly higher cost of walking expressed relative to lean body mass. In addition, a U-shaped relationship between EC and stride frequency was shown in both groups, with PSF and FDHO leading to a significantly lower value compared to all other frequencies. This showed first, that FDHO is a good predictor of PSF and minimal energy cost of walking in both groups, and second, that excess body fat does not affect the relationship between energy expenditure and stride frequency. Walking at lower or higher than preferred frequencies could be used as an exercise mode to promote weight loss in obese teenagers.

Accuracy of simple clinical and epidemiological definitions of childhood obesity: systematic review and evidence appraisal

The optimum means of defining obesity in children is unclear, creating variation in practice, and hindering obesity surveillance, prevention and treatment. This study aimed to review evidence on the use of body mass index (BMI) and waist circumference for diagnosis of high body fat content and adverse cardiometabolic risk factors in children and adolescents. A systematic literature review was carried out and evidence appraised using the Quality Assessment of Studies of Diagnostic Accuracy in Systematic Reviews method. Literature searching began following the last systematic review of this topic (end 2001) and collected evidence in MEDLINE and EMBASE in 0- to 18-year-olds that compared the accuracy of BMI vs. waist circumference and compared BMI interpreted relative to national reference data vs. BMI interpreted relative to Cole/International Obesity Task Force international reference data. Ten studies compared diagnostic accuracy of BMI vs. waist circumference: they reported no improved identification of adverse cardiometabolic risk profiles from waist circumference over that provided by high BMI. Eight studies compared BMI with national reference data vs. the international approach: 5/8 found significantly poorer accuracy (lower sensitivity) using BMI with the international approach; 3/8 found similar sensitivity; in 7/7 studies that compared specificity this was similar. In conclusion, the present review provides no compelling evidence for use of either high waist circumference or BMI interpreted using the International Obesity Task Force approach in preference to the use of national BMI percentiles for the identification of children and adolescents with excess fatness and adverse cardiometabolic risk profile.

Assessing weight perception accuracy to promote weight loss among U.S. female adolescents: a secondary analysis

BACKGROUND

Overweight and obesity have become a global epidemic. The prevalence of overweight and obesity among U.S. adolescents has almost tripled in the last 30 years. Results from recent systematic reviews demonstrate that no single, particular intervention or strategy successfully assists overweight or obese adolescents in losing weight. An understanding of factors that influence healthy weight-loss behaviors among overweight and obese female adolescents promotes effective, multi-component weight-loss interventions. There is limited evidence demonstrating associations between demographic variables, body-mass index, and weight perception among female adolescents trying to lose weight. There is also a lack of previous studies examining the association of the accuracy of female adolescents' weight perception with their efforts to lose weight. This study, therefore, examined the associations of body-mass index, weight perception, and weight-perception accuracy with trying to lose weight and engaging in exercise as a weight-loss method among a representative sample of U.S. female adolescents.

METHODS

A nonexperimental, descriptive, comparative secondary analysis design was conducted using data from Wave II (1996) of the National Longitudinal Study of Adolescent Health (Add Health). Data representative of U.S. female adolescents (N = 2216) were analyzed using STATA statistical software. Descriptive statistics and survey weight logistic regression were performed to determine if demographic and independent (body-mass index, weight perception, and weight perception accuracy) variables were associated with trying to lose weight and engaging in exercise as a weight-loss method.

RESULTS

Age, Black or African American race, body-mass index, weight perception, and weight perceptions accuracy were consistently associated with the likeliness of trying to lose weight among U.S. female adolescents. Age, body-mass index, weight perception, and weight-perception accuracy were positively associated (p < 0.05) with trying to lose weight. Black/African American subjects were significantly less likely than their White counterparts to be trying to lose weight. There was no association between demographic or independent variables and engaging in exercise as a weight-loss method.

CONCLUSIONS

Findings suggest that factors influencing weight-loss efforts, including age, race, body-mass index, weight perception, and weight-perception accuracy, should be incorporated into existing or new multi-component weight-loss interventions for U.S. adolescent females in order to help reduce the national epidemic of overweight and obesity among U.S. female adolescents.

Assessment of obesity in children and adolescents: synthesis of recent systematic reviews and clinical guidelines

This review summarises recent systematic reviews and evidence-based guidelines that deal with the issue of how best to diagnose or define obesity in children and adolescents. A recent systematic review showed that parents typically fail to recognise obesity in their children and adolescents, and a good deal of other evidence suggests that health professionals under-diagnose obesity in children and adolescents when using informal methods based on observation. There is therefore a need for practical, objective, methods that both identify the fattest children and adolescents adequately, and identify those who are at greatest risk of the 'co-morbidities' of obesity. A large body of consistent evidence shows that a high body mass index (BMI) for age and sex identifies the fattest children adequately, with low-moderate false negative rate and a low false positive rate. Furthermore, children and adolescents at high BMI for age are at much greater risk of the co-morbidities of obesity. A recent systematic review found that the use of BMI for age with national reference data and cut-off points (such as the 95th percentile to define obesity) was superior to the Cole-International Obesity Task Force international approach for defining obesity based on BMI for age. The same systematic review also found no evidence that use of waist circumference for age improved the diagnosis of obesity, or the cardio-metabolic co-morbidities of obesity, in children and adolescents. Recent systematic reviews are therefore supportive of current guidelines that recommend percentile-based cut-offs relative to national reference data to (e.g. BMI at or above the 95th or 98th percentile in the UK) to define obesity for clinical applications in children and adolescents.

How useful are systematic reviews of child obesity interventions?

To facilitate the translation of research evidence into practice, policy makers and practitioners require practice-relevant information such as the effectiveness of interventions delivered in specific settings, by various personnel, using various intervention modalities, and descriptions of intervention costs or adverse outcomes. The aim of this study was to review the relevance of information reported in systematic reviews of child obesity interventions in terms of these requirements. A systematic search was conducted for systematic reviews of child obesity interventions published in English between 1990 and 2008. A total of 3150 citations were examined. Of the 44 eligible reviews, 16 examined prevention interventions, 18 examined treatment interventions, and 10 examined both prevention and treatment interventions. Less than 50% of prevention and treatment reviews reported the effect of interventions conducted in specific settings, the effect of interventions conducted by various personnel and the effect of those delivered via various intervention modalities. Similarly, few (4-15%) reviews reported cost or adverse event outcomes. Existing systematic reviews of childhood obesity interventions provide limited practice-relevant information. The potential for benefit from the translation of evidence into practice is therefore limited. Involving end users in systematic review development may improve the relevance of outcomes reported in systematic reviews.

Undernutrition and obesity in indigenous children: epidemiology, prevention, and treatment

Over the past 50 years there has been a shift in nutritional problems amongst Indigenous children in developed countries from under-nutrition and growth faltering to overweight and obesity; the major exception is small numbers of Indigenous children predominately living in remote areas of Northern Australia. Nutritional problems reflect social disadvantage and occur with disproportionately high incidence in all disadvantaged subgroups. There is limited evidence of benefit from any strategies to prevent or treat undernutrition and obesity; there are a limited number of individual studies with generalizable high grade evidence of benefit. Potential solutions require a whole of society approach.

Are overweight adolescents at higher risk of engaging in unhealthy weight-control behaviours?

AIM

To examine correlates of unhealthy weight-control behaviours (UNWCB), and to explore possible associated variables.

METHODS

Sample included 3762, 8th and 10th grade public school Portuguese students who participated in the 2002 Health Behaviour in School-Aged Children (HBSC)/World Health Organization (WHO) survey of adolescent health. Factor analysis was used, and two scales were identified as 'healthy weight-control behaviours' (HWCB) and 'UNWCB' through Kaiser criteria analysis. Frequency scores were developed and used in analysis of variance (ANOVAs) test as dependent variables, according to gender and age. Pearson correlations and post-hoc analysis were performed to identify potential associations.

RESULTS

UNWCB were significantly higher among those who were dieting or not dieting, but considering they should, and were significantly and progressively increasing from those perceiving themselves as thin, to those perceiving themselves as being the right size and those perceiving themselves as fat. Overweight reported more frequently than non-overweight, both HWCB and UNWCB. Finally, there were significant differences concerning alcohol use, with UNWCB increasing progressively from reporting 'drinking rarely or never' to 'drinking every week' and 'everyday'.

CONCLUSION

Because UNWCB are associated with both medical and psychological health risks, routine screening is warranted. Special attention needs to be directed towards youth at greatest risk for disordered eating, including overweight youth.

Development of overweight in children in relation to parental weight and socioeconomic status

The purpose of the study was to test the hypothesis that socioeconomic status (SES) moderates the association between parental weight and changes in BMI from childhood to early adolescence. Participants included 428 twin children from 100 families with obese parents ("obese families") and 114 sociodemographically matched families with normal-weight parents ("lean families") who were assessed in their homes (age = 4.4). Follow-up study was conducted 7 years later (age = 11.2) on 346 children (81%). Complete data were available for 333 children. Family SES was indexed with maternal education. Children's weights and heights were measured to calculate BMI s.d. scores based on 1990 British norms. Overweight was defined as >91st BMI centile. In children with obese parents, BMI s.d. scores increased from 0.51 at age 4 to 1.06 at age 11. In children with lean parents, BMI s.d. scores decreased from 0.11 to 0.05. Prevalence of overweight remained stable from age 4 to 11 in children with lean parents (8% to 9%), but it more than doubled in children with obese parents (17% to 45%). There was a significant interaction between parental weight and family SES (P < 0.01), so that in children with lean parents there was no SES difference in the BMI status from age 4 to 11; however, in children with obese parents, the increase in adiposity was significantly greater in lower SES families. These results suggest that parental leanness confers significant protection against development of overweight in children regardless of family SES, while parental obesity is an adverse prognostic sign, especially in lower SES families.

Physical activity, sedentary behaviour and energy balance in the preschool child: opportunities for early obesity prevention

Prevalence of obesity in preschool children has increased dramatically in recent years. The preschool years (age 3–6 years) have been regarded as critical for the programming of energy balance, via the concept of early ‘adiposity rebound’. Children who undergo early adiposity rebound are at increased risk of later obesity. Recent evidence suggests that associations between timing of adiposity rebound and later obesity may not reflect programming, but might denote that ‘obesogenic’ growth trajectories are often established by the preschool period. Studies of objectively-measured physical activity and sedentary behaviour in preschool children show that levels of physical activity are typically low and sedentary behaviour high. The review of evidence presented here is supportive of the hypothesis that physical activity is protective against obesity in the preschool period, and that sedentary behaviour, particularly television viewing, is obesogenic. Definitive evidence on dose–response relationships between physical activity, sedentary behaviour and obesity remain unclear. Dose–response evidence could be obtained fairly readily by intervention and longitudinal observational studies that use accelerometry in preschool children. The generalisability of much of the evidence base is limited and there is a need for research on the influence of physical activity and sedentary behaviour in the preschool years in the aetiology of obesity in the developing world.

Head Start teachers' perceptions of children's eating behavior and weight status in the context of food scarcity

OBJECTIVE

To describe Head Start teachers' perceptions of mealtime, feeding, and overweight risk in Head Start students.

DESIGN

Qualitative focus group study.

SETTING

Five Head Starts in a greater metropolitan area in the Northeast.

PARTICIPANTS

Thirty-five teachers in 5 focus groups.

INTERVENTION

Two experienced focus group facilitators elicited comments from each group.

MAIN OUTCOME MEASURE

Identification of themes for future nutrition education programming.

ANALYSIS

Participant comments were transcribed and common themes identified by 7 readers.

RESULTS

Teachers felt (1) empowered to shape the content of children's diets; (2) that meals served at Head Start were chaotic; (3) uncertain how to address children's voracious appetites, since children often were from homes with limited food resources; (4) skeptical about the definition of overweight; (5) that children's eating behaviors and their weight status were not connected; and (6) uncomfortable addressing overweight with students' families.

CONCLUSIONS AND IMPLICATIONS

Teachers' skepticism about overweight, uncertainty around managing the seemingly voracious eating behavior of children perceived as hungry as a result of inadequate food at home, and discomfort in addressing overweight with families may all represent nutrition education opportunities. Tailoring prevention programs such that they evoke support and agreement from these teachers as well as harnessing strengths, such as teachers' confidence in shaping children's eating behaviors, will be important.

Randomized, controlled trial of a best-practice individualized behavioral program for treatment of childhood overweight: Scottish Childhood Overweight Treatment Trial (SCOTT)

OBJECTIVE

The objective of this study was to determine whether a generalizable best-practice individualized behavioral intervention reduced BMI z score relative to standard dietetic care among overweight children.

METHODS

The design consisted of an assessor-blinded, randomized, controlled trial involving 134 overweight children (59 boys, 75 girls; BMI > or = 98th centile relative to United Kingdom 1990 reference data for children aged 5-11 years) who were randomly assigned to a best-practice behavioral program (intervention) or standard care (control). The intervention used family-centered counseling and behavioral strategies to modify diet, physical activity, and sedentary behavior. BMI z score, weight, objectively measured physical activity and sedentary behavior, fat distribution, quality of life, and height z score were recorded at baseline and at 6 and 12 months.

RESULTS

The intervention had no significant effect relative to standard care on BMI z score from baseline to 6 months and 12 months. BMI z score decreased significantly in both groups from baseline to 6 and 12 months. For those who complied with treatment, there was a significantly smaller weight increase in those in the intervention group compared with control subjects from baseline to 6 months. There were significant between-group differences in favor of the intervention for changes in total physical activity, percentage of time spent in sedentary behavior, and light-intensity physical activity.

CONCLUSIONS

A generalizable, best-practice individualized behavioral intervention had modest benefits on objectively measured physical activity and sedentary behavior but no significant effect on BMI z score compared with standard care among overweight children. The modest magnitude of the benefits observed perhaps argues for a longer-term and more intense intervention, although such treatments may not be realistic for many health care systems.

Gendered dimensions of obesity in childhood and adolescence

Background

The literature on childhood and adolescent obesity is vast. In addition to producing a general overview, this paper aims to highlight gender differences or similarities, an area which has tended not to be the principal focus of this literature.

Methods

Databases were searched using the terms 'obesity' and 'child', 'adolescent', 'teenager', 'youth', 'young people', 'sex', 'gender', 'masculine', 'feminine', 'male', 'female', 'boy' and 'girl' (or variations on these terms). In order to limit the potential literature, the main focus is on other reviews, both general and relating to specific aspects of obesity.

Results

The findings of genetic studies are similar for males and females, and differences in obesity rates as defined by body mass index are generally small and inconsistent. However, differences between males and females due to biology are evident in the patterning of body fat, the fat levels at which health risks become apparent, levels of resting energy expenditure and energy requirements, ability to engage in certain physical activities and the consequences of obesity for the female reproductive system. Differences due to society or culture include food choices and dietary concerns, overall physical activity levels, body satisfaction and the long-term psychosocial consequences of childhood and adolescent obesity.

Conclusion

This review suggests differences between males and females in exposure and vulnerability to obesogenic environments, the consequences of child and adolescent obesity, and responses to interventions for the condition. A clearer focus on gender differences is required among both researchers and policy makers within this field.

Changing incidence of slipped capital femoral epiphysis

Obesity is thought to be an aetiological factor for slipped capital femoral epiphysis (SCFE). We analysed changes in the incidence of SCFE in Scotland over the last two decades. During this period rates of childhood obesity have risen substantially and evidence for a relationship between these changes and the incidence of SCFE was sought.

We found that the incidence of SCFE increased from 3.78 per 100 000 children in 1981 to 9.66 per 100 000 in 2000 (R2 = 0.715): a two and a half times increase over two decades. It was seen at a younger age, with a fall in the mean age at diagnosis from 13.4 to 12.6 years for boys (p = 0.007) and 12.2 to 11.6 for girls (p = 0.047). More children under eight years old were seen with SCFE in Scotland in the decade to 2000 than in the previous decade (p = 0.002, R2 = 0.346).

A close correlation was observed between rising childhood obesity over the last 20 years in Scotland and an increasing incidence of SCFE.

Obesity in Swedish schoolchildren is increasing in both prevalence and severity

PURPOSE

To monitor and describe, on a national level, the development of body mass index (BMI), overweight, and obesity of schoolchildren in Sweden aged 7-18 years over a period of 8 years.

METHODS

Longitudinal and cross-sectional studies of two nationally representative cohorts. A representative sample of 3,749 individuals from a birth cohort of 109,663 individuals born in 1973, and another representative sample of 3,158 individuals from a birth cohort of 94,064 individuals born in 1981; 4.5% and 1.6% of those born in 1973 and 1981, respectively, were missing from the sample. Data regarding height and weight from school health records.

RESULTS

From age 7-18 year, a strong positive secular change in BMI is found at all ages, and the rate of overweight and obesity is increasing for both boys and girls. Furthermore, obesity is growing more severe.

CONCLUSIONS

Nationally representative longitudinal BMI data for two cohorts, in which nonresponse bias is minimized, permitted monitoring and revealed a nationwide strongly positive secular change in BMI in Sweden, over a period of 8 years for individuals aged 7-18 years.

Methodological limitations in measuring childhood and adolescent obesity and overweight in epidemiological studies: does overweight fare better than obesity?

Objectives

International definitions of childhood obesity based on body mass index (BMI) are intended to be used for international comparisons of obesity prevalence. In general, they are not appropriate to be used in clinical practice. The objective of this study is to compare international-ecological vs. national-clinical reference data of obesity in Spain, as well as to describe trends.

Design

Cross-sectional study from a representative national random sample of Spanish children and youth conducted between 1998 and 2000. Prevalence estimates of obesity in a national random sample of Spanish children and youth are presented in this paper, defined by age- and sex-specific BMI national reference standards for the 85th percentile (overweight) and 95th percentile (obesity), as well as by Cole et al. criteria. The study protocol included personal data, data on education and socio-economic status for the family and anthropometric measurements.

Setting

Population-based study set in Spain.

Subjects

A random sample of 3534 individuals, aged 2–24 years.

Results

Prevalence of obesity using national reference data was higher (15.3%) than using international data (5.8%), but overweight rates were similar. Agreement observed for both definitions was low for obesity but higher for overweight. Obesity trends among children and adolescents in Spain show increasing patterns in boys but not in girls.

Conclusions

Results indicate the need to standardise the definitions of obesity and overweight in childhood and recommend the use of overweight due to the greater degree of agreement observed among the different methods used. The IOTF reference method underestimates obesity rates in Spanish schoolchildren.