Visceral adipose tissue and cardiovascular risk factors in obese children

Epicardial Fat Volume Assessed by MRI in Adolescents: Associations with Obesity and Cardiovascular Risk Factors

Background: In adults, epicardial adipose tissue (EAT) is associated with metabolic syndrome (MS) and coronary artery disease. EAT thickness is increased in obese youth, but total EAT volume and its correlation with cardiovascular risk factors have not been studied. Objectives: To determine EAT volume in adolescents and its association with obesity and cardiovascular risk factors. Methods: We performed a cross-sectional study including 48 pubertal adolescents (24 obese and 24 lean subjects, aged 13.6 ± 1.5 yr). EAT volume as well as visceral and subcutaneous abdominal adipose tissue volumes were obtained by magnetic resonance imaging. Anthropometrical parameters; blood pressure (BP); fasting serum triglycerides; total and low- and high-density lipoprotein (HDL-C) cholesterol; glucose; and insulin levels were measured. Results: Obese adolescents had higher EAT volume compared to lean controls (49.6 ± 18.0 vs. 17.6 ± 6.7 cm3, p < 0.0005). They also had significantly increased visceral abdominal fat volumes, systolic BP, serum triglycerides, and insulin levels, and decreased HDL-C concentration. EAT volume was significantly associated with anthropometrical indices and cardiovascular risk factors: waist circumference, systolic BP, triglycerides, HDL-C levels, and insulin resistance indices. Metabolic syndrome was present in 25% of obese adolescents. EAT volume was significantly higher in obese adolescents with MS compared to those without MS (63.5 ± 21.4 vs. 44.9 ± 14.6 cm3, p = 0.026). Conclusions: EAT volume, which is known to contribute to atherogenesis in adults, is increased in obese adolescents, and is associated with abdominal visceral fat, cardiovascular risk factors, and MS. Excessive EAT early in life may contribute to the development of premature cardiometabolic disease.

Performance of triponderal mass index, body mass index z scores, and body mass index performance in the diagnosis of obesity in children and adolescents

OBJECTIVES

Childhood obesity is a global health problem that affects millions of children and causes obesity-related adverse health outcomes in both childhood and adulthood. Although body mass index (BMI) z scores and percentiles are used in the diagnosis of obesity in children, it has been emphasized in recent years that the triponderal mass index (TMI) may be more accurate for this purpose. We aimed to compare TMI with BMI in the diagnosis of obesity in Turkish children and adolescents.

METHODS

The records of 3540 children who applied to Gülhane Training and Research Hospital were retrospectively scanned and the data of 1161 children were included in the study. The body fat percentage (BF%) was calculated by a formula, and children with body fat in the ≥95th percentile were classified as obese. Receiver study characteristics analysis was performed to compare the effectiveness of TMI and BMI in the diagnosis of obesity.

RESULTS

TMI correlated more with BF% (r = 0.863) than fat mass (r = 0.664); BMI correlated more with fat mass (r = 0.957) than BF% (r = 0.714) (P < 0.001). TMI had the highest area under the curve (AUC) in boys at diagnosis of obesity (6-11 y = 0.981; 12-15 y = 0.994). Girls ages 6 to 11 y had the same AUC for all 3 indexes (AUC = 0.977), whereas girls ages 12 to 15 y had the highest AUC for TMI (AUC = 0.967). However, the AUC values between all indices were very close.

CONCLUSIONS

TMI can be used to diagnose obesity in Turkish children and adolescents in both boys and girls similarly and with good performance. The correlation with BF% and stability of TMI makes this index more advantageous. However, it should be noted that the performance of each of the 3 indices is very close to that of the others, and adjustments should be made according to age and sex.

Identifying metabolic syndrome in migrant Asian Indian adults with anthropometric and visceral fat action points

BACKGROUND

Metabolic syndrome (MetS) is a clustering of metabolic risk factors, including large waist circumference (WC). Other anthropometric parameters and visceral fat mass (VFM) predicted from these may improve MetS detection. Our aim was to assess the ability of such parameters to predict this clustering in a cross-sectional, diagnostic study.

METHOD

Participants were 82 males and 86 females, aged 20-74 years, of Asian Indian ethnicity. VFM was estimated by dual-energy X-ray absorptiometry (DXA) through identification of abdominal subcutaneous fat layer boundaries. Non-anthropometric metabolic risk factors (triglycerides, HDL cholesterol, blood pressure and glucose) were defined using MetS criteria. We estimated the ability of anthropometry and VFM to detect ≥ 2 of these factors by receiver operating characteristic (ROC) and precision-recall curves.

RESULTS

Two or more non-anthropometric metabolic risk factors were present in 45 (55%) males and 29 (34%) females. The area under the ROC curve (AUC) to predict ≥ 2 of these factors using WC was 0.67 (95% confidence interval: 0.55-0.79) in males and 0.65 (0.53-0.77) in females. Optimal WC cut-points were 92 cm for males (63% accuracy) and 79 cm for females (53% accuracy). VFM, DXA-measured sagittal diameter and suprailiac skinfold thickness yielded higher AUC point estimates (by up to 0.06), especially in females where these measures improved accuracy to 69%, 69% and 65%, respectively. Pairwise combinations that included WC further improved accuracy.

CONCLUSION

Our findings indicate that cut-points for readily obtained measures other than WC, or in combination with WC, may provide improved detection of MetS risk factor clusters.

Associations of DXA-measured abdominal adiposity with cardio-metabolic risk and related markers in early adolescence in Project Viva

BACKGROUND

Increased visceral adipose tissue (VAT) precedes development of insulin resistance and dyslipidemia in adults. The associations of abdominal adiposity derived from dual-energy X-ray absorptiometry (DXA), including VAT, subcutaneous abdominal adipose tissue (SAAT) and total abdominal adipose tissue (TAAT) with cardio-metabolic risk in adolescents are understudied.

OBJECTIVES

We examined the cross-sectional associations of DXA-measured abdominal adiposity with cardio-metabolic risk and related markers in early adolescence (mean [SD] age 13.0 [0.7] years).

METHODS

We collected data from 740 adolescents (374 girls and 366 boys) in Project Viva, a U.S. pre-birth cohort. We used DXA estimates of VAT, SAAT and TAAT area. We conducted overall and sex-stratified linear regression models, adjusting for age, sex (in overall models), race/ethnicity, puberty score and body mass index (BMI) z-score.

RESULTS

Mean BMI z-score was 0.59 (1.28). After adjustment, greater VAT (per 1 SD score) was associated with higher metabolic risk z-score (β 0.14 units; 95% CI 0.08, 0.20), higher log high-sensitivity C-reactive protein (β 0.51 mg/L; 0.36, 0.66) and log leptin (β 0.36 ng/mL; 0.27, 0.44), and lower log adiponectin (β -0.08 ug/mL; -0.13, -0.02). SAAT and TAAT showed similar associations as VAT with comparable or greater effect sizes.

CONCLUSION

In early adolescence, DXA-measured VAT, SAAT and TAAT are associated with cardio-metabolic risk and related markers, independent of current BMI. Among two adolescents with the same BMI, there is an associated higher cardio-metabolic risk in the adolescent with greater DXA-measured abdominal adiposity.

Early start of growth hormone is associated with positive effects on auxology and metabolism in Prader-Willi-syndrome

BACKGROUND

Prader-Willi-Syndrome (PWS) is characterized by hypothalamic-pituitary dysfunction. Recent research suggests starting growth hormone-treatment (GHT) as soon as possible. The aim of this study is to analyze possible differences in auxological parameters, carbohydrate and lipid metabolism between two groups of children with PWS that started GHT either during or after their first year of life.

STUDY DESIGN

Retrospective longitudinal study of 62 children (31 males) with genetically confirmed PWS. Upon diagnosis all children were offered GHT, some started immediately, others commenced later. Cohort A (n = 21; 11 males) started GHT at 0.3-0.99 yrs. (mean 0.72 yrs) and Cohort B (n = 41; 20 males) commenced GHT at 1.02-2.54 yrs. (mean 1.42 yrs) of age. Fasting morning blood samples and auxological parameters were obtained before the start of therapy and semi-annually thereafter. Differences between the two cohorts were estimated with a linear mixed-effect model.

RESULTS

Mean length/height-SDS_PWS differed significantly between the groups [1 yr: A: 0.37 (±0.83) vs B: 0.05 (±0.56); 5 yrs.: A: 0.81 (±0.67) vs B: 0.54 (±0.64); p = 0.012]. No significant differences were found in BMI, lean body mass or body fat. Low-density cholesterol was significantly lower in A than in B [LDL: 1 yr: A: 79 (±20) mg/dl vs B: 90 (±19) mg/dl; 5 yrs.: A: 91(±18) mg/dl vs 104 (±26) mg/dl; p = 0.024]. We found significant differences in the glucose homeostasis between the groups [fasting insulin: p = 0.012; HOMA-IR: p = 0.006; HbA1c: p < 0.001; blood glucose: p = 0.022].

CONCLUSIONS

An early start of GHT during the first year of life seems to have a favorable effect on height-SDS and metabolic parameters.

Growing up strong: The importance of physical, mental, and emotional strength during childhood and adolescence with focus on dietary factors

Childhood and adolescence are critical time periods for growth and development. Given the current physical and psychological health concerns affecting United States youth, an emerging area of interest exists supporting the importance of physical and psychological aspects of strength for health, resilience, and well-being through these life stages. This synopsis highlights the key concepts that were presented within the 2018 Strength Summit conference, entitled The Role of Strength in Optimal Health and Well-being. During the conference, strength was broadly defined as the ability to successfully respond to a challenge. Although much of the current research focuses on strength from a muscle function and performance perspective, mental and emotional strength are also important components of overall health and well-being, especially in children and adolescents. This paper provides a brief overview of the clinical and/or research-based strength outcomes, summarizes the relationship between strength and health, and discusses evidence-based dietary factors that promote strength in children and adolescents. Novelty Building physical, mental, and emotional strength during childhood and adolescence lays the foundation for health and well-being. Emerging evidence indicate positive associations between diet quality and strength in children and adolescents. Promising areas include the promotion of family-based meals, with focus on breakfast, for improved strength in United States youth.

Four-second dynamic exercise testing (T4S) for the assessment of cardiac vagal modulation in obese adolescents

BACKGROUND

Reduced vagal activity is often present in obese adolescents. Simple and practical strategies for the assessment of isolate parasympathetic outflow in this population are therefore useful.

OBJECTIVES

To compare the methods derived from heart rate variability (HRV) analysis at rest and 4 s exercise testing (T4S) for the assessment of cardiac parasympathetic modulation in adolescents classified as obese (OB) or with normal weight (NW). Additionally, associations between total and trunk fat versus autonomic modulation determined by the two methods were calculated.

APPROACH

A cross-sectional study was conducted with 50 adolescents (26 OB and 24 NW, 14.7  ±  1.5 years), comparing autonomic indices provided by HRV and T4S. Body fractioning was determined employing dual-energy x-ray absorptiometry (DXA).

MAIN RESULTS

The cardiac vagal index (CVI) obtained from T4S and standard time- and frequency-domain HRV measures were lower in OB versus NW (P  ⩽  0.05). Correlations between CVI and HRV indices of cardiac vagal modulation were as follows: CVI versus RMSSD (r  =  0.44; P  =  0.003); CVI versus pNN50 (r  =  0.32; P  =  0.04); CVI versus HF (r  =  0.35; P  =  0.02). Associations between body fat, android/gynoid ratio, and percent trunk fat versus CVI were of similar magnitude and direction than versus HRV indices.

SIGNIFICANCE

The T4S proved to be adequate to detect cardiac parasympathetic impairment in obese adolescents. Moreover, vagal modulation assessed by HRV and T4S inversely correlated with visceral adipose tissue. These findings along with the simplicity and safety of the T4S should encourage its use in the assessment of cardiac parasympathetic modulation in obese pediatric populations.

Metabolic Risk Factors Associated with Visceral and Subcutaneous Adipose Tissue in a Sex-Specific Manner in Seven-Year-Olds

OBJECTIVE

This study aimed to investigate how visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) volumes were associated with metabolic risk factors in 7-year-old children.

METHODS

A total of 81 children (52% girls) from a Swedish birth cohort were studied. At 6 years of age, anthropometric data, fasting insulin, glucose, cholesterol, and blood pressure were collected on 53 children with normal weight and 28 children with overweight or obesity, and insulin resistance was estimated. At 7 years of age, magnetic resonance imaging quantified VAT and SAT. Sex and regression analyses were conducted.

RESULTS

SAT was more strongly associated with metabolic risk factors than VAT. The associations between VAT and metabolic risk factors were stronger in girls (P < 0.05). When VAT was adjusted for birth weight and maternal BMI and education, it accounted for 51% of insulin variance (β = 11.72; P = 0.001) but only in girls. The key finding of this study was that adjusted SAT accounted for 63% of the fasting insulin variance in girls (β = 2.76; P < 0.001). Waist circumference was the best anthropometric marker for insulin resistance.

CONCLUSIONS

Insulin resistance was associated with abdominal adipose tissue and its associated metabolic risk factors in children as young as 7 years old.

Relations between mode of birth delivery and timing of developmental milestones and adiposity in preadolescence: A retrospective study

BACKGROUND

Cesarean delivery (CS) is an increasingly common mode of delivery comprising over 30% of all deliveries in the U.S. The long-term impact of this delivery mode on child development remains unclear.

AIMS

We investigated the relationship between mode of delivery (vaginal vs. CS) and timing of developmental milestones and adiposity in preadolescence, as well as additional milestones beyond motor/language development including toilet training, dressing, and feeding self.

STUDY DESIGN

This study utilized a retrospective survey given to a parent/guardian and dual energy x-ray absorptiometry in preadolescence, respectively. A composite z-score was calculated based on nine questions pertaining to developmental milestones i.e., parent-reported age for supporting head by self, rolling over, sitting up, standing, walking, talking, toilet-training, dressing, and feeding self.

SUBJECTS

7-10-year-old (N = 104) children in East-Central Illinois.

OUTCOME MEASURES

Composite z-score for timing of attainment of developmental milestones, mode of delivery, and preadolescent adiposity.

RESULTS

Vaginally-born children had a lower composite z-score, signifying earlier attainment of developmental milestones, relative to both emergency and planned CS-born children. Further, elective CS-born children had greater adiposity in preadolescence, relative to vaginal and emergency cesarean-section born children.

CONCLUSIONS

These findings suggest relationships between delivery mode, developmental milestones, and obesity in preadolescence. Additionally, they provide novel insights into the differential impact of elective versus emergency CS.

Ultrasound as a method to evaluate the distribution of abdominal fat in obese prepubertal children and the relationship between abdominal fat and metabolic alterations

Abstract

Effects of exercise intervention on visceral fat in obese children and adolescents

INTRODUCTION

This meta-analysis study was aimed to assess the effects of exercise intervention on visceral fat in obese children and adolescents.

EVIDENCE ACQUISITION

Electronic database searches were performed in Academic Search Complete, CINAHL, Healthsource, MEDLINE, and SportDiscus, and from the earliest record to November 2017. Keywords included "exercise or training," "visceral fat," and "child or adolescent or youth." The inclusion criteria for eligible studies were as follows: 1) subjects were obese at baseline; 2) aged 6-19 years; 3) visceral fat was reported at baseline and after an intervention; and 4) studies were published in peer-reviewed journals written in English.

EVIDENCE SYNTHESIS

A total of 207 studies were observed at the initial search and 73 effect sizes (ESs) were derived from the 34 selected studies. The overall exercise intervention effect was large (Cohen's d [ES]=-1.003, 95% CI=-1.114, -0.892). Moderator analyses results showed that gender (Qb=8.23, df=2, P=0.016), exercise type (Qb=10.68, df=2, P=0.005), and intervention length (Qb=24.71, df=2, P<0.001) influenced the overall ES.

CONCLUSIONS

The group of both boys and girls (ES=-0.95) who participated combined exercise program (Aerobic + Resistance training; ES=-1.17) for 12 months (ES=-1.24) appeared to be the most effective exercise strategy for reducing visceral fat in obese youth.

Intrauterine growth restriction combined with a maternal high-fat diet increased adiposity and serum corticosterone levels in adult rat offspring

Intrauterine growth restriction (IUGR) and fetal exposure to a maternal high-fat diet (HFD) independently increase the risk of developing obesity in adulthood. Excess glucocorticoids increase obesity. We hypothesized that surgically induced IUGR combined with an HFD would increase adiposity and glucocorticoids more than in non-IUGR offspring combined with the same HFD, findings that would persist despite weaning to a regular diet. Non-IUGR (N) and IUGR (I) rat offspring from dams fed either regular rat chow (R) or an HFD (H) were weaned to either a regular rat chow or an HFD. For non-IUGR and IUGR rats, this study design resulted in three diet groups: offspring from dams fed a regular diet and weaned to a regular diet (NRR and IRR), offspring rats from dams fed an HFD and weaned to a regular diet (NHR and IHR) and offspring from dams fed an HFD and weaned to an HFD (NHH and IHH). Magnetic resonance imaging or fasting visceral and subcutaneous adipose tissue collection occurred at postnatal day 60. IHH male rats had greater adiposity than NHH males, findings that were only partly normalized by weaning to a regular chow. IHH male rats had a 10-fold increase in serum corticosterone levels. IHH female rats had increased adiposity and serum triglycerides. We conclude that IUGR combined with an HFD throughout life increased adiposity, glucocorticoids and triglycerides in a sex-specific manner. Our data suggest that one mechanism through which the perinatal environment programs increased adiposity in IHH male rats may be via increased systemic glucocorticoids.

Association between individual fat depots and cardio-metabolic traits in normal- and overweight children, adolescents and adults

OBJECTIVES

To determine age-related associations between fat mass (FM), regional fat depots and cardiometabolic traits in normal- and overweight children, adolescents and adults.

METHODS

Detailed body composition (regional subcutaneous and visceral adipose tissue; SAT, VAT) by whole-body magnetic resonance imaging (MRI), FM and fat-free mass by air-displacement plethysmography, systolic and diastolic blood pressure (SBP, DBP), triglycerides (TG), high-density lipoprotein cholesterol (HDL), plasma glucose and plasma insulin were measured in 433 subjects (BMI: 23.6 (21.0-27.7); 151 children and adolescents, aged 6-18 years, 150 young adults, aged 18-30 years and 132 adults, aged 30-60 years). Data were derived from pooled data of the 'Reference Center for Body Composition' in Kiel, Germany. Insulin resistance was determined by the homeostatic model assessment of insulin resistance (HOMA-IR). Partial correlations and multivariate linear regression analyses were used to evaluate the associations between body composition and cardiometabolic traits. A descriptive approach was used to demonstrate age-dependent differences in associations between body fat depots and insulin resistance, independent of BMI.

RESULTS

FM, SAT, and VAT increased from childhood to adulthood with low VAT in children and adolescents. When compared to children, TG was higher in adults. HDL and DBP did not differ between age groups. Insulin resistance was highest in male adolescents and female young adults. Associations between body fat depots and cardiometabolic traits were seen after puberty with no associations in pre- and intrapubertal children. When compared to FM, SAT and VAT had the strongest association with insulin resistance in adults. This association was independent of BMI.

CONCLUSIONS

Associations between individual body fat depots and most cardiometabolic traits became evident after puberty only. The strongest associations were observed between insulin resistance and abdominal fat in adults. The impact of VAT was independent of BMI.

Intra-abdominal and subcutaneous abdominal fat as predictors of cardiometabolic risk in a sample of Mexican children

BACKGROUND/OBJECTIVE

Few studies in Latin American paediatric populations have differentiated fat deposits in specific areas, such as intra-abdominal fat (IAF) and subcutaneous abdominal fat (SAF). Research in diverse populations is needed, as patterns of fat accumulation vary by ethnicity. The aim of this study was to determine whether IAF and/or SAF are related to cardiometabolic risk factors, independent of total body fat (TBF), in a group of Mexican schoolchildren.

SUBJECTS/METHODS

A cross-sectional study was conducted in Mexico City with 94 children aged between 5 and 11 years. IAF and SAF were assessed by magnetic resonance using two different estimation methods: (a) at the midpoint of lumbar vertebras 4 and 5 (L4-L5) and (b) the sum of the areas of four slices (L1-L2, L2-L3, L3-L4 and L4-L5, which will be referred to as 'total' IAF and SAF). TBF was measured by dual-energy X-ray absorptiometry. The following cardiometabolic risk factors were assessed: total cholesterol, low-density lipoprotein-cholesterol, triglycerides, glucose, insulin, high-density lipoprotein-cholesterol, blood pressure, insulin resistance, number of risk factors and metabolic syndrome score.

RESULTS

After adjusting for sex, age and TBF, total SAF was related to the number of cardiometabolic risk factors and metabolic syndrome score. Although IAF at L4-L5 was also related to the number of cardiometabolic risk factors, there was evidence of collinearity with TBF.

CONCLUSIONS

In this sample of Mexican schoolchildren, TBF and SAF, but not IAF, were associated with higher cardiometabolic risk.

Neck Circumference to Assess Obesity in Preschool Children

OBJECTIVE

Limited information is available about the use of neck circumference (NC) to assess obesity in preschool children. This study aims to provide NC percentiles and determine the cut-off levels of NC as a measure to assess obesity in preschool children.

METHODS

The data were obtained from the Anthropometry of Turkish Children aged 0-6 years (ATCA-06) study database. A total of 21 family health centers were chosen and children aged 2-6 years old from all socioeconomic levels were randomly selected from the lists of district midwives; 1766 children (874 male and 892 female; 88.3% of sample size) were included in the study. The smoothed centile curves of NC were constructed by the LMS method. Receiver operating characteristic (ROC) analysis was performed to calculate cut-off points for NC using body mass index ≥95^th percentile.

RESULTS

Mean NC was greater in males than females. Cut-off values for obesity were found to be statistically significant in both genders other than 3 years old boys. The NC percentiles of Turkish preschool children were slightly greater than those of other European preschool children in both genders. This difference disappeared around the adiposity rebound period. The 97th percentile values for Turkish preschool children continue to be greater in both genders.

CONCLUSION

NC may be useful to define obesity in preschool children. Since ethnic and various other factors may have a role in incidence of obesity, local reference data are important in assessment of obesity.

Neck Circumference-Height Ratio as a Predictor of Sleep Related Breathing Disorder in Children and Adults

STUDY OBJECTIVES

While neck circumference (NC) is a useful predictor of obstructive sleep apnea (OSA) in adults, childhood OSA is difficult to predict clinically. We utilized the neck circumference-height ratio (NHR) to normalize NC in growing children. Our study aimed to determine if (1) NC is a reproducible clinical measurement; (2) NHR predicts OSA in children; (3) this metric translates to adults.

METHODS

For this retrospective study, paired NC measurements (from clinic and sleep laboratory) in 100 consecutive adult subjects were used to confirm inter-observer reproducibility. Polysomnographic (PSG) and anthropometric data from children aged 5-18 years presenting consecutively between July 2007 and February 2012 was obtained. Children with genetic syndromes, severe neurological disorders, craniofacial abnormalities, tracheostomy, past adenotonsillectomy, in-hospital PSG or sleep efficiency < 80% were excluded. Data were analyzed using χ(2) test and logistic and linear regression models. These analyses were also applied to 99 adult patients with similar exclusion criteria.

RESULTS

Adult NC measurement had inter-observer correlation of 0.85 (N = 100). Among children, after correcting for BMI-Z scores, NHR conferred additional predictive value, in both logistic regression and linear models, for both apnea-hypopnea index (AHI) > 2 and > 5 (N = 507). In children, for NHR > 0.25, the odds ratio of AHI > 2 was 3.47. In adults, for NHR > 0.25, the odds ratio of AHI > 5 was 18.

CONCLUSIONS

NHR can be included as a simple screening tool for OSA in children and adults, which along with other predictors, may improve the ability of clinicians to triage children and adults at risk for OSA for further evaluation with PSG.

Increased Ratio of Trunk-to-Appendicular Fat and Decreased Adiponectin: A Population-Based Study of School Children in Hamamatsu, Japan

Very few epidemiological studies have examined the relative impact of visceral fat and subcutaneous fat on serum adiponectin levels. Trunk-to-extremity fat ratio is reportedly a better surrogate for visceral fat than for subcutaneous fat. In the present study, we investigated the association between adiponectin and trunk-to-appendicular fat ratio (TAR) in a school population. The source population was all fifth graders (799 pupils) enrolled in the 2 elementary schools in Hamamatsu, Japan. Of the source population, we analyzed cross-sectional data from 609 children (mean age: 11.2 yr). TAR was evaluated by dual-energy X-ray absorptiometry and calculated as trunk fat mass divided by appendicular (arms and legs) fat mass. After stratification by tertiles of total body fat, multiple regression analysis was used to examine the relationships between adiponectin and TAR adjusted for potential confounding factors. In the highest tertile of total body fat, increasing TARs were significantly (p < 0.05) associated with decreasing serum adiponectin levels after stratification by total body fat (β = -0.32 in boys; β = -0.31 in girls). In the second tertile of total body fat, TAR in girls also showed significant inverse relationships with serum adiponectin levels (β = -0.27). Data from this population-based study demonstrated that an increased proportion of trunk fat is associated with decreased adiponectin in relatively overweight children, and also demonstrated that girls with a normal volume of body fat that follows a more centralized distribution show decreased adiponectin.

Exercise Intervention Improves the Metabolic Profile and Body Composition of Southwestern American Indian Adolescents

Introduction/Purpose

The Southwestern American Indian population carries a high prevalence of metabolic syndrome and obesity, placing this group at higher risk than the general population for developing early type 2 diabetes and cardiovascular disease, likely impacting overall lifespan. This study aims to evaluate the impact of early lifestyle interventions which promote healthy eating and regular exercise on risk factors contributing to the development of the metabolic syndrome among the adolescent Zuni Pueblo population.

Materials and Methods

We describe a prospective, single site, community-based cohort study performed among sixty-five adolescent Zuni Indians aged 13.9 ± 1.7 years who were recruited between March 2011 and January 2014. The study intervention consisted of a targeted, tri-weekly exercise regimen with nutritional counselling, and the primary study outcomes included changes from baseline in metabolic profile (fasting lipids, A1c), vital signs (blood pressure, resting heart rate) and anthropometric characteristics of the study group.

Results

41 participants have anthropometric data measured at baseline and after completion, biochemical data are available from 30 participants, and body composition data from 26 patients. Using the paired Student’s t-test with Bonferroni correction, significant improvements were shown in pediatric BMI percentile, fasting lipid profile, A1C, total body fat, and fat free mass after six months of exercise and nutritional intervention.

Conclusions

A simple, standardized fitness program among Southwest American Indian adolescents was effective at reducing fasting lipids and adiposity, as well as improving glycemic indices over the course of six months.

Dexa Body Composition Assessment in 10-11 Year Healthy Children

INTRODUCTION

Obesity is a growing health problem associated with metabolic derangements and cardiovascular disease. Accumulating evidence links the accumulation of visceral adipose tissue (VAT) to these obesity related health risks in adults. Childhood obesity is associated with a lifetime risk of cardiovascular disease and poses a serious challenge to future health care. In children, there is much less data on the prevalence and gender differences of visceral obesity than in adults. This study aims to provide reference values for VAT in children 10-11 years of age.

METHODS

In a cross-sectional study performed in the north western part of theNetherlands, healthy children of 10-11 years of age, were recruited from primary schools. Anthropometric data consisting of height, weight, waist circumference (WC) and BMI were measured. Body composition was measured using DXA, providing measures for bone mineral content, total fat mass (TFM), lean body mass (LBM) and VAT.

RESULTS

217 children were eligible for this study. Girls appeared to have a greater TFM (31.4% vs 27.5% of total body weight (TBW); P < .01) but lower VAT (0.3% vs 0.5% of TBW;P < .01) than boys, whereas boys had higher LBM (65.4% vs 69.3% TBW;P < .01). Median VAT area (cm2) was 41.1 for boys and 22.4 for girls (P < .01). Moderate to strong correlations were found for WC and BMI with VAT (boys: r = .664 and r = .630; Girls r = .699 and r = .546 respectively all P < .001).

DISCUSSION

This study shows gender specific differences in VAT percentiles in healthy non-obese 10-11 year old children as measured by DXA that may serve as reference values in children. Independent of BMI and WC, girls tend to have more TFM but less VAT and LBM than boys.

Specific BIVA recognizes variation of body mass and body composition: Two related but different facets of nutritional status

OBJECTIVE

The aim of this study was to demonstrate the different information provided by body mass index (BMI) in combination with specific bioelectrical impedance vector analysis (specific BIVA) in the measure of relative body fat.

METHODS

Anthropometric and bioelectrical values and dual-energy x-ray absorpitometry measurements from a sample of 1590 US adults of both sexes were retrieved from the National Health and Nutrition Examination Survey 2003-2004. The sample distribution of the BMI of each sex was divided into deciles. Quartiles were calculated for percent fat mass (FM%) after stratifying by BMI deciles. Body composition and bioelectrical characteristics of groups below the first and above the third quartile were compared using analysis of variance and the Hotelling's T-square test.

RESULTS

BMI and specific BIVA showed a different accuracy in detecting body composition variations: BMI showed similar values in groups represented by different FM percentages, whereas the bioelectrical differences were statistically significant. The mean impedance vectors corresponding to cases below the first FM% quartiles were shorter and located on the left side of the ellipses (the region of higher fat-free mass), whereas those above the third FM% quartiles were on the right and toward the upper pole (the region of higher FM%).

CONCLUSIONS

Specific BIVA is a technique for the evaluation of body composition which can add relevant information regarding BMI.

Passive Smoke Exposure and Its Effects on Cognition, Sleep, and Health Outcomes in Overweight and Obese Children

BACKGROUND

Passive smoke exposure (PSE) may be a risk factor for childhood overweight and obesity and is associated with worse neurocognitive development, cognition, and sleep in children. The purpose of the study is to examine the effects of PSE on adiposity, cognition, and sleep in overweight and obese children using an objective measure of PSE.

METHODS

Overweight or obese children (n = 222) aged 7-11 (9.4 ± 1.1 years; 58% black; 58% female; 85% obese) were recruited from schools near Augusta, Georgia, over the course of the school year from 2003-2006 for a clinical trial, with data analyzed in 2009-2010. Passive smoke exposure was measured with plasma cotinine. Health, cognitive, and sleep measures and parent report of smoke exposure were obtained.

RESULTS

Overweight and obese children with PSE had greater overall and central adiposity than nonexposed overweight and obese children (p < 0.03). However, PSE was unrelated to prediabetes, insulin resistance, or visceral fat. PSE was linked to poorer cognitive scores (p < 0.04) independent of adiposity, but was not related to sleep-disordered breathing.

CONCLUSIONS

PSE is associated with fatness and poorer cognition in children. Tailored interventions that target multiple health risk factors including nutrition, physical activity, and tobacco use in children and families are needed to prevent adverse health outcomes related to tobacco use and obesity.

Sonographically Assessed Intra-Abdominal Fat And Cardiometabolic Risk Factors in Adolescents with Extreme Obesity

OBJECTIVE

The metabolic and cardiovascular risk of obesity is predominantly defined through the amount of intra-abdominal fat (IAF). Regarding this risk and the benefits of weight reduction gender-specific differences have been described. The aim of this study was to examine the gender-specific relationship between IAF assessed via ultrasound and the cardiometabolic risk profile in extremely obese adolescents before and after weight loss.

METHODS

In 107 consecutively admitted adolescents (n = 59 girls, mean age 15.4 ± 2.6 years boys and 15.1 ± 2.1 years girls, mean BMI z-score 3.2 ± 0.6 boys and 3.5 ± 0.6 girls) anthropometric and fasting laboratory chemical parameters were measured before and after an in-patient long-term therapy (mean durance 5.6 ± 2.3 months). IAF was determined by measuring the intra-abdominal depth (IAD) via ultrasound.

RESULTS

IAD was higher in boys as compared to girls (58.0 ± 22.4 mm vs. 51.3 ± 16.0 mm). IAD values were positively associated with BMI-z scores, waist circumferences, HOMA-IR and serum levels of x03B3;GT, hs-CRP and IL-6 in both genders. In boys, but not in girls, IAD was significantly correlated with systolic and diastolic blood pressure, serum levels of triglycerides, ALT as well as adiponectin and HDL-cholesterol. After a marked mean weight loss of -27.1 ± 16.2 kg (-20.1 ± 7.9%) in boys and of -20.5 ± 11.5 kg (-17.3 ± 7.1%) in girls, IAD decreased by -20.7 ± 16.2 mm (--32.4 ± 16.9%) in boys and by -18.4 ± 12,7 mm (-34.3 ± 18.4%) in girls, resulting in more pronounced ameliorations of cardiovascular risk factors in boys than in girls.

CONCLUSIONS

The present study indicates that IAF assessed by ultrasound is a good indicator for the cardiometabolic risk factor profile in extremely obese adolescents. Associations between IAF and risk factors are more pronounced in boys than in girls.

Neck Circumference as a Predictor of Adiposity among Healthy and Obese Children

BACKGROUND:

Obesity, particularly in the upper part of body, is a major health problem. Because body mass index (BMI) does not adequately describe regional adiposity, other indices of body fatness are being explored.

OBJECTIVES:

To determine if neck circumference is a valid measure of adiposity (fat distribution) among group of Egyptian children.

SUBJECTS AND METHODS:

This is a cross sectional study, included 50 obese subjects, aged 7 - 12 years recruited from Endocrine, obesity and Metabolism Pediatric Unit at Children Hospital, Cairo University and 50 healthy children, age and sex matched. All children were subjected to blood pressure assessment (systolic SBP and diastolic DBP), and anthropometric assessment (body weight, height, neck circumference (NC), waist (WC) and hip (HC) circumferences, and skin fold thicknesses at three sites: biceps, triceps and sub scapular. BMI [weight (kg)/height (m2)] was calculated.

RESULTS:

In healthy females, significant associations were detected between NC and SBP, DBP and all anthropometric measurements. However, in healthy males NC was not significantly associated with BMI, SBP and DBP. In the obese group; both sexes; insignificant association was found between NC and SBP, DBP, BMI and skinfold thickness.

CONCLUSION:

NC is related to fat distribution among normal healthy female children. However, this relation disappears with increasing adiposity. The results do not support the use of NC as a useful screening tool for childhood obesity.

Reliability tests and guidelines for B-mode ultrasound assessment of central adiposity

INTRODUCTION

Ultrasound represents a validated and relatively inexpensive diagnostic device for assessing central adiposity; however, widespread adoption has been impeded by the lack of reliable standard operating procedures.

PURPOSE

To examine the reliability of, and describe guidelines for, ultrasound-derived recording of intra-abdominal fat thickness (IAT) and maximal preperitoneal fat thickness (PFT).

METHODS

Ultrasound scans were obtained from 20 adults (50% female, 26 ± 7 years, 24·5 kg/m(2) ) on three different mornings. IAT was assessed 2 cm above the umbilicus (transverse plane) measuring from linea alba to: (i) anterior aorta, (ii) posterior aorta and (iii) anterior aspect of the vertebral column. PFT was measured from linea alba to visceral peritoneum in (i) sagittal and (ii) transverse planes, immediately over and inferior to the xiphi-sternum, respectively.

RESULTS

For IAT, the criterion intraclass correlation coefficient (ICC) of 0·75 was exceeded for measurements to anterior aorta (0·95), posterior aorta (0·94) and vertebra (0·96). The reliability coefficient expressed as a percentage of the mean (RC%) was lowest (better) for measurement to vertebrae (9·8%). For PFT, mean thickness was comparable for sagittal (1·74 cm) and transverse (1·76 cm) planes; ICC values were also comparable for both planes (0·98 vs. 0·98, respectively), as were RC% (7·5% vs. 7·1%, respectively).

CONCLUSIONS

IAT assessments to the vertebra were marginally more reliable than those to other structures. While PFT assessments were equally reliable for both measurements planes, precise probe placement was easier for the sagittal plane. Based on these findings, guidelines for the reliable measurement of central adiposity using ultrasound are presented.

Prospective Associations Between Early Long-Term Household Tobacco Smoke Exposure and Subsequent Indicators of Metabolic Risk at Age 10

INTRODUCTION

Although there are established risks associated with gestational tobacco smoke exposure, few studies have addressed the metabolic hazards of domestic exposure in early childhood. This study prospectively examines the long-term relationship between early childhood exposure to household smoke and two adiposity-related measures at age 10.

METHODS

Participants from the Quebec Longitudinal Study of Child Development birth cohort were categorized into one of three groups of early childhood household exposure to tobacco smoke over four time points (from ages 1 to 7 years): never-exposed; transient exposure; and continuous exposure. Follow-up measures of body mass index and waist circumference were independently assessed at age 10.

RESULTS

Compared to being never exposed, transient and continuous household smoke exposure predicted increases of 0.93 cm (95% confidence interval [CI] between 0.05 and 1.82 cm; P = .03) and 1.56 cm (95% CI between 0.07 and 3.05 cm; P = .04) in children's waist circumference, respectively. Children exposed to transient and continuous household smoke, compared to unexposed children, also showed 0.48 and 0.81 point increases in their body mass index, respectively, both Ps = .005. Once adjusted, for confounding variables, only transient household smoke remained associated with 43% greater odds of belonging to the overweight/obese category (95% CI between 1.12 and 1.81 cm; P < .01).

CONCLUSIONS

We found significant long-term prospective associations between home-based secondhand smoke exposure and unhealthy body fat distribution. Waist circumference in youth has become an important risk factor for obesity-related diseases in adulthood. Our findings emphasize the importance public health initiatives and parental sensitization aimed at domestic exposure reductions during the critical early childhood years.

Visceral adipose tissue measured by DXA correlates with measurement by CT and is associated with cardiometabolic risk factors in children

BACKGROUND

Visceral adipose tissue (VAT) generally demonstrates a stronger relationship with cardiometabolic risk factors than total body fat or subcutaneous adipose tissue.

OBJECTIVES

The purpose of this study was to compare VAT estimated in children by total volume dual-energy X-ray absorptiometry (DXA) with a gold standard measurement, single slice (L4-L5) computed tomography (CT).

METHODS

A total of 329 (152 females, 177 males) children ages 6-18 years (mean age 12.3 ± 3.6) and with average body mass index percentile of 54.9% (3-99%) had their VAT estimated by both CT and DXA. Linear association between methods was measured using Pearson's correlation. Multiple linear regressions compared the associations between cardiometabolic risk factors and both CT-VAT and DXA-VAT, respectively.

RESULTS

In children, DXA-VAT was correlated significantly with CT-VAT, with a stronger relationship in overweight and obese children. Multiple regression analysis showed that both estimates of VAT were significantly associated with lipids and insulin sensitivity, measured by euglycaemic-hyperinsulinaemic clamp. Additionally, DXA-VAT was associated with diastolic blood pressure, homeostasis model of insulin resistance and fasting insulin, but CT-VAT was not.

CONCLUSION

In children, total volume DXA-VAT and single slice CT-VAT are significantly correlated and each demonstrates similar associations with cardiometabolic risk factors. This suggests that DXA is a useful and valid method for estimation of VAT in children.

Measurement site influences abdominal subcutaneous and visceral adipose tissue in obese adolescents before and after exercise

BACKGROUND/OBJECTIVES

The objective of this study was to determine if abdominal adipose tissue (AT) measurement site influences the association between baseline and change in abdominal subcutaneous (ASAT) and visceral AT (VAT), and metabolic risk factors in obese adolescents.

METHODS

Fifty-five obese adolescents (14.9 ± 1.7 years; 51% male; 42% white) participated in an aerobic or resistance exercise intervention three times/week for 3 months. We compared the association between changes in abdominal AT area (spanning 5 cm below to 15 cm above L4-L5) and volume measured by magnetic resonance imaging with concomitant changes in metabolic risk.

RESULTS

All AT areas were significantly (p < 0.05) correlated with the respective volume at baseline and follow-up. Baseline VAT areas at 5 and 10 cm above L4-L5 were more strongly associated with VAT volume than VAT area at L4-L5 (p < 0.05). After the intervention, changes in the area at 5 and 10 cm above L4-L5 were more strongly associated with changes in AT volumes than changes in L4-L5 (p < 0.05). Changes in abdominal AT volumes were more strongly associated with insulin area under the curve than any single-slice abdominal AT area.

CONCLUSIONS

The measurement site for abdominal AT has significant influence on the relationships with total VAT or ASAT and metabolic risk factors in obese adolescents before and after an exercise intervention.

Sexual dimorphism in relation to adipose tissue and intrahepatocellular lipid deposition in early infancy

Sexual dimorphism in adiposity is well described in adults, but the age at which differences first manifest is uncertain. Using a prospective cohort, we describe longitudinal changes in directly measured adiposity and intrahepatocellular lipid (IHCL) in relation to sex in healthy term infants. At median ages of 13 and 63 days, infants underwent quantification of adipose tissue depots by whole-body magnetic resonance imaging and measurement of IHCL by in vivo proton magnetic resonance spectroscopy. Longitudinal data were obtained from 70 infants (40 boys and 30 girls). In the neonatal period girls are more adipose in relation to body size than boys. At follow-up (median age 63 days), girls remained significantly more adipose. The greater relative adiposity that characterises girls is explained by more subcutaneous adipose tissue and this becomes increasingly apparent by follow-up. No significant sex differences were seen in IHCL. Sex-specific differences in infant adipose tissue distribution are in keeping with those described in later life, and suggest that sexual dimorphism in adiposity is established in early infancy.

The Relation between Visceral and Subcutaneous Fat to Bone Mass among Egyptian Children and Adolescents

BACKGROUND: The relation between fat distribution and bone mass is still being debated in children and adolescents.AIM: To verify the influence of both visceral and subcutaneous fat on bone mass among Egyptian children and adolescents.SUBJECTS AND METHODS: The study involved 78 (38 boys and 40 girls) individuals from children (42) and adolescents (36), aged 8-17 years. They were divided into 2 age groups: children group (20 boys and 22 girls) aged 8-12 years and adolescent group (18 boys and 18 girls) aged 13-17 years. Anthropometric measurements, visceral and subcutaneous fat (measured by ultrasound), body composition, BMD and BMC (Measured by DXA), were attempted.RESULTS: Among children, significant positive correlations between visceral fat; in males; and subcutaneous fat; in females; with total BMC, BMD and its Z-score were revealed. After exclusion of age effect, the association between visceral fat in females with total BMD and its Z-score and lumbar BMD-Z-score became significant.  For adolescents, no correlation was observed between either visceral or subcutaneous fat with any parameter of bone mass.CONCLUSIONS: Visceral and subcutaneous fat had significant positive association with bone mass in children; males and females respectively. On the contrary such association disappeared during adolescence.

Effects of recombinant human growth hormone (rhGH) administration on body composition and cardiovascular risk factors in obese adolescent girls

Background

Obesity is associated with a relative deficiency of growth hormone, which is predictive of greater visceral fat and markers of cardiovascular risk. The study’s purpose was to use recombinant human growth hormone (rhGH) as a physiologic probe to assess the effects of reversing obesity-related GH deficiency on body composition, cardiovascular risk markers, and insulin resistance.

Methods

22 obese girls 13–21 years old were followed for a randomized 6-month trial of rhGH vs. placebo/no treatment. At baseline and 6-months, DXA was performed for body composition, MRI to measure visceral, subcutaneous and total adipose tissue (VAT, SAT and TAT), and fasting blood drawn for IGF-1, inflammatory cardiovascular risk markers [soluble intercellular adhesion molecule (sICAM), high sensitivity CRP], lipids and HbA1C. An oral glucose tolerance test (OGTT) was performed. Twelve girls completed the 6-month visit. Baseline and mean 6-month change were compared between the groups using the Student t-test and the relationship between variables was determined through multiple regression analysis.

Results

After 6-months, the rhGH group maintained IGF-1 levels, and had decreases in total cholesterol (p = 0.03), sICAM-1 (p = 0.04) and HbA1C (p = 0.03) compared to placebo/no treatment. The rhGH group trended towards greater decreases in LDL and 2-hour OGTT glucose. Glucose tolerance did not worsen with rhGH administration.

Conclusions

Administering rhGH in small doses is able to stabilize IGF-1 levels in obesity. We have also shown that rhGH administration leads to an improvement in some markers of cardiovacular risk with without adversely affecting glucose tolerance.

Trial registration

Clinical Trial Registration Number: NCT01169103.

Pre-Adolescent Cardio-Metabolic Associations and Correlates: PACMAC methodology and study protocol

INTRODUCTION

Although cardiovascular disease is typically associated with middle or old age, the atherosclerotic process often initiates early in childhood. The process of atherosclerosis appears to be occurring at an increasing rate, even in pre-adolescents, and has been linked to the childhood obesity epidemic. This study will investigate the relationships between obesity, lifestyle behaviours and cardiometabolic health in pre-pubescent children aged 8-10 years, and investigates whether there are differences in the correlates of cardiometabolic health between Māori and Caucasian children. Details of the methodological aspects of recruitment, inclusion/exclusion criteria, assessments, statistical analyses, dissemination of findings and anticipated impact are described.

METHODS AND ANALYSIS

Phase 1: a cross-sectional study design will be used to investigate relationships between obesity, lifestyle behaviours (nutrition, physical activity/fitness, sleep behaviour, psychosocial influences) and cardiometabolic health in a sample of 400 pre-pubescent (8-10 years old) children. Phase 2: in a subgroup (50 Caucasian, 50 Māori children), additional measurements of cardiometabolic health and lifestyle behaviours will be obtained to provide objective and detailed data. General linear models and logistic regression will be used to investigate the strongest correlate of (1) fatness; (2) physical activity; (3) nutritional behaviours and (4) cardiometabolic health.

ETHICS AND DISSEMINATION

Ethical approval will be obtained from the New Zealand Health and Disabilities Ethics Committee. The findings from this study will elucidate targets for decreasing obesity and improving cardiometabolic health among preadolescent children in New Zealand. The aim is to ensure an immediate impact by disseminating these findings in an applicable manner via popular media and traditional academic forums. Most importantly, results from the study will be disseminated to participating schools and relevant Māori health entities.

Cardiometabolic risk assessments by body mass index z-score or waist-to-height ratio in a multiethnic sample of sixth-graders

Convention defines pediatric adiposity by the body mass index z-score (BMIz) referenced to normative growth charts. Waist-to-height ratio (WHtR) does not depend on sex-and-age references. In the HEALTHY Study enrollment sample, we compared BMIz with WHtR for ability to identify adverse cardiometabolic risk. Among 5,482 sixth-grade students from 42 middle schools, we estimated explanatory variations (R²) and standardized beta coefficients of BMIz or WHtR for cardiometabolic risk factors: insulin resistance (HOMA-IR), lipids, blood pressures, and glucose. For each risk outcome variable, we prepared adjusted regression models for four subpopulations stratified by sex and high versus lower fatness. For HOMA-IR, R² attributed to BMIz or WHtR was 19%–28% among high-fatness and 8%–13% among lower-fatness students. R² for lipid variables was 4%–9% among high-fatness and 2%–7% among lower-fatness students. In the lower-fatness subpopulations, the standardized coefficients for total cholesterol/HDL cholesterol and triglycerides tended to be weaker for BMIz (0.13–0.20) than for WHtR (0.17–0.28). Among high-fatness students, BMIz and WHtR correlated with blood pressures for Hispanics and whites, but not black boys (systolic) or girls (systolic and diastolic). In 11-12 year olds, assessments by WHtR can provide cardiometabolic risk estimates similar to conventional BMIz without requiring reference to a normative growth chart.

Maternal tobacco smoke increased visceral adiposity and serum corticosterone levels in adult male rat offspring

BACKGROUND

Maternal tobacco smoke (MTS) predisposes human and rat offspring to visceral obesity in early adulthood. Glucocorticoid excess also causes visceral obesity. We hypothesized that in utero MTS would increase visceral adiposity and alter the glucocorticoid pathway in young adult rats.

METHODS

We developed a novel model of in utero MTS exposure in pregnant rats by exposing them to cigarette smoke from E11.5 to term. Neonatal rats were cross-fostered to control dams and weaned to standard rat chow through young adulthood (postnatal day 60).

RESULTS

We demonstrated increased visceral adiposity (193%)*, increased visceral adipose 11-β hydroxysteroid dehydrogenase 1 mRNA (204%)*, increased serum corticosterone (147%)*, and no change in glucocorticoid receptor protein in adult male MTS rat offspring. Female rats exposed to MTS in utero demonstrated no change in visceral or subcutaneous adiposity, decreased serum corticosterone (60%)*, and decreased adipose glucocorticoid receptor protein (66%)*. *P < 0.05.

CONCLUSION

We conclude that in utero MTS exposure increased visceral adiposity and altered in the glucocorticoid pathway in a sex-specific manner. We speculate that in utero MTS exposure programs adipose dysfunction in adult male rat offspring via alteration in the glucocorticoid pathway.

Ethnic and sex differences in visceral, subcutaneous, and total body fat in children and adolescents

OBJECTIVE

This study investigated ethnic and sex differences in the distribution of fat during childhood and adolescence.

DESIGN AND METHODS

A cross-sectional sample (n = 382), aged 5-18 years, included African American males (n = 84), White males (n = 96), African American females (n = 118), and White females (n = 84). Measures for total body fat (TBF) mass and abdominal adipose tissue (total volume and L4-L5 cross-sectional area) for both subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) depots were assessed by dual-energy X-ray absorptiometry and magnetic resonance image, respectively. Analyses of covariance (ANCOVAs) were used to determine ethnic and sex differences in TBF (adjusted for age) and ethnic and sex differences in SAT and VAT (adjusted for both age and TBF).

RESULTS

Age-adjusted TBF was greater in African Americans (P = 0.017) and females (P < 0.0001) compared with Whites and males, respectively. In age- and TBF-adjusted ANCOVAs, no differences were found in the SAT. The VAT volume was, however, greater in Whites (P < 0.0001) and males (P < 0.0001) compared with African Americans and females, respectively. Similar patterns were observed in SAT and VAT area at L4-L5.

CONCLUSIONS

The demonstrated ethnic and sex differences are important confounders in the prevalence of obesity and in the assignment of disease risk in children and adolescents.

A review of randomized controlled trials of aerobic exercise training on fitness and cardiometabolic risk factors in obese adolescents

Aerobic training is the most prescribed exercise modality for the management of pediatric obesity. There is strong evidence that it decreases waist circumference, percent body fat and visceral fat, increases cardiorespiratory fitness, and decreases blood pressure in obese adolescents. However, the independent effects of aerobic exercise training on other cardiometabolic risk factors (ie, insulin resistance markers, plasma lipid levels, and inflammatory markers) are limited and yield inconsistent findings. Our article reviews randomized controlled trials evaluating the effects of aerobic exercise training on body composition, fitness, lipid levels, and insulin resistance in obese adolescents (aged 13-18 years) and outlines future research directions for this population.

Oxidative stress and cardiovascular risk in overweight children in an exercise intervention program

BACKGROUND

This study aimed to determine whether oxidative stress was related to cardiovascular risk indices in children, and whether an exercise intervention would reduce oxidative stress.

METHODS

A randomized trial of two different doses of exercise and a no-exercise control group included 112 overweight and obese children, 7-11 years old. Plasma isoprostane levels were obtained at baseline and after the intervention. Cross-sectional analysis of oxidative stress and metabolic markers at baseline was performed. The effect of the exercise training on oxidative stress was tested.

RESULTS

Lower isoprostane levels were observed in blacks. At baseline, isoprostane was positively related to measures of fatness (BMI, waist circumference, percent body fat), insulin resistance and β-cell function (fasting insulin, insulin area under the curve, Matsuda index, disposition index, oral disposition index), and several lipid markers (low-density lipoprotein, triglycerides, total cholesterol), and inversely with fitness [peak oxygen consumption (VO(2))], independent of race, sex, and cohort. No relation was found with visceral fat, blood pressure, or glycemia. Independent of percent body fat, isoprostane predicted triglycerides, β=0.23, total cholesterol-to-high-density lipoprotein (TC/HDL) ratio, β=0.23, and insulin resistance (insulin area under the curve, β=0.24, Matsuda index, β=-0.21, oral disposition index, β=0.33). Exercise did not reduce oxidative stress levels, despite reduced fatness and improved fitness in these children.

CONCLUSIONS

Isoprostane levels were related to several markers of cardiovascular risk at baseline; however, despite reduced fatness and improved fitness, no effect of exercise was observed on isoprostane levels. To our knowledge, this is the first report in children to demonstrate a correlation of oxidative stress with disposition index, fitness, and TC/HDL ratio, the first to test the effect on oxidative stress of an exercise intervention that reduced body fat, and the first such exercise intervention study to include a substantial proportion of black children.

Tanner Staging of Secondary Sexual Characteristics and Body Composition, Blood Pressure, and Insulin in Black Girls

OBJECTIVE

To assess Tanner staging (breast and pubic hair development) and its relationship to measures of body composition, blood pressure, and fasting insulin and glucose in young black girls.

RESEARCH METHODS AND PROCEDURES

Subjects were 138 black girls, 8 to 12 years of age, recruited from elementary schools in low socioeconomic status neighborhoods. Exclusion criteria included the presence of any acute/chronic medical conditions. Pubertal stages were assessed by one of two pediatricians and analyzed individually, as well as with a composite index (prepubertal, pubertal/premenarcheal, or pubertal/menarcheal). Glucose and insulin were measured after a 12-hour fast. Measures of body composition included height, weight, BMI, waist and hip circumferences, fat mass, fat-free soft tissue, bone mineral density (DXA), and visceral adipose tissue (magnetic resonance imaging). Resting systolic and diastolic blood pressure were measured by Dinamap.

RESULTS

With age in the model, breast development explained significant proportions of the variance in height, weight, fat-free soft tissue, bone mineral density, and insulin. Adding pubic hair development or menarche to those models did not significantly increase the proportion of variance that was explained by breast development. Furthermore, using a composite index of pubertal staging explained a smaller proportion of the variance compared with breast development alone.

DISCUSSION

Combined with age, breast development was a better predictor of body composition and fasting insulin than was pubic hair development or a composite index of pubertal staging.

Ethnic and sex differences in body fat and visceral and subcutaneous adiposity in children and adolescents

Body fat and the specific depot where adipose tissue (AT) is stored can contribute to cardiometabolic health risks in children and adolescents. Imaging procedures including magnetic resonance imaging and computed tomography allow for the exploration of individual and group differences in pediatric adiposity. This review examines the variation in pediatric total body fat (TBF), visceral AT (VAT) and subcutaneous AT (SAT) due to age, sex, maturational status and ethnicity. TBF, VAT and SAT typically increase as a child ages, though different trends emerge. Girls tend to accumulate more TBF and SAT during and after puberty, depositing fat preferentially in the gynoid and extremity regions. In contrast, pubertal and postpubertal boys tend to deposit more fat in the abdominal region, particularly in the VAT depot. Sexual maturation significantly influences TBF, VAT and SAT. Ethnic differences in TBF are mixed. VAT tends to be higher in white and Hispanic youth, whereas SAT is typically higher in African American youth. Asian youth typically have less gynoid fat but more VAT than whites. Obesity per se may attenuate sex and ethnic differences. Particular health risks are associated with high amounts of TBF, VAT and SAT, including insulin resistance, hepatic steatosis, metabolic syndrome and hypertension. These risks are affected by genetic, biological and lifestyle factors including physical activity, nutrition and stress. Synthesizing evidence is difficult as there is no consistent methodology or definition to estimate and define depot-specific adiposity, and many analyses compare SAT and VAT without controlling for TBF. Future research should include longitudinal examinations of adiposity changes over time in representative samples of youth to make generalizations to the entire pediatric population and examine variation in organ-specific body fat.

Exercise dose and diabetes risk in overweight and obese children: a randomized controlled trial

CONTEXT

Pediatric studies have shown that aerobic exercise reduces metabolic risk, but dose-response information is not available.

OBJECTIVES

To test the effect of different doses of aerobic training on insulin resistance, fatness, visceral fat, and fitness in overweight, sedentary children and to test moderation by sex and race.

DESIGN, SETTING, AND PARTICIPANTS

Randomized controlled efficacy trial conducted from 2003 through 2007 in which 222 overweight or obese sedentary children (mean age, 9.4 years; 42% male; 58% black) were recruited from 15 public schools in the Augusta, Georgia, area.

INTERVENTION

Children were randomly assigned to low-dose (20 min/d; n = 71) or high-dose (40 min/d; n = 73) aerobic training (5 d/wk; mean duration, 13 [SD, 1.6] weeks) or a control condition (usual physical activity; n = 78).

MAIN OUTCOME MEASURES

The prespecified primary outcomes were postintervention type 2 diabetes risk assessed by insulin area under the curve (AUC) from an oral glucose tolerance test, aerobic fitness (peak oxygen consumption [VO2]), percent body fat via dual-energy x-ray absorptiometry, and visceral fat via magnetic resonance, analyzed by intention to treat.

RESULTS

The study had 94% retention (n = 209). Most children (85%) were obese. At baseline, mean body mass index was 26 (SD, 4.4). Reductions in insulin AUC were larger in the high-dose group (adjusted mean difference, -3.56 [95% CI, -6.26 to -0.85] × 10(3) μU/mL; P = .01) and the low-dose group (adjusted mean difference, -2.96 [95% CI, -5.69 to -0.22] × 10(3) μU/mL; P = .03) than the control group. Dose-response trends were also observed for body fat (adjusted mean difference, -1.4% [95% CI, -2.2% to -0.7%]; P < .001 and -0.8% [95% CI, -1.6% to -0.07%]; P = .03) and visceral fat (adjusted mean difference, -3.9 cm3 [95% CI, -6.0 to -1.7 cm3]; P < .001 and -2.8 cm3 [95% CI, -4.9 to -0.6 cm3]; P = .01) in the high- and low-dose vs control groups, respectively. Effects in the high- and low-dose groups vs control were similar for fitness (adjusted mean difference in peak VO2, 2.4 [95% CI, 0.4-4.5] mL/kg/min; P = .02 and 2.4 [95% CI, 0.3-4.5] mL/kg/min; P = .03, respectively). High- vs low-dose group effects were similar for these outcomes. There was no moderation by sex or race.

CONCLUSION

In this trial, after 13 weeks, 20 or 40 min/d of aerobic training improved fitness and demonstrated dose-response benefits for insulin resistance and general and visceral adiposity in sedentary overweight or obese children, regardless of sex or race.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00108901.

Use of MRI and CT for fat imaging in children and youth: what have we learned about obesity, fat distribution and metabolic disease risk?

Childhood obesity is a matter of great concern for public health. Efforts have been made to understand its impact on health through advanced imaging techniques. An increasing number of studies focus on fat distribution and its associations with metabolic risk, in interaction with genetics, environment and ethnicity, in children. The present review is a qualitative synthesis of the existing literature on visceral and subcutaneous abdominal, intrahepatic and intramuscular fat. Our search revealed 80 original articles. Abdominal as well as ectopic fat depots are prevalent already in childhood and contribute to abnormal metabolic parameters, starting early in life. Visceral, hepatic and intramuscular fat seem to be interrelated but their patterns as well as their independent contribution on metabolic risk are not clear. Some ethnic-specific characteristics are also prevalent. These results encourage further research in childhood obesity by using imaging techniques such as magnetic resonance imaging and computed tomography. These imaging methods can provide a better understanding of fat distribution and its relationships with metabolic risk, compared to less detailed fat and obesity assessment. However, studies on bigger samples and with a prospective character are warranted.

Early childhood television viewing predicts explosive leg strength and waist circumference by middle childhood

BACKGROUND

The relationship between early childhood television viewing and physical fitness in school age children has not been extensively studied using objective outcome measures.

METHODS

Using a sample of 1314 children from the Québec Longitudinal Study of Child Development, we examine the association between parental reports of weekly hours of television viewing, assessed at 29 and 53 months of age, and direct measures of second grade muscular fitness using performances on the standing long jump test (SLJ) and fourth grade waist circumference.

RESULTS

Controlling for many potentially confounding child and family variables, each hour per week of television watched at 29 months corresponded to a .361 cm decrease in SLJ, 95% CI between -.576 and -.145. A one hour increase in average weekly television exposure from 29 to 53 months was associated with a further .285 cm reduction in SLJ test performance, 95% CI between -.436 and -.134 cm and corresponded to a .047 cm increase in waistline circumference, 95% CI between .001 and .094 cm.

INTERPRETATION

Watching television excessively in early childhood, may eventually compromise muscular fitness and waist circumference in children as they approach pubertal age.

Body mass index, waist circumference, body fat, fasting blood glucose in a sample of moroccan adolescents aged 11-17 years

Objectives. The study aimed to assess the relationship between body fat and each of body mass index (BMI) and waist circumference (WC), and to test the effectiveness of fat mass (FM), percent of body fat (PBF), BMI, and WC in predicting high levels of fasting blood glucose (FBG). Methods. A total of 167 adolescents aged 11–17 years were recruited from Rabat region. BMI and WC were determined using standard equipments. FM and PBF were derived from isotope dilution technique. FBG was determined by the hexokinase method. Results. Regardless of the weight status, BMI showed a strong positive correlation with FM and PBF in both genders. WC was significantly correlated with FM in boys and girls, and with PBF in different groups of girls and boys of the study sample. However, there was no significant relationship between WC and PBF in normal weight and overweight-obese groups of boys. FBG was highly correlated with FM and PBF in girls of the study sample and in overweight-obese girls. Similar significant relationship between FBG and both BMI and WC was observed in overweight-obese girls, while there was no significant association between FBG and other variables in boys and normal-weight girls. Conclusion. BMI and WC were closely associated with FM and PBF, respectively. However, the degree of these associations depends on gender and weight status. BMI may provide a better proxy estimate of overall adiposity than WC; nevertheless, both of them would appear to be a reasonable surrogate for FM and PBF as screening tools to identify adolescents at risk of developing excess body fat and high level of FBG.

Cardiometabolic biomarkers in young black girls: relations to body fatness and aerobic fitness, and effects of a randomized physical activity trial

There is little evidence from randomized trials showing that physical activity alone influences biomarker profiles in youths. This study tested two hypotheses: (i) that elevated body fatness and poor fitness would be associated with unfavorable levels of cardiometabolic biomarkers in 8–12-y-old black girls (n = 242) and (ii) that a 10-mo PA intervention would have favorable effects on the fatness-related cardiometabolic biomarkers. At baseline, all fatness indices (i.e., percent body fat, visceral adipose tissue, BMI, and waist circumference) were significantly (P < 0.05) associated with unfavorable levels of insulin, glucose, systolic BP, diastolic BP, triglycerides, C-reactive protein (CRP), and fibrinogen. Aerobic fitness was significantly (P < 0.05) associated with favorable levels of insulin, CRP, fibrinogen, and HDL₂. The PA intervention had significant and favorable effects on fitness, fatness, and two biomarkers—resting heart rate and LDL cholesterol. More research is needed to clarify what types of interventions can enhance the cardiometabolic health of youths.

Association of body fat percentage with lipid concentrations in children and adolescents: United States, 1999-2004

BACKGROUND

BMI is one factor that is used to determine a child's eligibility for lipid screening and treatment. BMI, which is an indirect measure of body fat, may inadequately represent the biological effect of body fat percentage on lipid concentrations.

OBJECTIVE

We examined the relation between directly measured body fat percentage and lipid concentrations in a representative sample of US youths.

DESIGN

Data from 7821 participants aged 8-19 y from the 1999-2004 NHANES were analyzed. Body fat percentage was measured by dual-energy X-ray absorptiometry. Total and HDL-cholesterol concentrations were measured in serum. Serum triglyceride and LDL-cholesterol concentrations were measured in a subsample of 2661 fasting NHANES participants aged 12-19 y. Prevalences of adverse total cholesterol (>200 mg/dL), LDL cholesterol (>130 mg/dL), triglycerides (>150 mg/dL), and HDL cholesterol (<35 mg/dL) were measured.

RESULTS

Approximately 10.0% [±0.7% (SE)] of participants had high total cholesterol, 7.0 ± 0.4% of participants had low HDL cholesterol, 9.7 ± 1.0% of participants had high triglycerides, and 7.6 ± 0.7% of participants had high LDL cholesterol. Prevalence of adverse total cholesterol, HDL cholesterol, triglycerides, and LDL cholesterol in US youths with high adiposity (greater than or equal to the age- and sex-specific 75th percentile of body fat percentage) was significantly greater (P < 0.01) than for participants without high adiposity. In multiple linear regressions adjusted for age, survey period, and race-ethnicity, the variance in lipid concentrations explained by body fat percentage was 2-20% (P < 0.001).

CONCLUSION

Adverse lipid concentrations and high adiposity are significantly associated in youths.

UAE population reference standard charts for body mass index and skinfold thickness, at ages 0-18 years

AIMS

To determine a range of anthropometric measurements including skinfold thickness measurements in four different areas of the body, to construct population growth charts for body mass index (BMI), skinfolds, and to compare these with growth charts from other countries. One aim was also to validate body fat charts derived from skinfold thickness.

METHODS

A national cross-sectional growth survey of children, 0-18 years old, was conducted using multistage stratified random sampling. The sample size included at least 200 children in each age-sex group. Height, weight, biceps skinfold, triceps skinfold, subscapular skinfold, suprailiac skinfold, and mid-upper-arm circumference were measured in each child. We describe correlation, standard deviation scores relative to the other standards, and calculation of body density in the United Arab Emirates population. We determined whether any of the above is a good indicator of fatness in children.

RESULTS

BMI, upper-arm circumference, sum of four skinfolds, and percentage body fat charts were constructed using the LMS method of smoothing. BMI was very significantly correlated with sum of skinfold thicknesses, and mid-upper-arm circumference. Prevalence of obesity and overweight in ages 13-17 years was respectively 9.94% and 15.16% in females and 6.08% and 14.16% in males. Derived body fat charts were found not to be accurate.

CONCLUSION

A national BMI, upper-arm circumference, and sum of four skinfolds chart has been constructed that can be used as a reference standard for the United Arab Emirates. Sum of four skinfold thickness charts can be used as crude determinants of adiposity in children, but derived body fat charts were shown to be inaccurate.