Visceral abdominal fat is correlated with whole-body fat and physical activity among 8-y-old children at risk of obesity

Physical activity, screen time and body composition in 13-year-old adolescents: The Generation R Study

BACKGROUND

Body composition between prepubertal children and adolescents varies, and it is unclear how physical activity and sedentary behaviour affect adolescent body composition.

OBJECTIVES

This study aimed to examine the associations of physical activity and screen time with overall and specific fat depots in the general adolescent population.

METHODS

In a population-based prospective cohort study, among 3258 adolescents aged 13 years, physical activity and screen time were assessed via self-report questionnaires. Body mass index, dual-energy X-ray absorptiometry-based measures (i.e. fat mass and lean body mass) and magnetic resonance imaging-based measures (i.e. abdominal subcutaneous and visceral fat mass) were obtained.

RESULTS

After adjusting for social-demographic and growth-related factors, each additional hour of daily physical activity was associated with lower fat mass, abdominal visceral fat mass and higher lean body mass (all p < 0.05). However, these associations were not observed in the longitudinal analyses. Each additional hour of daily screen time was associated with higher body mass index, fat mass, abdominal subcutaneous and visceral fat mass (all p < 0.05), which were consistent with the longitudinal analyses.

CONCLUSION

Adolescents with higher physical activity and lower screen time had lower levels of adiposity both at the general and visceral levels.

High uric acid levels in overweight and obese children and their relationship with cardiometabolic risk factors: what is missing in this puzzle?

OBJECTIVES

The prevalence of hyperuricemia, a common disorder, has been increasing. Moreover, the association between obesity, serum uric acid levels, and cardiometabolic markers in children is unclear. Therefore, this study aimed to analyze the inter-relationships between these factors in a sample of children aged 6-12 years.

METHODS

We evaluated 764 children and stratified them according to their body mass index (BMI). Blood pressure and uric acid, creatinine, lipid, and glycemic profiles were evaluated, and the estimated glomerular filtration rate (eGFR) and the homeostatic model assessment for insulin resistance (HOMA-IR) index were calculated.

RESULTS

There was a significant linear trend of increasing systolic blood pressure (SBP), diastolic blood pressure (DBP), triglycerides (TG), total cholesterol, low-density lipoprotein cholesterol (LDLc), uric acid, insulin levels, and HOMA-IR index values corresponding with overweight and obese groups; however, high-density lipoprotein cholesterol (HDLc) levels decreased with increasing obesity. The mean creatinine level and eGFR were similar across all BMI groups. Uric acid levels were significantly correlated with BMI (r=0.527), waist circumference (r=0.580), SBP (r=0.497), DBP (r=0.362), TG (r=0.534), total cholesterol (r=0.416), LDLc (r=0.286), HDLc (r=-0.248), insulin (r=0.613), and HOMA-IR index (r=0.607). Multiple regression analyses showed that BMI (B=0.071; SE=0.012; p<0.001), TG (B=0.004; SE=0.001; p<0.001), LDLc (B=0.003; SE=0.001; p=0.006), and insulin (B=0.066; SE=0.007; p<0.001) (R²=0.460) were significant predictors of increased uric acid levels and explained 46% of the variability in uric acid in these children.

CONCLUSIONS

Our findings suggest that overweight or obese children are more likely to have higher uric acid levels. Moreover, several cardiometabolic risk factors were strongly associated with high uric acid levels.

Precision of the Hologic DXA in the Assessment of Visceral Adipose Tissue

INTRODUCTION

Visceral fat, also known as visceral adipose tissue (VAT), has been the focus of intensive research over the past several yr, as ground breaking studies have investigated its possible role in predicting long-term cardiac dysfunction, hypertension, and diabetes. Historically, magnetic resonance imaging and computed tomography were the instruments of choice for visceral fat quantification. However, with the introduction of visceral fat assessment software for Dual-energy X-ray Absorptiometry (DXA) scanners, DXA's use for VAT assessment has become increasingly common. To effectively utilize DXA in future VAT research studies, information about their precision and accuracy must be known. This study provides novel information regarding the precision of the Hologic Horizon DXA scanner in the assessment of VAT.

METHODS

Sixty individuals (32.7 ± 17.1 yr, 51% male, 40% with body mass index (BMI) > 25 kg/m²) above the age of 16 years were recruited to participate in this study. Subjects found to be pregnant, have a lumbar vertebral compression fracture, nonremovable metal implants in the abdomen, or scoliosis/lordosis/kyphosis were excluded from the study. All subjects underwent 3 consecutive whole body scans on a Hologic Horizon A DXA scanner.

RESULTS

VAT mass ranged from 102 g to 1454 g. VAT precision improved with increasing BMI (p = 0.025): coefficient of variation (%CV) was 15.2% for underweight subjects (n = 2), 7.1% for healthy subjects (n = 34), 6.4% for overweight subjects (n = 18), and 4.7% for obese subjects (n = 6).

CONCLUSIONS

VAT measurement by Hologic DXA displays a satisfactory level of precision in individuals with a BMI of >18.5 kg/m². Precision was found to be higher in those with the greatest risk of cardio-metabolic dysfunction (individuals with high VAT). Due to its low cost, brief examination time, noninvasiveness, and limited radiation exposure, DXA may be considered the tool of choice for VAT determination in future studies.

Parenting Advice School-Age Kids Offer to Parents to Promote Healthier Child Weight-Related Behaviors

OBJECTIVE

To explore parenting advice children would provide to help parents encourage positive health-related behaviors by children.

DESIGN

Focus group discussions were conducted, and children shared the advice they would provide parents to help them encourage healthy weight-related behaviors (ie, diet, physical activity, and sleep) for children.

SETTING

Focus groups (n = 65) were conducted in 3 states (Florida, New Jersey, and West Virginia).

PARTICIPANTS

School-age children (n = 194) between the ages of 6 and 11 years old.

PHENOMENON OF INTEREST

What parenting practices are recommended by children, and are they in line with best-practice guidelines?

ANALYSIS

Focus group data were analyzed to identify themes and trends.

RESULTS

Children's recommendations were congruent with authoritative parenting styles (ie, high levels of warmth and control). Most of the advice shared by children aligned with recommended parent practices (ie, responsive feeding, facilitation, environmental restructuring, parent modeling, and encouragement). However, not all of the children's advice aligned with best practices guidelines (ie, use of food rewards and deception).

CONCLUSIONS AND IMPLICATIONS

Future nutrition education programs may be strengthened by helping parents adopt best practices for promoting healthy child behaviors. Furthermore, teaching children about recommended child feeding parenting practices may help protect future generations by preparing children to care for younger siblings or raise their children using best parenting practices.

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.

Greater Reduction in Abdominal Than in Upper Arms Subcutaneous Fat in 10- to 12-Year-Old Tennis Players: A Volumetric MRI Study

Background: Little is known about the impact of long term participation in sports and subcutaneous fat volume in children. This study aimed at determining whether tennis participation is associated with lower subcutaneous adipose tissue volume (SATv) in the abdominal and upper extremities in children. Methods: Magnetic resonance imaging (MRI) was used to determine the SATv stored in the abdominal region and upper arms in seven tennis players and seven inactive children matched by height and age (147 cm and 10.9 years). All participants were in Tanner stage 1 or 2. Results: Playing tennis was associated with 48% (P = 0.001) lower abdominal SATv and 17-18% (P > 0.05) lower upper arms SATv compared to controls. The ratio between abdominal/upper arms SATv was larger in the controls vs. tennis players (69% P = 0.001). The SATv was similar in the dominant and non-dominant arm within each group. Conclusion: Playing tennis during childhood is associated with reduced SATv in the abdominal region and a more favorable regional distribution of fat. Despite the large amount of contractile activity of the playing (dominant) arm, there was no indication of between-arms differences in SATv.

Association of time of obesity onset with comorbidities in treatment-seeking men and women with severe obesity

OBJECTIVES

Early obesity onset is a risk factor for specific comorbidities in adulthood, but whether this relationship is present in men and women with severe obesity is unknown. This study aimed to examine whether obesity onset in childhood or adolescence, as compared with adulthood, is associated with higher odds of comorbidities in men and women with severe obesity.

METHODS

A cross-sectional study of treatment-seeking men and women with severe obesity attending a tertiary care centre in Norway, from 2006 to 2017, was performed.

RESULTS

A total of 4,583 participants (69.13% women) were included. Almost all men (99.69%) and women (99.18%) suffered from ≥1 comorbidities. Compared with women, men were older (mean [SD]) (45.54 [12.14] vs. 42.56 [12.00] years, p < 0.001) and had higher body mass index (44.06 [6.16] vs. 43.39 [5.80] kg m-2, p < 0.001). The most prevalent comorbidities were non-alcoholic fatty liver disease, dyslipidaemia and hypertension among men and dyslipidaemia, non-alcoholic fatty liver disease and joint pain among women. After current age and body mass index were adjusted, childhood onset of obesity (0-11 years), compared with adult onset (>20 years), was associated with lower odds (OR [95% CI]) of obstructive sleep apnoea (OSA) in men (0.69 [0.53, 0.91], p < 0.01) and higher odds of OSA (1.49 [1.16, 1.91], p < 0.01) in women, and the interaction was significant (p < 0.01). Childhood onset of obesity was also associated with higher odds of coronary heart disease in men (1.82 [1.15, 2.89], p = 0.01) and type 2 diabetes in women (1.25 [1.01, 1.54], p = 0.04).

CONCLUSION

Childhood onset of obesity was associated with higher odds of coronary heart disease in men and OSA and type 2 diabetes in women, but with lower odds of OSA in men.

Anthropometric indices as surrogates for estimating abdominal visceral and subcutaneous adipose tissue: A meta-analysis with 16,129 participants

AIM

To seek anthropometric indices that estimate visceral and subcutaneous adipose tissue (VAT and SAT) by meta-analysis and comparing the predictive efficacy based on different characteristics of participants.

METHODS

PubMed, PubMed Central, Web of Science, China National Knowledge Infrastructure and Wanfang databases were searched for publications containing correlation coefficients of VAT and/or SAT with waist circumference (WC) and/or body mass index (BMI). The overall or subgroup pooled results were analyzed by meta and metafor packages of R with random effects model. MedCalc software was used to compare the correlation coefficients between groups.

RESULTS

Twenty-nine publications were included in this meta-analysis. The correlation coefficients of VAT-WC, VAT-BMI, SAT-WC and SAT-BMI for total studies were between 0.640 and 0.785. The correlation of VAT with WC was larger than that with BMI (Z = 11.664, P < 0.001). Meanwhile, the correlation coefficients of VAT-WC were statistically different among different age groups, areas, ethnicities, body shapes, scanning levels, units and instruments of measuring VAT (P < 0.05). The overall correlation of SAT with BMI was larger than that with WC (Z = 3.805, P < 0.001). The subgroups' correlation coefficients of SAT-BMI showed statistical differences between genders, age groups, areas, ethnicities, body shapes, scanning levels, units (cm² and cm³) and instruments of measuring SAT (P < 0.05).

CONCLUSIONS

WC may be a common and simple surrogate for estimating VAT, and BMI for SAT, especially in Europeans, but not in the aged people.

Impact of Dietary, Socioeconomic, and Physical Factors on Obese and Overweight Schoolchildren Living in Sidi-Bel-Abbes (West of Algeria) and Ain Defla (Centre)

Background and aims: The aim of the current study was to assess the impact of environmental factors; food, socio-economic, and physical activity, on a group of obese children living in Ain-Defla (Center Algeria) and Sidi-Bel-Abbes (West Algeria).

Material and methods: The protocol was carried out on a cohort of 125 school children aged of 5 to 11 years, including 64 boys and 61 girls, and 139 school children, including 93 boys and 46 girls in Ain Defla and Sidi-Bel-Abbes respectively. Concerning the classification of obesity and overweight, we referred to the International Obesity Task Force and the French References' curves.

Results: Regarding dietary intake our results showed that 34% of students from both regions took their breakfast, compared to 66% who did not take. Furthermore, 73% of students skipped at least one meal, however 23% respected meals frequency i.e. 4 meals a day. Regarding socio-economic factors and physical activity, our findings showed that obesity rates were high (36%) among children whose fathers are workers. However, for mothers who are housewives, obesity increases among their children (88%). The relationship was reversed between the parents' education level and the Body Mass Index. We found an opposite relationship between Body Mass Index and physical activity, and investigated children use screen devices for long time periods.

Conclusions: Our study showed a positive relationship between obesity and overweight and environmental factors.

Genetic and environmental (physical fitness and sedentary activity) interaction effects on cardiometabolic risk factors in Mexican American children and adolescents

Knowledge on genetic and environmental (G × E) interaction effects on cardiometabolic risk factors (CMRFs) in children is limited.  The purpose of this study was to examine the impact of G × E interaction effects on CMRFs in Mexican American (MA) children (n = 617, ages 6-17 years). The environments examined were sedentary activity (SA), assessed by recalls from "yesterday" (SAy) and "usually" (SAu) and physical fitness (PF) assessed by Harvard PF scores (HPFS). CMRF data included body mass index (BMI), waist circumference (WC), fat mass (FM), fasting insulin (FI), homeostasis model of assessment-insulin resistance (HOMA-IR), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), systolic (SBP) and diastolic (DBP) blood pressure, and number of metabolic syndrome components (MSC). We examined potential G × E interaction in the phenotypic expression of CMRFs using variance component models and likelihood-based statistical inference. Significant G × SA interactions were identified for six CMRFs: BMI, WC, FI, HOMA-IR, MSC, and HDL, and significant G × HPFS interactions were observed for four CMRFs: BMI, WC, FM, and HOMA-IR. However, after correcting for multiple hypothesis testing, only WC × SAy, FM × SAy, and FI × SAu interactions became marginally significant. After correcting for multiple testing, most of CMRFs exhibited significant G × E interactions (Reduced G × E model vs. Constrained model). These findings provide evidence that genetic factors interact with SA and PF to influence variation in CMRFs, and underscore the need for better understanding of these relationships to develop strategies and interventions to effectively reduce or prevent cardiometabolic risk in children.

Salivary adiponectin concentration in healthy adult males in relation to anthropometric measures and fat distribution

Objectives. Body fat content, fat distribution, and adiponectin level are important variables in the development of obesity related complications. Anthropometric indices may provide an economic and faster method in measuring the risk for complications through their predictive effect of fat distribution and adiponectin concentration. We aimed to determine, which of the waist circumference (WC), waist-to-hip ratio (WHR), and body mass index (BMI) may be the best predictor for the total fat percentage (WF), visceral fat level (VF), and subcutaneous whole-body fat (SCWBF). We aimed also to investigate the potential use of the anthropometric measures and fat distribution as predictors for the salivary adiponectin level in the healthy adult males. Subjects. A total of 88 adult males aged between 18−25 years with a wide range of BMI were studied. Anthropometric indices were measured using standardized methods and salivary adiponectin level was assessed using an enzyme-linked immunosorbent assay. Results. In path analysis of the Structural Equation Model (SEM) using IBM@SPSS AMOS, version22, BMI and WC, but not WHR, were strong predictors for WF and SCWBF (p<0.05). BMI but not WC was a strong predictor for VF (p<0.001). WF was strong predictor for SCWBF (p<0.001), but not for VF. BMI, WC, WHR, WF, VF, and SCWBF were poor predictors of the salivary adiponectin level. Conclusion. BMI is the best predictor for the total body fat and fat distribution. However, WHR seems to be of a little value and the salivary adiponectin level independent of BMI and body fat in healthy adult Malay males.

Association between adiposity indicators, metabolic parameters and inflammatory markers in a sample of female adolescents

OBJECTIVE

The aim of this study was to investigate the association between total and abdominal adiposity with metabolic parameters and inflammatory markers, in female adolescents.

SUBJECTS AND METHODS

The sample consisted of 53 adolescents aged 13 to 17 years from a public school in Curitiba, Brazil. The adiposity indicators studied were body mass index (BMI), waist circumference (WC), trunk fat mass (TKFM), total fat mass (TFM) and body fat percentage (BF%) measured by dual-energy X-ray absorptiometry. The metabolic and inflammatory parameters studied were systolic blood pressure (SBP), diastolic blood pressure (DBP), glucose, insulin, homeostasis model assessment index for insulin resistance (HOMA-IR), lipids, C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), leptin, adiponectin and resistin.

RESULTS

Eighty percent of WC variation, 87% of TKFM and TFM, and 73% of BF% were predicted by BMI variation. There was a significant positive correlation between all indicators of adiposity with SBP, DBP, insulin, HOMA-IR, CRP and leptin. Triglycerides were positively correlated with BMI and WC, and adiponectin correlated negatively with BMI. TNF-α, IL-6, glucose, total cholesterol, and high- and low-density lipoprotein cholesterol did not correlate to the studied variables.

CONCLUSION

BMI showed a significant association with most of the parameters studied, and WC was slightly better than BMI to predict insulin resistance in this specific population.

Associations between accelerometer-measured physical activity and body fatness in school-aged children

Background

The main aim of the study was to examine the cross-sectional associations between objectively measured physical activity (PA) and body fatness in 7–12-year-old children.

Methods

We performed an analysis of 365 children (209 girls). Participant recruitment was performed in eight randomly selected elementary schools in cities and towns with various numbers of inhabitants. The body composition analysis was performed according to a multi-frequency bioelectrical impedance analysis; PA was monitored using an accelerometer.

Results

In terms of the overall PA, boys were more active than girls. No significant associations (unadjusted and adjusted models) were found between light PA and all body fatness indicators in either sex. Moderate-to-vigorous PA was significantly negatively associated with all body fatness indicators only in girls. These associations strengthened after adjustment for age, height and sedentary time (β ranging from –0.49 to –0.36, P ≤ 0.01). In contrast, vigorous PA was strongly negatively associated with body fatness indicators only in boys. In the fully adjusted model the significant negative associations were found for fat mass percentage (β = –0.15, P = 0.048) and fat mass index (β = –0.15, P = 0.040).

Conclusions

The present study suggests that increasing sex-specific PA of different intensities may be an appropriate approach for decreasing body fatness in children. Longitudinal studies are needed to verify these associations.

Perinatal, sociodemographic and lifestyle correlates of increased total and visceral fat mass levels in schoolchildren in Greece: the Healthy Growth Study

Objective

To identify possibly independent associations of perinatal, sociodemographic and lifestyle factors with childhood total and visceral body fat.

Design

A representative sample of 2655 schoolchildren (9–13 years) participated in the Healthy Growth Study, a cross-sectional epidemiological study.

Setting

Seventy-seven primary schools in four large regions in Greece.

Subjects

A sample of 1228 children having full data on total and visceral fat mass levels, as well as on anthropometric, dietary, physical activity, physical examination, socio-economic and perinatal indices, was examined.

Results

Maternal (OR=3·03 and 1·77) and paternal obesity (OR=1·62 and 1·78), maternal smoking during pregnancy (OR=1·72 and 1·93) and rapid infant weight gain (OR=1·42 and 1·96) were significantly and positively associated with children’s increased total and visceral fat mass levels, respectively. Children’s television watching for >2 h/d (OR=1·40) and maternal pre-pregnancy obesity (OR=2·46) were associated with children’s increased total and visceral fat mass level, respectively. Furthermore, increased children’s physical activity (OR=0·66 and 0·47) were significantly and negatively associated with children’s total and visceral fat mass levels, respectively. Lastly, both father’s age >46 years (OR=0·57) and higher maternal educational level (OR=0·45) were associated with children’s increased total visceral fat mass level.

Conclusions

Parental sociodemographic characteristics, perinatal indices and pre-adolescent lifestyle behaviours were associated with children’s abnormal levels of total and visceral fat mass. Any future programme for childhood prevention either from the perinatal age or at late childhood should take these indices into consideration.

Association of Habitual Patterns and Types of Physical Activity and Inactivity with MRI-Determined Total Volumes of Visceral and Subcutaneous Abdominal Adipose Tissue in a General White Population

Population-based evidence for the role of habitual physical activity (PA) in the accumulation of visceral (VAT) and subcutaneous (SAAT) abdominal adipose tissue is limited. We investigated if usual patterns and types of self-reported PA and inactivity were associated with VAT and SAAT in a general white population. Total volumes of VAT and SAAT were quantified by magnetic resonance imaging in 583 men and women (61 ± 11.9 y; BMI 27.2 ± 4.4 kg/m2). Past-year PA and inactivity were self-reported by questionnaire. Exploratory activity patterns (APAT) were derived by principal components analysis. Cross-sectional associations between individual activities, total PA in terms of metabolic equivalents (PA MET), or overall APAT and either VAT or SAAT were analyzed by multivariable-adjusted robust or generalized linear regression models. Whereas vigorous-intensity PA (VPA) was negatively associated with both VAT and SAAT, associations between total PA MET, moderate-intensity PA (MPA), or inactivity and VAT and/or SAAT depended on sex. There was also evidence of a threshold effect in some of these relationships. Total PA MET was more strongly associated with VAT in men (B = -3.3 ± 1.4; P = 0.02) than women (B = -2.1 ± 1.1; P = 0.07), but was more strongly associated with SAAT in women (B = -5.7 ± 2.5; P = 0.05) than men (B = -1.7 ± 1.6; P = 0.3). Men (-1.52 dm3 or -1.89 dm3) and women (-1.15 dm3 or -2.61 dm3) in the highest (>6.8 h/wk VPA) or second (4.0-6.8 h/wk VPA) tertile of an APAT rich in VPA, had lower VAT and SAAT, respectively, than those in the lowest (<4.0 h/wk VPA) tertile (P ≤ 0.016; P trend ≤ 0.0005). They also had lower VAT and SAAT than those with APAT rich in MPA and/or inactivity only. In conclusion, our results suggest that in white populations, habitual APAT rich in MPA might be insufficient to impact on accumulation of VAT or SAAT. APAT including ≥ 4.0-6.8 h/wk VPA, by contrast, are more strongly associated with lower VAT and SAAT.

Adolescent and young adult female determinants of visceral adipose tissue at ages 26-28 years

OBJECTIVE

To assess adolescent and young adult determinants of visceral adipose tissue (VAT) at ages 26-28 years.

STUDY DESIGN

Prospective study (ages 9-28 years) of cardiometabolic measures, menarche age, menses irregularities, metabolic syndrome, impaired fasting glucose-type 2 diabetes mellitus, and VAT in 400 girls (248 black, 152 white).

RESULTS

Adolescent (age 14-19) independent variables for greater VAT at ages 26-28 included larger mean waist circumference (partial R(2) = 30.8%), earlier age at menarche (0.9%), and white race (1.8%). Young adult (ages 20-28 years) independent variables for greater VAT included larger mean waist circumference (partial R(2) = 61.7%), greater triglyceride levels (3.3%), lower high-density lipoprotein cholesterol (1.0%), and greater insulin resistance (homeostasis model assessment-estimated insulin resistance; 0.4%). Independent variables for greater VAT when both adolescent and young adult variables were used included waist (tertile rank change from adolescence to young adulthood, partial R(2) = 58.3%), greater young adult triglyceride levels (4.4%), white race (1.8%), greater young adult homeostasis model assessment-estimated insulin resistance (age 20-28, 2.4%), and earlier menarche age (0.7%). Menses irregularities were not independently associated with young adult VAT.

CONCLUSIONS

Adolescent girls with early menarche and larger waist circumference should be targets for primary prevention of accretion of VAT. In young adulthood, VAT is associated with dysregulated cardiometabolic profiles, which is greater for those with waist circumference increases from adolescence to adulthood. Waist circumference during young adulthood, and to a lesser degree during adolescence, is an inexpensive surrogate for VAT at ages 26-28 years.

The impact of low subcutaneous fat in patients with nontuberculous mycobacterial lung disease

BACKGROUND

Nontuberculous mycobacteria (NTM) are pathogens that cause chronic respiratory disease, even in immunocompetent patients. We hypothesized that low subcutaneous fat is a predisposing factor for NTM lung disease.

METHODS

Following a retrospective review of medical records from between 2005 and 2012, a total of 148 patients with NTM lung disease and 142 age- and sex-matched controls were enrolled. We evaluated subcutaneous fat using chest computed tomography (CT) scans at the midpole level of the left kidney.

RESULTS

The median age of the patients was 62 years and 60.8 % were female. Approximately 71 % were classified into a nodular bronchiectatic group. The patient group had significantly less subcutaneous fat than the control group (39.3 vs. 53.0 cm(2), p = 0.001). Patients with both localized disease (43.5 vs. 53.0 cm(2), p = 0.042) and extensive disease (35.9 vs. 53.0 cm(2), p < 0.0001) had less subcutaneous fat compared with the control group. No difference in subcutaneous fat was observed with respect to the increasing bacterial load in sputum (p = 0.246). In 20 patients with prominent disease progression during the follow-up period, no significant difference was observed between subcutaneous fat at the initial diagnosis and that at the follow-up CT (36.2 vs. 42.0 cm(2), p = 0.47).

CONCLUSION

Our results suggest that lower subcutaneous fat may contribute to host susceptibility to NTM lung disease.

Healthy behaviours and abdominal adiposity in adolescents from southern Italy

OBJECTIVE

The present study aimed to evaluate the prevalence of meeting health recommendations on diet and physical activity (having breakfast, eating fruit and vegetables, consumption of milk/yoghurt, performing moderate-to-vigorous physical activity, limiting television watching) and to assess junk snack food consumption in adolescents from southern Italy. The association between healthy behaviours and abdominal adiposity was also examined.

DESIGN

In a cross-sectional protocol, anthropometric data were measured by trained operators while other data were collected through a structured interview.

SETTING

Three high schools in Naples, Italy.

SUBJECTS

A sample of 478 students, aged 14-17 years, was studied.

RESULTS

The proportion of adolescents who met each of the health recommendations varied: 55·4% had breakfast on ≥6 d/week; 2·9% ate ≥5 servings of fruit and vegetables/d; 1·9% had ≥3 servings of milk/yoghurt daily; 13·6% performed moderate-to-vigorous physical activity for ≥60 min/d; and 46·3% watched television for <2 h/d. More than 65% of adolescents consumed ≥1 serving of junk snack foods/d. Only 5% fulfilled at least three recommendations. Healthy habits tended to correlate with each other. As the number of health recommendations met decreased, the percentage of adolescents with high abdominal adiposity (waist-to-height ratio ≥0·5) increased. The trend was not significant when the proportion of overweight/obese adolescents was considered. Logistic regression analysis indicated that male gender and watching television for ≥2 h/d were independently associated with a higher waist-to-height ratio.

CONCLUSIONS

Most adolescents failed to meet the five health recommendations considered. Male gender and excessive television watching were associated with abdominal adiposity.

Relationships between direct and indirect measures of central and total adiposity in children: what are we measuring?

OBJECTIVE

The relationship between central and total fat measured by anthropometry, dual energy X-ray absorptiometry, and magnetic resonance imaging (MRI) with each other and systolic blood pressure (SBP) was examined.

DESIGN AND METHODS

Participants of the Avon Longitudinal Study of Parents and Children were examined at ages 9, 11, 13, and 15 years (n = 3,796-6,567). MRI was available on a subset of children at 11 (n = 156) and 13 (n = 95).

RESULTS

Body mass index (BMI) and waist circumference (WC) were highly correlated (r = 0.84-0.91, across ages), and total body fat mass (TBFM) and trunk fat mass (TFM) were very strongly correlated (r ≥ 0.98). Among boys, BMI vs. WC explained a similar degree of variation in TBFM and TFM (41-71% vs. 43-76%, across age and overweight groups); in girls, BMI accounted for 62-73% variance and WC 47-69%. Adiposity measures were generally similarly correlated with SBP within age groups. Further, the relationship between intra-abdominal adipose tissue (IAAT) volume and adiposity measures did not vary greatly at 11 (0.65-0.67) and 13 (0.64-0.67).

CONCLUSIONS

BMI and WC contain a large amount of overlapping information as evidenced by their high correlation and similarly sized associations with fat mass, SBP, and IAAT. This suggests that WC may be an inadequate marker of central adiposity during childhood.

Sleep and birthweight predict visceral adiposity in overweight/obese children

BACKGROUND

Visceral adiposity poses significant consequences for long-term health and it is important to identify methods that can be used to prevent fat deposition in visceral adipose tissue.

OBJECTIVE

To identify the factors contributing to differential fat distribution in overweight/obese children.

METHODS

Demographic, dietary and lifestyle factors potentially associated with increased visceral adipose tissue in overweight and obese South-Indian children aged 3 to 16 years. The diagnosis of visceral obesity was based on the waist-to-height ratio (WHtR) cut-off value of 0.5.

RESULTS

Exposure variables with statistically different distributions in the two WHtR categories, when examined by Mann-Whitney and chi-square tests, were used to develop a binary logistic regression model of visceral adiposity. Increased birthweight and higher sleep duration were significant predictors of having a healthy WHtR, with odds ratios of 1.30 and 1.26 respectively.

CONCLUSIONS

Early programming effects associated with low birthweight and current sleep deprivation could promote the storage of excess fat as visceral adipose tissue in overweight and obese children.

Trends in general and abdominal obesity among Chinese children and adolescents 1993-2009

OBJECTIVE

This study aimed to examine the secular trends in body mass index (BMI) and waist circumference (WC), and the prevalence of general and abdominal obesity among Chinese children and adolescents from 1993 to 2009.

METHODS

Data were obtained from the China health and nutrition survey conducted from 1993 to 2009. 9693 children and adolescents aged 6-17 years were included in this study, with their height, weight and WC measured. General obesity was defined using the BMI cut-offs for overweight recommended by the International Obesity Task Force, and abdominal obesity was assessed when a WC is above the 90th percentile for gender and age.

RESULTS

Among the total participants, mean BMI and WC increased significantly over the period 1993-2009: BMI increased from 17.6 to 17.8 kg m(-2) , and WC increased from 61.4 to 63.1 cm (both increases P < 0.001). The prevalence of general obesity and abdominal obesity increased significantly over the period: general obesity (including overweight) rose from 6.1% to 13.1% and abdominal obesity from 4.9% to 11.7% (both increases P < 0.001). WC and abdominal obesity increased at a relatively higher rate than BMI and general obesity. Upward trends in the prevalence of general and abdominal obesity were observed in all subgroups of gender, age and region (all increases P < 0.05), except for abdominal obesity in girls aged 13-17 years (P = 0.102).

CONCLUSION

General and abdominal obesity increased significantly over the past 17 years in Chinese children.

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.

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.

[Physical activity and obesity]

One reason for the high prevalence of overweight and obesity might be the differences in lifestyle compared to earlier decades, called the "obesogenic environment." With this, the decline in physical activity (PA) in favor of a sedentary lifestyle is assumed to play an important role. Physical activity or inactivity has a major impact on the development of overweight and obesity as well as on certain metabolic disorders. This review summarizes current scientific knowledge regarding the association between PA and overweight/obesity. The term "physical activity" is defined and different methods of its assessment are introduced. In addition, certain methods for the evaluation/operationalization of collected PA data are described. Finally, some epidemiological studies dealing with the associations between PA and overweight/obesity in children/adolescents as well as in adults are presented.

Spontaneous physical activity protects against fat mass gain

OBJECTIVE

It is unclear whether elevated spontaneous physical activity (SPA, very low-intensity physical activity) positively influences body composition long term. We determined whether SPA and caloric intake were differentially related to the growth curve trajectories of body weight, fat mass (FM) and fat-free mass (FFM) between obesity resistant and Sprague-Dawley rats at specific age intervals.

DESIGN AND SUBJECTS

Body composition, SPA and caloric intake were measured in selectively-bred obesity-resistant and out-bred Sprague-Dawley rats from 1 to 18 months. Data from development throughout maturation were analyzed by longitudinal growth curve modeling to determine the rate and acceleration of body weight, FM- and FFM-gain.

RESULTS

Obesity-resistant rats had a lower rate of FM gain overall, a lower acceleration in body weight early in life, significantly greater SPA and lower cumulative caloric intake. Greater SPA in obesity-resistant rats was significantly associated with a lower rate of FM gain overall and lower acceleration in body weight early in life. Obesity resistant rats lost less FFM compared with Sprague-Dawley rats despite that obesity-resistant rats had a lower acceleration in FFM gain early in life. Obesity-resistant rats gained less FM and more FFM per gram body weight and were less energy efficient than Sprague-Dawley rats. Caloric intake was significantly and positively related to body weight, FM and FFM gain in both groups. Circadian patterns of caloric intake were group and age-dependent. Our data demonstrate that elevated and sustained SPA during development and over the lifespan are related to the reduced the rate of FM gain and may preserve FFM.

CONCLUSION

These data support the idea that SPA level is a reproducible marker that reliably predicts propensity for obesity in rats, and that elevated levels of SPA maintained during the lifespan promote a lean phenotype.

Time spent in sedentary behavior and changes in childhood BMI: a longitudinal study from ages 9 to 15 years

OBJECTIVE

To determine if time spent in objectively measured sedentary behavior is associated with a change in body mass index (BMI) between ages 9 and 15 years, adjusting for moderate-to-vigorous physical activity (MVPA).

DESIGN

Prospective observational study of children at ages 9 (2000), 11 (2002), 12 (2003) and 15 years (2006). Longitudinal quantile regression was used to model the influence of predictors on changes at the 10th, 25th, 50th, 75th and 90th BMI percentiles over time.

SUBJECTS

Participants were enrolled in the National Institute of Child Health and Human Development (NICHD) Study of Early Child Care and Youth Development and include both boys and girls (n=789).

MEASUREMENTS

Objectively measured BMI (kg m(-2)) was the outcome variable and objectively measured sedentary behavior was the main predictor. Adjustment was also made for MVPA, gender, race, maternal education, hours of sleep and healthy eating index.

RESULTS

Increases in BMI were observed at all percentiles, with the greatest increase observed at the 90th BMI percentile. Spending more time in sedentary behavior (h per day) was associated with additional increases in BMI at the 90th, 75th and 50th BMI percentiles, independent of MVPA and the other covariates (90th percentile=0.59, 95% confidence interval (95% CI): 0.19-0.98 kg m(-2); 75th percentile=0.48, 95% CI: 0.25-0.72 kg m(-2); and 50th percentile=0.19, 95% CI: 0.05-0.33 kg m(-2)). No associations were observed between sedentary behavior and changes at the 25th and 10th BMI percentiles.

CONCLUSION

Sedentary behavior was associated with greater increases in BMI at the 90th, 75th and 50th BMI percentiles between ages 9 and 15 years, independent of MVPA. Preventing an increase in sedentary behavior from childhood to adolescence may contribute to reducing the number of children classified as obese.

Is adipose tissue metabolically different at different sites?

This review focuses on metabolic differences of adipose tissue at different sites of the body, with emphasis in pediatrics. Adipose tissue is composed of various cell types, which include adipocytes and other cells of the stromal vascular fraction such as preadipocytes, blood cells, endothelial cells and macrophages. Mammals have two main types of adipose tissue: white adipose tissue (WAT), and brown adipose tissue (BAT), each of which possesses unique cell autonomous properties. WAT and BAT differ at the functional, as well as the morphological and molecular levels. WAT accumulates surplus energy mainly in the form of triacylglycerols and BAT dissipates energy directly as heat. Recently, functional BAT in humans has been located in the neck, supraclavicular, mediastinal and interscapular areas. WAT is distributed throughout the body in the form of two major types: subcutaneous adipose tissue (SWAT) and the intra-abdominal visceral adipose tissue (VWAT). VWAT tissue is associated with insulin resistance, diabetes mellitus, dyslipidaemia, hypertension, atherosclerosis, hepatic steatosis, and overall mortality whereas SWAT and BAT have intrinsic beneficial metabolic properties. Subcutaneous and visceral adipocytes derive from different progenitor cells that exhibit a different gene expression pattern. SWAT responds better to the antilipolytic effects of insulin and other hormones, secrets more adiponectin and less inflammatory cytokines, and is differentially affected by molecules involved in signal transduction as well as drugs compared with VWAT. Current research is investigating various approaches of BAT and SWAT transplantation, including new sources of adipocyte progenitors. This may be important for the potential treatment of childhood obesity.

Efficacy of increasing physical activity to reduce children's visceral fat: a pilot randomized controlled trial

OBJECTIVE

To examine whether differentially targeting physical activity within the context of pilot family-based pediatric weight control treatment results in differential change in abdominal fat, particularly visceral fat.

METHOD

Twenty-nine overweight children (>85(th) body mass index [BMI] percentile) and at least one participating parent were randomly assigned to one of two family-based behavioral weight management conditions that either targeted 1) primarily dietary change (STANDARD; n = 15) or 2) dietary plus physical activity change (ADDED; n = 14). Differences at post-treatment in overall child weight status (e.g., BMI), whole-body composition (measured by dual x-ray absorptiometry), and abdominal fat (measured by waist circumference and magnetic resonance imaging) were assessed using intent-to-treat analyses, as were post-treatment parent BMI and waist circumference. Child and parent physical activity and dietary behavior changes were also evaluated. Results. At post-treatment, overall child weight status, whole-body composition, and child dietary measures did not differ by condition. Children in the ADDED condition tended to have higher physical activity and lower visceral abdominal fat at post-treatment relative to children in the STANDARD condition.

CONCLUSIONS

Increasing physical activity may be important to optimize reductions in abdominal fat, especially visceral fat, among overweight children provided with family-based behavioral weight management treatment.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00359957.

[Cost-effectiveness of an intervention to reduce overweight and obesity in 9-10-year-olds. The Cuenca study]

OBJECTIVE

To assess the cost-effectiveness a school-based intervention designed to reduce overweight/obesity and other cardiovascular risk factors in children.

METHODS

Standard cost effectiveness analysis methods and two perspectives (societal and institutional) were used. A cluster-randomized controlled trial with 10 intervention schools (691 children) and 10 control schools (718 children) was performed. Net costs were calculated by subtracting the usual after-school care cost from intervention costs. The effectiveness of the intervention was measured as the reduction in health outcomes compared with the control group.

RESULTS

The intervention costs totaled 125,469.75€, representing 269.83 €/year/child. The usual after-school care was estimated at 844,56 €/year/child. Intervention children showed a decrease in triceps skinfold thickness (-1.25mm, 95% CI: -1.82 to -0.67; P<.001). Intervention children with body mass index (BMI) between the percentiles 25 and 75 showed a decrease in the percentage of body fat (-0.59%; 95% CI: -1.03 to -0.67; P<.001), and those with a BMI>P75 showed a decrease in triceps skinfold thickness (-1.87mm; 95%CI: -3.43 to -0.32; P<.001), and percentage of body fat (-0.67%; 95%CI: -1.32 to -0.01; P<.05).

CONCLUSIONS

This type of after-school program for recreational physical activity to prevent obesity are likely to be a cost-effective use of public funds and warrant careful consideration by policy makers and program planners.

Associations between moderate-to-vigorous physical activity and central body fat in 3-8-year-old children

The aim of this study was to examine the associations between objectively measured moderate-to-vigorous physical activity (MVPA) and central body fat (CBF) indicators by anthropometry and dual energy X-ray absorptiometry (DXA) in young children. This study comprised 110 children aged 3-8 years. The associations between MVPA and CBF measures by anthropometry (waist circumference, waist-to-height ratio, skinfold thicknesses [subscapular, suprailiac, trunk-to-extremity and trunk-to-total skinfold ratios] and total trunk-to-waist circumference), DXA (trunk fat) and a combination of both (total trunk skinfolds-to-trunk fat by DXA) were examined by linear regression. Levels of MVPA showed a significant inverse association with 8 of 9 indicators of CBF after controlling for age, gender and height, and fat-free mass. When total fat mass measured by DXA was included into the model, levels of MVPA remained significantly associated with 6 of 9 indicators of CBF. The results highlight the plausible role of MVPA on CBF in young children but longitudinal studies are necessary.

Active commuting to school in children and adolescents: an opportunity to increase physical activity and fitness

AIMS

The purpose was to describe the patterns of commuting to school in young people and to examine its associations with physical activity (PA) and cardiorespiratory fitness.

METHODS

The sample comprised 2271 Estonian and Swedish children and adolescents (1218 females) aged 9-10 years and 15-16 years. Data were collected in 1998/99. Mode of commuting to and from school was assessed by questionnaire. Time spent (min/day) in PA and average PA (counts/min) was measured by accelerometry. Cardiorespiratory fitness was assessed by means of a maximal cycle ergometer test.

RESULTS

Sixty-one percent of the participants reported active commuting to school (ACS). Estonian youth showed lower levels of ACS than Swedish (odds ratio, 0.64; 95% confidence interval, 0.53-0.76) and girls reported lower levels than boys (0.74; 0.62-0.88). ACS boys showed higher PA levels than non-ACS boys for moderate, vigorous, MVPA, and average PA levels (all p ≤ 0.01). Participants who cycled to school had higher cardiorespiratory fitness than walkers or passive travellers (p < 0.001).

CONCLUSIONS

Nearly two-thirds of the participants actively commuted to school. ACS may provide an opportunity to increase levels of daily PA, especially in boys, and cardiorespiratory fitness, especially if cycling. Public health strategies should develop and test ACS patterns to get more evidence and promote bike-friendly environments.

Visceral adipose tissue in children and adolescents: a review

Research conducted among adults has mainly shown that visceral adipose tissue (VAT) is strongly linked to insulin resistance, type 2 diabetes, hypertension and dyslipidaemia, leading to increased risk of CVD or the metabolic syndrome. However, little is known about the aetiology, determinants and consequences of VAT in children. The present article reviews the current literature relating to the factors influencing visceral fat accumulation in children and adolescents. The literature used in the present study was collected by searching a PubMed database, in which studies up to 2008 exploring the factors influencing accumulation of visceral fat among children and youth were found on the basis of appropriate keywords. Further studies concerning different factors influencing deposition of VAT among children and youth should first of all concentrate on: carrying out long-term analyses among children of different ethnical groups, which should begin in the period of prepuberty and which should cover the whole period of puberty till adulthood; drawing up norms specifying the amount of VAT among healthy children; identification of anthropometric indicators which will help to determine the VAT:subcutaneous adipose tissue ratio in the most precise way; broader studies of the influence of eating habits on developing VAT deposit among children and youth.

Increased physical activity and reduced adiposity in overweight Hispanic adolescents

PURPOSE

The objectives of this study were to examine 1) whether changes in total physical activity (PA; counts per minute, cpm) and time spent in moderate to vigorous PA (MVPA) are associated with changes in adiposity and 2) whether energy intake influences the relationship between changes in PA and changes in adiposity in overweight Hispanic adolescents.

METHODS

Analysis included 38 overweight (body mass index, >85th percentile) Hispanic adolescents with complete pretest and posttest data on relevant variables after participating in a 16-wk intervention. The intervention treatment did not influence PA, so the sample was combined and the randomization group was adjusted for in the analysis. Body composition by dual-energy x-ray absorptiometry, 7-d PA by accelerometry, and dietary intake by 3-d diet records were assessed before and after intervention.

RESULTS

Within individuals, the mean increase of PA (n = 19) and mean decrease of PA (n = 19) was approximately 105 cpm. A 100-cpm increase in total PA was associated with a decrease of 1.3 kg of fat mass and 0.8% body fat after adjusting for pretest adiposity, PA, age, sex, and treatment (P < 0.05). Controlling for energy intake modestly strengthened the relationships between total PA and fat mass and percent body fat. Changes in MVPA were not related to changes in adiposity after controlling for total PA (P > 0.05).

CONCLUSIONS

Increasing total PA by 28% (100 cpm) was associated with a decrease of 1.4 kg of fat mass and 1% body fat for 16 wk in overweight Hispanic adolescents independent of intervention group assignment. Increases in total PA, compared with MVPA, may be sufficient to improve body composition in overweight Hispanic adolescents.

Developing waist-to-height ratio cut-offs to define overweight and obesity in children and adolescents

OBJECTIVE

The waist-to-height ratio (WHtR) assesses abdominal adiposity and has been proposed to be of greater value in predicting obesity-related cardiovascular health risks in children than BMI. The present study aims to develop WHtR cut-offs for overweight and obesity based on the 85th and 95th percentiles for the percentage body fat (%BF) in a cohort of children and adolescents.

DESIGN

Waist circumference (WC), height, triceps and subscapular skinfolds were used to calculate WHtR and %BF. Correlations between WHtR and %BF and WHtR/mid-abdominal skinfold were made. Receiver-operating characteristic (ROC) curve analysis was used to select WHtR cut-offs to define overweight and obesity. Subjects were grouped by WHtR cut-offs, and mean values for anthropometry, blood lipids and blood pressure (BP) variables were compared.

SETTING

Australian primary and secondary schools.

SUBJECTS

A total of 2773 male (M) and female (F) subjects of the 1985 Australian Health and Fitness Survey, aged 8-16 years.

RESULTS

Correlation coefficients between WHtR and %BF were M: r = 0.73, F: r = 0.60, P < 0.01 and WHtR/mid-abdominal skinfold were M: r = 0.78, F: r = 0.65, P < 0.01. WHtR of 0.46(M) and 0.45(F) best identified subjects with > or = 85th percentile for %BF and 0.48(M) and 0.47(F) identified subjects with > or = 95th percentile for %BF. When comparing the highest WHtR group to the lowest, both sexes had significantly higher means for weight, WC, %BF, TG (male subjects only), systolic BP (female subjects only) and lower means for HDL cholesterol (P < 0.05).

CONCLUSIONS

WHtR is useful in clinical and population health as it identifies children with higher %BF at greater risk of developing weight-related CVD at an earlier age.

Physical activity and abdominal obesity in youth

Childhood obesity continues to escalate despite considerable efforts to reverse the current trends. Childhood obesity is a leading public health concern because overweight–obese youth suffer from comorbidities such as type 2 diabetes mellitus, nonalcoholic fatty liver disease, metabolic syndrome, and cardiovascular disease, conditions once considered limited to adults. This increasing prevalence of chronic health conditions in youth closely parallels the dramatic increase in obesity, in particular abdominal adiposity, in youth. Although mounting evidence in adults demonstrates the benefits of regular physical activity as a treatment strategy for abdominal obesity, the independent role of regular physical activity alone (e.g., without calorie restriction) on abdominal obesity, and in particular visceral fat, is largely unclear in youth. There is some evidence to suggest that, independent of sedentary activity levels (e.g., television watching or playing video games), engaging in higher-intensity physical activity is associated with a lower waist circumference and less visceral fat. Several randomized controlled studies have shown that aerobic types of exercise are protective against age-related increases in visceral adiposity in growing children and adolescents. However, evidence regarding the effect of resistance training alone as a strategy for the treatment of abdominal obesity is lacking and warrants further investigation.

Objectively measured physical activity, physical activity related personality and body mass index in 6- to 10-yr-old children: a cross-sectional study

Background

The prevalence and level of overweight in childhood is rapidly increasing. One potential contributor to the rise in overweight is a decline in physical activity (PA). The purpose of this study was to compare levels and patterns of PA and PA related personality in normal-weight (NW) and overweight (OW) 6- to 10-yr-old children.

Methods

Subjects were grouped into OW (N = 59, BMI = 24.2 ± 4.8 kg/m²) or NW (N = 61, BMI = 15.7 ± 1.5 kg/m²) according to International Obesity Task Force cut-offs. PA was assessed by accelerometry. Parents filled in a questionnaire on PA and sedentary behaviour and PA related personality of their child (born tired, moves slowly, is often tired, lacks energy, avoids physical efforts, prefers watching playing children instead of joining them, is always active, needs to let himself/herself go, has a lot of energy).

Results

NW children spent on average 77 min/day in MVPA, whereas OW children only 57 min/day (p = .001). OW children had fewer 5, 10 and 20 min bouts of MVPA (p = .01). OW and NW children showed identical PA patterns on both week days and weekends, although at different levels. According to parents' report, a greater percentage of OW children was not engaged in any sport (46% versus 23%, chi² = 6.3, p = .01). OW children had a less active personality (p < .001), watched more TV during weekend (p < .01), but no differences were found in outside play or non-active play. BMI of mother and father explained 29% of the variance in children's BMI z-score (p < .001). PA related personality, screen behaviour during weekend and MVPA explained an additional 12% (p < 0.01).

Conclusion

The results of this study demonstrate that NW children spent on average 20 min per day more in MVPA. PA patterns were similar in NW versus OW children, although at different levels. Greatest differences in PA according to weight status were found in the afternoon during after school hours. This is the first study to show distinct PA related personality traits in OW children compared to NW peers.

Early development of visceral fat excess after spontaneous catch-up growth in children with low birth weight

CONTEXT

The sequence of prenatal growth restraint and infantile catch-up of weight is by the age of 4 yr associated with hyperinsulinemic adiposity. We studied whether the adiposity of post-catch-up children born small for gestational age (SGA) is further amplified between age 4 and 6 yr and whether visceral fat excess has already emerged by the age of 6 yr.

SETTING

The study took place at a university hospital.

STUDY POPULATION AND DESIGN

A longitudinal cohort (age 2-6 yr) of 22 children born appropriate for gestational age (AGA) and 29 born SGA were studied. Auxological, endocrine, metabolic, and body composition (by absorptiometry) assessments were made at 2, 4, and 6 yr, and visceral fat was assessed (by magnetic resonance imaging) at 6 yr.

MAIN OUTCOMES

Outcome measures included fasting glucose, insulin, IGF-I, neutrophil to lymphocyte ratio, lean mass, and total, abdominal, and visceral fat mass.

RESULTS

Between ages 4-6 yr, the relative adiposity of SGA children was further amplified. Between ages 2-6 yr, SGA children gained more total and abdominal fat and raised their insulin, IGF-I, and neutrophil to lymphocyte ratio more than did AGA children (all P<0.0001). At age 6 yr, the average amount of visceral fat was in SGA children more than 50% higher than in AGA children (P<0.005). The 0- to 2-yr increment in weight Z-score together with the 2- to 6-yr increment in fasting insulin accounted for 62% of visceral fat variability at age 6 yr.

CONCLUSION

The amount of visceral fat is in post-catch-up SGA children excessive by the age of 6 yr. In populations at risk for type 2 diabetes or metabolic syndrome after fetal growth restraint, the time window for early intervention may have to be advanced into prepubertal childhood.

Behavioral risk factors in relation to visceral adipose tissue deposition in adolescent females

OBJECTIVE

To characterize visceral adipose tissue (VAT) and subcutaneous abdominal adipose tissue (SAAT) deposition in girls over the pubertal period and to assess the influence of behavioral risk factors on their deposition.

PARTICIPANTS

In total, 41 subjects of mean age of 13.5 years (standard deviation, SD=0.9) were assessed at menarche. At 4 years after menarche, follow-up data were available for 24 of these subjects.

METHODS

VAT and SAAT were measured by magnetic resonance imaging (MRI) and total body fat by isotopic dilution of (18)O water at menarche and 4 years after menarche in a subset of subjects enrolled in a larger study of growth and development. Smoking, alcohol use, and physical activity were assessed by self-report at both time points. Smoking, alcohol use, and physical activity at 4 years after menarche were assessed in relation to concurrent VAT and SAAT, and to the 4-year change in VAT and SAAT.

RESULTS

Smoking and alcohol use at 4 years after menarche was associated with the change in VAT over the 4-year period, before (p<0.03 and p<0.02, respectively), and after adjustment for total body fat (p<0.01 and p<0.02, respectively).

CONCLUSIONS

In addition to the established health risks, smoking and drinking, even at low levels, appear to be associated with increased VAT deposition in adolescent females.

Magnetic resonance imaging of abdominal adiposity in a large cohort of British children

OBJECTIVE

To describe abdominal adipose tissue distribution in a large sample of contemporary British children; to determine the influence of gender, stage of maturation and body mass index (BMI) on abdominal adipose tissue distribution; and to compare the ability of BMI and waist circumference to predict abdominal adipose tissue.

SUBJECTS AND METHODS

A total of 74 boys (mean age 13.4+/-0.4 years) and 96 girls (mean age 13.5+/-0.5 years) were selected from volunteer children enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC). Height, weight and waist circumference were measured and BMI calculated. Stage of sexual maturation was available for 113 children using a self-report questionnaire based on Tanner's criteria. Magnetic resonance imaging was used to assess subcutaneous abdominal adipose tissue (SAAT) and intra-abdominal adipose tissue (IAAT) volumes and patterning.

RESULTS

Boys had lower levels of IAAT (P=0.036) and SAAT (P=0.003) than girls. IAAT and SAAT were higher in overweight and obese boys and girls when compared with normal weight children (P<0.0001). This pattern was also reflected in waist circumference groups. Boys had higher IAAT/SAAT ratios than girls, indicating proportionately more adipose tissue deposited intra-abdominally (P=0.002). However, both boys and girls deposited less than 10% of their abdominal fat as internal adipose tissue. WC predicted 67.4% of the variance in IAAT (P<0.001), and BMI predicted 84.8% of the variance in SAAT (P<0.001). However, BMI as the best single predictor explained only 8.4% of the variance in the IAAT/SAAT ratio (P<0.001).

CONCLUSIONS

At this age and stage of sexual maturation, the amount of IAAT remains relatively small. WC and BMI offer a feasible alternative to the MRI estimation of IAAT and SAAT, respectively, in a population-based sample of boys and girls. International Journal of Obesity (2008) 32, 91-99; doi:10.1038/sj.ijo.0803780; published online 27 November 2007.

Physical activity, overweight and central adiposity in Swedish children and adolescents: the European Youth Heart Study

Background

The aim of this work was to study the associations of physical activity (PA) and other factors predisposing to overweight, with overweight and central adiposity in children and adolescents.

Methods

A total of 557 Swedish children (9.5 ± 0.3 y) and 517 adolescents (15.6 ± 0.4 y) from the European Youth Heart Study participated in this study. Logistic regression analyses were used to examine the associations of PA, as measured by accelerometry, and other determinants (i.e. television viewing, birth weight, maternal educational level and parental overweight) with total and central adiposity. Body mass index and waist circumference cut-off values proposed by the IOTF and the Bogalusa Heart Study (i.e. waist measures for predicting risk factors clustering, hereinafter called high-risk waist circumference), respectively, were used. Fatness was estimated from skinfold thicknesses and dichotomized using the 85^th sex- and age-specific percentile (high/low).

Results

Children and adolescents who had a low level (first tertile) of vigorous PA, were more likely to be overweight (including obesity) and to have a high-risk waist circumference, than those with a high level (third tertile) of vigorous PA. Similarly, those subjects who had a low or middle level (second tertile) of total PA were more likely to be overweight than those who had a high level of total PA. Among the PA variables, only vigorous PA was associated with high total fatness. Birth weight and television viewing, were also associated with higher odds of having a high-risk waist circumference, but these associations were attenuated once either total or vigorous PA variable was included in the model. Those subjects who had two overweight parents were more likely to be overweight and to have a high-risk waist circumference independently of PA variables, compared to those whose parents were not overweight.

Conclusion

Low levels of total PA and especially vigorous PA may play an important role in the development of overweight and excess of central adiposity in children and adolescents, independently of a number of factors such as television viewing and birth weight. In addition, the data suggest that the association between television viewing and central fat deposition could be attenuated if enough vigorous PA is accumulated. Longitudinal and intervention studies are needed to confirm these findings.