Body fat patterning and blood pressure in children and young adults. The Bogalusa Heart Study

The Get-Up! study: adiposity and blood pressure in Australian toddlers

BACKGROUND

Because the elevated blood pressure (BP) in childhood is strongly associated with overweight and is a risk factor for later cardiovascular disease, a need to comprehend the early development of BP and its association with overweight is needed. We assessed differences of BP by weight status in Australian toddlers.

METHODS

From the Get-Up! Study in Australia, this sample included 265 toddlers (136 boys), aged 19.6 ± 4.2 months. BP was measured with a digital vital signs monitor. Participants were categorized as nonoverweight and overweight according to the World Health Organization definition for body mass index (BMI). Physical activity was captured with activPAL accelerometers, during childcare hours. To test differences in BP between nonoverweight and overweight children, we performed an analysis of covariance adjusting for sex, age, physical activity, and socioeconomic status.

RESULTS

Children with overweight showed higher z systolic BP values (P = .042 for BMI and P = .023 for waist circumference) when compared to nonoverweight children. However, no differences were found for z diastolic BP levels, between overweight and nonoverweight children. After adjustments for potential confounders (socioeconomic status, physical activity, sex, and age), there were no significant differences in BP variables between BMI and waist circumference groups.

CONCLUSIONS

No associations between adiposity and BP levels were found in this sample. The unadjusted results, however, showed that children with higher levels of adiposity (BMI and waist circumference) exhibited higher levels of BP. Additional research is needed to determine which environmental and genetic factors might contribute to pediatric hypertension, particularly among toddlers.

Relationship between BMI and adiposity among different ethnic groups in 2-year-old New Zealand children

Age- and sex-based BMI cut-offs are used to define overweight and obesity, but the relationship between BMI and body composition has not been very well studied in children or compared between children of different ethnic groups. Body size and composition in childhood are also influenced by size at birth. Our aim was to compare body size and composition at 2 years in children with different ethnicity and size at birth. We prospectively followed a multi-ethnic cohort of 300 children born with risk factors for neonatal hypoglycaemia (infants of diabetics, large or small at birth or late preterm) to 2 years corrected age. Complete data on weight, height and head circumference and body composition using bioelectrical impedance 24±1 months corrected age were available in 209 children. At birth, compared with European children, Chinese, Indian and other ethnicity children were lighter, and Indian children had smaller head circumferences, but birth lengths were similar in all ethnic groups. At 2 years, Pacific children were heavier and had higher BMI z scores, and Indian children had smaller head circumferences and lower BMI z scores than those from other ethnic groups. However, fat mass and fat-free mass indices were similar in all groups. At median BMI, fat mass:fat-free mass ratio was 23 % lower in Pacific than in Indian children (0·22 v. 0·27, P=0·03). BMI is not a good indicator of adiposity in this multi-ethnic cohort of 2-year-old New Zealand children.

Longitudinal Changes in Body Composition by Dual-energy Radiograph Absorptiometry Among Perinatally HIV-infected and HIV-uninfected Youth: Increased Risk of Adiposity Among HIV-infected Female Youth

BACKGROUND

Combination antiretroviral therapy has allowed youth with perinatal HIV infection (PHIV+) to live into adulthood, but many youth may experience metabolic and body composition changes that predispose to greater cardiovascular disease (CVD) risk. This longitudinal study evaluated changes in body composition measured by dual-energy radiograph absorptiometry (DXA) in a cohort of PHIV+ youth compared with HIV- controls over a 7-year period.

METHODS

PHIV+ youth and HIV- controls were prospectively enrolled in a single-site study to assess nutrition and CVD risk. Anthropometrics and DXA scans were longitudinally obtained to assess percent body fat and regional fat distribution. Using general linear models, we analyzed differences in body composition and anthropometric measures by sex between PHIV+ youth and controls over time.

RESULTS

Two hundred thirty-five participants (156 PHIV+ and 79 HIV- controls) with at least 1 DXA performed since study enrollment were included for analysis. During the study period, 471 DXAs were obtained in the PHIV+ group and 95 in HIV- controls. PHIV+ females demonstrated greater increase in weight and body mass index over time compared with HIV- females, and significant increases in total percent body fat [estimate = 1.212 (95% confidence interval: 0.837-1.587) percent per year; P < 0.001) and percent trunk fat [1.3818 (95% confidence interval: 0.922-1.84); P < 0.001] compared with HIV- females and PHIV+ males.

CONCLUSIONS

PHIV+ females demonstrate an unfavorable change in fat redistribution and percent body fat over time that exceeds the pattern seen in PHIV+ males or HIV- females. Providers should have heightened awareness of body composition changes of PHIV+ females that may eventually lead to increased CVD risk.

Vitamin D during pregnancy and offspring body composition: a prospective cohort study

BACKGROUND

Evidence regarding the association between gestational vitamin D status and offspring body composition during childhood is inconsistent. Therefore, we aimed to determine the association between maternal vitamin D and offspring lean and fat mass in the Vitamin D in Pregnancy birth cohort.

METHODS

Subjects were mother-child pairs recruited from the Australian-based Vitamin D in Pregnancy cohort study. Mothers were recruited before 16 weeks' gestation and provided a blood sample at both recruitment and at 28-32 weeks' gestation. Serum vitamin D [25(OH)D] was measured by radioimmunoassay (Tyne and Wear, UK). Offspring lean and fat mass were quantified by using dual-energy X-ray absorptiometry (GE Lunar Prodigy, Madison, WI, USA) at 11 years of age.

RESULTS

Median maternal 25(OH)D levels were 55.9 (42.2-73.3) and 56.1 (43.6-73.9) at recruitment and 28-32 weeks' gestation, respectively. Maternal smoking was identified as an effect modifier in the association between maternal vitamin D status at recruitment and offspring body composition. In smokers, but not non-smokers, serum 25(OH)D status at recruitment was negatively associated with offspring fat mass percentage and positively associated with lean mass (both p < 0.05). There was no association with 25(OH)D status at 28-32 weeks' gestation.

CONCLUSIONS

Maternal vitamin D status in early pregnancy, in smokers, is associated with offspring body composition. These important findings warrant confirmation in larger studies and trials.

Towards Precision Medicine for Hypertension: A Review of Genomic, Epigenomic, and Microbiomic Effects on Blood Pressure in Experimental Rat Models and Humans

Compelling evidence for the inherited nature of essential hypertension has led to extensive research in rats and humans. Rats have served as the primary model for research on the genetics of hypertension resulting in identification of genomic regions that are causally associated with hypertension. In more recent times, genome-wide studies in humans have also begun to improve our understanding of the inheritance of polygenic forms of hypertension. Based on the chronological progression of research into the genetics of hypertension as the "structural backbone," this review catalogs and discusses the rat and human genetic elements mapped and implicated in blood pressure regulation. Furthermore, the knowledge gained from these genetic studies that provide evidence to suggest that much of the genetic influence on hypertension residing within noncoding elements of our DNA and operating through pervasive epistasis or gene-gene interactions is highlighted. Lastly, perspectives on current thinking that the more complex "triad" of the genome, epigenome, and the microbiome operating to influence the inheritance of hypertension, is documented. Overall, the collective knowledge gained from rats and humans is disappointing in the sense that major hypertension-causing genes as targets for clinical management of essential hypertension may not be a clinical reality. On the other hand, the realization that the polygenic nature of hypertension prevents any single locus from being a relevant clinical target for all humans directs future studies on the genetics of hypertension towards an individualized genomic approach.

Postnatal height and adiposity gain, childhood blood pressure and prehypertension risk in an Asian birth cohort

OBJECTIVE

There have been hypotheses that early life adiposity gain may influence blood pressure (BP) later in life. We examined associations between timing of height, body mass index (BMI) and adiposity gains in early life with BP at 48 months in an Asian pregnancy-birth cohort.

METHODS

In 719 children, velocities for height, BMI and abdominal circumference (AC) were calculated at five intervals [0-3, 3-12, 12-24, 24-36 and 36-48 months]. Triceps (TS) and subscapular skinfold (SS) velocities were calculated between 0-18, 18-36 and 36-48 months. Systolic (SBP) and diastolic blood pressure (DBP) was measured at 48 months. Growth velocities at later periods were adjusted for growth velocities in preceding intervals, as well as measurements at birth.

RESULTS

After adjusting for confounders and child height at BP measurement, each unit z-score gain in BMI, AC, TS and SS velocities at 36-48 months were associated with 2.3 (95% CI:1.6, 3.1), 2.1 (1.3, 2.8), 1.4 (0.6, 2.2) and 1.8 (1, 2.6) mmHg higher SBP respectively, and 0.9 (0.4, 1.4), 0.9 (0.4, 1.3), 0.6 (0.1, 1.1) and 0.8 (0.3, 1.3) mmHg higher DBP respectively. BMI and adiposity velocities (AC, TS or SS) at various intervals in the first 36 months however, were not associated with BP. Faster BMI, AC, TS and SS velocities, but not height, at 36-48 months were associated with 0.22 (0.15, 0.29), 0.17 (0.10, 0.24), 0.11 (0.04, 0.19) and 0.15 (0.08, 0.23) units higher SBP z-score respectively, and OR=1.46 (95% CI: 1.13-1.90), 1.49 (1.17-1.92), 1.45 (1.09-1.92) and 1.43 (1.09, 1.88) times higher risk of prehypertension/hypertension respectively at 48 months.

CONCLUSIONS

Our results indicated that faster BMI and adiposity (AC, TS or SS) velocities only at the preceding interval before 48 months (36-48 months), but not at earlier intervals in the first 36 months, are predictive of BP and prehypertension/hypertension at 48 months.

Is high waist circumference and body weight associated with high blood pressure in Iranian primary school children?

INTRODUCTION AND OBJECTIVES

The prevalence of overweight, abdominal obesity and hypertension among children has increased worldwide including Iran over several decades. We carried out a study to provide current estimates of the prevalence and trends of hypertension, overweight and obesity along with the relationship between weight status and hypertension in Iranian school-children.

METHOD

This study was carried out among 1184 fifth-grade students, whose ages ranged from 11 to 14 years. Body weight, body mass index (BMI), height and waist circumference (WC), systolic (SBP) and diastolic blood pressure (DBP) were measured.

RESULTS

22.04 and 5.32 % of students were overweight and obese, respectively. The prevalence of overweight and obesity was significantly higher among girls than boys (all p = 0.02), whereas the prevalence of hypertension was significantly higher in boys than girls (p = 0.001). Although 27 % of boys and 24.32 % of girls had abdominal obesity, no significant associations were reported between abdominal obesity and sex (p = 0.12). The prevalence of hypertension in children with normal weight, overweight and obesity, was 3, 9.7 and 17.8 %, respectively (p < 0.01). We have obtained that the mean values of weight and WC were significantly higher in boys than girls. Based on linear regression, every 1 cm increase in abdominal circumference leads to an estimated DBP and SBP increase of 0.173 and 0.164 mmHg, respectively (p < 0.05).

CONCLUSIONS

This study showed a high prevalence of hypertension and obesity in a school-based population in Tehran, Iran, in which the prevalence of hypertension was significantly and positively correlated with weight and WC.

Childhood cardiovascular risk factors, a predictor of late adolescent overweight

Background:

We conducted a prospective study to elucidate the effects of increased cardiovascular risk factors on future weight gain and also the relation between body mass index (BMI) and other cardiovascular risk factors in children and adolescents.

Materials and Methods:

This study was conducted on 1525 nonobese children and adolescents with an age range of 3-16 years old, participating in the 1^st phase and follow-up phases of Tehran Lipid and Glucose Study. The subjects were evaluated 4 times with a 3-year time interval regarding lipid profile status and BMI, and other cardiovascular disease (CVD) risk factors. All the cases had a BMI <85% and had been appraised in at least two evaluation points.

Results:

Cardiovascular risk factors, high-density lipoprotein (HDL) (P = 0.019), low-density lipoprotein (P = 0.016), triglyceride (TG) (P < 0.001), and blood pressure (BP) (P = 0.001); had significant effects on weight gain. There was also no difference between boys and girls and no age trend for increasing weight in both groups. The associations between BMI with cardiovascular risk factors were assessed cross-sectionally. For both sexes, BMI was significantly correlated to systolic and diastolic BP and TG (P = 0.05). For girls, BMI was significantly related to HDL (P = 0.05) regardless to age, but in boys, the relation of BMI with HDL only increased with age (P = 0.05).

Conclusion:

Increased CVD risk factors are predictors of future overweight in childhood and adolescent and increased weight is linked significantly with dyslipidemia and hypertension in this age group.

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.

Impaired cardiac autonomic nervous system function is associated with pediatric hypertension independent of adiposity

BACKGROUND

We examined whether sympathetic nervous system activity influences hypertension status and systolic blood pressure (SBP) independent of adiposity in youth ranging from normal-weight to severe obesity.

METHODS

We examined the association of heart rate variability (HRV) with hypertension status and SBP among youth (6-18 y old; n = 188; 103 female). Seated SBP was measured using an automated cuff. Prehypertension (SBP percentile ≥ 90th to <95th) and hypertension (SBP percentile ≥ 95th) were defined by age-, sex-, and height-norms. Autonomic nervous system activity was measured using HRV via SphygmoCor MM3 system and analyzed for time- and frequency-domains. Total body fat was measured via dual-energy X-ray absorptiometry.

RESULTS

Logistic regression models demonstrated lower values in each time-domain HRV measure and larger low-frequency (LF):high-frequency (HF) ratio to be significantly associated with higher odds of being prehypertensive/hypertensive (11-47% higher odds) independent of total body fat (P < 0.05). In linear regression analysis, lower time-domain, but not frequency-domain, HRV measures were significantly associated with higher SBP independent of total body fat (P < 0.05).

CONCLUSION

These data suggest that impaired cardiac autonomic nervous system function, at rest, is associated with higher odds of being prehypertensive/hypertensive and higher SBP which may be independent of adiposity in youth.

Metabolic and renal adverse effects of antiretroviral therapy in HIV-infected children and adolescents

Worldwide, the benefits of combined antiretroviral (ARV) therapy in morbidity and mortality due to perinatally acquired human immunodeficiency virus infection are beyond question and outweigh the toxicity these drugs have been associated with in HIV-infected children and adolescents to date. In puberty, abnormal body fat distribution is stigmatizating and leads to low adherence to ARV treatment. The other metabolic comorbidities (mitochondrial toxicity, dyslipidemias, insulin resistance and low bone mineral density) and renal toxicity, albeit nonsymptomatic in most children, are increasingly being reported and potentially put this population at risk for early cardiovascular or cerebrovascular atherosclerotic disease, diabetes, pathologic fractures or premature renal failure in the third and fourth decades of life. Evidence from available studies is limited because of methodological limitations and also because of several HIV-unrelated factors influencing, to some degree, the development of these conditions. Current recommendations for the prevention, diagnosis, monitoring and treatment of metabolic and renal adverse effects in HIV-children and adolescents are based on adult studies, observational pediatric studies and experts' consensus. Healthy lifestyle habits (regarding diet, exercise and refraining from toxic substances) and wise use of ARV options are the only preventive tools for the majority of patients. Should abnormal findings arise, switches in one or more ARV drugs have proved useful. Specific therapies are also available for some of these comorbidities, although the experience in the pediatric age is still very scarce. We aim to summarize the epidemiological, clinical and therapeutic aspects of metabolic and renal adverse effects in vertically HIV-infected children and adolescents.

Birth order progressively affects childhood height

BACKGROUND

There is evidence suggesting that first-born children and adults are anthropometrically different to later-borns. Thus, we aimed to assess whether birth order was associated with changes in growth and metabolism in childhood.

METHODS

We studied 312 healthy prepubertal children: 157 first-borns and 155 later-borns. Children were aged 3-10 years, born 37-41 weeks gestation, and of birth weight appropriate-for-gestational-age. Clinical assessments included measurement of children's height, weight, fasting lipid and hormonal profiles and DEXA-derived body composition.

RESULTS

First-borns were taller than later-borns (P < 0·0001), even when adjusted for parents' heights (0·31 vs 0·03 SDS; P = 0·001). There was an incremental height decrease with increasing birth order, so that first-borns were taller than second-borns (P < 0·001), who were in turn taller than third-borns (P = 0·007). Further, among sibling pairs both height SDS (P = 0·009) and adjusted height SDS (P < 0·0001) were lower in second- vs first-born children. Consistent with differences in stature, first- (P = 0·043) and second-borns (P = 0·003) had higher IGF-I concentrations than third-borns. Both first- (P < 0·001) and second-borns (P = 0·004) also had reduced abdominal adiposity (lower android fat to gynoid fat ratio) when compared with third-borns. Other parameters of adiposity and blood lipids were unaffected by birth order.

CONCLUSIONS

First-borns were taller than later-born children, with an incremental height reduction from first to third birth order. These differences were present after correction for genetic height, and associated to some extent with alterations in plasma IGF-I. Our findings strengthen the evidence that birth order is associated with phenotypic changes in childhood.

Pre-pubertal children born post-term have reduced insulin sensitivity and other markers of the metabolic syndrome

BACKGROUND

There are no data on the metabolic consequences of post-term birth (≥42 weeks gestation). We hypothesized that post-term birth would adversely affect insulin sensitivity, as well as other metabolic parameters and body composition in childhood.

METHODS

77 healthy pre-pubertal children, born appropriate-for-gestational-age were studied in Auckland, New Zealand: 36 born post-term (18 boys) and 41 (27 boys) born at term (38-40 weeks gestation). Primary outcome was insulin sensitivity measured using intravenous glucose tolerance tests and Bergman's minimal model. Other assessments included fasting hormone concentrations and lipid profiles, body composition from whole-body dual-energy X-ray absorptiometry, 24-hour ambulatory blood pressure monitoring, and inflammatory markers.

RESULTS

Insulin sensitivity was 34% lower in post-term than in term children (7.7 vs. 11.6 x10⁻⁴·min⁻¹·(mU/l); p<0.0001). There was a compensatory increase in acute insulin response among post-term children (418 vs 304 mU/l; p=0.037), who also displayed lower glucose effectiveness than those born at term (2.25 vs 3.11 x10⁻²·min⁻¹; p=0.047). Post-term children not only had more body fat (p=0.014) and less fat-free mass (p=0.014), but also had increased central adiposity with more truncal fat (p=0.017) and greater android to gynoid fat ratio (p=0.007) compared to term controls. Further, post-term children displayed other markers of the metabolic syndrome: lower normal nocturnal systolic blood pressure dipping (p=0.027), lower adiponectin concentrations (p=0.005), as well as higher leptin (p=0.008) and uric acid (p=0.033) concentrations. Post-term boys (but not girls) also displayed a less favourable lipid profile, with higher total cholesterol (p=0.018) and LDL-C (p=0.006) concentrations, and total cholesterol to HDL-C ratio (p=0.048).

CONCLUSIONS

Post-term children have reduced insulin sensitivity and display a number of early markers of the metabolic syndrome. These findings could have important implications for the management of prolonged pregnancies. Future studies need to examine potential impacts later in life, as well as possible underlying mechanisms.

Increasing maternal age is associated with taller stature and reduced abdominal fat in their children

BACKGROUND

Maternal age at childbirth continues to increase worldwide. We aimed to assess whether increasing maternal age is associated with changes in childhood height, body composition, and metabolism.

METHODS

277 healthy pre-pubertal children, born 37-41 weeks gestation were studied. Assessments included: height and weight corrected for parental measurements, DEXA-derived body composition, fasting lipids, glucose, insulin, and hormonal profiles. Subjects were separated according to maternal age at childbirth: <30, 30-35, and >35 years.

RESULTS

Our cohort consisted of 126 girls and 151 boys, aged 7.4 ± 2.2 years (range 3-10); maternal age at childbirth was 33.3 ± 4.7 years (range 19-44). Children of mothers aged >35 and 30-35 years at childbirth were taller than children of mothers aged <30 years by 0.26 (p = 0.002) and 0.23 (p = 0.042) SDS, respectively. There was a reduction in childhood BMISDS with increasing maternal age at childbirth, and children of mothers aged >35 years at childbirth were 0.61 SDS slimmer than those of mothers <30 years (p = 0.049). Children of mothers aged 30-35 (p = 0.022) and >35 (p = 0.036) years at childbirth had abdominal adiposity reduced by 10% and 13%, respectively, compared to those in the <30 group. Children of mothers aged 30-35 years at childbirth displayed a 19% increase in IGF-I concentrations compared to offspring in <30 group (p = 0.042). Conversely, IGF-II concentrations were lower among the children born to mothers aged 30-35 (6.5%; p = 0.004) and >35 (8.1%; p = 0.005) compared to those of mothers aged <30 years. Girls of mothers aged 30-35 years at childbirth also displayed improved HOMA-IR insulin sensitivity (p = 0.010) compared to girls born to mothers aged <30 years.

CONCLUSIONS

Increasing maternal age at childbirth is associated with a more favourable phenotype (taller stature and reduced abdominal fat) in their children, as well as improved insulin sensitivity in girls.

Obesity and cardiac autonomic nerve activity in healthy children: Results of the toyama birth cohort study

OBJECTIVES

To determine the relationship between obesity and cardiac autonomic nerve activity in healthy children.

METHODS

16 healthy male children comprising of 9 nonobese and 7 obese subjects (body mass index > 19.1 kg/m(2)) aged 8-9 years were selected. Electrocardiograms were measured for 10 min. under controlled ventilation (0.25 Hz) in the supine position. Consecutive 256-second RR interval data were transformed by the Fast Fourier Transform method into power spectral data. Very low frequency (VLF; 0.003-0.04 Hz), low frequency (LF; 0.04-0.15Hz), high frequency (HF; 0.15-0.40Hz), and total power (TP; 0.003-0.40Hz) were calculated and transformed into a natural logarithm (In). Normalized units (nu) were also calculated as follows: LFnu=LF/(TP-VLF)x100. HFnu=HF/(TP-VLF)x100. Low/high-frequency ratio (LHR) was calculated as LF divided by HF. Unpaired t test was performed to compare the 2 groups.

RESULTS

TP In and HFnu, reflecting cardiac parasympathetic nerve activity, in obese children were significantly lower than those in nonobese children. In contrast, LFnu and LHF, reflecting cardiac sympathetic nerve activity, in obese children were significantly higher than those in nonobese children.

CONCLUSIONS

These findings suggest that obese children have higher sympathetic nerve activity and lower parasympathetic nerve activity than nonobese children.

Obesity is a risk factor for fracture in children but is protective against fracture in adults: a paradox

With the rise in obesity worldwide, an important debate has developed as to whether excess fat has a detrimental or protective effect on skeletal health in children and adults. Obese children appear to be over represented in fracture groups and recent evidence suggests that fat may be detrimental to bone accrual in children, although this effect may be confined to adolescence during rapid skeletal growth. Fat induced alterations in hormonal factors and cytokines during growth may play a pivotal role in disturbing bone accrual. In contrast, the widely accepted opinion is that fat appears to be protective of bone in adults and minimises bone loss in postmenopausal women. Recent evidence suggests that in adults, site specific fat depots may exert differing effects on bone (with visceral fat acting as a pathogenic fat depot and subcutaneous fat exerting protective effects), and that the effects of fat mass on bone and fracture risk may vary by skeletal site; obesity protects against hip and vertebral fractures but is a risk factor for fractures of the humerus and ankle. The incidence of fracture during adolescence is rising and osteoporosis remains a considerable health burden in older adults. Understanding the effects of fat mass on bone during growth and early adulthood is vital in informing future health strategies and pharmacotherapies to optimise peak bone mass and prevent fracture.

Body fat distribution in perinatally HIV-infected and HIV-exposed but uninfected children in the era of highly active antiretroviral therapy: outcomes from the Pediatric HIV/AIDS Cohort Study

BACKGROUND

Associations between abnormal body fat distribution and clinical variables are poorly understood in pediatric HIV disease.

OBJECTIVE

Our objective was to compare total body fat and its distribution in perinatally HIV-infected and HIV-exposed but uninfected (HEU) children and to evaluate associations with clinical variables.

DESIGN

In a cross-sectional analysis, children aged 7-16 y in the Pediatric HIV/AIDS Cohort Study underwent regionalized measurements of body fat via anthropometric methods and dual-energy X-ray absorptiometry. Multiple linear regression was used to evaluate body fat by HIV, with adjustment for age, Tanner stage, race, sex, and correlates of body fat in HIV-infected children. Percentage total body fat was compared with NHANES data.

RESULTS

Males accounted for 47% of the 369 HIV-infected and 51% of the 176 HEU children. Compared with HEU children, HIV-infected children were older, were more frequently non-Hispanic black, more frequently had Tanner stage ≥3, and had lower mean height (-0.32 compared with 0.29), weight (0.13 compared with 0.70), and BMI (0.33 compared with 0.63) z scores. On average, HIV-infected children had a 5% lower percentage total body fat (TotF), a 2.8% lower percentage extremity fat (EF), a 1.4% higher percentage trunk fat (TF), and a 10% higher trunk-to-extremity fat ratio (TEFR) than did the HEU children and a lower TotF compared with NHANES data. Stavudine use was associated with lower EF and higher TF and TEFR. Non-nucleotide reverse transcriptase inhibitor use was associated with higher TotF and EF and lower TEFR.

CONCLUSION

Although BMI and total body fat were significantly lower in the HIV-infected children than in the HEU children, body fat distribution in the HIV-infected children followed a pattern associated with cardiovascular disease risk and possibly related to specific antiretroviral drugs.

Changes in anthropometric characteristics and blood pressure during adolescence

BACKGROUND

Studies suggest that sex differences in blood pressure (BP) are established early in life. Sex differences in BP increases that occur during adolescence may be due to differences in changes in anthropometric characteristics.

METHODS

Using sex-specific individual growth models, we assessed the effect of height, body mass index (BMI; kg/m), waist circumference, and triceps and subscapular skinfold thickness on changes in systolic BP in a cohort of 1293 adolescents in Montreal, Canada. BP and anthropometry were assessed biannually (1999/2000, 2002, 2004) at mean ages 12.8, 15.2, and 17.0.

RESULTS

On average, systolic BP increased by 11.1 mm Hg in boys and 3.2 mm Hg in girls during 5 years. Changes in height explained half of the overall increase in systolic BP in boys and virtually all of the increase in systolic BP in girls. No meaningful sex differences were observed in the association of changes in BMI, waist circumference, and triceps and subscapular skinfold thickness with systolic BP change during 5 years. Increases in 1 BMI unit, 1 cm waist circumference, or 1 mm triceps or subscapular skinfold thickness were associated with increases of 0.7, 0.24, 0.3, and 0.4 mm Hg systolic BP, respectively.

CONCLUSIONS

Although sex differences in mean systolic BP changes during adolescence were largely attributable to differences in gains in height, the effect of gaining weight or body fat on systolic BP change was similar in boys and girls.

Is term newborn body composition being achieved postnatally in preterm infants?

BACKGROUND

The American Academy of Pediatrics (AAP) recommends that preterm infants' growth duplicates fetal growth rates and that body composition replicates in utero body composition.

AIMS

To compare the total body fat mass between preterm infants assessed at term corrected age and full-term newborns, and to investigate the effects of gestational age, gender, weight increase, being breast fed on total adiposity.

STUDY DESIGN

Prospective observational study.

SUBJECTS

One hundred and ten preterm infants [mean (SD) gestational age: 29.9 (2.3) weeks; birth weight: 1118 (274) g], and 87 full term [mean (SD) 38.6 (1.21) weeks, 3203 (385) g], breastfed infants.

OUTCOME MEASURES

Growth and body composition by means of a pediatric air displacement system were assessed at term corrected age in preterm infants and on day 3 of life in full term infants.

RESULTS

Weight, length and head circumference were smaller in the preterm group as compared to the term group. Mean (SD) percentage of fat mass in preterm infants was significantly higher as compared to term infants [14.8 (4.4) vs 8.59 (3.71), P<0.0001]. Fat mass was negatively correlated with gestational age (P<0.001), and positively associated with weight increase (P< 0.05).

CONCLUSIONS

Our data suggest that body composition, in terms of fat mass, in preterm infants at term corrected age is different from that of full term newborns.

Relationship of anthropometric measurements of body fat distribution to metabolic profile in premenopausal women

Regional fat distribution has emerged as an independent predictor of metabolic aberrations including glucose intolerance, hyperinsulinemia, insulin resistance, hyperlipidemia and hypertension. We investigated the comparative efficacy of various body fat distribution indices in predicting these aberrations. The relationship of circumferential ratios, skinfold measurements, and computerized tomography (CT)-derived indices of intra- and extra-abdominal fat distribution to the metabolic variables and blood pressure was examined in a cohort of healthy premenopausal women. All indices denoting preponderance of fat in the central, upper body or abdominal region were predictive of the metabolic profile. The subscapular skinfold, subscapular-triceps ratio, waist-hip ratio (WHR), and the CT derived intra-abdominal fat area (CT-IFA) were closely related to alterations in glucose and insulin concentrations independent of age and obesity. The WHR and CT-IFA were better predictors of plasma triglyceride levels and blood pressure profile and thus the overall aberrations than skinfold measurements. Despite a high degree of intercorrelation between the anthropometric indices measured, only the relationship of WHR to CT-IFA remained significant after adjusting for the effects of age and degree of adiposity, suggesting that WHR indexes not only the relative distribution of truncal to gluteofemoral subcutaneous fat but also the abundance of intra-abdominal or visceral fat depots. The greater reproducibility of CT-IFA and WHR also suggests that these measurements are the most useful in predicting the regional obesity-associated metabolic abnormalities with their morbidity and mortality risks.

Cardiovascular Risks Associated With Obesity in Children and Adolescents

Introduction: The aim of this paper is to review the cardiovascular (CVS) risks associated with obesity in children and adolescents. Both short-term and long-term CVS consequences, the mechanisms of how these develop and the measures that can alter or reverse these CVS events are reviewed. Materials and Methods:Selected publications include original articles and review papers that report on studies of CVS risks and consequences related to childhood obesity. Some papers that contain data from adults studies are also included if the contents help to explain some underlying mechanisms or illustrate the continuation of related CVS changes into adulthood. Results: Obese children and adolescents have an increased risk for CVS complications that include elevation of blood pressure, clustering of CVS risk factors (Metabolic Syndrome), changes to arterial wall thickness, elasticity and endothelium, as well as changes in left ventricular structure and function. Some of these cardiovascular problems may be initiated or potentiated by obstructive sleep apnoea that can accompany obesity in children. Many of such changes have been noted to reverse or improve with weight reduction. Conclusions:Early development of CVS risks in obese children and the possible continuation of CVS complications into adulthood have been observed. Obstructive sleep apnoea in obese children can further contribute to such CVS risks. These findings underscore the importance of prevention of childhood obesity as a priority over management of obesity in children. The prevalence of obesity has risen by three-folds or more in many countries since 1980. In 2005, it was estimated that globally there are about 1.6 billion overweight adults and at least 400 million of them are obese. This increase in the prevalence of adults being overweight and obese comes with a heavy price. The cost of healthcare has significantly increased and is expected to increase even more because of the close association between obesity and various chronic diseases. Key words: Endothelial function, Hypertension, Metabolic syndrome, Obstructive sleep apnoea

Association between short sleeping hours and overweight in adolescents: results from a US Suburban High School survey

Insufficient sleep may lead to adverse health effects, influencing body weight. This study quantified the prevalence of short sleep and the association between sleep duration and overweight in a sample of suburban students. Cross-sectional study was conducted in 2004, involving 529 students from Bay High School, Bay Village, OH, USA, using self-administered questionnaires assessing lifestyle and sleep behaviors. Students with a body mass index Z Score >85th percentile for sex and age were deemed overweight. Ninety percent of students reported average sleep time less than 8 h on school nights, with 19% reported less than 6 h of sleep per night. Twenty percent of the sample were overweight. Overweight was significantly associated with the male gender, increased caffeine consumption, and short sleep duration. Compared with students sleeping >8 h, the age and gender-adjusted odds ratio of overweight was 8.53 (95% CI: 2.26, 32.14) for those with <5 h sleep (P = 0.0036); 2.79 (1.03, 7.55) for those with 5-6 h sleep; 2.81 (1.14, 6.91) for those with 6-7 h sleep; and 1.29 (0.52, 3.26) for those with 7-8 h sleep. Short sleep duration was common and associated with overweight with evidence of a "dose-response" relationship. These results confirm a high prevalence of short sleep among suburban high school students and provide additional support suggesting significant association between short sleeping hours and overweight.

Regional fat distribution in children born preterm evaluated at school age

Children born preterm may have aberrant adiposity. At school age, we evaluated body fat and fat distribution in 45 former preterm infants (birth weight < or = 1800 g and gestational age < 34 weeks) and 40 children born at term using dual-energy x-ray absorptiometry. Children born preterm exhibited lower total body fat mass and total body fat mass index compared with children born at term. Fat mass indexes in the limbs but not the trunk were lower in children born preterm than in children born at term. In conclusion, children born preterm, evaluated at school age, may be at risk for altered regional adiposity.

Interventions to prevent or treat obesity in preschool children: a review of evaluated programs

OBJECTIVE

To identify effective programs to prevent or treat overweight among 2- to <6-year-old children.

RESEARCH METHODS AND PROCEDURES

We searched six databases to identify evaluated intervention programs assessing changes in weight status or body fat and systematically summarized study attributes and outcomes.

RESULTS

Four of the seven studies (two intervention, two prevention) documented significant reductions in weight status or body fat. Among these, three sustained reductions at 1 or 2 years after program initiation, three incorporated a framework/theory, two actively and one passively involved parents, three included multicomponent strategies, and all four monitored behavioral changes. Of the three (prevention) studies that did not show reduction in weight or fat status, all performed assessments between 4 and 9 months after program initiation, and one used a multicomponent strategy. Other significant changes reported were reductions in television viewing, cholesterol, and parental restriction of child feeding.

DISCUSSION

The paucity of studies limits our ability to generalize findings. Among the available studies, multicomponent programs with 1- to 2-year follow-up in clinics or child care settings were successful in their impact on weight; they were likely enhanced by parental involvement. Both treatment programs and two of five prevention programs reduced weight/fat status. Our review highlights the need to evaluate more programs, advocate for use of a framework/behavioral theory and objective behavioral measures, further examine the impact of involving parents and the impact of intervention duration and follow-up time, strengthen prevention programs, and further evaluate successful programs in other settings and among other racial/ethnic groups.

Relationship between body composition and blood pressure in Bahraini adolescents

The objective of the present study was to examine the relationship between body composition and blood pressure (BP) in Bahraini adolescents. A sample of 504 Bahraini schoolchildren aged 12–17 years (249 boys and 255 girls) was selected using a multi-stage stratified sampling procedure. BP measurements were performed on the students. Anthropometric data including weight, height, waist circumference (WC), hip circumference, and triceps, subscapular and medial calf skinfold thicknesses were also collected. BMI, percentage body fat, waist:hip (WHR), and subscapular:triceps skinfold ratio were calculated. Mean systolic BP and mean diastolic BP were higher in males than in females. Weight and height in boys and weight only in girls were significantly associated with systolic BP independent of age or percentage fat. Nearly 14% of the adolescents were classified as having high BP. BMI and percentage body fat were significantly and positively associated with the risk of having high BP in the boys and girls. Adolescents with high WHR or WC, as indicators for central obesity, tended to have higher BP values. The results from the present study indicate that obesity influences the BP of Bahraini adolescents and that simple anthropometric measurements such as WHR and WC are useful in identifying children at risk of developing high BP. These findings together with the known tracking of BP from adolescence into adulthood underline the importance of establishing intervention programmes in order to prevent the development of childhood and adolescent obesity.

High blood pressure in school children: prevalence and risk factors

Background

The purpose of this study was to determine the prevalence of high blood pressure (HBP) and associated risk factors in school children 8 to 13 years of age.

Methods

Elementary school children (n = 1,066) were examined. Associations between HBP, body mass index (BMI), gender, ethnicity, and acanthosis nigricans (AN) were investigated using a school based cross-sectional study. Blood pressure was measured and the 95^th percentile was used to determine HBP. Comparisons between children with and without HBP were utilized. The crude and multiple logistic regression adjusted odds ratios were used as measures of association.

Results

Females, Hispanics, overweight children, and children with AN had an increased likelihood of HBP. Overweight children (BMI ≥ 85^th percentile) and those with AN were at least twice as likely to present with HBP after controlling for confounding factors.

Conclusion

Twenty one percent of school children had HBP, especially the prevalence was higher among the overweight and Hispanic group. The association identified here can be used as independent markers for increased likelihood of HBP in children.

Mini Review: Physical activity and fitness and its relations to cardiovascular disease risk factors in children

OBJECTIVES

This paper aim to review the newest literature linking physical inactivity and low fitness to metabolic disorders including cardiovascular disease (CVD) risk factors and obesity.

METHODS

There is a rationale for early prevention of CVD if (a) children have a risk factor profile, where risk for future disease is increased, (b) physical activity and CVD risk factors track into adulthood, and (c) increased physical activity can improve the risk factor profile. We reviewed the evidence for a progressive evolution of atherosclerosis starting in childhood, and also that physical activity decreases the rate of the process through several mechanisms. Among the central mechanisms mediating the effect of physical activity are (a) increased insulin sensitivity, (b) a non-insulin-dependent glucose uptake, which causes lower insulin release, (c) an improved ratio between HDL and LDL cholesterol because of increased activity of lipoprotein lipase, and d) improved function of other metabolic hormones and enzymes for fat metabolism.

RESULTS

The association between CVD risk factors and physical activity/fitness is weak, when risk factors are analysed isolated. In the normal healthy population of children, studies have shown that risk factors cluster and this clustering is strongly related to low physical activity or fitness. In European children it has been found that as many as 15% of 9-y-old children has clustered risk. Most of the overweight and obese children are among these, but many of the children are lean inactive children, who may later become overweight because of insulin resistance.

CONCLUSION

It can be concluded that there is a large potential for primary prevention of CVD in European children, and lifestyle changes including increased physical activity as one of the key actions should be initiated.

Associations between adiposity, family history of CHD and blood pressure in 3–8 year-old children

The purpose of this study was to examine the relationships between overall and central adiposity, a family history of coronary heart disease (FHCHD), and blood pressure (BP) in young children. We were specifically interested in determining whether the relationship between adiposity and BP was modified by a FHCHD. Subjects were 130 (68 males, 62 females) young children (mean age 6.0 years). Indicators of adiposity included the body mass index, waist circumference, skinfold thickness, and body composition determined by dual energy X-ray absorbtiometry (DXA). BP was measured by standard procedures. FHCHD was reported by the parent on a questionnaire. Approximately 19% of the total sample was classified as overweight and almost 50% were classified as prehypertensive (22.4%) or hypertensive (24.8%). In the total sample, 21 of 27 correlations were significant and ranged from 0.03 to 0.52. Correlations for systolic blood pressure appeared to be stronger in female subjects. Most of the correlations for diastolic blood pressure and mean arterial pressure were significant in both sexes and, in general, ranged between 0.30 and 0.50. Overweight status was significantly associated with high BP (crude odds ratio=3.65, 95% confidence intervals 1.40-9.49). There were no significant associations between a positive FHCHD and BP, and the correlations between BMI, WC, and BP were similar in magnitude in subjects with and without a FHCHD. In conclusion, both overall and central adiposity are important determinants of resting BP in young children. A FHCHD was not associated with BP and nor were the associations between adiposity and BP modified by a FHCHD.

Overweight among low-income preschool children associated with the consumption of sweet drinks: Missouri, 1999-2002

OBJECTIVE

To examine the association between sweet drink consumption and overweight among preschool children.

METHODS

A retrospective cohort design was used to examine the association between sweet drink consumption and overweight at follow-up among 10904 children who were aged 2 and 3 years and had height, weight, and Harvard Service Food Frequency Questionnaire data collected between January 1999 and December 2001 and height and weight data collected 1 year later. Sweet drinks included vitamin C-containing juices, other juices, fruit drinks, and sodas as listed on the Harvard Service Food Frequency Questionnaire. Logistic regression was used to adjust for age; gender; race/ethnicity; birth weight; and intake of high-fat foods, sweet foods, and total calories. Results were stratified by baseline BMI.

RESULTS

Among children who were normal or underweight at baseline (BMI <85th percentile), the association between sweet drink consumption and development of overweight was positive but not statistically significant. Children who were at risk for overweight at baseline (BMI 85th-<95th percentile) and consumed 1 to <2 drinks/day, 2 to <3 drinks/day, and > or =3 drinks/day were, respectively, 2.0 (95% confidence interval [CI]: 1.3-3.2), 2.0 (95% CI: 1.2-3.2), and 1.8 (95% CI: 1.1-2.8) times as likely to become overweight as the referent (<1 drink/day). Children who were overweight at baseline (BMI > or =95th percentile) and consumed 1 to <2 drinks/day, 2 to <3 drinks/day, and > or =3 drinks/day were, respectively, 2.1, 2.2, and 1.8 times as likely to remain overweight as the referent.

CONCLUSIONS

Reducing sweet drink consumption might be 1 strategy to manage the weight of preschool children. Additional studies are needed to understand the mechanism by which such consumption contributes to overweight.

Sex-specific fat distribution is not linear across pubertal groups in a multiethnic study

OBJECTIVE

To investigate sexual dimorphism and race differences in fat distribution (android/gynoid) before and during puberty.

RESEARCH METHODS AND PROCEDURES

Fat distribution was measured by skinfold thickness and DXA in healthy African-American, Asian, and white subjects (n = 920), divided into pre-, early, and late pubertal groups.

RESULTS

Gynoid fat masses adjusted for covariates were lower in late pubertal compared with prepubertal boys, but were not consistently greater in late pubertal compared with prepubertal girls. Progression of sex-specific fat distribution with increasing maturation was present in Asians only. Among African-American and white subjects, early pubertal boys had greater gynoid fat mass compared with the prepubertal group, whereas early pubertal girls had less gynoid fat mass compared with the prepubertal group. Sexual dimorphism in fat distribution was present in all pubertal groups, except among whites at early puberty. Among girls, Asians had lower gynoid fat than whites and African Americans in all pubertal groups. Among boys, Asians had less gynoid fat by DXA in early puberty and late puberty.

DISCUSSION

Comparison among races demonstrated differences in sexual dimorphism and sex-specific fat distribution with progression in pubertal group. However, in all race groups, the fat distribution of late pubertal boys was more "male" or "android" than prepubertal boys, but late pubertal girls did not differ consistently from prepubertal girls. These findings suggested that the greater sexual dimorphism of fat distribution in late puberty compared with prepuberty may be attributable to larger changes in boys with smaller changes in girls.

Persistent hypercholesterolemia is associated with the development of obesity among girls: the Bogalusa Heart Study

BACKGROUND

Obesity is associated with cardiovascular disease (CVD) risk factors. Cross-sectional data suggest that hypercholesterolemia is associated with the development of childhood obesity.

OBJECTIVE

The objective was to assess age-related changes in relative weight and the association between relative weight and CVD risk factors in hypercholesterolemic and nonhypercholesterolemic children who were nonobese at baseline.

DESIGN

Data on relative weight and CVD risk factors were extracted from the Bogalusa Heart Study for nonobese 5-6-y-old black and white hypercholesterolemic (LDL cholesterol > 75th percentile; n = 58) and nonhypercholesterolemic (LDL cholesterol < 60th percentile; n = 215) children (41% black, 52% girls) who were also assessed 3 and 6 y later. Changes in body mass index (BMI) and CVD risk factors were assessed as a function of age, sex, race, and cholesterol concentration.

RESULTS

BMI increased more in the hypercholesterolemic (n = 31) than in the nonhypercholesterolemic (n = 111) girls during the 6 y of follow-up but was not significantly different between hypercholesterolemic (n = 27) and nonhypercholesterolemic (n = 104) boys aged 5-12 y. Associations between BMI and the risk factors blood pressure, insulin, and blood lipids were observed to be stronger with increasing age and, in some cases, stronger in hypercholesterolemic children and girls.

CONCLUSIONS

Hypercholesterolemia is associated with increased relative weight in girls. The increased relative weight, even at an early age, is associated with a deleterious effect on blood lipids and other CVD risk factors in hypercholesterolemic children, although the strength of these associations is sex dependent.

A dose-response relationship between short sleeping hours and childhood obesity: results of the Toyama Birth Cohort Study

BACKGROUND

Short sleeping hours could cause obesity through increased sympathetic activity, elevated cortisol secretion and decreased glucose tolerance. The aim of this study was to clarify parental and lifestyle factors, particularly sleeping habits, associated with obesity in Japanese children.

METHODS

Between June and July 1996, 8274 children (4194 males and 4080 females) aged 6-7 years living in Toyama prefecture, Japan, were investigated by questionnaire survey and the collection of anthropometric data. Subjects with a body mass index (BMI; weight in kg divided by square of height in m) greater than the age- and sex-specific cut-off points linked to adulthood overweight (BMI of 25 kg/m2 or more) were defined as obese subjects. Parental obesity was defined as a BMI of 25 kg/m2 or more. Logistic regression analysis was performed to evaluate the strength of the relationships between parental obesity or lifestyle factors and childhood obesity, adjusted for possible confounding factors.

RESULTS

Parental obesity, long hours of TV watching and physical inactivity were significantly associated with childhood obesity. Although wake-up time was not related to obesity, there was a significant dose-response relationship between late bedtime or short sleeping hours and childhood obesity. Compared with children with 10 or more hours of sleep, the adjusted odds ratio was 1.49 (95% confidence interval 1.08-2.14) for those with 9-10 h sleep, 1.89 (1.34-2.73) for those with 8-9 h sleep and 2.87 (1.61-5.05) for those with <8 h sleep, after adjustment for age, sex, parental obesity and other lifestyle factors.

CONCLUSION

A strong inverse association was observed in the relationship between sleeping hours and childhood obesity. Longitudinal research will be required to confirm this causality.

Abdominal fat and birth size in healthy prepubertal children

BACKGROUND

Studies examining the foetal origins hypothesis suggest that small birth size may be a marker of foetal adaptations that programme future propensity to adult disease. We explore the hypothesis that birth size may relate to fat distribution in childhood and that fat distribution may be a link between birth size and adult disease.

OBJECTIVE

To investigate the relationship between birth size and abdominal fat, blood pressure, lipids, insulin and insulin:glucose ratio in prepubertal children.

DESIGN

Cross-sectional study, based on a birth cohort of consecutive full-term births.

SUBJECTS

Two hundred and fifty-five (137 females) healthy, 7- and 8-y-old children.

MEASUREMENTS

Body composition and abdominal fat was measured by dual energy X-ray absorptiometry. Lipid, glucose and insulin profiles were measured after an overnight fast and an automated BP monitor was used for blood pressure measurements.

RESULTS

There was a negative association between abdominal fat and birth weight s.d. score across a range of normal birth weights (beta=-0.18; 95% CI=-0.31 to -0.04, P=0.009) and a positive association with weight s.d. score at 7/8 y (beta=0.35; 95% CI=0.24 to 0.46, P<0.001). Children who were born with the lowest weight s.d. score and had the greatest weight s.d. score at 7/8 y had significantly more (P<0.001) abdominal fat, as a percentage of total fat (6.53+/-1.3%) than those who had the highest birth weight s.d. score and the lowest weight s.d. score at 7/8 y (4.14+/-0.5%). Similar results were seen if head circumference, but not ponderal index, was used as an indicator of birth size. Increased abdominal fat was associated with higher total cholesterol:HDL cholesterol, higher triglyceride concentration and increased diastolic blood pressure.

CONCLUSIONS

Birth weight independently predicted abdominal fat. Children with the highest amount of abdominal fat were those who tended to be born lighter and gained weight centiles. Increased abdominal fat was associated with precursor risk factors for ischaemic heart disease.

Prevalence of overweight in a triethnic pediatric population of San Antonio, Texas

OBJECTIVES

To investigate the prevalence of overweight among different ethnic and gender groups of children and adolescents in the San Antonio, Texas, area and to compare the prevalence with that of the US national figures.

DESIGN

Cross-sectional study

SUBJECTS

A total of 7208 schoolchildren in kindergarten through 12th grade. There were 4215 Mexican American (MA) (58.5%), 2040 non-Hispanic white (NHW) (28.3%) and 953 African American (AA) (13.2%) subjects.

MEASUREMENTS

Weight, height and skinfold thicknesses.

RESULTS

The body mass index (BMI, kg/m2) values of MA boys were almost consistently and significantly (P<0.05) larger than NHW boys and showed a tendency to be larger than AA boys, beginning as early as age 6 and continuing through age 17. Although rarely significant, a similar trend in ethnic difference was also noted for girls, with the smallest BMI seen in NHW girls. The subscapular skinfold thickness (SST) for MA boys and girls was significantly (P<0.05) larger than that for NHW counterparts and showed a tendency to be larger than AA counterparts. No significant ethnic differences were present in the triceps skinfold thickness (TST) for girls, but MA boys' TST were occasionally larger (P<0.05) than other ethnic-gender groups. Girls' TST were frequently larger (P<0.05) than boys for each ethnic groups. Using the population data from the National Health and Nutrition Examination Survey (NHANES) I as reference, the prevalence of overweight (BMI> or =95th percentile) was greater in MA (15-28%) and AA (11-29%) boys and girls than in NHW (7-17%) counterparts. The combined prevalence of overweight and 'at risk of overweight' (BMI>85th percentile) was much larger in MA boys (40-50%), MA girls (34-52%), and AA girls (33-51%) than other subgroups. The onset of overweight is quite early, starting at 5-6 y of age, especially in girls. Compared to the data from national surveys, the prevalence of overweight found in this study is higher than reported nationally. We found a marked increase in the skinfold thickness, especially SST for boys, but the increase is less for girls.

CONCLUSIONS

The prevalence of overweight is higher in MA boys and girls and AA girls than other ethnic-gender groups in the San Antonio, Texas, area. The prevalence of childhood overweight in the San Antonio area is higher than national figures. The findings of increasing prevalence and early onset of childhood overweight are concerning, because these are known risk factors for diabetes and diseases of many other organ systems. Measures to prevent, reduce or treat childhood obesity are urgently needed.

Psychosocial differences associated with body weight among female adolescents: the importance of body image

PURPOSE

To determine whether overweight female adolescents differ from normal and underweight female adolescents with respect to a set of psychosocial factors, while controlling for body image.

METHODS

Female participants of the National Longitudinal Study of Adolescent Health (n = 3197) were selected for analysis. Multivariate Analysis of Variance (MANOVA) was used to test whether overweight subjects differed from normal and underweight subjects with respect to measures of depression, self-esteem, trouble in school, school connectedness, family connectedness, sense of community, autonomy, protective factors, and grades. Stepdown F-tests and discriminant function coefficients provided information regarding the strength of specific factors in contributing to overall differences.

RESULTS

MANOVA revealed significant differences between groups on the combined set of psychosocial factors. Self-esteem defined the difference in a positive direction while grades defined the difference inversely. When controlling for body image, multidimensional group differences were still evident; however, self-esteem was no longer a significant contributing variable.

CONCLUSIONS

While overweight female adolescents seem to suffer from low self-esteem, it may be explained by body image. Efforts should be directed toward encouraging and supporting healthy eating patterns and physical activity while encouraging students to recognize personal strengths not related to physique.

Association of fasting blood sugar level, insulin level, and obesity with left ventricular mass in healthy children and adolescents: The Bogalusa Heart Study

BACKGROUND

Insulin resistance, often associated with obesity, is hypothesized to be involved in the pathogenesis of essential hypertension and may relate to increased left ventricular mass (LVM).

METHODS

We examined correlations between echocardiographic LVM and fasting blood glucose and insulin levels in a cross-section of 216 black and white healthy children and young adults aged 13 to 27 years in Bogalusa, Louisiana. Anthropometric measurements and blood pressure readings were also obtained.

RESULTS

Positive bivariate correlation was found between fasting blood glucose level and LVM corrected for growth (LVMC) (LVMC = LVM/Height2.7) with all race/sex groups combined (r = 0.17, P </=.03). Multivariate analyses in a model including race, sex, age, and measures of body size showed no significant correlations between fasting blood glucose level, insulin level, and LVMC. However, when patients were ranked in terciles by fasting insulin level and within each tercile by subscapular skinfold thickness or weight tercile, increasing LVMC with increasing insulin level was found in the highest subscapular skinfold thickness and weight terciles. The largest difference was between high and low insulin groups (P </=.03). When grouped by systolic blood pressure tercile, there was no difference in LVMC with increasing fasting insulin tercile. We concluded that in heavier individuals, increased insulin levels may be a risk factor for the accumulation of increased LVMC independent of any relation among insulin, obesity, and blood pressure.

Relation between visceral fat and disease risk in children and adolescents

This review examines whether the relations and metabolic parameters necessary for the development of syndrome X are present in children and whether the metabolic complications of obesity in children are explained by excess intraabdominal adipose tissue (IAAT), or visceral fat. Despite the limited use of imaging techniques in research studies, an increasing number of studies reported on IAAT and its relation to disease risk in children and adolescents. For this article we reviewed studies that documented the early accumulation of IAAT in children and adolescents and the factors that contribute to variation in the degree of IAAT accumulation. We also reviewed studies that showed the clinical relevance of IAAT in children and adolescents through significant relations with adverse health effects including dyslipidemia and glucose intolerance in obese and nonobese children and adolescents of different ethnic groups.

Effects of strength training on intra-abdominal adipose tissue in obese prepubertal girls

PURPOSE

The purpose of this study was to determine the effects of strength training on fat distribution and its relationship to glucose tolerance in obese prepubertal girls.

METHODS

A strength training intervention study was designed in which the children exercised three times per week for 5 months. Twelve healthy, obese prepubertal girls (ages 7-10 yr, > 95th percentile weight for height) were enrolled in the study. Body composition was measured by dual-energy x-ray absorptiometry and computed tomography, and glucose tolerance was measured by a 3-h oral glucose tolerance test at baseline and after training.

RESULTS

Significant increases in height, weight, fat-free mass, fat mass, and subcutaneous abdominal adipose tissue occurred after training (P < 0.05), whereas intra-abdominal adipose tissue (IAAT) remained stable (N = 11). Insulin area was highly correlated with IAAT before (r = 0.91) and after (r = 0.90) training (both P < 0.01, N = 9).

CONCLUSION

In growing obese prepubertal girls undergoing a strength training program, IAAT remains unchanged, whereas subcutaneous abdominal fat and total body fat increased; insulin area is related to IAAT in these children.

Diet-induced insulin resistance precedes other aspects of the metabolic syndrome

This study was designed to examine the effects of a high-fat refined-sugar (HFS) or a low-fat complex-carbohydrate (LFCC) diet on insulin-stimulated skeletal muscle glucose transport, plasma insulin, blood pressure, plasma triglycerides, plasma glycerol, body weight, and body fat in female Fischer rats. Insulin-stimulated glucose transport was significantly reduced in the HFS group at 2 wk, 2 mo, and 2 yr, whereas serum insulin was significantly elevated at all time points. Blood pressure was not significantly elevated in the HFS group until 12 mo, and all HFS animals were hypertensive by 18 mo. Glycerol, triglycerides, and abdominal fat cell size were not significantly different at 2 wk but were significantly elevated in the HFS rats at 2 and 6 mo. Body weight was similar in both groups until 20 wk on the diet, when the HFS rats started to gain more weight. These results demonstrate that insulin resistance and hyperinsulinemia occur before the other manifestations of the metabolic syndrome and that diet, not obesity, is the underlying cause.

Age-related changes in cardiovascular disease risk factors of hypercholesterolemic children

OBJECTIVE

To describe the age-related changes in cardiovascular disease risk factors in young, hypercholesterolemic (HC) children.

METHODS

Hypercholesterolemic (n = 227) and nonhypercholesterolemic (NHC) (n = 80) children between the ages of 4 and 10 years were identified. Height, weight, skin-fold and blood pressure measurements, and total cholesterol levels were measured. The HC group also had insulin levels evaluated. The groups were compared by analysis of variance. Simple Spearman correlations evaluated the associations between factors within each group.

RESULTS

The HC and NHC groups had similar mean ages, heights, and weights, both contained 51% girls, and all were white subjects. Percent weight-for-height median, and biceps, triceps, suprailiac and subscapular skin-fold measurements were all larger for the HC group. A significant age interaction demonstrated that the HC group's larger suprailiac and sum of skin-fold measures were expressed in the 8.0- to 9.9-year-old children, but not the 4.0- to 5.9-year-olds. For both groups, systolic blood pressure was associated with the measures of adiposity. For the HC group, insulin levels were also associated with adiposity.

CONCLUSIONS

These results suggest that: (1) children with HC have greater body fat, (2) the expression of the hypercholesterolemia precedes the expression of increased body fat, (3) body fat increases with age, and (4) altered insulin and blood pressure levels are expressed in association with the increased body fat in children with HC. Confirmation with longitudinal data is necessary.

Childhood weight affects adult morbidity and mortality

Few studies have examined the long-term effects of childhood obesity on adult disease. Nonetheless, obesity present in childhood or adolescence seems to increase the likelihood of adult morbidity and mortality. In men who were obese during adolescence, all-cause mortality and mortality from cardiovascular disease and colon cancer were increased. In both men and women obese during adolescence, rates of cardiovascular disease and diabetes were increased. Among women but not men obese during adolescence, obesity has a variety of adverse psychosocial consequences. These include completion of fewer years of education, higher rates of poverty, and lower rates of marriage and household income. These effects seem related both to the persistence of obesity and to the effects of childhood or adolescent obesity on the quantity and location of body fat deposition. Approximately 50% of obese adolescents with a body mass index at or above the 95th percentile become obese adults. Furthermore, the risk factors for adult disease that are associated with obesity in children and adolescents persist into adulthood or increase in prevalence if weight gain occurs. Although both total body fat and regional fat deposition could account for the association of childhood or adolescent obesity with adult disease, no studies to date have examined cardiovascular risk factors and related them to visceral fat, controlled for total body fat.

Fat distribution in relation to sex and socioeconomic status in children 4-19 years

Fat distribution was studied in an urban sample of boys and girls 4.5 to 19.5 years from the Basque province of Biscay by means of Principal Component Analysis (PCA) of five skinfolds. The PCA extracted four components, which explained 99.1% of the total variance. The first principal component revealed strong stability across age and sex, and was related to a pattern of central body fat distribution. The three other components, upper-lower trunk fat, lateral-medial trunk fat, and upper-lower extremity fat, showed poor stability due largely to the influence of age and, to a lesser degree, sex. In both sexes, individual scores of the four factors did not show multivariate differences by socioeconomic status when a MANOVA with age, age² and age³ as covariates was done. Nevertheless, the first factor scores were significantly higher only in the poorer socioeconomic group of girls. The results are explained in the context of either different lifestyles related to socioeconomic status, a protective effect against environmental stress on urban males, or greater plasticity of trunk fat relative to extremity fat in females. Am. J. Hum. Biol. 10:799-806, 1998. © 1998 Wiley-Liss, Inc.

Increasing prevalence of overweight among US low-income preschool children: the Centers for Disease Control and Prevention pediatric nutrition surveillance, 1983 to 1995

OBJECTIVE

To determine whether the prevalence of overweight in preschool children has increased among the US low-income population.

DESIGN

Analysis using weight-for-height percentiles of surveillance data adjusted for age, sex, and race or ethnicity.

SETTING

Data from 18 states and the District of Columbia were examined.

SUBJECTS

Low-income children <5 years of age who were included in the Centers for Disease Control and Prevention Pediatric Nutrition Surveillance System.

RESULTS

The prevalence of overweight increased from 18.6% in 1983 to 21.6% in 1995 based on the 85th percentile cutoff point for weight-for-height, and from 8.5% to 10.2% for the same period based on the 95th percentile cutoff point. Analyses by single age, sex, and race or ethnic group (non-Hispanic white, non-Hispanic black, and Hispanic) all showed increases in the prevalence of overweight, although changes are greatest for older preschool children.

CONCLUSION

Overweight is an increasing public health problem among preschool children in the US low-income population. Additional research is needed to explore the cause of the trend observed and to find effective strategies for overweight prevention beginning in the preschool years.

Energy expenditure, body composition, and disease risk in children and adolescents

Recent methodological advances have led to a tremendous improvement in our ability to measure energy expenditure, body composition and fat distribution in children. The availability of new and improved measurement techniques has greatly enhanced the scope of research studies in children. The key findings from the present review are as follows: total energy expenditure in young children is approximately 25% lower than current recommendations for energy intake and revised recommendations are necessary; reduced energy expenditure, however, does not necessarily explain the greater prevalence of obesity in the population as a whole or in sub-groups at greater risk of obesity; qualitative aspects of physical activity (e.g. time, intensity) may be more important than the energy expenditure of physical activity in the regulation of body composition; for body composition assessment, DXA is emerging as a technique which can substantially improve the accuracy and standardization in children; body fat begins to accumulate in the obese; waist:hip ratio or waist circumference are inadequate markers of intra-abdominal adipose tissue in children and adolescents; finally, the early accumulation of fat in the intra-abdominal region is significantly related to the development of adverse health effects, including dyslipidaemia and glucose intolerance.