Relation between visceral fat and disease risk in children and adolescents

10: Management of obesity

Obesity has reached epidemic proportions in Australia, with 67.5% of men, 52.1% of women and 19%-23% of children and adolescents being overweight or obese. Genetically predisposed individuals are especially vulnerable to developing obesity in the highly obesogenic environment of 21st century Australia. Obesity causes or contributes to many comorbidities, including type 2 diabetes, hypertension, dyslipidaemia, sleep apnoea, non-alcoholic steatohepatitis, orthopaedic problems and polycystic ovary syndrome. Management in the individual requires their complete co-operation and should be tailored to individual needs and complications. Management of obesity in children should consider the family context and involve the parents. All treatment strategies must involve lifestyle modification, with a reduction of energy intake and an increase in physical activity. Some patients may also require the assistance of drug therapy or bariatric surgery.

Effects of a multidisciplinary weight loss intervention on body composition in obese adolescents

OBJECTIVE

To investigate if a multidisciplinary weight loss program in adolescents suffering severe obesity allows adequate growth and development and avoid lean mass loss.

DESIGN

A total of 55 adolescents (33 girls and 22 boys) suffering severe obesity were enrolled in an interdisciplinary weight reduction program lasting 6-12 months. Progressive submaximal physical activity was performed and national dietary allowances for adolescents with low levels of physical activity energy were provided.

MEASUREMENTS

Total and segmental body composition was assessed by means of dual-energy X-ray absorptiometry.

RESULTS

The mean height significantly increased (P<0.001). The mean body mass index (BMI) dropped in boys from 34.5+/-3.2 to 25.5+/-2.3 kg/m(2) and in girls from 38.4+/-4.1 to 28.4+/-4.1 kg/m(2). Height increased according to the expected pattern (P<0.001). Total lean mass (LM) did not vary and was positively correlated to pubertal development in both sexes before and after weight loss. Steepest drop in fat mass (FM) was observed in the trunk (-63.2+/-10.1% in boys and -51.5+/-11.4% in girls). Decrease in BMI and FM was tightly correlated in both sexes. However, slopes significantly differed (P<0.0005) so that a decrease of 1 kg/m(2) in BMI corresponded to a decrease of 3.92 kg in FM in girls and of 5.44 kg in boys. In each sex, FM at baseline and duration of the treatment were the main determinants of the decrease in FM.

CONCLUSION

During adolescence, despite a major weight loss, adequate growth and preservation of LM can be achieved. Weight loss kinetics markedly differs between boys and girls. Low-calorie diets are unnecessary to achieve a marked reduction of severe obesity during puberty.

Using a phantom to compare MR techniques for determining the ratio of intraabdominal to subcutaneous adipose tissue

OBJECTIVE

Patients who have a greater distribution of intraabdominal adipose tissue as compared with subcutaneous adipose tissue and an increased ratio of intraabdominal adipose tissue to subcutaneous adipose tissue are at greater risk for developing cardiovascular disease and type 2 diabetes mellitus. In previous MR investigations, researchers have used conventional T1-weighted spin-echo images to determine the ratio of intraabdominal adipose tissue to subcutaneous adipose tissue. However, no investigation, to our knowledge, has been performed to determine the accuracy of using different MR sequences to estimate adipose distribution. The purpose of our investigation was to compare MR imaging and segmentation techniques in calculating the ratio of intraabdominal to subcutaneous adipose tissue using an adiposity phantom.

MATERIALS AND METHODS

A phantom was created to simulate the distribution of subcutaneous and intraabdominal fat (with known volumes). Axial MR images were obtained twice through the phantom using a 5-mm slice thickness and zero gap for the following T1-weighted sequences: spin-echo, fast Dixon, and three-dimensional (3D) spoiled gradient-echo. An in-house computer software program was then used to segment the volumes of fat and calculate the volume of intraabdominal adipose tissue and subcutaneous adipose tissue and the ratio of intraabdominal to subcutaneous adipose tissue. Each imaging data set was segmented three times, so six sets of data were yielded for each imaging technique. The percentage predicted of the true volume was calculated for each MR imaging technique for each fat variable. The mean percentages for each variable were then compared using one-factor analysis of variance to determine whether differences exist among the three MR techniques.

RESULTS

The three MR imaging techniques had statistically significant different means for the predicted true volume of two variables: volume of subcutaneous adipose tissue (p < 0.001) and volume of intraabdominal adipose tissue (p = 0.0426). Estimates based on fast Dixon images were closest to the true volumes for all the variables. All MR imaging techniques performed similarly in estimating the ratio of intraabdominal adipose tissue to subcutaneous adipose tissue (p = 0.9117). The acquisition time for the 3D spoiled gradient-echo images was 10-22 times faster than for the other sequences.

CONCLUSION

Conventional T1-weighted spin-echo MR imaging, the current sequence used in practice for measuring visceral adiposity, may not be the optimal MR sequence for this purpose. We found that the T1-weighted fast Dixon sequence was the most accurate at estimating all fat volumes. The T1-weighted 3D spoiled gradient-echo sequence generated similar ratios of intraabdominal to subcutaneous adipose tissue in a fraction of the acquisition time.

Childhood obesity in Canada: a review of prevalence estimates and risk factors for cardiovascular diseases and type 2 diabetes

Childhood obesity in Canada has become increasingly prevalent over the past 2 decades. Despite inconsistencies regarding different anthropometric indicators, cut-offs, and reference populations, both regional and national investigations have revealed high numbers of overweight and obese children and adolescents. A number of risk factors and health consequences have been associated with increased levels of body fatness in youth. Specifically, risk factors for cardiovascular diseases (CVD) and type 2 diabetes are known to develop early in life and tend to emerge in clusters among overweight youngsters. Unhealthy lifestyle behaviours (i.e., physical inactivity), a genetic disposition, and a centralized body fat distribution, all contribute to increased risk. In order to prevent future generations of children from experiencing increased morbidity and mortality as overweight and obese adults, coordinated efforts at all levels (family, school, community, and government) must be established with a long-term commitment to promote healthy nutrition and physical activity behaviours in our youth.

Metabolic complications of antiretroviral therapy in children

Survival in HIV-infected children has greatly improved with the introduction of highly active antiretroviral therapy. Children are more vulnerable than adults to metabolic side effects of therapy because of its potential impact on growth and the children's likely greater cumulative exposure. This review summarizes the epidemiology and management of lipodystrophy, dyslipidemia, insulin resistance, hyperlactatemia, osteopenia and growth failure in HIV-infected children.

Body composition and metabolic factors in obese children and adolescents

OBJECTIVE

Body composition is associated with metablic factors in adults; however, data are limited regarding obese children. This study was undertaken to assess body composition, regional fat distribution, and metabolic factors in obese 6-18-y-old children and adolescents.

DESIGN

Cross-sectional assessment.

SUBJECTS

Thirty-six obese children and adolescents, (mean+/-s.e.m.) age 11.8+/-0.5 y, BMI 34.1+/-1.2 kg/m(2).

MEASUREMENTS

Body composition was assessed by dual energy X-ray absorptiometry and computerized tomography. Fasting insulin, glucose and leptin levels, and the homeostasis model assessment of insulin sensitivity (HOMA-IR) were assessed.

RESULTS

The girls had significantly lower glucose levels than the boys. The ethnic group differences (African American children vs white children) in fat mass, total CT fat, subcutaneous CT fat, insulin level, leptin level, and higher HOMA-IR were not significant after adjusting for age or pubertal stage. These differences in abdominal fat and subcutaneous abdominal fat were also not independent of total body fat or BMI. No ethnic group differences in visceral abdominal fat were noted. Insulin level and HOMA IR were associated with leptin level (independent of fat mass) and fat mass. Leptin level was associated with fat mass, total CT fat, and subcutaneous CT fat; however the associations between the CT fat measures and leptin were not independent of total body fat mass.

CONCLUSIONS

Neither visceral abdominal fat, subcutaneous abdominal fat, insulin levels, or insulin resistance differed by ethnic group when adjusted for age or pubertal status. This contrasts with findings in adults and non-obese children which suggest lower levels of visceral fat and higher insulin levels and insulin resistance in African American children and adolescents.

Unique effect of visceral fat on insulin sensitivity in obese Hispanic children with a family history of type 2 diabetes

OBJECTIVE

This study aimed to establish whether total fat or central fat was related to measures of insulin in obese Hispanic children with a family history of type 2 diabetes.

RESEARCH DESIGN AND METHODS

Subjects were 32 children aged 8-13 years. Visceral fat and subcutaneous abdominal fat were determined by magnetic resonance imaging at the umbilicus and total body fat was determined by dual-energy X-ray absorptiometry. Insulin sensitivity (S(i)) and acute insulin response (AIR) were determined by frequently sampled intravenous tolerance test with minimal modeling.

RESULTS

Mean fasting glucose and insulin, S(i), and AIR (+/- SD) were 5.3 +/- 0.3 mmol/l, 206 +/- 105 pmol/l, 11.8 +/- 5.7 [x 10(-4) min(-1)/(pmol/l)], and 17,175 +/- 9,695 (pmol/l x 10 min), respectively. In multivariate regression analysis, total fat mass was independently and positively related to fasting insulin (P < 0.01) and negatively related to S(i) (P < 0.05) but was not related to AIR. Visceral fat was independently and positively related to fasting insulin (P < 0.05) and AIR (P < 0.01) and negatively related to S(i) (P < 0.001).

CONCLUSIONS

-These findings support the hypothesis that specific accumulation of visceral fat in addition to overall adiposity in Hispanic children increases the risk of type 2 diabetes.

Upper abdominal obesity, insulin resistance and breast cancer risk

PURPOSE

A majority of prospective studies show breast cancer risk to be higher in obese postmenopausal women with upper abdominal adiposity than in those with overall adiposity. The evidence is more limited and inconsistent in the case of premenopausal women. The review examines evidence that aberrant insulin signalling may be involved in the promotion of mammary carcinogenesis. The aetiology and concomitants of abdominal visceral obesity are examined.

MECHANISMS

Clinical and experimental evidence suggests that the higher breast cancer risk associated with greater abdominal visceral obesity may be related to aberrant insulin signalling through the insulin receptor substrate 1 pathway, leading to insulin resistance, hyperinsulinaemia and increased concentrations of endogenous oestrogen and androgen. The putative role of aberrant insulin signalling in the promotion of mammary carcinogenesis may help to explain clinical relationships between breast cancer risk and age at menarche, pregnancies and onset of obesity.

CONCLUSION

Overall adiposity in women adversely affects breast cancer risk mainly by greater exposure of mammary epithelial tissue to endogenous oestrogen. Upper abdominal adiposity appears to involve an additional effect related to the presence of insulin resistance. Aetiological factors in the development of hyperinsulinaemic insulin resistance are still uncertain but may involve aberrant susceptibility genes in adipocyte insulin receptors or in the insulin receptor substrate 1 pathway. Epigenetic factors are also likely to contribute, including high free fatty acid levels and obesity. Dietary fatty acids, particularly polyunsaturated fatty acids, are known to regulate adipocyte differentiation through the nuclear peroxisome proliferator-activated receptor gamma, and may also have a role in insulin resistance. These aetiological factors are likely to be relevant to the high risk of postmenopausal breast cancer in industrialised Western populations.

Effects of low birth weight on insulin resistance syndrome in caucasian and African-American children

OBJECTIVE

To examine the effects of low birth weight (LBW) on the components of insulin resistance syndrome (IRS) in Caucasian and African-American children aged 4-14 years (n = 560 observations among 139 subjects).

RESEARCH DESIGN AND METHODS

A linear random-effects modeling analysis with repeated measures (average four annual visits per child) was conducted to examine the associations between LBW and the components of IRS and their developmental trends over age. Fasting glucose, insulin, and lipids were assessed after an overnight fast; insulin action and secretion were determined by the tolbutamide-modified frequently sampled intravenous glucose tolerance test; and body composition was assessed by dual energy X-ray absorptiometry and computed tomography.

RESULTS

LBW was significantly associated with increased fasting insulin concentration and visceral fat mass, decreased acute insulin response, beta-cell function, and HDL cholesterol among African-American children. Among children with LBW, there were significant differences in fasting insulin, insulin sensitivity, acute insulin response, and HDL cholesterol between Caucasians and African-Americans. LBW was significantly associated with faster decrease in acute insulin response and increase in triglycerides with regard to age. The hyperbolic function between insulin sensitivity and beta-cell function was retarded among children with LBW (P = 0.04). In addition, there was a significant interaction between LBW and ethnicity in relation to fasting insulin (P < 0.05) and visceral fat (P = 0.05).

CONCLUSIONS

LBW may predict the risk of the IRS and its progression over age in childhood, and this effect may be more pronounced among African-American children.

Tracking body fat distribution during growth: using measurements at two occasions vs one

OBJECTIVE

To investigate whether within-individual variation is a factor in the generally reported poor tracking of central body fat distribution (CBFD) during development and whether two measurements of CBFD during each measurement occasion would improve the estimate of tracking over time.

METHODS

A longitudinal study compared the results of two measurements of body fat (BF) and CBFD during each measurement occasion to the results of one measurement of BF and CBFD during each occasion every 4 months over 1-3 y. A total of 345 boys and 333 girls in three age cohorts of 8, 11 and 14 y at baseline were examined. BF variables were: body mass index (BMI); fat mass and percentage body fat from bioelectrical impedance; two skinfold sums; and abdominal circumference. CBFD variables were: waist/hip and waist/thigh ratios; conicity; and log upper-lower skinfold ratio.

RESULTS

Three-year tracking of BF varied from 0.79 to 0.90 for one- and from 0.81 to 0.93 for two-occasion measurements showing no apparent sex- or cohort-effects. Three-year tracking of CBFD was lower than that of BF (0.68-0.75), but improved significantly with two-occasion measurements (0.75-0.82).

CONCLUSIONS

Within-individual variation is a significant factor in reported low tracking of CBFD in childhood. Estimates of tracking currently in the literature may underestimate the predictive value of CBFD, possibly because this research has used one-occasion measurement. The increased use of two-occasion measurement should significantly improve the tracking of CBFD during development and provide a more realistic understanding of its predictive value.

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.

The development of waist circumference percentiles in British children aged 5.0-16.9 y

OBJECTIVE

To develop waist circumference percentile curves for British children and to compare these curves with those from other countries.

DESIGN

Cross-sectional study.

SETTING

School-aged population.

SUBJECTS

A representative sample of school children from the geographical regions of Great Britain, approximately in proportion to their age distribution. The sample population consisted of 8355 children (3585 males, 4770 females) with ages ranging between 5.0 and 16.9 y.

INTERVENTIONS

Waist circumferences were measured with a flexible non-elastic tape and waist circumference percentiles were constructed and smoothed using the LMS method.

MAIN OUTCOME MEASURES

Smoothed waist circumference percentile curves.

RESULTS

Mean waist circumference increased with age in both boys and girls. For girls, curves began to plateau after the age of 13 y whereas, for boys, waist percentile curves continued to increase more sharply after this age. However, these curves mainly reflect the patterns of waist circumference in Caucasian children.

CONCLUSIONS

These curves represent the first waist circumference percentiles for British children and could be used provisionally for both clinical and possibly epidemiological use, although they should be validated against equivalent longitudinal data.

SPONSORSHIP

This project has been sponsored by UNL Diversity and Development Fund.

Total and regional fat and serum cardiovascular disease risk factors in lean and obese children and adolescents

OBJECTIVE

This study was conducted to evaluate the association of total and central adiposity with serum cardiovascular disease (CVD) risk factors in lean and obese Portuguese children and adolescents.

RESEARCH METHODS AND PROCEDURES

A total of 87 girls (13.2 +/- 1.6 years old, 29.9 +/- 6.4% body fat [mean +/- SD]) and 72 boys (13.2 +/- 1.6 years old, 20.8 +/- 9.9% body fat) volunteered for the study. Whole-body composition and fat distribution, from DXA and anthropometry, and serum lipids, lipoproteins, and apolipoproteins were evaluated.

RESULTS

The sum of three trunk skinfolds (STS) was highly correlated with total trunk fat mass measured by DXA (p < 0.001). Body mass index, DXA-measured percentage of body fat, trunk fat mass, STS, and the waist-to-height ratio were generally found to be associated with triacylglycerol, the ratio of total cholesterol (TC) to high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), and apolipoprotein B levels, (significant age-adjusted r between 0.16 and 0.27, p < 0.05). Body mass index, STS, and the waist circumference were also associated with HDL-C (p < 0.05), whereas no body composition variable significantly correlated with TC or apolipoproteins A-I. The STS was significantly correlated with HDL-C (p < 0.01), TC/HDL-C (p < 0.05), and apolipoproteins A-I (p < 0.05) independently of whole-body fatness. Obese subjects (n = 73) had higher TC, LDL-C, TC/HDL-C, and apolipoprotein B than did non-obese subjects (n = 86), and significant associations between central adiposity and some lipid variables (triacylglycerol and HDL-C) were found in obese children and adolescents that were not present in leaner individuals.

DISCUSSION

DXA- and anthropometry-based whole-body and central fat measures are associated with serum CVD risk factors in Portuguese boys and girls. Obese children and adolescents have a poorer lipid profile than do their leaner counterparts. Trunk skinfolds, which are easy to obtain even in large samples, predict CVD risk factors to the same extent as DXA-based variables, in some cases, independently of total fatness.

Serum lipids, serum insulin, plasma fibrinogen and aerobic capacity in obese and non-obese Singaporean boys

OBJECTIVES

To compare blood lipids, lipoproteins, apoproteins, fibrinogen, insulin and aerobic capacity in obese and non-obese Chinese Singaporean boys. To examine relationships between blood metabolites, body composition and aerobic capacity in these groups.

DESIGN

Cross-sectional.

SUBJECTS

Forty Chinese Singaporean boys aged 13-15 y. Classified as obese (n=20) or non-obese (n=20) based on adiposity (fat mass/fat free mass): >0.60=obese, <0.40=non-obese.

MEASUREMENTS

Body composition (dual energy X-ray absorptiometry), waist circumference, peak oxygen consumption (VO(2) peak), serum concentrations of total cholesterol, triacylglycerol, high density lipoprotein cholesterol (HDL-C), total cholesterol/HDL-C, apoproteins AI and B, lipoprotein(a), insulin and glucose. Plasma concentration of fibrinogen.

RESULTS

Obese boys had significantly (P<0.01) higher (mean+/-s.d.) concentrations of serum triacylglycerol (1.51+/-0.65 vs 1.04+/-0.34 mmol/l), serum insulin (24.1+/-11.5 vs 12.3+/-4.45 mU/l) and plasma fibrinogen (4.01+/-0.54 vs 3.35+/-0.76 g/l) than non-obese boys. Within the non-obese group plasma fibrinogen concentration was significantly related to percentage body fat (r=0.546, P<0.05). VO(2) peak relative to body mass (ml/kg/min or ml/kg(-0.67)/min) was significantly (P<0.001) lower in obese compared to non-obese boys but absolute VO(2) peak (l/min), adjusted for fat-free mass via analysis of covariance, was higher in obese than non-obese boys (P<0.01). Partial correlations revealed that none of the blood metabolites were significantly related to VO(2) peak independent of body fatness.

CONCLUSIONS

Obesity was related to elevated concentrations of serum triacylglycerol, serum insulin and plasma fibrinogen in Chinese Singaporean boys. These elevated concentrations did not appear to be associated with a lower aerobic capacity (independent of body fatness) in the obese.

Does waist circumference predict fat gain in children?

OBJECTIVE

The aim of this study was to identify in a group of 8-y-old prepubertal children the anthropometric parameter with the highest prediction power of overweight, measured 4 y later.

SUBJECTS

One-hundred and twelve Caucasian children (54 males, 58 females), aged 8.7+/-0.9 y, were studied.

RESULTS

An analysis of the association between relative body mass index (BMI) at follow-up (%) and some indexes of adiposity like relative BMI (%), waist circumference, subscapular and triceps skinfolds, the sum of four skinfolds and percentage fat mass measured at baseline, showed that relative BMI (relBMI) at baseline had the highest association with relBMI at follow-up (r=0.77; P<0.001); waist circumference had a slightly lower significant association with relBMI at follow-up (r=0.74; P<0.001). In a multiple regression analysis, waist circumference (adjusted for age) accounted for approximately 64% of the variation of relBMI at follow-up (P<0.001). RelBMI measured at baseline accounted for approximately 59% of the variation of relBMI at follow-up (P<0.001). Multiple logistic regression analysis included waist circumference, adjusted for age, mother's BMI and relBMI measured at baseline as independent variables in the final equation. In particular, each centimeter increase of waist circumference at the age of 8 y doubled the risk of having a relBMI greater than 120% at the age of 12 y.

CONCLUSION

The results of this study, the first which has approached this investigation in children, showed that waist circumference measured at the age of 8 y, which is simple to perform and easy to reproduce, may be a promising index to assess adiposity as well as to predict overweight at puberty.

Lipodystrophy in HIV-infected children is associated with high viral load and low CD4+ -lymphocyte count and CD4+ -lymphocyte percentage at baseline and use of protease inhibitors and stavudine

Alterations in regional fat, often associated with abnormalities in lipid and insulin metabolism, have been reported in HIV-infected adults. To determine whether similar abnormalities occur in children with HIV, patterns of change in regional body fat distribution were determined by dual energy x-ray absorptiometry in 28 prepubertal HIV-infected children. Eight (29%) children experienced lipodystrophy (LD), defined as extremity lipoatrophy together with trunk fat accumulation. Despite a mean body weight increase of 2.9 +/- 2.4 kg, children with LD experienced a mean loss of total fat in contrast to children without LD who increased total fat (-0.151 +/- 0.324 versus 0.981 +/- 1.041 kg; p <.01). Children with LD had significantly higher levels of HIV RNA and lower CD4 count and percentage at baseline. LD was associated with use of protease inhibitors or stavudine, (odds ratio [OR], 7.0, 95% confidence interval [CI], 1.1-45.2, p =.04; OR, 9.0, 95% CI, 1.4-59.8, p =.03, respectively). This observational study suggests that during a time in childhood when accumulation of extremity and trunk fat is expected, some HIV-infected children experience changes in fat distribution that are similar to HIV-associated LD reported in adults. Studies to determine whether HIV-infected children with changes in regional fat also experience increases in "atherogenic" lipids and insulin resistance as described in adults with HIV-associated LD are warranted.

The effect of protease inhibitor therapy on growth and body composition in human immunodeficiency virus type 1-infected children

OBJECTIVE

To determine the effect of protease inhibitors (PIs) on growth and body composition in children with human immunodeficiency virus type 1 (HIV-1) infection.

BACKGROUND

HIV-1-infected children have chronic problems with both linear growth and weight gain. Viral load may directly influence growth and nutritional status of HIV-1-infected children with reduction of viral load improving the nutritional condition.

DESIGN/METHODS

Data from 67 patients who initiated PI therapy between 1996 and 1999 and who were enrolled in a prospective, longitudinal study of growth and nutrition in HIV-1-infected children were analyzed. Outcomes included pre-PI versus post-PI measures of height, weight, weight-for-height, triceps skinfold thickness, and arm muscle circumference. Predictor covariates included age, race, gender, Tanner stage, CD4 z score, Centers for Disease Control and Prevention stage, route of infection, plasma HIV-1 RNA, other antiretroviral therapy, recommended daily allowances for calories, treatment with megestrol acetate, and PI therapy.

RESULTS

Sixty-seven children were followed for a median of 2.4 years with a total of 362 visits (median: 5 visits; range: 1-12). During follow-up, they received PIs for a median of 5 months. Fifty-one percent were girls, 54% black, 15% Hispanic, and 25% white. The mean age at first visit was 6.8 years. In a univariate analysis, weight z score (-0.67 to -0.35) and weight/height z score (0.25-0.76) improved on PI therapy. Using repeated-measures regression analysis, controlling for the above named covariates, PI treatment showed a significant effect on weight z score (increase in z score by 0.46), weight/height z score (increase in z score by 0.49), and arm muscle circumference (increase in percentile by 11.5). A borderline effect was found for height z score (increase in z score by 0.17) and no effect was found for triceps skinfold thickness. In a separate analysis, PI therapy increased CD4 counts twofold and reduced plasma HIV-1 RNA copies by 79%.

CONCLUSION

In addition to a significant reduction in viral load, PI therapy in children has a positive effect on several growth parameters, including weight, weight/height, and muscle mass.

Waist circumference and cardiovascular risk factors in prepubertal children

OBJECTIVE

Intra-abdominal fat has been identified as being the most clinically relevant type of fat in humans. Therefore, an assessment of body-fat distribution could possibly identify subjects with the highest risk of adverse lipid profile and hypertension. Few data on the relationship between body-fat distribution and cardiovascular risk factors are available in children, especially before puberty.

RESEARCH METHODS AND PROCEDURES

This cross-sectional study was undertaken to explore the relationship between anthropometric variables, lipid concentrations, and blood pressure (BP) in a sample of 818 prepubertal children (ages 3 to 11 years) and to assess the clinical relevance of waist circumference in identifying prepubertal children with higher cardiovascular risk. Height, weight, triceps and subscapular skinfolds, waist circumference, and BP were measured. Plasma levels for triacylglycerol, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein cholesterol, apolipoprotein A1 (ApoA1), and apolipoprotein B (ApoB) were determined.

RESULTS

Females were fatter than males (5.8 [3.5] vs. 4.8 [3.3] kg of fat mass; p < 0.01). Males had higher HDL cholesterol and ApoA1/ApoB plasma concentrations than females (p < 0.001 and p < 0.01, respectively). Waist circumference had a higher correlation with systolic and diastolic BP (r = 0.40 and 0.29, respectively; p < 0.001) than triceps (r = 0.35 and 0.21, respectively; p < 0.001) and subscapular (r = 0.28 and 0.16, respectively; p < 0.001) skinfolds and relative body weight (0.33 and 0.23, respectively; p < 0.001). Multivariate linear model analysis showed that ApoA1/ApoB, HDL cholesterol, total cholesterol/HDL cholesterol, and systolic as well as diastolic BP were significantly associated with waist circumference and triceps and subscapular skinfolds, independently of age, gender, and body mass index.

DISCUSSION

Waist circumference as well as subscapular and triceps skinfolds may be helpful parameters in identifying prepubertal children with an adverse blood-lipids profile and hypertension. However, waist circumference, which is easy to measure and more easily reproducible than skinfolds, may be considered in clinical practice. Children with a waist circumference greater than the 90th percentile are more likely to have multiple risk factors than children with a waist circumference that is less than or equal to the 90th percentile.

Evaluation of waist circumference, waist-to-hip ratio, and the conicity index as screening tools for high trunk fat mass, as measured by dual-energy X-ray absorptiometry, in children aged 3-19 y

BACKGROUND

A central fat pattern has adverse health implications in both children and adults. Because adiposity tracks from childhood into adulthood, the ability of simple anthropometric techniques to correctly measure truncal adiposity in childhood needs to be assessed.

OBJECTIVES

We sought to assess the validity of waist circumference, waist-to-hip ratio (WHR), and the conicity index as indicators of trunk fat mass in children and adolescents.

DESIGN

Trunk fat mass (kg) was measured with dual-energy X-ray absorptiometry in 278 girls and 302 boys aged 3-19 y. Receiver operating characteristic (ROC) curves and areas under the curves (AUCs) for the ROCs were calculated to compare the relative abilities of the anthropometric measures to correctly identify children with high trunk fat mass (z score for our study population of > or =1).

RESULTS

The 80th percentile for waist circumference correctly identified 89% of girls and 87% of boys with high trunk fat mass (sensitivity) and 94% of girls and 92% of boys with low trunk fat mass (specificity). Waist circumference performed significantly better as an index of trunk fat mass than did WHR or the conicity index, as shown by the AUCs in girls and boys, respectively: waist circumference AUCs = 0.97 and 0.97, conicity index AUCs = 0.80 and 0.81, and WHR AUCs = 0.73 and 0.71. Our cutoffs for high trunk fat mass and high waist circumference are provided for both sexes for each year of age.

CONCLUSION

Waist circumference provides a simple yet effective measure of truncal adiposity in children and adolescents.

Nutrition interventions in childhood for the prevention of chronic diseases in adulthood

As it becomes increasingly evident that the seeds of many adult disorders are planted in childhood, it is important that pediatric care providers 1) recognize risk factors for adult disease in children and 2) institute effective interventions. Many adult medical conditions are significantly related to or influenced by nutritional factors. This review evaluates three areas in preventive and therapeutic pediatric nutrition: obesity, lipid disorders, and osteoporosis.