Body composition in prepubertal girls: comparison of six methods

Gestational Weight Gain Relates to DNA Methylation in Umbilical Cord, Which, In Turn, Associates with Offspring Obesity-Related Parameters

Excessive gestational weight gain (GWG) has a negative impact on offspring's health. Epigenetic modifications mediate these associations by causing changes in gene expression. We studied the association between GWG and DNA methylation in umbilical cord tissue; and determined whether the DNA methylation and the expression of corresponding annotated genes were associated with obesity-related parameters in offspring at 6 years of age. The methylated CpG sites (CpGs) associated with GWG were identified in umbilical cord tissue by genome-wide DNA methylation (n = 24). Twelve top CpGs were validated in a wider sample by pyrosequencing (n = 87), and the expression of their 5 annotated genes (SETD8, TMEM214, SLIT3, RPTOR, and HOXC8) was assessed by RT-PCR. Pyrosequencing results validated the association of SETD8, SLIT3, and RPTOR methylation with GWG and showed that higher levels of SETD8 and RPTOR methylation and lower levels of SLIT3 methylation relate to a higher risk of obesity in the offspring. The association of SETD8 and SLIT3 gene expression with offspring outcomes paralleled the association of methylation levels in opposite directions. Epigenetic changes in the umbilical cord tissue could explain, in part, the relationship between GWG and offspring obesity risk and be early biomarkers for the prevention of overweight and obesity in childhood.

Equations based on anthropometric measurements for adipose tissue, body fat, or body density prediction in children and adolescents: a scoping review

PURPOSE

Assessing the body composition of children and adolescents is important to monitor their health status. Anthropometric measurements are feasible and less-expensive than other techniques for body composition assessment. This study aimed to systematically map anthropometric equations to predict adipose tissue, body fat, or density in children and adolescents, and to analyze methodological aspects of the development of anthropometric equations using skinfolds.

METHODS

A scoping review was carried out following the PRISMA-ScR criteria. The search was carried out in eight databases. The methodological structure protocol of this scoping review was retrospectively registered in the Open Science Framework ( https://osf.io/35uhc/ ).

RESULTS

We included 78 reports and 593 anthropometric equations. The samples consisted of healthy individuals, people with different diseases or disabilities, and athletes from different sports. Dual-energy X-ray absorptiometry (DXA) was the reference method most commonly used in developing equations. Triceps and subscapular skinfolds were the anthropometric measurements most frequently used as predictors in the equations. Age, stage of sexual maturation, and peak height velocity were used as complementary variables in the equations.

CONCLUSION

Our scoping review identified equations proposed for children and adolescents with a great diversity of characteristics. In many of the reports, important methodological aspects were not addressed, a factor that may be associated with equation bias.

LEVEL IV

Evidence obtained from multiple time series analysis such as case studies. (NB: dramatic results in uncontrolled trials might also be regarded as this type of evidence).

Methylation of the C19MC microRNA locus in the placenta: association with maternal and chilhood body size

OBJECTIVES

To study DNA methylation at the C19MC locus in the placenta and its association with (1) parental body size, (2) transmission of haplotypes for the C19MC rs55765443 SNP, and (3) offspring's body size and/or body composition at birth and in childhood.

SUBJECTS AND METHODS

Seventy-two pregnant women-infant pairs and 63 fathers were included in the study. Weight and height of mothers, fathers and newborns were registered during pregnancy or at birth (n = 72). Placental DNA methylation at the C19MC imprinting control region (ICR) was quantified by bisulfite pyrosequencing. Genotyping of the SNP was performed using restriction fragment length polymorphisms. The children's body size and composition were reassessed at age 6 years (n = 32).

RESULTS

Lower levels of placental C19MC methylation were associated with increased body size of mother, specifically with higher pregestational and predelivery weights and height of the mother (β from -0.294 to -0.371; R² from 0.04 to 0.10 and all p < 0.019), and with higher weight, height, waist and hip circumferences, and fat mass of the child (β from -0.428 to -0.552; R² from 0.33 to 0.56 and all p < 0.009). Parental transmission of the SNP did not correlate with an altered placental methylation status at the C19MC ICR.

CONCLUSIONS

Increased maternal size is associated with reduced placental C19MC methylation, which, in turn, relate to larger body size of the child.

Neutrophil-to-lymphocyte ratio: an inflammation marker related to cardiovascular risk in children

Low-grade chronic inflammation plays a pathogenic role in cardiovascular disease. An increase in the ratio of circulating neutrophils to lymphocytes (N/L ratio) may serve as a marker of cardiovascular risk in adults. It was the study objective to study whether N/L ratio associates with vascular parameters in children. Subjects were 501 prepubertal and early pubertal Caucasian children (mean age 8.0 years; mean body mass index (BMI) Z-score 0.2 ± 0.9; 266 boys and 235 girls) recruited within an ongoing population-based study. The subjects were stratified into three groups according to age. Neutrophil, lymphocyte, BMI, waist circumference, systolic blood pressure (SBP) and carotid intima-media thickness (cIMT), assessed in all children. The N/L ratio, derived from the absolute neutrophil and lymphocyte counts. In children aged < 7 years (n=190, all prepubertal), no associations were observed between N/L ratio and either anthropometric or cardiovascular parameters. In children aged 7–9 years (n=171, 1.7 % early pubertal), higher N/L ratio associated with higher BMI Z-score and waist circumference (p=0.008 to p< 0.0001). In children aged > 9 years (n=140, 29.2 % early pubertal), N/L ratio associated again with BMI Z-score and waist circumference and also positively with SBP and cIMT (all p=0.008 to p< 0.0001). These associations remained significant in linear regression models following adjustment for possible confounding variables such as age, gender, fasting triglycerides, C-reactive protein and puberty (and for SBP and cIMT, adjustment also for BMI). In conclusion, our results provide the first evidence that a higher N/L ratio is associated with a less favourable cardiovascular profile in children and delineate the development of these associations from late childhood onwards.

Percentile reference values for anthropometric body composition indices in European children from the IDEFICS study

INTRODUCTION

To characterise the nutritional status in children with obesity or wasting conditions, European anthropometric reference values for body composition measures beyond the body mass index (BMI) are needed. Differentiated assessment of body composition in children has long been hampered by the lack of appropriate references.

OBJECTIVES

The aim of our study is to provide percentiles for body composition indices in normal weight European children, based on the IDEFICS cohort (Identification and prevention of Dietary- and lifestyle-induced health Effects in Children and infantS).

METHODS

Overall 18,745 2.0-10.9-year-old children from eight countries participated in the study. Children classified as overweight/obese or underweight according to IOTF (N=5915) were excluded from the analysis. Anthropometric measurements (BMI (N=12 830); triceps, subscapular, fat mass and fat mass index (N=11,845-11,901); biceps, suprailiac skinfolds, sum of skinfolds calculated from skinfold thicknesses (N=8129-8205), neck circumference (N=12,241); waist circumference and waist-to-height ratio (N=12,381)) were analysed stratified by sex and smoothed 1st, 3rd, 10th, 25th, 50th, 75th, 90th, 97th and 99th percentile curves were calculated using GAMLSS.

RESULTS

Percentile values of the most important anthropometric measures related to the degree of adiposity are depicted for European girls and boys. Age- and sex-specific differences were investigated for all measures. As an example, the 50th and 99th percentile values of waist circumference ranged from 50.7-59.2 cm and from 51.3-58.7 cm in 4.5- to <5.0-year-old girls and boys, respectively, to 60.6-74.5 cm in girls and to 59.9-76.7 cm in boys at the age of 10.5-10.9 years.

CONCLUSION

The presented percentile curves may aid a differentiated assessment of total and abdominal adiposity in European children.

Emotional psychopathology and increased adiposity: follow-up study in adolescents

Based on data from a three-year longitudinal study, we assess the effect, according to gender, of emotional psychopathology in preadolescence on anthropometric and body composition parameters in adolescence (N = 229). Psychopathology was assessed using the Screen for Childhood Anxiety and Related Emotional Disorders, the Children's Depression Inventory and the MINI-International Neuropsychiatric Interview for Kids. Body fat percentage (%BF), waist circumference (WC) and body mass index (BMI) were also determined. Following analysis with adjusted multiple regression models, the results indicated that symptoms of depression and separation anxiety were significantly associated with increased WC and BMI in boys, and that somatic symptoms were associated with increased WC and %BF in girls. Diagnosis of social phobia, panic disorder or dysthymia led to significantly increased WC and/or BMI in boys and dysthymia increased WC in girls. These findings suggest that emotional psychopathology in preadolescence is associated with increased weight gain and abdominal fat in adolescence.

Changes in skinfold thickness and body composition among children and adolescents in Shandong, China from 1995 to 2010

BACKGROUND

There is strong evidence of a upward secular trend in skinfold thickness (SFT) and the prevalence of obesity has increased substantially over recent decades in developed countries. However, no studies on this trend have been reported in Shandong Province, China. The present study aimed to assess the decennial change in SFT and body composition among children and adolescents in Shandong Province during the past 15 years (1995-2010).

METHODS

Data were obtained from two national surveys on student's constitution and health carried out by the government in 1995 and 2010 in Shandong Province, China. A total of 14 780 (7198 in 1995 and 7582 in 2010) students aged 7-18 years participated in the present study. Weight and SFT of all subjects were measured. Percentage body fat (%FM) was estimated by SFT, and fat mass (FM) and fat-free mass (FFM) were calculated from: FM (kg) = %FM × weight (kg)/100; FFM (kg) = weight (kg)-FM(kg). The range of differences of weight, SFT, FM and FFM over the different age groups between the 1995 and 2010 samples were calculated.

RESULTS

In the past 15 years, mean values of SFT have increased. The mean (range) increments of SFT were 6.28 (2.91-11.22) mm for boys and 3.29 (2.22-4.29) mm for girls, demonstrating a mean increase of 32% for boys and 14% for girls. The mean (range) increments of weight, FM and FFM were 7.26 (4.41-10.82) kg, 3.70 (1.47-6.58) kg and 3.56 (1.24-5.27) kg, at rates of 18%, 47% and 10% for boys, respectively, and 4.14 (2.78-5.64) kg, 1.68 (1.02-2.27) kg and 2.46 (1.52-3.49) kg, at rates of 11%, 20% and 8% for girls, respectively.

CONCLUSIONS

The mean values of SFT, FM and FFM have increased over time. Rates of increase were greater for FM than FFM.

Relative hypoadiponectinemia, insulin resistance, and increased visceral fat in euthyroid prepubertal girls with low-normal serum free thyroxine

A lower activity of the thyroid axis within the clinical reference range is related to a dysmetabolic phenotype in adult populations. We posited that such an association is already present as early as in prepubertal childhood. Serum thyroid stimulating hormone (TSH) and free T4, body fat (bioelectric impedance), insulin resistance (homeostasis model assessment of insulin resistance (HOMA(IR))), total and high molecular weight (HMW)-adiponectin and serum lipids were assessed in 234 euthyroid prepubertal children (113 boys and 121 girls) attending primary care clinics. Visceral fat (abdominal ultrasound) was measured in a subset of these subjects (n = 147; 74 boys and 73 girls). Explants of visceral adipose tissue from an additional six prepubertal children (three boys and three girls) were used to study the regulation of total and HMW-adiponectin by thyroid hormone. Serum free T4 was in girls independently associated with HMW-adiponectin, HOMA(IR) and visceral fat, so that circulating HMW-adiponectin decreased by 30% (β = 0.305 P < 0.005, R(2) = 0.13) and HOMA(IR) and visceral fat increased, respectively, by 90% (β = -0.255 P < 0.01, R(2) = 0.05) and 30% (β = -0.369, P < 0.005, R(2) = 0.12) from the highest to the lowest tertile of serum free T4. Nonsignificant differences in these parameters were found in boys. Treatment of visceral fat explants with thyroid hormone increased total and HMW-adiponectin by 70% and 53%, respectively, above control values (P < 0.01). In conclusion, a dysmetabolic phenotype, consisting of relative hypoadiponectinemia, insulin resistance and increased visceral fat, is associated with low-normal serum free thyroxine in euthyroid prepubertal girls. These associations may be partly explained by a positive regulation of HMW-adiponectin secretion by thyroid hormone.

Carotid intima-media thickness at 7 years of age: relationship to C-reactive protein rather than adiposity

OBJECTIVE

According to the concept of adipose tissue expandability, the vascular complications of obesity are related less to the amount of stored fat than to the low-grade inflammation that excess fat storage may elicit. We tested this concept in 7-year-old children by assessing whether carotid intima-media thickness (cIMT) is related to obesity measures or to circulating highly sensitive C-reactive protein (hsCRP), as a marker of low-grade inflammation.

STUDY DESIGN

The study group comprised 135 asymptomatic Caucasian children (72 girls and 63 boys; mean age, 7.1±1.1 years) with normal height and weight distributions. Relationships were assessed among cIMT, hsCRP, obesity measures (ie, body mass index [BMI], total fat by bioelectric impedance, and visceral fat by ultrasound), insulin resistance (by the homeostasis model assessment for insulin resistance), and fasting serum lipid levels.

RESULTS

cIMT was correlated with hsCRP, but not with BMI or body fat; the regression coefficients between cIMT and hsCRP (adjusted for age, sex, BMI, body fat, and serum lipid levels) were fairly similar across all BMI categories (β=0.370-0.411; all P<.001 to<.0001). Serum hsCRP increased with increasing BMI, total fat, and visceral fat (all P<.001).

CONCLUSION

At age 7 years, cIMT is already associated with low-grade inflammation, as measured by hsCRP, but not with BMI or body fat. These findings imply that public health strategies aimed at early prevention of cardiovascular disease may need to target low-grade inflammation rather than only BMI or adiposity.

Estimation of percentage body fat in 6- to 13-year-old children by skinfold thickness, body mass index and waist circumference

We evaluated the accuracy of skinfold thicknesses, BMI and waist circumference for the prediction of percentage body fat (PBF) in a representative sample of 372 Swiss children aged 6-13 years. PBF was measured using dual-energy X-ray absorptiometry. On the basis of a preliminary bootstrap selection of predictors, seven regression models were evaluated. All models included sex, age and pubertal stage plus one of the following predictors: (1) log-transformed triceps skinfold (logTSF); (2) logTSF and waist circumference; (3) log-transformed sum of triceps and subscapular skinfolds (logSF2); (4) log-transformed sum of triceps, biceps, subscapular and supra-iliac skinfolds (logSF4); (5) BMI; (6) waist circumference; (7) BMI and waist circumference. The adjusted determination coefficient (R² adj) and the root mean squared error (RMSE; kg) were calculated for each model. LogSF4 (R² adj 0.85; RMSE 2.35) and logSF2 (R² adj 0.82; RMSE 2.54) were similarly accurate at predicting PBF and superior to logTSF (R² adj 0.75; RMSE 3.02), logTSF combined with waist circumference (R² adj 0.78; RMSE 2.85), BMI (R² adj 0.62; RMSE 3.73), waist circumference (R² adj 0.58; RMSE 3.89), and BMI combined with waist circumference (R² adj 0.63; RMSE 3.66) (P < 0.001 for all values of R² adj). The finding that logSF4 was only modestly superior to logSF2 and that logTSF was better than BMI and waist circumference at predicting PBF has important implications for paediatric epidemiological studies aimed at disentangling the effect of body fat on health outcomes.

Pediatric body composition analysis with dual-energy X-ray absorptiometry

Pediatric applications of body composition analysis (BCA) have become of increased interest to pediatricians and other specialists. With the increasing prevalence of morbid obesity and with an increased awareness of anorexia nervosa, pediatric specialists are utilizing BCA data to help identify, treat, and prevent these conditions. Dual-energy X-ray absorptiometry (DXA) can be used to determine the fat mass (FM) and lean tissue mass (LTM), as well as bone mineral content (BMC). Among the readily available BCA techniques, DXA is the most widely used and it has the additional benefit of precisely quantifying regional FM and LTM. This review evaluates the strengths and limitations of DXA as a pediatric BCA method and considers the utilization of DXA to identify trends and variations in FM and LTM measurements in obese and anorexic children.

Pediatric body composition analysis with dual-energy X-ray absorptiometry

Pediatric applications of body composition analysis (BCA) have become of increased interest to pediatricians and other specialists. With the increasing prevalence of morbid obesity and with an increased awareness of anorexia nervosa, pediatric specialists are utilizing BCA data to help identify, treat, and prevent these conditions. Dual-energy X-ray absorptiometry (DXA) can be used to determine the fat mass (FM) and lean tissue mass (LTM), as well as bone mineral content (BMC). Among the readily available BCA techniques, DXA is the most widely used and it has the additional benefit of precisely quantifying regional FM and LTM. This review evaluates the strengths and limitations of DXA as a pediatric BCA method and considers the utilization of DXA to identify trends and variations in FM and LTM measurements in obese and anorexic children.

Establishment of the USDA/ARS Children's Nutrition Research Center at Baylor College of Medicine and Texas Children's Hospital in 1978

The Children's Nutrition Research Center (CNRC) is a unique cooperative venture among Baylor College of Medicine, Texas Children's Hospital, and the USDA/Agricultural Research Service. The CNRC is dedicated to defining the nutrient needs of children, from conception through adolescence, and the needs of pregnant women and nursing mothers. Scientific data from the Center enable healthcare providers and policy advisors to make dietary recommendations that improve the health of today's children and that of generations to come. CNRC research has already impacted feeding guidelines for normal U.S. children and all children of the world.

Body fat distribution in stunted compared with normal-height children from the shantytowns of São Paulo, Brazil

OBJECTIVE

The objective of this study was to determine whether central fat distribution varies between children who were growth retarded as young children and normal-height children from the same impoverished communities of São Paulo, Brazil.

METHODS

A prospective study of 50 stunted and normal-height children in São Paulo, Brazil was conducted in which children were measured for changes in fat mass (FM) and fat distribution (using dual-energy X-ray absorptiometry and anthropometry) and Tanner stage over a 4-y period. Statistical analyses included multiple linear regression to control for confounding factors and Student's t test was used to estimate group differences.

RESULTS

At follow-up, stunted children were shorter, weighed less, and had less total FM compared with control children. There were no differences between the two groups with respect to percent FM or percent truncal FM (%TrFM). Linear regression analyses were used to determine that stunted children had 1) increased TrFM (independent of FM); 2) increased %TrFM (independent of FM, gender, and Tanner stage), and 3) a borderline significantly greater change in TrFM (independent of FM, gender, and Tanner stage).

CONCLUSION

Stunted children are more likely to deposit fat centrally when entering puberty, a significant risk factor for chronic diseases. Our results may explain part of the association between early growth retardation and later risk for metabolic diseases.

Bone mineral content and body composition in overweight children and adolescents

The aim of this study was to analyze the bone mineral content (BMC) of the skeleton and the body composition in lean and fat masses in a population of young overweight subjects, before diet or medical intervention. A total of 496 white youths (298 females, 198 males) were studied. Their body mass index (BMI) values were 29.2+/-5.5 kg/m2 in females and 28.3+/-5.1 kg/m2 in males, corresponding to relative weights (wts) [actual wt, W, divided by the mean wt normal for height (ht), Wi] of 1.55+/-0.24 and 1.53+/-0.24, respectively. Whole-body dual-energy x-ray absorptiometry (DXA) scans were performed (Norland XR36 DXA system) to obtain the total BMC (BMCt), lean tissue mass (LTMt) and fat mass (FMt), as well as the values of the corresponding parameters in arms (a), legs (l), and abdomen (ab). The measured data were compared with theoretical values calculated for Wi. The differences with reference values in LTMt and FMt were sex dependent, and the accretion in FMt, greater in males than in females, yielded a similar FMt/LTMt ratio in both sexes. The wt corresponding to the BMC of the bearing skeleton, lower than the actual wt by about 20%, seemed a reasonable first step to consider in the wt management of these youths.

Comparison of predicted body fat percentage from anthropometric methods and from impedance in university students

The objective of the present study was to compare different methods for evaluating body fat percentage (BF%) (anthropometric methods and bioelectrical impedance analysis) in university students. Subjects were 653 healthy students whose mean age, body height, body weight and BMI were 21·1 (SD 2·5) years, 166·0 (SD 8·4) cm, 62·8 (SD 11·0) kg and 22·7 (SD 3·1) kg/m2, respectively. Results showed that BMI is a poor predictor of body fatness since the sensitivity was low in comparison with the reference method (Siri equation). The lowest values of BF% were obtained using the reference method (Siri equation) (21·8 (SD 6·8)%). The two methods with the highest agreement were Siri and Lean (mean difference, −0·5), followed by Brozek (mean difference, −1·4) and Deurenberg (mean difference, −1·5). The largest mean difference for BF% was between Siri and impedance (−4·5). Although the methods and/or equations used in the present study have been commonly utilised to estimate BF% in young adults, the results must be interpreted with caution in the diagnosis and monitoring of overweight and obesity.

Comparison of techniques to evaluate adiposity in stunted and nonstunted children

OBJECTIVE

The use of anthropometric measures (eg, skinfold thicknesses, BMI) to assess obesity is not without controversy and has not been explored with respect to the use among groups of children with growth retardation (ie, stunting). Therefore, the objective of this study was to determine whether growth retardation affects the accuracy of field methods for assessing body composition in children.

METHODS

A cross-sectional study was conducted in 30 stunted children and 30 nonstunted children who were matched for age- and weight-for-height z score and living in the shantytowns of São Paulo, Brazil. Body composition (fat mass, fat-free mass, and percentage of body fat [%BF]) was measured by H2(18)O dilution (reference technique) using group-specific values for the hydration of fat-free mass and dual-energy x-ray absorptiometry. BMI and body composition that were calculated from 3 pediatric skinfold prediction equations were evaluated for accuracy of %BF in comparison with the reference technique.

RESULTS

Stunted children were shorter and weighed less than nonstunted children, but BMI did not differ significantly between groups. All 3 skinfold equations tested resulted in a calculated %BF that was significantly lower than that measured by H2(18)O dilution for both stunted and nonstunted groups, and %BF as calculated by any of the skinfold equations tested did not significantly predict %BF by H2(18)O dilution. In contrast, BMI significantly predicted %BF in both stunted and nonstunted children, and this relationship did not differ by growth status.

CONCLUSION

BMI but not skinfolds significantly predicted %BF measured by H2(18)O dilution. The relationship between BMI and %BF did not differ between stunted and nonstunted children; this indicates that BMI can be used in field studies of obesity and stunting. However, the prediction of %BF by BMI is relatively poor in both groups of children, and continued investigation of more accurate field methods for measuring %BF is warranted.

Early programming of body composition and fat distribution in adolescents

Size at birth and early postnatal growth are determinants of adult height and BMI. The aim of this study was to evaluate the effect of birth weight on body composition and fat distribution in a group of Spanish adolescents. Current body composition was assessed by both skinfold thickness and dual X-ray absorptiometry in 234 adolescents born at term (140 girls and 94 boys), now aged 13-18 y and living in the city of Zaragoza. Relative fat distribution was estimated using the ratio of the subscapular to triceps skinfolds (S:T). Birth weight and gestational age were assessed by a questionnaire. Birth weight was inversely associated with the S:T ratio (P < 0.05) in boys and directly associated with bone mass (P < 0.01) and fat-free mass (P < 0.05) in girls. This association was independent of factors such as age, Tanner stage, gestational age, socioeconomic status, physical activity, and height. In conclusion, our data support the hypothesis that impaired fetal growth, measured by birth weight, may be related to central fat distribution in boys and decreased bone and fat-free mass in girls.

Bioimpedance electrical spectroscopy in the first six months of life: some methodologic considerations

OBJECTIVES

The objectives of this study were to evaluate the feasibility of using multifrequency bioelectrical impedance spectroscopy (BIS) in newborns and first-semester infants and to assess the influence of diverse methodologic and biological factors on BIS measurements.

METHODS

We studied 69 infants of both sexes, from the first day after birth through age 6 mo. They were healthy term infants who had no congenital malformations and were born in a low-income, peri-urban neighborhood of Guatemala City. The design was based on serial, repeated BIS measurements.

RESULTS

Overall mean values of extra- and intracellular resistance (mean+/-standard deviation) were 470.0+/-73.3 Omega and 604.6+/-179.2 Omega, respectively. We found statistical differences in both resistances in relation to advancing age and degree of movement while taking the measurements. With respect to repeat measurements by two separate observers, interobserver differences were a non-significant 7.6 Omega for both resistances. Restraining the infants and previous consumption of milk or formula had a significant effect on extracellular resistance measurements. The mean standard errors of measurement was 4.5 Omega for extracellular resistance and 73.9 Omega for intracellular resistance.

CONCLUSION

The BIS technique is feasible in newborn and young children when physiologic and methodologic aspects are respected or controlled.

Comparison of body fatness measurements by BMI and skinfolds vs dual energy X-ray absorptiometry and their relation to cardiovascular risk factors in adolescents

OBJECTIVE

To compare estimates of adiposity by dual emission X-ray absorptiometry (DXA), skinfolds and body mass index (BMI); and to evaluate the relation of these measures to cardiovascular risk in adolescents.

DESIGN

In a cohort of adolescents participating in a longitudinal study of insulin resistance, Slaughter formulas were used to estimate adiposity from skinfolds and DXA was used to estimate adiposity as % body fat (%BF) and fat mass (FBM). BMI, blood pressure, lipids and insulin resistance were measured.

SUBJECTS

Male and female, 11-17 y old (n=130).

MEASUREMENTS

To compare DXA with two office-based methods of assessing fatness and cardiovascular risk.

RESULTS

Slaughter estimates were highly correlated with DXA (%BF r=0.92, P=0.0001; FBM r=0.96, P=0.0001). Correlations were similar in heavy and thin children. BMI was also highly correlated with DXA (%BF r=0.85, P=0.0001; FBM r=0.95, P=0.0001), and these relations were stronger in heavy than thin children. BMI and the Slaughter formulas were similar to DXA in their relations to cardiovascular risk factors.

CONCLUSIONS

Adiposity by BMI and Slaughter formulas are highly correlated with DXA and similarly related to cardiovascular risk factors. BMI is easy to obtain and is an acceptable method for initial office estimation of body fatness. BMI and skinfolds compare well with DXA in predicting adverse cardiovascular risk profile.

Assessing body composition among 3- to 8-year-old children: anthropometry, BIA, and DXA

OBJECTIVE

To examine the inter-relationships of body composition variables derived from simple anthropometry [BMI and skinfolds (SFs)], bioelectrical impedance analysis (BIA), and dual energy x-ray (DXA) in young children.

RESEARCH METHODS AND PROCEDURES

Seventy-five children (41 girls, 34 boys) 3 to 8 years of age were assessed for body composition by the following methods: BMI, SF thickness, BIA, and DXA. DXA served as the criterion measure. Predicted percentage body fat (%BF), fat-free mass (FFM; kilograms), and fat mass (FM; kilograms) were derived from SF equations [Slaughter (SL)1 and SL2, Deurenberg (D) and Dezenberg] and BIA. Indices of truncal fatness were also determined from anthropometry.

RESULTS

Repeated measures ANOVA showed significant differences among the methods for %BF, FFM, and FM. All methods, except the D equation (p = 0.08), significantly underestimated measured %BF (p < 0.05). In general, correlations between the BMI and estimated %BF were moderate (r = 0.61 to 0.75). Estimated %BF from the SL2 also showed a high correlation with DXA %BF (r = 0.82). In contrast, estimated %BF derived from SFs showed a low correlation with estimated %BF derived from BIA (r = 0.38); likewise, the correlation between DXA %BF and BIA %BF was low (r = 0.30). Correlations among indicators of truncal fatness ranged from 0.43 to 0.98.

DISCUSSION

The results suggest that BIA has limited utility in estimating body composition, whereas BMI and SFs seem to be more useful in estimating body composition during the adiposity rebound. However, all methods significantly underestimated body fatness as determined by DXA, and, overall, the various methods and prediction equations are not interchangeable.

Prematurity and reduced body fatness at 8-12 y of age

BACKGROUND

Increasing evidence suggests that body composition, an important factor influencing morbidity and mortality in adult life, might be programmed by early growth and nutrition. Children born preterm remain shorter and lighter than their term-born peers during childhood, but it is unclear whether the size difference is associated with altered body composition.

OBJECTIVE

We tested the hypothesis that both fat mass (FM) and fat-free mass (FFM) are proportionately lower in children born preterm than in children born at term.

DESIGN

A total of 497 children born preterm and 95 children born at term were studied at 8-12 y of age. Body composition was determined with the use of skinfold thicknesses and dual-energy X-ray absorptiometry (in 200 preterm and 95 term children). FM and FFM were normalized for height to give fat mass index (FMI) and fat-free mass index (FFMI), respectively.

RESULTS

Children born preterm were significantly lighter than those born at term and had lower FM and FFM. However, FMI was significantly lower in preterm children, whereas FFMI was not. FMI was also significantly lower in boys than in girls and in children with higher activity levels. Additional data available for the preterm group showed no association between birth weight, gestational age, or neonatal diet and later FMI or FFMI.

CONCLUSIONS

The smaller size of children born preterm than of children born at term is associated with lower FM but not FFM when normalized for height. We hypothesize that this could result in a reduction in the risk of obesity and related diseases during adult life.

Annual Changes in Bone Mineral Content and Body Composition during Growth

OBJECTIVES

To compute the annual changes in total bone mineral content (BMCt), lean tissue mass and fat mass (LTM and FM) during growth.

METHODS

Whole body DXA data were used to calculate the annual changes of the parameter P (P = BMCt, LTM or FM), as a percentage, as DeltaP% = 100 x (P(i+1) - P(i)) / P(i); with P(i) and P(i+1) the values for P at age i and age (i+1). Smoothed curves were then obtained from DeltaP% values plotted against age.

RESULTS

Changes in FM were different in males and females. A peak velocity was marked for the three tissues at age 6.5 in boys, and at age 6.5-7.5 in girls; a pubertal peak spurt appeared at age 12 in girls and between age 13 and 14 in boys. This latter peak was followed by an exponential decrease, and no significant changes were found for the three components after age 20 in girls and age 21-22 in boys.

CONCLUSION

Changes in tissue accretion during growth are easy to follow when expressed in percentages. Fat changes, especially, should be around 17% in girls and 15% in boys at the age of puberty.