Predicting body composition from anthropometry in pre-adolescent children

Prediction of body-fat percentage from skinfold and bio-impedance measurements in Indian school children

BACKGROUND/OBJECTIVES

Few equations for calculating body-fat percentage (BF%) from field methods have been developed in South-Asian children. The objective of this study was to assess agreement between BF% derived from primary reference methods and that from skinfold equations and bio-impedance analysis (BIA) in Indian children.

SUBJECTS/METHODS

We measured BF% in two groups of Indian children. In Pune, 570 rural children aged 6-8 years underwent dual-energy X-ray absorptiometry (DXA) scans. In Mysore (18)O in doubly labeled water was administered to 59 urban children aged 7-9 years. We conducted BIA at 50 kHz and anthropometry, including sub-scapular and triceps skinfold thicknesses. We used the published equations of Wickramasinghe, Shaikh, Slaughter and Dezenburg to calculate BF% from anthropometric data and the manufacturer's equation for BIA measurements. We assessed agreement with values derived from DXA and doubly labeled water using Bland-Altman analysis.

RESULTS

Children were light and thin on average compared with international standards. There was poor agreement between the reference BF% values and those from all equations. Assumptions for Bland-Altman analysis were not met for Wickramasinghe, Shaikh and Slaughter equations. The Dezenberg equations under-predicted BF% for most children (mean difference in Pune -13.4, LOA -22.7, -4.0 and in Mysore -7.9, LOA (-13.7 and -2.2). The mean bias for the BIA equation in Pune was +5.0% and in Mysore +1.95%, and the limits of agreement were wide; -5.0, 15.0 and -7.8, 11.7 respectively.

CONCLUSIONS

Currently available skinfold equations do not accurately predict BF% in Indian children. We recommend development of BIA equations in this population using a four-compartment model.

Integrating a family-focused approach into child obesity prevention: rationale and design for the My Parenting SOS study randomized control trial

BACKGROUND

More than 20% of US children ages 2-5 yrs are classified as overweight or obese. Parents greatly influence the behaviors their children adopt, including those which impact weight (e.g., diet and physical activity). Unfortunately, parents often fail to recognize the risk for excess weight gain in young children, and may not be motivated to modify behavior. Research is needed to explore intervention strategies that engage families with young children and motivate parents to adopt behaviors that will foster healthy weight development.

METHODS

This study tests the efficacy of the 35-week My Parenting SOS intervention. The intervention consists of 12 sessions: initial sessions focus on general parenting skills (stress management, effective parenting styles, child behavior management, coparenting, and time management) and later sessions apply these skills to promote healthier eating and physical activity habits. The primary outcome is change in child percent body fat. Secondary measures assess parent and child dietary intake (three 24-hr recalls) and physical activity (accelerometry), general parenting style and practices, nutrition- and activity-related parenting practices, and parent motivation to adopt healthier practices.

DISCUSSION

Testing of these new approaches contributes to our understanding of how general and weight-specific parenting practices influence child weight, and whether or not they can be changed to promote healthy weight trajectories.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00998348.

Desempenho de diferentes equações antropométricas na predição de gordura corporal excessiva em crianças e adolescentes

OBJETIVO: O objetivo do presente estudo foi analisar a eficiência de diferentes equações antropométricas para a identificação de excesso de gordura corporal entre crianças e adolescentes. MÉTODOS: A amostra foi composta por 1.498 indivíduos (678 meninos e 820 meninas), com idade entre 7 e 17 anos (M=13,7, DP=2,0), da cidade de Presidente Prudente (SP). A massa corporal e a estatura foram mensuradas para o cálculo do Índice de Massa Corporal. Também foi realizada a mensuração da circunferência de cintura e das dobras cutâneas subescapular, tricipital, abdominal e da panturrilha. O percentual de gordura corporal foi calculado por meio de quatro equações: Slaughter et al., Slaughter II et al., Dezenberg et al., e Deurenberg et al.. Para indicar a eficiência das diferentes equações antropométricas na indicação da obesidade, foi utilizada a análise da curva Receiver Operating Characteristic Curve. RESULTADOS: No grupo masculino, foram observados valores de sensibilidade elevados (82,4% a 100,0%) e valores oscilando de baixo a alto, para a especificidade (20,9% a 94,9%). Para o sexo feminino, os valores de sensibilidade variaram entre moderado e alto (72,2% a 99,4%); e os de especificidade apresentaram, também, grande oscilação entre baixo e alto (21,6% a 98,2%). CONCLSÃO: A equação proposta por Deurenberg et al., apresentou o melhor desempenho no diagnóstico tanto da presença como da ausência de obesidade na amostra investigada.

Aerobic fitness in prepubertal children according to level of body fat

AIM

The purpose of this study was to investigate the relationship between maximum oxygen uptake (VO(2PEAK) ) and body fat in young children on a population-based level.

METHODS

Participants were 586 children (311 boys and 275 girls) aged 6.8±0.4 years, recruited from a population-based cohort. VO(2PEAK) was measured by indirect calorimetry during a maximal exercise test. Percent body fat (BF%) was estimated from skinfold measurements.

RESULTS

  Significant relationships existed between BF% and absolute values of VO(2PEAK) (mL/min), VO(2PEAK) scaled by body weight (mL/min/kg) and VO(2PEAK) by allometric scaling (mL/min/kg(0.71) ), whereas no relationships were detected for VO(2PEAK) scaled to fat-free mass (FFM) (mL/min/FFM). Person correlation coefficients for boys were 0.26, -0.38, -0.19 and -0.01 NS and for girls 0.33, -0.42, -0.21 and -0.03 NS, respectively. Significant differences in VO(2PEAK) existed between different quartiles of BF%, with the exception when VO(2PEAK) was scaled to FFM.

CONCLUSION

 Our findings document the coexistence of two known risk factors for disease at a young age on a population-base and confirms that VO(2PEAK) was scaled to FFM represents a body fat independent way of expressing fitness.

Atypical progeroid syndrome due to heterozygous missense LMNA mutations

CONTEXT

Hutchinson-Gilford progeria syndrome (HGPS) and mandibuloacral dysplasia are well-recognized allelic autosomal dominant and recessive progeroid disorders, respectively, due to mutations in lamin A/C (LMNA) gene. Heterozygous LMNA mutations have also been reported in a small number of patients with a less well-characterized atypical progeroid syndrome (APS).

OBJECTIVE

The objective of the study was to investigate the underlying genetic and molecular basis of the phenotype of patients presenting with APS.

RESULTS

We report 11 patients with APS from nine families, many with novel heterozygous missense LMNA mutations, such as, P4R, E111K, D136H, E159K, and C588R. These and previously reported patients now reveal a spectrum of clinical features including progeroid manifestations such as short stature, beaked nose, premature graying, partial alopecia, high-pitched voice, skin atrophy over the hands and feet, partial and generalized lipodystrophy with metabolic complications, and skeletal anomalies such as mandibular hypoplasia and mild acroosteolysis. Skin fibroblasts from these patients when assessed for lamin A/C expression using epifluorescence microscopy revealed variable nuclear morphological abnormalities similar to those observed in patients with HGPS. However, these nuclear abnormalities in APS patients could not be rescued with 48 h treatment with farnesyl transferase inhibitors, geranylgeranyl transferase inhibitors or trichostatin-A, a histone deacetylase inhibitor. Immunoblots of cell lysates from fibroblasts did not reveal prelamin A accumulation in any of these patients.

CONCLUSIONS

APS patients have a few overlapping but some distinct clinical features as compared with HGPS and mandibuloacral dysplasia. The pathogenesis of clinical manifestations in APS patients seems not to be related to accumulation of mutant farnesylated prelamin A.

Influence of a lifestyle intervention in preschool children on physiological and psychological parameters (Ballabeina): study design of a cluster randomized controlled trial

BACKGROUND

Childhood obesity and physical inactivity are increasing dramatically worldwide. Children of low socioeconomic status and/or children of migrant background are especially at risk. In general, the overall effectiveness of school-based programs on health-related outcomes has been disappointing. A special gap exists for younger children and in high risk groups.

METHODS/DESIGN

This paper describes the rationale, design, curriculum, and evaluation of a multicenter preschool randomized intervention study conducted in areas with a high migrant population in two out of 26 Swiss cantons. Twenty preschool classes in the German (canton St. Gallen) and another 20 in the French (canton Vaud) part of Switzerland were separately selected and randomized to an intervention and a control arm by the use of opaque envelopes. The multidisciplinary lifestyle intervention aimed to increase physical activity and sleep duration, to reinforce healthy nutrition and eating behaviour, and to reduce media use. According to the ecological model, it included children, their parents and the teachers. The regular teachers performed the majority of the intervention and were supported by a local health promoter. The intervention included physical activity lessons, adaptation of the built infrastructure; promotion of regional extracurricular physical activity; playful lessons about nutrition, media use and sleep, funny homework cards and information materials for teachers and parents. It lasted one school year. Baseline and post-intervention evaluations were performed in both arms. Primary outcome measures included BMI and aerobic fitness (20 m shuttle run test). Secondary outcomes included total (skinfolds, bioelectrical impedance) and central (waist circumference) body fat, motor abilities (obstacle course, static and dynamic balance), physical activity and sleep duration (accelerometry and questionnaires), nutritional behaviour and food intake, media use, quality of life and signs of hyperactivity (questionnaires), attention and spatial working memory ability (two validated tests). Researchers were blinded to group allocation.

DISCUSSION

The purpose of this paper is to outline the design of a school-based multicenter cluster randomized, controlled trial aiming to reduce body mass index and to increase aerobic fitness in preschool children in culturally different parts of Switzerland with a high migrant population.

TRIAL REGISTRATION

Trial Registration: (clinicaltrials.gov) NCT00674544.

Severe mandibuloacral dysplasia-associated lipodystrophy and progeria in a young girl with a novel homozygous Arg527Cys LMNA mutation

CONTEXT

Mandibuloacral dysplasia (MAD) is a rare autosomal recessive progeroid syndrome due to mutations in genes encoding nuclear lamina proteins, lamins A/C (LMNA) or prelamin A processing enzyme, and zinc metalloproteinase (ZMPSTE24).

OBJECTIVE

The aim of the study was to investigate the underlying genetic and molecular basis of the phenotype of a 7-yr-old girl with MAD belonging to a consanguineous pedigree and with severe progeroid features and lipodystrophy.

DESIGN AND PATIENT

The patient developed mandibular hypoplasia during infancy and joint stiffness, skin thinning, and mottled hyperpigmentation at 15 months. Progressive clavicular hypoplasia, acroosteolysis, and severe loss of hair from the temporal and occipital areas were noticed at 3 yr. At 5 yr, cranial sutures were still open and lipodystrophy of the limbs was prominent. GH therapy from the ages of 3-7 yr did not improve the short stature. Severe joint contractures resulted in abnormal posture and decreased mobility. We studied her skin fibroblasts for nuclear morphology and immunoblotting and determined the in vitro effects of various pharmacological interventions on fibroblasts.

RESULTS

LMNA gene sequencing revealed a homozygous missense mutation, c.1579C>T, p.Arg527Cys. Immunoblotting of skin fibroblast lysate with lamin A/C antibody revealed no prelamin A accumulation. Immunofluorescence staining of the nuclei for lamin A/C in fibroblasts revealed marked nuclear morphological abnormalities. This abnormal phenotype could not be rescued with inhibitors of farnesyl transferase, geranylgeranyl transferase, or histone deacetylase.

CONCLUSION

Severe progeroid features in MAD could result from LMNA mutation, which does not lead to accumulation of prenylated lamin A or prelamin A.

Use of bioelectrical impedance analysis to assess body composition in rural Gambian children

OBJECTIVE

To validate the Tanita BC-418MA Segmental Body Composition Analyser and four-site skinfold measurements for the prediction of total body water (TBW), percentage fat-free mass (%FFM) and percentage body fat (%BF) in a population of rural Gambian children.

SUBJECTS/METHODS

One hundred and thirty-three healthy Gambian children (65 males and 68 females). FFM estimated by the inbuilt equations supplied with the Tanita system was assessed by comparison with deuterium oxide dilution and novel prediction equations were produced. Deuterium oxide dilution was also used to develop equations for %BF based on four-site skinfolds (biceps, triceps, subscapular and suprailiac).

RESULTS

The inbuilt equations underestimated FFM compared to deuterium oxide dilution in all the sex and age categories (P<0.003), with greater accuracy in younger children and in males. The best prediction of %FFM was obtained from the variables height, weight, sex, impedance, age and four skinfold thickness measurements (adjusted R(2)=0.84, root mean square error (MSE)=2.07%).

CONCLUSIONS

These data suggest that the Tanita instrument may be a reliable field assessment technique in African children, when using population and gender-specific equations to convert impedance measurements into estimates of FFM.

[Waist circumference, dyslipidemia and hypertension in prepubertal children]

OBJECTIVE

To explore the relationship between anthropometric variables, lipid concentrations and blood pressure in a sample of prepubertal children and to asses the importance of waist circumference in identifying certain cardiovascular risk factors in this age group.

METHODS

A cross-sectional analysis of a random sample of prepubertal children aged 2 to 9 years old was performed. Height, weight, triceps skinfold, body mass index, waist circumference, and systolic and diastolic blood pressure were measured. Plasma levels of triglycerides, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and glucose were determined.

RESULTS

A total of 240 prepubertal children were studied. There were 123 (51.3 %) boys and 117 (48.8 %) girls. The prevalence of overweight, high blood pressure and insulin-resistance syndrome was 16.6 %, 3.7 % and 1.2 %, respectively. Triceps skinfold and fat mass were significantly higher in girls. There were no significant differences in lipid profiles between obese children and those with a healthy weight. Waist circumference had a positive and significant correlation with high-density lipoprotein cholesterol, systolic blood pressure, and diastolic blood pressure. Furthermore, waist circumference was also associated with a greater risk of elevated values of total cholesterol, triglycerides and hypertension.

CONCLUSION

Waist circumference may be a helpful parameter in identifying prepubertal children with an adverse lipid profile and hypertension.

Measurement and definitions of obesity in childhood and adolescence: a field guide for the uninitiated

This paper aims to guide readers embarking on the complex literature in respect of childhood and adolescent obesity. It opens with a discussion of definitions of 'obesity' based on overall fat levels and the significance of fat distribution. This is followed by simple descriptions of the various techniques used to measure fat, including density-based, scanning, bioelectrical impedance and anthropometric methods. The paper then turns to 'overweight' and the measurement of weight in relation to height, particularly via body mass index (BMI). While it is a relatively simple measure and a valuable tool, BMI has several disadvantages, which are described. These include a lack of consensus on which values should be used to define 'overweight' or 'obese', with the result that the literature contains a confusing multiplicity of child and adolescent obesity rates.

Effect of physical activity intervention on body composition in young children: influence of body mass index status and gender

Aim

To fight overweight and obesity in childhood, this study proposes an additional physical activity (PA) in young children aged 6–10 years. The objective was to evaluate the effect of school-based PA on the body composition according to body mass index (BMI) categories (nonobese vs. obese) and gender.

Methods

This 6-month study examined the effect of this intervention on body composition in 425 children in 14 primary schools (2 weekly PA sessions of 1 h each) compared to 5 control schools. Adiposity indices were evaluated or calculated: BMI, BMI z-score, waist circumference, sum of skinfolds and fat-free mass.

Results

No difference in the prevalence of obesity and anthropometric characteristics was found between the intervention and control groups at baseline. In girls, PA intervention had significant effect on all anthropometric variables (p < 0.05 to p < 0.001), except on BMI. In contrast, in boys only BMI z-score (p < 0.001) and fat-free mass (p < 0.001) were affected.

Conclusions

Six months of preventive PA intervention offer an effective means to improve body composition in obese children. The pattern of response related to PA was similar between girls and boys. In contrast, the pattern was different according to BMI category, with a higher response in obese than nonobese children.

Evaluation of two foot-to-foot bioelectrical impedance analysers to assess body composition in overweight and obese adolescents

The objective of the present study was to determine the accuracy of two foot-to-foot (FF) bioelectrical impedance analysers (BIA) to assess body composition in overweight and obese adolescents, compared with dual-energy X-ray absorptiometry (DXA) and hand-to-foot (HF) BIA. Body composition was assessed in fifty-three overweight or obese adolescents (BMI 27·9 (sd 4·1) kg/m2; aged 13–16 years) by DXA (Hologic QDR-4500; Hologic Inc., Bedford, MA, USA) and BIA (HF (BIA 101, RJL System, Detroit, IL, USA) and FF (Body Fat Monitor Scale BF-625, Tanita Corporation of America Inc., Arlington Heights, IL, USA; Téfal Bodymaster Vision, Téfal, Rumilly, France)). Bland–Altman tests showed that, compared with DXA, FF-Tanita and FF-Téfal underestimated (P<0·05) fat mass (FM) less than HF-BIA (−1·7 (sd 3·1), −0·7 (sd 5·8) and −2·3 (sd 2·2) kg respectively, P<0·001). However, the limits of agreement between DXA and FF-Tanita or FF-Téfal were much greater than those obtained with HF-BIA (−7·7 and +4·3, −12·0 and +10·6 v. −2·1 and +6·7kg respectively). The differences between FM assessed using the FF-Tanita or the FF-Téfal analyser and DXA increased with the waist:hip ratio, and were higher in boys than in girls. The major limiting factor of FF-BIA was the inter-individual variability in FM estimates. In conclusion, FF-BIA and DXA are not interchangeable methods. FF-BIA could be acceptable to assess body composition in large groups of overweight or obese adolescents, but cannot be recommended for body composition assessment in obese subjects because of the large errors in individual estimates.

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.

Do Skinfolds Accurately Assess Changes in Body Fat in Obese Children and Adolescents?

PURPOSE

Obesity is epidemic in Western societies, with rapid rates of increase in the young. Various methods exist for the assessment of body composition, but these have not been compared in obese children and adolescents. This study compared methods of body composition assessment in obese young people to determine whether changes in various measures of body composition as a result of exercise training were correlated.

METHODS

Multiple anthropometric measures (weight, height, body mass index (BMI), skinfolds, waist and hip girths) and dual-energy x-ray absorptiometry (DEXA) were undertaken in 38 obese children and adolescents (12.7 +/- 2.1 yr) at baseline and following 8 wk of exercise training.

RESULTS

At baseline, there were strong relationships (all P < 0.01) between DEXA total fat and weight (r = 0.83), BMI (r = 0.86), waist girth (r = 0.81), hip girth (r = 0.88), sum of six skinfolds (sum6, r = 0.79), and percent body fat (percent body fat) calculated using a four-skinfold equation (EQ4; r = 0.69). Similar relationships (all P < 0.001) existed between DEXA abdominal fat and weight (r = 0.79), waist girth (r = 0.83), hip girth (r = 0.69), and height (r = 0.71). Neither skinfold sums, nor percent body fat calculated from skinfold equations, were selected as independent predictors of DEXA total or abdominal fat by stepwise hierarchical linear regression. The reductions in DEXA total and abdominal fat following exercise were not predicted by changes in skinfolds or percent body fat calculated from skinfolds.

CONCLUSION

These data suggest that body fat derived from skinfold measures is poorly predictive of abdominal and total fat derived from DEXA in obese children and adolescents. This finding highlights the limitations of skinfolds in obese subjects and questions the validity of their use to assess changes in body composition with interventions such as exercise training.

Maximum oxygen uptake and objectively measured physical activity in Danish children 6-7 years of age: the Copenhagen school child intervention study

OBJECTIVES

To provide normative data on maximum oxygen uptake (Vo(2)max) and physical activity in children 6-7 years of age and analyse the association between these variables.

METHODS

Vo(2)max was measured in 366 boys (mean (SD) 6.8 (0.4) years of age) and 332 girls (6.7 (0.4) years of age) from preschool classes in two suburban communities in Copenhagen, during a progressive treadmill exercise. Habitual physical activity was measured with accelerometers.

RESULTS

Boys had higher Vo(2)max both in absolute values (1.19 (0.18) v 1.06 (0.16) litres/min (+11%), p<0.001) and relative to body weight (48.5 (6.0) v 44.8 (5.6) ml/kg/min (+8%); p<0.001) than girls. The difference in Vo(2)max between boys and girls decreased to +2% when expressed relative to lean body mass (LBM). Absolute Vo(2)max was related to LBM, body mass, and stature (all p<0.001). Boys were more physically active than girls (mean counts +9.4%, p<0.001), and even when boys and girls with the same Vo(2)max were compared, boys were more active. The difference in physical activity between the sexes was higher when sustained activity of higher intensity was compared.

CONCLUSIONS

Vo(2)max is higher in boys than girls (+11%), even when related to body mass (+8%) and LBM (+2%). Most of the difference in Vo(2)max relative to body mass was explained by the larger percentage body fat in girls. When boys and girls with the same Vo(2)max were compared, boys engaged in more minutes of exercise of at least moderate intensity.

Overweight and stunting in migrant Hispanic children in the USA

In order to evaluate the need for preventive interventions to improve nutrition, the BMI/sex/age percentile, height/sex/age percentile, prevalence of stunting, at-risk-for-overweight and overweight in a group of migrant Hispanic children, aged 2-18, in southern New Jersey, USA, was assessed using anthropometric measurements of height, weight and skinfold thickness with reference to the NHANES 1999-2000. Results showed that the frequency of overweight in this sample--20%--exceeds that of the general U.S. pediatric population and equals or exceeds (in 2-5-year olds) that of settled Mexican-Americans. Being born in the U.S. significantly diminished the prevalence of stunting, especially in boys. The children of migrant Hispanic agricultural workers belong to a marginalized, poor and insecure population who are not included in the National Health and Nutrition Examination studies, because of their transience. This is the first anthropometric study to evaluate growth in this population in over 20 years.

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.

Comparison of methods to assess change in children's body composition

BACKGROUND

Little is known about how simpler and more available methods to measure change in body fatness compare with criterion methods such as dual-energy X-ray absorptiometry (DXA) in children.

OBJECTIVE

Our objective was to determine the ability of air-displacement plethysmography (ADP) and formulas based on triceps skinfold thickness (TSF) and bioelectrical impedance analysis (BIA) to estimate changes in body fat over time in children.

DESIGN

Eighty-six nonoverweight and overweight boys (n = 34) and girls (n = 52) with an average age of 11.0 +/- 2.4 y underwent ADP, TSF measurement, BIA, and DXA to estimate body fatness at baseline and 1 +/- 0.3 y later. Recent equations were used to estimate percentage body fat by TSF measurement (Dezenberg equation) and by BIA (Suprasongsin and Lewy equations). Percentage body fat estimates by ADP, TSF measurement, and BIA were compared with those by DXA.

RESULTS

All methods were highly correlated with DXA (P < 0.001). No mean bias for estimates of percentage body fat change was found for ADP (Siri equation) compared with DXA for all subjects examined together, and agreement between body fat estimation by ADP and DXA did not vary with race or sex. Magnitude bias was present for ADP relative to DXA (P < 0.01). Estimates of change in percentage body fat were systematically overestimated by BIA equations (1.37 +/- 6.98%; P < 0.001). TSF accounted for only 13% of the variance in percentage body fat change.

CONCLUSION

Compared with DXA, there appears to be no noninvasive and simple method to measure changes in children's percentage body fat accurately and precisely, but ADP performed better than did TSF or BIA. ADP could prove useful for measuring changes in adiposity in children.

Regression equations to estimate percentage body fat in African prepubertal children aged 9 y

BACKGROUND

The regression equations of Slaughter and Dezenberg, which are based on mixed ethnic samples, are currently recommended for predicting body fat from skinfold-thickness measures in prepubescent children of African ancestry. These equations contain methodologic problems that could make them inappropriate for African children.

OBJECTIVE

The objective was to apply the Slaughter and Dezenberg equations to predict body fat in African prepubertal children and to compare the results with body fat measured by dual-energy X-ray absorptiometry (DXA). If significantly different outcomes were observed, then the objective was to develop new prediction equations and validate them on African children.

DESIGN

The Slaughter and Dezenberg equations were applied to a cross-sectional sample of 214 prepubescent (Tanner stage 1) African children (118 boys). Body fat was determined by DXA, and subcutaneous fat at triceps, biceps, subscapular, suprailiac, thigh, and calf sites was measured with use of Holtain calipers. A randomly selected sample of 134 participants (78 boys) was used to generate new prediction equations that were validated on the remaining 80 participants (40 boys).

RESULTS

The Slaughter and Dezenberg equations significantly underestimated (P < 0.001) body fat compared with DXA in both boys and girls. The best combination of skinfold thicknesses to predict body fat in African prepubertal boys, controlling for chronologic age, was triceps, biceps, subscapular, suprailiac, and thigh (SEE = 2.87), and for girls it was biceps, subscapular, suprailiac, thigh, and calf (SEE = 3.51).

CONCLUSION

The Slaughter and Dezenberg equations are unsuitable for predicting body fat in 9-y-old African prepubertal children. New equations that are based on skinfold-thickness combinations from African children provide more accurate estimates.

School-based obesity prevention in Chilean primary school children: methodology and evaluation of a controlled study

OBJECTIVE

To assess the impact of a 6 months nutrition education and physical activity intervention on primary school children through changes in adiposity and physical fitness.

DESIGN

Longitudinal school-based controlled evaluation study.

SUBJECTS

Children from 1st to 8th grade, 2141 in intervention and 945 in control schools.

INTERVENTION

Nutrition education for children and parents, 'healthier' kiosks, 90 min of additional physical activity (PA) weekly, behavioral PA program and active recess.

MEASUREMENTS

Adiposity indices (BMI, BMI Z-score, triceps skinfold thickness (TSF), waist circumference and physical fitness (20 m shuttle run test and lower back flexibility).

RESULTS

Positive effect on adiposity indices (except TSF) was observed in boys (P<0.001 for BMI Z), while both physical fitness parameters increased significantly in both boys (P<0.001 for each test) and girls (P<0.0001 for each test). A differential effect in BMI Z was observed according to baseline nutritional status.

CONCLUSIONS

This intervention showed a robust effect on physical fitness in both genders and decreased adiposity only in boys.

Anthropometric assessment of muscularity during growth: estimating fat-free mass with 2 skinfold-thickness measurements is superior to measuring midupper arm muscle area in healthy prepubertal children

BACKGROUND

Anthropometric measurements are widely used to determine body composition, especially in children.

OBJECTIVE

Our aim was to compare 2 of the simplest anthropometry-based equations available for determining nutritional status and muscularity in children and adolescents, examined in relation to other methodologically independent muscle variables.

DESIGN

Midupper arm muscle area (UAMA) and fat-free mass (FFM) according to the equations of Slaughter et al (Hum Biol 1988;60:709-23), as well as separate biochemical, physical, and radiologic muscle variables, were determined cross-sectionally in 91 males and 91 females aged 6-18 y. The ability of UAMA and FFM to estimate muscularity, as measured by 24-h creatinine excretion, grip force, and peripheral quantitative computer tomography analysis of forearm muscle, was compared after dividing the study population into prepubertal and pubertal groups.

RESULTS

Before puberty, correlations of all 3 muscularity variables were higher with FFM than with UAMA in both males and females. Multiple regression analyses confirmed FFM to be the predominant predictor, with partial R(2) >/= 0.68 (P < 0.001). However, in puberty, FFM did not consistently show this major influence. Only before puberty did FFM provide a significantly better fit (P < 0.05) than did UAMA for 2 of the 3 muscularity variables in each sex.

CONCLUSIONS

The FFM estimate proved to be the better predictor for muscularity in healthy prepubertal children and is on a par with UAMA during puberty. FFM can be recommended as a simple anthropometric method to assess nutritional status before puberty, at least in healthy children.

Underestimation of percentage fat mass measured by bioelectrical impedance analysis compared to dual energy X-ray absorptiometry method in obese children

OBJECTIVE

The aim of the study was to investigate whether there is a difference between body fat mass percentage measured by BIA and DXA method.

DESIGN

Transversal study, randomized.

SETTING

Lipid and Obesity Outpatient Clinic, Department of Pediatrics, University of Vienna, Austria.

SUBJECTS

Twenty-seven children and adolescents from the Lipid and Obesity Outpatient Clinic, Department of Pediatrics, University of Vienna, were included in the study (14 boys and 13 girls between 6 and 18 y; mean age 12.6 and 13.1 y).

METHODS

The body fat percentage was measured with BIA (bioelectrical impedance analyzer BIA 2000-M) and DXA (dual energy X-ray absorptiometry) methods on the same day.

RESULTS

The mean difference between the body fat mass percentage measured by BIA and DXA was 4.48 with a standard deviation of 2.93. The results measured by BIA were almost always lower than that by DXA by about 12%. The lower and upper limit of the difference in 95% confidence interval was -5.64 and -3.32. By paired t-test, these results were significantly different (P<0.001). The correlation between the two measurements was 0.826. The mean percentage of body fat mass measured by BIA was 34.86+/-7.08% and by DXA 39.75+/-5.63%. The differences were not changed by age and body fat percentage but they were by sex.

CONCLUSIONS

The results of the study show that the body fat percentages measured by BIA and DXA method were significantly different. This is very important because BIA technique is a routine technique for clinical purposes. Adjustments to the formula used for calculating the total fat mass in obese children and adolescence are necessary. Underestimation of body fat percentage measured by bioelectrical impedance analysis compared to dual X-ray absorptiometry method in obese children is three times higher with boys than with girls.

Parameters of childhood obesity and their relationship to cardiovascular risk factors in healthy prepubescent children

OBJECTIVE

To investigate which of the currently applied parameters to assess childhood overweight best predict cardiovascular risk factors.

DESIGN

Cross-sectional study comparing five different methods to define overweight with respect to their power to predict cardiovascular risk factors.

SUBJECTS

A total of 838 healthy children from the Prevention-Education-Program (Nuremberg, Germany; age 4-9 y, 405 boys, 433 girls).

MEASUREMENTS

Obesity parameters-body mass index (BMI), ponderal index (PI), the sum of triceps and subscapular skinfold thickness (SFT), percentage body fat (%BF) using SFT and two different regression formulas (Slaughter, %BF-SL; Dezenberg, %BF-DZ). Overweight defined by the 90th age- and sex-specific percentile of each obesity parameter. Comparison of LDL- and HDL-cholesterol, apolipoprotein-B (apo-B), triglycerides (TG), fibrinogen and blood pressure values (SBP/DBP) between normal-weight and overweight children.

RESULTS

When overweight is defined by BMI or PI, all cardiovascular risk factors are significantly (P<0.01) different between overweight and normal-weight children (BMI: TG+20.5%, HDL-chol.-8.6%, LDL-chol.+9.6%, apo-B+6.8%, SBP+7.4%, DBP+8.6%, fibrinogen+13.2%; PI: TG+24.3%, HDL-chol.-6.1%, LDL-chol.+9.0%, apo-B+7.4%, SBP+5.9%, DBP+6.7%, fibrinogen+13.9%), while SFT, %BF-SL and %BF-DZ did not predict all cardiovascular risk factors. A sex-specific analysis showed that in girls BMI and PI both predict cardiovascular risk factors, while in boys this is only valid for BMI.

CONCLUSION

In prepubescent children, height-to-weight indices such as BMI or PI better predict cardiovascular risk factors than obesity parameters using skinfold measurement. The BMI may be superior to the PI as the association between BMI and cardiovascular risk factors is less affected by gender.

Selected body composition methods can be used in field studies

This article provides an overview of the present status of in vivo body composition methodologies that have potential for use in field studies. The methods are divided into four general categories: anthropometric indices and skinfold, body volume measurements, body water measurements including bioelectrical methods, and imaging techniques. Among the newest technologies are air-displacement plethysmography, three-dimensional photonic scanning, multifrequency bioelectrical impedance spectroscopy and whole-body tomography using electrical impedance and magnetic induction. These newer approaches are compared with the established reference methods. The advantages and limitations of each technique as a field method are presented relative to the corresponding concepts of an ideal method.

Defining health-related obesity in prepubertal children

OBJECTIVE

The purpose of this study was to develop percentage of fat and waist circumference cut-points in prepubertal children with the intention of defining obesity associated with cardiovascular disease (CVD) risk.

RESEARCH METHODS AND PROCEDURES

A cross-sectional analysis of 87 prepubertal children aged 4 to 11 years was used. Percentage of body fat was determined by DXA. Waist circumference was measured to the nearest millimeter. Receiver Operating Characteristic analyses of percentage of fat and waist circumference were used to develop cut-points for individuals with adverse levels of CVD risk factors.

RESULTS

The risk factors selected for analyses (i.e., fasting insulin, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and total cholesterol/high-density lipoprotein cholesterol) were significantly related to percentage of body fat and waist circumference. Likelihood ratios were used to identify percentage of fat and waist circumference cut-points associated with adverse cardiovascular risk profiles. Two cut-points, an upper cut-point of 33% body fat and a lower cut-point of 20% body fat, were derived. Waist circumference cut-points indicative of adverse and normal risk-factor profiles were 71 cm and 61 cm, respectively.

DISCUSSION

The data indicate that children with > or =33% body fat and children with a waist circumference > or =71 cm were more likely to possess an adverse CVD risk-factor profile than a normal risk-factor profile. The likelihood of children with < 20% body fat or a waist circumference < 61 cm possessing an adverse CVD risk-factor profile as opposed to a normal risk-factor profile was small. The cut-points describe an adequate health-related definition of childhood obesity.

Metabolic precursors and effects of obesity in children: a decade of progress, 1990-1999

Current data suggest that 20% of US children are overweight. An analysis of secular trends suggested a clear upward trend in body weight in children of 0.2 kg/y between 1973 and 1994. In addition, childhood obesity is more prevalent among minority subgroups, such as African Americans. Obesity that begins early in life persists into adulthood and increases the risk of obesity-related conditions later in life. Obesity is now considered a disease of epidemic proportions, not just in the United States but also worldwide. In the past 10 y there has been a tremendous increase in the number of studies examining the etiology and health effects of obesity in children. The major objectives of this article are to 1) review highlights in pediatric obesity research from 1990 to 1999; 2) summarize our research on the roles of energy expenditure, physical activity, and aerobic capacity in the etiology of pediatric obesity, and on ethnic differences in the relation between obesity and type 2 diabetes risk factors in children; and 3) discuss areas of future study that will require greater emphasis as the field of childhood obesity research evolves over future years.