BF In Children Research Articles

Estimation of body fat in children with intellectual disability: development and cross-validation of a simple anthropometric method

ObjectivePopulation-level monitoring of body composition requires accurate, biologically-relevant, yet feasible methods for estimating percent body fat (%BF). The aim of this study was to develop and cross-validate an equation for %BF from Body Mass Index (BMI), age, and sex among children with intellectual disability (ID). This study further aimed to examine the performance of an existing BMI-based equation (Deurenberg equation) for %BF in children with ID. MethodParticipants were 107 children (63 boys; aged 6-15 years) with ID randomly allocated to development (n = 81) and cross-validation (n = 26) samples. Dual-Energy X-Ray Absorptiometry provided the criterion %BF. ResultsThe model including BMI, age, and sex (0 = male; 1 = female) had a significant goodness-of-fit in determining %BF (p < 0.001; R2 = 0.69; SEE =5.68%). The equation was: %BF = – 15.416 + (1.394 × BMI) + (4.538 × age) – (0.262 × age2) + (5.489 × sex). The equation was cross-validated in the separate sample based on (i) strong correlation (r = 0.82; p < 0.001) and non-significant differences between actual and predicted %BF (28.6 ± 9.6% and 30.1 ± 7.1%, respectively); (ii) mean absolute error (MAE) = 4.4%; and (iii) reasonable %BF estimations in Bland-Altman plot (mean: 1.48%; 95% CI: 12.5, -9.6). The Deurenberg equation had a large %BF underestimation (mean: -7.1%; 95% CI: 5.3, -19.5), significant difference between actual and estimated %BF (28.6 ± 9.7% and 21.5 ± 7.0%, respectively; p < 0.001), and MAE = 8.1%. ConclusionsThe developed equation with BMI, sex, and age provides valid %BF estimates for facilitating population-level body fat screening among children with ID.

Development of anthropometric equations for predicting total body fat percentage in Chilean children and adolescents

Introduction: studying the percentage of body fat (%BF) in children and adolescents is very relevant, since a high level of body fat in childhood and adolescence represents overweight and obesity. Objective: to identify the anthropometric indicators related to %BF and to validate regression equations to predict %BF in children and adolescents using dual-energy X-ray absorptiometry (DXA) as a reference method. Methods: a descriptive study (cross-sectional) was designed in 1126 schoolchildren (588 males and 538 females) from the Maule region (Chile). The age range ranged from 6.0 to 17.9 years. Weight, height, two skinfolds (tricipital and subscapular and waist circumference (WC) were evaluated. Body mass index (BMI), triponderal mass index (TMI), waist height index (WHtR) were calculated. Body fat percentage (%BF) was assessed by DXA scanning. Results: the relationships between Σ (Tricipital + Subscapular), TMI and WHtR with %BF (DXA) ranged from R2 = 52 % to 54 % in men, and from R2 = 41 % to 49 % in women. The equations generated for men were: %BF = 9.775 + [(0.415 * (Tr + SE)] + (35.084 * WHtR) - (0.828 * age), R2 = 70 %, and %BF = 20.720 + [(0.492 * (Tr + SE)] + (0.354 * TMI) - (0.923 * age), R2 = 68 %], and for women: %BF = 8.608 + [(0.291 * (Tr + SE)] + (38.893 * WHtR) - (0.176 * age), R2 = 60 %, and %BF = 16.087 + [(0.306 * (Tr + SE)] + (0.818 * TMI) - (0.300 * age), R2 = 59 %. Conclusion: this study showed that the sum of tricipital and subscapular skinfolds, IP and WHtR are adequate predictors of %BF. These indicators allowed the development of two regression equations acceptable in terms of precision and accuracy to predict %BF in children and adolescents of both sexes.

Validade e acurácia de equações de predição de gordura corporal usando medidas antropométricas em crianças de 7 a 10 anos

abstract Children with a deficit of growth because of perinatal malnutrition present specificities in the percentage of body fat (%BF) that could not be detected by previous fat mass-based equations. This study developed and validated predictive equations of the %BF derived from anthropometric variables in children aged 7 to 10 living in Northeast Brazil, using dual-energy x-ray absorptiometry (DXA) as a reference. Body composition data from 58 children were utilized. DXA was used as a reference. A stepwise (forward) multiple regression statistical model was used to develop the new equations. The Bland-Altman analysis (CI: 95%), paired Student's t-test, and the intraclass correlation coefficient (ICC) was used to validate and compare the developed equations. Two new equations were developed for either gender: boys: %BF: 13.642 + (1.527*BMI) + (-0.345*Height) + (0.875*Triceps) + (0.290* Waist Circumference) and girls: %BF: -13.445 + (2.061*Tight). The Bland-Altman analysis showed good agreement, with limits ranging from -1.33 to 1.24% for boys and -3.35 to 4.08% for girls. The paired Student’s t-test showed no difference between %BF-DXA and the two new equations (p&gt; 0.05), and the ICC was 0.948 and 0.915, respectively. DXA-based anthropometric equations provide an accurate and noninvasive method to measure changes in the %BF in children.

Validation of two portable bioelectrical impedance analyses for the assessment of body composition in school age children.

BackgroundBioelectrical impedance analysis (BIA) is a convenient and child-friendly method for longitudinal analysis of changes in body composition. However, most validation studies of BIA have been performed on adult Caucasians. The present cross-sectional study investigated the validity of two portable BIA devices, the Inbody 230 (BIA8MF) and the Tanita BC-418 (BIA8SF), in healthy Taiwanese children.MethodsChildren aged 7–12 years (72 boys and 78 girls) were recruited. Body composition was measured by the BIA8SF and the BIA8MF. Dual X-ray absorptiometry (DXA) was used as the reference method.ResultsThere were strong linear correlations in body composition measurements between the BIA8SF and DXA and between the BIA8MF and DXA. Both BIAs underestimated fat mass (FM) and percentage body fat (%BF) relative to DXA in both genders The degree of agreement in lean body mass (LBM), FM, and %BF estimates was higher between BIA8MF and DXA than between BIA8SF and DXA. The Lin’s concordance correlation coefficient (ρc) for LBM8MF met the criteria of substantial to perfect agreement whereas the ρc for FM8MF met the criteria of fair to substantial agreement. Bland-Altman analysis showed a clinically acceptable agreement between LBM measures by BIA8MF and DXA. The limit of agreement in %BF estimation by BIA and DXA were wide and the errors were clinically important. For the estimation of ALM, BIA8SF and BIA8MF both provided poor accuracy.ConclusionsFor all children, LBM measures were precise and accurate using the BIA8MF whereas clinically significant errors occurred in FM and %BF estimates. Both BIAs underestimated FM and %BF in children. Thus, the body composition results obtained using the inbuilt equations of the BIA8SF and BIA8MF should be interpreted with caution, and high quality validation studies for specific subgroups of children are required prior to field research.

Bioelectrical impedance analysis to estimate body composition in children and adolescents: a systematic review and evidence appraisal of validity, responsiveness, reliability and measurement error

Bioelectrical impedance analysis (BIA) is a practical method to estimate percentage body fat (%BF). In this systematic review, we aimed to assess validity, responsiveness, reliability and measurement error of BIA methods in estimating %BF in children and adolescents.We searched for relevant studies in Pubmed, Embase and Cochrane through November 2012. Two reviewers independently screened titles and abstracts for inclusion, extracted data and rated methodological quality of the included studies. We performed a best evidence synthesis to synthesize the results, thereby excluding studies of poor quality. We included 50 published studies. Mean differences between BIA and reference methods (gold standard [criterion validity] and convergent measures of body composition [convergent validity]) were considerable and ranged from negative to positive values, resulting in conflicting evidence for criterion validity. We found strong evidence for a good reliability, i.e. (intra-class) correlations ≥0.82. However, test-retest mean differences ranged from 7.5% to 13.4% of total %BF in the included study samples, indicating considerable measurement error. Our systematic review suggests that BIA is a practical method to estimate %BF in children and adolescents. However, validity and measurement error are not satisfactory.

Does the body adiposity index (BAI) apply to paediatric populations?

Objective: Validation of body adiposity index (BAI) in a paediatrics sample; and to develop, if necessary, a valid BAI for paediatrics (i.e. BAIp).Methods: A total of 1615 children (52% boys) aged 5–12 years underwent anthropometry. Their body composition was assessed using a foot-to-foot bioimpedance. The validity of BAI = (Hip circumference/Height1.5) − 18 was tested by combining correlation and agreement statistics. Then, the sample was split into two sub-samples for the construction of BAIp. A regression was used to compute the prediction equation for BAIp-based percentage of body fat (%BF).Results: The initial BAI over-estimated the %BF of children by 49% (29.6 ± 4.2% versus 19.8 ± 6.8%; p < 0.0001). The original methodology led to a BAIp = (Hip circumference/Height0.8) − 38 in children. When compared to BAI, BAIp showed both better correlation (r = 0.57; p < 0.01 versus r = 0.74; p < 0.0001) and agreement (ICC = 0.34; [95% CI = −0.19–0.65] versus ICC = 0.83; [95% CI = 0.81–0.84]). However, there were some systematic biases between the two values of %BF as exemplified by the large 95% limit of agreement [−9.1%; 8.8%] obtained.Conclusion: BAI over-estimates the %BF in children. In contrast, BAIp appears as a new index for children’s body fatness, with acceptable accuracy. In its current form, this index is valid only for large-scale studies.

Accuracy of prediction equations to assess percentage of body fat in children and adolescents with Down syndrome compared to air displacement plethysmography

To determine the accuracy of the published percentage body fat (%BF) prediction equations (Durnin et al ., Johnston et al ., Brook and Slaughter et al .) from skinfold thickness compared to air displacement plethysmography (ADP) in children and adolescents with Down syndrome (DS). Twenty-eight children and adolescents with DS (10–20 years old; 12 girls, 16 boys) participated in the study. Anthropometric measurements height, weight, and skinfolds biceps, triceps, subscapular and suprailiac were performed following ISAK recommendations. Total body density (TBD) was estimated using three equations and was also measured with ADP; while %BF was calculated from all densities using the Siri equation and from skinfolds using the Slaughter et al . equation. Finally, the agreement between methods was assessed by plotting the results in Bland–Altman graphs. The presence of heteroscedasticity was also examined. Despite the equation of Slaughter et al . had a large 95% limits of agreement, it was the only one without a significant inter-methods difference and without heteroscedasticity. The equation of Slaughter seems to be, from the studied, the most accurate for estimating %BF in children and adolescents with DS.

Agreement Between Body Mass Index and Percent Body Fat In Determining Clinical Cutpoints For Youth

PURPOSE: A major uncertainty in clinical and epidemiological research relates to the level of uniformity between the clinical cutpoints used in conjunction with body mass index (BMI), waist circumference (WC), and percent body fat (%BF). The purpose of this study was to examine the diagnostic performance of BMI and WC in relation to an estimate of %BF in children and adolescents. METHODS: Clinical data on youth (5-18 years old) were obtained from 3 cross-sectional waves (1999-2000, 2001-2002, 2003-2004) of the National Health and Nutrition Examination Survey (n = 8,228). Percent fat was derived from the skinfold thicknesses, stature and body mass were used to calculate BMI, and WC was also measured. Receiver operator characteristic (ROC) analysis was employed to determine optimal cutpoints between the various adiposity indices using previously recommended BMI, WC, and %BF cutoff values. Sex- and ethnicity-specific %BF percentiles were also created and used to explore diagnostic agreement among the aforementioned indices. RESULTS: The optimal %BF values associated with an overweight BMI in boys ranged from 14%-23% across the age range in all ethnicities. The corresponding values for girls were slightly higher and covered a larger range (16%-33%). For both sexes, the 85th BMI percentile corresponded with slightly lower %BF values for black youth. However, at the 95th BMI percentile, the values for boys were almost identical ranging from 17%-28% fat. In girls, the %BF values were lower for blacks than for white or Mexican American girls. CONCLUSIONS: The findings of this study suggest that a single-value %BF cutoff (such as the 25% or 30% thresholds currently used in FITNESSGRAM) is not appropriate for use across the pediatric age range. Instead, using %BF percentiles may improve diagnostic agreement with the current BMI thresholds of overweight and obesity, especially for females. Further, the results indicate that BMI and %BF association is modified by ethnicity. The optimal cutoffs are provided for each adiposity index, based on the sum of sensitivity and specificity.

Validity and reliability of body composition analysers in children and adults

We tested the validity and reliability of the BioSpace InBody 320, Omron and Bod-eComm body composition devices in men and women (n 254; 21-80 years) and boys and girls (n 117; 10-17 years). We analysed percentage body fat (%BF) and compared the results with dual-energy X-ray absorptiometry (DEXA) in adults and compared the results of the InBody with underwater weighing (UW) in children. All body composition devices were correlated (r 0.54-0.97; P< or =0.010) to DEXA except the Bod-eComm in women aged 71-80 years (r 0.54; P=0.106). In girls, the InBody %BF was correlated with UW (r 0.79; P< or =0.010); however, a more moderate correlation (r 0.69; P< or =0.010) existed in boys. Bland-Altman plots indicated that all body composition devices underestimated %BF in adults (1.0-4.8 %) and overestimated %BF in children (0.3-2.3 %). Lastly, independent t tests revealed that the mean %BF assessed by the Bod-eComm in women (aged 51-60 and 71-80 years) and in the Omron (age 18-35 years) were significantly different compared with DEXA (P< or =0.010). In men, the Omron (aged 18-35 years), and the InBody (aged 36-50 years) were significantly different compared with DEXA (P=0.025; P=0.040 respectively). In addition, independent t tests indicated that the InBody mean %BF in girls aged 10-17 years was significantly different from UW (P=0.001). Pearson's correlation analyses demonstrated that the Bod-eComm (men and women) and Omron (women) had significant mean differences compared with the reference criterion; therefore, the %BF output from these two devices should be interpreted with caution. The repeatability of each body composition device was supported by small CV (<3.0 %).

Methodological agreement between two‐compartment body‐composition methods in children

Increases in childhood obesity have emphasized the importance of accurate and accessible body composition assessment, especially in monitoring prevention and treatment efforts. Previous pediatric studies, comparing measures from air-displacement plethysmography (ADP) to dual-energy X-ray absorptiometry (DXA) and anthropometry (ANTH, skinfold measures), were performed in small numbers of children or in children across large age and body-size ranges. The objectives of this study were: 1) to compare body fat percentage (%BF), fat mass (FM), and fat-free mass (FFM) from ADP with DXA and ANTH, to determine the agreement between techniques; 2) to identify factors that influence agreement or lack of agreement; and 3) to determine if the agreement is constant over a range of body fatness. Healthy children (n = 125), 7-10 years old, participating in a longitudinal pediatric bone health study, were evaluated. Body composition was assessed by ADP, DXA, and ANTH to determine %BF, FM, and FFM. ADP underestimated %BF compared to DXA and ANTH by 5.0% and 1.4%, respectively. Agreement between techniques was influenced by body fatness, height, age, and gender (all P < 0.05). Relatively good agreement was observed between ADP and both DXA and ANTH for FM and FFM. In conclusion, the underestimation of %BF by ADP compared to DXA may be of a magnitude that is clinically significant, especially when using %BF in children to confirm a diagnosis of obesity. Further development of body-composition techniques for young children need to account for variability in age, gender, and level of fatness.

Effect of Intermittent Sub-maximal Exercise on Percent Body Fat using LBIA in Children

BACKGROUND: To increase the accuracy of the leg-to-leg bioelectrical impedance analysis (LBIA) measurement, it is recommended that no exercise be performed within 12 hours of the test. Previous research has shown that a maximal bout of lower-body cycle and whole-body treadmill exercise has no significant effect on %BF estimated by LBIA in children. However, children tend to demonstrate daily physical activity patterns that consist of multiple intermittent bouts of sub-maximal effort rather than a single maximal effort. PURPOSE: To determine the effect of intermittent sub-maximal exercise on %BF estimated by LBIA in children. METHODS: Fifty-nine children (29 females; 30 males) mean age 9.0 ± 1.3 years participated in this study. LBIA measured %BF values were obtained immediately before (PRE) and within five minutes after completing (POST) an intermittent exercise protocol consisting of three 8-minute sub-maximal exercise bouts (1.7 mph, 0% grade; 2.5 mph, 0% grade; and 3.4 mph, 0% grade) each separated by a 5-minute seated rest period. RESULTS: The three exercise bouts corresponded to 56%, 61% and 71% of maximal heart rate. No differences in %BF were observed POST in the female (23.1 ±9.9 vs. 21.8 ±9.9%) and male (23.3 ± 10.5 vs. 21.8 ± 10.2 %) children when compared to PRE values. No significant differences were observed for fat mass, fat free mass, total body water, or body weight, POST when compared to PRE values in either group. Significant correlations (p = 0.0001) were observed between PRE and POST %BF in the female (r = 0.997) and male (r = 0.995) subjects. CONCLUSION: These data indicate that intermittent exercise, that may be representative of daily free-form activities in children, will most likely have a limited impact on mean %BF estimates (≤1.5 %BF). As such, compliance with the guideline of no exercise within 12 hours of the test may not be required when using LBIA to assess %BF in children.