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

Changes in Anthropometric Measurements, Body Composition, and Blood Pressure in 6-10-Year-Old Children with Overweight and Obesity in Szczecin During a Year-Long Intervention Program

Background: The growing problem of excess body weight in children is currently one of the most important public health threats. Methods: The aim of this study was to assess the impact of a year-long intervention on the body composition and blood pressure of 6-10-year-old children with excess body weight in the city of Szczecin. This study was divided into two parts: stage I was a cross-sectional population-based study (screening in schools) while stage II was an interventional study with before/after comparison. Results: A total of 4890 children participated in the first stage, while 515 children qualified for the second stage. During each visit in the intervention stage, anthropometric measurement (height, body weight), body composition analysis using bioelectrical impedance (body fat mass in kilograms, percentage of body fat, muscle mass in kilograms, fat-free mass), and blood pressure measurement were performed. This study did not record a significant effect of the year-long intervention on changes in the blood pressure percentiles of the children. However, there was a significant increase in the number of children with a normal percentage of body fat (92.64% vs. 96.92%) and a significant increase in muscle mass in the majority of children (96.30%, p < 0.0001). The body fat percentage, body fat mass, and muscle mass measurements differed between children who were overweight and those who were obese. The average percentage (girls 27.80 ± 2.72 vs. 24.61 ± 3.04; p < 0.0001, boys 20.93 ± 4.51 vs. 16.02 ± 1.83; p < 0.0001) and mass of body fat (girls 12.12 ± 2.82 vs. 9.44 ± 1.46; p = 0.0001, boys 9.73 ± 3.72 vs. 6.16 ± 1.31; p = 0.0001), as well as the average muscle mass (31.01 ± 4.6 vs. 26.8 ± 4.08; p < 0.0001), were higher in children with obesity compared to those with overweight. Conclusions: Further research is necessary to evaluate the effectiveness of therapeutic programs focused on treating excess body weight in children.

Validation of Bioelectrical Impedance Devices for the Determination of Body Fat Percentage in Firefighters

ABSTRACT

Jagim, AR, Luedke, J, Erickson, JL, Fields, JB, and Jones, MT. Validation of bioelectrical impedance devices for the determination of body fat percentage in firefighters. J Strength Cond Res 38(8): e448-e453, 2024-To cross-validate bioelectrical impedance devices for the determination of body fat percentage (BF%) in firefighters. Twenty-eight structural firefighters were evaluated (female, n = 2; male, n = 26 [mean ± SD] age: 38.2 ± 8.3 years; height: 180.2 ± 7.5 cm; body mass: 86.7 ± 20.8 kg; body mass index: 25.8 ± 7.8 kg·m-2) using multifrequency bioelectrical impedance analysis (MFBIA) hand-to-foot device, and single-frequency BIA foot scale (F2FBIA), and a single-frequency handheld BIA device (HHBIA). Dual X-ray absorptiometry served as the criterion. Validity metrics were examined to establish each method's performance. Body fat % values produced by MFBIA (r = 0.913), F2FBIA (r = 0.695), and HHBIA (r = 0.876) were strongly associated (p < 0.001) with criterion BF% measures. However, MFBIA, F2FBIA, and HHBIA all significantly (p < 0.001) underestimated BF% when compared with the criterion measure. Constant error ranged between 4.0 and 5.5% across all BIA devices. Despite strong associations between the BIA devices included in the current study and the criterion measure, all BIA devices underestimated BF%, which resulted in an overestimation of fat-free mass. In addition, proportional bias was observed in which BF% was overestimated at lower values and underestimated at higher values.

Leptin Increase During Dexamethasone and Its Association With Hunger and Fat in Pediatric Acute Lymphoblastic Leukemia

CONTEXT

During treatment, children with acute lymphoblastic leukemia (ALL) receive high doses dexamethasone, which induce acute side effects.

OBJECTIVE

To determine the influence of a 5-day dexamethasone course on changes in leptin, fat mass, BMI, hunger, sleep, and fatigue and to explore associations between these changes.

METHODS

Pediatric ALL patients were included during maintenance treatment. Data were collected before (T1) and after (T2) a 5-day dexamethasone course (6 mg/m2/day). At both time points, BMI, fat mass (bioelectrical impedance analysis), and leptin were assessed, as well as parent-reported questionnaires regarding hunger, fatigue, and sleep problems. Changes between T1 and T2 were assessed using paired tests. Correlation coefficients were calculated to assess associations between these changes (Delta scores: T2-T1). Univariable regression models were estimated to study associations between covariates and elevated leptin.

RESULTS

We included 105 children, with median age 5.4 years (range, 3.0-18.8). Leptin and fat mass, as well as hunger scores, fatigue, and sleep deteriorated after 5 days of dexamethasone (P < .001), in contrast to BMI (P = .12). No correlations between delta leptin and delta fat mass, BMI, hunger, fatigue, or sleep were found. Elevated leptin on T1 was associated with older age (odds ratio [OR] 1.51; 95% CI, 1.28-1.77), higher fat mass (OR 1.19; 95% CI, 1.07-1.33), and earlier maintenance week (OR 0.96; 95% CI, 0.92-0.99).

CONCLUSION

Five days of high-dose dexamethasone treatment led to direct and significant changes in leptin, hunger scores, and fat mass. Since children with ALL are at increased risk for metabolic adverse events, understanding underlying mechanisms is important, and a dexamethasone-induced state of acute leptin resistance might play a role.

Does incorporating high intensity interval training in physical education classes improve fitness outcomes of students? A cluster randomized controlled trial

The aim of this study was to determine the efficacy of a high intensity interval training (HIIT) intervention lasting 12 weeks on fitness (cardiorespiratory fitness, muscular strength, muscular endurance, power, speed, flexibility, and balance) and adiposity of 10- to 15-year-old students implemented during their physical education (PE). The focus of this study was to compare two approaches to increasing fitness level among school-aged children, one approach focusing on regular PE sessions in accordance with the curriculum and another one on regular PE classes augmented by HIIT. A cluster-randomized controlled trial was conducted (February-May 2022, Zagreb, Croatia). The total number of students across both groups was 207. General linear models were used to compare fitness and adiposity changes in both groups based on Eurofit test battery. A significant effect of the HIIT intervention was present for the 20-meter shuttle run test (p = 0.001; d = 0.31). The effect of the intervention compared to the control was estimated as an additional 181.2 m, 95 %CI (70.4 to 292.0). An additional intention-to-treat (ITT) analysis showed that the effect of the HIIT intervention on 20-meter shuttle run test remained statistically significant (p = 0.011), though the magnitude of the estimated effect was reduced from 181.2 m; SE = 55.4 to 119.6 m; SE = 46.4. Whilst it appears HIIT had the opposite of the expected effect on body fat percentiles, the effect on body composition was inconsistent. The intervention is registered at the Australian New Zealand Clinical Trials Registry (ANZCTR) [ACTRN12622000209796].

Differences in Body Composition Analysis by DEXA, Skinfold and BIA Methods in Young Football Players

The most widely used method in professional sports for fat percentage assessment is the skinfold method. However, there is the chance of bias and human error. For this reason, other more precise methods are used, such as single-frequency bioelectrical impedance analysis (BIA) or dual energy X-ray absorptiometry (DEXA). However, there are limited data that demonstrate the methodological shortcomings or congruences in fat and fat-free mass estimates including gender differences and differences in athlete populations. Thus, the aim of the present study was to compare total body fat (%BF) estimated by six skinfold thickness measurement (SKF) and single-frequency bioelectrical impedance analysis (BIA) methods, using three different sets of equations, to that assessed by the dual energy X-ray absorptiometry (DEXA) method using a DEXA Hologic Serie Discovery QDR. For this aim, 76 males and 70 females belonging to the professional Spanish football federation were evaluated. We found significant differences between the three measures. BIA significantly underestimates the fat percentage, followed by skinfolds. With DEXA being the more objective or accurate method, an equation is established by means of linear regression analysis that allows the percentage of adipose tissue to be obtained either through anthropometry or electrical bioimpedance and adjusted to that which would be obtained by the DEXA system.

Association of electrical bioimpedance vectors with the nutritional classification of vulnerable multiethnic children

BACKGROUND & AIMS

Monitoring growth and body composition in childhood is vital for early detection of health and nutrition problems during child development. The bioelectrical impedance vector analysis (BIVA) revealed its effectiveness as an indicator of nutritional status. This study aimed to measure the bioimpedance vectors of a sample of multiethnic children and evaluate the utility of BIVA for the classification of the nutritional status in a group of children with greater vulnerability, including in the presence of obesity.

METHODS

This is a cross-sectional study that analyzed the bioelectrical impedance of a sample of 321 children from public daycare centers, aged 1-4 years, using the RXc graph method (tetrapolar analysis at 50 kHz frequency). The 95%, 75%, and 50% tolerance ellipses were plotted by age group. The Z-scores of bioimpedance parameters (Xc/H-Z and R/H-Z) were calculated regarding age, which were used to build reference tolerance ellipses for a single group, regardless of age. Such ellipses were evaluated for their ability to recognize the pattern and classify the deviations, using individual vectors of obese children.

RESULTS

The mean impedance vectors showed progressively higher reactances and lower resistances with age. In the group of obese children, the individual vectors located outside the 95% baseline tolerance ellipse were 12.5%, 18.75%, and 11.1% of the cases for the WHZ, WAZ, and BMIZ criteria, respectively, all above the expected 5%, but much below expectations. This may be a problem with the obesity criteria used, as WHZ, WAZ, and BMIZ do not differentiate fat from lean mass.

CONCLUSION

Bioimpedance vector analysis reflects differences in the bioelectric patterns of children classified as obese. Provided the obesity criteria are constructed based on fat measurements, rather than lean mass, the use of tolerance ellipses in the BIVA chart is promising as a tool for monitoring nutritional status where measuring body composition is difficult, because constant tissue hydration cannot be assumed.

Comparison of bioelectrical impedance analysis, mass index, and waist circumference in assessing risk for non-alcoholic steatohepatitis

OBJECTIVE

Non-alcoholic fatty liver disease is a leading cause of liver disease worldwide and includes nonalcoholic steatohepatitis (NASH), which can progress to cirrhosis. Because NASH is associated with obesity severity, routine evaluation of obesity/body fat in clinical settings may help detect patients at risk. The aim of this study was to determine whether assessing body fat by bioelectrical impedance analysis (BIA) is superior to body mass index (BMI) and waist circumference (WC) in assessing the risk for NASH.

METHODS

In this cross-sectional study, patients were recruited and gave consent from a local hospital. All had a liver biopsy. Measurements before the biopsy included BMI, WC, and BIA. BIA was used to measure percentage body fat and fat mass (kg). Based on histology, patients were grouped into one of three categories: simple steatosis (SS), NASH, or normal liver (NL).

RESULTS

Of the 139 participants who participated, 39 were classified as SS, 53 as NASH, and 47 as NL. Regardless of sex, patients with NASH had significantly higher BMI, WC, percentage body fat and fat mass than those with NL or SS. These four parameters were significantly positively correlated with liver histology measurements. In all patients, when controlling for sex and age we found that BMI, WC, and BIA were equal at predicting the presence of NASH (P = 0.0571).

CONCLUSION

All three methods, BIA, BMI, and WC, were comparable in assessing the risk for NASH. For practical purpose in clinical settings, using BMI is acceptable.

Concordance between Body Composition Indices Measured with Dual-Energy X-Ray Absorptiometry and Bioelectrical Impedance Analysis in Obese Children in Sri Lanka

Dual-energy X-ray absorptiometry (DXA) is the reference standard in the measurement of body composition indices. But, its utility is limited due to the high cost, expertise required, lack of portability, and restricted availability. Therefore, bioelectrical impedance analysis (BIA) has gained recognition in resource-limited settings for the measurement of body composition indices in the screening of children for childhood obesity. To determine whether BIA represents a viable alternative to DXA in the assessment of body composition in obese children in the community setting in Sri Lanka, the concordance between BIA and DXA was determined. Fat mass (FM), percentage fat mass (%FM), and fat-free mass (FFM) were measured in 97 obese children using DXA and BIA, and the concordance between the methods was analyzed using independent sample t-test, regression analysis, and Bland-Altman plots. Significant mean differences were observed between DXA and BIA in measuring FM and FFM. However, high correlations were seen in DXA- and BMI-derived FM and FFM measurements (FM r = 0.92 and FFM 0.83, P < 0.001 for both). Compared to DXA, BIA overestimated FM and %FM and underestimated FFM. When compared with DXA-derived measurements, the accuracy errors (SEE) of BIA for FM, FFM, and %FM were relatively higher in boys (3.56 kg, 4.49 kg, and 5.46%, respectively) than in girls (2.44 kg, 3.72 kg, and 3.5%), respectively. BA plots showed a systematic error in the measurements of FM, FFM, and %FM in both sexes. Despite the limitations inherited, BIA is a viable alternative to DXA for the measurement of body composition in obese children of 5-15 yrs. The accuracy errors observed, however, need to be taken into consideration when interpreting results at the individual level.

Validation of bioelectrical impedance analysis for body composition assessment in children with obesity aged 8-14y

BACKGROUND & AIMS

The aim was to generate a predictive equation to assess body composition (BC) in children with obesity using bioimpedance (BIA), and avoid bias produced by different density levels of fat free mass (FFM) in this population.

METHODS

This was a cross-sectional validation study using baseline data from a randomized intervention trial to treat childhood obesity. Participants were 8 to 14y (n = 315), underwent assessments on anthropometry and BC through Air Displacement Plethysmography (ADP), Dual X-Ray Absorptiometry and BIA. They were divided into a training (n = 249) and a testing subset (n = 66). In addition, the testing subset underwent a total body water assessment using deuterium dilution, and thus obtained results for the 4-compartment model (4C). A new equation to estimate FFM was created from the BIA outputs by comparison to a validated model of ADP adjusted by FFM density in the training subset. The equation was validated against 4C in the testing subset. As reference, the outputs from the BIA device were also compared to 4C.

RESULTS

The predictive equation reduced the bias from the BIA outputs from 14.1% (95%CI: 12.7, 15.4) to 4.6% (95%CI: 3.8, 5.4) for FFM and from 18.4% (95%CI: 16.9, 19.9) to 6.4% (95% CI: 5.3, 7.4) for FM. Bland-Altman plots revealed that the new equation significantly improved the agreement with 4C; furthermore, the observed trend to increase the degree of bias with increasing FM and FFM also disappeared.

CONCLUSION

The new predictive equation increases the precision of BC assessment using BIA in children with obesity.

Assessment of body composition in pediatric overweight and obesity: A systematic review of the reliability and validity of common techniques

Accurate measurement of body composition is required to improve health outcomes in children and adolescents with overweight or obesity. This systematic review aimed to summarize the reliability and validity of field and laboratory body composition techniques employed in pediatric obesity studies to facilitate technique selection for research and clinical practice implementation. A systematic search in MEDLINE (via PubMed), EMBASE, CINAHL, and SPORTDiscus from inception up to December 2019 was conducted, using a combination of the following concepts: body composition, pediatric overweight/obesity, and reliability/validity. The search strategy resulted in 66 eligible articles reporting reliability (19.7%), agreement between body composition techniques cross sectionally (80.3%), and/or diagnostic test accuracy (10.6%) in children and adolescents with overweight or obesity (mean age range = 7.0-16.5 years). Skinfolds, air-displacement plethysmography (ADP), dual-energy X-ray absorptiometry (DXA), and ultrasound presented as reliable techniques. DXA, ADP, and isotope dilution showed similar and the best agreement with reference standards. Compared with these laboratory techniques, the validity of estimating body composition by anthropometric equations, skinfolds, and BIA was inferior. In conclusion, the assessment of body composition by laboratory techniques cannot be replaced by field techniques due to introduction of measurement errors, which potentially conceal actual changes in body components.

Children and Adolescents' Anthropometrics Body Composition from 3-D Optical Surface Scans

OBJECTIVE

This study aimed to explore the accuracy and precision of three-dimensional optical (3DO) whole-body scanning for automated anthropometry and estimating total and regional body composition.

METHODS

Healthy children and adolescents (n = 181, ages 5-17 years) were recruited for the Shape Up! Kids study. Each participant underwent whole-body dual-energy x-ray absorptiometry and 3DO scans; multisite conventional tape measurements served as the anthropometric criterion measure. 3DO body shape was described using automated body circumference, length, and volume measures. 3DO estimates were compared with criterion measures using simple linear regression by the stepwise selection method.

RESULTS

Of the 181 participants, 112 were used for the training set, 49 were used for the test set, and 20 were excluded for technical reasons. 3DO body composition estimates were strongly associated with dual-energy x-ray absorptiometry measures for percent body fat, fat mass, and fat-free mass (R2 : 0.83, 0.96, and 0.98, respectively). 3DO provided reliable measurements of fat mass (coefficient of variation, 3.30; root mean square error [RMSE], 0.53), fat-free mass (coefficient of variation, 1.34; RMSE, 0.53 kg), and percent body fat (RMSE = 1.2%).

CONCLUSIONS

3DO surface scanning provides accurate and precise anthropometric and body composition estimates in children and adolescents with high precision. 3DO is a safe, accessible, and practical method for evaluating body shape and composition in research and clinical settings.

Rationale and design of the school-based SI! Program to face obesity and promote health among Spanish adolescents: A cluster-randomized controlled trial

Unhealthy habits in adolescents are increasing at an alarming rate. The school offers a promising environment in which to implement effective preventive strategies to improve adolescents' lifestyle behaviors. The SI! Program is a multilevel multicomponent school-based health-promotion intervention aimed at all stages of compulsory education in Spain. We present the study design of the SI! Program for Secondary Schools, targeting adolescents aged 12 to 16 years.

AIM

The main goal of this study is to evaluate the impact of the SI! Program educational intervention on adolescent lifestyle behaviors and health parameters.

METHODS

The study was designed as a cluster-randomized controlled intervention trial and enrolled 1326 adolescents from 24 public secondary schools in Spain, together with their parents/caregivers. Schools and their students were randomly assigned to the intervention group (the SI! curriculum-based educational program over 2 or 4 academic years) or to the control group (usual curriculum). The primary endpoint will be the change from baseline at 2-year and 4-year follow-up in the composite Ideal Cardiovascular Health (ICH) score, consisting of four health behaviors (body mass index, dietary habits, physical activity, and smoking) and three health factors (blood pressure, total cholesterol, and glucose). Secondary endpoints will include 2-year and 4-year changes from baseline in ICH score subcomponents, the Fuster-BEWAT health scale, adiposity markers (waist circumference and body composition), polyphenol and carotenoid intake, and emotion management.

DISCUSSION

The overarching goal of the SI! Program is to instill healthy behaviors in children and adolescents that can be sustained into adulthood. The SI! Program for Secondary School is a comprehensive health-promotion intervention targeting 12-16-year-old adolescents and their immediate environment. The present study addresses the optimal timing and impact of the educational intervention on health in adolescence.

The Use of a Stem and Leaf Aqueous Extract of Cissus quadrangularis (CQR-300) to Reduce Body Fat and Other Components of Metabolic Syndrome in Overweight Participants

BACKGROUND

Previous work had shown the ability of an aqueous leaf and stem extract of Cissus quandrangularis (300 mg of CQR, CQR-300) to improve components of metabolic syndrome (MS) in overweight individuals.

OBJECTIVE

This small pilot study aimed to confirm the efficacy of CQR-300 in reducing the percentage body fat measured using two different methods-bioelectrical impedance assay versus dual-energy X-ray absorptiometry (DEXA).

DESIGN

The study was an 8-week double-blind, placebo-controlled pilot trial on 67 individuals who were requested by a dietary counselor to maintain their normal exercise and dietary routines. Participants were randomly divided into two groups, placebo (32 participants) and the CQR-300 group (35 participants), and received 300 mg of corn starch or CQR-300 daily.

METHODS

Body fat was measured by bioelectrical impedance using a TANITA impedance meter and by DEXA, with blood samples taken at baseline and at 8 weeks for the measurement of lipid parameters.

RESULTS

After 8 weeks of treatment, participants of the placebo group showed a 1.05% decrease in body fat as determined by bioelectrical impedance analysis, but no difference using DEXA. In the same time period, the CQR-300 group had an 8.9% and 12.8% decreases in the body fat as measured by impedance and DEXA, respectively. These values were significantly (p < 0.05) lower than the placebo. Compared with the placebo, the CQR-300 group demonstrated significant (p < 0.05) decreases in the waist and hip circumferences, systolic and diastolic blood pressures, total cholesterol, triglycerides, fasting blood glucose, as well as leptin levels. On the contrary, there were significant (p < 0.05) increases in HDL-cholesterol and adiponectin levels.

CONCLUSION

CQR-300 administered as a single 300 mg dose daily was effective in reducing body fat as well as improving blood parameters associated with MS.

Comparison of Bioelectrical Impedance Analysis, Slaughter Skinfold-Thickness Equations, and Dual-Energy X-ray Absorptiometry for Estimating Body Fat Percentage in Colombian Children and Adolescents with Excess of Adiposity

Dual-energy X-ray absorptiometry (DXA) has been considered a reference method for measuring body fat percentage (BF%) in children and adolescents with an excess of adiposity. However, given that the DXA technique is impractical for routine field use, there is a need to investigate other methods that can accurately determine BF%. We studied the accuracy of bioelectrical impedance analysis (BIA) technology, including foot-to-foot and hand-to-foot impedance, and Slaughter skinfold-thickness equations in the measurement of BF%, compared with DXA, in a population of Latin American children and adolescents with an excess of adiposity. A total of 127 children and adolescents (11–17 years of age; 70% girls) from the HEPAFIT (Exercise Training and Hepatic Metabolism in Overweight/Obese Adolescent) study were included in the present work. BF% was measured on the same day using two BIA analysers (Seca^® 206, Allers Hamburg, Germany and Model Tanita^® BC-418^®, TANITA Corporation, Sportlife Tokyo, Japan), skinfold measurements (Slaughter equation), and DXA (Hologic Horizon DXA System^®, Quirugil, Bogotá, Columbia). Agreement between measurements was analysed using t-tests, Bland–Altman plots, and Lin’s concordance correlation coefficient (ρc). There was a significant correlation between DXA and the other BF% measurement methods (r > 0.430). According to paired t-tests, in both sexes, BF% assessed by BIA analysers or Slaughter equations differ from BF% assessed by DXA (p < 0.001). The lower and upper limits of the differences compared with DXA were 6.3–22.9, 2.2–2.8, and −3.2–21.3 (95% CI) in boys and 2.3–14.8, 2.4–20.1, and 3.9–18.3 (95% CI) in girls for Seca^® mBCA, Tanita^® BC 420MA, and Slaughter equations, respectively. Concordance was poor between DXA and the other methods of measuring BF% (ρc < 0.5). BIA analysers and Slaughter equations underestimated BF% measurements compared to DXA, so they are not interchangeable methods for assessing BF% in Latin American children and adolescents with excess of adiposity.

Validity of electrical impedance myography to estimate percent body fat: comparison to bio-electrical impedance and dual-energy X-ray absorptiometry

BACKGROUND

Assessment of percent body fat (%BF) is typically measured with bioelectrical impedance (BIA) as a proxy for dual-energy X-ray absorptiometry (DXA). Notably, poorer agreement between BIA and DXA among persons who are overweight or obese has been reported. The use of electrical impedance myography (EIM) as a proxy for DXA has not been validated. The objective was to evaluate an EIM device and two multi-frequency BIA devices with the reference standard (DXA) stratified by weight status and gender.

METHODS

In a convenience sample of 82 adults, %BF assessed by EIM and two BIA devices was compared to DXA. Agreement between devices was tested with intra-class correlation coefficients (ICC) and Bland-Altman plots.

RESULTS

Agreement between DXA and EIM (ICC=0.77) was poorer than the agreement between either BIA device with DXA (ICC>0.87). Stratified by sex, agreement between EIM and DXA was greater for men than women (ICC=0.81 and ICC=0.61, respectively). Stratified by BMI, agreement between EIM and DXA was best for normal-weight individuals (ICC=0.89) and progressively poorer for overweight (ICC=0.80) and obese (ICC=0.67) individuals. Bland-Altman plots revealed wide limits of agreement and an increase in EIM mean difference as average %BF increased. Similar trends were seen in BIA assessments.

CONCLUSIONS

EIM and BIA substantially underestimate %BF in overweight and obese individuals. Wide limits of agreement coupled with variable ICC limit device interchangeability with one another and limit clinical utility.

Sarcopenic obesity and cognitive performance

BACKGROUND

Sarcopenia and obesity both negatively impact health including cognitive function. Their coexistence, however, can pose an even higher threat likely surpassing their individual effects. We assessed the relationship of sarcopenic obesity with performance on global- and subdomain-specific tests of cognition.

PATIENTS AND METHODS

The study was a cross-sectional analysis of data from a series of community-based aging and memory studies. The sample consisted of a total of 353 participants with an average age of 69 years with a clinic visit and valid cognitive (eg, Montreal Cognitive Assessment, animal naming), functional (eg, grip strength, chair stands), and body composition (eg, muscle mass, body mass index, percent body fat) measurements.

RESULTS

Sarcopenic obesity was associated with the lowest performance on global cognition (Est.Definition1=-2.85±1.38, p=0.039), followed by sarcopenia (Est.Definition1=-1.88±0.79, p=0.017) and obesity (Est.Definition1=-1.10±0.81, p=0.175) adjusted for sociodemographic factors. The latter, however, did not differ significantly from the comparison group consisting of older adults with neither sarcopenia nor obesity. Subdomain-specific analyses revealed executive function (Est.Definition1=-1.22±0.46 for sarcopenic obesity; Est.Definition1=-0.76±0.26 for sarcopenia; Est.Definition1=-0.52±0.27 for obesity all at p<0.05) and orientation (Est.Definition1=0.59±0.26 for sarcopenic obesity; Est.Definition1=-0.36±0.15 for sarcopenia; Est.Definition1=-0.29±0.15 all but obesity significant at p<0.05) as the individual cognitive skills likely to be impacted. Potential age-specific and depression effects are discussed.

CONCLUSION

Sarcopenia alone and in combination with sarcopenic obesity can be used in clinical practice as indicators of probable cognitive impairment. At-risk older adults may benefit from programs addressing loss of cognitive function by maintaining/improving strength and preventing obesity.

Body Fat Measurements in Singaporean Adults Using Four Methods

Few studies have been conducted to measure body composition in Asian populations. In this study, we determined the percent body fat (PBF) by using dual-energy X-ray absorptiometry (DEXA), air-displacement plethysmography (ADP or BOD POD), bioelectrical impedance analysis (BIA) and skinfold (SKF) in 445 healthy Singaporean adults. We observed that the BOD POD, BIA and SKF estimates of PBF were highly correlated with that from DEXA (as a reference method) among Singaporean adults. However, they all underestimated PBF (differences of 3.9% for BOD POD, 5.6% for BIA and 12.5% for SKF). Our results filled a gap in the literature by testing the relationships between DEXA and BOD POD, BIA and SKF in a large sample with a wide range of body mass index (BMI) from 16.1 to 37.5 kg/m² and age from 21 to 69.2 years. The differences of PBF measured by different methods were dependent on age, gender and ethnicity. No significant difference was observed between DEXA and BOD POD in men aged > 40 or in BMI tertile 3. However, the mean difference between DEXA and BOD POD was significant in women. Different measuring methods of estimating PBF therefore must be cautiously interpreted.

The Obesity Factor: How Cardiorespiratory Fitness is Estimated More Accurately in People with Obesity

OBJECTIVE

Cardiopulmonary exercise testing is clinically used to estimate cardiorespiratory fitness (CRF). The relation to total body mass (TBM) leads to an underestimation of CRF in people with obesity and to inappropriate prognostic and therapeutic decisions. This study aimed to determine body composition-derived bias in the estimation of CRF in people with obesity.

METHODS

Two hundred eleven participants (58.8% women; mean BMI 35.7 kg/m² [± 6.94; 20.7-58.6]) were clinically examined, and body composition (InBody720; InBody Co., Ltd., Seoul, South Korea) and spiroergometrical peak oxygen consumption (VO₂ peak) were assessed. The impacts of TBM, lean body mass (LBM), and skeletal muscle mass (SMM) on CRF estimates were analyzed by the application of respective weight models. Linear regression and plotting of residuals against BMI were performed on the whole study population and two subgroups (BMI < 30 kg/m² and BMI ≥ 30 kg/m² ).

RESULTS

For every weight model, Δmean VO₂ peak (expected - measured) was positive. LBM and SMM had a considerable impact on VO₂ peak demand (P = 0.001; ΔR²  = 2.3%; adjusted R²  = 56% and P = 0.001; ΔR² = 2.7%; adjusted R²  = 56%), whereas TBM did not. Confounding of body composition on VO₂ peak did not differ in LBM and SMM.

CONCLUSIONS

TBM-adjusted overestimation of relative VO₂ demand is much higher in people with obesity than in those without. LBM or SMM adjustment may be superior alternatives, although small residual body composition-derived bias remains.

Limitations of body mass index to assess body composition due to sarcopenic obesity during leukemia therapy

Obesity as defined by body mass index percentile (BMI%) is strongly associated with relapse and poorer survival in childhood ALL. Whether BMI% accurately reflects body fat percentage (BF%) in this population is unknown. We conducted a prospective study assessing body composition during frontline ALL therapy. Dual-energy X-ray absorptiometry measured BF% and lean muscle mass (LMM) at diagnosis, end of Induction, and end of Delayed Intensification. Sarcopenic obesity (gain in BF% with loss of LMM) was surprisingly common during ALL treatment, resulting in poor correlation between changes in BMI% (expressed as Z-score) and BF% overall (r = -0.05) and within patients (r = -0.09). BMI Z-score and BF% changed in opposite directions in >50% of interval assessments. While BMI% at diagnosis is a suitable predictor of obesity/BF% for epidemiological studies, change in BMI% (as expressed as Z-score) does not reflect body composition. Studies evaluating obesity in leukemia should consider using direct measures of body composition.

Validity of segmental bioelectrical impedance analysis for estimating fat-free mass in children including overweight individuals

This study examined the validity of segmental bioelectrical impedance (BI) analysis for predicting the fat-free masses (FFMs) of whole-body and body segments in children including overweight individuals. The FFM and impedance (Z) values of arms, trunk, legs, and whole body were determined using a dual-energy X-ray absorptiometry and segmental BI analyses, respectively, in 149 boys and girls aged 6 to 12 years, who were divided into model-development (n = 74), cross-validation (n = 35), and overweight (n = 40) groups. Simple regression analysis was applied to (length)²/Z (BI index) for each of the whole-body and 3 segments to develop the prediction equations of the measured FFM of the related body part. In the model-development group, the BI index of each of the 3 segments and whole body was significantly correlated to the measured FFM (R² = 0.867-0.932, standard error of estimation = 0.18-1.44 kg (5.9%-8.7%)). There was no significant difference between the measured and predicted FFM values without systematic error. The application of each equation derived in the model-development group to the cross-validation and overweight groups did not produce significant differences between the measured and predicted FFM values and systematic errors, with an exception that the arm FFM in the overweight group was overestimated. Segmental bioelectrical impedance analysis is useful for predicting the FFM of each of whole-body and body segments in children including overweight individuals, although the application for estimating arm FFM in overweight individuals requires a certain modification.

Low-glycemic index diet may improve insulin sensitivity in obese children

BACKGROUND

A low-glycemic index (GI) diet may be beneficial for weight management due to its effect on insulin metabolism and satiety.

METHODS

Obese children aged 9-16 y were randomly assigned either a low-GI diet or a low-fat diet (control group) for 6 mo. Body composition changes were measured by dual-energy X-ray absorptiometry and bioelectrical impedance analysis. Insulin sensitivity was measured by fasting plasma glucose and insulin.

RESULTS

Fifty-two participants completed the study (mean age: 12.0 ± 2.0 y, 35 boys); both groups showed significantly decreased BMI z-score but similar changes in fat and fat-free mass. The low-GI group demonstrated a significant decline in fasting plasma insulin (22.2 ± 14.3 to 13.7 ± 10.9 mU/l; P = 0.004) and homeostatic model of assessment-insulin resistance (4.8 ± 3.3 to 2.9 ± 2.3; P = 0.007), whereas the control group did not. However, general linear model showed no significant difference in insulin resistance between groups after adjusting for baseline levels, suggesting that the greater reduction in insulin resistance in the low-GI group may be explained by higher baseline values.

CONCLUSION

Despite subtle effects on body composition, a low-GI diet may improve insulin sensitivity in obese children with high baseline insulin. A bigger study in obese children with insulin resistance could be worthwhile to confirm our findings.

Fat-free mass prediction equations for bioelectric impedance analysis compared to dual energy X-ray absorptiometry in obese adolescents: a validation study

Background

In clinical practice, patient friendly methods to assess body composition in obese adolescents are needed. Therefore, the bioelectrical impedance analysis (BIA) related fat-free mass (FFM) prediction equations (FFM-BIA) were evaluated in obese adolescents (age 11–18 years) compared to FFM measured by dual-energy x-ray absorptiometry (FFM-DXA) and a new population specific FFM-BIA equation is developed.

Methods

After an overnight fast, the subjects attended the outpatient clinic. After measuring height and weight, a full body scan by dual-energy x-ray absorptiometry (DXA) and a BIA measurement was performed. Thirteen predictive FFM-BIA equations based on weight, height, age, resistance, reactance and/or impedance were systematically selected and compared to FFM-DXA. Accuracy of FFM-BIA equations was evaluated by the percentage adolescents predicted within 5 % of FFM-DXA measured, the mean percentage difference between predicted and measured values (bias) and the Root Mean Squared prediction Error (RMSE). Multiple linear regression was conducted to develop a new BIA equation.

Results

Validation was based on 103 adolescents (60 % girls), age 14.5 (sd1.7) years, weight 94.1 (sd15.6) kg and FFM-DXA of 56.1 (sd9.8) kg. The percentage accurate estimations varied between equations from 0 to 68 %; bias ranged from −29.3 to +36.3 % and RMSE ranged from 2.8 to 12.4 kg. An alternative prediction equation was developed: FFM = 0.527 * H(cm)²/Imp + 0.306 * weight - 1.862 (R² = 0.92, SEE = 2.85 kg). Percentage accurate prediction was 76 %.

Conclusions

Compared to DXA, the Gray equation underestimated the FFM with 0.4 kg (55.7 ± 8.3), had an RMSE of 3.2 kg, 63 % accurate prediction and the smallest bias of (−0.1 %). When split by sex, the Gray equation had the narrowest range in accurate predictions, bias, and RMSE. For the assessment of FFM with BIA, the Gray-FFM equation appears to be the most accurate, but 63 % is still not at an acceptable accuracy level for obese adolescents. The new equation appears to be appropriate but await further validation. DXA measurement remains the method of choice for FFM in obese adolescents.

Trial registration

Netherlands Trial Register (ISRCTN27626398).

Malnutrition in cirrhosis increases morbidity and mortality

BACKGROUND AND AIMS

Malnutrition is frequent in patients with cirrhosis and is associated with complications like ascites, hepatic encephalopathy, infections, and death. We determined the prevalence of malnutrition by various methods and its clinical importance in patients with cirrhosis.

METHODS

Consecutive patients of cirrhosis from August 2013 to February 2015 were assessed. Nutritional status was assessed by traditional model (mid-arm circumference, triceps skinfold thickness, serum albumin, creatinine height index, total lymphocyte count), handgrip, and body composition analysis measuring skeletal muscle mass and body fat mass. All patients were followed up for 12 months to assess the outcome.

RESULTS

247 patients (age 42.10 ± 10.14 years, 81% male) were included in the study. Etiology of cirrhosis was alcohol in 53% patients. Prevalence of malnutrition was 59.5% according to traditional model, 66.8% by body composition analysis and 71.4% by handgrip. Nutritional status was poor in alcoholic cirrhotics versus nonalcoholics as assessed by triceps skinfold thickness (9.33 ± 2.9 vs 11.64 ± 3.5 mm; P = 0.001), serum albumin (25.1 ± 4 vs 28.1 ± 4 g/L; P = 0.001), and body fat mass (7.6 ± 3.1 vs 8.7 ± 3.3 kg; P = 0.008). Prevalence of malnutrition was 12/27 (44.5%), 96/131 (73.3%) and 84/89 (94.4%) in Child's class A, B, and C respectively. Complications requiring hospitalization (71.3% vs 38.2%; 0.002) and mortality (41.1% vs 18.2%; P = 0.001) were more in malnourished patients compared to well nourished. Nutritional assessment parameters significantly correlated with the liver disease severity (P < 0.05).

CONCLUSIONS

Prevalence of malnutrition is high in patients with cirrhosis. It is associated with increased complications and mortality.

Comparação de três equações para predição da gordura corporal por bioimpedância em jovens obesas

INTRODUÇÃO: A impedância bioelétrica (BIA) tem sido bastante utilizada para o monitoramento da composição corporal em indivíduos de diferentes idades e estados nutricionais. Entretanto, não se sabe qual das equações propostas para crianças e adolescentes é a mais recomendada para utilização em adolescentes com excesso de peso. Objetivo: Verificar a concordância dos métodos de BIA usando três equações diferentes com a absorciometria de raio-X de dupla energia (DXA), para análise da composição corporal de adolescentes com sobrepeso e obesidade.MÉTODOS: Participaram do estudo 27 adolescentes do sexo feminino, com sobrepeso e obesidade. Foram avaliados o percentual de gordura corporal (%GC), a massa gorda (MG) e a massa livre de gordura (MLG) por DXA e por BIA utilizando as equações propostas por Houtkooper, Schaefer e Deurenberg. ANOVA oneway, gráficos de Bland-Altman e o coeficiente de correlação intraclasse foram utilizados para comparação e verificação da concordância entre os métodos.RESULTADOS: A BIA utilizando a equação proposta por Houtkooper foi a única que não apresentou diferença estatística significativa na estimativa de %GC, MG e MLG em comparação ao DXA e apresentou boa concordância com o DXA na estimativa de %GC (-1,9 ± 3,29%), MG (1,5 ± 2,59 kg) e MLG (1,4 ± 2,60 kg), bem como boa reprodutibilidade para %GC (CCI = 0,81), MG (0,96) e MLG (0,89). As equações de Schaefer e de Deurenberg apresentaram menor concordância com o DXA, superestimando a MG e subestimando a MLG e apresentaram reprodutibilidade de moderada a baixa na maioria das medidas da composição corporal.CONCLUSÃO: Quando comparamos as três equações propostas para BIA com o DXA, verificamos que a equação proposta por Houtkooper foi a que melhor concordou com DXA e apresentou boa reprodutibilidade para estimar %GC, MG e MLG em adolescentes com sobrepeso e obesidade.

Bioelectrical impedance as a measure of change in body composition in young children

BACKGROUND AND OBJECTIVES

The ability of bioelectrical impedance (BIA) to measure change in body composition in children has rarely been examined.

METHODS

Body composition was estimated by BIA (Tanita BC-418) and dual-energy x-ray absorptiometry (DXA) in 187 children aged 4-8 years at baseline and at 12 months. Change in body composition was compared between the two methods using mixed models.

RESULTS

Estimates of change in fat mass did not differ between BIA and DXA for overweight girls (mean difference between methods, 95% confidence interval: 0.04 kg, -0.19 to 0.28) or boys (0.07 kg, -0.14 to 0.27). BIA was also able to accurately detect change in fat-free mass, with no significant differences between methods (-0.14 kg, -0.10 to 0.38 in girls and -0.07 kg, -0.35 to -0.20 in boys). Change in percentage fat produced similar estimates in both genders (0.18%, -0.82 to 0.46 in girls and 0.38%, -0.37 to 1.13 in boys). BIA/DXA comparisons in normal weight children were also not significantly different, with the exception of percentage fat in girls, where BIA slightly underestimated change compared with DXA (0.7%, 0.02-0.37).

CONCLUSION

BIA performed well as a measure of change in body composition, providing confidence for its use as an outcome measure in children.

24 h Accelerometry: impact of sleep-screening methods on estimates of sedentary behaviour and physical activity while awake

Although accelerometers can assess sleep and activity over 24 h, sleep data must be removed before physical activity and sedentary time can be examined appropriately. We compared the effect of 6 different sleep-scoring rules on physical activity and sedentary time. Activity and sleep were obtained by accelerometry (ActiGraph GT3X) over 7 days in 291 children (51.3% overweight or obese) aged 4-8.9 years. Three methods removed sleep using individualised time filters and two methods applied standard time filters to remove sleep each day (9 pm-6 am, 12 am-6 am). The final method did not remove sleep but simply defined non-wear as at least 60 min of consecutive zeros over the 24-h period. Different methods of removing sleep from 24-h data markedly affect estimates of sedentary time, yielding values ranging from 556 to 1145 min/day. Estimates of non-wear time (33-193 min), wear time (736-1337 min) and counts per minute (384-658) also showed considerable variation. By contrast, estimates of moderate-to-vigorous activity (MVPA) were similar, varying by less than 1 min/day. Different scoring methods to remove sleep from 24-h accelerometry data do not affect measures of MVPA, whereas estimates of counts per minute and sedentary time depend considerably on which technique is used.

Dietary fibre and health in children and adolescents

The role of dietary fibre in promoting sustained health has been studied for several decades and in adults there is good evidence that diets rich in high-fibre foods reduce the risk of chronic diseases, including CVD and cancer. Research in this area, however, has been hampered by uncertainties about the definition of dietary fibre which has resulted in many studies measuring fibre in different ways. There is also a wide range of properties and actions of different fibres in the human body, depending on their solubility, viscosity and fermentability by the colonic microbiota. This review considers the epidemiological evidence for dietary fibre and health in children and the current dietary recommendations and measured intakes in several countries using national surveys. In children and adolescents, there is a particular lack of relevant research on which to formulate appropriate dietary fibre recommendations and these are often based on extrapolation from adult data. However, children are not little adults and have differing physiology and nutritional needs as they grow. The dietary recommendations in different countries are based on varying premises and daily amounts. Intakes vary from country to country and on the whole do not meet recommendations. Much more research is needed in children to fully understand the impact of dietary fibre on growth and health in the young to allow more appropriate recommendations to be made.

Systematic review to identify and appraise outcome measures used to evaluate childhood obesity treatment interventions (CoOR): evidence of purpose, application, validity, reliability and sensitivity

BACKGROUND

Lack of uniformity in outcome measures used in evaluations of childhood obesity treatment interventions can impede the ability to assess effectiveness and limits comparisons across trials.

OBJECTIVE

To identify and appraise outcome measures to produce a framework of recommended measures for use in evaluations of childhood obesity treatment interventions.

DATA SOURCES

Eleven electronic databases were searched between August and December 2011, including MEDLINE; MEDLINE In-Process and Other Non-Indexed Citations; EMBASE; PsycINFO; Health Management Information Consortium (HMIC); Allied and Complementary Medicine Database (AMED); Global Health, Maternity and Infant Care (all Ovid); Cumulative Index to Nursing and Allied Health Literature (CINAHL) (EBSCOhost); Science Citation Index (SCI) [Web of Science (WoS)]; and The Cochrane Library (Wiley) - from the date of inception, with no language restrictions. This was supported by review of relevant grey literature and trial databases.

REVIEW METHODS

Two searches were conducted to identify (1) outcome measures and corresponding citations used in published childhood obesity treatment evaluations and (2) manuscripts describing the development and/or evaluation of the outcome measures used in the childhood intervention obesity evaluations. Search 1 search strategy (review of trials) was modelled on elements of a review by Luttikhuis et al. (Oude Luttikhuis H, Baur L, Jansen H, Shrewsbury VA, O'Malley C, Stolk RP, et al. Interventions for treating obesity in children. Cochrane Database Syst Rev 2009;1:CD001872). Search 2 strategy (methodology papers) was built on Terwee et al.'s search filter (Terwee CB, Jansma EP, Riphagen II, de Vet HCW. Development of a methodological PubMed search filter for finding studies on measurement properties of measurement instruments. Qual Life Res 2009;18:1115-23). Eligible papers were appraised for quality initially by the internal project team. This was followed by an external appraisal by expert collaborators in order to agree which outcome measures should be recommended for the Childhood obesity Outcomes Review (CoOR) outcome measures framework.

RESULTS

Three hundred and seventy-nine manuscripts describing 180 outcome measures met eligibility criteria. Appraisal of these resulted in the recommendation of 36 measures for the CoOR outcome measures framework. Recommended primary outcome measures were body mass index (BMI) and dual-energy X-ray absorptiometry (DXA). Experts did not advocate any self-reported measures where objective measurement was possible (e.g. physical activity). Physiological outcomes hold potential to be primary outcomes, as they are indicators of cardiovascular health, but without evidence of what constitutes a minimally importance difference they have remained as secondary outcomes (although the corresponding lack of evidence for BMI and DXA is acknowledged). No preference-based quality-of-life measures were identified that would enable economic evaluation via calculation of quality-adjusted life-years. Few measures reported evaluating responsiveness.

LIMITATIONS

Proposed recommended measures are fit for use as outcome measures within studies that evaluate childhood obesity treatment evaluations specifically. These may or may not be suitable for other study designs, and some excluded measures may be more suitable in other study designs.

CONCLUSIONS

The CoOR outcome measures framework provides clear guidance of recommended primary and secondary outcome measures. This will enhance comparability between treatment evaluations and ensure that appropriate measures are being used. Where possible, future work should focus on modification and evaluation of existing measures rather than development of tools de nova. In addition, it is recommended that a similar outcome measures framework is produced to support evaluation of adult obesity programmes.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

A critical evaluation of bioimpedance spectroscopy analysis in estimating body composition during GH treatment: comparison with bromide dilution and dual X-ray absorptiometry

OBJECTIVE

To compare estimates by bioimpedance spectroscopy analysis (BIS) of extracellular water (ECW), fat mass (FM), and fat-free mass (FFM) against standard techniques of bromide dilution and dual energy X-ray absorptiometry (DXA) during intervention that causes significant changes in water compartments and body composition.

METHODS

Body composition analysis using BIS, bromide dilution, and DXA was performed in 71 healthy recreational athletes (43 men, 28 women; aged 18-40 years; BMI 24 ± 0.4 kg/m(2)) who participated in a double-blinded, randomized, placebo-controlled study of GH and testosterone treatment. The comparison of BIS with bromide dilution and DXA was analyzed using linear regression and the Bland-Altman method.

RESULTS

At baseline, there was a significant correlation between BIS and bromide dilution-derived estimates for ECW, and DXA for FM and FFM (P<0.001). ECW by BIS was 3.5 ± 8.1% lower compared with bromide dilution, while FM was 22.4 ± 26.8% lower and FFM 13.7 ± 7.5% higher compared with DXA (P<0.01). During treatment, the change in ECW was similar between BIS and bromide dilution, whereas BIS gave a significantly greater reduction in FM (19.4 ± 44.8%) and a greater increase in FFM (5.6 ± 3.0%) compared with DXA (P<0.01). Significant differences in body composition estimates between the BIS and DXA were observed only in men, particularly during the treatment that caused greatest change in water compartments and body composition.

CONCLUSION

In healthy adults, bioimpedance spectroscopy is an acceptable tool for measuring ECW; however, BIS overestimates FFM and substantially underestimates FM compared with DXA.

The four-compartment model of body composition in obese Chilean schoolchildren, by pubertal stage: comparison with simpler models

OBJECTIVES

We assessed the agreement of body fat and fat-free mass measured by simpler methods against the four-compartment model (4C).

METHODS

In 60 obese schoolchildren (body mass index ≥95th percentile) between the ages of 8 and 13 y who were recruited from one school in Chile, multicompartmental body composition was estimated with the use of isotopic dilution, plethysmography (BodPod), radiographic absorptiometry (DEXA), and anthropometric equations. These results were compared to those of the 4C model, which is considered the gold standard.

RESULTS

For body fat, the 4C model showed the best agreement with DEXA for boys in Tanner stages I and II (r = 0.971) and with isotopic dilution for boys in Tanner stages III and IV (r = 0.984). The best agreement in girls occurred with isotopic dilution, regardless of pubertal stage (r = 0.948 for Tanner stages I and II; r = 0.978 for Tanner stages III and IV). Both isotopic dilution and the Huang, Ellis, and Deurenberg anthropometric equations underestimated body fat in boys; by contrast, DEXA, BodPod, and the Slaughter equation overestimated body fat in boys. All of the equations underestimated body fat in girls. For fat-free mass in both boys and girls, the 4C model showed the best agreement with isotopic dilution, regardless of pubertal stage. The Huang equation showed the best agreement for boys (r = 0.730 for Tanner stages I and II; r = 0.695 for Tanner stages III and IV) and for girls in Tanner stages I and II (r = 0.884). The Ellis equation had the best agreement for girls in Tanner stages III and IV (r = 0.917).

CONCLUSIONS

For obese Chilean children of both sexes, isotopic dilution and DEXA were the two-compartment methods that had the best agreement with the gold-standard 4C model for both body fat and fat-free mass; these were followed by the Huang and Ellis anthropometric equations.

Food prices and body fatness among youths

We examine the effect of food prices on clinical measures of obesity, including body mass index (BMI) and percentage body fat (PBF) measures derived from bioelectrical impedance analysis (BIA) and dual energy X-ray absorptiometry (DXA), among youths ages 12 through 18 in the National Health and Nutrition Examination Survey. This is the first study to consider clinically measured levels of body composition rather than BMI to investigate the effects of food prices on obesity outcomes among youths classified by gender and race/ethnicity. Our findings suggest that increases in the real price per calorie of food for home consumption and the real price of fast-food restaurant food lead to improvements in obesity outcomes among youths. We also find that a rise in the real price of fruits and vegetables leads to increased obesity. Finally, our results indicate that measures of PBF derived from BIA and DXA are no less sensitive and in some cases more sensitive to the prices just mentioned than BMI, and serve an important role in demonstrating that rising food prices (except fruit and vegetable prices) are indeed associated with reductions in obesity rather than with reductions in body size proportions alone.

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.

Lower limb body composition is associated to knee passive extension torque-angle response

PURPOSE

People vary in flexibility regarding maximum joint angle, resistance to stretch and mechanical responses during stretching exercises. Body composition (BC) has been been mentioned as one of the factors for flexibility differences. The aim of this study was to determine how body composition and anthropometric measures of the lower limb is associated with passive knee extension (PKE) torque-angle (T-A) response.

METHODS

Twenty-five male subjects with poor flexibility performed a maximal PKE repetition (velocity of 2°/s; 90 seconds in the static phase). Knee passive T-A, vastus medialis and semitendinosous electromyographic activity were recorded during the protocol. Viscoelastic stress relaxation (VSR) amplitude, knee passive stiffness (KPS), lower limb body composition assessed by dual energy x-ray absorptiometry, and anthropometry measures were determined.

RESULTS

Thigh skeletal muscle and bone mass, as well as thigh perimeter, showed a moderated correlation with passive torque (r = 0.45; r = 0.6; r = 0.59, respectively), joint angle (r = 0.46; r = 0.5; r = 0.5), and VSR (r = 0.46; r = 0.49; r = 0.5). Thigh skeletal muscle was also correlated with KPS (r = 0.42). All these correlations were statistically significant (p < 0.05).

CONCLUSIONS

Passive knee extension T-A was found to be moderately correlated with lower limb BC. In particular, thigh perimeter and skeletal muscle mass were associated with knee passive stiffness and viscoelastic stress relaxation. More research is needed to understand what influences joint maximum angle, resistance to stretch and mechanical response to stretching.

Correlations among adiposity measures in school-aged children

BACKGROUND

Given that it is not feasible to use dual x-ray absorptiometry (DXA) or other reference methods to measure adiposity in all pediatric clinical and research settings, it is important to identify reasonable alternatives. Therefore, we sought to determine the extent to which other adiposity measures were correlated with DXA fat mass in school-aged children.

METHODS

In 1110 children aged 6.5-10.9 years in the pre-birth cohort Project Viva, we calculated Spearman correlation coefficients between DXA (n=875) and other adiposity measures including body mass index (BMI), skinfold thickness, circumferences, and bioimpedance. We also computed correlations between lean body mass measures.

RESULTS

50.0% of the children were female and 36.5% were non-white. Mean (SD) BMI was 17.2 (3.1) and total fat mass by DXA was 7.5 (3.9) kg. DXA total fat mass was highly correlated with BMI (r(s)=0.83), bioimpedance total fat (r(s)=0.87), and sum of skinfolds (r(s)=0.90), and DXA trunk fat was highly correlated with waist circumference (r(s)=0.79). Correlations of BMI with other adiposity indices were high, e.g., with waist circumference (r(s)=0.86) and sum of subscapular plus triceps skinfolds (r(s)=0.79). DXA fat-free mass and bioimpedance fat-free mass were highly correlated (r(s)=0.94).

CONCLUSIONS

In school-aged children, BMI, sum of skinfolds, and other adiposity measures were strongly correlated with DXA fat mass. Although these measurement methods have limitations, BMI and skinfolds are adequate surrogate measures of relative adiposity in children when DXA is not practical.

Measuring body composition in individuals with intellectual disability: a scoping review

BACKGROUND

Research shows obesity to be more prevalent amongst individuals with intellectual disability (ID) making correct measurement of body composition crucial. This study reviewed the validity and reliability of methods used for assessing body composition in individuals with ID.

METHODS

Authors conducted electronic searches through PubMed (1990 to present) and PsycINFO (1990 to present) and assessed relevant articles independently based on scoping review guidelines. Reviewers included primary research related to the validity and reliability of body composition measures on individuals with ID.

RESULTS

Searches identified six articles assessing body composition methods used on individuals with ID including body mass index (BMI), skinfold thickness, bioelectrical impedance analysis (BIA), waist circumference, tibia length, and anthropometric girth measurements. BMI and waist circumference appear suitable measures but skinfold thickness measurements may not be advisable due to participants' noncompliance resulting in a lack of precision and inaccurate results.

CONCLUSIONS

The current literature contains too few well-conducted studies to determine the precision and validity of body composition measures on individuals with ID. There may be a need to devise further regression equations that apply to individuals with specific types of ID in order to increase the reliability and validity of body composition measurements.

Validity assessment of a portable bioimpedance scale to estimate body fat percentage in white and African-American children and adolescents

OBJECTIVE

The objective of the study was to determine accuracy of the Tanita SC-240 body composition analyser to measure paediatric percent body fat (%BF).

METHODS

Eighty-nine African-American and white 5-18-year-olds participated in this study. %BF was estimated by dual-energy X-ray absorptiometry (DXA) and by the Tanita SC-240.

RESULTS

Overall %BF was 33.5 ± 10.5% (Tanita SC-240) vs. 34.5 ± 8.7% (DXA). There was no significant difference between the two measures (P = 0.52, average error = -1.0%, average absolute error = 3.9%). The Tanita mean %BF estimates significantly differed from the DXA mean %BF in white boys (P = 0.001, Cohen's d = 0.40) and white girls (P = 0.006, Cohen's d = 0.48), but differences were of small effect. No differences in %BF estimates were found for African-American boys or girls.

CONCLUSIONS

In this sample, the Tanita SC-240 demonstrated acceptable accuracy for estimating %BF when compared with DXA, supporting its use in field studies.

Fat mass and fat-free mass as indicators of body composition among Bengalee Muslim children

BACKGROUND

The composition of fat mass (FM) and fat-free mass (FFM) are now considered to be important indicators of body composition.

AIM

This cross-sectional study determines the body composition using FM and FFM among children.

SUBJECTS AND METHODS

The study was conducted among 1248 children (619 boys; 629 girls) aged 5-12 years and belonging to the Bengalee Muslim population of West Bengal, India. Anthropometric measurements of height, weight, triceps and sub-scapular skin-folds were recorded and body mass index (BMI) calculated. Body composition was assessed using FM and FFM.

RESULTS

The age-specific mean values of FM and FFM ranged from 1.93-3.07 kg (boys) and 1.91-3.62 kg (girls) and from 14.69-23.44 kg (boys) and 14.18-22.87 kg (girls), respectively. Statistically significant sex differences were observed in FM and FFM (p < 0.05). Age- and sex-specific smooth percentile curves were derived for BMI, FM and FFM using the L, M and S modelling approach for further evaluation of body composition.

CONCLUSION

These findings are important for future investigations in the field and in epidemiological and clinical settings so as to accurately identify risk of lower or higher adiposity and body composition using FM and FFM.

Reduction measures and percent body fat in individuals with intellectual disabilities: a scoping review

BACKGROUND

Individuals with intellectual disability (ID) may be more obese and extremely obese than individuals without ID. There remains an on-going debate as to the effectiveness of exercise training in decreasing body fat in different populations.

OBJECTIVE

This scoping review explored the effects of exercise training interventions on percent body fat in individuals with ID.

METHODS

Authors conducted electronic searches through PubMED (1978 to present) and SPORT Discus (1975 to present) and evaluated relevant articles independently based on guidelines for scoping reviews.

RESULTS

Few exercise interventions have targeted changes in percent body fat. Based on the 11 articles identified, exercise interventions appear effective at maintaining fat levels but have been largely unsuccessful at reducing body fat following training. Only 18% of exercise alone studies produced positive changes in body fat outcomes among individuals with ID.

CONCLUSIONS

Greater focus should be placed on the metabolic health of individuals with ID. Results call into question methods used to date. These findings may be a consequence of the minimal attention paid to nutritional status and also a lack of standardized anthropometric methods and acceptable guidelines for categorizing adiposity based on health risk in this population. Further research is needed to promote more effective and sustainable strategies aimed at combating the elevated levels of body fat.

Body composition in subjects with anorexia nervosa: bioelectrical impedance analysis and dual-energy X-ray absorptiometry

OBJECTIVE

To evaluate the applicability and validity of bioelectrical impedance analysis (BIA) compared with dual-energy X-ray absorptiometry (DXA) in a population of girls with restrictive anorexia nervosa (AN).

METHODS

A total of 30 girls (11-19 years old) with AN were enrolled. DXA and BIA (BIA software and the Deurenberg equations) were used to estimate the body composition. The correlation between the methods was assessed by Pearson's correlation coefficient and the Bland-Altman method.

RESULTS

The mean FFM estimates were 33.2 kg (BIA software), 32.8 kg (BIA, Deurenberg equation) and 33.1 kg (DXA). The mean FM values were 5.6 kg (BIA software), 6.2 kg (BIA, Deurenberg equation) and 6.4 kg (DXA). There was a high correlation between the FFM values estimated with the two methods (BIA software vs DXA r=0.917, p<0.001; Deurenberg equation vs DXA r=0.931, p<0.001). For the FFM, the limits of agreement were equal to ±3.34 kg for the BIA software and ±2.96 kg for the Deurenberg equation. For the FM, the limits of agreement were equal to ±4.60 kg for the BIA software and ±3.82 kg for the Deurenberg equation.

CONCLUSION

The results show a good correlation between DXA and BIA. BIA seems to be a valid alternative for epidemiological and clinical evaluations.

Reliability and intermethod agreement for body fat assessment among two field and two laboratory methods in adolescents

To increase knowledge about reliability and intermethods agreement for body fat (BF) is of interest for assessment, interpretation, and comparison purposes. It was aimed to examine intra- and inter-rater reliability, interday variability, and degree of agreement for BF using air-displacement plethysmography (Bod-Pod), dual-energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA), and skinfold measurements in European adolescents. Fifty-four adolescents (25 females) from Zaragoza and 30 (14 females) from Stockholm, aged 13-17 years participated in this study. Two trained raters in each center assessed BF with Bod-Pod, DXA, BIA, and anthropometry (DXA only in Zaragoza). Intermethod agreement and reliability were studied using a 4-way ANOVA for the same rater on the first day and two additional measurements on a second day, one each rater. Technical error of measurement (TEM) and percentage coefficient of reliability (%R) were also reported. No significant intrarater, inter-rater, or interday effect was observed for %BF for any method in either of the cities. In Zaragoza, %BF was significantly different when measured by Bod-Pod and BIA in comparison with anthropometry and DXA (all P < 0.001). The same result was observed in Stockholm (P < 0.001), except that DXA was not measured. Bod-Pod, DXA, BIA, and anthropometry are reliable for %BF repeated assessment within the same day by the same or different raters or in consecutive days by the same rater. Bod-Pod showed close agreement with BIA as did DXA with anthropometry; however, Bod-Pod and BIA presented higher values of %BF than anthropometry and DXA.

Ethnic variation in body composition assessment in a sample of adolescent girls

OBJECTIVE

To compare body composition assessment by bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA) in a multiethnic sample of adolescent girls.

METHOD

Data were from a physical activity intervention study among 254 14-20-year-old sedentary American girls, including 69 whites, 74 blacks, 42 Hispanics, and 69 Asians. Height and weight were objectively measured. Body composition was assessed using a foot-to-foot BIA and a fan-beam DXA. We calculated ethnic-specific estimates of percentage body fat (BF%), fat mass (FM), fat mass index (FMI), fat-free mass (FFM), and fat-free mass index (FFMI) from BIA and DXA. We used Bland-Altman plots to examine ethnic-specific agreement between BIA and DXA, and used linear regression to test whether the BIA-DXA difference varied across the mean.

RESULTS

Compared to DXA, BIA estimates of fat measures (BF%, FM, and FMI) were lower and lean tissue measures (FFM and FFMI) higher. For example, the BIA-estimated BF% was lower than the DXA estimate by between 4.9% (95% CI: -5.9, -3.9) in blacks and 8.7% (-7.0, -5.0) in Asians, with large limits of agreement (-15.4 to -5.4 in blacks and -16.8 to -0.4 in Asians). Regression analysis showed that BIA-DXA differences were not constant across means for any body composition measure among Asians or for any measure except BF% among whites.

CONCLUSION

Compared to DXA, BIA yielded lower estimates of adiposity in a multiethnic adolescent sample. BIA-DXA differences varied by ethnicity, and across mean body composition values for some ethnicities.