Measurement of percentage of body fat in 411 children and adolescents: a comparison of dual-energy X-ray absorptiometry with a four-compartment model

Management of pediatric obesity as a pathway towards kidney transplantation

Obesity is an increasing problem in pediatrics, leading to cardiovascular, metabolic and psychosocial complications. Additionally, for patients with chronic kidney disease (CKD), obesity can lead to CKD progression towards end-stage renal disease (ESRD) needing renal-replacement therapy (RRT). It is well-established that the optimal type of RRT for children with ESRD is kidney transplantation, as it provides significantly better life expectancy and quality of life. Unfortunately, pediatric patients with CKD/ESRD and obesity face barriers getting to kidney transplantation and often remain on dialysis for a long time, which negatively impacts their life expectancy and quality of life. One barrier to kidney transplant is that Body Mass Index (BMI) is still considered by most transplant centers as the main criterion for obesity assessment, although more recent evidence suggests that BMI is not the best measure of adiposity. Clearcut evidence is lacking that obesity has a long-term negative impact upon the graft. Another barrier to transplant can be bias on the part of referring providers that can deter or delay referral to an obesity treatment program. Our article describes the barriers that pediatric obese patients with CKD and ESRD face in their way towards kidney transplantation. In addition, our article encourages pediatric nephrologists to early refer their patients with CKD and ESRD who suffer from obesity to a specialized obesity treatment program and/or bariatric surgery. Our article also describes the treatment options for pediatric patients with CKD and ESRD who suffer from obesity in order to make them eligible for a kidney transplant.

Childhood Obesity: An Updated Review

BACKGROUND

Childhood obesity is an important and serious public health problem worldwide.

OBJECTIVE

This article aims to familiarize physicians with the evaluation, management, and prevention of childhood.

METHODS

A PubMed search was conducted in May, 2021, in Clinical Queries using the key terms "obesity" OR "obese". The search included clinical trials, randomized controlled trials, case-control studies, cohort studies, meta-analyses, observational studies, clinical guidelines, case reports, case series, and reviews. The search was restricted to English literature and children. The information retrieved from the above search was used in the compilation of the present article.

RESULTS

Most obese children have exogenous obesity characterized by a growth rate for height above the 50th percentile, normal intelligence, normal genitalia, and lack of historical or physical evidence of an endocrine abnormality or a congenital syndrome. Obese children are at risk for dyslipidemia, hypertension, diabetes mellitus, non-alcoholic fatty liver disease, obstructive sleep apnea, psychosocial disturbances, impaired quality of life, and shorter life expectancy. The multitude of serious comorbidities necessitates effective treatment modalities. Dietary modification, therapeutic exercise, and behavioral modification are the fundamentals of treatment. Pharmacotherapy and/or bariatric surgery should be considered for obese individuals who do not respond to the above measures and suffer from a serious comorbid condition.

CONCLUSION

Childhood obesity, once established, is often refractory to treatment. Most treatment programs lead to a brief period of weight loss, followed by rapid re-accumulation of the lost weight after the termination of therapy. As such, preventive activity is the key to solving the problem of childhood obesity. Childhood obesity can be prevented by promoting a healthy diet, regular physical activity, and lifestyle modification. Parents should be encouraged to get involved in school and community programs that improve their children's nutritional status and physical activity.

Physical Activity Levels and Adiposity in Ambulant Children and Adolescents With Cerebral Palsy Compared With Their Typically Developing Peers

PURPOSE

This study assessed physical activity (PA) and body composition of ambulatory children and adolescents with cerebral palsy (CP) and their typically developing peers.

METHODS

Participants included youth with CP (ages 8-18 y and Gross Motor Function Classification System [GMFCS] levels I-III) and their typically developing peers. Outcomes included PA (actigraphy) and fat/lean mass index (FMI/LMI; dual-energy X-ray absorptiometry). Statistical analyses included linear mixed effects models with Bonferroni adjustment. Fixed effects were study group (CP and typically developing); random effects were participant clusters (sex and age). Exploratory analyses included association of body composition and PA, GMFCS level, and CP involvement (unilateral and bilateral).

RESULTS

Seventy-eight participants (CP: n = 40, girls: n = 29; GMFCS I: n = 20; GMFCS II: n = 14; GMFCS III: n = 6) met inclusion criteria. Individuals with CP had lower moderate to vigorous PA (MVPA; β = -12.5; 98.3% confidence interval, -22.6 to -2.5 min; P = .004) and lower LMI (β = -1.1; 97.5% confidence interval, -2.1 to -0.0 kg/m2; P = .020). Exploratory analyses indicated increased LMI with greater MVPA (P = .001), reduced MVPA for GMFCS II (P = .005) and III (P = .001), increased sedentary time for GMFCS III (P = .006), and greater fat mass index with unilateral motor impairment (P = .026).

CONCLUSIONS

The findings contribute to the knowledge base of increasing MVPA and LMI deficits with the greater functional impact of CP. Associations of increasing LMI with greater MVPA support efforts targeting enhanced PA participation to promote independent mobility.

Neural underpinnings of threat bias in relation to loss-of-control eating behaviors among adolescent girls with high weight

Introduction

Loss-of-control (LOC) eating, a key feature of binge-eating disorder, may relate attentional bias (AB) to highly salient interpersonal stimuli. The current pilot study used magnetoencephalography (MEG) to explore neural features of AB to socially threatening cues in adolescent girls with and without LOC-eating.

Methods

Girls (12-17 years old) with overweight or obesity (BMI >85th percentile) completed an AB measure on an affective dot-probe AB task during MEG and evoked neural responses to angry or happy (vs. neutral) face cues were captured. A laboratory test meal paradigm measured energy intake and macronutrient consumption patterns.

Results

Girls (N = 34; Mage = 15.5 ± 1.5 years; BMI-z = 1.7 ± 0.4) showed a blunted evoked response to the presentation of angry face compared with neutral face cues in the left dorsolateral prefrontal cortex, a neural region implicated in executive control and regulation processes, during attention deployment (p < 0.01). Compared with those without LOC-eating (N = 21), girls with LOC-eating (N = 13) demonstrated a stronger evoked response to angry faces in the visual cortex during attention deployment (p < 0.001). Visual and cognitive control ROIs had trends suggesting interaction with test meal intake patterns among girls with LOC-eating (ps = 0.01).

Discussion

These findings suggest that girls with overweight or obesity may fail to adaptively engage neural regions implicated in higher-order executive processes. This difficulty may relate to disinhibited eating patterns that could lead to excess weight gain.

Changes in Food Consumption, BMI, and Body Composition in Youth in the US during the COVID-19 Pandemic

Rates of childhood overweight/obesity have risen for decades; however, data show the prevalence increased at a faster rate during the COVID-19 pandemic. Pandemic-associated increases in youth's body mass index (BMI; kg/m2) have been attributed to decreases in reported physical activity; few studies have examined changes in food intake. We therefore examined changes in total energy, nutrient consumption, BMI, BMIz, and adiposity longitudinally over 3 years, comparing healthy youth aged 8-17 years assessed twice prior to the pandemic, to youth seen once before and once during the pandemic. The total energy intake and percent macronutrient consumption were assessed using a standardized, laboratory-based, buffet-style meal. Height and weight were measured and adiposity was collected via dual energy X-ray absorptiometry. Generalized linear model univariate analyses investigated differences between groups. One-hundred-fifteen youth (15.6 + 2.8 years 47.8% female; 54.8% White) from the Washington D.C., Maryland, and Virginia greater metropolitan area participated. In this secondary analysis, neither changes in total energy intake (p = 0.52) nor changes in nutrient consumption were significantly different between the two groups (ps = 0.23-0.83). Likewise, changes in BMI, BMIz, and adiposity (ps = 0.95-0.25) did not differ by group. Further research should investigate food intake and body composition, comparing youth with and without overweight/obesity to better identify those at greatest risk of excess weight gain during the pandemic.

Mechanical effects of obesity on central and peripheral airway resistance in nonasthmatic early pubescent children

BACKGROUND

In children, obesity typically reduces functional residual capacity (FRC), which reduces airway caliber and increases airway resistance. Whether these obesity-related changes in respiratory function can alter bronchodilator responsiveness is unknown.

OBJECTIVE

To investigate bronchodilator responsiveness in nonasthmatic children with and without obesity.

METHODS

Seventy nonasthmatic children, 8-12 years old, without (n = 19) and with (n = 51) obesity, completed spirometry, impulse oscillometry, and airway resistance measurements through plethysmography pre/post 360 µg of inhaled albuterol. FRC was assessed pre albuterol. A two-way analysis of variance determined the effects of obesity (group) and inhaled albuterol (pre-post) on outcome measures.

RESULTS

FRC (%total lung capacity) was 16% lower in children with obesity compared with those without obesity. There was no significant group by pre-post albuterol interaction on any outcome variables. Albuterol inhalation reduced total, central and peripheral airway resistance and increased airway reactance (i.e., less negative) to a similar degree in children with and without obesity. In children with obesity, airway resistance was increased whether measured by impulse oscillometry or plethysmography. However, once airway resistance was adjusted for lung volumes (i.e., specific airway resistance or sRaw ), there were no differences between children with and without obesity. In addition, significant but moderate associations were detected between chest mass and FRC (r = -0.566; p < 0.001), FRC and total airway resistance (i.e., Raw ; r = -0.445; p < 0.001).

CONCLUSIONS

In nonasthmatic early pubescent children, obesity increases total, central, and peripheral respiratory system resistance. However, the added respiratory system resistance and low lung volume breathing with obesity are not sufficient to reduce bronchodilator responsiveness.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL IV

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

Gestational and childhood phthalate exposures and adolescent body composition: The HOME study

BACKGROUND

Early life phthalate exposures may disrupt metabolism but results from human studies are inconsistent and few have examined body composition during adolescence. We investigated associations of gestational and childhood urinary phthalate biomarker concentrations with body composition at age 12 years.

METHODS

We used data from 206 mother-child pairs in a prospective pregnancy and birth cohort enrolled in Cincinnati, OH from 2003 to 2006. We measured nine phthalate metabolites in spot urine samples collected twice from mothers during pregnancy and up to seven times from children at 1, 2, 3, 4, 5, 8, and 12 years. At age 12 years, we assessed fat and lean mass of the whole body and android and gynoid subregions, and visceral fat area with dual x-ray absorptiometry, and calculated android to gynoid %fat ratio and age- and sex-standardized fat and lean mass index z-scores. Using a multiple informant model, we estimated covariate-adjusted associations between urinary phthalate biomarker concentrations at each time period and outcomes at age 12 years. We assessed effect measure modification by child sex using stratified models.

RESULTS

Generally, urinary mono-benzyl phthalate (MBzP) concentrations were modestly associated with lower fat and lean mass. Each 10-fold increase in urinary MBzP concentrations during gestation and at ages 5 and 8 years was associated with a -0.34 (95%CI: -0.72, 0.05), -0.44 (95% CI: -0.83, -0.05), and -0.35 (95% CI: -0.71, 0.00) z-score difference in lean body mass index, respectively. Urinary monoethyl phthalate, mono-(3-carboxypropyl) phthalate, and summed di(2-ethylhexyl) phthalate metabolites were associated with greater lean mass at some exposure periods. Slightly weaker but similar patterns of association were found with other body composition measures; associations did not differ by child sex.

CONCLUSION

While most associations were weak, exposure to certain phthalates during gestation and childhood may be associated with adolescent body composition, particularly lean mass.

Fat-Free Mass Using Bioelectrical Impedance Analysis as an Alternative to Dual-Energy X-Ray Absorptiometry in Calculating Energy Availability in Female Adolescent Athletes

Energy availability (EA) is calculated by subtracting exercise energy expenditure from energy intake, adjusted for fat-free mass (FFM) obtained using accurate methods, such as dual-energy X-ray absorptiometry (DXA). Unlike DXA, the bioelectrical impedance analysis (BIA) is low in cost, simple and easy to carry out. This study aimed to test the concordance between the calculation of EA using FFM values from four BIA predictive equations and FFM obtained using DXA in female adolescent athletes (n = 94), recruited via social media. Paired Student's t test, Wilcoxon test, Lin's concordance correlation coefficient, root mean square error, limits of agreement, and mean absolute percentage error were used to evaluate agreement between the FFM values obtained by the four SF-BIA predictive equations and DXA. Regression linear analysis was used to determine the relation between FFM values obtained using DXA and the BIA predictive equations. Standardized residuals of the FFM and EA were calculated considering DXA values as reference. The most appropriate model for the FFM (limits of agreement = 4.0/-2.6 kg, root mean square error = 1.9 kg, mean absolute percentage error = 4.34%, Lin's concordance correlation coefficient = .926) and EA (limits of agreement = 2.51/4.4 kcal·kg FFM-1·day-1, root mean square error = 1.8 kcal·kg FFM-1·day-1, mean absolute percentage error 4.24%, Lin's concordance correlation coefficient = .992) was the equation with sexual maturity as a variable, while the equation with the greatest age variability was the one with the lowest agreement. FFM-BIA predictive equations can be used to calculate EA of female adolescent athletes. However, the equation should be chosen considering sex, age, and maturation status. In the case of athletes, researchers should use equations developed for this group.

Body Composition Assessment in Mexican Children and Adolescents. Part 1: Comparisons between Skinfold-Thickness, Dual X-ray Absorptiometry, Air-Displacement Plethysmography, Deuterium Oxide Dilution, and Magnetic Resonance Imaging with the 4-C Model

The evaluation of body composition (BC) is relevant in the evaluation of children’s health-disease states. Different methods and devices are used to estimate BC. The availability of methods and the clinical condition of the patient usually defines the ideal approach to be used. In this cross-sectional study, we evaluate the accuracy of different methods to estimate BC in Mexican children and adolescents, using the 4-C model as the reference. In a sample of 288 Mexican children and adolescents, 4-C body composition assessment, skinfold-thickness (SF), dual-energy X-ray absorptiometry (DXA), air displacement plethysmography (ADP), and deuterium dilution (D₂O) were performed, along with MRI in a subsample (52 participants). The analysis of validity was performed by correlation analysis, linear regression, and the Bland–Altman method. All methods analyzed showed strong correlations for FM with 4-C values and between each other; however, DXA and MRI overestimated FM, whereas skinfolds and ADP under-estimated FM. Conclusion: The clinical assessment of BC by means of SF, ADP, DXA, MRI and D₂O correlated well with the 4-C model and between them, providing evidence of their clinical validity and utility. The results from different methods are not interchangeable. Preference between methods may depend on their availability and the specific clinical setting.

Height-adjusted lean body mass and its associations with physical activity and kidney function in pediatric kidney transplantation

BACKGROUND

Although LBM is positively associated with health outcomes, studies assessing determinants for the accrual of ht-LBM, such as physical activity, are limited. This study aimed to assess ht-LBM levels in pediatric kidney transplant recipients and test its association with baseline and contemporaneous variables, including physical activity.

METHODS

A retrospective cross-sectional review was performed on 46 pediatric kidney transplant recipients, and a longitudinal review was performed on a subset of recipients with serial post-transplant (n = 21) and pre/post-transplant (n = 11) ht-LBM measurements. Ht-LBM measurements were obtained using DXA scans.

RESULTS

This cohort was 16.0 (IQR 12.3, 17.7) years old, 56.5% male and 46 ± 45 months post-transplant with a mean ht-LBM of 15.1 ± 2.5 kg/m² . A median ht-LBM increase of 1.6 kg/m² (IQR - 0.1, 2.6 kg/m² ; p < .01) was observed, over 29.2 ± 12.0 months from the earliest post-transplant scan obtained at 46 ± 25 months post-transplant until the most recent post-transplant scan. A 1.7 ± 1.4 kg/m² (p < .01) increase was observed between pre- and post-transplant DXA scans which were taken at 12 ± 11 months pre-transplant and 13 ± 6 months post-transplant, respectively. In separate adjusted models, lower physical activity questionnaire scores (n = 17, beta = 1.55, p = .02), faster rate of estimated glomerular filtration rate decline (beta = 0.05, p < .048) adjusted for annualized change in BSA, and younger age at scan (beta = 0.32, p < .01) were each significant predictors of lower ht-LBM.

CONCLUSIONS

Physical activity and kidney function may influence ht-LBM in the pediatric kidney transplant population.

Association Between Age of Achieving Gross Motor Development Milestones During Infancy and Body Fat Percentage at 6 to 7 Years of Age

OBJECTIVES

The later achievement of gross motor milestones during infancy is associated with adiposity in early childhood. However, the associations between gross motor development and adiposity after entering primary school are unclear. This study examined the associations between the ages at which six gross motor milestones were achieved and adiposity during early school years.

METHODS

This retrospective study was conducted in 2012 and 2013. Data were collected from 225 first-grade primary school children (mean age, 6.9 years; 39% girls). Adiposity was assessed using dual-energy X-ray absorptiometry and expressed as body fat percentage. Data describing the ages of achieving six gross motor milestones (holding head up, sitting, crawling, standing supported, walking supported, and independent walking) were obtained from the Maternal and Child Health Handbooks.

RESULTS

Mean body fat percentage was 21.7%. Multiple linear regression analyses revealed that later ages of achieving crawling (p < .001 [95% confidence interval: 0.33-1.16]), standing supported (p < .001 [95% confidence interval: 0.64-1.65]), and walking supported [p = .013 (95% confidence interval: 0.13-1.07)] were associated with increased fat. However, the ages of achieving holding head up (p = .053), sitting (p = .175), and independent walking (p = .736) were not statistically significant.

CONCLUSIONS

Achieving crawling, standing supported, and walking supported later predict increased body fat when aged 6-7 years. The practice of observing gross motor milestone achievements may allow early targeted interventions to optimize body composition before beginning school and thereby, potentially prevent childhood obesity.

Reference values of fat mass index and fat-free mass index in healthy Spanish adolescents

Introduction

Introduction: body mass index (BMI) does not allow to discriminate the composition of the different body compartments. The aim of this study was to develop reference values for the fat mass index (FMI) and fat-free mass index (FFMI) in healthy adolescents using anthropometric techniques in order to provide reference standards for daily clinical practice. Methods: a cross-sectional study in 1,040 healthy Caucasian adolescents (470 boys and 570 girls) aged 10.1 to 14.9 years. Weight, height, and skinfold thickness were recorded, and BMI, percentage of total body fat, FMI and FFMI, and FMI and FFMI percentiles were calculated. Results: FFMI and FMI percentiles for healthy adolescents (both sexes) categorized by age are displayed. In boys a significant increase in FFMI is observed, and both the percentage of total body fat and FMI significantly decreased. In contrast, in girls the percentage of body fat mass, FMI, and FFMI significantly increased. Except at 10 years of age, FMI was higher (p < 0.05) in girls at all ages. FFMI was higher (p < 0.05) in boys at all ages. Conclusions: reference values of FMI and FFMI would be a very useful instrument in clinical practice for the diagnosis and, especially, the analysis of body composition changes during the treatment of childhood obesity.

Secondary consequences of juvenile idiopathic arthritis in children and adolescents with knee involvement: physical activity, adiposity, fitness, and functional performance

OBJECTIVE

Secondary consequences of juvenile idiopathic arthritis (JIA) may impact long-term health outcomes. This study examined differences in physical activity, cardiorespiratory fitness, adiposity, and functional performance in children and adolescents with JIA compared to their typically developing (TD) peers.

METHODS

Participants with JIA (n = 32; 10-20 years old) and their TD peers (n = 35) volunteered for assessments of: daily moderate-to-vigorous physical activity (MVPA, body-worn accelerometer); peak oxygen consumption (VO_{2 Peak}, incremental bike test); fat mass index (FMI, dual-energy X-ray absorptiometry); and triple-single-leg-hop (TSLH) distance. Statistical analyses were performed in R using four linear mixed-effect models with Bonferroni adjustment (⍺ = 0.0125). Fixed effects were group, sex, and age. Participant clusters based on sex and age (within 1.5 years) were considered as random effects.

RESULTS

Participants with JIA displayed lower mean daily MVPA than their TD peers [p = 0.006; β (98.75% CI); -21.2 (-40.4 to -2.9) min]. VO_{2 Peak} [p = 0.019; -1.4 (-2.5 to -0.2) ml/kg/min] decreased with age. Females tended to have lower V_{O2 Peak} [p = 0.045; -6.4 (-13.0 to 0.4) ml/kg/min] and greater adiposity [p = 0.071; 1.4 (-0.1 to 3.0) kg/m²] than males.

CONCLUSION

The findings support the need for strategies to promote MVPA participation in children and adolescents with JIA. Sex and age should be considered in research on the consequences of JIA.

Integrating anthropometric and cardiometabolic health methods in stress, early experiences, and development (SEED) science

Within Stress, Early Experiences, and Development (SEED) science, there is a growing body of research demonstrating complex associations not only between stress, development, and psychopathology, but also with chronic disease risk factors. We argue that it is important for SEED researchers to consider including child anthropometric and physical health measures to more comprehensively capture processes of risk and resilience. Broader adoption of harmonized anthropometry and health measures in SEED research will facilitate collaborations, yielding larger datasets for research in high-risk populations, and greater opportunity to replicate existing findings. In this review, we identify optimal anthropometric and cardiometabolic health measurement methods used from infancy through adolescence, including those that are low-burden and inexpensive. Methods covered include: waist, hip, and head circumference, height, length, weight, pubertal development, body composition, blood pressure, arterial stiffness, carotid intima media thickness, and serum measures of cardiometabolic risk and inflammation. We provide resources for SEED researchers to integrate these methods into projects or to better understand these methods when reading the literature as well as where to find collaborators for more in-depth studies incorporating these measures. With broader integration of psychological and physical health measures in SEED research, we can better inform theory and interventions to promote health and resilience in individuals who have experienced early stress.

The Tri-ponderal Mass Index is associated with adiposity in adolescent type 2 diabetes mellitus: a cross-sectional analysis

Pediatric type 2 diabetes mellitus (T2DM) patients are often overweight or obese, yet there are no validated clinical measures of adiposity to stratify cardiometabolic risk in this population. The tri-ponderal mass index (TMI, kg/m³) has recently been reported as a measure of adiposity in children, but there has been no validation of the association of TMI with adiposity in pediatric T2DM. We hypothesized that in children with T2DM, the TMI can serve as a more accurate measure of adiposity when compared to BMI z-score, and that it is associated with components of the metabolic syndrome. This is a cross-sectional secondary data analysis from the Improving Renal Complications in Adolescents with Type 2 Diabetes Through REsearch (iCARE) study (n = 116, age 10.20–17.90 years). Spearman’s correlations and multivariable regression were used in the analyses. When compared to DXA, TMI demonstrated significant correlation with total adiposity versus BMI z-score (TMI r = 0.74, p-value < 0.0001; BMI z-score r = − 0.08, p-value 0.403). In regression analyses, TMI was associated with WHtR (B = 35.54, 95% CI 28.81, 42.27, p-value < 0.0001), MAP dipping (B = 1.73, 95% CI 0.12, 3.33, p-value = 0.035), and HDL (B = − 5.83, 95% CI − 10.13, − 1.54, p-value = 0.008). In conclusion, TMI is associated with adiposity and components of the metabolic syndrome in pediatric T2DM patients.

Growth and Body Composition in PKU Children-A Three-Year Prospective Study Comparing the Effects of L-Amino Acid to Glycomacropeptide Protein Substitutes

Protein quality and quantity are important factors in determining lean body (muscle) mass (LBM). In phenylketonuria (PKU), protein substitutes provide most of the nitrogen, either as amino acids (AA) or glycomacropeptide with supplementary amino acids (CGMP-AA). Body composition and growth are important indicators of long-term health. In a 3-year prospective study comparing the impact of AA and CGMP-AA on body composition and growth in PKU, 48 children were recruited. N = 19 (median age 11.1 years, range 5–15 years) took AA only, n = 16 (median age 7.3 years, range 5–15 years) took a combination of CGMP-AA and AA, (CGMP50) and 13 children (median age 9.2 years, range 5–16 years) took CGMP-AA only (CGMP100). A dual energy X-ray absorptiometry (DXA) scan at enrolment and 36 months measured LBM, % body fat (%BF) and fat mass (FM). Height was measured at enrolment, 12, 24 and 36 months. No correlation or statistically significant differences (after adjusting for age, gender, puberty and phenylalanine blood concentrations) were found between the three groups for LBM, %BF, FM and height. The change in height z scores, (AA 0, CGMP50 +0.4 and CGMP100 +0.7) showed a trend that children in the CGMP100 group were taller, had improved LBM with decreased FM and % BF but this was not statistically significant. There appeared to be no advantage of CGMP-AA compared to AA on body composition after 3-years of follow-up. Although statistically significant differences were not reached, a trend towards improved body composition was observed with CGMP-AA when it provided the entire protein substitute requirement.

Weight-based teasing in youth: Associations with metabolic and inflammatory markers

BACKGROUND

Research among adults suggests that weight stigma is associated with worsened cardiometabolic health. However, these relationships have not been examined among youth.

OBJECTIVE

Assess associations between weight-based teasing (WBT) and metabolic and inflammatory markers among two samples of youth: (1) a non-treatment-seeking sample and (2) a weight loss treatment-seeking sample with obesity.

METHOD

Weight, height, adiposity, waist circumference and blood pressure were measured. Fasting blood samples were collected for metabolic (triglycerides, glucose, high-density lipoprotein cholesterol) and inflammatory analytes (high-sensitivity C-reactive protein in Study 1 and erythrocyte sedimentation rate in both studies). Youths completed the Perception of Teasing Scale, a measure of WBT. Metabolic and inflammatory indices were compared between those with and without teasing, adjusting for demographics and body composition.

RESULTS

Study 1 enrolled 201 non-treatment-seeking youth (M_age = 13.1y; 54.2% female; 44.8% non-Hispanic White; 32.8% with overweight/obesity); 15.4% reported WBT. Study 2 enrolled 111 treatment-seeking adolescents with obesity (M_age = 14.0y; 66.7% female; 37.8% non-Hispanic White); 73.0% reported WBT. Adjusting for covariates, WBT was not associated with cardiometabolic risk factors in either study.

CONCLUSIONS

WBT was not associated with worsened cardiometabolic health. Longitudinal research is needed to elucidate associations between WBT and health in youth.

Inhibitory control and negative affect in relation to food intake among youth

Negative affect and poor inhibitory control are related to disinhibited eating behaviors in youth and may contribute to the development and/or maintenance of obesity. Although few studies have jointly examined these constructs in youth, it has been theorized that poor inhibitory control may be driven by negative affect. If supported, impaired inhibitory control, driven by negative affect, could represent a modifiable neurocognitive treatment target for disinhibited eating. The current study examined whether inhibitory control mediates the relationship between negative affect and eating among youth. Youth (8-17 years) participated in a Food Go/No-Go neurocognitive task to measure inhibitory control as the percentage of commission errors. A composite negative affect score was created from self-report measures of anxiety and depression. A laboratory buffet meal modeled to simulate disinhibited eating was used to measure total and snack food intake. Cross-sectional mediation models with bias-corrected bootstrap confidence intervals (CI) were conducted using negative affect as the independent variable, inhibitory control as the mediator, and intake patterns as dependent variables. One-hundred-eighty-one youths (13.2 ± 2.7y; 55% female; BMIz 0.6 ± 1.0) were studied. Total Go/No-Go commission errors mediated the relationship between negative affect and total intake (95%CI = [0.3, 31.6]), but not snack intake (95%CI = [-2.5, 7.3]). Commission errors for Food-Go blocks significantly mediated the relationship between negative affect and total intake (95%CI = [7.7, 44.4]), but not snack intake (95%CI = [-3.4, 9.5]). Commission errors on Neutral-Go blocks did not significantly mediate any of these relationships. Negative affect may lead to poorer inhibitory control as well as a stronger approach tendency toward food, increasing the likelihood of engaging in disinhibited eating. Future research should determine if, in combination with approaches to reduce negative affect, improved inhibitory control could help prevent overeating in youths with depressive or anxiety symptoms.

Comparison of bioimpedance spectroscopy and dual energy X-ray absorptiometry for assessing body composition changes in obese children during weight loss

BACKGROUND

Obesity and age influence the reliability of dual energy X-ray absorptiometry scanning (DEXA) and bioimpedance spectroscopy (BIS). Both are used in clinical settings, but have not been compared for measurements in obese children. We compared DEXA and BIS for evaluating body composition and inherent changes in obese children before and after a 10-month weight loss programme.

METHODS

DEXA and BIS were used to evaluate 130 patients at baseline and 75 at follow-up. We tested agreement between the two techniques using Bland-Altman plots and proportional bias using Passing-Bablok regressions.

RESULTS

The Bland-Altman plots showed wide agreement limits before and after weight loss and when monitoring longitudinal changes. At baseline, the Passing-Bablok regressions revealed a proportional bias for all body compartments. After significant weight loss no proportional bias was found for fat mass and percentage, although BIS systematically underestimated fat mass by 2.9 kg. Longitudinally, no proportional bias was found in the measured changes of absolute fat, fat-free mass and fat-free percentage between both methods, although BIS systematically underestimated fat and fat-free mass by 2.6 and 0.7 kg, respectively.

CONCLUSION

While BIS and DEXA are not interchangeable at baseline, the agreement between the two improved after significant weight loss. Proportional changes in fat mass, fat-free mass and fat-free percentage were similar for both techniques. BIS is a viable alternative to DEXA for future paediatric obesity studies measuring treatment effect at group levels, but is not superior to DEXA and cannot be used for monitoring individual changes due to wide limits of agreement.

Quantifying childhood fat mass: comparison of a novel height-and-weight-based prediction approach with DXA and bioelectrical impedance

Accurate assessment of childhood adiposity is important both for individuals and populations. We compared fat mass (FM) predictions from a novel prediction model based on height, weight and demographic factors (height–weight equation) with FM from bioelectrical impedance (BIA) and dual-energy X-ray absorptiometry (DXA), using the deuterium dilution method as a reference standard. FM data from all four methods were available for 174 ALSPAC Study participants, seen 2002–2003, aged 11–12-years. FM predictions from the three approaches were compared to the reference standard using; R², calibration (slope and intercept) and root mean square error (RMSE). R² values were high from ‘height–weight equation’ (90%) but lower than from DXA (95%) and BIA (91%). Whilst calibration intercepts from all three approaches were close to the ideal of 0, the calibration slope from the ‘height–weight equation’ (slope = 1.02) was closer to the ideal of 1 than DXA (slope = 0.88) and BIA (slope = 0.87) assessments. The ‘height–weight equation’ provided more accurate individual predictions with a smaller RMSE value (2.6 kg) than BIA (3.1 kg) or DXA (3.4 kg). Predictions from the ‘height–weight equation’ were at least as accurate as DXA and BIA and were based on simpler measurements and open-source equation, emphasising its potential for both individual and population-level FM assessments.

Evaluating body composition in infancy and childhood: A comparison between 4C, QMR, DXA, and ADP

BACKGROUND

Accurate and precise methods to measure of body composition in infancy and childhood are needed.

OBJECTIVES

This study evaluated differences and precision of three methods when compared with the four-compartment (4C) model for estimating fat mass (FM).

METHODS

FM of children (age 14 days to 6 years of age, N = 346) was obtained using quantitative nuclear magnetic resonance (QMR, EchoMRI-AH), air-displacement plethysmography (ADP, PeaPod, less than or equal to 8 kg, BodPod age 6 years or older), and dual-energy X-ray absorptiometry (DXA, Hologic QDR). The 4C model was computed. Correlation, concordance, and Bland-Altman analyses were performed.

RESULTS

In infants, PeaPod had high individual FM accuracy, whereas DXA had high group FM accuracy compared with 4C. In children, DXA had high group and individual FM accuracies compared with 4C. QMR underestimated group FM in infants and children (300 and 510 g, respectively). The instrument FM precision was best for QMR (10 g) followed by BodPod (34 g), PeaPod (38 g), and DXA (45 g).

CONCLUSIONS

In infants, PeaPod was the best method to estimate individual FM whereas DXA was best to estimate group FM. In children, DXA was best to estimate individual and group FM. QMR had the highest instrument precision.

Relative Accuracy of Bioelectrical Impedance Analysis for Assessing Body Composition in Children With Severe Obesity

OBJECTIVES

The accuracy of different bioelectrical impedance analysis (BIA) devices for assessing body composition in children with obesity is unclear. We determined the relative accuracy of 2 BIA devices compared to dual x-ray absorptiometry (DXA) in obese and severely obese children.

METHODS

We measured body composition in a cross-sectional study of 78 obese children by a handheld single frequency tetrapolar BIA device (Omron), a stationary multifrequency octopolar BIA device (InBody 370) and DXA. Intermethod agreement was assessed by intraclass correlations, paired t tests, and Bland-Altman analyses.

RESULTS

Participants (37% female, age 14.8 ± 2.7 years) had mean (±standard deviation) body mass index of 36.7 ± 7.5 kg/m, body fat percentage of 46.4% ± 5.2%, and appendicular lean mass of 22.5 ± 6.0 kg by DXA. Intraclass correlations with DXA for body fat percentage were 0.39 and 0.87 for single frequency tetrapolar and multifrequency octopolar BIA devices, respectively. The single frequency tetrapolar BIA underestimated body fat percentage by 5.5% ± 2.9% (P < 0.0001). Differences between the multifrequency octopolar BIA and DXA for body fat percentage (-1.1% ± 2.8%) and appendicular lean mass (-0.3 ± 1.4 kg) were small, and 95% limits of agreement were approximately ±5%.

CONCLUSIONS

BIA machines vary in relative accuracy in measuring body composition in children who are obese and severely obese. The multifrequency octopolar BIA device accurately estimated body fat percentage and appendicular lean mass relative to DXA and has the advantage of point of care performance.

Quantification of Cardiorespiratory Fitness in Children with Obesity

PURPOSE

Without consideration for the effects of fat mass, there could be an underestimation of cardiorespiratory fitness in children with obesity leading to a clinical diagnosis of deconditioning and resulting in unrealistic training goals and limitation of physical activities. The purpose of this study was to identify methods of quantifying cardiorespiratory fitness that were less influenced by fat mass.

METHODS

Fifty-three children, 27 with obesity (10.9 ± 1.0 yr) and 26 without obesity (11.0 ± 1.0 yr), volunteered for this study. Maximal oxygen uptake, an indicator of cardiorespiratory fitness, was referenced to lean body mass, body mass, and predicted body mass at the 50th and 85th body mass index percentiles.

RESULTS

Children with obesity carried 18 kg more fat mass and 7 kg more lean body mass compared with children without obesity. Cardiorespiratory fitness based on lean body mass, body mass, and predicted body mass at the 85th percentile was lower in children with obesity compared with children without obesity (P < 0.001). Differences in cardiorespiratory fitness based on predicted body mass at the 50th percentile between children with and without obesity did not reach statistical significance (P = 0.84). Fat mass influenced cardiorespiratory fitness least when referenced to lean body mass or predicted body mass at the 50th percentile (R < 0.26) in contrast to when it was referenced to body mass or predicted body mass at the 85th percentile (R > 0.37).

CONCLUSION

Quantifying cardiorespiratory fitness based on lean body mass or predicted body mass at the 50th percentile could be useful for estimating fitness levels in children with obesity.

Effects of the application of a prolonged combined intervention on body composition in adolescents with obesity

BACKGROUND

The aim of this study is to describe the effects of a prolonged dietary-behavioral-physical activity intervention (24 months) on body composition in a group of adolescents with obesity.

METHODS

Longitudinal study in 196 individuals with obesity (86 boys and 110 girls) aged 10.1-14.9 years that completed a prolonged combined intervention (24 months). Values for weight, height, skinfold thickness, waist circumference, BMI, body fat, fat mass index (FMI) and fat-free mass index (FFMI) were registered or calculated. A good response to treatment was reported when a BMI z-score reduction of greater than or equal to 0.5 units of the initial value occurred after 24 month of follow up.

RESULTS

A good response after 24 months of follow-up reached 58.2% (n = 114). In boys with obesity and BMI status improvement, weight z-score, BMI z-score, body fat, and FMI significantly decreased (p < 0.05). In girls with obesity and BMI status improvement, weight z-score, BMI z-score, waist circumference, waist z-score, body fat and FMI significantly decreased (p < 0.05). In both sexes the height and FFMI increased significantly (p < 0.05). The multiple logistic regression analysis showed that girls and younger age were associated with BMI status improvement; concurrently, the place of residence (urban or rural) and degree of obesity were not associated with BMI status improvement.

CONCLUSION

The application of long-term combined strategies in the treatment of childhood obesity seems to be effective. As BMI decreases, a reduction in fat mass is also detected, with evident sexual dimorphism, in the absence of changes in fat-free mass and, consequently, in longitudinal growing.

Predictive anthropometric models of total and truncal body fat in Chilean children

OBJECTIVES

This study aimed to develop predictive anthropometric models for total and truncal body fat in Chilean children using the following anthropometric measurements: weight, height, skinfold thickness, and circumference.

METHODS

This cross-sectional study included 669 Chilean children (12.0 y ± 1.3) in Tanner stage IV from the Growth and Obesity Chilean Cohort Study. Anthropometric measurements and dual-energy X-ray absorptiometry were determined to calculate total and truncal body fat. Prediction models were fitted by linear regression analysis.

RESULTS

The predictive equation for log total body fat (kg) was 0.449 + 0.049 (body mass index in kg/m²) + 0.018 (triceps skinfold in mm) + 0.012 (biceps skinfold in mm) + 0.019 (brachial circumference in cm) + 0.091 (sex: 1 = boy, 2 = girl) + 0.018 (age in y). The predictive equation for log truncal fat (kg) was -2.107 + 0.046 (waist circumference in cm) + 0.010 (subscapular skinfold in mm) + 0.259 (sex: 1 = boy, 2 = girl) + 0.006 (age in y). The test of concordance between the predictive equations of total and truncal body fat with gold standard was r = 0.85 and 0.91, respectively.

CONCLUSIONS

In Chilean children, the high correlation between observed and predicted values enabled us to develop predictive equations for total and truncal body fat for children.

Bioelectrical Impedance Analysis-An Easy Tool for Quantifying Body Composition in Infancy?

There has been increasing interest in understanding body composition in early life and factors that may influence its evolution. While several technologies exist to measure body composition in infancy, the equipment is typically large, and thus not readily portable, is expensive, and requires a qualified operator. Bioelectrical impedance analysis shows promise as an inexpensive, portable, and easy to use tool. Despite the technique being widely used to assess body composition for over 35 years, it has been seldom used in infancy. This may be related to the evolving nature of the fat-free mass compartment during this period. Nonetheless, a number of factors have been identified that may influence bioelectrical impedance measurements, which, when controlled for, may result in more accurate measurements. Despite this, questions remain in infants regarding the optimal size and placement of electrodes, the standardization of normal hydration, and the influence of body position on the distribution of water throughout the body. The technology requires further evaluation before being considered as a suitable tool to assess body composition in infancy.

Associations between maternal stress during pregnancy and offspring obesity risk later in life-A systematic literature review

Exposure to prenatal stress is linked to health consequences in the offspring. The objective of this systematic review was to synthesize and critically appraise primary human studies that have examined the association between prenatal exposure to psychosocial stress, or adverse life events, stress hormones, and later risk of developing obesity. We searched Medline, Embase, ScienceDirect, WorldCat, and OpenGrey up to January 2019 to identify relevant literature. We critically appraised the identified studies, assessed their quality, and summarized their findings. From a total of 5930 search results and references of studies that authors considered pertinent, we identified 15 relevant studies among which three were of high quality and the rest were medium-quality studies. We found direct association between exposure to stress in fetal life and different measures of obesity in the offspring in eight studies. The direct association was usually observed in studies that involved measurement of stress among mothers exposed to natural disasters. Due to lack of adequate and comparable data from the included studies, we did not conduct a meta-analysis. We concluded that there may be direct association between prenatal stress and later obesity, but further research with more comparable sources of stressors is recommended.

Body fat accrual trajectories for a sample of Asian-Canadian and Caucasian-Canadian children and youth: A longitudinal DXA-based study

BACKGROUND

Body fat accrual trajectories can be used to monitor trends in body fat mass and identify potential health risks. Currently, no body fat percent (BF%) centile distance and velocity curves exist for Canadian youth.

OBJECTIVES

To develop sex-specific and ethnic-specific BF% centile distance and velocity curves for White and Asian-Canadian youth.

METHODS

We utilized 4734 observations from 944 participants (female = 487; Asian = 532) to create sex-specific BF% velocity curves for age 10 to 18 years and sex-specific and ethnic-specific BF% percentile distance curves for ages 9 to 18 years for White and Asian children. BF% was derived from whole body DXA scans.

RESULTS

BF% centile distance curves for Asian and White girls were similar. BF% at most centiles plateaued around age 16 for Asian but not for White boys. Velocity curves for boys declined from age 11 to 13 years and then increased until age 18 years. For girls from 10 to 15 years, velocity curves converged towards the 50th centile then remained flat from 16 to 18 years.

CONCLUSIONS

BF% distance and velocity centiles can be used to identify when an individual veers from an average BF% accrual trajectory. In future, these curves may be used to investigate differences in fat mass and accrual across Canada.

External validation of the relative fat mass (RFM) index in adults from north-west Mexico using different reference methods

Background

Analysis of body composition is becoming increasingly important for the assessment, understanding and monitoring of multiple health issues. The body mass index (BMI) has been questioned as a tool to estimate whole-body fat percentage (FM%). Recently, a simple equation described as relative fat mass (RFM) was proposed by Woolcott & Bergman. This equation estimates FM% using two anthropometric measurements: height and waist circumference (WC). The authors state that due to its simplicity and better performance than BMI, RFM could be used in daily clinical practice as a tool for the evaluation of body composition. The aim of this study was to externally validate the equation of Woolcott & Bergman to estimate FM% among adults from north-west Mexico compared with Dual-energy X-ray absorptiometry (DXA) as an alternative to BMI and secondly, to make the same comparison using air displacement plethysmography (ADP), Bioelectrical Impedance Analysis (BIA) and a 4-compartment model (4C model).

Methods

Weight, height and WC were measured following standard procedures. The RFM index was calculated for each of the 61 participating subjects (29 females and 32 males, ages 20–37 years). The RFM was then regressed against each of the four body composition methods for estimating FM%.

Results

Compared with BMI, RFM was a better predictor of FM% determined by each of the body composition methods. In terms of precision the best equation was RFM regressed against DXA (y = 1.12 + 0.99 x; R² = 0.84 p<0.001). Accuracy (represented by the closeness to the zero-intercept) was 1.12 (95% CI: -2.44, to 4.68) and thus, not significantly different from zero. For the rest of the methods, precision in the prediction of FM% was improved compared to BMI, with significant increases in the R² and reduction of the root mean squared error (RMSE). However, the intercepts of each regression did not show accuracy since they were different from zero, for ADP: -9.95 (95%CI: -15.7 to -4.14), for BIA: -12.6 (95%CI: -17.5 to -7.74) and for the 4C model: -13.6 (95%CI: -18.6 to -8.60). Irrespectively, FM% measured by each of the body composition methods was higher for DXA than the other three methods (p<0.001).

Conclusions

This external validation proved that the performance of the RFM equation used in this study to estimate FM% was more consistent than BMI in this Mexican population, showing a stronger correlation with DXA than with the other body composition methods.

Monitoring children and adolescents with severe obesity: body mass index (BMI), BMI z-score or percentage above the International Obesity Task Force overweight cut-off?

AIM

Body mass index (BMI) metrics are widely used as a proxy for adiposity in children with severe obesity. The BMI expressed as the percentage of a cut-off percentile for overweight or obesity has been proposed as a better alternative than BMI z-scores when monitoring children and adolescents with severe obesity.

METHODS

Annual changes in BMI, BMI z-score and the percentage above the International Obesity Task Force overweight cut-off (%IOTF-25) were compared with dual-energy X-ray absorptiometry (DXA) derived body fat (%BF-DXA) in 59 children and adolescents with severe obesity.

RESULTS

The change in %BF-DXA was correlated with the change in %IOTF-25 (r = 0.68) and BMI (r = 0.70), and somewhat less with the BMI z-score (r = 0.57). Cohen's Kappa statistic to detect an increase or decrease in %BF-DXA was fair for %IOTF-25 (κ = 0.25; p = 0.04) and BMI (κ = 0.33; p = 0.01), but not for the BMI z-score (κ = 0.08; p = 0.5). The change in BMI was positively biased due to a natural increase with age.

CONCLUSION

Changes in the BMI metrics included in the study are associated differently with changes in %BF-DXA. The BMI z-score is widely used to monitor changes in adiposity in children and adolescents with severe obesity, but the %IOTF-25 might be a better alternative.

Relative Fat Mass as an estimator of whole-body fat percentage among children and adolescents: A cross-sectional study using NHANES

We evaluated the ability of the Relative Fat Mass (RFM) to estimate whole-body fat percentage among children and adolescents who participated in the National Health and Nutrition Examination Survey from 1999 through 2006 (n = 10,390). The RFM equation for adults (64 − (20 × height/waist circumference) + (12 × sex)) may be used for adolescents 15 to 19 years of age. For children and adolescents 8 to 14 years of age, we suggest a modified RFM equation, named as the RFMp (RFM pediatric): 74 − (22 × height/waist circumference) + (5 × sex). In both equations, sex equals 0 for boys and 1 for girls. RFMp was more accurate than BMI to estimate whole-body fat percentage (measured by dual energy X-ray absorptiometry, DXA) among girls (percentage of estimates that were <20% of measured body fat percentage, 88.2% vs. 85.7%; P = 0.027) and boys 8 to 14 years of age (83.4% vs. 71.0%; P < 0.001). RFM was more accurate than BMI among boys 15 to 19 years of age (82.3% vs. 73.9%; P < 0.001) but slightly less accurate among girls (89.0% vs. 92.6%; P = 0.002). Compared with BMI-for-age percentiles, RFMp had lower misclassification error of overweight or obesity (defined as a DXA-measured body fat percentage at the 85^th percentile or higher) among boys 8 to 14 years of age (6.5% vs. 7.9%; P = 0.018) but not girls (RFMp: 8.2%; BMI-for-age: 7.9%; P = 0.681). Misclassification error of overweight or obesity was similar for RFM and BMI-for-age percentiles among girls (RFM: 8.0%; BMI-for-age: 6.6%; P = 0.076) and boys 15 to 19 years of age (RFM: 6.9%; BMI-for-age: 7.8%; P = 0.11). RFMp for children and adolescents 8 to 14 years of age and RFM for adolescents 15 to 19 years of age were useful to estimate whole-body fat percentage and diagnose body fat-defined overweight or obesity.

The association between alexithymia and eating behavior in children and adolescents

OBJECTIVE

Alexithymia, or the difficulty identifying or describing one's own emotions, may be a risk factor for dysregulated eating and excess weight gain. However, the relationships between alexithymia and eating behaviors in community samples of non-clinical youth have not been well-characterized. We hypothesized that alexithymia would be positively associated with disordered and disinhibited eating in a community-based sample of boys and girls without an eating disorder.

METHOD

Two hundred children (8-17 years old) across the weight spectrum completed an interview to assess loss of control (LOC) eating and eating-related psychopathology, a laboratory test meal designed to induce disinhibited eating, and questionnaires to assess alexithymia, eating in the absence of hunger, and emotional eating. Linear and logistic regressions were conducted to examine the relationship between alexithymia and eating variables, with age, sex, race, and fat mass as covariates. Test meal analyses also adjusted for lean mass. Given the overlap between alexithymia and depression, all models were repeated with depressive symptoms as an additional covariate.

RESULTS

Alexithymia was associated with an increased likelihood of reporting LOC eating (p < .05). Moreover, alexithymia was positively associated with disordered eating attitudes, emotional eating, and eating in the absence of hunger (ps < .05). Greater alexithymia was associated with more carbohydrate and less fat intake at the test meal (ps < .05). After adjusting for depressive symptoms, alexithymia remained associated with eating in the absence of hunger and carbohydrate and fat intake (ps < .05).

DISCUSSION

In healthy children, alexithymia is associated with some facets of eating behavior and food intake. If supported prospectively, these preliminary findings suggest alexithymia may be a modifiable risk factor to reduce disordered eating and excess weight gain in youth.

Relationship of BMI z score to fat percent and fat mass in multiethnic prepubertal children

OBJECTIVE

The objective of the study is to examine the validity of body mass index z score (zBMI) as a measure of percent body fat in prepubertal children.

METHODS

One hundred eleven multiethnic, healthy, Tanner 1 children aged 6-12 years had fat percent and fat mass measured by the four-compartment method as part of the Paediatric Rosetta Body Composition Cohort. Multiple regression models were developed with fat percent as the dependent variable and zBMI, age, sex and ethnicity as independent variables.

RESULTS

Body mass index z score predicted fat percent, adjusted for age in both girls (P < 0.001, RMSE 5.67 and R² 0.54) and boys (P < 0.001, RMSE 4.71, R² 0.69). The average model percent error was 20.3% in girls and 21.6% in boys. zBMI² predicted fat mass when adjusted for age and zBMI in both girls (P < 0.001, RMSE 2.27 and R² 0.82) and boys (P < 0.001, RMSE 2.08 and R² 0.81). The average percent error was 7.2% in girls and 8.7% in boys. Age was associated with percentage body fat (P < 0.01), while ethnicity was not (P > 0.05).

CONCLUSIONS

Given the relatively large error in the models, zBMI are not a useful indicator of fat mass in healthy, Tanner 1 children. zBMI² scores are associated with significantly lower absolute percent errors in girls and boys.

Assessment of body composition changes during a combined intervention for the treatment of childhood obesity

OBJECTIVE

One of the main objectives in the treatment of childhood obesity is to reduce the percentage of body fat mass without negatively affecting fat-free mass (FFM) and, consequently, longitudinal growth. The aim of this study was to analyze the changes that take place in body compartments in a group of patients with obesity under combined treatment.

METHODS

This was a longitudinal study with 109 children with obesity 9.1 to 13.9 y of age included in a combined dietary-behavioral-physical activity intervention. Weight, height, skinfold thickness, and waist circumference were registered, and body mass index (BMI), fat mass index (FMI), FFM and waist-to-height ratio (WHR) were calculated over a period of 12 mo. The BMI z-score allowed us to establish two groups: obesity (n = 50) and severe obesity (n = 59). A nutritional improvement was considered when a decrease of BMI z-score of the initial value occurred after 12 mo of follow-up.

RESULTS

The improvement in nutritional status reached 61.5% (n = 67). In the obesity group with nutritional improvement (n = 32), FMI significantly decreased (P < 0.005) and there were no significant differences in weight, height z-score, FFM, and WHR throughout the combined intervention. In the severe obesity group with nutritional improvement (n = 35), there were no significant differences in weight, height z-score, FMI, FFM, and WHR throughout combined intervention.

CONCLUSIONS

Maintaining a constant weight in the mid- to long term to improve nutritional status would be adequate in children with infantile-juvenile obesity. However, maintaining a steady weight would not be sufficient for those patients diagnosed with severe obesity.

From Surveillance to Intervention: Overview and Baseline Findings for the Active City of Liverpool Active Schools and SportsLinx (A-CLASS) Project

This paper outlines the implementation of a programme of work that started with the development of a population-level children’s health, fitness and lifestyle study in 1996 (SportsLinx) leading to selected interventions one of which is described in detail: the Active City of Liverpool, Active Schools and SportsLinx (A-CLASS) Project. The A-CLASS Project aimed to quantify the effectiveness of structured and unstructured physical activity (PA) programmes on children’s PA, fitness, body composition, bone health, cardiac and vascular structures, fundamental movement skills, physical self-perception and self-esteem. The study was a four-arm parallel-group school-based cluster randomised controlled trial (clinical trials no. NCT02963805), and compared different exposure groups: a high intensity PA (HIPA) group, a fundamental movement skill (FMS) group, a PA signposting (PASS) group and a control group, in a two-schools-per-condition design. Baseline findings indicate that children’s fundamental movement skill competence levels are low-to-moderate, yet these skills are inversely associated with percentage body fat. Outcomes of this project will make an important contribution to the design and implementation of children’s PA promotion initiatives.

Body composition and prediction equations using skinfold thickness for body fat percentage in Southern Brazilian adolescents

OBJECTIVES

The purpose of this study was to: a) determine the nutritional status of Brazilian adolescents, and; b) present a skinfold thickness model (ST) to estimate body fat developed with Brazilian samples, using dual energy x-ray absorptiometry (DXA) as reference method.

METHODS

The main study group was composed of 374 adolescents, and further 42 adolescents for the validation group. Weight, height, waist circumference measurements, and body mass index (BMI) were collected, as well as nine ST-biceps (BI), triceps (TR), chest (CH), axillary (AX) subscapularis (SB), abdominal (AB), suprailiac (SI), medial thigh (TH), calf (CF), and fat percentage (%BF) obtained by DXA.

RESULTS

The prevalence of overweight in adolescents was 20.9%, and obesity 5.8%. Regression analysis through ordinary least square method (OLS) allowed obtainment of three equations with values of R2 = 0.935, 0.912 and 0.850, standard error estimated = 1.79, 1.78 and 1.87, and bias = 0.06, 0.20 and 0.05, respectively.

CONCLUSION

the innovation of this study lies in presenting new regression equations for predicting body fat in Southern Brazilian adolescents based on a representative and heterogeneous sample from DXA.

A simple equation to estimate body fat percentage in children with overweightness or obesity: a retrospective study

Background

Dual-energy X-ray absorptiometry (DXA) provides separate measurements of fat mass, fat-free mass and bone mass, and is a quick, accurate, and safe technique, yet one that is not readily available in routine clinical practice. Consequently, we aimed to develop statistical formulas to predict fat mass (%) and fat mass index (FMI) with simple parameters (age, sex, weight and height).

Methods

We conducted a retrospective observational cross-sectional study in 416 overweight or obese patients aged 4–18 years that involved assessing adiposity by DXA (fat mass percentage and FMI), body mass index (BMI), sex and age. We randomly divided the sample into two parts (construction and validation). In the construction sample, we developed formulas to predict fat mass and FMI using linear multiple regression models. The formulas were validated in the other sample, calculating the intraclass correlation coefficient via bootstrapping.

Results

The fat mass percentage formula had a coefficient of determination of 0.65. This value was 0.86 for FMI. In the validation, the constructed formulas had an intraclass correlation coefficient of 0.77 for fat mass percentage and 0.92 for FMI.

Conclusions

Our predictive formulas accurately predicted fat mass and FMI with simple parameters (BMI, sex and age) in children with overweight and obesity. The proposed methodology could be applied in other fields. Further studies are needed to externally validate these formulas.

Physical Activity and Changes in Adiposity in the Transition from Elementary to Middle School

OBJECTIVES

This study examined the longitudinal associations of objectively measured physical activity, sedentary behavior, and diet quality with two measures of adiposity and a measure of weight status.

METHODS

A total of 658 children from 21 elementary schools (45.1% boys; 40% white, 33% black, 9% Hispanic, and 18% other race/ethnicity) were assessed at least twice in fifth, sixth, and/or seventh grade. Fat mass index (FMI), percent body fat (PBF), and BMI were calculated from body weight, standing and seated heights, and bioelectrical impedance (BIA) measured each year.

RESULTS

At follow-up, both FMI and PBF decreased among boys and increased among girls, while BMI increased in both boys and girls. After controlling for race/ethnicity, parent education, and maturity offset at baseline, growth curve analyses showed that moderate-to-vigorous physical activity (MVPA) was significantly and negatively associated with FMI, PBF, and BMI for both boys and girls. After forming tertiles of fifth grade MVPA, least-square means for FMI, PBF, and BMI were examined by grade and gender. For both boys and girls, higher MVPA was associated with lower FMI, PBF, and BMI at all three grade levels. The relationships between sedentary behavior and diet quality and FMI, PBF, and BMI were not consistent for boys or girls.

CONCLUSIONS

As boys and girls transitioned from elementary to middle school, children who participated in higher levels of MVPA maintained more favorable levels of two indicators of adiposity and a measure of weight status. These findings support the need for interventions to help children meet current public health guidelines for physical activity.

Accuracy of different cutoff points of body mass index to identify overweight according to body fat values estimated by DEXA

OBJECTIVE

To evaluate the sensitivity and specificity of different cutoff points of body mass index for predicting overweight/obesity according to body fat values estimated by DEXA among Brazilian adolescents.

METHODS

Cross-sectional study including 229 male adolescents aged 10-15 years, in which body adiposity and anthropometric measures were assessed. Nutritional status was classified by BMI according to cutoff points described in scientific literature.

RESULTS

Moderate agreements were observed between body fat estimated by DEXA and cutoffs proposed by Cole et al. (K=0.61), Conde and Monteiro (K=0.65), Must et al. (K=0.61) and WHO (K=0.63). The BMI in continuous form showed good agreement with the Dexa (ICC=0.72). The highest sensitivity was observed for cutoff by Conde and Monteiro (0.74 [0.62, 0.84]) and the highest specificity by Cole et al. (0.98 [0.94, 0.99]). For the areas under the ROC curve of cutoff points analyzed, significant difference comparing the cutoff points by Cole et al. and Conde and Monteiro (0.0449 [0.00294, 0.0927]) was observed.

CONCLUSIONS

The cutoff proposed by Conde and Monteiro was more sensitive in identifying overweight and obesity when compared to the reference method, and the cutoff proposed by Cole et al. presented the highest specificity for such outcomes.

Utility of Body Mass Index in Identifying Excess Adiposity in Youth Across the Obesity Spectrum

OBJECTIVES

To determine the proportion of youth within a given body mass index (BMI) obesity category with excess adiposity using dual energy x-ray absorptiometry (DXA). Furthermore, to examine whether mean differences in cardiometabolic risk factors based upon various excess adiposity cutpoints were present.

STUDY DESIGN

DXA data from the National Health and Nutrition Examination Survey 1999-2006 (n = 10 465; 8-20 years of age) were used for this analysis. Obesity categories were defined using Centers for Disease Control and prevention definitions for age and sex. Excess adiposity was defined using cohort-specific cutpoints at 75th, 85th, and 90th percentiles of DXA body fat (%) by age and sex using quantile regression models. Additionally, we examined differences in cardiometabolic risk factors among youth (BMI percentile >85th) above and below various excess adiposity cutpoints.

RESULTS

Nearly all youth with class 3 obesity (100% male, 100% female; 97% male, 99% female; and 95% male, 96% female; using the 75th, 85th, and 90th DXA percentiles, respectively) and a high proportion of those with class 2 obesity (98% male, 99% female; 92% male, 91% female; and 76% male, 76% female) had excess adiposity. Significant discordance was observed between BMI categorization and DXA-derived excess adiposity among youth with class 1 obesity or overweight. Elevated cardiometabolic risk factors were present in youth with excess adiposity, regardless of the cutpoint used.

CONCLUSIONS

BMI correctly identifies excess adiposity in most youth with class 2 and 3 obesity but a relatively high degree of discordance was observed in youth with obesity and overweight. Cardiometabolic risk factors are increased in the presence of excess adiposity, regardless of the cutpoint used.

Evaluation of the predictive capacity of vertical segmental tetrapolar bioimpedance for excess weight detection in adolescents

OBJECTIVE

To analyze the predictive capacity of the vertical segmental tetrapolar bioimpedance apparatus in the detection of excess weight in adolescents, using tetrapolar bioelectrical impedance as a reference.

METHODS

This was a cross-sectional study conducted with 411 students aged between 10 and 14 years, of both genders, enrolled in public and private schools, selected by a simple and stratified random sampling process according to the gender, age, and proportion in each institution. The sample was evaluated by the anthropometric method and underwent a body composition analysis using vertical bipolar, horizontal tetrapolar, and vertical segmental tetrapolar assessment. The ROC curve was constructed based on calculations of sensitivity and specificity for each point of the different possible measurements of body fat. The statistical analysis used Student's t-test, Pearson's correlation coefficient, and McNemar's chi-squared test. Subsequently, the variables were interpreted using SPSS software, version 17.0.

RESULTS

Of the total sample, 53.7% were girls and 46.3%, boys. Of the total, 20% and 12.5% had overweight and obesity, respectively. The body segment measurement charts showed high values of sensitivity and specificity and high areas under the ROC curve, ranging from 0.83 to 0.95 for girls and 0.92 to 0.98 for boys, suggesting a slightly higher performance for the male gender. Body fat percentage was the most efficient criterion to detect overweight, while the trunk segmental fat was the least accurate indicator.

CONCLUSION

The apparatus demonstrated good performance to predict excess weight.