Search

Body composition estimates are widely used in clinical research and field studies as measures of energy-nutrient balance, functionality and health. Despite their broad relevance and multiple applications, important gaps remain in techniques available for accurately and precisely quantifying body composition in infants and children from birth through 5 years. Identifying these gaps and highlighting research needs in this age group were the topics of a National Institutes of Health workshop held in Bethesda, MD, USA, 30-31 May 2019. Experts reviewed available methods (multicompartment models, air-displacement plethysmography, dual-energy X-ray absorptiometry, weight-length and height indices, bioimpedance analysis, anthropometry-skinfold techniques, quantitative magnetic resonance, optical imaging, omics and D3-creatine dilution), their limitations in this age range and high priority research needs. A summary of their individual and collective workshop deliberations is provided in this report., (© 2020 World Obesity Federation.)

Objectives: To determine whether childhood body size, composition and blood pressure are associated with adult cardiac structure by estimating childhood "age of divergence.", Methods: 385 female and 312 male participants in the Fels Longitudinal Study had echocardiographic measurements of left ventricular mass, relative wall thickness, and interventricular septal thickness. Also available were anthropometric measurements of body mass index, waist circumference, percentage body fat, fat free mass, total body fat, and systolic and diastolic blood pressures, taken in both childhood and adulthood. The age of divergence is estimated as the lowest age at which childhood measurements are significantly different between patients with low and high measurements of adult cardiac structure., Results: Childhood body mass index is significantly associated with adult left ventricular mass (indexed by height) in men and women (ages of divergence: 7.5 years and 11.5 years, respectively), and with adult interventricular septal thickness in boys (age of divergence: 9 years). Childhood waist circumference indexed by height is associated with left ventricular mass (indexed by height) in boys (age of divergence: 8 years). Cardiac structure was in general not associated with childhood body composition and blood pressure., Conclusions: Though results are affected by adult body size, composition and blood pressure, some aspects of adult cardiac structure may have their genesis in childhood body size.

Purpose: Impact of lifestyle modification on obesity control during adolescence, a period of significant physical growth and development, is less quantitatively evaluated. Therefore, we investigated the impact of changes in reported energy intake and physical activity on anthropometrics and body composition in adolescents., Methods: Participants were obese adolescents aged 11-18 years. All of them have a body mass index (BMI) ≥ 95th percentile specific for age and gender according to the 2000 CDC Growth Charts. The intervention consists of supervised physical activity, structured nutrition education and dietary modification, and behavioral support in 6 months. Hundred and forty-five obese adolescents completed the study., Results: Compared to baseline, significant reductions in body weight (-1.4 kg, p < 0.001) and BMI (-0.1 kg/m(2), p < 0.001) were observed at 6 months. When compared to expected growth trajectories on the 2000 CDC Growth Charts, body weight and BMI were reduced by 3.6 kg and 1.5 kg/m(2), respectively, in boys and 5.6 kg and 1.9 kg/m(2) in girls. Age was inversely associated with changes in weight (β = -1.48 kg, p < 0.01) and BMI (β = -0.32 kg/m(2), p = 0.03). There was a dose-response relationship between reduction in energy intake and weight loss. A decrease of 100 kcal/day was significantly associated with reductions in body weight 0.30 kg, BMI 0.09 kg/m(2), and BMI Z score 0.01 (all p < 0.01). Physical activity was not significantly associated with changes in anthropometrics or body composition., Conclusions: Reduction in energy intake was a significant predictor of obesity reduction in these adolescents. A quantitative evaluation of adolescent weight loss programs should account for natural growth and development.

Objectives: To determine secular trends by birth decade in body mass index (BMI), waist circumference/height (W/Ht), percent body fat (PBF), and fat-free mass adjusted for height squared (FFM/Ht(2) ) in children and adolescents aged 8-18 years., Methods: Serial data were analyzed from 628 boys and 591 girls aged 8-18 years who participated in the Fels Longitudinal Study. Subjects were stratified by birth decade from 1960 to 1999. Means and standard deviations were computed for all measurements by birth decade, age, and sex. A repeated-measures analysis of variance was used data to ascertain secular trends separately for boys and girls., Results: Boys and girls born in the 1990s had significantly higher mean BMI, W/Ht, and PBF than did children born in previous decades. Mean FFM/Ht(2) was significantly smaller in boys born in the 1990s than boys of the same age born in earlier decades. No secular trend was noted in FFM/Ht(2) in girls by decade of birth., Conclusion: Our analysis of serial data collected over 4 decades confirms the secular trend in childhood BMI previously observed in successive cross-sectional studies. Our analysis discloses significant positive secular trends in W/Ht and PBF in both boys and girls and a significant negative secular trend in FFM/Ht(2) in boys over the last 4 decades of the 20th century. The secular changes presage increases in the prevalence of conditions associated with childhood and adolescent obesity-such as hypertension, glucose intolerance, and dyslipidemia-that may appear as early as the second decade of life., (Copyright © 2012 Wiley Periodicals, Inc.)

Background: Despite the recognition that central obesity plays a critical role in chronic disease, few large-scale imaging studies have documented human variation in abdominal adipose tissue patterning., Objective: We aimed to compare the associations between abdominal subcutaneous adipose tissue (ASAT) and visceral abdominal tissue (VAT), which were measured at different locations across the abdomen, and the presence of the metabolic syndrome (MS; National Cholesterol Education Program Adult Treatment Panel III definition) and individual cardiometabolic risk factors., Design: This study included 713 non-Hispanic whites aged 18-86 y, in whom VAT and ASAT were assessed by using multiple-image magnetic resonance imaging. The anatomical position of the magnetic resonance image containing the maximum VAT area for each subject was used as a measure of VAT patterning. Multivariate linear and logistic regression analyses were used to examine the relation of VAT, ASAT, and VAT patterning to cardiometabolic risk., Results: VAT mass was a stronger predictor of the MS than was ASAT mass, but ASAT mass (and other measures of subcutaneous adiposity) had signification interactions with VAT mass, whereby elevated ASAT reduced the probability of MS among men with high VAT (P = 0.0008). There was variation across image locations in the association of VAT area with the MS in men, and magnetic resonance images located 4-8 cm above L4-L5 provided the strongest correlations between VAT area and cardiometabolic risk factors. Subjects whose maximum VAT area was higher in the abdomen had higher LDL-cholesterol concentrations (R(2) = 0.07, P < 0.0001), independent of age and adiposity., Conclusion: Further studies are needed to confirm the effects of VAT patterning on cardiometabolic risk.

Objective: Our aim was to examine the degree to which changes in BMI percentile reflect changes in body fat and lean body mass during childhood and how age and gender affect these relationships., Methods: This analysis used serial data on 494 white boys and girls who were aged 8 to 18 years and participating in the Fels Longitudinal Study (total 2319 observations). Total body fat (TBF), total body fat-free mass (FFM), and percentage of body fat (%BF) were determined by hydrodensitometry, and then BMI was partitioned into its fat and fat-free components: fat mass index (FMI) and FFM index (FFMI). We calculated predicted changes (Delta) in FMI, FFMI, and %BF for each 10-unit increase in BMI percentile using mixed-effects models., Results: FFMI had a linear relationship with BMI percentile, whereas FMI and %BF tended to increase dramatically only at higher BMI percentiles. Gender and age had significant effects on the relationship between BMI percentile and FFMI, FMI, and %BF. Predicted Delta%BF for boys 13 to 18 years of age was negative, suggesting loss of relative fatness for each 10-unit increase in BMI percentile., Conclusions: In this longitudinal study of white children, FFMI consistently increased with BMI percentile, whereas FMI and %BF had more complicated relationships with BMI percentile depending on gender, age, and whether BMI percentile was high or low. Our results suggest that BMI percentile changes may not accurately reflect changes in adiposity in children over time, particularly among male adolescents and children of lower BMI.

The purpose of this study was to evaluate the influence of menarcheal age on changes in insulin, glucose, lipids, and blood pressure during adolescence and to assess whether body composition modifies this relationship. We examined 391 girls, a subset of Fels Longitudinal Study female participants (8-21 yr of age). Self-reported menarcheal age was classified based on the National Health and Nutrition Examination Survey III distribution, in which early menarche was at the 25th percentile or less (11.9 yr). Age at menarche was examined in relation to measures of body composition [e.g. fat-free mass (FFM) and percent body fat (PBF)], insulin resistance, blood pressure, and lipid profile. The effects of menarcheal age and body composition on cardiovascular disease risk factor changes were analyzed with serial data mixed models. Median menarcheal age was 12.7 yr (range, 9.8-17.0 yr), with 91 girls (23%) classified as early menarche. Girls with early menarche had more deleterious changes in insulin, glucose, blood pressure, FFM, and PBF levels than girls with average or late menarche. Menarcheal age adversely affected cardiovascular disease risk factor changes independent of age and changes in FFM or PBF. Girls with early menarche exhibited elevated blood pressure and glucose intolerance compared with later maturing girls, independent of body composition.

Background: Previous studies to develop and validate bioelectrical impedance analysis (BIA) equations to predict body composition were limited by small sample sizes, sex specificity, and reliance on reference methods that use a 2-component model., Objective: This study was designed to develop sex-specific BIA equations to predict total body water (TBW) and fat-free mass (FFM) with the use of a multicomponent model for children and adults., Design: Data from 5 centers were pooled to create a sample of 1474 whites and 355 blacks aged 12-94 y. TBW was measured by dilution, and FFM was estimated with a multicomponent model based on densitometry, isotope dilution, and dual-energy X-ray absorptiometry., Results: The final race-combined TBW prediction equations included stature(2)/resistance and body weight (R(2) = 0.84 and 0.79 and root mean square errors of 3.8 and 2.6 L for males and females, respectively; CV: 8%) and tended to underpredict TBW in black males (2.0 L) and females (1.4 L) and to overpredict TBW in white males (0.5 L) and females (0.3 L). The race-combined FFM prediction equations contained the same independent variables (R(2) = 0.90 and 0.83 and root mean square errors of 3.9 and 2.9 kg for males and females, respectively; CV: approximately 6%) and tended to underpredict FFM in black males (2.1 kg) and females (1.6 kg) and to overpredict FFM in white males (0.4 kg) and females (0.3 kg)., Conclusion: These equations have excellent precision and are recommended for use in epidemiologic studies to describe normal levels of body composition.

Body composition during puberty is a marker of metabolic changes that occur during this period of growth and maturation, and, thus, holds key information regarding current and future health. During puberty, the main components of body composition (total body fat, lean body mass, bone mineral content) all increase, but considerable sexual dimorphism exists. Methods for measuring body composition (e.g. densitometry and dual-energy X-ray absorptiometry) and degree of maturity will be discussed in this review. Components of body composition show age-to-age correlations (i.e. 'tracking'), especially from adolescence onwards. Furthermore, adipose tissue is endocrinologically active and is centrally involved in the interaction between adipocytokines, insulin and sex-steroid hormones, and thus influences cardiovascular and metabolic disease processes. In conclusion, pubertal body composition is important, not only for the assessment of contemporaneous nutritional status, but also for being linked directly to the possible onset of chronic disease later in life and is, therefore, useful for disease risk assessment and intervention early in life., (Copyright 2003 S. Karger AG, Basel)

The article presents a study which examined the relationship between childhood obesity and hypertension. The study is based on the Fels Longitudinal Study (FLS), which analyzed systolic blood pressure (SBP) and diastolic blood pressure (DBP) of Caucasian males and females. The role of lifestyle in determining body composition and hypertension is also considered.

Objective: We tested sex, race, and age differences in the patterning of visceral adipose tissue (VAT) and subcutaneous adipose tissue.Research Methods and Procedures: Contiguous 1-cm-thick magnetic resonance (MR) images of the abdomen were collected from 820 African-American and white adults. Repeated-measures ANOVA was used to examine the effects of image location, sex, race, and age (>or=50 vs. <50 years) on adipose tissue areas. Maximum VAT area was identified for each subject from the raw data.Results: Compared to women, men had greater total VAT volume (p < 0.0001), and their maximum VAT area occurred higher in the abdomen (p < 0.0001). Among white men, maximim VAT area most frequently occurred 5 to 10 cm above L4-L5, whereas in the other groups, maximim VAT area most frequently occurred 1 to 4 cm above L4-L5 (p < 0.0001). African-American men had greater total VAT volume than African-American women (p < 0.01), but this sex difference was only significant using single images cranial to L4-L5 + 2 cm. Age-related increases in VAT tended to be greatest 5 to 10 cm above L4-L5 in men and near L4-L5 in women.Discussion: A single MR image 5 to 10 cm above L4-L5 may allow more accurate conclusions than the L4-L5 image regarding group differences in visceral adiposity. [ABSTRACT FROM AUTHOR]

Background: A decline in the age at menarche was recently reported forUSgirls. Although it is possible that this recent drop stems from the concurrent increase in childhood obesity, few longitudinal studies of growth and development have been undertaken to specifically address the temporal relation between growth, adiposity, and the age at menarche. Objective: The objective was to simultaneously examine the effects of birth cohort (secular trend) and rate of maturation (age at menarche) on the timing and pattern of increases in body mass index (BMI) during adolescence in girls. Design:Weapplied mixed-effects polynomial models to serial BMI data, spanning from 6 y before menarche to 6 y after menarche, obtained from 211 girls enrolled in the Fels Longitudinal Study. We examined the effects of birth cohort (defined as girls born 1929- 1946, 1947-1964, and 1965-1983) and age at menarche (defined as ⩽11.9 y, 12.0 -13.1 y, and ⩾13.2 y) on the magnitude and velocity of BMI during adolescence. Results: BMI and BMI velocity in girls born after 1965 were significantly greater than those of girls of earlier birth cohorts, despite stability in the mean age at menarche. Although girls with early menarche tended to have significantly higher BMIs than did girls with average or later menarche, these differences did not emerge until after menarche. Conclusion: These data suggest that increases in relative weight are a consequence, rather than a determinant, of the age at menarche and that secular changes in BMI and in the mean age at menarche could be independent phenomena. [ABSTRACT FROM AUTHOR]