Search

Background: Pathways, a randomized trial, evaluated the effectiveness of a school-based obesity prevention program on body composition changes in American Indian children. Several body composition methods were compared in intervention and control schools for assessing body composition changes., Methods: Body composition methods, including skinfolds, bioelectric impedance analysis (BIA), body mass index (BMI), and using a combination of body composition methods were selected to assess 3-year changes in PBF in 705 children within 21 intervention schools and 663 children within 20 control schools. The study equation using skinfolds, BIA, and BMI was developed on a previous sample of American Indian children using deuterium oxide dilution as the criterion method., Results: Body fat changes among methods for the intervention sample ranged from 5.4% (BMI method) to 7.1% (combination of methods) and for the control sample, from 5.8% (BMI method) to 7.3% (combination of methods). The study equation estimates were significantly higher than the other methods and the BMI equation estimates were significantly lower than the other methods except by BIA. The BIA equation showed a significantly larger standard deviation of the difference over the 3-year intervention than each of the other methods indicating less reliability for detecting body composition changes., Conclusions: Within the Pathways large scale intervention trial with American Indian children, we found comparable yet significantly different mean PBF changes among methods. However, BIA was not as reliable as skinfolds and the combination of BIA, skinfolds, and body weight in assessing PBF changes.

Objective: This study was conducted to evaluate the association of total and central adiposity with serum cardiovascular disease (CVD) risk factors in lean and obese Portuguese children and adolescents., Research Methods and Procedures: A total of 87 girls (13.2 +/- 1.6 years old, 29.9 +/- 6.4% body fat [mean +/- SD]) and 72 boys (13.2 +/- 1.6 years old, 20.8 +/- 9.9% body fat) volunteered for the study. Whole-body composition and fat distribution, from DXA and anthropometry, and serum lipids, lipoproteins, and apolipoproteins were evaluated., Results: The sum of three trunk skinfolds (STS) was highly correlated with total trunk fat mass measured by DXA (p < 0.001). Body mass index, DXA-measured percentage of body fat, trunk fat mass, STS, and the waist-to-height ratio were generally found to be associated with triacylglycerol, the ratio of total cholesterol (TC) to high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), and apolipoprotein B levels, (significant age-adjusted r between 0.16 and 0.27, p < 0.05). Body mass index, STS, and the waist circumference were also associated with HDL-C (p < 0.05), whereas no body composition variable significantly correlated with TC or apolipoproteins A-I. The STS was significantly correlated with HDL-C (p < 0.01), TC/HDL-C (p < 0.05), and apolipoproteins A-I (p < 0.05) independently of whole-body fatness. Obese subjects (n = 73) had higher TC, LDL-C, TC/HDL-C, and apolipoprotein B than did non-obese subjects (n = 86), and significant associations between central adiposity and some lipid variables (triacylglycerol and HDL-C) were found in obese children and adolescents that were not present in leaner individuals., Discussion: DXA- and anthropometry-based whole-body and central fat measures are associated with serum CVD risk factors in Portuguese boys and girls. Obese children and adolescents have a poorer lipid profile than do their leaner counterparts. Trunk skinfolds, which are easy to obtain even in large samples, predict CVD risk factors to the same extent as DXA-based variables, in some cases, independently of total fatness.

The purpose of this study was to analyze the single and independent associations of whole body composition and fat distribution with cardiovascular disease (CVD) risk factors and fitness in middle-aged men. Sixty-two healthy Caucasian men (37.6 +/- 2.9 yr, 81.8 +/- 11.3 kg, 171.5 +/- 4.9 cm) participated in the study. Dual-energy x-ray absorptiometry (DXA) was used to assess total and regional body composition. The triceps, biceps, midthigh, calf, subscapular, chest, abdominal and suprailiac skinfolds, and the waist, hip and midthigh circumferences, and sagittal diameter were estimated. Cardiovascular fitness was estimated with a submaximal test. Bivariate and partial correlation analysis were used to study the association of total body percent fat (%fat), DXA trunk fat and trunk skinfolds (sum of subscapular, chest, abdominal, and suprailiac) and fitness with insulin, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), TC/HDL-C, low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), apolipoprotein AI (apo AI), apolipoprotein B (apo B), lipoprotein(a) [Lp(a)], and diastolic and systolic blood pressure. All anthropometric and DXA body composition variables were significantly correlated with TC/HDL-C (from .26 to .50, P < .05). Similar relationships were found for insulin, HDL-C, and systolic blood pressure (r from .26 to .47, P < .05). Cardiovascular fitness was significantly (P < .05) associated with insulin (r = -.36), HDL-C (r = .27), TC/HDL (r = -.27), and with systolic blood pressure (r = -.37). After controlling for trunk skinfolds, none of the anthropometric and DXA body composition variables were correlated with any of the CVD risk factors. Similarly, when controlling for trunk skinfolds, cardiovascular fitness was not related to any of the metabolic variables. After adjusting for %fat, DXA trunk fat, and cardiovascular fitness, trunk skinfolds remained significantly (P < .05) related to insulin (r = .35), HDL-C (r = -.40), TC/HDL-C (r = .43), and apo AI (r = -.39). In conclusion, this study suggests that subcutaneous truncal fat, as estimated by skinfolds, is an independent predictor of CVD risk factors, and that the association between cardiovascular fitness and these risk factors may be mediated by the levels of abdominal subcutaneous fat in Caucasian middle-aged men.

Objective: Obesity, as measured by body mass index, is highly prevalent in Native American children, yet there are no valid equations to estimate total body fatness for this population. This study was designed to develop equations to estimate percentage body fat from anthropometry and bioelectrical impedance as a critical part of Pathways, a multi-site study of primary prevention of obesity in Native American children., Design: Percentage fat was estimated from deuterium oxide dilution in 98 Native American children (Pima/Maricopa, Tohono O'odham and White Mountain Apache tribes) between 8 and 11 y of age. The mean fat content (38.4%+/-8. 1%) was calculated assuming the water content of the fat-free body was 76%. Initial independent variables were height, weight, waist circumference, six skinfolds and whole-body resistance and reactance from bioelectrical impedance (BIA)., Results: Using all-possible-subsets regressions with the Mallows C (p) criterion, and with age and sex included in each regression model, waist circumference, calf and biceps skinfolds contributed least to the multiple regression analysis. The combination of weight, two skinfolds (any two out of the four best: triceps, suprailiac, subscapular and abdomen) and bioelectrical impedance variables provided excellent predictability. Equations without BIA variables yielded r2 almost as high as those with BIA variables. The recommended equation predicts percentage fat with a root mean square error=3.2% fat and an adjusted r2=0.840., Conclusion: The combination of anthropometry and BIA variables can be used to estimate total body fat in field studies of Native American children. The derived equation yields considerably higher percentage fat values than other skinfold equations in children.

The whole-body bioelectrical impedance analysis (BIA) approach for estimating adiposity and body fat is based on empirical relations established by many investigators. Properly used, this noninvasive body-composition assessment approach can quickly, easily, and relatively inexpensively provide accurate and reliable estimates of fat-free mass (FFM) and total body water (TBW) in healthy populations. The estimated FFM or TBW values are used to calculate absolute and relative body fat amounts. When different investigators follow the same standard BIA procedures and use the same population and criterion method, similar prediction equations and relatively small prediction errors have been reported for measurement of FFM and TBW (SEE: 1.7-3.0 for FFM and 0.23-1.5 kg for TBW). The BIA approach is most appropriate for estimating adiposity of groups in epidemiologic and field studies but has limited accuracy for estimating body composition in individuals. When used as a simple index (stature2/ resistance), BIA is more sensitive and specific for grading average adiposity in groups than some other anthropometric indexes such as the body mass index. Prediction equations based on BIA have been validated and cross-validated in children, youths, adults, and the elderly, in primarily white populations and, to a limited extent, in Asian, black, and Native American populations.

Dehydroepiandrosterone (DHEA) has an antiobesity effect in rodents, and elevated endogenous levels of its sulfate ester (DHEAS) are associated with reductions in risk for cardiovascular disease (CVD) in men. To examine the association of body fat and fat distribution, established correlates of CVD and CVD risk factors, with circulating DHEAS levels in women, we measured trunk and limb skinfold thicknesses and circumferences, total and regional body fat from dual energy x-ray absorptiometry (DXA), and serum levels of DHEAS in 96 healthy Caucasian females aged 28-39 yr. Body mass index, percentage fat from DXA and the waist-to-hip ratio were not significantly correlated (r < or = 0.15, P > or = 0.156) with serum DHEAS levels, regardless of statistical control for age, smoking behavior, and fasting status. However, the ratio of trunk/total skinfold thicknesses (r = 0.23, P = 0.030) and the percentage of total fat located on the trunk from DXA (r = 0.32, P = 0.002) were positively correlated with DHEAS, whereas the ratio of leg/total skinfold thicknesses (r = -0.25, P = 0.015) and the percentage of total fat located on the legs from DXA (r = -0.25, P = 0.015) were inversely correlated with DHEAS after adjusting for age, smoking, and fasting status. With the exception of the trunk/total skinfold thickness ratio, the correlations of DXA- and skinfold-derived estimates of fat distribution remained significant (P < or = 0.033) even after further adjustment for percentage fat or body mass index. It is concluded that increased amounts of total fat located on the trunk and decreased amounts of total fat located on the legs are associated with increased serum DHEAS concentrations in normally menstruating females.

This study was designed to determine whether variability in bone mineral content (BMC) at the lumbar vertebrae (L2-4), radius shaft (RS), femoral neck, and distal radius can significantly contribute to the variability observed in body density (Db) among 89 females (age = 25.1 +/- 5.3 yr) of varying activity levels and menstrual status. Theoretical differences in Db were calculated at +/- 1 and +/- 2 standard deviations of BMC (SDBMC) for the population as well as for the subgroups: eumenorrheic inactive controls (C), recreational runners (RR), collegiate runners (CR), body builders (BB), swimmers (S), and amenorrheic runners (AR). Multiple regression to predict Db yielded significant coefficients (b) for BMC at L2-4 (b = 0.0190, P less than 0.001) and RS (b = 0.0425, P less than 0.01) when added separately to the sum of four skinfolds (subscapula, abdomen, thigh, calf). The differences in % BFHW at +/- 1 and +/- 2 SDBMC for the sample mean for RSBMC were +/- 1.0% and +/- 2.0%, respectively. Variability in L2-4 contributed differences of +/- 1.3% and +/- 2.6% at +/- 1 and +/- 2 SDBMC. The subgroup % BFHW differences (due to L2-4 and RS combined) ranged from an average overestimation of 1.3% for the AR to an average underestimation of 1.4% for the BB. Estimated mean errors for remaining groups were less than or equal to 0.5%. Individual differences ranged from a 3.3% underestimation (BB) to a 3.0% overestimation (AR).(ABSTRACT TRUNCATED AT 250 WORDS)