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Objective: The aim was to determine the most appropriate field techniques to measure %BF when both euhydrated and dehydrated. Design: A cross-sectional descriptive study was undertaken. Setting: South Africa. Subjects: 17 male apprentice jockeys (mean age 18.8 ± 1.7 years). Outcome measures: Agreement of %BF results determined using predictive equations based on skinfold thickness measurements and bioelectric impedance analysis (BIA) with that of the reference method, euhydrated deuterium dilution (eDD). Results: The mean %BF according to eDD was 9.5 ± 2.8%. The skinfold equations by Slaughter et al. (1988) for ages 8–18 years in either hydration state, Durnin and Womersley using either Siri or Brožek et al. for ages 17–19 years when dehydrated only, and the Van Loan et al. BIA equation when euhydrated only were the most acceptable methods. Conclusion: Regardless of hydration status, the skinfold equation by Slaughter et al. is recommended for jockey apprentices 18 years and younger. For those > 19 years, the hydration state must be confirmed prior to measurement. If euhydrated, the Van Loan et al. BIA equation is recommended and if dehydrated the Durnin and Womersley using either Siri or Brožek et al. is recommended.

Objective: The aim was to determine the most appropriate field techniques to measure %BF when both euhydrated and dehydrated. Design: A cross-sectional descriptive study was undertaken. Setting: South Africa. Subjects: 17 male apprentice jockeys (mean age 18.8 ± 1.7 years). Outcome measures: Agreement of %BF results determined using predictive equations based on skinfold thickness measurements and bioelectric impedance analysis (BIA) with that of the reference method, euhydrated deuterium dilution (eDD). Results: The mean %BF according to eDD was 9.5 ± 2.8%. The skinfold equations by Slaughter et al. (1988) for ages 8–18 years in either hydration state, Durnin and Womersley1 using either Siri2 or Brožek et al.3 for ages 17–19 years when dehydrated only, and the Van Loan et al.4 BIA equation when euhydrated only were the most acceptable methods. Conclusion: Regardless of hydration status, the skinfold equation by Slaughter et al.5 is recommended for jockey apprentices 18 years and younger. For those > 19 years, the hydration state must be confirmed prior to measurement. If euhydrated, the Van Loan et al.4 BIA equation is recommended and if dehydrated the Durnin and Womersley1 using either Siri2 or Brožek et al.3 is recommended. [ABSTRACT FROM AUTHOR]

We conducted the first validation of the deuterium dilution method as a nonlethal technique for estimating the body composition of a shorebird during fall staging as birds fatten in preparation for their migration. For this validation, we captured male (n = 12) and female (n = 8) American Woodcock (Scolopax minor) in the fall of 2018 and 2019 in southern New England, USA. We developed predictive models for estimating body composition of woodcock given each bird's body mass and deuterium space, a proxy for total body water space, estimated using the deuterium dilution method. Accuracy and precision of these predictive models were assessed by comparing the model predictions with directly measured body composition. The top models predicted whole-body lean and fat mass with a relative error of 1.37% and 11.26%, respectively. In comparison, conventionally used morphology-based condition indices were poor predictors of fat mass in fall-staging woodcock. We applied this method to accurately estimate body composition dynamics of woodcock during fall staging, a period of fattening in the annual cycle that is pertinent to subsequent migratory movements, phenology, survival, and habitat management for woodcock. This nonlethal technique also has broad applicability to other migratory birds that show substantial changes in body composition as they prepare for key life-history events such as migration. [ABSTRACT FROM AUTHOR]

The three-compartment (3-C) model of physique assessment (fat mass, fat-free mass, water) incorporates total body water (TBW) whereas the two-compartment model (2-C) assumes a TBW of 73.72%. Deuterium dilution (D2O) is the reference method for measuring TBW but is expensive and time consuming. Multifre-quency bioelectrical impedance spectroscopy (BIS SFB7) estimates TBW instantaneously and claims high precision. Our aim was to compare SFB7 with D2O for estimating TBW in resistance trained males (BMI >25kg/m²). We included TBWBIS estimates in a 3-C model and contrasted this and the 2-C model against the reference 3-C model using TBWD2O. TBW of 29 males (32.4 ± 8.5 years; 183.4 ± 7.2 cm; 92.5 ± 9.9 kg; 27.5 ± 2.6 kg/m²) was measured using SFB7 and D2O. Body density was measured by BODPOD, with body composition calculated using the Siri equation. TBWBIS values were consistent with TBWD2O (SEE = 2.65L; TE = 2.6L) as were %BF values from the 3-C model (BODPOD + TBWBIS) with the 3-C reference model (SEE = 2.20%; TE = 2.20%). For subjects with TBW more than 1% from the assumed 73.72% (n = 16), %BF from the 2-C model differed significantly from the reference 3-C model (Slope 0.6888; Intercept 5.093). The BIS SFB7 measured TBW accurately compared with D2O. The 2C model with an assumed TBW of 73.72% introduces error in the estimation of body composition. We recommend TBW should be measured, either via the traditional D2O method or when resources are limited, with BIS, so that body composition estimates are enhanced. The BIS can be accurately used in 3C equations to better predict TBW and BF% in resistance trained males compared with a 2C model. [ABSTRACT FROM AUTHOR]

Background: Measures that better describe "healthy" and sustainable recovery during nutritional treatment of children with moderate acute malnutrition (MAM) are needed.Objectives: We compared changes to body composition among children receiving 1 of 4 specialized nutritious food (SNFs) during treatment of MAM and by recovery and relapse outcomes.Methods: The study was nested within a prospective, cluster-randomized, community-based, cost-effectiveness trial assessing 4 SNFs to treat children aged 6-59 mo with MAM [midupper arm circumference (MUAC) ≥11.5 cm and <12.5 cm without bipedal edema] in Sierra Leone. Biweekly SNF rations (1 of 3 fortified-blended foods or a lipid-based nutrient supplement) were given until children recovered (MUAC ≥12.5 cm), or up to 7 rations (∼12 wk). Deuterium dilution was used to estimate fat-free mass (FFM) and fat mass (FM) at enrollment and after 4 wk of treatment to ensure similar treatment exposure among the participants. Another MUAC measurement was performed among recovered children 4 wk after program exit to determine whether recovery was sustained. ANOVA, paired t tests, and linear regression models were used to determine significant differences in changes from baseline to 4 wk.Results: Among 312 analyzed participants, mean baseline weight comprised ∼80% FFM; mean weight gained after 4 wk comprised ∼82% FFM. Changes in FM and FFM among 4 SNFs were similar. Children who recovered gained more weight (241%), FFM (179%), and weight-for-height z score (0.44 compared with 0) compared with those who did not recover; sustainers gained 150% more weight. FM gains were positive among recovered children and sustainers, as well as negative among those who did not recover or sustain recovery, but not significantly different.Conclusions: Four SNFs had similar effects on body composition in children after 4 wk of treatment for MAM, showing a healthy pattern of weight gain, the majority being FFM. Differential responses to treatment underscore a need for further research to provide targets for healthy, sustainable recovery. This trial was registered at clinicaltrials.gov as NCT03146897. [ABSTRACT FROM AUTHOR]

Body composition is associated with many noncommunicable diseases. The accuracy of many simple techniques used for the assessment of body composition is influenced by the fact that they do not take into account tissue hydration and this can be particularly problematic in paediatric populations. The aims of this study were: (1) to assess the agreement of two dual energy X-ray absorptiometry (DXA) systems for determining total and regional (arms, legs, trunk) fat, lean, and bone mass and (2) to compare lean soft tissue (LST) hydration correction methods in children. One hundred and twenty four healthy children aged between 6 and 16 years old underwent DXA scans using 2 GE healthcare Lunar systems (iDXA and Prodigy). Tissue hydration was either calculated by dividing total body water (TBW), by 4-component model derived fat free mass (HFFM TBW) or by using the age and sex specific coefficients of Lohman, 1986 (HFFM Lohman) and used to correct LST. Regression analysis was performed to develop cross-calibration equations between DXA systems and a paired samples t -test was conducted to assess the difference between LST hydration correction methods. iDXA resulted in significantly lower estimates of total and regional fat and lean mass, compared to Prodigy. HFFM TBW showed a much larger age/sex related variability than HFFM Lohman. A 2.0 % difference in LST was observed in the boys (34.5 kg vs 33.8 kg respectively, p < 0.05) and a 2.5% difference in the girls (28.2 kg vs 27.5 kg respectively, p < 0.05) when corrected using either HFFM TBW or HFFM Lohman. Care needs to be exercised when combining data from iDXA and Prodigy, as total and regional estimates of body composition can differ significantly. Furthermore, tissue hydration should be taken into account when assessing body composition as it can vary considerably within a healthy paediatric population even within specific age and/or sex groups. [ABSTRACT FROM AUTHOR]

Abstract Background Maternal recall is most commonly used to determine exclusive breastfeeding rates. A gold standard stable isotope method is available which can determine intake of breast milk versus water from sources other than breast milk and thus objectively determine exclusive breastfeeding. The objectives of this study were to determine exclusive breastfeeding rates by both maternal recall and the objective stable isotope method and discuss the limitations and usefulness of the two methods. Methods The study involved 100 mother-infant pairs in a peri-urban area in Durban, South Africa and study visits took place from July 2012 to September 2014. Maternal recall of exclusive breastfeeding was carried out using the World Health Organization’s 24 hour recall of infant feeding and this was compared to the objective measurement of exclusive breastfeeding using the stable isotope technique at three time points: six weeks, three and 5.5 months. The objective measurements were carried out using two different cut off values for exclusive breastfeeding. Kappa analysis was used to quantify the relationship between maternal recall and results from the stable isotope technique for each mother-infant pair. Results Over reporting of exclusive breastfeeding was common at the three different time points regardless of the cut off value used to assess exclusive breastfeeding by the stable isotope technique. Kappa analysis also revealed only slight or fair agreement (K

Background: Reliable and accurate estimates of body composition are essential when studying the various health correlates of disease. Bioelectrical impedance analysis (BIA) is an affordable and feasible body composition assessment technique for clinical and field settings. Total body water (TBW) and hence fat-free mass is estimated by predictive regression algorithms using anthropometric measurements plus the resistance index. Aim: The study aimed to develop a BIA prediction equation for TBW in children in Myanmar using the deuterium dilution technique as the reference method. Methods: The study design was cross-sectional in a school setting with convenience sampling of participants. One hundred and two healthy children (57 boys and 45 girls) with aged 4 and 8 years participated; randomly divided into the prediction group (29 boys and 22 girls) and cross-validation group (28 boys and 23 girls). Whole-body impedance, anthropometric and TBW (by D 2 O dilution) measurements. The prediction equation was cross-validated using a split-group design and compared to published equations for contemporaneous populations. Results: TBW could be predicted by the following equation. TBW = 0.4597 * Weight (kg) + 0.1564 * Impedance index + 0.6075 ( R 2  = 0.891, P  < 0.0001) with a correlation coefficient of 0.942 and limits of agreement of 0.98 kg TBW on cross-validation. Conclusions: This equation can be used to predict body composition in young (aged 4-8 years) children in Myanmar but because the age range of the participants in the present study was relatively narrow, more research in different age groups is required to establish its broader applicability., Competing Interests: Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Author Ward provides consultancy services to ImpediMed Ltd, manufacturer of impedance devices. ImpediMed had no input into the design, conduct or reporting of this study. All other authors have no conflicts to declare.

ABSTRACT We conducted the first validation of the deuterium dilution method as a nonlethal technique for estimating body composition of a sea duck. We captured male (n = 11) and female (n = 8) American common eiders (Somateria mollissima dresseri) during winters of 2011–2012 and 2012–2013 in southern New England, USA, and compared their directly measured body composition with that estimated using deuterium‐dilution. The best‐supported linear regression models predicted wet lean and fat mass with, on average, 2.0% and 20.2% relative errors, respectively. The deuterium dilution method provides field biologists and managers with a nonlethal method for accurately estimating body composition of common eider during winter. The method is broadly applicable to other migratory birds and can be used to evaluate the effects of ecological and anthropogenic drivers on body composition dynamics. © 2016 The Wildlife Society.

ABSTRACT The nearshore and offshore waters of southern New England provide some of the most important wintering habitat for sea ducks in North America. Understanding changes in sea duck body composition during winter could provide insights into current habitat quality and potential effects of anthropogenic disturbances on the body condition of sea ducks. We used the deuterium dilution method, a nonlethal approach, to investigate intraseasonal variation and differences between genders in body composition of 86 adult common eiders (Somateria mollissima) during winter (2011 and 2012) in southern New England. Both male (n = 39) and female (n = 47) eiders increased fat mass by 75% in late winter compared with early winter. Wet lean mass of males remained constant throughout the winter, while that of females decreased by 10%. These seasonal increases in fat stores of eider suggest that birds were able to secure adequate resources to improve their body condition over winter. Our estimates of body composition of eider during winter in southern New England can be used as a baseline when conducting future research to evaluate effects of anthropogenic disturbance and disease. © 2016 The Wildlife Society.

There is no data on the prevalence of overweight and obesity in young Syrian boys. Therefore, the present study aimed to provide baseline and reference data on the prevalence of overweight and obesity among young Syrian boys using skin-fold thickness measurements and deuterium dilution (DD) as a reference method. The sample of 2470 healthy Syrian 18- to 19-year-old boys were enrolled in this study. SFTs were measured at the biceps (B), triceps (T), subscapular (SI) and suprailiac locations (SS) were done and validated using the DD technique as a reference method. Receiver operating characteristics (ROC) curve was drawn to determine appropriate cut-off points of the Σ2 limb SFT (T+B), Σ2 trunk SFT (SI+SS), Σ4 SFT (T+B+SI+SS) and Log Σ4 SFT for defining overweight and obesity. The overall prevalence of overweight and obesity in young Syrian boys, based on biceps SFT, triceps SFT, subscapular SFT, suprailiac SFT, Σ2 limb SFT, Σ2 trunk SFT, Σ4 SFT, logarithm Σ4 SFT, and DDT were 35.3%, 32%, 31.6%, 14.8%, 32.9%, 26.6%, 28.1%, 24.1%, 46.5%, respectively. Strongly positive correlation was found between SFT and total body fat in adolescents. For diagnosing overweight on the basis of Σ2 limb SFT, Σ2 trunk SFT, Σ4 SFT and logarithm Σ4 SFT, we propose the following cut-off points: 17.25 mm, 23.50 mm, 39.25 mm and 1.60, respectively. To predict obesity, Σ2 limb SFT, Σ2 trunk SFT, Σ4 SFT and logarithm Σ4 SFT threshold were increased to 23.25 mm, 32.50 mm, 55.25 and 1.75, respectively. Basing on SFT clearly leads to underestimates of the prevalence of weight problems among young boys. SFT measurement screen missed 11.2 to 31.7% of overall overweight and obesity cases.

Summary Background/objectives Accuracy of impedance analysis depends on population-specific prediction equations. The aim of this study was to propose new prediction equations to estimate body composition using impedance analysis for healthy Tunisian children and validate them using the deuterium oxide dilution (D 2 O) technique. Subjects/methods Body composition was estimated by the Tanita impedance analyzer. The validity of this system was investigated in 134 school children aged between 8 and 11 years. The validity of other published equations was also tested in our sample. Total body water (TBW) and Fat-Free Mass (FFM) were determined using the D 2 O technique. Participants were divided equally into development (n = 67) and validation groups (n = 67) to develop prediction equation using linear regression models. Results The comparison between body composition obtained by Tanita system and by D 2 O technique illustrated a significant difference (p < 0.01). Compared to D 2 O technique, Tanita impedance analysis underestimates fat mass and overestimates FFM and TBW. The prediction equations for TBW and FFM were developed with sex, age, weight and resistance index as possible predictor variables. The selected equations presented the highest adjusted coefficient of determination (R2), the lowest standard error of the estimate (SEE) value and the lowest p-values. The pure error was 1.263 for the TBW equation and 1.646 for the FFM. The Bland Altman plot illustrated the good level of concordance between the TBW and FFM predicted by the new equations and measured by isotope dilution. Conclusions Our study provides valid prediction equations for estimation of TBW, FFM from impedance analysis measures for Tunisian children. These equations are applicable to children aged between 8 and 11 years. [ABSTRACT FROM AUTHOR]

Background: Although the impact of gestational weight gain (GWG) on birth weight in twin pregnancies has been demonstrated, the specific components of GWG have not been delineated for twin gestations. Fetal body composition has been shown to be modifiable in singleton gestations based on nutritional intervention strategies and may prove to have similar modifications in twin gestations. Objective: We aimed to determine the relation of maternal body composition changes to birth weight, birth length, and neonatal fat mass (FM) in dichorionic-diamniotic twin pregnancies. Design: This is a prospective study of 20 women with twin gestations. Comparisons were made between body composition variables during each trimester and for the entire pregnancy and compared with the outcomes of birth weight, neonatal fat percentage, and birth length. Results: GWG within or above compared with below the IOM recommendations was associated with higher birth weights (P = 0.03, P = 0.04, respectively), but also with higher postpartum weight retention (P = 0.001). Total maternal protein gain over the pregnancy was positively associated with birth weight (P = 0.03). Changes in maternal fat-free mass (FFM), total body water (TBW), and FM from the first to the third trimester were not associated with either birth weight or neonatal FM percentage. However, maternal FM change from the second to the third trimester was significantly correlated to neonatal FM percentage (P = 0.02). Third trimester GWG and total protein gain were positively correlated with neonatal birth length (P = 0.02 and 0.03, respectively). Maternal FFM over all 3 trimesters showed a positive relation with neonatal birth length (P = 0.01). Conclusions: Significant increases in maternal protein are associated with greater birth weight and neonatal birth length. Protein accretion, in contrast to TBW and FM gains, may be the most critical component of maternal GWG in dichorionic twin gestations. [ABSTRACT FROM AUTHOR]

Vector-borne diseases have increased pesticide use in urban areas (UA) and agricultural areas (AA) in Mexico. Breast milk can be contaminated by pesticide exposure. The objective of the study was to measure breast milk intake by deuterium oxide dilution as well as organochlorine and pyrethroid transfer from mother to infant in AA and UA of Sonora, Mexico. Human milk intake was determined by the ’dose-to-mother’ technique using deuterium oxide (D 2 O) dilution. Mothers’ body composition was also assessed by this technique and the intercept method. Pyrethroids (deltamethrin, cypermethrin and cyhalothrin) and organochlorine pesticide residues ( p,p’- DDT, p,p’ - DDE, p,p’- DDD) in breast milk samples were measured by gas chromatography. Sixty-two lactating women and their infants participated in the study, 32 lived in the UA and 30 lived in the AA. Breast milk intake was approximately 100 mL higher in the AA than in the UA 799 ± 193 and 707 ± 201 mL/day, respectively (p < 0.05). The concentrations of p,p’ - DDT and cypermethrin levels in breast milk were higher in the UA than in the AA (p < 0.05 and p = 0.001, respectively). None of the pyrethroids and organochlorine pesticides studied surpassed the Acceptable Daily Intake (ADI) in milk for humans according to EPA and FAO/WHO. In conclusion, breast milk intake was higher in the AA compared to the UA. The p,p’- DDT and cypermethrin levels in breast milk were higher in the UA compared to the AA. Since pesticide levels in human milk did not exceed the ADI, breastfeeding is still a safe practice and should be encouraged. [ABSTRACT FROM AUTHOR]

Childhood malnutrition is highly prevalent and associated with high mortality risk. In observational and interventional studies among malnourished children, body composition is increasingly recognised as a key outcome. The deuterium dilution technique has generated high-quality data on body composition in studies of infants and young children in several settings, but its feasibility and accuracy in children suffering from moderate acute malnutrition requires further study. Prior to a large nutritional intervention trial among children with moderate acute malnutrition, we conducted pilot work to develop and adapt the deuterium dilution technique. We refined procedures for administration of isotope doses and collection of saliva. Furthermore, we established that equilibration time in local context is 3 h. These findings and the resulting standard operating procedures are important to improve data quality when using the deuterium dilution technique in malnutrition studies in field conditions, and may encourage a wider use of isotope techniques. [ABSTRACT FROM PUBLISHER]

Steller sea lion ( Eumetopias jubatus) young-of-the-year ( YOY) are nutritionally dependent upon their dam through the majority of their first year. Several indices of body condition were measured in YOY 1.5-9 mo of age captured in Southeast Alaska ( n = 122), the Gulf of Alaska ( n = 182), and the Aleutian Islands ( n = 38) to test the hypothesis that nutritional stress impacted the ability of adult female Steller sea lions to adequately nourish their late gestation YOY in the central Aleutian Islands in the early 2000s. Body mass (kg) and percent total body lipid content (% TBL) increased with age in all three regions of Alaska that were sampled ( P < 0.05). Young-of-the-year 7-9 mo of age were leaner in Southeast Alaska (27.6% ± 1.0%) and Gulf of Alaska (29.5% ± 0.8%) than in the Aleutian Islands (35.7% ± 1.2%, P < 0.001). Condition indices calculated from morphometric measures did not strongly predict the % TBL measured by isotope dilution. The trend for Aleutian Island YOY to have larger body mass and larger body fat reserves are counter to what would be expected if dams were unable to adequately provision their late lactation YOY due to inadequate food availability in the central Aleutian Islands. [ABSTRACT FROM AUTHOR]

ABSTRACT The nearshore and offshore waters of southern New England provide some of the most important wintering habitat for sea ducks in North America. Understanding changes in sea duck body composition during winter could provide insights into current habitat quality and potential effects of anthropogenic disturbances on the body condition of sea ducks. We used the deuterium dilution method, a nonlethal approach, to investigate intraseasonal variation and differences between genders in body composition of 86 adult common eiders ( Somateria mollissima) during winter (2011 and 2012) in southern New England. Both male ( n = 39) and female ( n = 47) eiders increased fat mass by 75% in late winter compared with early winter. Wet lean mass of males remained constant throughout the winter, while that of females decreased by 10%. These seasonal increases in fat stores of eider suggest that birds were able to secure adequate resources to improve their body condition over winter. Our estimates of body composition of eider during winter in southern New England can be used as a baseline when conducting future research to evaluate effects of anthropogenic disturbance and disease. © 2016 The Wildlife Society. [ABSTRACT FROM AUTHOR]

ABSTRACT We conducted the first validation of the deuterium dilution method as a nonlethal technique for estimating body composition of a sea duck. We captured male ( n = 11) and female ( n = 8) American common eiders ( Somateria mollissima dresseri) during winters of 2011-2012 and 2012-2013 in southern New England, USA, and compared their directly measured body composition with that estimated using deuterium-dilution. The best-supported linear regression models predicted wet lean and fat mass with, on average, 2.0% and 20.2% relative errors, respectively. The deuterium dilution method provides field biologists and managers with a nonlethal method for accurately estimating body composition of common eider during winter. The method is broadly applicable to other migratory birds and can be used to evaluate the effects of ecological and anthropogenic drivers on body composition dynamics. © 2016 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Background: Body composition assessment in the first 2 y of life provides important insights into child nutrition and health. The application and interpretation of body composition data in infants and young children have been challenged by a lack of global reference data., Objectives: We aimed to develop body composition reference charts of infants aged 0-6 mo based on air displacement plethysmography (ADP) and those aged 3-24 mo based on total body water (TBW) by deuterium dilution (DD)., Methods: Body composition was assessed by ADP in infants aged 0-6 mo from Australia, India, and South Africa. TBW using DD was assessed for infants aged 3-24 mo from Brazil, Pakistan, South Africa, and Sri Lanka. Reference charts and centiles were constructed for body composition using the lambda-mu-sigma method., Results: Sex-specific reference charts were produced for FM index (FMI), FFM index (FFMI), and percent FM (%FM) for infants aged 0-6 mo (n = 470 infants; 1899 observations) and 3-24 mo (n = 1026 infants; 3690 observations). When compared with other available references, there were observable differences but similar patterns in the trajectories of FMI, FFMI, and %FM., Conclusions: These reference charts will strengthen the interpretation and understanding of body composition in infants across the first 24 mo of life., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: the deuterium dilution technique is a reference method for measuring body composition in children. However, to our knowledge, there is no report on how some of the procedures used affect the measurement of total body water (TBW) and other estimates. Objective: to analyze whether considering fluid intakeand urine excretion during the test affects the final TBW, fat mass and fat free mass results. Results and discussion: ingestion of fluids (100 mL rinse water + orange juice 150 mL) and excretion (urine) were measured in 139 schoolchildren (65 girls) during the determination of TBW. We found significant differences in body composition (p < 0.001), TBW (100-200 mL), FFM and FM (100-300 g) when corrected by volume of fluids ingested and excreted. However, these differences were not considered clinically relevant. [ABSTRACT FROM AUTHOR]

Background: Equations based on single-frequency bioelectrical impedance analysis at 50 kHz for determination of total body water content (TBW) have been previously validated in healthy non-sedated beagle dogs. We investigated whether these equations are predictive of TBW in various canine breeds by comparing the results of these equations with TBW values evaluated directly by deuterium oxide (D2O) dilution. Methods: Total body water content of 13 healthy adult pet dogs of various breeds was determined directly using D2O dilution and indirectly using previous equations based on values obtained with a portable bioelectric impedance device. Paired Student's t-tests were used to compare TBW obtained by single-frequency bioelectrical impedance analysis and D2O dilution. A p-value of <0.05 was considered statistically significant for all analyses. Results: Significant differences were observed between TBW determined by the reference method and the values obtained with both predictive equations. Conclusions: The proposed equations including single-frequency bioelectrical impedance analysis parameters validated at 50 kHz in healthy adult beagles need to be modified including morphological parameters such as body size and shape in a first approach. As in humans, morphological-specific equations have to be developed and validated. [ABSTRACT FROM AUTHOR]

Aim Multi-frequency bioelectrical impedance analysis ( MF- BIA) may provide a quick, cost-efficient method of total body water ( TBW) assessment. We compared TBW estimates from the Biospace In Body 520, 720, and S10 MF- BIA devices to TBW estimates from isotopic deuterium dilution ( D2 O). Methods TBW was measured in 25 men and 25 women, 18-49 years, 73.6 ± 15.4 kg on each of the three devices and from D2 O analysis. Results All MF- BIA devices significantly overestimated TBW compared to D2 O TBW for men (4.7-5.4 kg, 10.8-12.4%; P < 0.01) and women (3.7-4.3 kg, 12.3-14.3%; P < 0.01). Regression analyses in men revealed R2 (0.86-0.90) and SEE (1.7-2.0 kg), and in women revealed R2 (0.82-0.86) and SEE (1.5-1.6 kg). Bland and Altman analyses revealed similar limits of agreement for men (3.5-3.9 kg) and women (3.4-3.7 kg). Conclusions The Biospace InBody devices significantly overestimate TBW in men and women. The consistent bias for men and the increasing bias with increasing TBW for women may indicate that these devices are suitable for group TBW estimates in men only. [ABSTRACT FROM AUTHOR]

Background: Direct anthropometric measurements to assess body composition have limited precision and/or specificity., Objectives: The study aimed to develop a prediction equation based on anthropometric measurements for estimating total body water (TBW) in a healthy population., Methods: TBW was assessed using the deuterium dilution method in 398 Moroccan participants (235 women and 163 men) aged 11.6-88 y, then compared to the estimations made by previously published anthropometric equations. By sex, participants were randomly assigned into development (n = 199) and validation subgroups (n = 199). A new anthropometric equation was developed in the development subgroup from data obtained on body volume (BV), weight, and sex, where the BV was calculated from participants' height. Then the equation was validated in the validation subgroup using the Bland and Altman procedure, bias, and pure error. External validation was performed using a sample from Tunisia (n = 220, 51.8% female, 18-65 y)., Results: Bias in predicting TBW showed unacceptable value for all previously published equations as it was significantly overestimated. The following new equation using anthropometric measurements [TBW (kg) = -5.249 + 107.502 BV (L) + 0.289 weight (kg) + 2.015 sex (male: 1, female: 0); (R 2 = 0.91, RMSE = 1.885 kg)] was developed, and its internal validation was confirmed. The generated bias and pure error values were 0.047 kg (95% CI: -0.235, 0.330) and 2.02 kg (95% CI: 1.73, 2.31), respectively. The external validation of the new TBW prediction equation on a Tunisian sample showed a bias and pure error values of 0.07 kg (95% CI: -0.289, 0.429) and 2.36 kg, respectively., Conclusions: The results indicate that the new anthropometric-based prediction equation provides a good estimation of TBW and other body composition compartments. It could be recommended as an alternative method to assess body composition for epidemiological and clinical studies., (Copyright © 2023 American Society for Nutrition. Published by Elsevier Inc. All rights reserved.)

Background: BIA represents an important tool in body composition (BC) assessment, especially in low-income settings in which simple and affordable options are preferred. There is a particular need to measure BC in stunted children, in which cases population-specific BIA estimating equations are lacking., Objectives: We calibrated an equation to estimate body composition from BIA using deuterium dilution ( 2 H) as the criterion method in stunted children., Methods: We measured BC with 2 H and performed BIA in stunted Ugandan children (n = 50). Multiple linear regression models were constructed to predict 2 H-derived FFM from BIA-derived whole-body impedance and other relevant predictors. Model performance was expressed as adjusted R 2 and RMSE. Prediction errors were also calculated., Results: Participants were aged 16-59 mo, of whom 46% were girls, and their median (IQR) height-for-age z-score (HAZ) was -2.58 (-2.92 to -2.37) according to the WHO growth standards. Impedance index (height 2 /impedance measured at 50 kHz) alone explained 89.2% variation in FFM and had an RMSE of 583 g (precision error 6.5%). The final model contained age, sex, impedance index, and height-for-age z-score as predictors and explained 94.5% variation in FFM with an RMSE of 402 g (precision error 4.5%)., Conclusions: We present a BIA calibration equation for a group of stunted children with a relatively low prediction error. This may help evaluate the efficacy of nutritional supplementation in large-scale trials in the same population. J Nutr 20XX;xxx:xx., (Copyright © 2023 American Society for Nutrition. Published by Elsevier Inc. All rights reserved.)

Background In developing countries where access to water and food is not guaranteed, women may have to travel long distances or engage in intense physical activities to gather food. This may compromise their water requirements and overall nutritional status. The aim of the study was to determine water turnover, physical activity and body composition among women in Kenya and to describe the differences between rural and urban Kenyan women. Methods Thirty women from Narok County who were not pregnant at the time of the study were recruited. Body mass index (BMI) was calculated by dividing weight in kilograms by height in meters squared. Deuterium dilution was used to determine total body water (TBW) and water turnover was measured from deuterium elimination. Fat-free mass (FFM) was calculated by assuming a constant hydration fraction of 73.2%. Accelerometers (Actigraph GT3X) were used to assess physical activity and expressed as Vector magnitude counts per day (VM/day). Simple and multiple linear regressions were used to define the determinants of water turnover. Results Mean BMI was 23.4 ± 4.1 and 21.5 ± 3.8 among rural and urban women respectively. The prevalence of overweight (BMI > 25 kg/m²) was 24.1% and of underweight (BMI < 18.4 kg/m²) was 25%. The mean total body water (TBW) was 29.3 ± 4.2 liters (L) and water turnover was 3.2 ± 0.8 liters per day (L/day). Water loss was positively associated with BMI (R² = .45, p < 0.001, n = 28) and Fat mass index (FMI) (R² = .41, p < 0.001, n = 28). Water loss was also positively associated with physical activity (PA) (R² = .25, p < 0.05, n = 22). Multiple regression analysis showed that physical activity in addition to BMI in the model explained an additional 15% of the variation in water turnover (r² = 0.53, p < 0.05; Δr² = 0.15, p < 0.05, n = 22) compared to BMI alone (r² = 0.38, p < 0.005 n = 22). Conclusion BMI together with physical activity were the strongest predictors of water loss. [ABSTRACT FROM AUTHOR]

Abstract: Aim of the study was to assess the accuracy and precision of a BIS device and the relative contribution of BIS beyond the anthropometric parameters. The output of the Impedimed device (SFB7) and the relative contribution of height, weight, age, sex and resistance values at zero and infinite frequency (R zero and R inf respectively) to the prediction of total body water (TBWd, deuterium space), of extracellular fluid (ECFbr, sodium bromide space) and of fat mass (FMDXA) were assessed in 116 subjects (32 healthy subjects and 84 patients with disorders of body composition). Using a repeated randomization procedure, new equations for TBW, ECF and FM were derived. The SFB7 gave measures of determination similar to those obtained with equations that included only anthropometric data. The SFB7, but not the newly derived regression equations, underestimated TBW and ECF by 3.82±3.37 (mean±SD) and by 0.93±2.62l and overestimated FM by 6.55±3.86kg. Nine of 16 patients with ECF overload as detected by ECFbr were also detected by BIS. BIS measurements contribute marginally but not significantly beyond anthropometric data to the prediction of TBW, ECF and FM, either in healthy subjects or in patients with disturbed body composition. [Copyright &y& Elsevier]

Seals must manage their energy reserves carefully while they fast on land to ensure that they go to sea with sufficient fuel to sustain them until they find food. Glucocorticoids (GCs) have been implicated in the control of fuel metabolism and termination of fasting in pinnipeds. Here we tested the hypothesis that dexamethasone, an artificial GC, increases fat and protein catabolism, and induces departure from the breeding colony in wild, fasting grey seal pups. A single intramuscular dose of dexamethasone completely suppressed Cortisol production for 24-72 h, demonstrating activation of GC receptors. In experiment 1, we compared the effects of a single dose of dexamethasone or saline administered 10 days after weaning on fasting mass and body composition changes, Cortisol, blood urea nitrogen (BUN) and glucose levels, and timing of departure from the colony. In experiment 2, we investigated the effects of dexamethasone on short-term (5 days) changes in mass loss, body composition and BUN levels. In experiment 1, dexamethasone induced a short-lived increase in mass loss, but there was no difference in timing of departure between dexamethasone- and saline-treated pups (N=10). In experiment 2, dexamethasone increased protein and water loss and prevented a decrease in BUN levels (N=11). Our data suggest changes in Cortisol contribute to regulation of protein catabolism in fasting seal pups, irrespective of the sex of the animal, but do not terminate fasting. By affecting the rate of protein depletion, lasting changes in Cortisol levels could influence the amount of time seal pups have to find food, and thus may have important consequences for their survival. [ABSTRACT FROM AUTHOR]

Anthropometrics and body mass index are only proxies in the evaluation of adiposity in the pediatric population. Air displacement plethysmography technology was not available for children aged 6 months to 9 years until recently. Our study was designed to test the precision of air displacement plethysmography (ADP) in measuring body fat mass in children at ages 3 to 5 years compared with a criterion method, deuterium oxide dilution (D2O), which estimates total body water and a commonly used methodology, dual-energy x-ray absorptiometry (DXA). A prospective, cross-sectional cohort of 66 healthy children (35 girls) was recruited in the central Arkansas region between 2007 and 2009. Weight and height were obtained using standardized procedures. Fat mass (%) was measured using ADP, DXA, and D2O. Concordance correlation coefficient and Bland-Altman plots were used to investigate the precision of the ADP techniques against D2O and DXA in children at ages 3 to 5 years. ADP concordance correlation coefficient for fat mass was weak (0.179) when compared with D2O. Bland-Altman plots revealed a low accuracy and large scatter of ADP fat mass (%) results (mean=−2.5, 95% CI −20.3 to 15.4) compared with D2O. DXA fat mass (%) results were more consistent although DXA systematically overestimated fat mass by 4% to 5% compared with D2O. Compared with D2O, ADP does not accurately assess percent fat mass in children aged 3 to 5 years. Thus, D2O, DXA, or quantitative nuclear magnetic resonance may be considered better options for assessing fat mass in young children. [Copyright &y& Elsevier]

Background:Air-displacement plethysmography (ADP) may be a valid and practical technique to assess body composition in a clinical setting.Objective:This study aimed to assess longitudinal changes in body composition using ADP and to compare it with the deuterium dilution technique.Design:The study was a 6-months dietary intervention, consisting of four phases. The first month, subjects were fed in energy balance (phase I). This was followed by 1 month with an energy intake of 33% of energy requirements (phase II), followed by 2 months at 67% of energy requirements (phase III) and 2 months of ad libitum intake (phase IV). Body composition was assessed using ADP (Bod Pod) and deuterium dilution at baseline and at the end of each phase. The baseline analysis included 111 subjects (88 female). Sixty-one subjects (50 female) completed all measurements and were included in the longitudinal analysis.Results:At baseline, the fat mass (FM) as assessed with the Bod Pod was on average 2.3±4.2 kg (mean±2 s.d.) higher than that assessed with deuterium dilution. The difference in FM between techniques increased significantly with increasing FM (R2=0.23; P<0.001). Both techniques showed significant changes in FM over time P<0.001). On average, FM as assessed with the Bod Pod was 2.0 kg higher than with deuterium dilution (P<0.001). During phase II, there was a significant interaction between time and method, meaning that the Bod Pod showed a larger decrease in FM than deuterium dilution.Conclusions:The Bod Pod was able to detect all changes in the body composition, but consistently measured a higher FM than deuterium dilution. [ABSTRACT FROM AUTHOR]

Abstract: Objective: This study compared body composition estimates using deuterium dilution, multiple-frequency bioelectrical impedance analysis (BIA), and skinfold thickness techniques in a group of Cameroonian lactating women. Methods: Body fat, fat-free mass, and total body water in 44 Cameroonian lactating women (2.63 ± 1.31 mo postpartum) were assessed by deuterium dilution, the Siri or black-specific derived Durnin-Womerley equation, and 12 BIA-prediction equations developed in samples of subjects of white, black, black-and-white, or unspecified racial background, respectively. Results: Compared with deuterium dilution, anthropometry and BIA-based predictive equations overestimated body fat by 2.7 to 11.7 kg; thus, fat-free mass and total body water were underestimated. In all cases, the significant biases resulted in large 95% limits of agreement, yielding unacceptable potential bias at the level of the individual. However, the exclusion of suprailiac skinfold in the calculation, yielding to non-significant (P < 0.05) bias, improved the prediction of body composition in Cameroonian lactating women using the Durnin-Womersley and Siri equations. Conclusion: It is essential to adjust the Durnin-Womersley equation before using it in the Siri equation for the prediction of body composition in lactating women. Further development and cross-validation of prediction equations from BIA specific to lactating women is needed. [Copyright &y& Elsevier]

Background: Bioelectrical impedance analysis (BIA) is a simple tool to assess total body water (TBW), from which body composition can be estimated using statistical equations. However, standard BIA equations have not been sufficiently validated during pregnancy, in HIV infection, or in sub-Saharan Africa. We therefore compared TBW estimates from multifrequency BIA with those from the reference method deuterium isotope dilution (Deut) in a cohort of 30 HIV-uninfected and 30 HIV-infected pregnant women from Tanzania. Methods: We enrolled pregnant women presenting for routine antenatal care and collected data on pregnancy outcomes. At each trimester of gestation and once at 10-wk post-partum, we measured maternal anthropometry, TBWBIA, and TBWDeut. Results: TBWBIA was highly correlated at each time point with TBWDeut among HIV-infected (all P ⩽0.001) and HIV-uninfected women (all P <0.0001). During pregnancy, mean TBWBIA progressively underestimated TBWDeut in the overall cohort; trimester-specific differences (mean ±SD) were -1.02 ±2.36 kg, -1.47 ±2.43 kg, and -2.42 ±2.63 kg, respectively. The difference at 10-wk postpartum was small (-0.24 ±2.07 kg). In Bland-Altman and regression models, TBWBIA was subject to a systematic predictive bias at each antenatal and postnatal time point (all P ⩽0.038). Among HIV-positive women, TBWDeut measured during the first (P =0.02) and second trimester (P =0.03) was positively related to birthweight. Conclusions: The validity of current BIA equations to assess TBW during pregnancy and in the postpartum period among women from sub-Saharan Africa remains uncertain. Deuterium dilution may assess aspects of maternal body composition relevant for pregnancy outcomes among HIV-infected women. [ABSTRACT FROM AUTHOR]

Water homeostasis is essential for life and optimal function and considerable interest surrounds the issue of recommendations for water consumption in healthy individuals. Objective data on water turnover in free-living individuals are limited, however. The aim of the present work was to measure water turnover in children and young adults using isotopically labeled water to provide objective data on magnitude and variability in relation to body weight, fat-free mass and physical activity level. Water turnover was measured by deuterated water dilution in 91 healthy children (40 boys, 51 girls; age 5-14 years) and 109 healthy young adults (80 women, 29 men; age 18-27 years) with a wide range of body mass index (13.3-51.8 kg/m(2)) and percent body fat (6.1-59.3%). Total energy expenditure (TEE) and resting metabolic rate were measured by the doubly labeled water technique and indirect calorimetry, respectively. Water turnover was 1.77 ± 0.57 (SD), 1.79 ± 0.44, 2.85 ± 0.82, and 3.90 ± 0.81 L/day in girls, boys, women, and men, respectively. Water turnover indexed to body surface area did not differ significantly between girls and women but was higher in men than boys. Water turnover indexed to TEE was 0.8 mL/kcal in girls and boys and 1.0 mL/kcal in women and men. This study provides objective data on water turnover for children and young adults in a temperate climate and shows that anthropometric parameters can account for the variation between girls, boys and women but not between these groups and the more active men. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the accuracy of clinical methods to estimate body fat (%BF) in people who take weight-inducing atypical antipsychotic medications. Forty-seven people (35 males, 12 females) with previously diagnosed psychotic illness who had been taking atypical antipsychotic medications for more than 6 months took part in this study. Percentage body fat was estimated using bioelectrical impedance analysis (BIA) and anthropometry from previously published prediction equations and compared with that measured using the deuterium dilution technique which served as the criterion measure. Bland-Altman analyses were used to assess the agreement between measures. In the males, %BF determined using BIA with the Lukaski equation was the only clinical method with mean differences that were not significant from criterion values. While in the females, %BF determined from BMI was the only method that was significantly different from the criterion values. All of the methods of estimating %BF except Watson equations provided consistent estimates across the weight range. Therefore, this study suggests that in a group of people who predominantly had schizophrenia and were taking atypical antipsychotic medications, BIA using the equation of Lukaski was the best indicator of %BF, although on an individual basis the accuracy was poor. BMI underestimated %BF to a greater significant extent than BIA. The use of BIA rather than BMI may provide a better indicator of adiposity in people who take weight inducing antipsychotic medications. [ABSTRACT FROM AUTHOR]

Summary: Background & aims: No information is available on the validity of impedance-based equations for the prediction of body composition in Cameroonian HIV-infected patients treated with antiretroviral drugs. Equations for the prediction of total body water (TBW) have the tendency to be population-specific, and this may be due to biological factors, such as variable body geometry and physiological state. We tested the validity of equations derived from different racial backgrounds for predicting TBW from bioelectrical impedance analysis measurements. Method: The TBW content of 56 Cameroonian HIV patients (19 men and 37 women) treated with the first-line ARV regimen was measured by deuterium dilution and compared with those predicted by 12 equations developed respectively in samples of white, black, black and white, or unspecified racial background subjects. Results: Pure errors in predicting TBW showed acceptable value for all the equations tested. Four equations (three from whites and one from blacks and whites) yielded a non-significant bias; however, equation H which presented the narrower 95% confidence interval and the smaller pure error was recommended for the prediction of TBW in Cameroonian HIV-infected patients treated with antiretroviral drugs. In all other cases, we observed either an overestimation or underestimation of TBW with variable bias values. Conclusion: The absence of a clear trend in cross-validation among equations according to their origin and the probable effect of physiological state should encourage further exploration of the causes of the lack of validity. [Copyright &y& Elsevier]

Background. Previous studies have compared body composition (BC) assessment methods in obese patients, however there is lack of literature on the comparison of bedside BC methods in obese diabetic subjects, particularly with respect to regional body fat (BF) distribution. The aim of this study was: to estimate the differences in fat mass (FM) using bioelectrical impedance (BIA), skinfold thickness (SFT) and body mass index (BMI) in comparison to the reference method of deuterium oxide (D2O) dilution in obese patients with and without type 2 diabetes (DM); to relate the differences in percentage of fat mass (%FM) to the regional body fat (BF) distribution. Materials and methods. BC was estimated using anthropometry, D2O, BIA, SFT, and BMI was used to calculate fat content in 94 obese patients, of whom 53 participants had type 2 DM (obese DM). Results. BIA and SFT yielded 5.2% and 6.1% lower (p < 0.001) results of %FM, respectively, in obese without DM, and 3.9% (p = 0.01) and 2.8% (p = 0.037) lower results in obese DM group, accordingly, compared to D2O dilution, while %FM calculated using BMI was higher by 3.2% (p = 0.045) in obese DM group. The difference estimated by BIA was constant for all the obesity classes, whereas for SFT increased in parallel with body weight. Fat in legs, arms, trunk area and waist to hip ratio were all important determinants for the difference in %FM between D2O dilution and bedside methods. Conclusions. The BIA and SFT underestimated FM in obese with and without DM, while BMI overestimated FM in obese DM group in comparison to D2O. The differences in regional body fat distribution were significant predictor variables, influencing the accuracy of the %FM estimated in all the patient groups. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Scant information exists about the changes in body composition of children during the first months of chemotherapy. These changes can be determined by using a better method than the body mass index. This study compared the changes of body composition by dilution of deuterium oxide in Mexican children with lymphoma and with solid tumors. Methods: Seventeen patients were enrolled and classified as having lymphoma or solid tumor. Body composition was measured by a deuterium dilution technique after the first course of chemotherapy and again after 2 and 6 mo of therapy. Data were compared by means of paired t and Student’s t tests. Simple linear regression was applied to examine the relation between age and changes in fat mass (FM) and fat-free mass (FFM). Results: The groups were similar at baseline. Six months after initiation of chemotherapy, weight and height had increased (P < 0.05) in the lymphoma group, whereas only height had increased in the solid-tumor group; total body water, FM, and FFM increased in the lymphoma group (P < 0.01) but not in the solid-tumor group. Age did not influence FM or FFM in either group. Conclusion: In children with lymphoma whose treatment included corticosteroid use, increase in FM content was demonstrated during the first 6 mo of treatment. In patients with solid tumors, FM content did not change during treatment. With an increase in FM content, one should bear in mind that overweight and obesity may result in cardiovascular disease and development of breast cancer in adult life. [Copyright &y& Elsevier]

Background: Most techniques for measuring body composition are based on 2-component models (2-CMs) and depend on assumptions relating to the constancy of the density (DFFM) and hydration fraction (HFFFM) of fat-free mass (FFM). Objectives: The objectives were to determine whether these assumptions are systematically violated in patients with cirrhosis and to assess the validity of the estimates of body composition obtained in these patients by using 2-CM techniques. Design: Body composition was assessed by using a 4-component model (4-CM), which was based on data obtained from densitometry, deuterium dilution, and dual-energy X-ray absorptiometry, in 20 patients with cirrhosis who had no evidence of fluid retention and in 20 pair-matched healthy control subjects. The results were compared with those obtained by using "reference" and "bedside" 2-CM techniques. Results: The mean ( ± SD) DFFM was significantly lower in the patients with cirrhosis (1.091 ± 0.008 compared with 1.100 ± 0.006 kg/L; P < 0.001); no significant difference in HFFFM was observed between the patients and control subjects (74.5 ±2.6 compared with 73.5 ± 2.1), although there was greater variability in the patients. Significant differences were observed in the body-composition variables obtained by using the "reference" 2-CM techniques compared with the 4-CM-the 95% limits of agreement in the patients with cirrhosis exceeded 5% body fat and 3 kg FFM; the corresponding values for the "bedside" 2-CM techniques were 11% body fat and 7.5 kg FFM. Conclusions: Assumptions relating to the constancy of the DFFM and HFFFM are violated in patients with cirrhosis. Thus, standard 2-CM techniques provide inaccurate body composition estimates in this patient population. [ABSTRACT FROM AUTHOR]

Background: Little information is available on the validity of simple and indirect body-composition methods in non-Western populations. Equations for predicting body composition are population specific, and body composition differs between blacks and whites. Objective: We tested the hypothesis that the validity of equations for predicting total body water (TBW) from bioelectrical impedance analysis measurements is likely to depend on the racial background of the group from which the equations were derived. Design: The hypothesis was tested by comparing, in 36 African women, TBW values measured by deuterium dilution with those predicted by 23 equations developed in white, African American, or African subjects. These cross-validations in our African sample were also compared, whenever possible, with results from other studies in black subjects. Results: Errors in predicting TBW showed acceptable values (1.3- 1.9 kg) in all cases, whereas a large range of bias (0.2- 6.1 kg) was observed independently of the ethnic origin of the sample from which the equations were derived. Three equations (2 from whites and 1 from blacks) showed non significant bias and could be used in Africans. In all other cases, we observed either an overestimation or underestimation of TBW with variable bias values, regardless of racial background, yielding no clear trend for validity as a function of ethnic origin. Conclusions: The findings of this cross-validation study emphasize the need for further fundamental research to explore the causes of the poor validity of TBW prediction equations across populations rather than the need to develop new prediction equations for use in Africa. [ABSTRACT FROM AUTHOR]

OBJECTIVE:: Most body composition techniques assume constant properties of the fat-free mass (FFM), such as hydration, density and mineralisation. Previous studies suggested that FFM composition may change in childhood obesity; however, this issue has not been investigated in detail. AIM:: To compare FFM composition in obese and nonobese children. DESIGN:: Observational matched case-control analyses. SUBJECTS:: A total of 28 obese children (13 boys, 15 girls) and 22 nonobese children (10 boys, 12 girls) aged 7-14?y. Obesity was defined as body mass index centile>95. METHODS:: Measurements were made of weight, height, total body water, and body volume. Bone mineral content was estimated in a subsample. Body composition was calculated using three- and four-component models. RESULTS:: According to the three-component model (n=22 matched pairs), obese children had greater hydration (P<0.05), and reduced density (P=0.057) of FFM. According to the four component model (n=11 pairs), obese children had greater hydration (P<0.01) and reduced density (P<0.002) of FFM. The mineralisation of FFM was increased, but not significantly so. CONCLUSION:: The greater hydration and reduced density of FFM of obese children should be taken into account if body composition is to be measured with optimum accuracy during treatment programmes. These differences may be addressed by using multicomponent rather than two-component models of body composition. Although the greater mineralisation of FFM in obese children was not significant in the present study, the four-component model is best able to address the combined differences in hydration and mineralisation that occur in childhood obesity.International Journal of Obesity (2005) 29, 29-36. doi:10.1038/sj.ijo.0802834 Published online 2 November 2004 [ABSTRACT FROM AUTHOR]

Background: The accurate measurement of body composition is useful in assessments of infant growth and nutritional status. Objective: This study evaluated the reliability and accuracy of a new air-displacement plethysmography (ADP) system for bodycomposition assessment in infants. Design: Between- and within-day reliability was assessed by comparing the percentage body fat (%BF) obtained on consecutive days and on the same day, respectively, in 36 full-term infants. Accuracy was assessed by comparing %BF measured with the use of ADP and %BF measured with the use of deuterium (2H2O) dilution in 53 infants. Results: There were no significant differences in%BFbetween days (-0.50 ± 1.21%BF) or within days (0.16 ± 1.44%BF). Mean between- and within-day test-retest SDs of 0.69 and 0.72%BF, respectively, indicated excellent reliability. The %BF measurements obtained by using ADP were not significantly influenced by infant behavioral state. Mean %BF obtained by using ADP (20.32%BF) did not differ significantly from that obtained by using 2H2Odilution (20.39%BF), and the regression line [%BF(2H2O) = 0.851%BF (ADP) + 3.094] gave a high R2 (0.76) and a low SEE (3.26). The 95% limits of agreement between ADP and 2H2O (-6.84%BF, 6.71%BF) were narrower than those reported for other bodycomposition techniques used in infants. Individual differences between the 2 methods were not a function of body mass or fatness. Conclusion: ADP is a reliable and accurate instrument for determining %BF in infants, and it has the potential for use in both research and clinical settings. [ABSTRACT FROM AUTHOR]

To validate two practical methods of body composition measurement, total body water percent (TBW) was measured using a) anthropometric equations, b) bioelectrical impedance analysis (BIA) and c) deuterium oxide (D2O) dilution (reference method) in 10 children (7 boys, 3 girls) from among urban poor in Kolkata, India (age : 8 m to 60 m, mean ± SD = 29.0 ± 18.82). The deuterium dilution (D2O) and the BIA method showed close concordance for estimation of TBW% (mean ± SD of difference of paired values: 0.186 ± 1.567, r = 0.81). Similarly, a close concordance between D2O and anthropometric method for TBW% (mean ± SD of difference of paired values: 0.155 ± 0.998, r = 0.93) was shown. Of the two methods, anthropometry appeared more accurate, useful and expedient than the BIA method, although the difference was not significant. However, unlike anthropometry BIA can also be used to measure TBW and other body compartments and in some disease states. [Copyright &y& Elsevier]

Background: The body composition was measured in 30 female Singapore Chinese and 34 female Dutch Caucasians aged (mean ± SD) 22.7 ± 3.6 years and in 39 male Singapore Chinese and 39 male Dutch Caucasians aged 23.3 ± 3.2 years. Methods: The body fat percentage (BF%) was measured using densitometry and deuterium oxide dilution as well as a chemical four-compartment model, including fat mass, water, mineral, and protein. The chemical composition of the fat-free mass (FFM) and its density were calculated. Results: Mean body mass index (kg/m[sup 2] ) and BF% based on the four-compartment model in the four subgroups were 20.3 ± 1.5 and 29.7 ± 5.3 for the Singapore Chinese females, 22.1 ± 1.2 and 28.9 ± 5.2 for the Dutch females, 21.5 ± 2.5 and 19.4 ± 6.1 for the Singapore males, and 22.2 ± 1.8 and 15.8 ± 4.9 for the Dutch males. The contributions to the FFM of water, protein, and mineral were, respectively, 72.8 ± 1.5, 19.2 ± 1.8, and 7.9 ± 0.8% for the Singaporean females and 74.2 ± 1.4, 18.3 ± 1.5, and 7.6 ± 0.5% for the Dutch females. In males these figures were 73.2 ± 1.7, 19.6 ± 1.7, and 7.3 ± 0.5% for the Singaporeans and 72.9 ± 1.4, 20.5 ± 1.4, and 6.6 ± 0.5% for the Dutch. In females, these figures were for all components significantly different between the ethnic groups; in males the differences were significant for protein and mineral only. The calculated densities (kg/l) of the FFM were 1.1074 ± 0.0057, 1.1012 ± 0.0051, 1.1027 ± 0.0065, and 1.1004 ± 0.0055 for the Chinese females, Caucasian females, Chinese males, and Caucasian males, respectively. Conclusions: Although it cannot be excluded that the differences in density and composition of the FFM are due to methodological differences between the study sites, the findings may have consequences for the validity of single (reference) methods due to violation of normally used assumptions. The findings explain the observed underestimation of BF% from density using Siri’s formula in the Chinese subjects, especially in females. The use of deuterium oxide as a single method to determine the BF% resulted in a smaller bias than densitometry (overall 1.6 ± 2.0% for densitometry, 0.3 ± 1.7% for deuterium dilution), suggesting that the deuterium oxide method may be more suitable as a single method in comparative body composition studies.Copyright © 2000 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Single-frequency bioelectrical-impedance analyses (BIA) and bioelectrical spectroscopy (modeling multifrequency measurements; BIS) were validated as methods to predict body water (BW) compartments in 29 healthy adults. Total body water (TBW) and extracellular water (ECW) were determined by deuterium- and bromide-dilution techniques. Contribution of BIA to anthropometry and influence of the position of electrodes were examined. Stepwise-regression analysis revealed that inclusion of BIA to anthropometric data greatly improved the fit with BW compartments. Highly significant correlations were observed between BIS and BW compartments (TBW: r² = 0.98, SEE = 1.2; ECW: r² = 0.95, SEE = 0.6). Cross-correlation (14 males, and 15 females) indicated predictive potential of the method. Results from BIS and BIA were comparable, but it is argued that BIS has the potential of improved standardization of the method. [ABSTRACT FROM AUTHOR]