Validity of methods of body composition assessment in young and older men and women

Effect of acute meal and long-term intake of a Mediterranean Diet providing different amounts of carbohydrates on physical performance and biomarkers in non-professional strength athletes

The study aims to evaluate the effect of an acute meal and long-term intake of Mediterranean Diet (MD) on different parameters such as strength, physical performance, body composition and blood markers in a group of non-professional athletes who practice a strength activity. Thirteen volunteers completed two 8-week dietary interventions in a randomised, cross-over design. Also an acute study was performed. Subjects received a MD High in carbohydrates, characterised by at least five portions of pasta/week and an average 55-60% of daily energy derived from carbohydrates, versus an MD reduced in carbohydrates, with less than two portions of pasta/week and an average of 40-45% of daily energy provided by carbohydrates. Mainly, data did not show significant differences for the parameters analysed, except for Elbow Flexor maximum voluntary contraction (p = .039). Results enlighten that increasing total carbohydrates intake, as typically in the MD, does not negatively affect physical performance, body composition and strength.

Comparison of four quick and reliable methods of assessing body fat appropriate for clinical settings among young, middle-age, and older healthy male and female adults

[Purpose] Compare four quick (approximately 60 s), reliable methods of assessing %body-fat (%BF) among young (Y, 18-34 years), middle-age (M, 35-59 years), and older (O, 60-88 years) healthy-adults. [Participants and Methods] One-hundred-eighty healthy males-and-females were equally (n=30) divided into Y, M, and O age groups to assess %BF. The %BF methods were: 1) Bioelectrical-impedance-Inbody770 (IB)-criterion reference; 2) Body-mass-index (BMI); 3) Abdominal-and-hip circumferences (CIR); and 4) Skinfold (SF). [Results] %BF were significantly different among the four body-fat methods and among the three age-groups for both males-and-females. %BF among IB,BMI,CIR, and SF were, respectively, 15.7 ± 4.7%, 19.6 ± 3.2%, 17.3 ± 3.5%, and 12.1 ± 4.1% for Y-males; 18.3 ± 5.7%, 22.8 ± 3.6%, 19.6 ± 3.6%, and 15.6 ± 4.5% for M-males; 24.4 ± 6.5%, 25.8 ± 3.3%, 24.0 ± 4.5%, and 20.0 ± 4.1% for O-males; 24.9 ± 6.9%, 28.9 ± 4.1%, 29.4 ± 4.6%, and 22.4 ± 6.3% for Y-females; 25.1 ± 7.0%, 31.4 ± 4.7%, 33.0 ± 4.5%, and 25.0 ± 4.5% for M-females; 35.1 ± 6.3%, 35.5 ± 4.3%, 38.4 ± 4.8%, and 26.4 ± 3.7% for O-females. [Conclusion]The most accurate %BF-methods to use in clinical settings are CIR for Y-and-M-males, CIR and BMI for O-males, SF for Y-and M-females, and BMI for O-females. The least accurate %BF methods are BMI and SF for Y-males, BMI for M-males, SF for O-males, BMI and CIR for Y-and M-females, and SF for O-females. While all 4-methods of assessing %BF can easily and quickly be employed in clinical settings, some methods significantly underestimate or overestimate %BF and yield different results among varying age groups and sex. These findings help identify people at early health risk of cardiometabolic disease, with O-males and O-females at higher risk.

Temporal trends in obesity defined by the relative fat mass (RFM) index among adults in the United States from 1999 to 2020: a population-based study

OBJECTIVES

The body mass index (BMI) largely underestimates excess body fat, suggesting that the prevalence of obesity could be underestimated. Biologically, women are known to have higher body fat than men. This study aimed to compare the temporal trends in general obesity by sex, ethnicity and age among adults in the USA using the relative fat mass (RFM), a validated surrogate for whole-body fat percentage and BMI.

DESIGN

Population-based study.

SETTING

US National Health and Nutrition Examination Survey, from 1999-2000 to 2017-March 2020.

PARTICIPANTS

A representative sample of adults 20-79 years in the USA.

MAIN OUTCOME MEASURES

Age-adjusted prevalence of general obesity. RFM-defined obesity was diagnosed using validated cut-offs to predict all-cause mortality: RFM≥40% for women and ≥30% for men. BMI-defined obesity was diagnosed using a cut-off of 30 kg/m2.

RESULTS

Analysis included data from 47 667 adults. Among women, RFM-defined obesity prevalence was 64.7% (95% CI 62.1% to 67.3%) in 2017-2020, a linear increase of 13.9 percentage points (95% CI 9.0% to 18.9%; p<0.001) relative to 1999-2000. In contrast, the prevalence of BMI-defined obesity was 42.2% (95% CI 39.4% to 45.0%) in 2017-2020. Among men, the corresponding RFM-defined obesity prevalence was 45.8% (95% CI 42.0% to 49.7%), a linear increase of 12.0 percentage points (95% CI 6.6% to 17.3%; p<0.001). In contrast, the prevalence of BMI-defined obesity was 42.0 (95% CI 37.8% to 46.3%). The highest prevalence of RFM-defined obesity across years was observed in older adults (60-79 years) and Mexican Americans, in women and men. Conversely, the highest prevalence of BMI-defined obesity across years was observed in middle-age (40-59 years) and older adults, and in African American women.

CONCLUSIONS

The use of a surrogate for whole-body fat percentage revealed a much higher prevalence of general obesity in the USA from 1999 to 2020, particularly among women, than that estimated using BMI, and detected a disproportionate higher prevalence of general obesity in older adults and Mexican Americans.

Influence of age and sex on alcohol pharmacokinetics and subjective pharmacodynamic responses following intravenous alcohol exposure in humans

There are substantial inter-individual variations in alcohol metabolism and response that are likely due to sex and age; however, these are not well understood. We investigated age and sex influences on alcohol elimination rate (AER) and subjective responses following intravenous (IV) administration in non-dependent drinkers. Participants underwent a 2-session study where they received IV alcohol (target breath alcohol level: 0.05 g%) and placebo in counter-balanced order. AER was higher in males than in females across age groups. These differences were partly explained by sex differences in lean body mass and liver volume. Alcohol significantly increased peak feelings of high, intoxication, drug-effects, liking-effects, and wanting-more, with no major sex differences. There were no age-related differences in feelings of high and intoxication; however, the older group reported significantly lower peak liking-effects and stimulation responses than the younger group. These findings highlight the significant impact of sex and age as sources of variability in the clinical pharmacology of alcohol.

Effects of a zero-gravity treadmill on body composition and cardiorespiratory fitness after Achilles surgery in a Masters runner

Zero-gravity treadmills allow alterations in training load. Data are lacking on the utilization of this strategy to allow injured Masters-level athletes to return to activity and regain their fitness. A 6-week training program was designed for a 39-year-old male runner recovering from Achilles surgery using a zero-gravity treadmill. Three training sessions per week were performed with gradually increasing loads. Cardiopulmonary exercise testing and bioelectrical impedance analysis were performed before and after program completion. Following the training program, the athlete was able to return to full weight-bearing running. On cardiopulmonary exercise testing, there were improvements in peak oxygen consumption (42.9 vs 47.3 mL/min/kg; 118.6% vs 130.5% of predicted). On bioelectrical impedance analysis, there were small improvements in total weight, skeletal muscle mass, and adiposity felt to be within the standard of error for bioelectrical impedance analysis. In conclusion, load-altering exercise may be helpful for the Masters-level athlete recovering from Achilles tendon surgery.

Body composition assessment in children with inflammatory bowel disease: A comparison of different methods

AIM

To assess different techniques to measure body composition in paediatric patients with inflammatory bowel disease using dual energy X-ray absorptiometry as a reference method. We hypothesised that a three-compartment model may demonstrate superiority over other methods as skinfold thickness equations and bioelectrical impedance analysis.

METHODS

Body composition was assessed using skinfold thickness equations, bioelectrical impedance analysis and the three-compartment model. Data obtained with these methods were compared to the results obtained by dual energy X-ray absorptiometry. Statistical analysis was performed using Spearman's correlation and Bland-Altman's limits of agreement method.

RESULTS

Twenty-one paediatric patients with inflammatory bowel disease were included: 11 females and 10 males; mean age for the entire group: 14.3 years, range 12-16 years. In children with inflammatory bowel disease, skinfold thickness equations, bioelectrical impedance analysis and the three-compartment model showed reliable measurements with small differences in the percentage of total body fat and good limits of agreements.

CONCLUSION

The assessment of body composition using bioelectrical impedance analysis provides a valid and accurate method in children with inflammatory bowel disease as compared to dual energy X-ray absorptiometry. In the future, superiority of 3-compartment model in research and clinical settings of nutritional intervention and disease status in children with inflammatory bowel disease remains to be demonstrated.

Agreement between laboratory methods and the 4-compartment model in assessing fat mass in obese older Hispanic-American adults

BACKGROUND/OBJECTIVES

Densitometry (Siri's and Brožek's equations), hydrometry (by the deuterium dilution technique), and dual-energy X-ray absorptiometry (DXA) are three methods for estimating body composition. However, because they are all based on certain assumptions, they may not be applicable to aged and obese subjects due to changes in their body composition. Hence, the validity of these "laboratory methods" could be affected in obese older people. The main aim was to assess the agreement between densitometry, hydrometry, and DXA with the 4-compartment (4C) model to estimate fat mass (FM) in obese older Hispanic-American adults. As secondary goals, we explored whether the bias in densitometry and hydrometry results could be improved by modifying the assumptions regarding fat-free mass (FFM) density and hydration factor (HF) values, respectively. In the case of DXA, we explored the factors that contribute to bias.

SUBJECTS/METHODS

This is a cross-sectional study based on a sample of 171 obese subjects aged ≥60 years from 3 regions of northern Mexico. Body composition was assessed by the 4C model as the reference method and by all three laboratory methods. Agreement of the latter with the 4C model was probed by Bland and Altman analysis, a paired sample t-test, and simple linear regression analyses. In addition, the mean FFM density estimated in this sample, and HF values (published previously) of 0.737 and 0.753 for obese older Hispanic-American men and women, respectively, were considered as ethnic- and gender-specific values. These values were used to modify the densitometric and hydrometric equations in order to improve their bias. Finally, we tested whether the hydration status and indirect markers of adiposity are contributing factors to the bias of DXA using multiple linear regression analysis.

RESULTS

Siri's equation overestimated FM by 0.57 kg (p < 0.01), while Brožek's equation, hydrometry, and DXA underestimated it by 1.24 kg, 0.89 kg, and 0.79 kg (p < 0.01), respectively, compared to the 4C model. The bias in the densitometry and hydrometry results was eliminated by substituting the ethnic- and gender-specific values into the equations. Finally, we found that hip circumference contributes to the bias in DXA.

CONCLUSION

The densitometry, hydrometry, and DXA methods are not interchangeable with the 4C model for assessing fat mass in obese, older Hispanic-American adults. The lack of agreement could indicate that the assumptions of each method do not apply to this population.

Examining Race-Related Error in Two-Compartment Models of Body Composition Assessment: A Systematic Review and Meta-Analysis

BACKGROUND

The Brozek and Siri formulas estimate relative adiposity (%Fat) from total body density (Db) using a 2-compartment (2C) model. Racial/ethnic differences in Db have been reported, along with subsequent errors in estimated %Fat.

OBJECTIVE

The primary aim of this systematic review and meta-analysis was to examine potential race/ethnic differences in the accuracy of the Brozek and Siri 2C formulas using aggregate-level data.

METHODS

Peer-reviewed studies available in English that provided 2C and 4C estimates of %Fat were located using searches of the PubMed (n = 150), Scopus (n = 170), and Web of Science (n = 138) online electronic databases. Random-effects models were used to determine potential differences between racial groups using a mean ES and 95% confidence intervals.

RESULTS

The cumulative results from 78 effects indicate that the relative accuracy of the Brozek equation did not vary between racial groups (between group p = 0.053). In contrast, the Siri equation slightly underestimated %Fat for Asian adults (ESWMD = -1.40%, 95%CI -2.33% to -0.46%; p = 0.004) and Black adults (ESWMD = -1.10%, 95%CI -2.11% to -0.08%; p = 0.034), with no significant differences observed in Hispanic adults (ESWMD = 0.64%, 95%CI -1.02% to 2.31%; p = 0.448) and White adults (ESWMD = 0.08%, 95%CI -0.42% to 0.57%; p = 0.766) (between group p = 0.019).

CONCLUSION

Small, but statistically significant, error was found between racial groups when estimating %Fat using the 2C Siri equation when compared to 4C models. However, the observed error due to race/ethnicity appears to be of little clinical or practical significance when using either equation.

Body fat percentage assessment by skinfold equation, bioimpedance and densitometry in older adults

Background

Body fat estimation allows measuring changes over time attributed to interventions and treatments in different settings such as hospitals, clinical practice, nursing homes and research. However, only few studies have compared different body fat estimation methods in older adults with inconsistent results. We estimated body fat percentage (%BF) and the level of agreement among dual energy X-ray absorptiometry (DXA), bioelectrical impedance (BIA) and Durnin & Womersley’s skinfold eq. (SF) in older Brazilian adults aged 60 years and older from the Elderly Project Goiânia, Brazil.

Methods

The analytical sample comprised of 132 participants who had DXA data. The level of agreement for the %BF estimated by BIA, SF and DXA i.e. reference method, was examined using Bland and Altman’s and Lin’s plot.

Results

Overall, women had higher body mass index and %BF values measured by all three methods used. BIA and SF equation showed strong concordance to estimate body fat percentage in all participants (CCC = 0.857 and 0.861, respectively) and among women (CCC = 0.788 and 0.726, respectively) when compared to DXA. However, both methods underestimated body fat percentage in women and men with high body fat percentage. A strong level of agreement was observed between DXA and the anthropometric equation developed by Durnin & Womersley in men (CCC = 0.846), while BIA had a moderate concordance (CCC = 0.505) in this group.

Conclusion

The examined methods indicated different body fat estimates. However, the best agreement was observed between DXA and the anthropometric SF equation for men. Future research in older adults should develop new SF equations considering different ethnic groups.

The Prediction of Body Composition in African Americans From Spine and Hip Dual-Energy Absorptiometry

Body composition, the makeup of the body's fat and lean tissue, is associated with important health outcomes and provides useful clinical information. Although body composition can be measured with total body dual-energy X-ray absorptiometry (DXA), this is rarely performed. As an alternative to total body DXA measurement, methods for estimation of body composition have been developed. These methods use soft tissue measures from spine and hip DXA to predict body composition and include prediction equations previously published by Leslie and proprietary equations within General Electric densitometry software. However, these estimates have not been tested in African Americans (AA), an ethnicity with a different distribution of fat than Caucasians (CA). Therefore, we examined the performance of the existing models in 99 CA and 162 AA subjects over the age of 40 who had total body, spine, and hip DXA measurements. We observed that existing models estimated body composition well in CA but underestimated fat mass and overestimated lean mass in AA. AA subjects were then randomly divided into 2 equal-sized subgroups-the first to develop new prediction equations and the second to independently validate them. We found that body composition can be more accurately estimated using either a new model that we derived in AA subjects using backward stepwise elimination or by adding a fixed offset for AA to the previously published model. Our results demonstrate that body composition estimates from spine and hip DXA require consideration of race/ethnicity.

Relative fat mass (RFM) as a new estimator of whole-body fat percentage ─ A cross-sectional study in American adult individuals

High whole-body fat percentage is independently associated with increased mortality. We aimed to identify a simple anthropometric linear equation that is more accurate than the body mass index (BMI) to estimate whole-body fat percentage among adult individuals. National Health and Nutrition Examination Survey (NHANES) 1999–2004 data (n = 12,581) were used for model development and NHANES 2005–2006 data (n = 3,456) were used for model validation. From the 365 anthropometric indices generated, the final selected equation was as follows: 64 − (20 × height/waist circumference) + (12 × sex), named as the relative fat mass (RFM); sex = 0 for men and 1 for women. In the validation dataset, compared with BMI, RFM better predicted whole-body fat percentage, measured by dual energy X-ray absorptiometry (DXA), among women and men. RFM showed better accuracy than the BMI and had fewer false negative cases of body fat-defined obesity among women and men. RFM reduced total obesity misclassification among all women and all men and, overall, among Mexican-Americans, European-Americans and African-Americans. In the population studied, the suggested RFM was more accurate than BMI to estimate whole-body fat percentage among women and men and improved body fat-defined obesity misclassification among American adult individuals of Mexican, European or African ethnicity.

Aerobic exercise elevates markers of angiogenesis and macrophage IL-6 gene expression in the subcutaneous adipose tissue of overweight-to-obese adults

Alterations in the inflammatory state, metabolic function, and structure of subcutaneous adipose tissue (SAT) can impact the development of insulin resistance in obesity. Exercise can improve metabolic health in obesity, but the effects of exercise on SAT are not well known. The purpose of this study was to examine the effects of acute exercise and habitual exercise training on mRNA expression of markers of lipid metabolism, inflammation, fibrosis, and hypoxia/angiogenesis in SAT, as well as adipocyte cell size. We recruited overweight-to-obese adults who exercised regularly (ACTIVE: n = 8) or were sedentary (SED: n = 12). The groups were well matched for age (27 ± 1 vs. 24 ± 2 yr), body mass index (29 ± 1 vs. 27 ± 1 kg/m²), and body composition (30 ± 1 vs. 29 ± 1% body fat), but as expected, cardiorespiratory fitness was greater in ACTIVE vs. SED (V̇o_2peak: 51 ± 3 vs. 42 ± 1 ml·kg fat-free mass^-1·min^-1; P = 0.01). Abdominal SAT biopsy samples were obtained before and 1 h after a single session of aerobic exercise (60 min at ~65% V̇o_2peak). The exercise session increased SAT mRNA expression of VEGFA, an important regulator of angiogenic processes, in both groups. In addition, SAT from ACTIVE subjects had greater mRNA expression of the endothelial cell marker CD31 compared with SED, which may be a cumulative effect of the transient increases in VEGFA with regular exercise. We also magnetically sorted CD14+ immune cells from SAT samples and found that IL-6 expression was elevated in ACTIVE compared with SED. In conclusion, exercise initiates increases in factors related to angiogenic processes and may promote alterations in macrophage inflammation in SAT.NEW & NOTEWORTHY Acute exercise in overweight/obese adults increased subcutaneous adipose tissue (SAT) mRNA expression of VEGFA, an important regulator of angiogenesis and capillary growth. In addition, subjects that regularly exercise had elevated SAT CD31 mRNA expression and elevated IL-6 mRNA in adipose tissue macrophages compared with nonexercisers. This study demonstrates that aerobic exercise may alter processes related to whole body metabolic outcomes in obesity, such as angiogenesis and immune response, in the SAT of overweight/obese adults.

Weight and fat distribution in patients taking valproate: a valproate-discordant gender-matched twin and sibling pair study

OBJECTIVES

Chronic treatment with valproate (VPA) is commonly associated with weight gain, which potentially has important health implications, in particular increased central fat distribution. We utilized a VPA-discordant same-sex, twin and matched sibling pair study design to primarily examine for differences in fat distribution between patients with epilepsy treated with VPA compared to their matched twin or sibling control. Weight, blood pressure, and leptin levels were assessed.

METHODS

Height, weight, waist and hip measurements, exercise, blood pressure (BP), and serum leptin levels were measured. Body composition was measured using dual-energy x-ray absorptiometry (DXA). Abdominal fat was expressed as a percentage of the abdominal region (AFat%); and of whole body fat (WBF); (AFat%WBF). Mean within-pair differences were assessed (VPA-user and nonuser). Restricted maximum likelihood (REML) linear mixed model analysis was fitted to examine associations of anthropometrics, zygosity, gender, menopausal status, VPA dose and duration, with weight and AFat%.

RESULTS

We studied 19 pairs of VPA-discordant, gender-matched (five male, 14 female) twins and siblings. Mean (standard deviation, SD) duration of therapy for VPA users was 11.0 (7.4) years. There were no statistically significant within-pair differences in age, height, weight, body mass index (BMI), BP, leptin level, WBF, AFat%, or AFat%WBF. For pairs in which VPA-user was treated for >11 years there were statistically significant mean within-pair differences in AFat%, (+7.1%, p = 0.03, n = 10 pairs), mean BP (+11.0 mm Hg, p = 0.006, n = 8 pairs); but not in AFat%WBF. VPA duration was positively associated with weight (estimate +0.98 kg/per year of VPA, p = 0.03); VPA treatment duration and dose were not significantly associated with AFat%.

SIGNIFICANCE

This study demonstrated a relationship between long-term VPA use and abdominal adiposity (AFat%), which could have significant health implications. We recommend ongoing monitoring of weight, BMI, and blood pressure for patients taking VPA.

Acute exercise ameliorates differences in insulin resistance between physically active and sedentary overweight adults

Although regular exercise is associated with reduced cardiometabolic disease risk among overweight adults, it remains unclear whether much of the health benefits of exercise are derived from the most recent session(s) of exercise or if they are the result of adaptations stemming from weeks, months, or even years of training. The purpose of this study was to compare the effects of habitual and acute exercise on key markers of cardiometabolic disease risk in overweight adults. We compared insulin sensitivity index (ISI) using an oral glucose tolerance test, blood pressure (BP), blood lipids, and systemic inflammatory cytokines in 12 overweight to mildly obese adults (BMI: 27-34 kg/m(2)) who exercise regularly (EX; >2.5 h exercise per week) with a well-matched cohort of 12 nonexercisers (Non-EX). Baseline measurements in EX were performed exactly 3 days after exercise, whereas Non-EX remained sedentary. We repeated these measurements the day after a session of exercise in both groups. At baseline, ISI was significantly greater in EX versus Non-EX (3.1 ± 0.2 vs. 2.3 ± 0.2; p = 0.02), but BP, blood lipids, and plasma concentration of the systemic inflammatory cytokines we measured were not different between groups. Acute exercise increased ISI the next morning in Non-EX (2.3 ± 0.2 vs. 2.8 ± 0.3; p = 0.03) but not EX. As a result, ISI was similar between groups the morning after exercise. In summary, exercising regularly was accompanied by a persistent improvement in insulin sensitivity that lasted at least 3 days after exercise in overweight adults, but just one session of exercise increased insulin sensitivity among sedentary overweight adults to levels equivalent to the regular exercisers.

Difference in muscle quality over the adult life span and biological correlates in the Baltimore Longitudinal Study of Aging

OBJECTIVES

To examine differences in a proxy measure of muscle quality across the adult life span and explore potential mechanisms of muscle quality change through identification of cross-sectional correlates of muscle quality.

DESIGN

Cross-sectional study.

SETTING

Baltimore Longitudinal Study of Aging.

PARTICIPANTS

Seven hundred eighty-six individuals with a mean age of 66.3 (range 26-96) (N = 786). A sensitivity analysis was conducted in a subset of participants matched according to sex, muscle mass, and body size.

MEASUREMENTS

Muscle quality was operationalized as the ratio of knee-extension strength (isokinetic dynamometry) to thigh muscle cross-sectional area (computed tomography). Differences in muscle strength, muscle area, and muscle quality ratio with age were evaluated, and the association between the muscle quality ratio and measures reflecting domains of cognitive function, motor control, peripheral nerve function, adiposity, glucose homeostasis, and inflammation were assessed through multivariate regression analyses.

RESULTS

A linear relationship between age and muscle quality ratio was observed, suggesting a gradual decline in muscle quality over the adult life course. Associations were observed between muscle quality ratio and measures of adiposity, as well as peroneal nerve motor conduction velocity, finger tapping speed, and memory performance (P < .01). The association between muscle quality ratio and nerve conduction velocity was maintained after adjustment for anthropometric measurements (P < .05).

CONCLUSION

Muscle quality declines progressively with age over the adult life span and is affected by obesity and neurological factors. Studies are needed to clarify the mechanisms of these associations and their implications for functional outcomes.

A comparison of prediction equations for the estimation of body fat percentage in non-obese and obese older Caucasian adults in the United States

OBJECTIVES

The predictive capabilities of skinfold regression equations are limited across populations and current equations may not be well suited for the prediction of body fat in older adults or obese Americans. The goal of this study was to compare percent body fat (%BF) predicted by several skinfold regression equations to %BF determined by Dual-Energy X-ray Absorptiometry (DXA) in obese and non-obese Caucasian men and women in the United States over the age of 65 years.

DESIGN

A block design was used with two blocks: obesity (non-obese/obese) and gender (male/female). All subjects underwent the same testing procedures in one visit.

SETTING

University of Pittsburgh Clinical and Translation Research Center.

PARTICIPANTS

Seventy-eight older healthy adults were recruited for participation.

MEASUREMENTS

Actual percent body fat was determined from a whole body DXA scan. Estimated percent body fat (%BF) was calculated using skinfold measurements and established regression equations. The predictive accuracy of the regression equations was evaluated by comparing the estimated %BF to the actual %BF measured with DXA using a within subject ANOVA (α=0.05). This was done within subgroups: obese males, obese females, non-obese males and non-obese females.

RESULTS

Durnin and Womersly and Jackson and Pollock had reasonably good agreement with DXA in older Caucasian American females and males, respectively. The remaining equations significantly overestimated %BF in older Caucasian American males. Mixed results were found in females with Gause-Nilsson and Jackson and Pollock significantly underestimating %BF, while Visser and Kwok overestimated %BF.

CONCLUSION

Numerous factors of a population including age, race, ethnicity, gender and obesity should be considered when selecting a skinfold regression equation to estimate %BF. While Durnin and Womersly and Jackson and Pollock are recommended for predicting %BF in older Caucasian American females and males, respectively, there exists a need to develop accurate regression models that consider obesity, gender, race or ethnicity when predicting %BF in a diverse geriatric American population.

Use of fat mass and fat free mass standard deviation scores obtained using simple measurement methods in healthy children and patients: comparison with the reference 4-component model

Background

Clinical application of body composition (BC) measurements for individual children has been limited by lack of appropriate reference data.

Objectives

(1) To compare fat mass (FM) and fat free mass (FFM) standard deviation scores (SDS) generated using new body composition reference data and obtained using simple measurement methods in healthy children and patients with those obtained using the reference 4-component (4-C) model; (2) To determine the extent to which scores from simple methods agree with those from the 4-C model in identification of abnormal body composition.

Design

FM SDS were calculated for 4-C model, dual-energy X-ray absorptiometry (DXA; GE Lunar Prodigy), BMI and skinfold thicknesses (SFT); and FFM SDS for 4CM, DXA and bioelectrical impedance analysis (BIA; height²/Z)) in 927 subjects aged 3.8–22.0 y (211 healthy, 716 patients).

Results

DXA was the most accurate method for both FM and FFM SDS in healthy subjects and patients (mean bias (limits of agreement) FM SDS 0.03 (±0.62); FFM SDS −0.04 (±0.72)), and provided best agreement with the 4-C model in identifying abnormal BC (SDS ≤−2 or ≥2). BMI and SFTs were reasonable predictors of abnormal FM SDS, but poor in providing an absolute value. BIA was comparable to DXA for FFM SDS and in identifying abnormal subjects.

Conclusions

DXA may be used both for research and clinically to determine FM and FFM SDS. BIA may be used to assess FFM SDS in place of DXA. BMI and SFTs can be used to measure adiposity for groups but not individuals. The performance of simpler techniques in monitoring longitudinal BC changes requires investigation. Ultimately, the most appropriate method should be determined by its predictive value for clinical outcome.

Comparison of DEXA-derived body fat measurement to two race-specific bioelectrical impedance equations in healthy Indians

AIM

Prevalence of obesity is increasing in Asian Indians. Reliable, precise and convenient methods to estimate body composition are required. This study aimed to test the accuracy of bioelectrical impedance analysis (BIA) estimates of body composition among Asian Indians according to two BIA equations--one developed for Asians, the other for Caucasians.

METHODS

Two hundred apparently healthy Asian Indians (100 males, 100 females; mean age 36.6 ± 7.6 years; mean BMI 16.6-46.7 kg/m(2)) underwent BIA assessment of fat mass (FM), fat free mass (FFM) and percentage body fat (%BF) using Tanita Multi-Frequency Body Composition Analyzer MC-180MA (Tanita Corporation, Tokyo, Japan). One set of BIA values was automatically calculated by the analyzer (Caucasian figures), the other set by Tanita (Japanese Asian figures). Results were compared to dual X-ray absorptiometry (DEXA) as the standard measure.

RESULTS

A moderate level of relative agreement was found between the DEXA-derived measurement of %BF and the estimate from both the Caucasian (r(2)=0.75; p<0.001) and Asian equation (r(2)=0.7; p<0.001). Despite this, the level of absolute agreement was poor, with large bias and wide limits of agreement. According to the Caucasian equation the mean difference between methods was -8.3 ± 3.9 (95% limits of agreement -20.10 to 9.40), for the Asian equations mean difference was -5.4 ± 4.3 (95% limits of agreement -20.63 to 11.41).

INTERPRETATION AND CONCLUSIONS

When compared to DEXA, the current Asian and Caucasian Tanita formulae significantly under-estimate the %BF of Asian Indians.

Improved Prediction of Body Fat by Measuring Skinfold Thickness, Circumferences, and Bone Breadths

OBJECTIVE

To develop improved predictive regression equations for body fat content derived from common anthropometric measurements.

RESEARCH METHODS AND PROCEDURES

117 healthy German subjects, 46 men and 71 women, 26 to 67 years of age, from two different studies were assigned to a validation and a cross-validation group. Common anthropometric measurements and body composition by DXA were obtained. Equations using anthropometric measurements predicting body fat mass (BFM) with DXA as a reference method were developed using regression models.

RESULTS

The final best predictive sex-specific equations combining skinfold thicknesses (SF), circumferences, and bone breadth measurements were as follows: BFM(New) (kg) for men = -40.750 + {(0.397 x waist circumference) + [6.568 x (log triceps SF + log subscapular SF + log abdominal SF)]} and BFM(New) (kg) for women = -75.231 + {(0.512 x hip circumference) + [8.889 x (log chin SF + log triceps SF + log subscapular SF)] + (1.905 x knee breadth)}. The estimates of BFM from both validation and cross-validation had an excellent correlation, showed excellent correspondence to the DXA estimates, and showed a negligible tendency to underestimate percent body fat in subjects with higher BFM compared with equations using a two-compartment (Durnin and Womersley) or a four-compartment (Peterson) model as the reference method.

DISCUSSION

Combining skinfold thicknesses with circumference and/or bone breadth measures provide a more precise prediction of percent body fat in comparison with established SF equations. Our equations are recommended for use in clinical or epidemiological settings in populations with similar ethnic background.

Generalised equations for the prediction of percentage body fat by anthropometry in adult men and women aged 18-81 years

Anthropometric data indicate that the human phenotype is changing. Today's adult is greater in stature, body mass and fat mass. Accurate measurement of body composition is necessary to maintain surveillance of obesity within the population and to evaluate associated interventions. The aim of the present study was to construct and validate generalised equations for percentage body fat (%BF) prediction from anthropometry in 1136 adult men and women. Reference values for %BF were obtained using dual-energy X-ray absorptiometry. Skinfold thickness (SF) at ten sites and girth (G) at seven sites were measured on 736 men and women aged 18-81 years (%BF 5·1-56·8%). Quantile regression was employed to construct prediction equations from age and log-transformed SF and G measures. These equations were then cross-validated on a cohort of 400 subjects of similar age and fatness. The following generalised equations were found to most accurately predict %BF: Men: (age x 0·1) + (logtricepsSF x 7·6) + (logmidaxillaSF x 8·8) + (logsuprspinaleSF x 11·9) - 11·3 (standard error of the estimate: 2·5%, 95% limits of agreement: - 4·8, + 4·9) Women: (age x 0·1) + (logabdominalG x 39·4) + (logmidaxillaSF x 4·9) + (logbicepsSF x 11·0) + (logmedialcalfSF x 9·1) - 73·5 (standard error of the estimate: 3·0%, 95% limits of agreement: - 5·7, + 5·9) These generalised anthropometric equations accurately predict %BF and are suitable for the measurement of %BF in adult men and women of varying levels of fatness across the lifespan.

Concordance of the recently published body adiposity index with measured body fat percent in European-American adults

The body adiposity index (BAI; hip circumference (cm)/height (m)(1.5) - 18) has recently been shown to demonstrate a stronger correlation with percentage body fat (%fat) than that between the BMI and %fat in Mexican-American adults. Here, we compare the concordance between %fat from dual-energy X-ray absorptiometry (DXA) and BAI, and between %fat and BMI, in European-American adults (n = 623). Agreement between BAI, BMI, and %fat was assessed using Lin's concordance coefficients (ρ(c)), where values <0.90 are considered poor. In the sample as a whole, the agreement between BAI and %fat (ρ(c) = 0.752) was far better than that between BMI and %fat (ρ(c) = 0.445) but was nonetheless relatively poor. There were large mean differences in %fat between the BAI and DXA %fat, particularly at lower levels of adiposity (<20%), and further the BAI overestimated %fat in males and underestimated %fat in females. Optimizing the BAI formula for our sample only marginally improved performance. Results of the present study show that BAI provides a better indicator of adiposity in European-American adults than does BMI, but does not provide valid estimates of %fat, particularly at lower levels of body fatness. Further research is warranted to investigate the predictive ability of BAI for various health outcomes.

Increase in android fat mass with age in healthy women with normal body mass index

Body fat distribution is gender specific: men tend to accumulate adipose tissue in the android region, whereas women tend to do so in the gynoid region. The aim of the study was to assess total fat mass (TFM), android fat (AF), and gynoid fat (GF) mass in a selected group of healthy adult women with normal body mass index (BMI) to evaluate variations in fat distribution. Seventy-seven women (20--69yr of age) with BMI values between ≥18.5 and ≤24.9kg/m(2) were included. TMF, AF, GF, and the AF to GF ratio (A:G) were assessed using dual-energy X-ray absorptiometry. Results showed an increase in AF after the fifth decade of life (D), which reached statistical significance in the sixth and seventh decades (p<0.05--0.008), a 33% increase in kg of AF between the fourth and seventh and a 20% increase in A:G between the third and the seventh, with no significant changes in TFM and GF. In normal BMI women, age appears to be associated with changes in fat mass distribution with an increase in AF, which might have potential deleterious health consequences, after the fifth D.

Promoter methylation of serotonin transporter gene is associated with obesity measures: a monozygotic twin study

Objective:

Epigenetic mechanisms are increasingly being recognized as an important factor for obesity. The serotonin transporter gene (SLC6A4) has a critical role in regulating food intake, body weight and energy balance. This study examines the potential association between SLC6A4 promoter methylation and obesity measures in a monozygotic (MZ) twin sample.

Methods:

We studied 84 MZ twin pairs drawn from the Vietnam Era Twin Registry. Obesity measures include body mass index (BMI), body weight, waist circumference (WC) and waist-hip ratio (WHR). The SLC6A4 promoter methylation profile in peripheral blood leukocytes was quantified by bisulfite pyrosequencing. The association between methylation variation and obesity parameters was examined by mixed-model regression and matched pair analysis, adjusting for age, smoking, alcohol consumption, physical activity and total daily energy intake. Multiple testing was controlled using the adjusted false discovery rate (q-value).

Results:

Mean methylation level was positively correlated with BMI (r=0.29; P=0.0002), body weight (r=0.31; P<0.0001) and WC (r=0.20; P=0.009), but not WHR. Intra-pair differences in mean methylation were significantly correlated with intra-pair differences in BMI, body weight and WC, but not WHR. On average, a 1% increase in mean methylation was associated with 0.33 kg m⁻² increase in BMI (95% CI: 0.02–0.65; P=0.03), 1.16 kg increase in body weight (95% CI, 0.16–2.16; P=0.02) and 0.78 cm increase in WC (95% CI, 0.05–1.50; P=0.03) after controlling for potential confounders.

Conclusions:

SLC6A4 promoter hypermethylation is significantly associated with an increased prevalence of obesity within a MZ twin study.

Fat-free mass predictions through a Bayesian Network enable body composition comparisons in various populations

The respective contribution of fat-free mass (FFM) and fat mass to body weight (Wgt) is a relevant indicator of risk for major public health issues. In an earlier study, a Bayesian Network (BN) was designed to predict FFM from a DXA database (1999-2004 NHANES, n = 10,402) with easily accessible variables [sex, age, Wgt, and height (Hgt)]. The objective of the present study was to assess the robustness of these BN predictions in different population contexts (age, BMI, ethnicity, etc.) when covariables were stochastically deduced from population-based distributions. BN covariables were adjusted to 82 published distributions for age, Wgt, and Hgt from 16 studies assessing body composition. Anthropometric adjustments required a surrogate database (n = 23,411) to get the missing correlation between published Wgt and Hgt distributions. Published BMI distributions and their predicted BN counterparts were correlated (R(2) = 0.99; P < 0.001). Predicted FFM distributions were closely adjusted to their published counterparts for both sexes between 20 and 79 y old, with some discrepancies for Asian populations. In addition, BN predictions revealed a very good agreement between FFM assessed in different population contexts. The mean difference between published FFM values (61.1 ± 3.44 and 42.7 ± 3.32 kg for men and women, respectively) and BN predictions (61.6 ± 3.11 and 42.4 ± 2.76 kg for men and women, respectively) was <1% when FFM was assessed by DXA; the difference rose to 3.6% when FFM was assessed by bioelectric impedance analysis or by densitometry methods. These results suggest that it is possible, within certain anthropometric limitations, to use BN predictions as a complementary body composition analysis for large populations.

Detailed analysis of variants in FTO in association with body composition in a cohort of 70-year-olds suggests a weakened effect among elderly

Background

The rs9939609 single-nucleotide polymorphism (SNP) in the fat mass and obesity (FTO) gene has previously been associated with higher BMI levels in children and young adults. In contrast, this association was not found in elderly men. BMI is a measure of overweight in relation to the individuals' height, but offers no insight into the regional body fat composition or distribution.

Objective

To examine whether the FTO gene is associated with overweight and body composition-related phenotypes rather than BMI, we measured waist circumference, total fat mass, trunk fat mass, leg fat mass, visceral and subcutaneous adipose tissue, and daily energy intake in 985 humans (493 women) at the age of 70 years. In total, 733 SNPs located in the FTO gene were genotyped in order to examine whether rs9939609 alone or the other SNPs, or their combinations, are linked to obesity-related measures in elderly humans.

Design

Cross-sectional analysis of the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) cohort.

Results

Neither a single SNP, such as rs9939609, nor a SNP combination was significantly linked to overweight, body composition-related measures, or daily energy intake in elderly humans. Of note, these observations hold both among men and women.

Conclusions

Due to the diversity of measurements included in the study, our findings strengthen the view that the effect of FTO on body composition appears to be less profound in later life compared to younger ages and that this is seemingly independent of gender.

Body composition predicted with a Bayesian network from simple variables

The relative contributions of fat-free mass (FFM) and fat mass (FM) to body weight are key indicators for several major public health issues. Predictive models could offer new insights into body composition analysis. A non-parametric equation derived from a probabilistic Bayesian network (BN) was established by including sex, age, body weight and height. We hypothesised that it would be possible to assess the body composition of any subject from easily accessible covariables by selecting an adjusted FFM value within a reference dual-energy X-ray absorptiometry (DXA) measurement database (1999-2004 National Health and Nutrition Examination Survey (NHANES), n 10 402). FM was directly calculated as body weight minus FFM. A French DXA database (n 1140) was used (1) to adjust the model parameters (n 380) and (2) to cross-validate the model responses (n 760). French subjects were significantly different from American NHANES subjects with respect to age, weight and FM. Despite this different population context, BN prediction was highly reliable. Correlations between BN predictions and DXA measurements were significant for FFM (R2 0·94, P < 0·001, standard error of prediction (SEP) 2·82 kg) and the percentage of FM (FM%) (R2 0·81, P < 0·001, SEP 3·73 %). Two previously published linear models were applied to the subjects of the French database and compared with BN predictions. BN predictions were more accurate for both FFM and FM than those obtained from linear models. In addition, BN prediction generated stochastic variability in the FM% expressed in terms of BMI. The use of such predictions in large populations could be of interest for many public health issues.

Measurement of longitudinal changes in body composition during weight loss and maintenance in overweight and obese subjects using air-displacement plethysmography in comparison with the deuterium dilution technique

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 (R(2)=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.

Lower-limb and whole-body tissue composition assessment in healthy active older women

AIM

The study evaluated, in active elderly women, the accuracy and bias of anthropometry and bioelectrical impedance analysis (BIA) for lower-limb and whole-body tissue composition measures using dual-energy X-ray absorptiometry (DXA) as the criterion method.

METHODS

Nineteen individuals (66.1 +/- 4.2 years) participated in the study. Whole-body fat mass (FM) and fat-free mass (FFM) were measured by anthropometry, BIA and DXA. Lower-limb volume (LLV) and lower-limb FFM (LLFFM) were assessed by anthropometry and DXA.

RESULTS

LLV and LLFFM were significantly overestimated by anthropometry vs. DXA (p < 0.05 and p < 0.001, respectively) but significant relationships were observed [coefficient of determination (R(2)) > 0.25, p < 0.05]. No significant difference was observed between FM(A) (where (A) stands for anthropometry) vs. FM(DXA) and FFM(A) vs. FFM(DXA) and significant relationships were observed [R(2) = 0.93, p < 0.001, coefficient of variation (CV) = 7.3%; and R(2) = 0.85, p < 0.001, CV = 4.4%, respectively]. No significant difference was observed between FM(BIA) and FM(DXA) and a significant relationship was observed (R(2) = 0.80, p < 0.001, CV = 11.6%). FFM was significantly underestimated by BIA vs. DXA (p < 0.01).

CONCLUSIONS

In active elderly women, (i) compared with DXA, anthropometry overestimates LLV and LLFFM; (ii) anthropometry can be an accurate method for assessing whole-body composition; and (iii) despite a non-significant bias for the FM measurement, the BIA tends to overestimate FM and underestimate FFM.

Energy intake and expenditure during a 6-day cycling stage race

Energy intake (EI) and energy expenditure (EE) are relatively easy to measure accurately over short periods in a laboratory setting, but less so during a multi-day competition. Our goal was to measure EI and EE as accurately as possible during a 6-day, 10-stage cycling race. We prepared all meals and supplements, assessed EI (weighed diet-records) and macrontrient intake, total EE (doubly labelled water), resting metabolic rate (respiratory gas exchange), exercise EE (power meters), and body mass. Body composition was measured several days before and after racing (dual x-ray absorptiometry). Body mass remained stable over the course of the race. The mean EI (27.3+/-3.8 MJ/day) nearly matched EE (27.4+/-2.0 MJ/day). The majority (62%) of EE was exercise EE. Macronutrient intake was within or exceeded the recommendations. Lean body mass increased and fat mass decreased in most of our participants. Our study indicates that EI can match high EE with adequate macronutrient intake during multi-day cycle racing and may be facilitated by appropriate foods being available at appropriate times. This optimization of nutritional provision supports positive changes in body composition.

Cross-validation of generalised body composition equations with diverse young men and women: the Training Intervention and Genetics of Exercise Response (TIGER) Study

Generalised skinfold equations developed in the 1970s are commonly used to estimate laboratory-measured percentage fat (BF%). The equations were developed on predominately white individuals using Siri's two-component percentage fat equation (BF%-GEN). We cross-validated the Jackson-Pollock (JP) generalised equations with samples of young white, Hispanic and African-American men and women using dual-energy X-ray absorptiometry (DXA) as the BF% referent criterion (BF%-DXA). The cross-sectional sample included 1129 women and men (aged 17-35 years). The correlations between BF%-GEN and BF%-DXA were 0.85 for women and 0.93 for men. Analysis of measurement error showed that BF%-GEN underestimated BF%-DXA of men and women by 1.3 and 3.0 %. General linear models (GLM) confirmed that BF%-GEN systematically underestimated BF%-DXA of Hispanic men and women, and overestimated BF%-DXA of African-American men. GLM were used to estimate BF%-DXA from the JP sum of skinfolds and to account for race/ethnic group bias. The fit statistics (R and standard error of the estimate; see) of the men's calibration model were: white, R 0.92, see 3.0 %; Hispanic, R 0.91, see 3.0 %; African-American, R 0.95, see 2.6 %. The women's statistics were: white and African-American, R 0.86, see 3.8 %; Hispanic, R 0.83, see 3.4 %. These results showed that BF%-GEN and BF%-DXA were highly correlated, but the error analyses documented that the generalised equations lacked accuracy when applied to these racially and ethnically diverse men and women. The inaccuracy was linked to the body composition and race/ethnic differences between these Training Intervention and Genetics of Exercise Response (TIGER) study subjects and the men and women used to develop the generalised equations in the 1970s and using BF%-DXA as the referent criterion.

Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial

BACKGROUND

Growth hormone secretion and muscle mass decline from midpuberty throughout life, culminating in sarcopenia, frailty, decreased function, and loss of independence. The decline of growth hormone in the development of sarcopenia is one of many factors, and its etiologic role needs to be demonstrated.

OBJECTIVE

To determine whether MK-677, an oral ghrelin mimetic, increases growth hormone secretion into the young-adult range without serious adverse effects, prevents the decline of fat-free mass, and decreases abdominal visceral fat in healthy older adults.

DESIGN

2-year, double-blind, randomized, placebo-controlled, modified-crossover clinical trial.

SETTING

General clinical research center study performed at a university hospital.

PARTICIPANTS

65 healthy adults (men, women receiving hormone replacement therapy, and women not receiving hormone replacement therapy) ranging from 60 to 81 years of age.

INTERVENTION

Oral administration of MK-677, 25 mg, or placebo once daily.

MEASUREMENTS

Growth hormone and insulin-like growth factor I levels. Fat-free mass and abdominal visceral fat were the primary end points after 1 year of treatment. Other end points were body weight, fat mass, insulin sensitivity, lipid and cortisol levels, bone mineral density, limb lean and fat mass, isokinetic strength, function, and quality of life. All end points were assessed at baseline and every 6 months.

RESULTS

Daily administration of MK-677 significantly increased growth hormone and insulin-like growth factor I levels to those of healthy young adults without serious adverse effects. Mean fat-free mass decreased in the placebo group but increased in the MK-677 group (change, -0.5 kg [95% CI, -1.1 to 0.2 kg] vs. 1.1 kg [CI, 0.7 to 1.5 kg], respectively; P < 0.001), as did body cell mass, as reflected by intracellular water (change, -1.0 kg [CI, -2.1 to 0.2 kg] vs. 0.8 kg [CI, -0.1 to 1.6 kg], respectively; P = 0.021). No significant differences were observed in abdominal visceral fat or total fat mass; however, the average increase in limb fat was greater in the MK-677 group than the placebo group (1.1 kg vs. 0.24 kg; P = 0.001). Body weight increased 0.8 kg (CI, -0.3 to 1.8 kg) in the placebo group and 2.7 kg (CI, 2.0 to 3.5 kg) in the MK-677 group (P = 0.003). Fasting blood glucose level increased an average of 0.3 mmol/L (5 mg/dL) in the MK-677 group (P = 0.015), and insulin sensitivity decreased. The most frequent side effects were an increase in appetite that subsided in a few months and transient, mild lower-extremity edema and muscle pain. Low-density lipoprotein cholesterol levels decreased in the MK-677 group relative to baseline values (change, -0.14 mmol/L [CI, -0.27 to -0.01 mmol/L]; -5.4 mg/dL [CI, -10.4 to -0.4 mg/dL]; P = 0.026); no differences between groups were observed in total or high-density lipoprotein cholesterol levels. Cortisol levels increased 47 nmol/L (CI, 28 to 71 nmol/L (1.7 microg/dL [CI, 1.0 to 2.6 microg/dL]) in MK-677 recipients (P = 0.020). Changes in bone mineral density consistent with increased bone remodeling occurred in MK-677 recipients. Increased fat-free mass did not result in changes in strength or function. Two-year exploratory analyses confirmed the 1-year results.

LIMITATION

Study power (duration and participant number) was insufficient to evaluate functional end points in healthy elderly persons.

CONCLUSION

Over 12 months, the ghrelin mimetic MK-677 enhanced pulsatile growth hormone secretion, significantly increased fat-free mass, and was generally well tolerated. Long-term functional and, ultimately, pharmacoeconomic, studies in elderly persons are indicated.

Percent body fat estimations in college men using field and laboratory methods: a three-compartment model approach

BACKGROUND

Methods used to estimate percent body fat can be classified as a laboratory or field technique. However, the validity of these methods compared to multiple-compartment models has not been fully established. The purpose of this study was to determine the validity of field and laboratory methods for estimating percent fat (%fat) in healthy college-age men compared to the Siri three-compartment model (3C).

METHODS

Thirty-one Caucasian men (22.5 +/- 2.7 yrs; 175.6 +/- 6.3 cm; 76.4 +/- 10.3 kg) had their %fat estimated by bioelectrical impedance analysis (BIA) using the BodyGram computer program (BIA-AK) and population-specific equation (BIA-Lohman), near-infrared interactance (NIR) (Futrex(R) 6100/XL), four circumference-based military equations [Marine Corps (MC), Navy and Air Force (NAF), Army (A), and Friedl], air-displacement plethysmography (BP), and hydrostatic weighing (HW).

RESULTS

All circumference-based military equations (MC = 4.7% fat, NAF = 5.2% fat, A = 4.7% fat, Friedl = 4.7% fat) along with NIR (NIR = 5.1% fat) produced an unacceptable total error (TE). Both laboratory methods produced acceptable TE values (HW = 2.5% fat; BP = 2.7% fat). The BIA-AK, and BIA-Lohman field methods produced acceptable TE values (2.1% fat). A significant difference was observed for the MC and NAF equations compared to both the 3C model and HW (p < 0.006).

CONCLUSION

Results indicate that the BP and HW are valid laboratory methods when compared to the 3C model to estimate %fat in college-age Caucasian men. When the use of a laboratory method is not feasible, BIA-AK, and BIA-Lohman are acceptable field methods to estimate %fat in this population.

Percent body fat estimations in college women using field and laboratory methods: a three-compartment model approach

BACKGROUND

Methods used to estimate percent body fat can be classified as a laboratory or field technique. However, the validity of these methods compared to multiple-compartment models has not been fully established. This investigation sought to determine the validity of field and laboratory methods for estimating percent fat (%fat) in healthy college-age women compared to the Siri three-compartment model (3C).

METHODS

Thirty Caucasian women (21.1 +/- 1.5 yrs; 164.8 +/- 4.7 cm; 61.2 +/- 6.8 kg) had their %fat estimated by BIA using the BodyGramtrade mark computer program (BIA-AK) and population-specific equation (BIA-Lohman), NIR (Futrex(R) 6100/XL), a quadratic (SF3JPW) and linear (SF3WB) skinfold equation, air-displacement plethysmography (BP), and hydrostatic weighing (HW).

RESULTS

All methods produced acceptable total error (TE) values compared to the 3C model. Both laboratory methods produced similar TE values (HW, TE = 2.4%fat; BP, TE = 2.3%fat) when compared to the 3C model, though a significant constant error (CE) was detected for HW (1.5%fat, p 2.7%fat) compared to the 3C model. Additionally, the SF3JPW %fat estimation equation resulted in a significant CE (2.6%fat, p

CONCLUSION

Data suggest that the BP and HW are valid laboratory methods when compared to the 3C model to estimate %fat in college-age Caucasian women. When the use of a laboratory method is not feasible, NIR, BIA-AK, BIA-Lohman, SF3JPW, and SF3WB are acceptable field methods to estimate %fat in this population.

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Affiliation(s)

Jordan R Moon Department of Health and Exercise Science, University of Oklahoma, Norman, USA
Holly R Hull Department of Health and Exercise Science, University of Oklahoma, Norman, USA Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, USA
Sarah E Tobkin Department of Health and Exercise Science, University of Oklahoma, Norman, USA
Masaru Teramoto Department of Health and Exercise Science, University of Oklahoma, Norman, USA
Murat Karabulut Department of Health and Exercise Science, University of Oklahoma, Norman, USA
Michael D Roberts Department of Health and Exercise Science, University of Oklahoma, Norman, USA
Eric D Ryan Department of Health and Exercise Science, University of Oklahoma, Norman, USA
So Jung Kim Department of Health and Exercise Science, University of Oklahoma, Norman, USA
Vincent J Dalbo Department of Health and Exercise Science, University of Oklahoma, Norman, USA
Ashley A Walter Department of Health and Exercise Science, University of Oklahoma, Norman, USA
Abbie T Smith Department of Health and Exercise Science, University of Oklahoma, Norman, USA
Joel T Cramer Department of Health and Exercise Science, University of Oklahoma, Norman, USA
Jeffrey R Stout Department of Health and Exercise Science, University of Oklahoma, Norman, USA

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Link between Epilepsy and Malnutrition in a Rural Area of Benin

PURPOSE

Epilepsy and malnutrition are both important public health problems in sub-Saharan Africa. A relationship between epilepsy and malnutrition has been suspected for many years. Our objective was to investigate the association between epilepsy and malnutrition in Djidja, Benin.

METHODS

A matched population-based cross-sectional case-control survey was performed: cases (patients with epilepsy) were matched to controls according to sex, age +/- 5 years, and village of residence. The World Health Organization's criteria for malnutrition was used. Anthropometric measurements (weight, height, mid arm upper circumference, triceps skinfold thickness) were taken. Bioelectrical impedance analysis, a standardized food and social questionnaire and a clinical examination were done. Statistical analysis (conditional logistic regression) was performed using SAS 8.0.

RESULTS

A total of 131 cases and 262 controls were included. The prevalence of malnutrition was higher in cases than in controls (22.1% vs. 9.2%, p = 0.0006). Social factors were significantly different between cases and controls. Feeding difficulties were more frequent and health status was worse in cases. Seven variables were associated with epilepsy: (i) nutritional factors: mid arm upper circumference (prevalence odds ratio (pOR) = 0.7, CI: 0.6-0.9), cereal consumption <3 times during the 3 days before the study (pOR = 4.2, CI: 1.8-10.0), <3 meals/day (pOR = 4.2, CI: 1.6-10.9), tooth decay (pOR = 2.9, CI: 1.1-7.4), food taboos (pOR = 25.0, CI: 8.3-100.0), (ii) social factors: surrogate respondent (pOR = 16.8, CI: 3.1-90.3) and no second job (pOR = 7.1, CI: 2.3-22.3).

CONCLUSION

Epilepsy and nutritional status are linked in sub-Saharan Africa. Programs to improve the nutritional status of people with epilepsy are needed.

A pilot study of body composition and bone mineral density in healthy men from Argentina

A precise assessment of bone mineral density (BMD) and body composition can be performed using dual-energy X-ray absorptiometry (DXA). Values of body composition for males would be useful to evaluate the occurrence of alterations in body composition in a number of diseases. The objectives of this study were to establish BMD and body composition values in healthy men and to analyze age-related changes. BMD and body composition of total body and subareas were determined in 116 healthy men (aged 20-79 yr) using DXA. Comparison between 20-29- and 70-79-yr-old men showed that older subjects were shorter (p<0.03), and had a higher body mass index (p<0.01). Fat mass increased (+46.7%; p<0.001) especially in the trunk. Lean mass (LM) decreased (-9.4%; p<0.05) mainly in the arms and legs. Bone mineral content (BMC) and BMD decreased (-15.3% [p<0.001], -6.3% [p<0.05], respectively). Correlation was observed between BMC and LM (r=0.7, p<0.01). Values of BMD and body composition in healthy men were obtained. A relation was observed between bone mass and body composition, suggesting that the age-related decrease in LM may be associated to bone mass loss. Further studies should be conducted to elucidate the role of body composition in the occurrence of osteoporosis in men.

Comparison of different methods to assess body composition of weight loss in obese and diabetic patients

Estimating body composition is important to understand the metabolic and cardiovascular effects of adiposity. Estimating changes in body compartments arising from weight loss strategies is equally important to evaluate their benefits and risks, particularly in frail populations (elderly or diabetic), and following bariatric surgery. Body compartments were evaluated in 50 obese subjects (25 diabetic, 25 non-diabetic) before and after a 7 kg weight loss obtained after 6 months of calorie restriction and orlistat. Fat and fat-free mass (FFM) were estimated by bioelectrical impedance analysis (BIA), dual X-ray absorptiometry (DXA), plethysmography (BodPod) and a combination of these in a 3- or 4-compartment model, the latter being considered the reference method. FFM hydration was the ratio of total body water (BIA) to FFM. FFM hydration was significantly higher than classical values (75.9+/-3.0%, P<0.0001), and decreased with weight loss (74.2+/-3.3%). Compared to the 4-compartment, the 3-compartment model gave the most accurate fat and FFM estimation. A significant bias was observed with DXA, BodPod or BIA. Compartment changes induced by weight loss were accurately evaluated by DXA, being particularly precise in the 3-compartment analysis. No effect of diabetes per se was observed. A 3- or 4-compartmental analysis is necessary to accurately estimate body composition and its changes during weight loss.

Body composition by the four-compartment model: validity of the BOD POD for assessing body fat in mexican elderly

OBJECTIVE

The aims of this study were to validate BOD POD in a wide sample of healthy and independent Mexican elderly men and women subjects using the 4 compartment (4C) model as the reference method, and to evaluate the assumptions of the densitometric two-compartment (2C) model.

DESIGN

Cross-sectional study designed to assess body composition and validation of a method based on 2C model (BOD POD).

SETTING

Urban and rural regions of Sonora, Mexico.

SUBJECTS

Two hundred and two free-living subjects >or=60 years old were completed in this study.

METHODS

Body density and body fat were measured by the BOD POD, total body water by deuterium dilution and total body bone ash by dual energy X-ray absorptiometry. Body composition was determined using Baumgartner's equation.

RESULTS

Percent body fat by the 4C model was 31.2 and 42.5% in men and women, respectively (P<0.001). Group mean accuracy of body fat by BOD POD against that of the 4C model showed an effect of sex (P<0.001), but not the method (P=0.27). Results of individual accuracy showed no significant difference with the identity line and the slope was significantly different from zero or a slope similar to one. Precision assessed by model R (2) was high for all subjects and for men and women by separate. The standard error of the estimate was low for all and for men and women by separate. Bland and Altman analysis showed no significant bias.

CONCLUSION

The BOD POD technique is a valid and reliable method compared to the 4C model and it could be applied in subjects with similar physical and anthropometric characteristics to subjects of this study.