Body composition analysis by air displacement plethysmography in normal weight to extremely obese adults

Measurement of body composition in postpartum South African women living with and without HIV infection

Background

While several methodologies are available to measure adiposity, few have been validated in sub-Saharan African (SSA) and none in postpartum African women living with HIV (WLHIV). We compared bioelectrical impendence analysis (BIA) and air displacement plethysmography (ADP) against dual x-ray absorptiometry (DXA) in South African women and examined differences by HIV and body mass index (BMI) status.

Methods

Lin's concordance correlation coefficient (CCC) test was used to examine fat mass (FM), fat free mass (FFM), and total body fat percent (%BF) difference between BIA vs. DXA, and ADP vs. DXA in women living with HIV (n = 57) and without HIV (n = 25). The Bland Altman test was used to assess mean differences and the direction of bias.

Results

The median age was 31 years (IQR, 26-35) and months postpartum were 11 (IQR, 7-16), 44% of the women had obesity. Lin's CCC for BIA and ADP vs. DXA were both 0.80 for %BF and 0.97 for FM, and 0.86 and 0.80 for FFM, respectively. Mean differences (DXA-BIA and ADP estimates) were 0.22 ± 4.54% (p = 0.54) and 3.35 ± 3.27% (p < 0.01) for %BF, -0.82 ± 3.56 kg (p = 0.06) and 1.43 ± 2.68 kg (p = 0.01) for FM, -1.38 ± 3.61 kg (p = 0.01) and - 3.34 ± 2.37 kg (p < 0.01) for FFM, respectively. BIA overestimated %BF in WLHIV and underestimated it in women with obesity.

Conclusion

Body composition measurements using BIA and ADP correlated well with DXA, thereby providing alternative, safe tools for measuring postpartum FM and FFM in SSA women, including WLHIV.

Ethnic Specific body fat percent prediction equation as surrogate marker of obesity in Ethiopian adults

BACKGROUND

Application of advanced body composition measurement methods is not practical in developing countries context due to cost and unavailability of facilities. This study generated ethnic specific body fat percent prediction equation for Ethiopian adults using appropriate data.

METHODS

A cross-sectional study was carried ifrom February to April 2015 among 704 randomly selected adult employees of Jimma University. Ethnic specific Ethiopian body fat percent (BF%) prediction equation was developed using a multivariable linear regression model with measured BF% as dependent variable and age, sex, and body mass index as predictor variables. Agreement between fat percent measured using air displacement plethysmography and body fat percent estimated using Caucasian prediction equations was determined using Bland Altman plot.

RESULTS

Comparison of ADP measured and predicted BF% showed that Caucasian prediction equation underestimated body fat percent among Ethiopian adults by 6.78% (P < 0.0001). This finding is consistent across all age groups and ethnicities in both sexes. Bland Altman plot did not show agreement between ADP and Caucasian prediction equation (mean difference = 6.7825) and some of the points are outside 95% confidence interval. The caucasian prediction equation significantly underestimates body fat percent in Ethiopian adults, which is consistent across all ethnic groups in the sample. The study developed Ethnic specific BF% prediction equations for Ethiopian adults.

CONCLUSION

The Caucasian prediction equation significantly underestimates body fat percent among Ethiopian adults regardless of ethnicity. Ethiopian ethnic-specific prediction equation can be used as a very simple, cheap, and cost-effective alternative for estimating body fat percent among Ethiopian adults for health care provision in the prevention of obesity and related morbidities and for research purposes.

Development and validation of body fat percent prediction equation for screening obesity in adults

BACKGROUND

In Ethiopia, use of advanced body composition measurement methods may not be feasible due cost and unavailability of the facilities. This study developed and validated body fat percent prediction equation for adults using locally appropriate data.

METHODS

The study was conducted from February to April 2015 among 704 randomly selected adult employees of Jimma University. The total sample was spilt and randomly assigned to a training (n = 352) sample used for developing Ethiopian body fat percent (BF%) prediction equation and a testing (validation) sample (n = 352) used for determining the validity of the equation. A multivariable linear regression model was used to develop BF% prediction equation on the training sample using Air displacement Plethysmography (ADP) measured BF% as dependent variable and age, sex and body mass index as predictor variables. For the testing (validation) sample, BF% measured using ADP and the one predicted using the newly developed Ethiopian and Caucasian BF% prediction equations were compared using validity measures, Kappa statistics and agreement between the two measures was determined using Bland Altman plot.

RESULTS

A multivariable linear regression model run on the testing population showed that age, sex and BMI were significant predictors of ADP measured BF%. Accordingly, the BF% prediction equation of Ethiopian adults was generated as follows: BF% = -8.601 + BMI (1.521) + Age (0.243) + Sex (-10.568), where sex = 1 for males and 0 for females. Comparison of measured and predicted BF% showed that there was no significant (P = 0.932) difference between ADP measured BF% and BF% predicted using Ethiopian equation with a mean (±SD) difference of 0.03 (±5.44). Conversely, there was a significant difference (<0.0001) between ADP measured BF% and the Caucasian Equation estimated BF% with a mean (±SD) of 6.83 (±5.57). In both males and females, the Ethiopian equation demonstrated a very good to excellent sensitivity, specificity, positive predictive value and negative predictive values. Conversely, the Caucasian equation had poor sensitivity and negative predictive values, while it demonstrated an excellent specificity and positive predictive value. Likewise, there was a substantial Kappa agreement for males (K = 0.741) and for females (K = 0.720) between Ethiopian equation and ADP in diagnosing obesity among males based on BF%, while there was a slight Kappa agreement for males (K = 0.156) and a fair Kappa agreement for females (K = 0.365) between Caucasian equation and ADP (P < 0.001). Bland Altman plot showed a good agreement between ADP measured BF% for the Ethiopian Equation and not for the Caucasian equation. It was observed that the Ethiopian equation has a better prediction of BF% when compared to the measured one, but the Caucasian equation consistently underestimated BF% for all samples with different levels BF%.

CONCLUSION

The new Ethiopian BF% prediction equation performed very well in predicting BF% in the testing population in terms of validity measures, Kappa agreement and Bland Altman plot; while the Caucasian equation significantly underestimated body fat percent among Ethiopian adults. The results imply that the new Ethiopian equation can be used as a cost effective and user friendly screening method for early detection of obesity for the prevention of associated morbidity and mortality in Ethiopian adults.

Animal Protein versus Plant Protein in Supporting Lean Mass and Muscle Strength: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Although animal protein is usually considered to be a more potent stimulator of muscle protein synthesis than plant protein, the effect of protein source on lean mass and muscle strength needs to be systematically reviewed. This study aimed to examine potential differences in the effect of animal vs. plant protein on lean mass and muscle strength, and the possible influence of resistance exercise training (RET) and age. The following databases were searched: PubMed, Embase, Scopus and CINAHL Plus with Full Text, and 3081 articles were screened. A total of 18 articles were selected for systematic review, of which, 16 were used for meta-analysis. Total protein intakes were generally above the recommended dietary allowance at the baseline and end of intervention. Results from the meta-analyses demonstrated that protein source did not affect changes in absolute lean mass or muscle strength. However, there was a favoring effect of animal protein on percent lean mass. RET had no influence on the results, while younger adults (<50 years) were found to gain absolute and percent lean mass with animal protein intake (weighted mean difference (WMD), 0.41 kg; 95% confidence interval (CI) 0.08 to 0.74; WMD 0.50%; 95% CI 0.00 to 1.01). Collectively, animal protein tends to be more beneficial for lean mass than plant protein, especially in younger adults.

Alterations in Adiponectin, Leptin, Resistin, Testosterone, and Cortisol across Eleven Weeks of Training among Division One Collegiate Throwers: A Preliminary Study

Cytokine and hormone concentrations can be linked to the manipulation of training variables and to subsequent alterations in performance.

SUBJECTS

Nine D-1 collegiate throwers and 4 control subjects participated in this preliminary and exploratory report.

METHODS

Hormone (testosterone (T) and cortisol (C)) and adipokine (adiponectin, leptin, and resistin) measurements were taken at weeks 1, 7, and 11 for the throwers and weeks 1 and 11 for the control group. The throwers participated in an 11-week periodized resistance training and throws program during the fall preparatory period. Volume load was recorded throughout the study.

RESULTS

Hormone values did not exhibit statistically significant changes across time; however, there were notable changes for C, the testosterone to cortisol ratio (T:C), and adiponectin.

CONCLUSIONS

T:C was increased as volume load decreased, and adiponectin increased in concert with decreases in C and increases in the T:C, possibly suggesting a lesser degree of obesity-related inflammation and a higher degree of "fitness" and preparedness.

Agreement Between 2 Segmental Bioimpedance Devices, BOD POD, and DXA in Obese Adults

This study examined the agreement between 2 segmental bioimpedance analysis (BIA) devices, air displacement plethysmography (BOD POD), and dual energy X-ray absorptiometry (DXA) for estimating body composition in obese adults. Fifty obese adults (25 men and 25 women; age = 34.20 ± 11.19 years; BMI = 36.14 ± 5.33 kg/m²) had their body fat percentage (BF%) and fat-free mass (FFM) evaluated with 2 segmental BIA devices (InBody 230 and InBody 720), BOD POD, and DXA (Lunar iDXA). Body composition via the BOD POD was determined using the Siri equation whereas manufacturer-based equations generated metrics (ie, BF% and FFM) for the InBody devices. The effect size of the mean differences for all BF% and FFM comparisons were trivial (Cohen's d < 0.20). The standard error of estimate (SEE), total error (TE), and 95% limits of agreement (LOAs) were low for both segmental BIA devices when compared to DXA (SEE < 2.26% and 2.35 kg; TE < 2.58% and 2.66 kg; 95% LOAs < ± 4.94% and 4.86kg). The error for BOD POD was also low when compared to DXA (SEE = 2.39% and 2.57 kg; TE = 2.34% and 2.56 kg; 95% LOAs = 4.63% and 5.06 kg). Validity statistics were slightly higher, but considered acceptable, when comparing the segmental BIA devices against BOD POD (SEE < 3.37% and 3.63 kg; TE < 3.44% and 3.79 kg; 95% LOAs < ± 6.62% and 7.19 kg). Lastly, the 2 segmental BIA devices produced nearly identical validity statistics when compared to each other. However, both BIA devices revealed proportional bias for BF% and FFM when compared to the BOD POD and DXA (all p < 0.05). The current study's findings indicate the InBody 230 is interchangeable with the InBody 720 in obese adults. Also, the trivial effect size, when compared against the BOD POD and DXA, suggest the InBody devices could be used for estimating group BF% and FFM. In contrast, the significant proportional bias demonstrates the BIA devices are not acceptable for individual estimates of body composition in an obese clinical population.

Assessing the Validity of Bioelectrical Impedance and Skinfold Calipers for Measuring Body Composition in NOLS Backcountry Hikers

INTRODUCTION

The National Outdoor Leadership School (NOLS) conducts backcountry research in an effort to provide the most up-to-date support to its students. Past research efforts have used a variety of body composition measurement tools, including bioelectrical impedance (BIA), skinfold calipers, and air displacement plethysmography (Bod Pod), but these tools are not interchangeable. The purpose of this study was to determine the feasibility and accuracy of the Tanita scale and the Harpenden skinfold calipers for assessing body composition in backcountry hikers.

METHODS

Twenty-two NOLS participants completed a 23-d backpacking trip into the Wind River Range in Wyoming. Pre- and postexpedition anthropometric measures were collected using 3 different body composition measurement tools: Tanita segmental body composition monitor, Harpenden skinfold calipers, and the Bod Pod. For the purposes of this study, the Bod Pod was used as the standard against which other methods were compared.

RESULTS

Participants lost a significant amount of weight and fat during the expedition. Fat-free mass increased by 0.4±1.9 kg, but this did not reach significance. A high degree of reliability was found between skinfold calipers and the Bod Pod and between BIA and the Bod Pod. The BIA measurements significantly underreported body fat percentage when compared to the Bod Pod, whereas the skinfold measurements were not significantly different from the Bod Pod, but measurements were more variable.

CONCLUSIONS

This study shows that the skinfold caliper and the Tanita scale give measurements comparable to the less readily available and more costly Bod Pod measurement in backcountry expedition participants.

A new anthropometric index for body fat estimation in patients with severe obesity

Background

Body mass index (BMI) has been used to assess body adiposity, but it cannot adequately reflect body fat (BF) amount. The body adiposity index (BAI) has been shown a better performance than BMI for this purpose, but it can be inaccurate to estimate BF under extreme amounts of fat. Here, we propose a new anthropometric index, the Belarmino–Waitzberg (BeW) index, for specific estimation of BF in severely obese patients.

Methods

In 144 adult patients with severe obesity, BF was estimated by air displacement plethysmography (ADP), as the reference method, along with the follow anthropometric measurements: height, abdominal circumference (AC), hip circumference (HC), weight, BMI (weight/ height²) and BAI ([HC(cm) / height (m)^1.5) − 18] × 100). Patients were proportionately distributed into two distinct databases, the building model database (BMD) and the validation model database (VMD), which were applied to develop and validate the BeW index, respectively. The BeW index was tested for gender and ethnicity adjustment as independent variables. The agreement of BF% values obtained by the new index and by BAI with ADP was also assessed.

Results

The BF% was 52.05 ± 5.42 for ADP and 59.11 ± 5.95 for the BeW index (all results are expressed as the mean ± standard deviation). A positive Pearson correlation (r = 0.74), a good accuracy (Cb = 0.94), and a positive Lin’s concordance correlation (CCC = 0.70) were observed between the two groups. The 95% limits of individual agreement between the BeW index and ADP were 6.8 to 7.9%, compared to − 7.5 to 14.8% between the BAI and ADP. The new index, called the Belarmino–Waitzberg (BeW) index, showed an improvement of 2.1% for the R² value and a significant gender effect, therefore resulting in two different indexes for females and males, as follows: Female BeW = − 48.8 + 0.087 × AC(cm) + 1.147 × HC(cm) - 0.003 × HC(cm)2 and Male BeW = − 48.8 + 0.087 × AC(cm) + 1.147 × HC(cm) - 0.003 × HC(cm)2–7.195.

Conclusions

The new BeW index showed a good performance for BF estimation in patients with severe obesity and can be superior to the BAI for this purpose.

Eating Behavior, Stress, and Adiposity: Discordance Between Perception and Physiology

The purpose of the study was to examine the interrelationships among stress, eating behavior, and adiposity in a cohort of normal- and overweight individuals. Clinical markers of physiological stress (fasting serum cortisol) and adiposity (body mass index [BMI] and percent body fat) were obtained from participants selected for a natural history protocol ( n = 107). Self-reported data on eating behavior (using the Three-Factor Eating Questionnaire subscales such as Cognitive Restraint, Disinhibition, and Hunger) and psychological stress (via the Perceived Stress Scale) were evaluated. Demographic information was incorporated using principal component analysis, which revealed sex- and weight-based differences in stress, adiposity, and eating behavior measures. Following a cross-sectional and descriptive analysis, significant correlations were found between the Disinhibition and Hunger eating behavior subscales and measures of adiposity including BMI ( r = .30, p = .002 and r = .20, p = .036, respectively) and percent body fat ( r = .43, p = .000 and r = .22, p = .022, respectively). Relationships between stress measures and eating behavior were also evident in the analysis. Disinhibition and Hunger correlated positively with perceived stress ( r = .32, p .001 and r = .26, p = .008, respectively). However, Disinhibition varied inversely with serum cortisol levels ( r = -.25, p = .009). Future studies are warranted to better understand this paradox underlying the effects of perceived and physiological stress on eating behavior.

Greater Strength Drives Difference in Power between Sexes in the Conventional Deadlift Exercise

Limited research exists comparing sex differences in muscular power. The primary purpose of this research was to determine if differences exist in power and velocity in the conventional deadlift (CDL). A secondary purpose was to examine the relationship among power, velocity, strength, and fat free mass (FFM). Eighteen strength trained athletes with ≥1 year CDL experience (women: n = 9, 29 ± 2 years, 162.3 ± 1.8 cm, 62 ± 2.4 kg, 23.3 ± 3.2 % body fat (%BF); men: n = 9, 29 ± 3 years, 175.6 ± 1.8 cm, 85.5 ± 1.4 kg, 14.8 ± 2.4 %BF), and ≥1.5 one repetition maximum (1-RM) CDL: body mass (BM) ratio (women: 1.6 ± 0.1 1-RM CDL: BM; men: 2.3 ± 0.1 1-RM CDL: BM), performed baseline (body composition, 1-RM CDL) and experimental sessions, in which velocity and power were measured at 30%, 60%, and 90% 1-RM. Repeated measures ANOVA and bivariate correlations were conducted. Men produced higher absolute average and peak power across all loads, but higher average velocity at only 30% 1-RM. When normalized to FFM, men produced higher peak and average power; however, women produced higher peak and average velocities across all loads. FFM and 1-RM were correlated with power. Greater power observed in men is driven by larger muscle mass, which contributes to greater strength.

Body adiposity index performance in estimating body fat in a sample of severely obese Brazilian patients

Background/objectives

The body adiposity index (BAI) estimates the amount of body fat (BF) in humans. In Mexican-American and African-American populations, BAI has performed better than body mass index (BMI). The aim of this study was to evaluate the performance of BAI in estimating percentage (BF%) in severely obese Brazilian patients, with air displacement plethysmography (ADP) used as the reference method.

Subjects/methods

Estimation of BF% by ADP, anthropometric measurements (height, abdominal and hip circumferences, body weight, and BMI) and BAI calculation were performed in 72 obese subjects (BMI ≥ 30 kg/m²) aged 30–55 years.

Results

The mean BF% estimates ± standard deviation were 52.1 ± 5.7 % for ADP and 47.7 ± 7.4 % for BAI, with a positive Pearson correlation (r_p = 0.66) and a positive Lin’s concordance correlation (r_c = 0.479) observed between these methods. The 95 % limits of individual agreement between BAI and ADP ranged from -5.769 % to 16.036 %, with BAI exhibiting an average positive bias of 5.13 % compared to the reference method. For each studied variable, BAI exhibited a systematic bias, as evidenced by a tendency for low BF% values to be overestimated.

Conclusion

For Brazilian patients with severe obesity, BAI does not provide an accurate estimate of BF%.

Air displacement plethysmography versus dual-energy x-ray absorptiometry in underweight, normal-weight, and overweight/obese individuals

BACKGROUND

Accurately estimating fat percentage is important for assessing health and determining treatment course. Methods of estimating body composition such as hydrostatic weighing or dual-energy x-ray absorptiometry (DXA), however, can be expensive, require extensive operator training, and, in the case of hydrostatic weighing, be highly burdensome for patients. Our objective was to evaluate air displacement plethysmography via the Bod Pod, a less burdensome method of estimating body fat percentage. In particular, we filled a gap in the literature by testing the Bod Pod at the lower extreme of the Body Mass Index (BMI) distribution.

FINDINGS

Three BMI groups were recruited and underwent both air displacement plethysmography and dual-energy x-ray absorptiometry. We recruited 30 healthy adults at the lower BMI distribution from the Calorie Restriction (CR) Society and followers of the CR Way. We also recruited 15 normal weight and 19 overweight/obese healthy adults from the general population. Both Siri and Brozek equations derived body fat percentage from the Bod Pod, and Bland-Altman analyses assessed agreement between the Bod Pod and DXA. Compared to DXA, the Bod Pod overestimated body fat percentage in thinner participants and underestimated body fat percentage in heavier participants, and the magnitude of difference was larger for underweight BMI participants, reaching 13% in some. The Bod Pod and DXA had smaller discrepancies in normal weight and overweight/obese participants.

CONCLUSIONS

While less burdensome, clinicians should be aware that Bod Pod estimates may deviate from DXA estimates particularly at the lower end of the BMI distribution.

Métodos de análise da composição corporal em adultos obesos

Os métodos de avaliação da composição corporal em obesos têm sido amplamente discutidos, uma vez que nesses indivíduos a avaliação é dificultada devido às limitações dos equipamentos e características dos métodos utilizados. Esta sessão temática tem o objetivo de esclarecer as características, vantagens e limitações dos métodos de avaliação da composição corporal em adultos obesos. A quantificação de gordura corporal e mas-sa livre de gordura, assim como a avaliação da perda de massa muscular e de massa óssea em obesos são temas de grande interesse científico, uma vez que são utilizados para diagnosticar a obesidade osteosarcopênica. A avaliação da composição corporal de obesos pelo modelo de múltiplos compartimentos é padrão-ouro na prática científica. Por outro lado, o método de absorciometria radiológica de feixe duplo é considerado o padrão de referência em pesquisas e na prática clínica. Estudos indicam que a ressonância magnética e a tomografia computadorizada, em alguns casos, são fortemente correlacionadas com a absorciometria radiológica de feixe duplo. Os demais métodos apresentam limitações em avaliar a composição corporal, bem como suas modificações durante a redução ponderal em indivíduos obesos.