Comparison of fat-free mass and body fat in Swiss and American adults

Is there a difference in the parameters of the bioelectrical impedance obtained from devices from different manufacturers? A cross-sectional study in hospitalized cancer patients

BACKGROUND

Cancer is a disease with high and increasing incidence rates in the world and its course tends to harm the body composition. Monitoring these body changes is very important. Therefore, it is essential to have reliable, accessible, and practical methods for evaluating body compartments. This study aims to evaluate the correlation and agreement of results for the bioelectrical impedance analysis (BIA) obtained from devices from different manufacturers.

METHODS

This is a single-center cross-sectional study including hospitalized patients with cancer. Two devices from different brands used for obtaining the BIA were used; both with a tetrapolar model and a single frequency (50 kHz). The results were evaluated for resistance (R) and reactance (Xc) and used to calculate the phase angle (PhA) and fat-free mass (FFM) indicators. Pearson and Spearman correlation tests and Bland-Altman plots were performed, with results expressed as bias and limits of agreement at 95% confidence intervals (95%CI).

RESULTS

We have included 116 patients, with a mean age of 60.8 ± 14.8, 51.7% were women. We have found very strong correlations between the measurements of R (rho = 0.971) and FFM (r = 0.979), and strong correlations for Xc (rho = 0.784) and PhA (rho = 0.768). However, the measurements did not agree between the methods.

CONCLUSIONS

Commercial brands of devices used for the BIA influence the results generated, a factor that must be considered when choosing the most appropriate method for this analysis.

Substantial but Misunderstood Human Sexual Dimorphism Results Mainly From Sexual Selection on Males and Natural Selection on Females

Human sexual dimorphism has been widely misunderstood. A large literature has underestimated the effect of differences in body composition and the role of male contest competition for mates. It is often assumed that sexually dimorphic traits reflect a history of sexual selection, but natural selection frequently builds different phenotypes in males and females. The relatively small sex difference in stature (∼7%) and its decrease during human evolution have been widely presumed to indicate decreased male contest competition for mates. However, females likely increased in stature relative to males in order to successfully deliver large-brained neonates through a bipedally-adapted pelvis. Despite the relatively small differences in stature and body mass (∼16%), there are marked sex differences in body composition. Across multiple samples from groups with different nutrition, males typically have 36% more lean body mass, 65% more muscle mass, and 72% more arm muscle than women, yielding parallel sex differences in strength. These sex differences in muscle and strength are comparable to those seen in primates where sexual selection, arising from aggressive male mating competition, has produced high levels of dimorphism. Body fat percentage shows a reverse pattern, with females having ∼1.6 times more than males and depositing that fat in different body regions than males. We argue that these sex differences in adipose arise mainly from natural selection on women to accumulate neurodevelopmental resources.

Physical performances show conflicting associations in aged manual workers

Ageing is associated with a decrease in physical performance implying that aged manual workers may be unable to match the physical requirements of their jobs. In this cross-sectional study, 96 male manual workers aged 51–72 years were recruited. Outcomes included handgrip strength (HGS), fat-free mass (FFM), fat percentage, cardiorespiratory fitness (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{{\rm{V}}}$$\end{document}V˙O₂max), forced vital capacity (FVC), forced expiratory volume after 1 s (FEV₁), spinal flexibility, sit-to-stand test performance and static balance. Covariates included height, smoking habits, leisure-time physical activity and systemic inflammation from blood samples. Outcomes were also compared with general populations. Age was negatively related to FFM and FEV₁, whereas static balance (velocity of displacement) was positively associated with age. Greater HGS, but poorer \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{{\rm{V}}}$$\end{document}V˙O₂max and FEV₁/FEV ratio were found compared with general populations. Age was negatively related with physical performances although a large part of the variance in performance could be explained by factors other than age such as smoking and systemic inflammation. The manual workers had greater muscle strength but had poorer cardiorespiratory fitness and lung function when compared with general populations. Specific health interventions targeting specifically cardiorespiratory fitness, lung function, and balance may be needed to maintain physical performances among manual workers.

Characteristics and reference values of fat mass index and fat free mass index by bioelectrical impedance analysis in an adult population

BACKGROUND & AIMS

We aim to examine the influence of sex, age, region and ethnicity on fat mass index (FMI) and fat free mass index (FFMI), and to establish FMI and FFMI reference values in Chinese adults.

METHODS

A stratified cluster sampling method was adopted to enroll Chinese participants in this cross-sectional study. Questionnaire surveys and medical examinations were performed to collect data, and body composition parameters were measured by bioelectrical impedance analysis. FMI and FFMI were calculated as the ratio of fat mass and fat free mass to the square of height. Differences in mean values for parameters were tested by Student's t-test or one-way analysis of variance. Reference values of FMI and FFMI were obtained using the percentiles method.

RESULTS

A total of 8959 multiethnic healthy Chinese adults were included in the analysis. Males had higher mean FFMI (males, 18.6 ± 1.6 kg/m²; females, 15.7 ± 1.1 kg/m², P < 0.001) but lower mean FMI (males, 5.1 ± 2.1 kg/m²; females, 7.8 ± 2.8 kg/m², P < 0.001) than did female participants regardless of age and ethnicity. For both sexes, FMI (Male: Bouyei, 4.2 ± 1.8 kg/m²; Uygur, 5.8 ± 2.2 kg/m², P < 0.001; Female: Bouyei, 6.7 ± 2.3 kg/m²; Uygur, 9.0 ± 3.2 kg/m², P < 0.001) and FFMI (Male: Bouyei, 17.8 ± 1.4 kg/m²; Uygur, 19.4 ± 1.6 kg/m², P < 0.001; Female: Bouyei, 15.1 ± 1.0 kg/m²; Uygur, 16.3 ± 1.1 kg/m², P < 0.001) were lowest in Bouyeis and highest in Uygurs. FMI and FFMI values increased with age until they peaked in the 30-39 year age group in males and after the age of 40 years in females for all ethnic groups. Reference values (5th-95th percentile) of FMI and FFMI were presented according to gender, age, region and ethnicity.

CONCLUSION

The body composition of Chinese population differs in different age, sex, ethnicity and region subgroups. Practitioners and future studies may need to consider different reference values for FMI and FFMI in Chinese adults among Han, Bouyei and Uygur populations; these values can serve as indices for evaluating nutrition status and identifying abnormalities in body composition.

Prevalence of low muscle mass according to body mass index in older adults

OBJECTIVE

Low muscle mass has been associated with increased morbi-mortality and should be identified for optimizing preventive and therapeutic strategies. This study evaluates the prevalence of bioelectrical impedance analysis (BIA)-derived low muscle mass in older persons using definitions found through a systematic literature search and determines the link between body mass index (BMI) and low muscle mass.

METHODS

We performed a systematic search of trials involving ≥100 persons that derived low muscle mass from BIA and reported cut-offs for low muscle mass normalized for body height or weight. These cut-offs were applied to all adults ≥65 y who underwent a BIA measurement at Geneva University Hospital between 1990 and 2011 (N = 3181). The association between BMI and low muscle mass was evaluated through multivariate logistic regressions.

RESULTS

We identified 15 cut-offs based on the fat-free mass index (FFMI), skeletal muscle index (SMI), or skeletal muscle percentage (SMP). Depending on the definition, the prevalence of low muscle mass was 17% to 68% in women and 17% to 85% in men. The risk of low muscle mass increased with a BMI <18.5 kg/m² when using cut-offs based on FFMI (odds ratio [OR] ♀ 14.28-24.04/♂ 25.42-50.64) or SMI (OR ♀ 3.56-4.56/♂ 7.07-8.87) and decreased with a BMI ≥25 kg/m² (FFMI: OR ♀ 0.03-0.04/♂ 0.01-0.04; SMI: OR ♀ 0.18-0.25/♂ 0.14-0.18). The opposite association appeared between BMI and cut-offs based on SMP.

CONCLUSION

The prevalence of low muscle mass varies widely depending on the definition, especially in persons with BMI <18.5 or ≥25 kg/m².

Stratification of Fat-Free Mass Index Percentiles for Body Composition Based on National Health and Nutrition Examination Survey III Bioelectric Impedance Data

BACKGROUND

Loss of protein mass and lower fat-free mass index (FFMI) are associated with longer length of stay, postsurgical complications, and other poor outcomes in hospitalized patients. Normative data for FFMI of U.S. populations do not exist. This work aims to create a stratified FFMI percentile table for the U.S. population using the large bioelectric impedance analysis data obtained from National Health and Nutrition Examination Surveys (NHANES).

METHODS

Fat-free mass (FFM) was calculated from the NHANES III bioelectric impedance analysis and anthropometric data for males and females ages 12 to >90 years for 3 race/ethnicities (non-Hispanic white, non-Hispanic black, and Mexican American). FFM was normalized by subject height to create an FFMI distribution table for the U.S.

POPULATION

Selected percentiles were obtained by age, sex, and race/ethnicity. Data were collapsed by race/ethnicity before and after removing obese and underweight participants to create an FFMI decile table for males and females 12 years and older for the healthy-weight U.S.

POPULATION

RESULTS

FFMI increased during adolescent growth but stabilized in the early 20s. The FFMI deciles were similar by race/ethnicity, with age group remaining relatively stable between ages 25 and 80 years. The FFMI deciles for males and females were significantly different.

CONCLUSIONS

After eliminating the obese and extremely thin, FFMI percentiles remain stable during adult years allowing creation of age- and race/ethnicity-independent decile tables for males and females. These tables allow stratification of individuals for nutrition intervention trials to depict changing nutrition status during medical, surgical, and nutrition interventions.

New specific bioelectrical impedance vector reference values for assessing body composition in the Italian-Spanish young adult population

OBJECTIVE

Specific bioelectrical impedance vector analysis (spBIVA) is a recently proposed technique for the analysis of body composition. The aim of this study was to apply spBIVA to a sample of Italian and Spanish young adults and to define the new bioelectrical references for this Western Mediterranean population.

METHODS

A sample of 440 individuals (220 from Italy, 220 from Spain; 213 men, 227 women) aged 18-30 years was considered. Anthropometric (height, weight, relaxed upper arm, waist, and calf girths) and bioelectrical (resistance, reactance; 50 kHz, 800 μA) measurements were taken. In order to verify the need for new references, specific bioelectrical values were compared to the reference values for U.S. adults and Italian elderly by tolerance ellipses and Student's t test.

RESULTS

The mean specific bioelectrical values (resistivity, Rsp, and reactivity, Xcsp, Ohm·cm) were: Rsp (332.7 ± 41.7 Ω·cm), Xcsp (44.4 ± 6.8 Ω·cm), Zsp (335.6 ± 41.9 Ω·cm) and phase (7.6 ± 0.8°) in men; Rsp (388.6 ± 60 Ω·cm), Xcsp (43.7 ± 7.5 Ω·cm), Zsp (391.0 ± 60.3 Ω·cm) and phase (6.4 ± 0.7°) in women. Italo-Spanish bioelectrical vectors were mainly distributed (>90%) in the lower part of the tolerance ellipses for U.S. young adults, due to a shorter impedance (P < 0.001), indicative of a lower percent fat mass. Compared to Italian elders, they were mainly located in the left side (>90%), due to a higher phase (P < 0.001), indicative of higher body cell mass.

CONCLUSIONS

These population and age-related differences indicate the need for new specific tolerance ellipses that can be used as references for assessing body composition in young adults from Western Mediterranean populations.

Dietary fat and fatty acid profile are associated with indices of skeletal muscle mass in women aged 18-79 years

Age-related loss of skeletal muscle mass results in a reduction in metabolically active tissue and has been related to the onset of obesity and sarcopenia. Although the causes of muscle loss are poorly understood, dietary fat has been postulated to have a role in determining protein turnover through an influence on both inflammation and insulin resistance. This study was designed to investigate the cross-sectional relation between dietary fat intake, as dietary percentage of fat energy (PFE) and fatty acid profile, with indices of skeletal muscle mass in the population setting. Body composition [fat-free mass (FFM; in kg)] and the fat-free mass index (FFMI; kg FFM/m(2)) was measured by using dual-energy X-ray absorptiometry in 2689 women aged 18-79 y from the TwinsUK Study and calculated according to quintile of dietary fat (by food-frequency questionnaire) after multivariate adjustment. Positive associations were found between the polyunsaturated-to-saturated fatty acid (SFA) ratio and indices of FFM, and inverse associations were found with PFE, SFAs, monounsaturated fatty acids (MUFAs), and trans fatty acids (TFAs) (all as % of energy). Extreme quintile dietary differences for PFE were -0.6 kg for FFM and -0.28 kg/m(2) for FFMI; for SFAs, MUFAs, and TFAs, these were -0.5 to -0.8 kg for FFM and -0.26 to -0.38 kg/m(2) for FFMI. These associations were of a similar magnitude to the expected decline in muscle mass that occurs over 10 y. To our knowledge, this is the first population-based study to demonstrate an association between a comprehensive range of dietary fat intake and FFM. These findings indicate that a dietary fat profile already associated with cardiovascular disease protection may also be beneficial for conservation of skeletal muscle mass.

Reference values for physical performance measures in the aging working population

OBJECTIVE

The aim of this study was to determine reference physical performance values in older aging workers.

BACKGROUND

Cross-sectional physical performance measures were collected for 736 manufacturing workers to assess effects of work and nonwork factors on age-related changes in musculoskeletal function and health.

METHOD

Participants underwent surveys and physical testing that included bioelectrical impedance analysis, range-of-motion measures, exercise testing, and dynamic assessment.

RESULTS

Physical characteristics, such as blood pressure and body fat percentage, were comparable to published values. Dynamic and range-of-motion measurements differed from published normative results. Women had age-related decreases in cervical extension and lateral rotation. Older men had better spinal flexion than expected. Predicted age-related decline in lower-extremity strength and shoulder strength in women was not seen. Men declined in handgrip, lower-extremity strength, and knee extension strength, but not trunk strength, across age groups. There was no appreciable decline in muscle fatigue at the trunk, shoulder, and knee with aging for either gender, except for the youngest age group of women.

CONCLUSION

Normative values may underestimate physical performance in "healthy" older workers, thereby underappreciating declines in less healthy older workers. Work may be preservative of function for a large group of selected individuals. A "healthy worker effect" may be greater for musculoskeletal disease and function than for heart disease and mortality.

APPLICATION

Clinicians and researchers studying musculoskeletal function in older workers can use a more specific set of reference values.

Dietary fat and fatty acid profile are associated with indices of skeletal muscle mass in women aged 18-79 years

Age-related loss of skeletal muscle mass results in a reduction in metabolically active tissue and has been related to the onset of obesity and sarcopenia. Although the causes of muscle loss are poorly understood, dietary fat has been postulated to have a role in determining protein turnover through an influence on both inflammation and insulin resistance. This study was designed to investigate the cross-sectional relation between dietary fat intake, as dietary percentage of fat energy (PFE) and fatty acid profile, with indices of skeletal muscle mass in the population setting. Body composition [fat-free mass (FFM; in kg)] and the fat-free mass index (FFMI; kg FFM/m(2)) was measured by using dual-energy X-ray absorptiometry in 2689 women aged 18-79 y from the TwinsUK Study and calculated according to quintile of dietary fat (by food-frequency questionnaire) after multivariate adjustment. Positive associations were found between the polyunsaturated-to-saturated fatty acid (SFA) ratio and indices of FFM, and inverse associations were found with PFE, SFAs, monounsaturated fatty acids (MUFAs), and trans fatty acids (TFAs) (all as % of energy). Extreme quintile dietary differences for PFE were -0.6 kg for FFM and -0.28 kg/m(2) for FFMI; for SFAs, MUFAs, and TFAs, these were -0.5 to -0.8 kg for FFM and -0.26 to -0.38 kg/m(2) for FFMI. These associations were of a similar magnitude to the expected decline in muscle mass that occurs over 10 y. To our knowledge, this is the first population-based study to demonstrate an association between a comprehensive range of dietary fat intake and FFM. These findings indicate that a dietary fat profile already associated with cardiovascular disease protection may also be beneficial for conservation of skeletal muscle mass.

Soy proteins and isoflavones reduce interleukin-6 but not serum lipids in older women: a randomized controlled trial

Soy foods contain several components, notably, isoflavones and amino acids, that may improve cardiovascular health. We evaluated the long-term effect of soy protein and/or soy isoflavones supplementation on serum lipids and inflammatory markers using a 1-year randomized, double-blind, placebo-control, clinical trial in 131 healthy ambulatory women older than 60 years. We hypothesized that soy protein, in combination with isoflavones, would have the largest positive effect on coronary heart disease risk factors (serum lipids and inflammatory markers) compared with either intervention alone and that, within groups receiving isoflavones, equol producers would have more positive effects on coronary heart disease risk factors than nonequol producers. After a 1-month baseline period, participants were randomized into 1 of 4 intervention groups: soy protein (18 g/d) and isoflavone tablets (105 mg/d isoflavone aglycone equivalents), soy protein and placebo tablets, control protein and isoflavone tablets, or control protein and placebo tablets. T Tests were used to assess differences between equol and nonequol producers. Ninety-seven women completed the trial. Consumption of protein powder and isoflavone tablets did not differ among groups, and compliance with study powder and tablets was 79% and 90%, respectively. After 1 year, in the entire population, there were either no or little effects on serum lipids and inflammatory markers, regardless of treatment group. Equol producers, when analyzed separately, had significant improvements in total cholesterol/high-density lipoprotein and low-density lipoprotein/high-density lipoprotein ratios (-5.9%, P = .02; -7.2%, P = .04 respectively). Soy protein and isoflavone (either alone or together) did not impact serum lipids or inflammatory markers. Therefore, they should not be considered an effective intervention to prevent cardiovascular disease because of lipid modification in healthy late postmenopausal women lacking the ability to produce equol.

The use of bioelectrical impedance analysis for body composition in epidemiological studies

BACKGROUND/OBJECTIVES

Bioelectrical impedance analysis (BIA) is a relatively simple, inexpensive and non-invasive technique to measure body composition and is therefore suitable in field studies and larger surveys.

SUBJECTS/METHODS

We performed an overview of BIA-derived body fat percentages (BF%) from 55 published studies of healthy populations aged 6-80 years. In addition, the relationship between body mass index (BMI) and body composition is documented in the context of BIA as a good alternative to closely differentiate which composition of the body better relates to the risk of cardiovascular diseases (CVDs)and all-cause mortality.

RESULTS AND CONCLUSIONS

BIA-estimated percentage of BF varies greatly with population and age. BIA-estimated BF% is directly and closely related to various health outcomes such as CVDs, which is in contrast to BMI where both high and low BMIs are associated with increased risk of developing chronic diseases. Studies, among others using BIA, suggest that low BMI may reflect low muscle and high BMI fat mass (FM). BIA-derived lean and FM is directly associated with morbidity and mortality. To the contrary, BMI is rather of limited use for measuring BF% in epidemiological studies.

Fat, muscles, and wages

Recent studies in health economics have generated two important findings: that as a measure of fatness the body mass index (BMI) is biased; and that, when it comes to analyzing wage correlates, both fat-free mass (FFM) and body fat (BF) are better suited to the task. We validate these findings for Germany using the BIAdata Base Project and the German Socio-Economic Panel. While we find no significant correlation between BMI and wages in any of our models, simple linear regression models featuring both contemporary and time-lagged fatness measures indicate that FFM and, to a lesser extent, BF are associated with hourly wages: more specifically, the relationship between FFM/BF and hourly wages is about two to three times higher for females than for males. In contrast, fixed-effects models indicate that there is no correlation between hourly wages and both FFM and BF with one exception: a significant correlation (and one in line with expectations) is found to be the rule among job changers.

External cross-validation of bioelectrical impedance analysis for the assessment of body composition in Korean adults

Bioelectrical impedance analysis (BIA) models must be validated against a reference method in a representative population sample before they can be accepted as accurate and applicable. The purpose of this study was to compare the eight-electrode BIA method with DEXA as a reference method in the assessment of body composition in Korean adults and to investigate the predictive accuracy and applicability of the eight-electrode BIA model. A total of 174 apparently healthy adults participated. The study was designed as a cross-sectional study. FM, %fat, and FFM were estimated by an eight-electrode BIA model and were measured by DEXA. Correlations between BIA_%fat and DEXA_%fat were 0.956 for men and 0.960 for women with a total error of 2.1%fat in men and 2.3%fat in women. The mean difference between BIA_%fat and DEXA_%fat was small but significant (P < 0.05), which resulted in an overestimation of 1.2 ± 2.2%fat (95% CI: -3.2-6.2%fat) in men and an underestimation of -2.0 ± 2.4%fat (95% CI: -2.3-7.1%fat) in women. In the Bland-Altman analysis, the %fat of 86.3% of men was accurately estimated and the %fat of 66.0% of women was accurately estimated to within 3.5%fat. The BIA had good agreement for prediction of %fat in Korean adults. However, the eight-electrode BIA had small, but systemic, errors of %fat in the predictive accuracy for individual estimation. The total errors led to an overestimation of %fat in lean men and an underestimation of %fat in obese women.

Poor physical function in elderly women in low-level aged care is related to muscle strength rather than to measures of sarcopenia

Purpose:

To determine the prevalence of sarcopenia and investigate relationships among body composition, muscle strength, and physical function in elderly women in low-level aged care.

Subjects and methods:

Sixty-three ambulatory women (mean age 86 years) participated in this cross-sectional study where body composition was determined by dual energy X-ray absorptiometry (DXA); ankle, knee, and hip strength by the Nicholas Manual Muscle Tester; and physical function by ‘timed up and go’ (TUG) and walking speed (WS) over 6 meters. Body composition data from a female reference group (n = 62, mean age 29 years) provided cut-off values for defining sarcopenia.

Results:

Elderly women had higher body mass index (P < 0.001), lower lean mass (P < 0.001), and higher fat mass (P < 0.01) than the young reference group. Only a small proportion (3.2%) had absolute sarcopenia (defined by appendicular skeletal muscle mass/height squared) whereas 37% had relative sarcopenia class II (defined by percentage skeletal muscle mass). Scores for TUG and WS indicated relatively poor physical function, yet these measures were not associated with muscle mass or indices of sarcopenia. In multivariate analysis, only hip abductor strength predicted both TUG and WS (both P = 0.01).

Conclusion:

Hip strength is a more important indicator of physical functioning than lean mass. Measurement of hip strength may therefore be a useful screening tool to detect those at risk of functional decline and requirement for additional care. Further longitudinal studies with a range of other strength measures are warranted.

Body mass index (BMI), body composition and mortality of nursing home elderly residents

The body mass index (BMI) is a key marker of nutritional status among older patients, but does not reflect changes in body composition, The aim of the present study was to investigate BMI levels and body composition in a sample of disabled nursing home residents, and to study possible interrelations between BMI, fat-free body mass (FFM), body fat mass (BFM), skeletal muscle mass (SMM) and 1-year mortality rates. FFM and SMM were assessed by 24-h urine creatinine excretion and BFM as the difference between BMI and FFM. We calculated relative risk (RR) and odds ratio (OR) of 1-year mortality, associated with different levels of BMI, FFM index (where index=value/height(2)), SMM index and BFM index in 82 disabled institutionalized elderly patients. One-year mortality rate was 29.3%. Adjusted relative risk of mortality of low BMI patients was 1.45 (95% CI=0.73-2.89; OR=1.73) and 0.63 (95% CI=0.33-1.60; OR=0.72) in high BMI. Risk of mortality was higher in those having low FMM index or SMM index (RR=2.42, 95% CI=0.36-16.18; OR=2.55 and RR=3.22, 95% CI=0.78-13.32; OR=3.67, respectively). It is concluded that low FFM and SMM indexes among disabled nursing home residents are far better predictors than BMI for 1-year mortality estimation.

Obesity markers and estimated 10-year fatal cardiovascular risk in Switzerland

BACKGROUND AND AIM

There is an ongoing debate on which obesity marker better predicts cardiovascular disease (CVD). In this study, the relationships between obesity markers and high (>5%) 10-year risk of fatal CVD were assessed.

METHODS AND RESULTS

A cross-sectional study was conducted including 3047 women and 2689 men aged 35-75 years. Body fat percentage was assessed by tetrapolar bioimpedance. CVD risk was assessed using the SCORE risk function and gender- and age-specific cut points for body fat were derived. The diagnostic accuracy of each obesity marker was evaluated through receiver operating characteristics (ROC) analysis. In men, body fat presented a higher correlation (r=0.31) with 10-year CVD risk than waist/hip ratio (WHR, r=0.22), waist (r=0.22) or BMI (r=0.19); the corresponding values in women were 0.18, 0.15, 0.11 and 0.05, respectively (all p<0.05). In both genders, body fat showed the highest area under the ROC curve (AUC): in men, the AUC (95% confidence interval) were 76.0 (73.8-78.2), 67.3 (64.6-69.9), 65.8 (63.1-68.5) and 60.6 (57.9-63.5) for body fat, WHR, waist and BMI, respectively. In women, the corresponding values were 72.3 (69.2-75.3), 66.6 (63.1-70.2), 64.1 (60.6-67.6) and 58.8 (55.2-62.4). The use of the body fat percentage criterion enabled the capture of three times more subjects with high CVD risk than the BMI criterion, and almost twice as much as the WHR criterion.

CONCLUSION

Obesity defined by body fat percentage is more related with 10-year risk of fatal CVD than obesity markers based on WHR, waist or BMI.

Does sexual selection explain human sex differences in aggression?

I argue that the magnitude and nature of sex differences in aggression, their development, causation, and variability, can be better explained by sexual selection than by the alternative biosocial version of social role theory. Thus, sex differences in physical aggression increase with the degree of risk, occur early in life, peak in young adulthood, and are likely to be mediated by greater male impulsiveness, and greater female fear of physical danger. Male variability in physical aggression is consistent with an alternative life history perspective, and context-dependent variability with responses to reproductive competition, although some variability follows the internal and external influences of social roles. Other sex differences, in variance in reproductive output, threat displays, size and strength, maturation rates, and mortality and conception rates, all indicate that male aggression is part of a sexually selected adaptive complex. Physical aggression between partners can be explained using different evolutionary principles, arising from the conflicts of interest between males and females entering a reproductive alliance, combined with variability following differences in societal gender roles. In this case, social roles are particularly important since they enable both the relatively equality in physical aggression between partners from Western nations, and the considerable cross-national variability, to be explained.

Effect of fluid and food intake on the body composition evaluation of elderly persons

BACKGROUND

Several studies have shown that liquid and food intake interfere with the evaluation of body composition in adults. However, since there are no reports about this interference in the elderly population, the need to fast for this evaluation may be dispensable.

OBJECTIVES

The objective of the present study was to assess the influence of liquid and solid food on the measurement of body composition by bioelectrical impedance analysis (BIA) and by dual energy X-ray absorptiometry (DXA).

DESIGN

Forty-one male volunteers aged 62 to 87 years participated in the study. The subjects were submitted to evaluation of body composition by DXA and BIA under fasting conditions and 1 hour after the ingestion of breakfast (500 ml of orange juice and one 50 g bread roll with butter).

RESULTS

There was no significant difference in the variables fat-free mass (FFM) or fat mass (FM) between the fasting condition and the evaluation performed 1 hour after the meal as measured by BIA or DXA. There was also no significant difference when the same variables were compared between methods.

CONCLUSION

In the present study, the ingestion of 500 ml orange juice and of one bread roll with butter by elderly subjects did not affect the results of the parameters of body composition determined by BIA or DXA. Thus, these exams could be performed without the rigor of fasting, often poorly tolerated by the elderly.

Low resting energy expenditure in Asians can be attributed to body composition

OBJECTIVE

To compare resting energy expenditure (REE) between Asians and whites after adjusting for fat-free mass measured with a two- or more-compartment model.

METHODS AND PROCEDURES

Participants were 10 white men (28 +/- 3 years), 10 Asian men (30 +/- 4 years), 10 white women (22 +/- 4 years), and 11 Asian women (31 +/- 7 years). REE was measured with a ventilated hood system under strictly controlled conditions. Body composition was measured with a two-compartment model based on body mass (BM) and body volume (hydrodensitometry), a three-compartment model adding total body water (TBW) (deuterium dilution), and a four-compartment model incorporating bone mass (dual-energy X-ray absorptiometry (DXA)) as well. Lean BM in the trunk and in the extremities was assessed with DXA. All measurements were performed at Maastricht University. Measurements on Asian subjects were performed within 3 months after their arrival in the Netherlands.

RESULTS

Absolute REE was lower in Asians (5.87 +/- 0.91 MJ/day) than in whites (7.00 +/- 1.11 MJ/day). There was no significant difference in REE between the two races after adjustment for fat-free mass.

DISCUSSION

There were no significant differences in REE between Asians and whites after adjustment for differences in body composition based on a two- or more-compartment model.

Prevalence of normal weight obesity in Switzerland: effect of various definitions

BACKGROUND

Normal weight obesity (NWO) is defined as an excessive body fat associated with a normal body mass index (BMI < 25 kg/m(2)), but its prevalence in the general population is unknown.

AIM OF THE STUDY

To assess the prevalence of NWO in Switzerland according to different cut points used to define excess body fat.

METHODS

Cross-sectional study including 3,213 women and 2,912 men aged 35-75 years. Body fat was assessed by bioelectrical impedance analysis and prevalence of NWO was assessed using four previously published definitions for excess body fat.

RESULTS

Percent body fat increased with age: in men, the values (mean +/- SD) were 20.2 +/- 5.4, 23.0 +/- 5.4, 26.3 +/- 5.2 and 28.2 +/- 4.6 for age groups 35-44, 45-54, 55-64 and 65-75 years, respectively; the corresponding values for women were 29.9 +/- 7.8, 33.1 +/- 7.4, 36.7 +/- 7.5 and 39.6 +/- 6.9. In men, prevalence of NWO was <1% irrespective of the definition used. Conversely, in women, a 1- to 20-fold difference (from 1.4 to 27.8%) in NWO prevalence was found. The prevalence of NWO increased with age when age-independent cut points were used in women, but not in men.

CONCLUSIONS

Prevalence of NWO is low in the general population and higher in women than in men. The prevalence is highly dependent on the criteria used to define excess body fat, namely in women. The use of gender- and age-specific cut points to define excess body fat is better than fixed or gender-specific only cut points.

Incidence of hip fractures in Korea

Osteoporosis is a major public health problem in both Western and Asian populations. Because the aged population in Korea is increasing, the number of osteoporotic fractures is thought to be also increasing. However, there has been no nationwide analysis of osteoporotic fractures in Korea. We analyzed the incidence and cost of hip fracture from 2001 to 2004 by using data from the Health Insurance Review Agency, Korea. In the over 50 years age group, the number of hip fractures in women increased from 250.9/100,000 persons in 2001 to 262.8/100,000 in 2004, a 4.7% increase. However, that in men decreased from 162.8/100,000 in 2001 to 137.5/100,000 in 2004, a 15.5% decrease. Direct medical care costs of hip fracture increased from $62,707,697 in 2001 to $65,200,035 in 2004, and the proportional cost of hip fractures in the national medical costs increased by 4.5% over 4 years (from 0.200% in 2001 to 0.209% in 2004). On analysis of the population-based data obtained from the whole country from 2001 to 2004, the incidence rate of hip fractures in women, not in men, and its cost have increased in Korea. The gender distribution of hip fractures underlines the need for aggressive intervention in osteoporosis in elderly women.

Use of bioelectrical impedance analysis in the evaluation, treatment, and prevention of overweight and obesity

PURPOSE

To present an overview of bioelectrical impedance analysis (BIA) and to familiarize nurse practitioners (NPs) with the potential benefits of using BIA in prevention, monitoring, and long-term follow-up of healthy individuals and those with chronic conditions (e.g., obesity).

DATA SOURCES

Original research articles and comprehensive review articles identified through Medline, CINAHL, OVID, and electrical engineering databases.

CONCLUSIONS

Obtaining serial measurements of percent body fat using BIA can identify patients at greatest health risk and gives NPs an additional tool to assess treatment response in patients seeking to lose or maintain body weight and/or increase muscle mass.

IMPLICATIONS FOR PRACTICE

Traditionally, height/weight tables and body mass index have been used to assess body composition and diagnose overweight and obesity. More recently, BIA has emerged as a portable and simple-to-operate instrument to evaluate body composition in the clinical setting.

Eight-Year Longitudinal Changes in Body Composition in Healthy Swiss Adults

OBJECTIVE

Significant changes in body composition occur during lifetime. This longitudinal study (8.0 +/- 0.8 yrs) in a cohort of healthy sedentary and physically active men (n = 78) and women (n = 53), aged 20 to 74 yr describes: 1) the longitudinal changes in weight and body composition and 2) their associations with age and physical activity.

METHOD

Fat-free mass (FFM) and body fat (BF) were assessed by bioelectrical impedance analysis (BIA). Subjects who regularly performed >3 hours per week of endurance type physical activity were classified as "Active". Others were classified as "Sedentary". Subjects were also separated by age (<45 yr vs > or =45 yr).

RESULTS

FFM increased by 1.7 +/- 2.8 kg in men <45 yr who gained 4.0 +/- 5.0 kg of body weight and was maintained (0.5 +/- 1.6 kg) in women <45 y who gained 1.6 +/- 3.0 kg of weight. A weight gain of 1.2 +/- 3.3 kg in men > or =45 yr was accompanied by stable FFM (-0.1 +/- 2.3 kg), and of 1.0 +/- 3.2 kg was accompanied by a loss of FFM in women > or =45 yr. In active men > or =45 yr, maintenance of FFM was associated with smaller weight gains than in sedentary; sedentary men > or =45 yr decreased FFM with larger weight gains than active subjects. Sedentary women <45 yr were able to gain FFM; the active women maintained, but did not gain FFM with smaller weight gains than in sedentary women. FFM decreased in >/=45 yr women despite of small weight gains.

CONCLUSION

Weight change is clearly associated with a change in FFM. Weight gain is necessary to offset age-related FFM loss between 20 and 74 yrs. In active men, a FFM increase was associated with less weight gain than sedentary men. Future studies should evaluate the threshold of weight change and the level of physical activity necessary to prevent age-related losses of FFM.

Factors associated with obesity in an adult Mediterranean population: influence on plasma lipid profile

OBJECTIVE

The aim of the study was to identify factors associated with obesity, and their influence on plasma lipid profile in an adult Mediterranean population.

DESIGN

The data were obtained from a cross-sectional epidemiological survey.

SETTING

The study population resided in Andalusia, a western Mediterranean region in southern Spain.

SUBJECTS

The survey was carried out with a random sample of 3421 subjects (1747 men, 1674 women) between 25 and 60 years of age. Blood samples were obtained for biochemical assays in a random subsample of 340 subjects (167 men, 173 women).

INTERVENTIONS

Food consumption was assessed by 48-h recall. Height, weight, triceps, biceps, subscapular and suprailiac skinfolds, mid-upper arm, waist (WC) and hip circumferences, glucose, total cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides were measured. Information about lifestyles was obtained with a questionnaire.

RESULTS

Of the adult population we studied, 18.9% were obese (body mass index [BMI] > or = 30 kg/m2). A larger proportion of men than women were overweight, but the opposite was found for obesity. Mean plasma lipid values were not modified significantly by obesity or lifestyle factors, and were within the normal range. Sex, age, physical exercise and lower educational level were associated directly with the risk of obesity, and smoking was associated inversely with the risk of obesity. In obese smokers WC and waist-hip ratio were larger, and levels of HDL-cholesterol were lower (p < 0.05) than in obese nonsmokers. Glucemia was higher in obese persons who consumed alcohol (p < 0.05) than in obese persons who did not consume alcohol. The risk of hypercholesterolemia and high levels of LDL-cholesterol was associated only with age, and the risk of low levels of HDL-cholesterol was associated only with high WC.

CONCLUSION

Our results provide an estimate of the prevalence of obesity in the adult population in southern Spain, and of the associated factors. Sex, age, leisure-time physical exercise and educational level appear to influence obesity. Only age and WC but not BMI were associated with a risk of dyslipidemia. No dietary associations were observed between energy or macronutrient intake and plasma lipid concentrations in overweight or obese persons.