Comparison of skeletal muscle mass to fat-free mass ratios among different ethnic groups

Background

Asians seem to have less skeletal muscle mass (SMM) than other ethnic groups, but it is not clear whether relative SMM, i.e., SMM / height square or SMM to fat-free mass (FFM) ratio, differs among different ethnic groups at the same level of body mass index (BMI).

Objective

To compare the SMM to fat-free mass (FFM) ratio as well as anthropometric variables and body composition among 3 ethnic groups.

Design, setting, and participants

Three hundred thirty-nine Japanese, 343 Brazilian, and 183 German men and women were recruited for this cross-sectional study.

Measurements

Muscle thickness (MTH) and subcutaneous fat thickness (FTH) were measured by ultrasound at nine sites on the anterior and posterior aspects of the body. FTH was used to estimate the body density, from which fat mass and fat-free mass (FFM) was calculated by using Brozek equation. Total SMM was estimated from ultrasound-derived prediction equations.

Results

Percentage body fat was similar among the ethnic groups in men, while Brazilians were higher than Japanese in women. In German men and women, absolute SMM and FFM were higher than in their Japanese and Brazilians counterparts. SMM index and SMM:FFM ratios were similar among the ethnic groups in women, excluding SMM:FFM ratio in Brazilian. In men, however, these relative values (SMM index and SMM:FFM ratio) were still higher in Germans. After adjusting for age and BMI, the SMM index and SMM:FFM ratios were lower in Brazilian men and women compared with the other two ethnic groups, while the SMM index and SMM:FFM ratios were similar in Japanese and German men and women, excluding SMM:FFM ratio in women.

Conclusion

Our results suggest that relative SMM is not lower in Asian populations compared with European populations after adjusted by age and BMI.     

Assessment of fat-free mass using bioelectrical impedance measurements of the human body

A method which involves the measurement of bioelectrical resistive impedance (R) for the estimation of human body composition is described. This method is based upon the principle that the electrical conductivity of the fat-free tissue mass (FFM) is far greater than that of fat. Determinations of R were made in 37 healthy men aged 28.8 +/- 7.1 yr (mean +/- SD) using an electrical impedance plethysmograph with a four electrode arrangement that introduces a painless signal (800 microA at 50 kHz) into the body. FFM was assessed by hydrodensitometry and ranged from 44.6-98.1 kg. Total body water (TBW) determined by D2O dilution and total body potassium (TBK) from whole body counting were 50.6 +/- 10.3 L and 167.5 +/- 38.1 g, respectively. Test-retest correlation coefficient was 0.99 for a single R measurement and the reliability coefficient for a single R measurement over 5 days was 0.99. Linear relationships were found between R values and FFM (r = -0.86), TBW (r = -0.86), and TBK (r = -0.79). Significant (p less than 0.01) increases in the correlation coefficients were observed when the predictor Ht2/R was regressed against FFM (r = 0.98), TBW (r = 0.95), AND TBK (r = 0.96). These data indicate that the bioelectrical impedance technique is a reliable and valid approach for the estimation of human body composition. This method is safe, noninvasive, provides rapid measurements, requires little operator skill and subject cooperation, and is portable. Further validation of this method is recommended in subjects with abnormal body composition.     

Obesity and lipid-related parameters for predicting metabolic syndrome in Chinese elderly population

Background

The present study evaluated the predictive ability of five known “best” obesity and lipid-related parameters, including body mass index (BMI), waist-to-height ratio (WHtR), triglyceride-to-high-density-lipoprotein-cholesterol (TG/HDL-C), lipid accumulation product (LAP) and visceral adiposity index (VAI), in identifying metabolic syndrome (MetS) in Chinese elderly population.

Methods

A total of 6722 elderly Chinese subjects (≥60?years) were recruited into our community-based cross-sectional study from April 2015 to July 2017. The anthropometrics, blood pressure, fasting plasma glucose, blood lipid profiles, family history and health-related behaviours were assessed.

Results

The prevalence of MetS was 40.4% (32.5% in males and 47.2% in females). With the increase in the number of MetS components (from 0 to 5), all the five parameters showed an increase trend in both genders (all P for trend <?0.001). According to receiver operating characteristic curve (ROC) analyses, all the five parameters performed high predictive value in identifying MetS. The statistical significance of the areas under the curves (AUCs) differences suggested that the AUCs of LAP were the greatest among others in both genders (AUCs were 0.897 in males and 0.875 in females). The optimal cut-off values of LAP were 26.35 in males and 31.04 in females. After adjustment for potentially confounding factors, LAP was strongly associated with the odds of having MetS in both genders, and ORs for MetS increased across quartiles using multivariate logistic regression analysis (P?<?0.001).

Conclusion

LAP appeared to be a superior parameter for predicting MetS in both Chinese elderly males and females, better than VAI, TG/HDL-C, WHtR and BMI.

     

Age-related differences in fat-free mass, skeletal muscle, body cell mass and fat mass between 18 and 94 years

OBJECTIVE: To determine (1) lean and fat body compartments, reflected by fat-free mass (FFM), appendicular skeletal muscle mass (ASMM), body cell mass (BCM), total body potassium (TBK), fat mass and percentage fat mass, and their differences between age groups in healthy, physically active subjects from 18 to 94 y of age; and (2) if the rate of decrease in any one of the parameters by age might be accelerated compared to others. METHODS: A total of 433 healthy ambulatory Caucasians (253 men and 180 women) aged 18--94 y were measured by dual-energy X-ray absorptiometry (DXA) and whole body scintillation counter (TBK counter) using a large sodium iodide crystal (203 mm diameter). RESULTS: The ASMM change (-16.4 and -12.3% in men and women, respectively) in >75 y-old compared to 18 to 34-y-old subjects was greater than the FFM change (-11.8 and -9.7% in men and women, respectively) and this suggests that skeletal muscle mass decrease in older subjects was proportionally greater than non-skeletal muscle mass. BCM (-25.1 and -23.2% in men and women, respectively) and TBK differences were greater than the differences in FFM or ASMM suggesting altered composition of FFM in older subjects. Women had lower peak FFM, ASMM, BCM and TBK than men. CONCLUSIONS: The decline in FFM, ASMM, BCM and TBK is accelerated in men and women after 60 y of age and FFM, ASMM, BCM and TBK are significantly lower than in younger subjects. Fat mass continued to increase until around 75 y.     

Fat-free mass in relation to stature: ratios of fat-free mass to height in children, adults, and elderly subjects

A cross-sectional relationship of fat-free mass to height expressed as a ratio (FFM:ht) is presented for 1103 people aged 6-86 y. Data are presented for 13 specific age groups by gender. By providing information for normal, healthy individuals, these data may be of comparative value for nutritionists and clinicians concerned with body composition of patients with wasting diseases. The data were collected over 20 y in our laboratory by using the same densitometric procedure. A significant increase in FFM:ht occurs during the preadolescent and adolescent years. The adolescent spurt continues for a longer period for boys than for girls, resulting in a significant gender difference beginning at approximately age 16 y and continuing throughout adulthood. A decline in FFM:ht, not statistically significant, appears to occur in men greater than 60 y of age, and a significant decline occurs among women greater than 50 y of age (alpha less than 0.01). Thus, both gender- and age-related trends that have implications for the interpretation of comparative body-composition status are suggested.     

Anthropometric measurements in the elderly population of Santiago, Chile

OBJECTIVE: There are few studies on anthropometry and nutritional status in large and representative samples of elderly populations in Chile and South America. We describe age and sex differences in weight, height, body mass index, knee height, waist circumference, midarm circumference, triceps skinfold thickness, arm muscle area, and calf circumference in Chilean elderly subjects. METHODS: This was a population-based, cross-sectional study. A total of 1220 elderly persons (819 women and 411 men; age range, 60-99 y) were recruited in the city of Santiago (Chile) through a probabilistic sampling procedure carried out from October to December 1999. RESULTS: Men were significantly heavier and taller than women in all age groups, whereas body mass index values were significantly higher in women than in men. All anthropometric variables showed a decrease in average values with aging in men and women. The apparent negative slopes for the decline in average values of body weight with aging was of greater magnitude in women than in men (-0.42 kg/y and -0.54 kg/y in male and female subjects, respectively). However, significant age x sex interaction was detected only for triceps skinfold thickness. In women, quadratic terms for age provided a significantly better fit than did the simple linear model for the association between age and weight, body mass index, waist circumference, triceps skinfold thickness, calf circumference, or midarm circumference. CONCLUSION: These observations indicated that body weight changes associated with aging might be more severe in Chilean women than in men, probably determining a differential pattern of lean and fat mass loss.     

Anthropometric assessment of muscularity during growth: estimating fat-free mass with 2 skinfold-thickness measurements is superior to measuring midupper arm muscle area in healthy prepubertal children

BACKGROUND: Anthropometric measurements are widely used to determine body composition, especially in children. OBJECTIVE: Our aim was to compare 2 of the simplest anthropometry-based equations available for determining nutritional status and muscularity in children and adolescents, examined in relation to other methodologically independent muscle variables. DESIGN: Midupper arm muscle area (UAMA) and fat-free mass (FFM) according to the equations of Slaughter et al (Hum Biol 1988;60:709-23), as well as separate biochemical, physical, and radiologic muscle variables, were determined cross-sectionally in 91 males and 91 females aged 6-18 y. The ability of UAMA and FFM to estimate muscularity, as measured by 24-h creatinine excretion, grip force, and peripheral quantitative computer tomography analysis of forearm muscle, was compared after dividing the study population into prepubertal and pubertal groups. RESULTS: Before puberty, correlations of all 3 muscularity variables were higher with FFM than with UAMA in both males and females. Multiple regression analyses confirmed FFM to be the predominant predictor, with partial R(2) >/= 0.68 (P < 0.001). However, in puberty, FFM did not consistently show this major influence. Only before puberty did FFM provide a significantly better fit (P < 0.05) than did UAMA for 2 of the 3 muscularity variables in each sex. CONCLUSIONS: The FFM estimate proved to be the better predictor for muscularity in healthy prepubertal children and is on a par with UAMA during puberty. FFM can be recommended as a simple anthropometric method to assess nutritional status before puberty, at least in healthy children.     

Factors predicting mortality in a total population sample of the elderly.

Between 1977 and 1979 an age stratified sample of people 65 years and over living in the community and in institutions in Gisborne, New Zealand was assessed medically and socially. This sample was followed and reviewed in 1982. At follow up 308 subjects were seen, 227 had died, and 24 had left the area. Factors predicting mortality were assessed. Using a log rank test, factors predicting mortality included age, impaired mental function, functional disability, urinary incontinence, prescribed drugs, pulse pressure, erythrocyte sedimentation rate (ESR), systolic pressure, cardiovascular drugs, and falls. However, a number of these factors increased in prevalence with age. Using a Cox's regression analysis for factors predicting mortality after controlling for age, the following were found to be significant predictors: impaired mental function; functional disability; urinary incontinence; prescribed drugs, ESR and falls. A proportional hazards general linear model showed that the major predictors of mortality in old age were markers of established disease.     

Comparison of fat-free mass index and fat mass index in Chinese adults

Background/Objectives:To compare the characteristics of body composition for different gender and age in a large number of apparently healthy Chinese subjects, and to determine reference values for fat-free mass index (FFMI) and fat mass index (FMI).Subjects/Methods:In total, 61?382 Chinese adults (age range: 18-92 years) were consecutively enrolled into the study. Body composition was measured using bioelectrical impedance analysis with a tetrapolar impedance meter.Results:The skeletal muscle mass, fat-free mass (FFM), FFMI and body mass index (BMI) were significantly higher in men than in women (P<0.05), but FM% and FMI were significantly higher in women (P<0.05). In the group with normal BMI (BMI 18.5-23.9?kg/m(2), 18-92?years), the reference values (5th-95th percentile) of FM%, FFMI and FMI were 9.7-34.5%, 14.15-19.76 and 1.99-7.75?kg/m(2) in men, and 18.1-35.8%, 13.82-17.89 and 3.68-8.16?kg/m(2) in women, respectively.Conclusions:Reference intervals for FFMI and FMI could be of practical value for the clinical evaluation of a deficit in FFM with or without excess FM for a given age category, complementing the classical concept of BMI in a more qualitative manner, although these indices are only suggestive indications for the degree of obesity. In contrast to BMI, similar reference ranges of FFMI seem to be more utilizable with advancing age.     

Reliability of fat-free mass estimates derived from total-body electrical conductivity measurements as influenced by changes in extracellular fluid volume

Our study addresses the concern that the relationship between total-body electrical conductivity (TOBEC) measurements and the fat-free mass (FFM) or total-body water (TBW) of an individual is altered if significant fluid and electrolyte changes occur. Body composition and TOBEC measurements were obtained from 11 healthy miniature piglets before and after an intraperitoneal injection of physiological saline. The procedure expanded the extracellular fluid (ECF) volume by 11.8-34.1%, which represented an average increase in TBW of 7.9%. The linear regressions that related the preinjection and postinjection estimates of TBW or FFM to the corresponding transformed TOBEC signals were the same. Thus, the prediction equations derived for the untreated piglets accurately predicted both TBW and FFM in the piglets whose volume was expanded. These data suggest that prediction equations derived from healthy subjects should be equally valid for subjects with altered fluid status.     

Reexamination of the relationship of resting metabolic rate to fat-free mass and to the metabolically active components of fat-free mass in humans.

The ratio of resting metabolic rate (RMR) to fat-free mass (FFM) is often used to compare individuals of different body sizes. Because RMR has not been well described over the full range of FFM, a literature review was conducted among groups with a wide range of FFM. It included 31 data sets comprising a total of 1111 subjects: 118 infants and preschoolers, 323 adolescents, and 670 adults; FFM ranged from 2.8 to 106 kg. The relationship of RMR to FFM was found to be nonlinear and average slopes of the regression equations of the three groups differed significantly (P less than 0.0001). For only the youngest group did the intercept approach zero. The lower slopes of RMR on FFM, at higher measures of FFM, corresponded to relatively greater proportions of less metabolically active muscle mass and to lesser proportions of more metabolically active nonmuscle organ mass. Because the contribution of FFM to RMR is not constant, an arithmetic error is introduced when the ratio of RMR to FFM is used. Hence, alternative methods should be used to compare individuals with markedly different FFM.     

Total-body electrical conductivity (TOBEC): relationship to estimates of muscle mass, fat-free weight, and lean body mass

A comparison of methods for estimating body composition (BC) of 12 subjects was made by using fat-free weight from total-body electrical conductivity (FFWT), muscle mass from 3-methylhistidine excretion (MM3MH) and creatinine excretion (MMCRE), fat-free weight from hydrostatic weighing (FFWBD), and lean body mass from whole-body potassium counting (LBMK). Data were analyzed for day-to-day variability and regression analyses were applied to compare the different methods of measuring BC. Mean values (+/- SEM, kg) for the estimates were 53.9 +/- 3.5 (FFWT), 26.9 +/- 2.9 (MM3MH), 25.3 +/- 2.5 (MMCRE), 53.2 +/- 3.6 (FFWBD), and 52.8 +/- 3.5 (LBMK). Regression analyses revealed that TOBEC estimates of fat-free weight had an adjusted r2 (+/- SEE, kg) of 0.95 +/- 2.2, 0.50 +/- 7.9, 0.95 +/- 1.8, and 0.88 +/- 4.0 for MM3MH, MMCRE, FFWBD, and LBMK, respectively. It was concluded that TOBEC is a potentially reliable method for estimating the muscle mass within the fat-free compartment, as well as fat-free weight and lean body mass.     

Dynamic assessment of fat-free mass during catabolism and recovery

Catabolism of fat-free mass affects both the quality of life and survival of patients. Because of variations in fluid status during acute illness, changes in body weight are difficult to evaluate and interpret during treatment. Nutritional assessment should therefore evaluate fat-free and fat mass changes during metabolic stress and catabolism. We have chosen to discuss bioelectrical impedance analysis, including the various bioelectrical impedance analysis techniques (i.e. multi-frequency and bioimpedance spectroscopy), as an easy, non-invasive, portable bedside technique that is operator-independent for evaluating fat-free and fat mass compartments and their changes during treatment. Clinical examples of the determination of fat-free mass in healthy and ill individuals are also presented.     

Assessment of fat-free mass in teen-agers: use of TOBEC methodology

The accuracy of total-body electrical conductivity (TOBEC) for body composition assessment was examined in 50 teen-agers (33 males and 17 females) aged 11-19 y. Body composition measures included densitometry, hydrometry, bone mineral density of the one-third distal radius, and TOBEC. Fat-free mass (FFM) was calculated by using one-, two-, and three-compartment models: densitometry, FFMd; densitometry and hydrometry, FFMdw; and densitometry, hydrometry, and bone mineral density, FFMdwb. Correlations between TOBEC variables and the three calculations of FFM were highly significant (r = 0.88-0.95; P less than 0.01). No significant differences were observed (ANOVA) between the TOBEC estimate of FFM (FFMT) and FFMd, FFMdw, and FFMdwb. Similar results were observed when the data were analyzed by gender. The TOBEC estimate of FFM was equivalent to the estimates of FFM derived from one-, two-, and three-component models. Its ease of measurement and its prediction accuracy (R2 = 0.933; SEE = 2.45 kg) in teen-agers make it a preferred technique for body composition assessment.