生物电阻抗法测量肥胖者体脂含量的应用方程

生物电阻抗是近年来被广泛应用的一种快速、简便、安全测量体成分的方法。本研究采用水下称重测量 1 96名 (男性 :66名 ;女性 :1 30名 ) 1 8～ 67岁肥胖受试者的体脂含量 ,并用生物电阻抗方法测定生物电阻抗值。结果表明用水下称重法测量的体脂含量和去脂体重的测量结果与文献中不同国家生物电阻抗推算方程的推算结果有显著的统计学差异 (P <0 0 1 )。本文通过用多元线性逐步回归和方差分析方法建立了适合我国肥胖人群特点的体成分推算方程 :BF =0 846 Wt- 0 1 85 Ht2 z - 2 361 Sex - 2 4 977。Ht:身高(cm) ,Wt:体重 (kg) ,Z :生物电阻抗 (Ω) ,Sex :性别 (男性 =1 ,女性 =0 )。方程的相关系数 :r =0 92 3 ,标准误 :S x=3 43 ,方差分析 (ANOVA)具有统计学意义 (F =365 73 ,P <0 0 0 1 )。     

The Stayhealthy bioelectrical impedance analyzer predicts body fat in children and adults

Bioelectrical impedance analysis (BIA) is a time-efficient and cost-effective method for estimating body composition. We hypothesized that there would be no significant difference between the Stayhealthy BC1 BIA and the selected reference methods when determining body composition. Thus, the purpose of the present study was to determine the validity of estimating percent body fat (%BF) using the Stayhealthy BIA with its most recently updated algorithms compared to the reference methods of dual-energy x-ray absorptiometry for adults and hydrostatic weighing for children. We measured %BF in 245 adults aged 18 to 80 years and 115 children aged 10 to 17 years. Body fat by BIA was determined using a single 50 kHz frequency handheld impedance device and proprietary software. Agreement between BIA and reference methods was assessed by Bland and Altman plots. Bland and Altman analysis for men, women, and children revealed good agreement between the reference methods and BIA. There was no significant difference by t tests between mean %BF by BIA for men, women, or children when compared to the respective reference method. Significant correlation values between BIA, and reference methods for all men, women, and children were 0.85, 0.88, and 0.79, respectively. Reliability (test-retest) was assessed by intraclass correlation coefficient and coefficient of variation. Intraclass correlation coefficient values were greater than 0.99 (P < .001) for men, women, and children with coefficient of variation values 3.3%, 1.8%, and 1.7%, respectively. The Stayhealthy BIA device demonstrated good agreement between reference methods using Bland and Altman analyses.     

Prediction of fat-free mass and percentage of body fat in neonates using bioelectrical impedance analysis and anthropometric measures: validation against the PEA POD

Accurate assessment of neonatal body composition is essential to studies investigating neonatal nutrition or developmental origins of obesity. Bioelectrical impedance analysis or bioimpedance analysis is inexpensive, non-invasive and portable, and is widely used in adults for the assessment of body composition. There are currently no prediction algorithms using bioimpedance analysis in neonates that have been directly validated against measurements of fat-free mass (FFM). The aim of the study was to evaluate the use of bioimpedance analysis for the estimation of FFM and percentage of body fat over the first 4 months of life in healthy infants born at term, and to compare these with estimations based on anthropometric measurements (weight and length) and with skinfolds. The present study was an observational study in seventy-seven infants. Body fat content of infants was assessed at birth, 6 weeks, 3 and 4·5 months of age by air displacement plethysmography, using the PEA POD body composition system. Bioimpedance analysis was performed at the same time and the data were used to develop and test prediction equations for FFM. The combination of weight+sex+length predicted FFM, with a bias of < 100 g and limits of agreement of 6-13 %. Before 3 months of age, bioimpedance analysis did not improve the prediction of FFM or body fat. At 3 and 4·5 months, the inclusion of impedance in prediction algorithms resulted in small improvements in prediction of FFM, reducing the bias to < 50 g and limits of agreement to < 9 %. Skinfold measurements performed poorly at all ages.     

Total body water and percentage fat mass measurements using bioelectrical impedance analysis and anthropometry in spinal cord-injured patients

BACKGROUND AND AIMS: Spinal cord injured patients may be adversely affected by disturbances of nutritional status, particularly malnutrition and fat mass overload. Malnutrition increases the risk for development of pressure sores, and fat mass excess increases the cardiovascular and respiratory risks of these patients, as well as predisposing to the development of diabetes mellitus, pressures sores and bony fractures. Body impedance analysis and anthopometry are easy bedside methods for body composition assessment. The aims of the study were to validate, in 20 spinal cord injured patients, body impedance analysis as a means to estimate total body water, and to validate a skinfold measurement of percentage fat independent of hydration of fat-free mass in the same population. METHODS: Total body water was measured by (18)O dilution as a reference method. Impedance and anthropometric measurements (four different skinfolds) were obtained. The results of total body water given by impedance analysis and calculated with three formulas were compared to the reference method. The fat mass percentage obtained with each of the skinfolds using the 3-compartment Siri's formula was compared to a reference value using the sum of the skinfolds. RESULTS AND CONCLUSION: The formula using 100 kHz resistance, height, weight and gender overestimated total body water by only 0.76 +/- 1.85 L, with an acceptable concordance with labeled water results. The formula with 50 kHz resistance was less accurate and concordant. Each skinfold may be used for assessing percentage fat mass. Based on these findings, we feel that the triceps skinfold, whose the variability is the lowest compared to the reference values, can be used alone in clinical practice.     

Relationship among habitual tea consumption,percent body fat,and body fat distribution

OBJECTIVE: To disclose the possible relationship between habitual tea consumption and changes in total body fat and fat distribution in humans. RESEARCH METHODS AND PROCEDURES: A cross-sectional survey of 1,210 epidemiologically sampled adults (569 men and 641 women) were enrolled in our study. Tea consumption and other lifestyle characteristics were obtained by structured questionnaires. Percent body fat (BF%) was measured using bioelectrical impedance analysis. Body fat distribution was assessed using waist-to-hip ratio (WHR). RESULTS: Among the 1,103 analyzed subjects, 473 adults (42.9%) consumed tea once or more per week for at least 6 months. The habitual tea drinkers were male-dominant, more frequently current smokers, and alcohol or coffee drinkers than the nonhabitual tea drinkers. Habitual tea drinkers for more than 10 years showed a 19.6% reduction in BF% and a 2.1% reduction in WHR compared with nonhabitual tea drinkers. The multiple stepwise regression models revealed that men, older age, higher BMI, and current smokers were positive factors for BF% and WHR. In contrast, longer duration of habitual tea consumption and higher total physical activity were negative factors for BF%. Longer duration of habitual tea consumption, higher socioeconomic status, and premenopausal status were negative factors for WHR. DISCUSSION: An inverse relationship may exist among habitual tea consumption, BF%, and body fat distribution, especially for subjects who have maintained the habit of tea consumption for more than 10 years.     

One-year increment of fat mass and lean body mass of Japanese school children using bioelectrical impedance

Bioelectrical impedance analysis (BIA) and skinfold thickness (SF) (triceps and subscapular) methods were applied to 436 Japanese school children (228 boys and 208 girls) aged from 9 to 11 years with a one-year follow-up to determine changes in body composition. By BIA oneyear increment (Δ) of lean body mass (LBM) for boys increased significantly (p<0.01) and Δ LBM was almost equivalent to that for Δ weight (Wt). Δ Wt and Δ fat mass (FM) between the age 10 (from ages 10 to 11) and age 11 (from ages 11 to 12) groups in girls achieved statistical significance (p<0.01 and p<0.001, respectively) and Δ Wt was almost completely comprised of the Δ FM in these age groups. Δ FM in die age 11 group for girls was statistically higher than that in the age 10 group, and this obvious increase of FM in the age 11 group was presumed to be die effect of menses in consideration of die maximum oneyear increment of Ht (Δ Ht) in die age 10 group. These results of the assessment of body composition by BIA supported those of previous reports, and therefore BIA can be considered as a useful mediod to estimate changes in body composition of school children because it is simple and non-invasive and can be performed rapidly.     

Errors in estimating peritoneal fluid by bioelectrical impedance analysis and total body electrical conductivity.

Whole-body bioelectrical impedance analysis (BIA) and total body electrical conductivity (TOBEC) have been used to estimate body composition and generalized changes in total body water (TBW). The sensitivity of these methods to measure small, rapid, localized changes in body water has not been fully evaluated. We compared the prediction of TBW by whole-body and segmental BIA and TOBEC with deuterium oxide dilution (D2O) in 10 control subjects and 7 renal failure patients receiving continuous ambulatory peritoneal dialysis (CAPD) prior to and after dialysate infusion. Using D2O as the reference method, there was no significant mean residual error between TBW predicted by BIA and TOBEC in controls (?1.2 +/? 1.5 and ?0.9 +/? 1.0 kg) and CAPD patients pre-infusion (?1.0 +/? 2.0 and 0.29 +/? 2.01 kg). After infusing 1.9 +/? 0.18 kg dialysate, the mean residual error between change in body weight and the three methods was ?0.44 +/? 0.53 kg for D2O (p < 0.1), ?1.7 +/? 0.25 kg for BIA (p < 0.0001), and 1.2 +/? 0.4 kg for TOBEC (p < 0.001). Segmental BIA detected a 7.6% reduction in trunkal resistance with no significant change across the limbs, consistent with abdominal fluid accumulation. It is concluded that whole-body BIA underpredicts and TOBEC overpredicts small changes in peritoneal fluids.     

Estimation of total body water by bioelectrical impedance analysis

Total body water (TBW) measured by bioelectrical impedance analysis (BIA) was directly compared with deuterium-isotope dilution in a total of 58 subjects. First, sex-specific and group equations were developed by multiple regression analysis in (10 each) obese and nonobese men and women. Height/resistive impedance was the most significant variable used to predict deuterium-dilution space (D2O-TBW) and, combined with weight, yielded R = 0.99 and SE of estimate = 1.75 L. Equations predicted D2O-TBW equally well for obese and nonobese subjects. Second, the equations were prospectively tested in a heterogeneous group of 6 males and 12 females. Sex-specific equations predicted D2O-TBW with good correlation coefficients (0.96 and 0.93), total error (2.34 and 2.89 L), and a small difference between mean predicted and measured D2O-TBW (-1.4 +/- 2.05 and -0.48 +/- 2.83 L). BIA predicts D2O-TBW more accurately than weight, height, and/or age. A larger population is required to validate the applicability of our equations.     

人体成分分析及其应用

传统上使用体重指数(BMI)判断体型和营养状况具有其局限性.利用生物电阻抗法(BIA)人体成分分析技术可获得脂肪率、去脂体重指数等数据.我们认为,合适的脂肪率是男性12％ ～22％、女性20％ ～ 30％,中等的去脂体重指数是男性17.0～21.0、女性14.5 ～18.0.人体成分分析较BMI能更好地用于体型判断、营养评估、某些疾病的预后判断和调整用药剂量等.     

Predictive validity of four bioelectrical impedance equations in determining percent fat mass in overweight and obese children

Bioelectrical impedance equations are frequently used by food and nutrition professionals to estimate percent fat mass in overweight and obese children. However, it is not known whether they are accurate for such children, as they have been primarily developed for children of varying body weights. The aim of this cross-sectional study was to evaluate the predictive validity of four previously published prediction equations developed for the pediatric population, among a sample of overweight and obese children. Thirty overweight or obese children (mean age=7.57+/-1.28 years) underwent measurement of fat mass, percent fat mass, and fat-free mass using dual-energy x-ray absorptiometry (DEXA) and bioelectrical impedance analysis (BIA). Impedance values from the BIA were entered into the four prediction equations and Pearson correlations used to determine the significance of associations between each of the BIA prediction equations and DEXA for percent fat mass, fat mass, and fat-free mass. For percent fat mass, paired t tests were used to assess differences between the methods and the technique of Bland and Altman was used to determine bias and error. Results showed that the mean percent fat mass as determined by DEXA for this age group was 40.79%. In comparison with other BIA prediction equations, the Schaefer equation had the closest mean value of 41.98%, and was the only equation not to significantly differ from the DEXA (P=0.121). This study suggests that the Schaefer equation is the only accurate BIA prediction equation for assessing percent fat mass in this sample of overweight and obese children from primarily white backgrounds.     

一种阻抗法人体脂肪总量测量仪的研制及初步应用

本文介绍一种利用人体阻抗来测量人体脂肪总量的新仪器。它是根据当交流电信号通过人体时人体体内电阻与体内脂肪总量的相关性，将一标准电阻与被测人体串联，微型计算机系统通过比较交流电通过人体和标准电阻时所产生的电压降计算出人体体内的电阻值，然后结合被测者的身高、体重和年龄计算出入体的脂肪总量。本仪的准确性误差为３．２４％，重复性误差为２．７５％。     

Accuracy of body fat assessment by bioelectrical impedance in Japanese middle-aged and older people

Bioelectrical impedance analysis (BIA) is commonly used to measure the percentage of body fat (%BF), but its accuracy is controversial. In addition, the equations are specific to the group for which they were established. As far as we know, there is no study examining the accuracy of BIA in Japanese middle-aged and older people. We compared %BF assessed using BIA with that of dual-energy X-ray absorptiometry (DEXA) in 102 female and 51 male local residents aged 40 to 78 y. Simple correlation coefficients were 0.79 for females and 0.69 for males, which are statistically significant (p<0.001). However, BIA tended to overestimate %BF in the lower BF group and underestimate it in the BF higher group, and only 45.1% for female and 47.1% for male subjects were measured accurately, i.e., within 10% of the measurement by DEXA. This result suggests that this model of BIA is an alternative for estimating %BF in Japanese middle-aged and older people as well as when subjects are within a normal body fat range, but greater accuracy is needed for lean and overweight subjects.     

Effect of body positions and splints in bioelectrical impedance analysis.

The objective of this study was to evaluate body composition as measured by bioelectric impedance analysis using splints and body positions differing from the standard supine position. Forty-three patients, randomized into two groups of different body positions, and 101 healthy volunteers were prospectively studied. Resistance and reactance of body tissues were measured by bioelectric impedance analysis. Body composition is described by a three-compartment model composed of body fat, body cell mass, and extra cellular mass. The patients were measured in the standard supine position and then randomized into two groups. They were then remeasured with the appropriate splinting device or position change. Volunteers were measured in the standard supine position and all four alternative positions. There was a statistically significant difference demonstrated in whole body resistance, whole body reactance, body cell mass, and the ratio of extracellular mass to body cell mass in some body positions. The percentage of change with different body positions and splints, when compared with the standard supine position, was generally below 2%, a clinically insignificant difference. We conclude that the reliability of resistance and reactance as measured by bioelectric impedance analysis is clinically valid using any of the tested body positions and/or splints. The three-compartment model may be a useful concept to measure body composition changes in both healthy and sick persons.     

Evaluation of partial body composition using bioelectrical impedance in Japanese children

To clarify the growth pattern of body composition by body part for the management of childhood obesity, we measured body fat and muscle using BIA (bioelectrical impedance analysis) in 685 Japanese elementary schoolchildren (aged 6-11 years). The growth patterns of percentage body fat (%BF), fat mass (FM), and muscle mass (MM) were examined throughout the whole body and in various body parts. The %BF of the whole body was greater in females than in males, and this difference widened with age. The %BF, FM, and MM in each body part showed similar growth patterns and gender differences to those of the whole body. The mean %BF of the left limbs was higher than that of the right limbs at all age groups. BMI was strongly correlated with %BF in both sexes. In conclusion, the compositions of all body parts change similarly with age, and gender differences are also similar in childhood. The effect of one's dominant arm on body composition is seen at a young age. The accumulation of body composition data according to body part is indispensable for understanding childhood body composition and managing obesity.     

Associations of body mass index and percentage body fat by bioelectrical impedance analysis with cardiovascular risk factors in Japanese male office workers

To determine whether body mass index (BMI, kg/m2) or percentage body fat (%BF) by bioelectrical impedance analysis (BIA) better reflects the cardiovascular risk profile, we examined the associations among BMI, %BF by BIA, and cardiovascular risk factors (systolic blood pressure (SBP), diastolic blood pressure (SBP), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), LDL-C/HDL-C ratio, and triglycerides (TG)) in 1,217 Japanese male office workers aged 25 to 59 years. From stepwise regression analyses of cardiovascular risk factors on age, BMI, alcohol intake, and cigarette smoking, significant correlates were, in the order of relative importance: age, BMI, and alcohol intake for SBP and DBP (the cumulative percentage of variation; 14.9% and 21.3%, respectively); age, BMI, and alcohol intake (negative) for LDL-C (11.0%); BMI (negative), alcohol, and cigarette smoking (negative) for HDL-C (19.9%); BMI, alcohol intake (negative), age, and cigarette smoking for LDL-C/HDL-C ratio (23.1%); and BMI, age, cigarette smoking, and alcohol intake for Log TG (21.7%). From stepwise regression analyses using %BF by BIA as an independent factor, %BF by BIA was also significantly associated with each cardiovascular risk factor, but the decrease in explained variance for each cardiovascular risk factor was 0.2-4.5%, compared with the model using BMI as an independent factor. These results suggest that BMI may better reflect blood pressure or serum lipid profile than %BF by BIA.