PubMed Health⌕ Search

Biomedical subjects

Jack Wang

Publications and source records attributed to Jack Wang.

At least 19 recordsLinked to original sources
PubMed2006

Metabolically active portion of fat-free mass: a cellular body composition level modeling analysis.

The proportion of fat-free mass (FFM) as body cell mass (BCM) is highly related to whole body resting energy expenditure. However, the magnitude of BCM/FFM may have been underestimated in previous studies. This is because Moore's equation [BCM (kg) = 0.00833 x total body potassium (in mmol)], which was used to predict BCM, underestimates BCM by approximately 11%. The aims of the present study were to develop a theoretical BCM/FFM model at the cellular level and to explore the influences of sex, age, and adiposity on the BCM/FFM. Subjects were 112 adults who had the following measurements: total body water by (2)H(2)O or (3)H(2)O dilution; extracellular water by NaBr dilution; total body nitrogen by in vivo neutron activation analysis; and bone mineral by dual-energy X-ray absorptiometry. FFM was calculated using a multicomponent model and BCM as the difference between FFM and the sum of extracellular fluid and solids. The developed theoretical model revealed that the proportion of BCM to FFM is mainly determined by water distribution (i.e., E/I, the ratio of extracellular to intracellular water). A significant correlation (r = 0.90, P < 0.001) was present between measured and model-predicted BCM/FFM for all subjects pooled. Measured BCM/FFM [mean (SD)] was 0.584 +/- 0.041 and 0.529 +/- 0.041 for adult men and women (P < 0.001), respectively. A multiple linear regression model showed that there are independent significant associations of sex, age, and fat mass with BCM/FFM.

Adult↗
PubMed2006

Estrogen and exercise may be related to body fat distribution and leptin in young women.

OBJECTIVE: To evaluate the effects of estrogen deficiency and exercise on body composition and leptin in young women. DESIGN: Cross-sectional clinical study. SETTING: Volunteers in an academic research environment. PATIENT(S): Three age- and body mass index-matched groups: normal-weight women with exercise-associated amenorrhea, regularly menstruating exercising control women, and regularly menstruating normally active control women. INTERVENTION(S): Collection of blood samples and measurement of body fat and regional fat distribution by dual-energy x-ray absorptiometry. MAIN OUTCOME MEASURE(S): Central fat accumulation (i.e., ratio of trunk to extremity fat) and serum concentrations of E(2) and leptin. RESULT(S): In both regularly menstruating control groups, but not in the amenorrheic women, there was a negative correlation between the serum E(2) concentrations and the trunk-to-extremity fat ratio (r = -0.4), independent of age, exercise, body fat, and serum T concentrations. In all women, E(2) concentrations were positively and exercise inversely correlated to leptin concentrations, independent of body fat. CONCLUSION(S): Estradiol level is inversely associated with central fat accumulation only in women with regular menstrual cycles. In all young premenopausal subjects, estrogen secretion influences leptin concentrations independently of body fat.

Adipose Tissue↗
PubMed2006

Relationship of fat mass and serum estradiol with lower extremity bone in persons with chronic spinal cord injury.

In the spinal cord injury (SCI) population, a relationship between adiposity and leg bone has not been reported, nor one between serum estradiol and leg bone mass. A cross-sectional, comparative study of 10 male pairs of monozygotic twins discordant for SCI was performed. Relationships were determined among bone mineral density (BMD), bone mineral content (BMC), lean mass, fat mass, and serum sex steroids. In the twins with SCI, significant relationships were evident between leg BMD or BMC with total body percent fat (r2= 0.49, P < 0.05; r2= 0.45, P = 0.05), leg fat mass (r2 = 0.76, P < 0.0005; r2= 0.69, P = 0.005), and serum estradiol (r2= 0.40, P = 0.05; r2= 0.37, P = 0.05). By stepwise regression analysis, in the twins with SCI, leg fat mass was found to be the single most significant predictor of leg BMD or BMC (F = 12.01, r2= 0.76, P = 0.008; F = 50.87, r2= 0.86, P < 0.0001). In the able-bodied twins, leg lean mass correlated with leg BMD and BMC (r2= 0.58, P = 0.01; r2= 0.87, P = 0.0001). By use of within-pair differences, significant correlations were found for leg lean mass loss with leg BMD loss (r2= 0.56, P = 0.01) or leg BMC loss (r2= 0.64, P = 0.0005). In conclusion, in twins with SCI, significant correlations were observed between fat mass and leg BMD or BMC as well as between serum estradiol values and leg BMD. The magnitude of the leg muscle mass loss was correlated with the magnitude of bone loss.

Adipose Tissue↗
PubMed2006

Antagonists to human and mouse vascular endothelial growth factor receptor 2 generated by directed protein evolution in vitro.

Using directed in vitro protein evolution, we generated proteins that bound and antagonized the function of vascular endothelial growth factor receptor 2 (VEGFR2). Binders to human VEGFR2 (KDR) with 10-200 nM affinities were selected by using mRNA display from a library (10(13) variants) based on the tenth human fibronectin type III domain (10Fn3) scaffold. Subsequently, a single KDR binding clone (K(d) = 11 nM) was subjected to affinity maturation. This yielded improved KDR binding molecules with affinities ranging from 0.06 to 2 nM. Molecules with dual binding specificities (human/mouse) were also isolated by using both KDR and Flk-1 (mouse VEGFR2) as targets in selection. Proteins encoded by the selected clones bound VEGFR2-expressing cells and inhibited their VEGF-dependent proliferation. Our results demonstrate the potential of these inhibitors in the development of anti-angiogenesis therapeutics.

Amino Acid Sequence↗
PubMed2006

Serum iron and body fat distribution in a multiethnic cohort of adults living in New York City.

OBJECTIVE: To examine the relationship between serum iron and body composition in a multiracial adult cohort. METHODS: The analysis consisted of 670 participants on whom blood analysis and anthropometric data were available. The participants were recruited as part of the Rosetta Study (1990-2000), which was designed to assess body composition in a multiethnic cohort of healthy adults. Fasting iron level was measured as part of a biochemistry panel. Dual x-ray absorptiometry was used to assess fat mass. Anthropometric measures included waist circumference and body mass index (BMI; calculated as kg/m(2)) as an index of abdominal adiposity and overall body fatness, respectively. RESULTS: In the study cohort the mean age was 54+/-17 years and 60.9% were overweight or obese (BMI > or =25). Men had higher serum iron levels (94.91+/-34.52 microg/dL [16.99+/-6.18 micromol/L] vs 82.17+/-32.62 microg/dL [14.71+/-5.84 micromol/L]) and larger waist circumference (91.98+/-11.87 cm vs 85.24+/-12.37 cm) compared with women (P<0.001). Iron was inversely correlated with BMI (r=-0.23, P<0.001), waist circumference (r=-0.19, P<0.05), and fat mass (r=-0.19, P<0.05) among Hispanic women but not among African-American, white, or Asian women or in men of any race/ethnic group. CONCLUSIONS: The results of this study show an inverse association of measures of body fat distribution and total fat mass with serum iron level in Hispanic women. Studies designed to explore how micronutrients are used by the body at varying degrees of body fatness could provide useful information on the micronutrient-related comorbidities of obesity.

Abdominal Fat↗
PubMed2006

Sex difference in the effect of puberty on the relationship between fat mass and bone mass in 926 healthy subjects, 6 to 18 years old.

OBJECTIVE: Understanding factors influencing bone mineral accrual is critical to optimize peak bone mass during childhood. The epidemic of pediatric obesity and reported higher incident of fracture risk in obese children led us to study the influence of fat mass on bone mineral content (BMC) in children. RESEARCH METHODS AND PROCEDURES: Height; weight; pubertal stage; and BMC, non-bone fat-free mass (nbFFM), and fat mass (FM) by DXA were obtained in a multiethnic group of healthy children (444 girls/482 boys; 6 to 18 years old) recruited in the New York metropolitan area. Regression techniques were used to explore the relationship between BMC and FM, with age, height, nbFFM, pubertal stage, sex, and ethnicity as covariates. RESULTS: Because there were significant sex interactions, separate regression analyses were performed for girls and boys. Although ln(nbFFM) was the greatest predictor of ln(BMC), ln(FM) was also a significant predictor in prepubertal boys and all girls but not in pubertal boys. This effect was independent of ethnicity. DISCUSSION: FM was a determinant of BMC in all girls but in only prepubertal boys. Our study confirms nbFFM as the greatest predictor of BMC but is the first to find a sex difference in the effect of puberty on the relationship of FM to BMC. Our results suggest that, in two individuals of the same sex and weight, the one with greater fat mass will have lower BMC, especially pubertal boys. The implications of these findings for achievement of optimal peak bone mass in a pediatric population with an unprecedented incidence of overweight and "overfat" status remain to be seen.

Absorptiometry, Photon↗
PubMed2006

Serum magnesium and type-2 diabetes in African Americans and Hispanics: a New York cohort.

OBJECTIVES: The aim of this study was to examine the relationship of serum Mg with stage of diabetes measured by fasting serum glucose in a cohort of 485 African American and Hispanic adults. METHODS: The cross sectional Rosetta study was designed to assess body composition in a multi-racial cohort of healthy adults living in New York City. The data utilized for the current analyses were collected during the years 1990 to 2000. Serum Mg and glucose were measured after a 10-12 hour fast. Dual-energy x-ray absorptiometry was used to measure fat mass (FM) and fat free mass (FFM). RESULTS: The mean age of the cohort was 53 +/- 16 years. Hispanics had significantly lower (p < 0.05) mean serum Mg levels (0.82 +/- 0.07 mmol/L vs. 0.85 +/- 0.07 mmol/L) and FFM (48.8 +/- 10.9 kg vs. 50.9 +/- 10.3 kg) compared to African Americans. In both race/ethnic groups, individuals classified as having diabetes had significantly (p < 0.001) lower serum concentrations of Mg (0.80 +/- 0.07 mmol/L) compared to the normal group (0.84 +/- 0.07 mmol/L). CONCLUSIONS: These results show that in African American and Hispanic adults, those with diabetes have lower serum Mg levels compared to those classified as pre-diabetic or those with normal fasting glucose levels.

Adipose Tissue↗
PubMed2006

Validation of a 3-dimensional photonic scanner for the measurement of body volumes, dimensions, and percentage body fat.

BACKGROUND: The 3-dimensional photonic scan (3DPS) technique has been used during the past decade in the fashion industry and for epidemiologic surveys to estimate human body sizes. OBJECTIVE: The objective of the study was to validate the accuracy of a recently developed 3DPS (C9036-02; Hamamatsu Photonics KK, Hamamatsu, Japan) for the measurement of body volume, circumferences, lengths, and percentage body fat with the use of underwater weighing (UWW) and tape measures as criterion methods. DESIGN: Ninety-two subjects (44 females and 48 males) aged 6-83 y and weighing 23-182 kg (52-400 lbs) participated in the study. The subjects were measured while they wore minimal clothing and a head cap. Similar measurements were performed on a mannequin with and without clothing RESULTS: All subjects were measured with 3DPS and a tape measure; 63 subjects underwent UWW and residual lung volume measurements. The values obtained with 3DPS were slightly but significantly greater than those obtained with UWW for body volume (81.9 +/- 4.0 L compared with 81.5 +/- 4.0 L, P < 0.0001) and those obtained with a tape measure for circumferences (P < 0.001), but the values for percentage body fat were not significantly different between 3DPS and UWW (P = 0.648). The values obtained with 3DPS were significantly greater than those obtained by UWW and a tape measure for the clothed mannequin, but the values were not uniformly significantly different for the mannequin without clothing. CONCLUSIONS: The 3DPS measures body volume, circumferences, and length rapidly and accurately. However, to generate an accurate total-body volume measurement with 3DPS to estimate percentage body fat, the subjects must wear close-fitting minimal clothing and be able to stand motionless for 10 s (normal scan mode) while holding their breath, which is done immediately after a maximum expiration.

Adipose Tissue↗
PubMed2006

Total-body skeletal muscle mass: estimation by dual-energy X-ray absorptiometry in children and adolescents.

BACKGROUND: Skeletal muscle (SM) is an important compartment but is difficult to quantify in children and adolescents. OBJECTIVE: We investigated the potential of dual-energy X-ray absorptiometry (DXA) for measuring total-body SM in pediatric subjects. DESIGN: A previously published adult DXA SM prediction formula was evaluated in children and adolescents aged 5-17 y (n = 99) who varied in pubertal maturation stage. SM estimated by whole-body magnetic resonance imaging (MRI) was used as the reference. The adult SM model was not accurate for subjects below Tanner stage 5 (n = 65; aged 5-14 y). New pediatric SM prediction models were therefore developed and validated in a separate group (n = 18). RESULTS: The adult DXA SM prediction model was valid in subjects at Tanner stage 5 but significantly (P < 0.001) overestimated SM in subjects below Tanner stage 5. New SM prediction formulas were developed with appendicular lean soft tissue (ALST) estimates by DXA as the main predictor variable (eg, model 1, ALST alone: R(2) = 0.982, SEE = 0.565 kg, P < 0.001). The new models were validated by the leave-one-out method and were cross-validated in a separate validation group. CONCLUSIONS: A previously reported adult DXA SM prediction model is applicable in children and adolescents late in pubertal development (Tanner stage 5). A new DXA SM prediction model was developed for prepubertal and pubertal subjects (Tanner stage </=4) aged >/=5 y. DXA thus provides an important opportunity for quantifying total-body SM mass across most of the human life span.

Absorptiometry, Photon↗
PubMed2006

Total body protein mass: validation of total body potassium prediction model in children and adolescents.

Protein is an important body component for monitoring growth, development, and nutritional status. We previously developed a total body potassium (TBK, in mmol) and bone mineral (Mo, in kg) model for predicting total body protein (TBPro, in kg) in adults (TBPro = 0.00252 x TBK + 0.732 x Mo). However, the applicability of the TBK-Mo model for children is unknown. The study aims were to develop a TBK-independent 6-component (6-C) TBPro approach as the criterion, and then to validate the TBK-Mo model in children. The following measurements were made in adolescents and children (n = 62, 38 boys and 24 girls, aged 5-17 y): body weight (BW, in kg), body volume (BV, in liters) by air displacement plethysmography, total body water (TBW, in kg) by 2H2O dilution, Mo by dual-energy X-ray absorptiometry, and TBK by whole-body counting. A 6-C model was derived as TBPro = 2.922 x BW - 0.301 x TBW - 2.039 x Mo - 2.632 x BV. The TBPro estimates did not differ between the 6-C and TBK-Mo models (mean +/- SD, 0.20 +/- 0.86 kg). There was a significant correlation between TBPro by the 6-C and TBK-Mo models (r = 0.94, P < 0.001). Bland-Altman analysis indicated that the differences between TBPro by 6-C and TBK-Mo models were not significantly correlated with the mean TBPro estimates by the 2 models (r = 0.032, P > 0.05). The TBK-Mo model can thus be used to estimate TBPro in healthy adults, adolescents, and children > 5 y old.

Absorptiometry, Photon↗
PubMed2005

Antiretroviral therapy affects the composition of weight loss in HIV infection: implications for clinical nutrition.

BACKGROUND: Weight loss is comprised of variable proportions of fat and fat-free mass (FFM). HIV-infected patients treated with antiretroviral (ARV) agents may lose subcutaneous fat (lipoatrophy) in the absence of FFM depletion, which could confound the clinical interpretation of weight loss. METHODS: We retrospectively analyzed the results of anthropometric and dual-energy X-ray absorptiometry studies in 196 HIV-infected men and women with documented 10% weight loss (HIV group), and compared them to 29 untreated, HIV-infected men without 10% weight loss (HIV weight-stable), and 109 healthy adults (72 men and 37 women) to evaluate the effect of ARV therapy on the composition of weight loss. The HIV group was divided into four subgroups according to current ARV therapy: treatment-naive (59 men and 26 women), nucleoside reverse transcriptase inhibitor (NRTI) monotherapy (45 men), dual NRTI therapy (28 men) and highly active ARV therapy (HAART) (19 men and 20 women). RESULTS: Ages and heights were similar in all groups, while body mass index (BMI) and body composition differed significantly. BMI was higher in HIV-infected men and women on HAART than in the other HIV groups, although less than in HIV weight-stable (P=0.36) and healthy controls (P<0.0005). Fat content was lower in all HIV groups than in controls (P<0.001), while FFM was similar in HIV-infected men and women on dual NRTI and HAART and in controls. Comparison with HIV weight-stable gave higher estimates of the contribution of FFM to the differences in weight. CONCLUSION: Treatment of HIV infection with ARV may affect the interpretation of 10% weight loss.

Absorptiometry, Photon↗
PubMed2005

Korean and Caucasian overweight premenopausal women have different relationship of body mass index to percent body fat with age.

The aim of the study was to investigate in premenopausal women whether the relationship between percentage body fat (PBF) and body mass index (BMI; in kg/m2) differs between Korean Asians (Ko-As) living in Seoul, South Korea, and Caucasians (Ca) living in New York City. Healthy premenopausal women (50 Ko-As; 38 Ca), ages 22-50 yr, were studied. Weight, height, and PBF by dual-energy X-ray absorptiometry were measured. Total body dual-energy X-ray absorptiometry data were collected using GE-Lunar systems (Prodigy-Korea and DPXL-New York), and all scan analyses were performed by one technician in New York. Similar soft tissue phantoms were used for daily instrument calibrations at both sites. The relationship between PBF and BMI was assessed by multiple regression analysis with race, age, reciprocal of BMI (1/BMI), and a race-by-age interaction as the final independent variables. Race (P = 0.003) and 1/BMI (P < 0.001) were significantly related to PBF in this model. A significant race-by-age interaction (P = 0.039) indicated that the slope of the lines for PBF vs. age differed between Ko-As and Ca. This study demonstrates in a Ko-As sample that the BMI-fat relationship differs significantly from that in a comparable group of Caucasian women. Investigators who use BMI as an index of fatness should be aware of the well documented differences in the relationship of BMI and fatness across race/ethnic groups.

Adipose Tissue↗
PubMed2005

Extracellular water: greater expansion with age in African Americans.

Aging is associated with the onset of chronic diseases that lead to pathological expansion of the extracellular water (ECW) compartment. Healthy aging, in the absence of disease, is also reportedly accompanied by a relative expansion of the ECW compartment, although the studies on which this observation is based are few in number, applied different ECW measurement methods, included small ethnically homogeneous subject samples, and failed to adjust ECW for non-age-related influencing factors. The aim of the current study was to examine, in a large (n = 1,538) ethnically diverse [African American (AA), Asian, Caucasian, Hispanic] subject group the cross-sectional relationships between ECW and age after controlling first for other potential factors that may influence fluid distribution. ECW and intracellular water (ICW) were derived from measured total body water (isotope dilution) and potassium (40K whole body counting). The cross-sectional relationships between ECW, ICW, and ECW/ICW (E/I), and age were developed using multiple regression modelling methods. Body weight, weight squared, height, age, sex, race, and interactions were all significant ECW predictors. The slope of the observed race x age interaction was significantly greater in AA (beta = 0.0005, P = 0.005) than in the three other race groups. Race, sex, and age differences in fluid distribution persisted after adjusting for body composition in a subgroup (n = 994) with dual-energy X-ray absorptiometry lean soft tissue and fat measurements. A relative ECW expansion (i.e., E/I) was present with greater age in most sex-race groups, although the effect was not significantly larger in AA males (P > 0.05) compared with the other race groups, except Asians (P < 0.05). For females, a larger E/I-age effect was found in AA compared with the other race groups, but only the comparison against Hispanics was significant (P < 0.05). The ECW compartment and E/I are thus variably larger, according to race, in healthy older subjects independent of sex, lean soft tissue, and fat mass.

Black or African American↗
PubMed2005

Body composition and metabolic changes in antiretroviral-naive patients randomized to didanosine and stavudine vs. abacavir and lamivudine.

Comparisons of body composition and metabolic changes among antiretroviral-naive patients randomly assigned to didanosine and stavudine- (ddI+d4T) vs. abacavir and lamivudine- (ABC+3TC) containing regimens were assessed in a nested substudy of an ongoing multicenter randomized trial. At baseline and every 4 months, body cell mass and total body fat were calculated, anthropometric measurements were performed, and fasting metabolic parameters were obtained. The rates of change (unit/mo) estimated using the slopes of regression lines and overall mean changes from baseline were compared by study assignment. Among 96 patients enrolled, 46 received ddI+d4T- and 50 received ABC+3TC-containing regimens with a median follow-up of 32.4 months. For both study arms, an overall increase in the rates of change was seen for body cell mass. For ddI+d4T, after an initial increase, the rates of change declined for regional fat and total body fat compared with an increase for ABC+3TC, with the 2 arms being significantly different (P<0.05). For high-density lipoprotein cholesterol rates of change, ddI+d4T decreased, while ABC+3TC increased. For both arms, low-density lipoprotein cholesterol decreased, while triglycerides increased. Early and sustained increases in insulin and insulin resistance were seen only for ddI+d4T. In this prospective study, metabolic and body composition changes varied according to whether subjects received ddI+d4T or ABC+3TC.

Adult↗
PubMed2005

Air displacement plethysmography: validation in overweight and obese subjects.

OBJECTIVE: Patients with moderate and severe obesity, because of their physical size, often cannot be evaluated with conventional body composition measurement systems. The BOD POD air displacement plethysmography (ADP) system can accommodate a large body volume and may provide an opportunity for measuring body density (D(b)) in obese subjects. D(b) can be used in two- or three-compartment body composition models for estimating total body fat in patients with severe obesity. The purpose of this study was to compare D(b) measured by ADP to D(b) measured by underwater weighing (UWW) in subjects ranging from normal weight to severely obese. RESEARCH METHODS AND PROCEDURES: D(b) was measured with UWW and BOD POD in 123 subjects (89 men and 34 women; age, 46.5 +/- 16.9 years; BMI, 31.5 +/- 7.3 kg/m2); 15, 70, and 10 subjects were overweight (25 < or = BMI < 30 kg/m2), obese (30 < or = BMI < 40 kg/m2), and severely obese (BMI > or = 40 kg/m2), respectively. RESULTS: There was a strong correlation between D(b) (kilograms per liter) measured by UWW and ADP (r = 0.94, standard error of the estimate = 0.0073 kg/L, p < 0.001). Similarly, percent fat estimates from UWW and ADP using the two-compartment Siri equation were highly correlated (r = 0.94, standard error of the estimate = 3.58%, p < 0.001). Bland-Altman analysis showed no significant bias between D(b) measured by UWW and ADP. After controlling for D(b) measured by ADP, no additional between-subject variation in D(b) by UWW was accounted for by subject age, sex, or BMI. DISCUSSION: Body density, an important physical property used in human body composition models, can be accurately measured by ADP in overweight and obese subjects.

Adipose Tissue↗
PubMed2005

Four-compartment cellular level body composition model: comparison of two approaches.

OBJECTIVE: The aim of this study was to develop and compare two DXA-based four-compartment [body weight=body cell mass (BCM)+extracellular fluid (ECF)+extracellular solids (ECS)+fat] cellular level models. RESEARCH METHODS AND PROCEDURES: Total body potassium (TBK) model: BCM from TBK by whole-body counting-ECF(TBK)=LST-[BCM(TBK)+0.73 x osseous mineral (Mo)]. Bromide model: ECF from sodium bromide dilution-BCM(BROMIDE)=LST-(ECF(BROMIDE)+0.73xMo); Mo and LST measurements came from DXA. The two approaches were evaluated in 99 healthy men and 118 women. RESULTS: BCM estimates were highly correlated (r=0.97, p<0.001), as were ECF estimates (r=0.87, p<0.001); a small statistically significant mean difference was present (mean+/-SD; BCM(TBK) model, 30.4+/-8.9 kg; BCM(BROMIDE), 31.4+/-9.3 kg; Delta=1.0+/-2.8 kg; p<0.001; ECF(TBK), 18.5+/-4.2 kg; ECF(BROMIDE), 17.5+/-3.6 kg; Delta=1.0+/-2.8 kg; p<0.001). A high correlation (r=0.97, p<0.001) and good agreement (38.9+/-9.5 vs. 38.9+/-9.5 kg; Delta=0.0+/-2.4 kg; p=0.39) were present between TBW, derived as the sum of intracellular water from TBK and ECW from bromide, and measured TBW by 2H2O dilution. DISCUSSION: Two developed four-compartment cellular level DXA models, one of which is appropriate for use in most clinical and research settings, provide comparable results and are applicable for BCM and ECF estimation of subject groups with hydration disturbances.

Absorptiometry, Photon↗
PubMed2005

Bioelectrical impedance analysis: population reference values for phase angle by age and sex.

BACKGROUND: Phase angle is an indicator based on reactance and resistance obtained from bioelectrical impedance analysis (BIA). Although its biological meaning is still not clear, phase angle appears to have an important prognostic role. OBJECTIVE: The aim of this study was to estimate population averages and SDs of phase angle that can be used as reference values. DESIGN: BIA and other methods used to evaluate body composition, including hydrodensitometry and total body water, were completed in 1967 healthy adults aged 18-94 y. Phase angle was calculated directly from body resistance and reactance, and fat mass (FM) was estimated from the combination of weight, hydrodensitometry, and total body water by using the 3-compartment Siri equation. Phase angle values were compared across categories of sex, age, body mass index (BMI), and percentage FM. RESULTS: Phase angle was significantly (P < 0.001) smaller in women than in men and was lower with greater age (P < 0.001). Phase angle increased with an increase in BMI and was significantly inversely associated with percentage fat in men. Phase angle was significantly predicted from sex, age, BMI, and percentage FM in multiple regression models. CONCLUSIONS: Phase angle differs across categories of sex, age, BMI, and percentage fat. These reference values can serve as a basis for phase angle evaluations in the clinical setting.

Adult↗