Biomedical subjects

Steven B Heymsfield

Publications and source records attributed to Steven B Heymsfield.

At least 37 records · Page 2Linked to original sources

PubMed2005

A cellular-level approach to predicting resting energy expenditure across the adult years.

BACKGROUND: We previously derived a whole-body resting energy expenditure (REE) prediction model by using organ and tissue mass measured by magnetic resonance imaging combined with assumed stable, specific resting metabolic rates of individual organs and tissues. Although the model predicted REE well in young persons, it overpredicted REE by approximately 11% in elderly adults. This overprediction may occur because of a decline in the fraction of organs and tissues as cell mass with aging. OBJECTIVE: The aim of the present study was to develop a cellular-level REE prediction model that would be applicable across the adult age span. Specifically, we tested the hypothesis that REE can be predicted from a combination of organ and tissue mass, the specific resting metabolic rates of individual organs and tissues, and the cellular fraction of fat-free mass. DESIGN: Fifty-four healthy subjects aged 23-88 y had REE, organ and tissue mass, body cell mass, and fat-free mass measured by indirect calorimetry, magnetic resonance imaging, whole-body (40)K counting, and dual-energy X-ray absoptiometry, respectively. RESULTS: REE predicted by the cellular-level model was highly correlated with measured REE (r = 0.92, P < 0.001). The mean difference between measured REE (x+/- SD: 1487 +/- 294 kcal/d) and predicted REE (1501 +/- 300 kcal/d) for the whole group was not significant, and the difference between predicted and measured REE was not associated with age (r = 0.009, NS). CONCLUSION: The present approach establishes an REE-body composition link with the use of a model at the cellular level. The combination of 2 aging-related factors (ie, decline in both the mass and the cellular fraction of organs and tissues) may account for the lower REE observed in elderly adults.

Absorptiometry, Photon↗

PubMed2005

Adipose tissue in muscle: a novel depot similar in size to visceral adipose tissue.

BACKGROUND: The manner in which fat depot volumes and distributions, particularly the adipose tissue (AT) between the muscles, vary by race is unknown. OBJECTIVE: The objective was to quantify a previously unstudied and novel intermuscular AT (IMAT) depot and subcutaneous AT, visceral AT (VAT), and total-body skeletal muscle mass in healthy sedentary African American (AA), Asian, and white adults by whole-body magnetic resonance imaging. IMAT is the AT between muscles and within the boundary of the muscle fascia. DESIGN: Analyses were conducted on 227 women [AA (n = 79): body mass index (BMI; in kg/m(2)), 29.0 +/- 5.5; age, 45.7 +/- 16.9 y; Asian (n = 38): BMI, 21.7 +/- 2.9; age, 47.2 +/- 19.9 y; whites (n = 110): BMI, 24.9 +/- 5.4; age, 43.7 +/- 16.2 y]) and 111 men [AA (n = 39): BMI, 25.6 +/- 3.2; age, 45.5 +/- 18.8 y; Asian (n = 13): BMI, 24.9 +/- 2.5; age, 45.6 +/- 25.0 y; white (n = 59): BMI, 25.8 +/- 3.8; age 44.5 +/- 16.3 y]. RESULTS: IMAT depots were not significantly different in size between race groups at low levels of adiposity; however, with increasing adiposity, AAs had a significantly greater increment in the proportion of total AT (TAT) than did the whites and Asians (58, 46, and 44 g IMAT/kg TAT, respectively; P = 0.001). VAT depots were not significantly different in size at low levels of adiposity but, with increasing adiposity, VAT accumulation was greater than IMAT accumulation in the Asians and whites; no significant differences were observed in AAs. CONCLUSION: Race differences in AT distribution extend to IMAT, a depot that may influence race-ethnicity differences in dysglycemia.

Adipose Tissue↗

PubMed2005

QDR 4500A dual-energy X-ray absorptiometer underestimates fat mass in comparison with criterion methods in adults.

BACKGROUND: Dual-energy X-ray absorptiometry (DXA) has become one of the most frequently used methods for estimating human body composition. Although the DXA technique has been validated for the measurement of fat-free mass and fat mass, differences in calibration between instruments produced by different manufacturers, as well as between different models produced by the same manufacturer, have been reported. OBJECTIVE: The objective was to compare the calibration of the QDR 4500A against criterion methods in a large heterogeneous population. DESIGN: DXA-derived body-composition data were obtained from 7 studies: 6 data sets were provided by the investigators, one of which was published. The data included fat mass and fat-free mass measured with a QDR 4500A and criteria measurements of body composition from total body water by dilution at 4 centers, densitometry from 1 center, and four-compartment analysis at 2 centers. RESULTS: In the cohort of 1195 subjects, 602 men and 593 women aged 19-82 y with a body mass index (in kg/m2) of 16-44, the fan-beam DXA overestimated fat-free mass (P < 0.05). A significant difference was observed in all 7 data sets, and the mean (+/-SE) was 5 +/- 1%. CONCLUSIONS: It is recommended that the lean soft tissue mass estimate with the fan-beam QDR 4500A be reduced by 5% and that for fat mass be increased by that same mass. This finding is particularly important because the National Health and Nutrition Examination Survey is using the QDR 4500A to assess body composition in a nationally representative sample of persons in the United States.

Absorptiometry, Photon↗

PubMed2005

Body fat redistribution after weight gain in women with anorexia nervosa.

BACKGROUND: Body image distortions are a core feature of anorexia nervosa (AN). Increasing evidence suggests that the fat distribution immediately after weight restoration in patients with AN differs from the distribution typical of healthy adult women. OBJECTIVE: The purpose of this study was to assess body fat distribution before and shortly after normalization of weight in women with AN. DESIGN: Body composition and fat distribution were assessed by anthropometry, dual-energy X-ray absorptiometry, and whole-body magnetic resonance imaging in 29 women with AN before and after weight normalization and at a single time point in 15 female control subjects. Hormone concentrations were also evaluated in patients and control subjects. RESULTS: During approximately 10.1 +/- 2.9 wk (range: 4-17.3 wk) of treatment, patients with AN gained 12.2 +/- 3.6 kg, and refed weight (54.1 +/- 4.2 kg) did not differ significantly from that of control subjects (54.7 +/- 4.4 kg). Waist-to-hip circumference ratio (P < 0.006), total trunk fat (P < 0.003), visceral adipose tissue (P < 0.006), and intramuscular adipose tissue (P < 0.003) were significantly greater in the weight-recovered patients than in the control subjects. In contrast, after refeeding, total subcutaneous adipose tissue and skeletal muscle mass did not differ significantly between the patients and control subjects. In patients with AN, serum cortisol decreased and serum estradiol increased significantly with refeeding but not to control concentrations. CONCLUSIONS: In women with AN, normalization of weight in the short term is associated with an abnormal distribution of body fat. The implications of these findings for the long-term psychological and physical health of women with AN are unknown.

Absorptiometry, Photon↗

PubMed2005

Waist circumference and abdominal adipose tissue distribution: influence of age and sex.

BACKGROUND: The influence of age and sex on the distribution of abdominal adipose tissue for a given waist circumference (WC) is unclear. OBJECTIVE: The objective was to investigate the influence of age and sex on total (TAAT), visceral (VAT), and abdominal subcutaneous (ASAT) adipose tissue for a given WC. DESIGN: Body composition was assessed by whole-body magnetic resonance imaging in 147 younger men (< 50 y), 83 older men, 171 younger (premenopausal) women, and 80 older (postmenopausal) women with a wide range (16-40; in kg/m(2)) of body mass indexes. RESULTS: Within each sex, the regression lines between WC and TAAT were not significantly different (P > 0.1) between younger and older groups. Collapsed across age groups, women had more TAAT for a given WC than did men; however, this difference was significantly reduced with increasing WC (P < 0.05). Within each sex, regression lines derived for WC and ASAT were not significantly different between younger and older groups (P > 0.1). Collapsed across age groups, women had 1.8 kg more ASAT for a given WC (P < 0.05) than did men across the range of WCs. Within each sex, older men and women had a significantly greater increase in VAT for a given WC (P < 0.05) than did younger men and women. Furthermore, independent of age group, the slopes for WC and VAT were significantly higher (P < 0.05) in men than in women. CONCLUSIONS: There are significant sex differences in TAAT, VAT, and ASAT for a given WC. Furthermore, the relation between WC and VAT is substantially influenced by age.

Abdomen↗

PubMed2005

Estimation of total-body and limb muscle mass in hemodialysis patients by using multifrequency bioimpedance spectroscopy.

BACKGROUND: Skeletal muscle mass can be measured noninvasively with magnetic resonance imaging (MRI), but this is time-consuming and expensive. OBJECTIVE: We evaluated the use of multifrequency bioimpedance spectroscopy (BIS) measurements of intracellular volume (ICV) to model total-body skeletal muscle mass (TBMM) and limb skeletal muscle mass in hemodialysis patients. DESIGN: TBMM was measured by MRI in 20 male and 18 female hemodialysis patients with a median (range) age of 54 y (33-73 y), weight of 78.9 kg (43.2-120 kg), and body mass index (BMI; in kg/m2) of 27.3 (19.4-46.6). We measured total body water (TBW) by using D2O dilution, extracellular volume (ECV) as bromide space, and ICV as TBW minus bromide space. Total body potassium (TBK) measured as 40K was used as an independent model of TBMM. BIS was used to measure whole-body TBW (ankle to wrist) and TBW in the arms and legs. BIS-estimated ICV was used to construct models to calculate limb muscle mass and TBMM. The latter was compared with models derived from isotopic methods. RESULTS: BIS yielded a model for TBMM [TBMM = 9.52 + 0.331 x ICV + 2.77 (male) + 0.180 x weight (kg) - 0.133 x age] (R2 = 0.937, P < 0.0001) as precise as TBK-measured TBMM [TBMM = 1.29 + 0.00453 x TBK (mEq) + 1.46 (male) + 0.144 x weight (kg) - 0.0565 x age] (R2 = 0.930, P < 0.0001) or isotopic methods. BIS models were also developed for measuring leg and arm muscle mass. CONCLUSION: BIS provides an estimate of TBMM that correlates well with isotopic methods in approximating values obtained by MRI and can be used to estimate limb muscle mass.

Adult↗

PubMed2005

Human cortical specialization for food: a functional magnetic resonance imaging investigation.

Although specialized cortical pathways that process specific sensory stimuli and/or execute cognitive functions have been identified, the neuro-specificity for food-related stimuli has not been clearly demonstrated. We employed functional magnetic resonance imaging (fMRI) to compare neural systems associated with the appreciation of foods and nonfoods. Healthy, normal weight, right-handed men and women (n = 12; age 29.8 +/- 1.8 y, BMI 21.8 +/- 0.8 kg/m(2)) were imaged by fMRI while fasting. Real food and nonfood items were presented to subjects both visually and tactilely, during scanning. Subjects were instructed to pay attention to the items. A randomized 2 x 2 block design consisted of 4 conditions: visual food, visual nonfood, tactile food, and tactile nonfood. Brain regions that were significantly activated to a greater extent during the presentation of foods compared with nonfood items included the anterior cingulate, superior temporal gyrus, parahippocampal gyrus, hippocampus, and the insula. These findings support the claim that the presence of food (either seen or felt) elicits a unique cortical response that is differentiated from nonfood items. This neural substrate specialized for processing of foods informs models of food-related behavior.

Adult↗

PubMed2005

Inadequate sleep as a risk factor for obesity: analyses of the NHANES I.

STUDY OBJECTIVES: Sleep deprivation has been hypothesized to contribute toward obesity by decreasing leptin, increasing ghrelin, and compromising insulin sensitivity. This study examines cross-sectional and longitudinal data from a large United States sample to determine whether sleep duration is associated with obesity and weight gain. DESIGN: Longitudinal analyses of the 1982-1984, 1987, and 1992 NHANES I Followup Studies and cross-sectional analysis of the 1982-1984 study. SETTING: Probability sample of the civilian noninstitutionalized population of the United States. PARTICIPANTS: Sample sizes of 9,588 for the cross-sectional analyses, 8,073 for the 1987, and 6,981 for the 1992 longitudinal analyses. MEASUREMENTS AND RESULTS: Measured weight in 1982-1984 and self-reported weights in 1987 and 1992. Subjects between the ages of 32 and 49 years with self-reported sleep durations at baseline less than 7 hours had higher average body mass indexes and were more likely to be obese than subjects with sleep durations of 7 hours. Sleep durations over 7 hours were not consistently associated with either an increased or decreased likelihood of obesity in the cross-sectional and longitudinal results. Each additional hour of sleep at baseline was negatively associated with change in body mass index over the follow-up period, but this association was small and statistically insignificant. CONCLUSIONS: These findings support the hypothesis that sleep duration is associated with obesity in a large longitudinally monitored United States sample. These observations support earlier experimental sleep studies and provide a basis for future studies on weight control interventions that increase the quantity and quality of sleep.

Adult↗

PubMed2005

The end of body composition methodology research?

PURPOSE OF REVIEW: Over one century of research has led to methods for measuring all major body components at the atomic, molecular, cellular, and tissue-system levels. These remarkable developments have fueled a rapid and sustained increase in 'body composition' biological findings and related publications. Other than small, incremental improvements in available methods, is there no longer a need for developing new body composition methods? This review examines the question: are we approaching the 'end' of body composition methodology research? RECENT FINDINGS: Emerging and rapidly growing areas outside of 'traditional' body composition research are highlighting the need for new and innovative method development. Recently introduced technologies such as positron emission tomography and functional magnetic resonance imaging extend 'mass' estimates to corresponding 'function' and physiology in humans. Although all major components are now measurable in humans, large gaps remain when considering factors such as radiation exposure, invasiveness, static versus dynamic measurements, and laboratory versus clinic and field assessments. SUMMARY: The end of the first phase of body composition method development has now arrived: all major components are measurable in vivo. The accessibility of these methods is stimulating rapid advances in biological knowledge surrounding human body composition from in utero to old age. Sustaining advances in new body composition method development will require extending the boundaries of the field as it now exists.

Biomedical Research↗

PubMed2005

Four commonly used dual-energy X-ray absorptiometry scanners do not identically classify subjects for osteopenia or osteoporosis by T-score in four bone regions BIz11.5.

We investigated whether four commonly used dual-energy X-ray absorptiometry (DXA) scanners (DPX, DPX-L,and Prodigy by GE Lunar, and Delphi-A by Hologic) could classify identical subjects as osteopenic or osteoporotic using the T-score for bone mineral density in four regions of interest: PA spine (L1-L4), femur (total), forearm (total),and 33% radius in 77 adults (38 females) free of treatment for bone metabolic disease (age range 20-81 yr). There were no significant differences between T-score means for posterior-anterior spine by DPX, DPX-L, and Prodigy, but they were higher than the mean T-score by Delphi-A (p < 0.05). Prodigy gave the lowest and DPX and Delphi-A gave the highest T-score for 33% radius (p < 0.05). No subject was classified as osteoporotic in the femur region by the four scanners, although other classifications varied by region and scanner. No two scanners classified subjects identically for osteopenia in any of the four regions. These results indicate that classification of bone density in individual subjects using T-scores varies by different DXA scanners, even the scanners were made by the same manufacturer.

Absorptiometry, Photon↗

PubMed2005

Reproducibility of pediatric whole body bone and body composition measures by dual-energy X-ray absorptiometry using the GE Lunar Prodigy.

The use of dual-energy X-ray absorptiometry (DXA) in pediatrics is increasing. It is safe, readily available, and easily performed, but there is little information on reproducibility. The aim of this study is to evaluate the reproducibility of whole body DXA scans in children. Total and regional bone mineral density, bone mineral content, nonbone, lean fat mass, and percent fat were measured twice by whole body DXA (GE Lunar Prodigy) in 49 subjects (5 to 17 yr). Within each subject, between subjects, and reading standard deviations for each body component were evaluated as well as intraclass correlations (IC) and coefficients of variation (CV). Total body measurements had better IC and CV than regional results from the whole body scan, with legs and arms better than trunk and spine. IC values were >or=0.989 for total body, >or=0.976 for legs and arms, and >or=0.875 for trunk and spine. CV values ranged 0.18 to 1.97% for total body, and 0.96 to 6.91% for regional measures. These values confirm that body composition and bone mass by DXA are highly reproducible among pediatric subjects. The results of this study can be used by clinicians and researchers for interpretation of longitudinal observations and for power calculations.

Absorptiometry, Photon↗

PubMed2005

Pediatric obesity phenotyping by magnetic resonance methods.

PURPOSE OF REVIEW: Accurate measurement of adiposity in obese children is required for characterizing the condition's phenotype, severity, and treatment effects in vivo. Non-invasive and safe, magnetic resonance imaging and spectroscopy provide an important new approach for characterizing key aspects of pediatric obesity. This review focuses on recent advances in non-invasive magnetic resonance imaging and spectroscopy for quantifying total body and regional adiposity, mapping adipose tissue distribution, and evaluating selected metabolic disturbances in children. The aim is to provide an investigator-focused overview of magnetic resonance methods for use in the study of pediatric body composition and metabolism. RECENT FINDINGS: Whole body axial images can be rapidly acquired on most clinical magnetic resonance imaging scanners. The images can then be semi-automatically segmented into subcutaneous, visceral, and intramuscular adipose tissue. Specific pediatric studies of errors related to slice gap and number are available. The acquisition of scans in healthy and premature infants is now feasible with recent technological advances. Spectroscopic, Dixon, and other approaches can be used to quantify the lipid content of liver, skeletal muscle, and other organs. Protocol selection is based on factors such as subject age and cost. Particular attention should be directed towards identification of landmarks in growth studies. Recent advances promise to reduce the requirement of subjects to remain motionless for relatively long periods. SUMMARY: Magnetic resonance imaging and spectroscopy are safe, practical, and widely available methods for phenotyping adiposity in children that open new opportunities for metabolism and nutritional research.

Adipose Tissue↗

PubMed2004

Total body skeletal muscle and adipose tissue volumes: estimation from a single abdominal cross-sectional image.

A single abdominal cross-sectional computerized axial tomography and magnetic resonance image is often obtained in studies examining adipose tissue (AT) distribution. An abdominal image might also provide additional useful information on total body skeletal muscle (SM) and AT volumes with related physiological insights. We therefore investigated the relationships between abdominal SM and AT areas from single images and total body component volumes in a large and diverse sample of healthy adult subjects. Total body SM and AT volumes were derived by whole body multislice magnetic resonance imaging in 123 men [age (mean +/- SD) of 41.6 +/- 15.8 yr; body mass index of 25.9 +/- 3.4 kg/m(2)] and 205 women (age of 47.8 +/- 18.7 yr; body mass index of 26.7 +/- 5.6 kg/m(2)). Single abdominal SM and AT slice areas were highly correlated with total body SM (r = 0.71-0.92; r = 0.90 at L(4)-L(5) intervertebral space) and AT (r = 0.84-0.96; r = 0.94 at L(4)-L(5) intervertebral space) volumes, respectively. R(2) increased by only 5.7-6.1% for SM and 2.7-4.4% for AT with the inclusion of subject sex, age, ethnicity, scanning position, body mass index, and waist circumference in the model. The developed SM and AT models were validated in an additional 49 subjects. To achieve equivalent power to a study measuring total body SM or AT volumes, a study using a single abdominal image would require 17-24% more subjects for SM and 6-12% more subjects for AT. Measurement of a single abdominal image can thus provide estimates of total body SM and AT for group studies of healthy adults.

Abdomen↗

PubMed2004

Dual-energy X-ray absorptiometry lean soft tissue hydration: independent contributions of intra- and extracellular water.

Dual-energy X-ray absorptiometry (DEXA) provides a measure of lean soft tissue (LST). LST hydration, often assumed to be constant, is relevant to several aspects of DEXA body composition estimates. The aims of this study were to develop a theoretical model of LST total body water (TBW) content and to examine hydration effects with empirically derived model coefficients and then to experimentally test the model's prediction that, in healthy adults, LST hydration is not constant but varies as a function of extra- and intracellular water distribution (E/I). The initial phase involved TBW/LST model development and application with empirically derived model coefficients. Model predictions were then tested in a cross-sectional study of 215 healthy adults. LST was measured by DEXA, extracellular water (ECW) by NaBr dilution, intracellular water (ICW) by whole body (40)K counting, and TBW by (2)H(2)O dilution. TBW estimates, calculated as ECW + ICW, were highly correlated with (r = 0.97, SEE = 2.1 kg, P < 0.001) and showed no significant bias compared with TBW measured by (2)H(2)O. Model-predicted TBW/LST was almost identical to experimentally derived values (means +/- SD) in the total group (0.767 vs. 0.764 +/- 0.028). LST hydration was significantly correlated with E/I (total group, r = 0.30, SEE = 0.027, P < 0.001). Although E/I increased with age (men, r = 0.48; women, r = 0.37; both P < 0.001), the association between TBW/LST and age was nonsignificant. Hydration of the DEXA-derived LST compartment is thus not constant but varies predictably with ECW and ICW distribution. This observation has implications for the accuracy of body fat measurements by DEXA and the use of TBW as a means of checking DEXA system calibration.

Absorptiometry, Photon↗

PubMed2004

Three-compartment model: critical evaluation based on neutron activation analysis.

There is renewed interest in Siri's classic three-compartment (3C) body composition model, requiring body volume (BV) and total body water (TBW) estimates, because dual-energy X-ray absorptiometry (DEXA) and in vivo neutron activation (IVNA) systems cannot accommodate subjects with severe obesity. However, the 3C model assumption of a constant ratio (alpha) of mineral (M) to total body protein (TBPro) and related residual mass density (D(RES)) based on cadaver analyses might not be valid across groups differing in sex, race, age, and weight. The aim of this study was to derive new 3C model coefficients in vivo and to compare these estimates to those derived by Siri. Healthy adults (n = 323) were evaluated with IVNA and DEXA and the measured components used to derive alpha and D(RES). For all subjects combined, values of alpha and D(RES) (means +/- SD, 0.351 +/- 0.043; 1.565 +/- 0.023 kg/l) were similar to Siri's proposed values of 0.35 and 1.565 kg/l, respectively. However, alpha and D(RES) varied significantly as a function of sex, race, weight, and age. Expected errors in percent body fat arising by application of Siri's model were illustrated in a second group of 264 adults, including some whose size exceeded DEXA limits but whose BV and TBW had been measured by hydrodensitometry and (2)H(2)O dilution, respectively. Extrapolation of predictions by newly developed models to very high weights allows percent fat error estimation when Siri's model is applied in morbidly obese subjects. The present study results provide a critical evaluation of potential errors in the classic 3C model and present new formulas for use in selected populations.

Absorptiometry, Photon↗

PubMed2004

Intermuscular adipose tissue-free skeletal muscle mass: estimation by dual-energy X-ray absorptiometry in adults.

Skeletal muscle (SM) is a large and physiologically important compartment. Adipose tissue is found interspersed between and within SM groups and is referred to as intermuscular adipose tissue (IMAT). The study objective was to develop prediction models linking appendicular lean soft tissue (ALST) estimates by dual-energy X-ray absorptiometry (DXA) with whole body IMAT-free SM quantified by magnetic resonance imaging. ALST and total-body IMAT-free SM were evaluated in 270 healthy adults [body mass index (BMI) of <35 kg/m(2)]. The SM prediction models were then validated by the leave-one-out method and by application in a new group of subjects who varied in SM mass [anorexia nervosa (AN), n = 23; recreational athletes, n = 16; patients with acromegaly, n = 7]. ALST alone was highly correlated with whole body IMAT-free SM [model 1: R(2) = 0.96, standard error (SE) = 1.46 kg, P < 0.001]; age (model 2: R(2) = 0.97, SE = 1.38 kg, P < 0.001) and sex and race (model 3: R(2) = 0.97, SE = 1.06 kg, both P < 0.001) added significantly to the prediction models. All three models validated in the athletes and patients with acromegaly but significantly (P < 0.01-0.001) over-predicted SM in the AN group as a whole. However, model 1 was validated in AN patients with BMIs in the model-development group range (n = 11; BMI of >16 kg/m(2)) but not in those with a BMI of <16 kg/m(2) (n = 12). The DXA-based models are accurate for predicting IMAT-free SM in selected populations and thus provide a new opportunity for quantifying SM in physiological and epidemiological investigations.

Absorptiometry, Photon↗

PubMed2004

Lifestyle behaviors associated with lower risk of having the metabolic syndrome.

The metabolic syndrome is a cluster of risk factors that predisposes individuals to cardiovascular disease (CVD) and diabetes and is present in almost one fourth of adult Americans. Risk factors involved with the metabolic syndrome can be altered via modifiable lifestyle factors, such as diet, physical activity, and smoking and drinking habits. The objective of this study was to examine the extent to which these modifiable lifestyle behaviors are associated with the risk of having the metabolic syndrome. Data from the Third National Health and Nutrition Examination Survey (NHANES III), conducted between 1988 and 1994, were used to measure the risk of having the metabolic syndrome in healthy adult Americans who follow certain lifestyle behaviors, such as dietary practices, levels of physical activity, smoking and drinking habits. Low physical activity level, high carbohydrate (CHO) intake, and current smoking habits were all significantly associated with an increased risk of having the metabolic syndrome, even after adjusting for other related covariates. Relative to physically inactive subjects, being physically active was associated with lower odds ratio (OR) (0.36, confidence interval [CI] 0.21 to 0.68, P < .01) in overweight men and in normal weight (0.36, CI 0.18 to 0.70, P < .01) and overweight (0.61, CI 0.38 to 0.97, P < .05) women. Although the type of CHO could not be distinguished, relative to a high CHO diet, men having a low or moderate CHO intake had a lower risk of having the metabolic syndrome with respective ORs of 0.41 (CI 0.24 to 0.67, P < .01) and 0.44 (CI 0.25 to 0.77, P < .01); no effect of dietary CHO was observed in women. Moderate alcohol consumption was not significantly related to the risk of having the metabolic syndrome in men, but was associated with a lower OR in women (0.76, CI 0.61 to 0.95, P < .05). Regression models indicate a reduced risk of having the metabolic syndrome when selected low-risk lifestyle factors are present in combination, particularly in subjects with body mass index (BMI) < 30 kg/m(2). According to our cross-sectional logistic models, the risk of having the metabolic syndrome is substantially lower in individuals who are physically active, nonsmoking, have a relatively low CHO intake and moderate alcohol consumption, and who maintain a BMI in the non-obese range. These observations have potentially important value for public health recommendations.

Adult↗

PubMed2004

Validation of an elliptical anthropometric model to estimate visceral compartment area.

OBJECTIVE: The visceral compartment is a surrogate for visceral adipose tissue. Cross-sectional visceral compartment area (VCA) has been approximated from waist circumference using a circular model. However, the two-dimensional shape of the abdomen is rarely circular. This study validated an elliptical model of cross-sectional total abdominal area (TAA), subcutaneous adipose tissue (SAT) area, and VCA at the L(4)-L(5) level. RESEARCH METHODS AND PROCEDURES: We analyzed magnetic resonance images (MRIs) at the level of the L(4)-L(5) intervertebral space from 35 subjects with a wide range of abdominal adiposity. Waist circumference, abdominal thickness (midline sagittal diameter), abdominal width (coronal diameter at one-half of abdominal thickness), and abdominal SAT thickness at four sites (front, back, right, and left) were measured from MRI images using an image analysis software. The same anatomical regions were also estimated from anthropometrics purely by geometric formulae of circular and elliptical models. A simple linear regression model was used to interpret the association strength between anthropometric estimates and MRI measures. RESULTS: Estimated TAA by either model was strongly related to MRI TAA (r(2) = 0.98, p < 0.0001). The SAT and VCA by MRI analysis showed a stronger association with calculation from an elliptical model (r(2) = 0.95 and 0.88, respectively; p < 0.001) than a circular model (r(2) = 0.69 and 0.25, respectively; p < 0.001). The absolute prediction residuals and variances were significantly smaller with an elliptical model than a circular model (p < 0.0001). DISCUSSION: An elliptical anthropometric model might be superior to a circular model to estimate abdominal SAT and VCA.

Abdomen↗