Abdominal adipose tissue distribution and metabolic risk

The population distribution of the sagittal abdominal diameter (SAD) and SAD/height ratio among Finnish adults

Sagittal abdominal diameter (SAD; 'abdominal height' measured in supine position) may improve upon conventional anthropometry for predicting incident cardiometabolic diseases. However, the SAD is used infrequently by practitioners and epidemiologists. A representative survey of Finnish adults in 2000-2001 collected body measurements including SAD (by sliding-beam calliper) using standardized protocols. Sampled non-pregnant adults (ages 30+ years; 79% participation) provided 6123 SAD measurements from 80 health centre districts. Through stratified, complex survey design, these data represented 2.86 million adults at ages 30+ years. SAD ranged from 13.5 to 38.0 cm, with a population mean (standard error) of 21.7 (0.05) cm and median (interquartile range) of 21.0 (19.1-23.4). Median SAD was higher at ages 50+ years compared with ages 30-49 both for men (22.4 [20.5-24.6] vs. 20.8 [19.3-22.7]) and women (21.7 [19.6-23.9] vs. 19.4 [17.8-21.4]). The SAD/height ratio was similar (0.118) for both sexes at 30-39 years, rising more steeply with age for women than men. Attaining only a basic education, compared with a high level, was associated with increased mean (95% confidence interval) SADs for men (22.6 [22.3-22.8] vs. 22.0 [21.7-22.2]) and women (21.8 [21.5-22.0] vs. 20.6 [20.4-20.8]). Finland's early experience with nationally representative SAD measurements provides normative reference values and physiological insights useful for investigations of cardiometabolic risk.

A systematic review of the literature concerning the relationship between obesity and mortality in the elderly

INTRODUCTION

Obesity is a risk factor for chronic diseases and premature mortality, but the extent of these associations among the elderly is under debate. The aim of this systematic literature review (SR) is to collate and critically assess the available information of the impact of obesity on mortality in the elderly.

METHODS

In PubMed, there are three-hundred twelve papers on the relationship between obesity and mortality among older adults. These papers were analysed on the basis of their abstracts, and sixteen studies were considered suitable for the purpose of the study. It was possible to perform a pooled estimate for aggregated data in three different studies.

CONCLUSION

The results of this SR document that an increased mortality in obese older adults. The limitation of BMI to index obesity and the noted protective action of a moderate increase in BMI on mortality are highlighted. Waist circumference is an indicator of central adiposity and potentially as good a risk factor for mortality as BMI in obese elderly adults.

Indicadores antropométricos como marcadores de risco para anormalidades metabólicas

O objetivo do presente trabalho foi avaliar qual indicador antropométrico apresenta maior relação com as anormalidades metabólicas em participantes de um programa de Mudança de Estilo de Vida. Tratou-se de uma pesquisa do tipo exploratória, transversal e analítica, na qual foram avaliados 273 adultos e idosos (idade superior a 40 anos) quanto ao Índice de Massa Corporal (IMC), circunferência cintura (CC), % gordura corporal (GT) e % massa muscular (%MM). Foi colhida amostra de sangue em jejum para dosagem de colesterol total e frações, triacilglicerol e glicose. Foram realizadas análises estatísticas para diferenciação entre os grupos e determinação de associações. O nível de significância adotado foi de p<0,05. Ao avaliar as anormalidades metabólicas como variável dependente e IMC, CC, GT, %MM como variáveis independentes, observamos que a CC foi o indicador antropométrico que mostrou melhor associação com todas as anormalidades metabólicas (p<0,0001), seguida da %MM. Conclui-se que as anormalidades metabólicas comumente associadas à obesidade apresentam como principal marcador de risco antropométrico a CC e não o IMC. Dado um mesmo valor de CC, sobrepesos e obesos apresentaram riscos à saúde comparáveis aos indivíduos eutróficos.

[Resting metabolic rate and body composition in postmenopausal women]

OBJECTIVE

The present study evaluated the relationship between resting metabolic rate (RMR) and body composition of postmenopausal women.

METHODS

Thirty physically inactive women participated in the study, and their age average was 54,33 +/- 5,20 years old. Oxygen consumption was measured by indirect calorimetry after 12 hours of fasting and the values were calculated according to the equation of Weir. Body composition was obtained by the method of skinfolds and the measurement of waist circumference (WC) was used to assess abdominal fat. The linear correlation of Pearson was used to establish correlations between the variables.

RESULTS

We found significant correlations of TMR with the CC (0.42) and the lean mass (LM) (r = 0.48).

CONCLUSIONS

The variables of body composition that can be involved in the determination of the RMR are LM and WC.

Measurement site and the association between visceral and abdominal subcutaneous adipose tissue with metabolic risk in women

The associations between visceral adipose tissue (VAT) and abdominal subcutaneous adipose tissue (ASAT) and metabolic risk may be influenced by measurement site. The aim of this study was to compare the strength of the associations between VAT and ASAT, as assessed by a cross-sectional image (area) or total volume, and prevalent metabolic syndrome (MetS). We also examined the association between changes in abdominal AT area and volume with concomitant changes in metabolic risk. Abdominal AT volume and areas were derived using ~35 continuous computed tomography (CT) images from T10-T11 to L5-S1 in overweight or obese postmenopausal women before (n = 67) and after (n = 39) a 6-month exercise intervention. At baseline, measurement site did not influence the inter-relationship between ASAT area and total volume, and between ASAT and MetS. Conversely, VAT areas at L1-L2 and L2-L3 were stronger correlates of VAT volume at baseline (L1-L2 (r = 0.94), L2-L3 (r = 0.95), L4-L5 (r = 0.89)) and changes therein (L1-L2 (r = 0.77), L2-L3 (r = 0.75), L4-L5 (r = 0.55)) as compared to L4-L5, but were not significantly better predictors of MetS as compared to L4-L5 or the total volume (L2-L3: odds ratio (OR) = 2.68 (1.6-4.4), L1-L2: OR = 1.88 (1.2-3.0), L4-L5: OR = 2.56 (1.6-4.1), volume: OR = 2.07 (1.1-3.8)). Changes in VAT and ASAT were not associated with changes in MetS (P > 0.10). Although measurement site has an impact on the prediction of VAT volume, this does not translate into an improved prediction for the MetS. Thus, there is not enough evidence to support changing the current research practice of assessing VAT volume or at L4-L5 for the prediction of metabolic risk.

Influência da adiposidade sobre o risco inflamatório em pacientes com glicemia de jejum alterada

OBJETIVO: Investigar as alterações dos marcadores inflamatórios em obesos com glicemia de jejum alterada. MÉTODOS: Foram avaliados 125 indivíduos adultos tendo sido pesquisados: Índice de Massa Corporal, circunferência da cintura, glicemia de jejum, proteína C reativa ultra-sensível, ácido úrico e homocisteína. Os grupos apresentando glicemia de jejum normal (grupo 1) e glicemia de jejum alterada (grupo 2) foram comparados entre si e em associação aos subgrupos de obesos, sobrepesos e eutróficos. RESULTADOS: O grupo 2 apresentou maiores valores de circunferência da cintura (p<0,05), principalmente quando associados ao excesso de peso. Adicionalmente, o grupo 2 mostrou valores de proteína C reativa e ácido úrico superiores, sendo os dos obesos maiores que os com sobrepeso e os eutróficos, enquanto a homocisteína foi semelhante entre obesos, com sobrepeso e eutróficos. O Índice de Massa Corporal correlacionou-se positivamente com ambos ácido úrico (r=0,39, p<0,01) e proteína C reativa (r=0,37; p<0,01). A circunferência da cintura apresentou correlação apenas com o ácido úrico (r=0,53, p<0,01). Porém, a correlação entre Índice de Massa Corporal e proteína C reativa foi significante no grupo 2 (r=0,66, p<0,01), mas não no grupo 1 (r=0,25, p>0,05). O mesmo resultado foi encontrado em relação à circunferência da cintura e à proteína C reativa, que se correlacionaram significantemente somente na presença de glicemia de jejum alterada (r=0,40, p<0,05). Na regressão logística, a circunferência da cintura foi a variável explicativa (11%, p<0,01) da alteração da glicemia de jejum. CONCLUSÃO: Os estados pró-oxidativo e pró-inflamatório estiveram significantemente associados à glicemia de jejum alterada na presença de adiposidade corporal.

L-carnitine supplementation and physical exercise restore age-associated decline in some mitochondrial functions in the rat

In mammals, during the aging process, an atrophy of the muscle fibers, an increase in body fat mass, and a decrease in skeletal muscle oxidative capacities occur. Compounds and activities that interact with lipid oxidative metabolism may be useful in limiting damages that occur in aging muscle. In this study, we evaluated the effect of L-carnitine and physical exercise on several parameters related to muscle physiology. We described that supplementing old rats with L-carnitine at 30 mg/kg body weight for 12 weeks (a) allowed the restoration of L-carnitine level in muscle cells, (b) restored muscle oxidative activity in the soleus, and (c) induced positive changes in body composition: a decrease in abdominal fat mass and an increase in muscle capabilities without any change in food intake. Moderate physical exercise was also effective in (a) limiting fat mass gain and (b) inducing an increase in the capacities of the soleus to oxidize fatty acids.

Genetic analysis of self-reported physical activity and adiposity: the Southwest Ohio Family Study

OBJECTIVE

Physical inactivity poses a major risk for obesity and chronic disease, and is influenced by both genetic and environmental factors. However, the genetic association between physical activity (PA) level and obesity is not well characterized. Our aims were to: (i) estimate the extent of additive genetic influences on physical activity while adjusting for household effects; and (ii) determine whether physical activity and adiposity measures share common genetic effects.

SUBJECTS

The sample included 521 (42 % male) adult relatives, 18-86 years of age, from five large families in the Southwest Ohio Family Study.

DESIGN

Sport, leisure and work PA were self-reported (Baecke Questionnaire of Habitual Physical Activity). Total body and trunk adiposity, including percentage body fat (%BF), were measured using dual-energy X-ray absorptiometry. Abdominal visceral and subcutaneous adipose tissue mass were measured using MRI.

RESULTS

Heritabilities for adiposity and PA traits, and the genetic, household and environmental correlations among them, were estimated using maximum likelihood variance components methods. Significant genetic effects (P < 0.05) were found for sport (h2 = 0.26) and leisure PA (h2 = 0.17). Significant (P < 0.05) household effects existed for leisure PA (c2 = 0.25). Sport PA had a negative genetic correlation with central adiposity measurements adjusted for height (rhoG > |-0.40|). Sport and leisure PA had negative genetic correlations with %BF (rhoG > |-0.46|).

CONCLUSIONS

The results suggest that the association of sport and leisure PA with lower adiposity is due, in part, to a common genetic inheritance of both reduced adiposity and the predisposition to engage in more physical activity.

Correlation between omental TNF-α protein and plasma PAI-1 in obesity subjects

BACKGROUND

The role of TNF-alpha in contributing to obesity-associated cardiovascular and metabolic risk has gained much attention.

MATERIALS AND METHODS

Paired biopsies of omental and subcutaneous fat were collected from 16 lean subjects and 32 central obesity subjects. The expression of TNF-alpha in omental and subcutaneous fat was quantified by western blotting method, and correlations with plasma PAI-1, homeostasis model assessment insulin resistance (HOMA-IR), and lipid were investigated.

RESULTS

In obese female, TNF-alpha expression was higher in the omental than in the subcutaneous fat tissue. There was no significant difference in the levels of TNF-alpha between subcutaneous and visceral fat in obese male. Significant positive correlations were found between omental TNF-alpha protein and plasma PAI-1 levels in obesity. In obese female subjects, omental TNF-alpha protein levels showed a close association with most of the parameters studied: fasting glucose (r=0.541, P<0.05); fasting insulin (r=0.599, P<0.01); HOMA-IR (r=0.546, P<0.05); triglycerides (r=0.469, P<0.05); HDL-cholesterol (r=-0.759, P<0.01). In obese male population, correlations between omental TNF-alpha protein levels and fasting glucose (r=0.762, P<0.01); fasting insulin (r=0.622, P<0.05); triglycerides (r=0.650, P<0.05); HDL-cholesterol (r=-0.880, P<0.01) were found.

CONCLUSION

Omental TNF-alpha may play a key role in contributing to cardiovascular risk in central obesity subjects.

Expression of TNF-alpha protein in omental and subcutaneous adipose tissue in obesity

BACKGROUND

During the last several years the role of adipose tissue in contributing to obesity-associated cardiovascular and metabolic risk has gained much attention.

AIM

To examine the expression of TNF-alpha protein in omental and subcutaneous adipose tissue in correlation with plasma PAI-1 and other clinical parameters in obesity subjects.

MATERIAL AND METHODS

Paired biopsies of omental and subcutaneous fat were collected during surgery in 32 obesity subjects. The expression of TNF-alpha protein in omental and subcutaneous fat was quantified by using Western blot method, and correlations with plasma PAI-1, homeostasis model assessment insulin resistance (HOMA-IR) and lipid were investigated.

RESULTS

TNF-alpha protein expression was higher in omental than in subcutaneous adipose tissue (P<0.01). Significant positive linear correlations were found between TNF-alpha protein in omental adipose tissue and plasma PAI-1 in obesity subjects. TNF-alpha protein in omental fat was positively associated with HOMA-IR, triglycerides and negatively with HDL-cholesterol.

CONCLUSION

TNF-alpha expression in omental adipose tissue could play a key role in contributing to cardiovascular risk in central obesity subjects.

Differential activation of the sympathetic innervation of adipose tissues by melanocortin receptor stimulation

Melanocortins are implicated in the control of energy intake/expenditure. Centrally administered melanotan II (MTII), a synthetic melanocortin 3/4-receptor agonist, decreases adiposity beyond that accountable by food intake decreases. Melanocortin-4 receptor (MC4-R) mRNA is expressed on sympathetic nervous system (SNS) outflow neurons to white adipose tissue (WAT) in Siberian hamsters, suggesting a role in lipid mobilization. Therefore, we tested whether third ventricular injections of MTII increased sympathetic drive to WAT and interscapular brown adipose tissue (IBAT) using norepinephrine turnover (NETO) as a measure of sympathetic drive. We also tested for MTII-induced changes in lipolysis-related WAT gene expression (beta3-adrenoceptors, hormone sensitive lipase) and IBAT thermogenesis (beta3-adrenoceptor, uncoupling protein-1). Finally, we tested whether third ventricularly injected MTII, a highly selective MC4-R agonist (cyclo[beta-Ala-His-D-Phe-Arg-Trp-Glu]NH2) increased or agouti-related protein decreased IBAT temperature in hamsters implanted with sc IBAT temperature transponders. Centrally administered MTII provoked differential sympathetic drives to WAT and IBAT (increased inguinal WAT, dorsosubcutaneous WAT and IBAT NETO, but not epididymal WAT and retroperitoneal WAT NETO). MTII also increased circulating concentrations of the lipolytic products free fatty acids and glycerol but not plasma catecholamines, suggesting lipid mobilization via WAT SNS innervation and not via adrenal medullary catecholamines. WAT or IBAT gene expression was largely unaffected by acute MTII treatment, but IBAT temperature was increased by MTII and the MC4-R agonist and decreased by agouti-related protein. Collectively, this is the first demonstration of central melanocortin agonist stimulation of WAT lipolysis through the SNS and confirms melanocortin-induced changes in BAT thermogenesis.

Thematic review series: adipocyte biology. Sympathetic and sensory innervation of white adipose tissue

During our study of the reversal of seasonal obesity in Siberian hamsters, we found an interaction between receptors for the pineal hormone melatonin and the sympathetic nervous system (SNS) outflow from brain to white adipose tissue (WAT). This ultimately led us and others to conclude that the SNS innervation of WAT is the primary initiator of lipid mobilization in these as well as other animals, including humans. There is strong neurochemical (norepinephrine turnover), neuroanatomical (viral tract tracing), and functional (sympathetic denervation-induced blockade of lipolysis) evidence for the role of the SNS in lipid mobilization. Recent findings suggest the presence of WAT sensory innervation based on strong neuroanatomical (viral tract tracing, immunohistochemical markers of sensory nerves) and suggestive functional (capsaicin sensory denervation-induced WAT growth) evidence, the latter implying a role in conveying adiposity information to the brain. By contrast, parasympathetic nervous system innervation of WAT is characterized by largely negative neuroanatomical evidence (viral tract tracing, immunohistochemical and biochemical markers of parasympathetic nerves). Functional evidence (intraneural stimulation and in situ microdialysis) for the role of the SNS innervation in lipid mobilization in human WAT is convincing, with some controversy regarding the level of sympathetic nerve activity in human obesity.

Estimating abdominal adipose tissue with DXA and anthropometry

OBJECTIVE

To identify an anatomically defined region of interest (ROI) from DXA assessment of body composition that when combined with anthropometry can be used to accurately predict intra-abdominal adipose tissue (IAAT) in overweight/obese individuals.

RESEARCH METHODS AND PROCEDURES

Forty-one postmenopausal women (age, 49 to 66 years; BMI, 26 to 37 kg/m(2)) underwent anthropometric and body composition assessments. ROI were defined as quadrilateral boxes extending 5 or 10 cm above the iliac crest and laterally to the edges of the abdominal soft tissue. A single-slice computed tomography (CT) scan was measured at the L3 to L4 intervertebral space, and abdominal skinfolds were taken.

RESULTS

Forward step-wise regression revealed the best predictor model of IAAT area measured by CT (r(2) = 0.68, standard error of estimate = 17%) to be: IAAT area (centimeters squared) = 51.844 + DXA 10-cm ROI (grams) (0.031) + abdominal skinfold (millimeters) (1.342). Interobserver reliability for fat mass (r = 0.994; coefficient of variation, 2.60%) and lean mass (r = 0.986, coefficient of variation, 2.67%) in the DXA 10-cm ROI was excellent.

DISCUSSION

This study has identified a DXA ROI that can be reliably measured using prominent anatomical landmarks, in this case, the iliac crest. Using this ROI, combined with an abdominal skinfold measurement, we have derived an equation to predict IAAT in overweight/obese postmenopausal women. This approach offers a simpler, safer, and more cost-effective method than CT for assessing the efficacy of lifestyle interventions aimed at reducing IAAT. However, this warrants further investigation and validation with an independent cohort.

Anthropometric risk factors for patellar tendon injury among volleyball players

OBJECTIVE

Abnormal imaging in the patellar tendon reveals pathology that is often associated with knee pain. Anthropometric measures of body size and mass, such as height, weight and waist-to-hip ratio (WHR), have been individually associated with abnormal imaging. The aim of this study was to investigate the anthropometric factors that have the strongest relationship with abnormal imaging in volleyball players.

METHODS

Height, weight, body mass index (BMI), waist girth, hip girth and WHR were measured in a cohort of 113 competitive volleyball players (73 men, 40 women). The univariate (ANOVA) and multivariable (discriminant function analysis) association between abnormal imaging and these anthropometric factors were investigated.

RESULTS

No significant association was found in the female volleyball players. A significant univariate association was observed between abnormal imaging and heavier weight, greater BMI, larger waist and hip girth and larger WHR in the male volleyball players. Waist girth was the only factor that retained this association in a multivariable model (p<0.05).

CONCLUSIONS

Men with a waist girth greater than 83 cm seem to be at greater risk of developing patellar tendon pathology. There may be both mechanical and biochemical reasons for this increased risk.

Contribution of CB1 blockade to the management of high-risk abdominal obesity

The worldwide increase in the prevalence of type 2 diabetes represents a tremendous challenge for our healthcare system, especially if we consider that this phenomenon is largely explained by the epidemic of obesity. However, despite the well-recognized increased morbidity and mortality associated with an elevated body weight, there is now more and more evidence highlighting that abdominal adipose tissue is the fat depot that conveys the greatest risk of metabolic complications. This cluster of metabolic abnormalities has been referred to as the metabolic syndrome and this condition is largely the consequence of abdominal obesity, especially when accompanied by a high accumulation of visceral adipose tissue. This cluster of metabolic complications has also been found to be predictive of a substantially increased risk of coronary heart disease beyond the presence of traditional risk factors. Moreover, a moderate weight loss in initially abdominally obese patients is associated with a selective mobilization of visceral adipose tissue, leading to improvements in the metabolic risk profile predictive of a reduced risk of coronary heart disease and of type 2 diabetes. The recent discovery of the endocannabinoid-CB1 receptor system and of its impact on the regulation of energy metabolism represents a significant advance, which will help physicians target abdominal obesity and its related metabolic complications. In this regard, studies have shown that rimonabant therapy (the first developed CB1 blocker) could be useful for the management of clustering cardiovascular disease risk factors in high-risk abdominally obese patients through its effects not only on energy balance but also on adipose tissue metabolism. For instance, the presence of CB1 receptors in adipose tissue and the recently reported effect of rimonabant on adiponectin production by adipose cells may represent a key factor responsible for the weight loss-independent effect of this CB1 blocker on cardiometabolic risk variables.

Weight-dependent changes of immune system in adipose tissue: importance of leptin

Ancestral lymphoid cells reside in adipose tissues, and their numbers are highly altered in obesity. Leptin, production of which is correlated to fat mass, is strongly involved in the relationships between adipose tissues and immune system. We investigated in epididymal (EPI) and inguinal (ING) fat pads to determine whether 1) lymphocyte phenotypes were correlated to the tissue weight and 2) leptin was involved in such relationships. Immunohistological analyses revealed a tight relationship between the T and NK lymphocytes of the stromal vascular fraction and adipocytes. We identified a significant negative and positive correlation between EPI weight and the percentage of NK and total T cells respectively by cytofluorometric analyses. The NK and ancestral gammadelta T cell contents were directly dependent of leptin since they increased significantly in high-fat (HF) diet mice but not in leptin-deficient (ob/ob) mice as compared to control. By contrast, the alphabeta T cell content seemed independent of leptin because their percentages increased significantly with the EPI weight whatever the type of mice (control, HF, ob/ob). The present study suggests that adipose tissues present, according to their localization, different immunological mechanisms that might be involved in the regulation of adipose cells functions and proliferations.

Body mass index is inversely related to mortality in older people after adjustment for waist circumference

OBJECTIVES

To examine the individual and combined influence of body mass index (BMI) and waist circumference (WC) on mortality risk in older people.

DESIGN

Longitudinal cohort study.

SETTING

Cardiovascular Health Study, a longitudinal study of cardiovascular disease and its risk factors in older people.

PARTICIPANTS

Five thousand two hundred men and women aged 65 and older.

MEASUREMENTS

BMI and WC were measured at baseline. The risks of all-cause mortality associated with BMI and WC were examined using Cox proportional hazards models over 9 years of follow-up.

RESULTS

When examined individually, BMI and WC were both negative predictors of mortality, but when BMI and WC were examined simultaneously, BMI was a negative predictor of mortality, whereas WC was a positive predictor of mortality. After controlling for WC, mortality risk decreased 21% for every standard deviation increase in BMI. After controlling for BMI, mortality risk increased 13% for every standard deviation increase in WC. The patterns of associations were consistent by sex, age, and disease status.

CONCLUSION

Higher BMI values indicated a lower mortality risk once the risk attributable to WC was accounted for, whereas higher WC values indicate a higher mortality risk once the risk attributable to BMI was accounted for. Both BMI and WC should be measured in the clinical setting, but in older adults higher BMI is associated with lower mortality rates.

Combined influence of body mass index and waist circumference on coronary artery disease risk factors among children and adolescents

OBJECTIVES

In adult populations, it is recognized widely that waist circumference (WC) predicts health risk beyond that predicted by BMI alone; current recommendations for adults are that a combination of BMI and WC be used to classify obesity-related health risk. For children and adolescents, however, little is known about the combined influence of BMI and WC on health outcomes. The objectives of this study were to determine whether BMI and WC predict coronary artery disease (CAD) risk factors independently for children and adolescents and to assess the clinical utility of using WC in combination with BMI to identify CAD risk.

METHODS

Subjects included 2597 black and white, 5- to 18-year-old, male and female youths. Outcome measures included 7 CAD risk factors. In the first analysis step, BMI and WC were used as continuous variables to predict CAD risk factors. In the second analysis step, participants were placed into normal-weight, overweight, and obese BMI categories and, within each BMI category, CAD risk factors were compared for groups with low and high WC values.

RESULTS

When BMI and WC were included in the same regression model to predict CAD risk factors, the added variance above that predicted by BMI or WC alone was minimal, which indicated that BMI and WC did not have independent effects on the risk factors. For example, for systolic blood pressure, BMI alone explained 7.3% of the variance, WC alone explained 7.7% of the variance, and the combination of BMI and WC explained 8.1% of the variance. When BMI and WC values were categorized with a threshold approach, WC provided information on CAD risk beyond that provided by BMI alone, particularly when the categories were used to predict elevated CAD risk factor levels. For instance, in the overweight BMI category, the high-WC group was approximately 2 times more likely to have high triglyceride levels, high insulin levels, and the metabolic syndrome, compared with the low-WC group.

CONCLUSION

These findings provide some evidence that a combination of BMI and WC should be used in clinical settings to evaluate the presence of elevated health risk among children and adolescents.

Body composition and fat distribution influence systemic hemodynamics in the absence of obesity: the HyperGEN Study

BACKGROUND

We have shown that increased cardiac output is related to both fat-free mass and fat mass in obesity.

OBJECTIVE

We studied the association of body fat distribution and body composition with flow-resistance relations in overweight.

DESIGN

We studied 521 overweight, nonobese participants in the Hypertension Genetic Epidemiology Network (HyperGEN) Study-a component of the National Heart, Lung, and Blood Institute Family Blood Pressure Program, designed to assess the genetic basis of hypertension. Participants had normal ventricular function and no cardiovascular disease: 261 with central fat distribution (CFD) (waist girth >88 cm in women and >102 cm in men) and 260 with peripheral fat distribution (PFD). Fat-free mass (FFM) and fat mass (FM) were measured by bioelectric impedance. Body composition was estimated as FM/FFM. Echocardiographic stroke volume (SV) and cardiac output (CO) were measured.

RESULTS

Hypertension was present in 73% of the subjects with PFD and in 78% with CFD. Overweight with CFD was associated with greater FM/FFM in both normotensive and hypertensive participants. After FFM, age, sex, and race were controlled for, SV and CO were higher in subjects overweight with CFD than in those with PFD, whereas peripheral resistance was not significantly different. Differences in CO between CFD and PFD were reduced after further adjustment for FM. After the covariates were controlled for, hypertensive subjects had higher peripheral resistance and lower arterial compliance than did normotensive participants, but cardiac output was not significantly different.

CONCLUSION

CFD is associated with more severe abnormalities in body composition and with higher CO independently of FFM in overweight, nonobese subjects.

Relation between whole-body and regional measures of human skeletal muscle

BACKGROUND

It is unknown whether regional measures of skeletal muscle (SM) in the thigh and abdomen accurately reflect whole-body SM mass.

OBJECTIVE

We aimed to determine whether thigh and abdominal SM measures reflect whole-body SM mass and, if so, which region is a stronger marker.

DESIGN

Whole-body and regional measures of SM were obtained by magnetic resonance imaging in a sample of 387 white men and women.

RESULTS

The regional SM measures, whether obtained by using a single image (midthigh or L4-L5 level) or a series of 7 consecutive images covering 31 cm (thigh or abdomen), were strongly correlated with whole-body SM (P < 0.001). Independent of sex, the thigh SM measures derived from a single image (men: R(2) = 0.77, SEE = 6.5%; women: R(2) = 0.79, SEE = 7.4%) or a series of 7 consecutive images (men: R(2) = 0.84, SEE = 5.4%; women: R(2) = 0.90, SEE = 5.1%) were stronger correlates of whole-body SM with smaller SEE values than were the abdominal SM measures (P < 0.01). However, SM in the abdomen was also a strong marker of whole-body SM, whether determined from a single image at the L4-L5 level (men: R(2) = 0.63, SEE = 8.2%; women: R(2) = 0.58, SEE = 10.4%) or from a series of images across the abdomen (men: R(2) = 0.77, SEE = 6.5%; women: R(2) = 0.70, SEE = 8.7%).

CONCLUSION

Although thigh measures of SM are better predictors of whole-body SM, a single image within the abdomen routinely used to estimate abdominal fat may also be a useful marker of whole-body SM.

Interindividual variation in abdominal subcutaneous and visceral adipose tissue: influence of measurement site

We evaluated the influence of measurement site on the ranking (low to high) of abdominal subcutaneous (SAT) and visceral (VAT) adipose tissue. We also determined the influence of measurement site on the prediction of abdominal SAT and VAT mass. The subjects included 100 men with computed tomography (CT) measurements at L4–L5 and L3–L4 levels and 100 men with magnetic resonance imaging (MRI) measurements at L4–L5 and 5 cm above L4–L5 (L4–L5 +5 cm). Corresponding mass values were determined by using multiple-image protocols. For SAT, 90 and 92 of the 100 subjects for CT and MRI, respectively, had a difference in rank position at the two levels. The change in rank position exceeded the error or measurement for ∼75% of the subjects for both methods. For VAT, 91 and 95 of the 100 subjects for CT and MRI, respectively, had a difference in rank position at the two levels. The change in rank position exceeded the error of measurement for 36% of the subjects for CT and for 8% of the subjects for MRI. For both imaging modalities, the variance explained in SAT and VAT mass (kg) was comparable for L4–L5, L4–L5 +5 cm, and L3–L4 levels. In conclusion, the ranking of subjects for abdominal SAT and VAT quantity is influenced by measurement location. However, the ability to predict SAT and VAT mass by using single images obtained at the L4–L5, L4–L5 +5 cm, or L3–L4 levels is comparable.