Visceral adipose tissue (VAT), which is linked with the metabolic consequences of obesity, is usually characterized by measuring VAT area at the L4–L5 vertebral interspace. However, the location of the slice with the strongest relation to VAT volume is not established.
We sought to investigate the relations between cross-sectional VAT areas at different anatomic locations and VAT volume in a large, diverse sample of healthy subjects.
VAT volume was derived from slice areas taken at 5-cm intervals from magnetic resonance images in 121 healthy men [x̄ ± SD age: 41.9 ± 15.8 y; body mass index (BMI; in kg/m2): 26.0 ± 3.2; VAT: 2.7 ± 1.8 L] and 198 healthy women (age: 48.1 ± 18.7 y; BMI: 27.0 ± 5.4; VAT: 1.7 ± 1.2 L). Regression models were developed to identify the best single slice for estimating VAT volume.
The VAT area 10 cm above L4–L5 (A+10) in men (R2 = 0.932, P < 0.001) and 5 cm above L4–L5 (A+5) in women (R2 = 0.945, P <0.001) had the highest correlation with abdominal VAT. R2 increased by only 3.8% in men and 0.5% in women with adjustment for age, race, scanning position, BMI, and waist circumference. Studies using A+10 in men and A+5 in women will require 14% and 9% fewer subjects, respectively, than those using slices at L4–L5 and will have equivalent power.
Measurement of slice areas at A+10 in men and A+5 in women provides greater power for the detection of VAT volume differences than does measurement at L4–L5.
Volume prediction; magnetic resonance imaging; computed tomography; body composition; L4-L5
Visceral adipose tissue (VAT) is associated with abnormal cardiovascular and metabolic profiles. Total VAT volume of the abdominal compartment by MRI is the gold standard measurement for VAT but is costly and time consuming. Prior studies suggest VAT area on a single slice MR image may serve as a surrogate for total VAT volume but it is unknown if this relationship is maintained in overweight and obese males and females.
Untreated sleep apnea subjects enrolled into the Icelandic Sleep Apnea Cohort underwent abdominal MRI. VAT area and subcutaneous adipose tissue (SAT) area at the L2-L3 and L4-L5 interspaces and total VAT and SAT volumes were determined by manual examination using image analysis software.
N=539 males and N=129 females with mean ages of 54.1 and 58.8 years and mean body mass index of 32.2 kg/m2 and 33.7 kg/m2, respectively, were studied. Mean total VAT volume was 40% smaller and mean total subcutaneous adipose tissue (SAT) was 25% larger among females compared to males. The correlation with VAT volume was significantly larger for L2-L3 VAT area (r=0.96) compared to L4-L5 VAT area (r=0.83). The difference in correlation coefficients was statistically significant (non-parametric bootstrap p<0.001 with 95% CI for the difference from 0.11 to 0.15. VAT area at L2-L3 was also significantly better correlated with VAT volume than traditional anthropometric variables. Linear regression analyses demonstrated that L2-L3 area alone was sufficient for predicting total VAT volume and that the nature of the linear association was maintained across all levels of obesity and in both genders.
We examined the relationship between visceral adipose tissue (VAT), independent of overall adiposity, and prevalent hypertension among adults enrolled in the Insulin Resistance Atherosclerosis (IRAS) Family Study. We also examined the role of insulin sensitivity (SI) upon hypertension. This was a cross-sectional epidemiological study in which African-American and Hispanic-American families were recruited from three clinical sites. The main outcome measure was prevalent hypertension, as defined by standardized protocol.
The relationship between VAT and prevalent hypertension was examined in adjusted marginal models among 1,582 participants. All continuous variables were standardized.
A significant VAT by gender interaction prompted separate analyses for VAT according to gender. Further adjustment for SI was performed to determine its potential role in the VAT-hypertension relationship. The mean age (SD) of the sample was 41.3 (13.8) years, with a mean BMI (SD) of 28.7 (6.0) kg/m2. Women comprised 58.5% of the sample (N = 925), and Hispanic-Americans comprised 69.2% of the sample (N=1095). One in five participants (21.2%) had prevalent hypertension. In women, VAT was significantly associated with hypertension, independent of BMI (OR = 1. 49 p= 0.006). African-American women demonstrated increased odds of prevalent hypertension compared to Hispanic-American women (OR = 3.08, p <0.001). Among men, VAT was not associated with hypertension independent of BMI, and BMI explained a significant amount of the variation in hypertension.
A significant relationship may exist between VAT and hypertension among women, but not men. The relationship between VAT and hypertension in women was not associated with insulin resistance.
visceral adipose tissue; body mass index; hypertension; insulin sensitivity; gender; African-Americans; Hispanic-Americans
To examine whether fatty liver, and abdominal visceral adipose tissue (VAT) are jointly associated with cardiometabolic abnormalities.
Methods and Results
African American participants were from the Jackson Heart Study (n=2882, 65% women) who underwent computed tomography. Fatty liver was measured by liver attenuation in Hounsfield Units (LA) and VAT was quantified volumetrically. Cross-sectional associations between LA, VAT, and cardiometabolic risk factors were assessed using linear and logistic regression, and their joint associations were further examined in 4 subgroups - (High-LA/Low-VAT [n=1704], Low-LA/Low-VAT [n=422], High-LA/High-VAT [n=436] and Low-LA/High-VAT [n=320]). Both LA and VAT were associated with most cardiometabolic traits (all p<0.0001), which persisted after additional adjustment for each other (LA, p < 0.01-0.0001 and VAT, p<0.0001). In bootstrap analyses, the regression coefficient of VAT was significantly greater than LA for triglycerides, HDL-C, impaired glucose and metabolic syndrome (MetS) (p range 0.009-0.0001). The interaction between LA and VAT was significant for HDL-C (p=0.002), impaired glucose (p=0.003) and MetS (p=0.04). Among 4 subgroups, participants with higher VAT and lower LA had higher prevalence of cardiometabolic traits than those with each condition alone.
Both fatty liver and VAT are independent correlates of cardiometabolic risk, but the associations are stronger for VAT than for fatty liver.
Jackson Heart Study; Intrahepatic fat; abdominal adiposity and cardiometabolic risk factors
Abdominal obesity conveys substantial health risks, in association with high levels of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and an increased proportion of VAT to SAT. The purposes were to determine the influence of spinal cord injury (SCI) on the associations between single axial cross-sectional area (CSA) slices and the average CSA or volumes of VAT and SAT across multi-axial slices of magnetic resonance imaging (MRI); and the relationships relative to the whole body composition and anthropometrics.
Thirteen healthy male participants with traumatic motor complete SCI underwent fast spin-echo MRI to measure VAT and SAT across multi-axial slices, followed by dual-energy X-ray absorptiometry to measure whole body fat-free mass (FFM) and fat mass (FM). Waist circumference (WC) was also measured in the seated position.
The trunk CSAs of VAT and SAT were 99 ± 51 and 164 ± 69 cm2, respectively, and the ratio of VAT to SAT was 0.68 ± 0.33. The CSAs of VAT and SAT at a single slice strongly predicted the average CSA and modestly predicted the volumes across multi-axial slices. VAT and SAT represented 5.7 ± 1.8% and 9.7 ± 3.2% of the total body FM, respectively. Percent body FFM was negatively related to VAT and SAT volumes, but not to a single axial CSA.
A single slice CSA can modestly predict the volume of multi-axial slices in individuals with SCI, yet it is not related to any of the body composition variables. Increased percent FFM is associated with a reduction in VAT and SAT volumes measured across multi-axial slices. The ratio of VAT to SAT is greater than 0.4, suggesting that individuals with SCI are at high risk of developing metabolic sequelae.
Spinal cord injuries; Body composition; MRI; DXA; Subcutaneous and visceral adipose tissue; Obesity
Visceral adipose tissue (VAT) is widely recognized as conveying the highest health risk in humans among the currently measurable adipose tissue compartments. A recent study indicated that the traditionally measured VAT area at L4–L5 is not the VAT area with the highest correlation with total VAT volume. At present, it is unknown whether the area with the highest correlation is also the most strongly associated with obesity-related health risk.
The study aim was to establish which VAT slice area(s) are most strongly associated with obesity-related health risk indicators.
The subjects were a convenience sample of healthy adults who completed whole-body magnetic resonance imaging (MRI) scans. The correlations, with appropriate adjustments, were examined between individual MRI slice VAT areas and fasting serum/plasma triglycerides (TG), high-density lipoprotein cholesterol (HDL), glucose, insulin and blood pressure.
The sample consisted of 283 healthy men (age (mean±s.d.) 41.9±15.8 years; BMI, 26.0±3.2 kg/m2; VAT, 2.7±1.8 L) and 411 women (age, 48.1±18.7 years; BMI 27.0±5.4 kg/m2; VAT, 1.7±1.2 L). After adjusting for age, race, menopause status, scan position and specific blood analysis laboratory, VAT area at L4–L5 had lower correlations with most metabolic risk factors including serum/plasma TG, HDL, glucose, insulin and blood pressure than VAT volume in both men and women. The VAT areas 10 and 15 cm above L4–L5 in men had higher or equal correlations with health risk measures than VAT volume. In women, the VAT area 5 cm above or below L4–L5 and total VAT volume had similar correlations with health risk measures.
An appropriately selected single slice VAT area is an equally reliable phenotypic marker of obesity-related health risk as total VAT volume. However, in both men and women the VAT slice area at the traditional L4–L5 level is not the best marker of obesity-related health risk.
metabolic syndrome; magnetic resonance imaging; computed tomography; body composition; abdominal obesity
Visceral adipose tissue (VAT) is associated with adverse health effects including cardiovascular disease and type 2 diabetes. We developed a dual-energy X-ray absorptiometry (DXA) measurement of visceral adipose tissue (DXA-VAT) as a low cost and low radiation alternative to computed tomography (CT). DXA-VAT was compared to VAT assessed using CT by an expert reader (E-VAT). In addition, the same CT slice was also read by a clinical radiographer (C-VAT) and a best-fit anthropomorphic and demographic VAT model (A-VAT) was developed. Whole body DXA, CT at L4–L5, and anthropometry were measured on 272 black and white South African women (age 29 ± 8 years, BMI 28 ± 7 kg/m2, waist circumference (WC) 89 ± 16 cm). Approximately one-half of the dataset (n = 141) was randomly selected and used as a training set for the development of DXA-VAT and A-VAT, which were then used to estimate VAT on the remaining 131 women in a blinded fashion. DXA-VAT (r = 0.93, standard error of the estimate (SEE) = 16 cm2) and C-VAT (r = 0.93, SEE = 16 cm2) were strongly correlated to E-VAT. These correlations with E-VAT were significantly stronger (P < 0.001) than the correlations of individual anthropometry measurements and the A-VAT model (WC + age, r = 0.79, SEE = 27 cm2). The inclusion of anthropometric and demographic measurements did not substantially improve the correlation between DXA-VAT and E-VAT. DXA-VAT performed as well as a clinical read of VAT from a CT scan and better than anthropomorphic and demographic models.
Visceral adipose tissue (VAT) is a source of inflammatory cytokines that in obese subjects may contribute to low-level systemic inflammation and development of metabolic syndrome. Expansion of VAT involves adipocyte hyperplasia and hypertrophy and requires breakdown of the extracellular matrix (ECM) and increased vascular outgrowth. To investigate changes of gene expression associated with VAT expansion and the role of combined genetics and diet we implemented gene microarray analyses of VAT in NONcNZO10 (NZ10) and control SWR/J mice subjected to control chow (CD) or a diet of high protein and fish oil (HPO). NZ10 mice on CD showed increased body weight, hyperglycemia and hyperinsulinemia at 25 weeks whereas those on HPO diet retained normal insulin levels and were normoglycemic. Two-way ANOVA revealed a significant interaction between diet and strain on blood glucose, serum insulin and percent fat but not for body weight. Microarray heat-maps revealed a remarkable combined effect of genetics and diet on genes that regulate ECM as well as angiogenic genes. RT-PCR confirmed markedly increased expression of Matrix Metalloproteinases (MMPs) -2, -3, -11, and -12, VEGF-A and C, Von Willebrand Factor (VWF) and PPARγ selectively in the NZ10/CD group. MMP-7 was significantly decreased. Protein levels of MMP-2, 3 and 9 were significantly increased in the VA of NZ10 mice fed CD while those of MMP-7 were down-regulated. Microarrays also revealed diet-dependent 2–4-fold increased expression of all 4 Tissue inhibitor of Metalloproteinases (TIMP) isoforms in NZ10 mice. Two-way ANOVA confirmed strongly interactive roles of diet and genetics on fat deposition and progression of T2D in this polygenic mouse model.
Adipose; Gene Expression; high protein fish oil diet; Matrix Metalloproteinase; angiogenesis
Both visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) have been linked to systemic inflammation in nondiabetic cohorts. We examined the relationships between VAT and SAT and systemic inflammatory markers in a large well-characterized cohort of subjects with type 2 diabetes.
RESEARCH DESIGN AND METHODS
Three hundred eighty-two subjects with type 2 diabetes in the CHICAGO (Carotid Intima-Media Thickness in Atherosclerosis Using Pioglitazone) study cohort underwent abdominal computed tomography to determine SAT and VAT distribution. Fasting blood was obtained for measurement of inflammatory markers. The relationships between inflammatory markers and BMI, SAT, and VAT were examined using regression models adjusted for age, sex, diabetes treatment, duration of diabetes, smoking, statin use, and A1C.
VAT was positively related to CRP, monocyte chemoattractant protein (MCP), intracellular adhesion molecule (ICAM)-1, and plasminogen activator inhibitor type 1 (PAI-1) antigen before adjustment for BMI. After adjustment for BMI, the relationship to CRP was lost but positive associations with MCP (P < 0.01), PAI-1 (P < 0.0001), ICAM-1 (P < 0.01), and vascular cell adhesion molecule (P = 0.01) were evident. BMI was positively related to CRP (P < 0.0001) and IL-6 (P < 0.01) even after adjustment for VAT and SAT. SAT was not related to any inflammatory marker after adjustment for BMI.
In this large group of subjects with type 2 diabetes, BMI was most strongly associated with CRP and IL-6 levels. SAT was not associated with markers of systemic inflammation. The size of the VAT depot provided information additional to that provided by BMI regarding inflammatory markers that are strongly related to vascular wall remodeling and coagulation. Our findings suggest that adipose tissue distribution remains an important determinant of systemic inflammation in type 2 diabetes.
Greater central adiposity is related to the risk of diabetes.
We aimed to test the hypothesis that central adiposity measured by computed tomography (CT) is a better predictor of the risk of diabetes than is body mass index (BMI), waist circumference (WC), waist/hip ratio (WHR), or waist/height ratio.
Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were measured at the L2–3 and L4–5 disc spaces in 1106 of the 3234 participants in the Diabetes Prevention Program. Sex-specific proportional hazards models were used to evaluate the association between VAT and SAT at both cuts, BMI, and other measures of central adiposity as predictors of the development of diabetes.
Men had more VAT than did women. White subjects had more VAT at both cuts than did other ethnic groups. The ratio of VAT to SAT was lowest in African Americans of both sexes. Among men in the placebo group, VAT at both cuts, WC, BMI, waist/height ratio, and WHR predicted diabetes (hazard ratio: 1.79–1.44 per 1 SD of variable). Among women in the lifestyle group, VAT at both cuts predicted diabetes as well as did BMI, and L2–3 was a significantly better predictor than was WC or WHR. SAT did not predict diabetes. None of the body fat measurements predicted diabetes in the metformin group.
In the placebo and lifestyle groups, VAT at both cuts, WHR, and WC predicted diabetes. No measure predicted diabetes in the metformin group. CT provided no important advantage over these simple measures. SAT did not predict diabetes.
Accumulation of adipose tissue is associated with cardiometabolic risks. Although visceral adipose tissue (VAT) has been strongly implicated in this relationship, there is still some debate regarding the contribution of abdominal subcutaneous adipose tissue (SAT). The purpose of this study was to determine the contribution of abdominal SAT to cardiometabolic risk factors, independent of total and visceral adiposity. These relationships were assessed in Caucasian and African Americans.
It is a cross-sectional analysis of the Pennington Center Longitudinal Study.
Data were extracted from 1246 participants. Total body fat mass (FM) was measured by dual-energy X-ray absorptiometry, whereas abdominal VAT and SAT areas (cm2) were measured with computed tomography. The cardiometabolic risk factors included resting blood pressure (BP), fasting blood glucose and triglyceride concentrations and high-density lipoprotein cholesterol (HDL-C).
Positive relationships across tertiles of VAT were seen for the participants with high glucose, high BP and low HDL-C (P<0.043). There was also a significant increase in the percentage of participants with two or more cardiometabolic risk factors across most tertiles of abdominal SAT (P<0.042). Logistic regression analysis showed that in univariate models, all adiposity measures were significantly associated with increased odds of having all risk factors in men and women. In multivariate models, VAT was significantly associated with most risk factors across gender. Abdominal SAT and FM (odds ratios (ORs) 1.3–2.1; all P<0.05) were associated with fewer risk factors after accounting for VAT. VAT (OR=5.9 and 5.3) and SAT (OR=2.0 and 1.8) were both associated with higher odds of the presence of two or more cardiometabolic risk factors in both males and females (P<0.001).
The data suggest that abdominal SAT is not protective against unfavorable cardiometabolic risk profiles. These conclusions were consistent across ethnic groups.
abdominal fat distribution; heart disease risk; epidemiology; ethnic differences
Despite the recognition that central obesity plays a critical role in chronic disease, few large-scale imaging studies have documented human variation in abdominal adipose tissue patterning.
We aimed to compare the associations between abdominal subcutaneous adipose tissue (ASAT) and visceral abdominal tissue (VAT), which were measured at different locations across the abdomen, and the presence of the metabolic syndrome (MS; National Cholesterol Education Program Adult Treatment Panel III definition) and individual cardiometabolic risk factors.
This study included 713 non-Hispanic whites aged 18–86 y, in whom VAT and ASAT were assessed by using multiple-image magnetic resonance imaging. The anatomical position of the magnetic resonance image containing the maximum VAT area for each subject was used as a measure of VAT patterning. Multivariate linear and logistic regression analyses were used to examine the relation of VAT, ASAT, and VAT patterning to cardiometabolic risk.
VAT mass was a stronger predictor of the MS than was ASAT mass, but ASAT mass (and other measures of subcutaneous adiposity) had signification interactions with VAT mass, whereby elevated ASAT reduced the probability of MS among men with high VAT (P = 0.0008). There was variation across image locations in the association of VAT area with the MS in men, and magnetic resonance images located 4–8 cm above L4–L5 provided the strongest correlations between VAT area and cardiometabolic risk factors. Subjects whose maximum VAT area was higher in the abdomen had higher LDL-cholesterol concentrations (R2 = 0.07, P = 0.0001), independent of age and adiposity.
Further studies are needed to confirm the effects of VAT patterning on cardiometabolic risk.
OBJECTIVE— The purpose of this study was to assess the relationship between lifestyle factors and abdominal subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) in a community-based setting.
RESEARCH DESIGN AND METHODS— Cross-sectional associations between lifestyle factors (dietary quality, physical activity, smoking, and alcohol consumption) and SAT and VAT volumes were examined in 2,926 Framingham Heart Study participants (48.6% women, aged 50 ± 10 years).
RESULTS— Diets consistent with the 2005 Dietary Guidelines Adherence Index and greater physical activity were inversely associated with SAT and VAT (P < 0.0001–0.002). In men, former smoking was associated with higher SAT (2,743 ± 56 cm3) compared with current smokers (2,629 ± 88 cm3) or those who never smoked (2,538 ± 44 cm3; P = 0.02). Both former and current smoking was associated with higher VAT (P = 0.03 [women]; P = 0.005 [men]). Women with high amounts of alcohol intake (>7 drinks/week) had lower SAT (2,869 ± 106 cm3) than those who consumed less alcohol (3,184 ± 44 cm3, P = 0.006); significant differences in VAT were not observed (P = 0.18). In men, high amounts of alcohol intake (>14 drinks/week) were associated with higher VAT (2,272 ± 59 cm3) compared with intake of ≤14 drinks/week (2,139 ± 25 cm3, P = 0.04), whereas SAT did not differ (P = 0.91). An increasing number of healthy lifestyle factors were associated with lower SAT and VAT volumes (all P < 0.003).
CONCLUSIONS— Adherence to recommended dietary guidelines and physical activity are associated with lower SAT and VAT volumes. However, both smoking and high alcohol intake are differentially associated with VAT volumes. Further research to uncover the putative mechanisms is warranted.
It is unknown whether measurement site of visceral adipose tissue (VAT) influences the relationship between VAT and associated health risk in youth and if so, whether ethnic differences exist in this relationship. We examined the influence of the measurement site of VAT on the relationships between VAT and metabolic syndrome (MetS) in African-American (AA) and American-White (AW) youth.
Healthy AA (n = 54) and AW (n = 54) children and adolescents (age: 8–18 yr; BMI: 15.3–42.5 kg/m2).
VAT mass was derived using a series of five transverse images measured by magnetic resonance imaging, extending from 5 cm below to 15 cm above L4-L5. MetS was defined using a modified IDF criteria.
In AA, VAT measure at 5 cm above L4-L5 (R2 = 0.93) was most strongly (p < 0.05) correlated with VAT mass and was a significantly (p < 0.05) stronger correlate as compared to L4-L5 (R2 = 0.84). In AW, VAT measures at 5 cm (R2 = 0.93) and 10 cm (R2 = 0.93) above L4-L5 were most strongly (p < 0.05) correlated with VAT mass; however, these were not stronger correlates as compared to L4-L5 (R2 = 0.91). In AW, all VAT measures were significantly (p < 0.05) associated with an increased odds ratio (OR) for prevalent MetS, wherein the VAT mass [OR = 5.32(1.9–15.0)] and VAT at L4-L5 [OR = 5.99(1.9–18.4)] were most strongly associated with MetS. In contrast, only VAT at 10 cm above L4-L5 [OR = 4.39 (1.1–18.1)] was significantly (p < 0.05) associated with MetS in AA.
In AA and AW youth, the measurement site for VAT has impact on the estimation of total VAT and the magnitude of the association with obesity-related health risks.
adolescents; insulin resistance; magnetic resonance imaging; metabolic syndrome; race; visceral adipose tissue
Adiponectin is reduced in obesity, and has been suggested to play an important role in modulation of atherosclerosis. We studied the relationship between visceral (VAT) and subcutaneous (SAT) adipose tissue and serum adiponectin concentrations in Japanese men. Participants were 304 randomly selected community-based Japanese men aged 40 to 49 without a prior history of cardiovascular disease. Participants were grouped according to tertiles of serum adiponectin. In multiple linear regression analysis including age, pack years of smoking, and alcohol intake as covariates, log-transformed adiponectin was inversely associated with both VAT and SAT when these two obesity measures were included separately in the models. However, log-transformed adiponectin was inversely associated with VAT (standardized β estimate= −0.465, P< 0.0001) and positively associated with SAT (standardized β estimate = 0.166, P=0.03), when these were included concomitantly in the model. In conclusion, VAT and SAT had differential associations with serum adiponectin concentrations.
Visceral adipose tissue (VAT) is an independent risk factor in cardiometabolic diseases and is commonly measured by computed tomography (CT). It is measured clinically by waist circumference (WC). The L4/5 intervertebral space VAT (L4/5 VAT) is traditionally used to represent total VAT volume. We set out to determine (1) the level of intervertebral space on CT that best approximates the total VAT volume; (2) compare the association between WC and VAT in Singaporean Chinese and Indian; and (3) examine the correlation between VAT and cardiometabolic risk factors.
A total of 60 Chinese and 60 Asian Indian men older than 60 years were recruited. Their medical history was taken and anthropometry was measured. Fasting glucose, insulin, lipids, adipokines and inflammatory markers were measured. Insulin resistance was evaluated by homeostasis model assessment-insulin resistance. VAT was determined by CT. Total VAT volume was calculated in 22 patients from VAT areas at seven intervertebral levels. The optimal VAT area most representative of total VAT volume was determined and used for all patients to approximate total VAT volume.
The VAT area at L2/3 intervertebral space (L2/3 VAT) correlated almost perfectly with VAT volume (R2=0.974 and 0.946 for Chinese and Indians, respectively). Subjects from the two races had similar height, weight, body mass index (BMI), WC and L2/3 VAT but more Indian men had hypertension, hyperlipidemia and type 2 diabetes mellitus. WC was correlated with the L2/3 VAT area in both Chinese (r=0.484, P<0.001) and Indian subjects (r=0.366, P=0.004) without racial difference (P=0.2 for interaction term). L2/3 VAT also correlated better with cardiometabolic risk factors, adipokines and C-reactive protein than WC, BMI or L4/5 VAT.
The L2-L3 intervertebral space was the best anatomic level for a single-slice CT cross-sectional area measurement of VAT to approximate total body visceral adipose volume in this population of Chinese and Asian Indian men older than 60 years. L2/3 VAT was better correlated with multiple cardiovascular risk factors, adipokines and inflammatory marker than either L4/5 VAT, WC or BMI.
visceral adipose tissue; waist circumference; metabolic syndrome; Chinese; Asian Indian; Singapore
The anatomic location of excess body fat has an impact on associated cardiometabolic morbidity, and visceral adipose tissue (VAT) is more pathogenic than subcutaneous adipose tissue (SAT). However, VAT or SAT alone provides little information regarding the relative distribution of body fat. We hypothesised that the propensity to store energy in VAT relative to SAT depots may be a correlate of cardiometabolic risk, and tested this hypothesis using the VAT/SAT ratio as a metric of fat distribution.
We investigated associations of the VAT/SAT ratio with cardiometabolic traits in 3,223 participants (48% women) from the Framingham Heart Study. Fat depots were quantified by multidetector computed tomography (CT) scanning.
In women and men, higher VAT/SAT ratio was associated (p<0.05) with most assessed cardiovascular risk factors reflecting blood pressure, dyslipidaemia and insulin resistance. Additional adjustment for BMI did not materially change the findings in women, and generally strengthened associations in men. Further adjustment for VAT attenuated some associations in women, but those with lower HDL-cholesterol, higher triacylglycerol (both p<0.0001) and higher prevalence of hypertension (p=0.02), diabetes (p=0.01) and the metabolic syndrome (p=0.005) remained significant. Similarly, in men, associations with higher systolic (p=0.006) and diastolic blood pressure (p=0.03), higher fasting glucose (p=0.0005), lower HDL-cholesterol and higher triacylglycerol (both p<0.0001) and higher prevalence of diabetes (p=0.006) remained significant.
VAT/SAT ratio is a correlate of cardiometabolic risk, above and beyond BMI and VAT. The propensity to store fat viscerally versus subcutaneously may be a unique risk factor independent of absolute fat volumes.
Body fat distribution; Obesity; Risk factors; Subcutaneous fat; Visceral fat
Volumetric visceral abdominal adipose tissue (VAT) and subcutaneous abdominal adipose tissue (SAT) as measured by computed tomography (CT) are associated with metabolic risk factors. We sought to identify the correlations of VAT and SAT between area-based measures at different anatomic locations with volumetric measurements to identify the optimal anatomic site, and to relate measurements at this site with metabolic risk factors.
We measured SAT and VAT volumes across the total imaging volume, whereas we measured SAT and VAT area at seven predefined anatomic landmarks in 200 participants from the Framingham Heart Study (mean age 54 years, 50% women) who underwent abdominal multi-detector CT. Correlation coefficients were used to assess the association between area measurements and volumes as well as metabolic risk factors stratified by gender.
Area-based measurements of SAT and VAT obtained at all anatomic landmarks were strongly associated with SAT and VAT volumes (all r>0.93, P<0.0001 and r>0.87, P<0.0001, for women and men; respectively). Consistently, area-based measurements of SAT and VAT obtained at L3/4 were most strongly associated with volumetric measured VAT and SAT independent of age (both r=0.99 in men, r=0.96 for SAT and r=0.99 for VAT in women, all P-value <0.0001) and were similarly correlated with risk factors compared with SAT and VAT volumes (all P<0.05 for fasting plasma glucose, triglycerides, high-density lipoprotein, systolic blood pressure).
Among area-based measurements of SAT and VAT, those obtained at the level of L3/4 were strongly associated with SAT and VAT volumes and cardio-metabolic risk factors in both men and women.
abdominal adiposity; adipose tissue quantification; single-slice measurement; computed tomography; cardiovascular risk factors
To elucidate the mathematical relationship between changes of visceral adipose tissue (VAT) and total body fat mass (FM) during weight loss.
We hypothesized that changes of visceral adipose tissue (VAT) mass are allometrically related to changes of total fat mass (FM), regardless of the type of weight loss intervention, as defined by the differential equation dVAT/dFM = k ×VAT/FM where k is a dimensionless constant. We performed a systematic search of the published literature for studies that included measurements of VAT changes via MRI or CT imaging along with measurements of FM changes by DEXA, hydrodensitometry, air-displacement plethysmography, or whole-body MRI or CT imaging. We then examined whether or not the data could be explained by the allometric model.
We found 37 published studies satisfying our search criteria, representing 1407 men and women of various ethnicities, degrees of adiposity, and weight loss interventions. The hypothesized allometric equation relating changes of VAT and FM accurately modeled the data for both men and women and for all methods of weight loss studied. The best-fit value for the dimensionless constant was k = 1.3 ± 0.1 and the resulting model had an R2 = 0.73.
This is the first report to reveal an allometric relationship between changes of VAT and FM that holds for both genders as well as a wide variety of weight loss interventions including bariatric surgery, caloric restriction with or without exercise, and exercise alone. We conclude that changes of VAT are primarily determined by FM changes as well as the initial VAT to FM ratio.
Weight loss; Visceral Adipose Tissue; Body Composition; Fat Mass; Allometry
Background & Aims
Visceral adipose tissue (VAT) is an important risk factor for the metabolic complications associated with obesity. Therefore, a reduction in VAT is considered an important target of obesity therapy. Therefore, we evaluated whether reducing VAT mass by surgical removal of the omentum, improves insulin sensitivity and metabolic function in obese patients.
We conducted: 1) a 12-month randomized controlled trial to determine whether reduction in VAT by omentectomy in 22 obese subjects enhances Roux-en-Y gastric bypass (RYGB) surgery-induced improvement in hepatic and skeletal muscle insulin sensitivity, assessed by using the hyperinsulinemic-euglycemic clamp technique, and 2) a 3-month longitudinal single-arm study to determine whether laparoscopic omentectomy alone in 7 obese subjects with type 2 diabetes mellitus (T2DM) improves insulin sensitivity, assessed by using the Frequently Sampled Intravenous Glucose Tolerance Test.
The greater omentum, weighing 0.82 kg (95% CI: 0.67–0.97) was removed from subjects who had omentectomy in both studies. In study 1, muscle insulin sensitivity (relative increase in glucose disposal during insulin infusion) approximately doubled and hepatic insulin sensitivity increased by ~4-fold at 12 months after RYGB alone and RYGB plus omentectomy compared with baseline (P<0.001). There were no significant differences between groups (P>0.87) or group×time interactions (P>0.36). In study 2, surgery had no effect on insulin sensitivity (P=0.844) and use of diabetes medications.
These results demonstrate that decreasing VAT through omentectomy, whether performed alone or in combination with RYGB surgery, does not improve metabolic function in obese patients.
intra-abdominal fat; portal hypothesis; insulin resistance; omentectomy
Elevated visceral adiposity is strongly predictive of cardiometabolic disease, but, due to the high cost of biomedical imaging, assessment of factors contributing to normal variation in visceral (VAT) and subcutaneous (SAT) adipose tissue partitioning in large cohorts of healthy individuals are few, particularly in ethnic and racial minority populations.
To describe age, menopausal status, smoking and physical activity differences in VAT and abdominal subcutaneous adipose tissue (ASAT) mass in African-American (AA) and European-American (EA) women.
Magnetic resonance imaging measures of VAT and ASAT mass and VAT% (VAT/VAT + ASAT, %) were obtained from a cross-sectional sample of 617 EA and 111 AA non-diabetic women aged 18–80 years. Multivariate linear regression was used to test independent effects of the covariates.
VAT and VAT% were higher in EA than AA women (p < 0.01). Differences in VAT, ASAT and VAT% across age groups began in early adulthood in both ethnic groups, but the association of age with VAT% was stronger in EA women (p for interaction = 0.03). Current smokers had higher VAT and VAT% (p < 0.01) and lower TBF than non-smokers. Frequent participation in sports activities was associated with ~ 30% lower VAT in older (> 55 years) as well as younger (< 40 years) women (p < 0.0001).
Greater allocation of abdominal adipose tissue into the visceral compartment occurs in EA than AA women and in older than younger women. Avoidance of cigarette smoking and frequent participation in sports activities may partially counteract this deleterious phenomenon of ageing.
Menopause; obesity; visceral adipose tissue; adiposity; magnetic resonance imaging; race; ethnicity; ageing; African-American; women
Increased aldosterone has been associated with obesity and the metabolic syndrome in non HIV-infected patients, but aldosterone has not been investigated among HIV-infected patients with increased visceral adipose tissue (VAT). 24-hour urine aldosterone was assessed among age and BMI-matched HIV-infected women with increased VAT, HIV-infected women without increased VAT and healthy controls. 24-hour urine aldosterone was higher in HIV-infected women with increased VAT and was associated with systolic blood pressure, VAT, and hemoglobin A1c. Increased aldosterone may contribute to the detrimental effects of excess visceral adiposity on blood pressure and glucose homeostasis among HIV patients.
Aldosterone; Lipodystrophy; HIV; Visceral Fat
Increased visceral adipose tissue (VAT) and intramyocellular lipids (IMCL) are associated with increased metabolic risk. Clinical and DXA body composition measures that are associated with VAT are generally even more strongly associated with subcutaneous adipose tissue (SAT) reflecting general adiposity, and thus are not specific for VAT. Measures more strongly associated with VAT than SAT (thus more specific for VAT), and predictors of IMCL have not been reported.
We studied 30 girls 12-18 years; 15 obese, 15 normal-weight. The following were assessed: (1) anthropometric measures: waist circumference at the umbilicus and iliac crest (WC-UC and WC-IC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), (2) DXA measures: total fat, percent body fat (PBF), percent trunk fat (PTF), trunk-to-extremity fat ratio (TEFR), (3) MRI and 1H-MRS: VAT and SAT (L4-L5), soleus-IMCL.
Group as a whole: WC, trunk fat and PBF were more strongly associated with SAT than VAT; none were specific for VAT. In contrast, PTF and TEFR were more significantly associated with VAT (r = 0.83 and 0.81 respectively, p <0.0001 for both) than SAT (r = 0.77 and 0.75, p < 0.0001 for both). Strongest associations of S-IMCL were with WHR (r = 0.66, p = 0.0004). Subgroup analysis: In obese girls, WHR and WHtR were more strongly correlated with VAT (r = 0.62 and 0.82, p = 0.04 and 0.001) than SAT (r = 0.41 and 0.73, p not significant and 0.007), and for DXA measures, PTF and TEFR were more significantly associated with VAT (r = 0.70 and 0.72, p = 0.007 and 0.006) than SAT (r = 0.52 and 0.53, p = 0.07 and 0.06). In controls, PTF and TEFR were more strongly correlated with VAT (r = 0.79, p = 0.0004 for both) than SAT (r = 0.71 and 0.72, p = 0.003 for both). WHR was associated with IMCL in obese girls (r = 0.78, p = 0.008), but not controls.
Overall, WHR (anthropometry), and PTF and TEFR (DXA) are good surrogates for IMCL and for visceral fat respectively in adolescent girls.
The link between central adiposity and cognition has been established by indirect measures such as body mass index (BMI) or waist–hip ratio. Magnetic resonance imaging (MRI) quantification of central abdominal fat has been linked to elevated risk of cardiovascular and cerebro-vascular disease. However it is not known how quantification of visceral fat correlates with cognitive performance and measures of brain structure. We filled this gap by characterizing the relationships between MRI measures of abdominal adiposity, brain morphometry, and cognition, in healthy elderly. Methods: A total of 184 healthy community dwelling elderly subjects without cognitive impairment participated in this study. Anthropometric and biochemical markers of cardiovascular risk, neuropsychological measurements as well as MRI of the brain and abdomen fat were obtained. Abdominal images were segmented into subcutaneous adipose tissue and visceral adipose tissue (VAT) adipose tissue compartments. Brain MRI measures were analyzed quantitatively to determine total brain volume, hippocampal volume, ventricular volume, and cortical thickness. Results: VAT showed negative association with verbal memory (r = 0.21, p = 0.005) and attention (r = 0.18, p = 0.01). Higher VAT was associated with lower hippocampal volume (F = 5.39, p = 0.02) and larger ventricular volume (F = 6.07, p = 0.02). The participants in the upper quartile of VAT had the lowest hippocampal volume even after adjusting for age, gender, hypertension, and BMI (b = −0.28, p = 0.005). There was a significant age by VAT interaction for cortical thickness in the left prefrontal region. Conclusion: In healthy older adults, elevated VAT is associated with negative effects on cognition, and brain morphometry.
cognitive aging; visceral adiposity; hippocampus; neuropsychological assessment; MRI
This study aimed to assess the correlation between abdominal subcutaneous adipose tissue (SAT) and metabolic syndrome (MetS) in Korean adults after adjusting for the effects of visceral adipose tissue (VAT).
RESEARCH DESIGN AND METHODS
The SAT/VAT ratio (SVR) was calculated using abdominal computed tomography in 2,655 subjects. We used regression analyses to assess whether the SVR predicted MetS.
For both sexes, the prevalence of elevated triglycerides, reduced HDL, and elevated fasting glucose significantly decreased with increasing quintiles of SVR (P for trend < 0.05). The prevalence and odds ratios of MetS significantly decreased as the SVR increased (men: odds ratio 0.5 [95% CI 0.3–0.7]; women: 0.2 [0.1–0.5] for comparisons of lowest vs. highest quintile; P for trend < 0.05).
After adjustment for VAT, abdominal SAT was inversely correlated with the occurrence of MetS.