Visceral Adipose Tissue Levels Research Articles

Contribution of metabolic and anthropometric abnormalities to cardiovascular disease risk factors.

Patients with human immunodeficiency virus (HIV) infection have sustained alterations in metabolism (lipids and insulin/glucose homeostasis) and body composition (fat distribution) that are proatherogenic (the Figure). HIV infection itself and/or its therapies may contribute to these alterations (the Table); although most effects are reversible, there are some possibly irreversible consequences of treatment. With the relative restoration to health seen in the era of highly active antiretroviral therapy (HAART), many traditional risk factors and promoters of dyslipidemia and diabetes also are present; they interact with HIV-specific inducers to worsen dyslipidemia and to increase the prevalence of insulin resistance and diabetes. Figure. Overview of the effects of HIV and its therapies on CVD risk. The contribution of traditional risk factors must be kept in mind, and they may occur with increased prevalence in people with HIV infection (eg, smoking). HIV, likely through the inflammatory response, and antiretroviral therapies independently affect many of the mediators of CVD risk. The effects on lipids are a prominent but complex example; HIV infection lowers LDL levels, but antiretroviral therapy raises LDL back up to normal levels. The bidirectional arrows indicate associations, but there is not yet adequate proof of causality. The dotted arrow between body composition and CVD indicates that body fat is known to affect the mediators such as dyslipidemia and insulin resistance but may also have a direct effect. FFA indicates free fatty acids; ARV, antiretroviral. View this table: Table. Effects of HIV Treatment These disturbances in lipid and glucose metabolism and renal disease may contribute, at least in part, to the excess cardiovascular disease (CVD) morbidity and mortality observed in HIV-infected individuals (the Figure). However, the relative contribution to excess CVD risk of traditional CVD risk factors, especially smoking, compared with these infection- and treatment-specific complications requires clarification. More prospective data with multivariable modeling are needed. …

Visceral Obesity and Plasma Glucose-Insulin Homeostasis: Contributions of Interleukin-6 and Tumor Necrosis Factor-α in Men

This study examined the relationships of two inflammatory cytokines, IL-6 and TNF-alpha, to visceral adiposity and indices of plasma glucose-insulin homeostasis. Plasma levels of IL-6 and TNF-alpha were measured in 189 untreated asymptomatic men (aged 43.7 +/- 7.8 yr; body mass index 29.0 +/- 4.3 kg/m(2); waist girth 98.6 +/- 10.3 cm). Significant and positive associations were found between both cytokines with adiposity and adipose tissue distribution indices (0.15 < or = r < 0.32; P < 0.05) as well as plasma glucose-insulin homeostasis variables (0.22 < or = r < 0.28; P <0.05). Comparison of two subgroups, each composed of 32 overweight men (> or =25 kg/m(2)) with similar body mass index values (28.7 kg/m(2) in both groups) but with markedly different levels of visceral adipose tissue (< vs. > or = 130 cm(2)), revealed significant differences only for IL-6 levels (1.42 +/- 1.15 vs. 0.86 +/- 0.52 pg/ml; P < 0.02 for men with high vs. low visceral adipose tissue, respectively). Finally, when subjects were stratified on the basis of their respective concentrations of IL-6 and TNF-alpha (using the 50th percentile of their overall distribution), an ANOVA revealed an independent contribution of IL-6 to the variation of fasting insulin (P < 0.01) and each of these two cytokines to the variation of insulin levels measured after a 75-g oral glucose challenge (P <0.01 for IL-6 and P < 0.05 for TNF-alpha). Because IL-6 appeared to be clearly associated with visceral adiposity, TNF-alpha rather showed associations with indices of total body fatness. Thus, TNF-alpha may contribute to the insulin resistance of overall obesity, whereas IL-6 may be one of the mediators of the hyperinsulinemic state specifically related to excess visceral adiposity.

Visceral adipose tissue and the ratio of visceral to subcutaneous adipose tissue are greater in adults with than in those without spinal cord injury, despite matching waist circumferences

Background: Abdominal obesity, particularly visceral adipose tissue (VAT), is associated with an increased risk of coronary heart disease (CHD). Despite an elevated risk of CHD mortality in persons with spinal cord injury (SCI), neither abdominal adipose tissue accumulation nor the validity of waist circumference (WC) has been determined in persons with SCI.Objectives: The objectives of this study were to compare total adipose tissue (TAT), visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and the ratio of VAT to SAT (VAT:SAT) between adults with SCI and age-, sex-, and WC-matched able-bodied (AB) controls and to determine the relation between WC and VAT in both groups.Design: Thirty-one men and women (n = 15 SCI and 16 AB) with a mean (±SD) age of 38.9 ± 7.9 y participated in this cross-sectional study. Abdominal adipose tissue was quantified by computed tomography at L4-L5. WC was measured at 3 sites: lowest rib, iliac crest, and the midpoint between the lowest rib and iliac crest.Results: Persons with SCI had a 58% greater mean VAT (P = 0.003), 48% greater mean VAT:SAT (P = 0.034), and 26% greater mean TAT (P = 0.055) than did matched AB controls after differences in weight were accounted for. Mean SAT was not significantly different between groups. WC at all sites was correlated with VAT in both groups (SCI: 0.905 ≤ r ≤ 0.925; AB: 0.838 ≤ r ≤ 0.877; both P < 0.001).Conclusions: High levels of VAT exist in young people with SCI who classify themselves as active and healthy. WC may be a valid surrogate measure of VAT in this population and serve as a tool for clinicians to identify those at risk of CHD.

Critical visceral adipose tissue thresholds aassociated with type 2 diabetes mellitus in chinese population

Objective To compare intervertebral location L2-L3 with L4-L5 as landmarks for measuring abdominal fat distribution and to determine critical levels of visceral adipose tissue (VAT) at those planes, exceeding which may lead to the development of type 2 diabetes. Methods Abdominal fat distribution was measured using computed tomography(CT) in 29 diabetics (19 male, 10 female) and 30 non-diabetics (18 male, 12 female). CT images obtained at two intervertebral locations L2-L3 and L4-L5 were used to measure the areas of total fat, VAT and subcutaneous adipose tissue (SCAT) using slice thickness of 5mm and an attenuation range from −190 to −30 Hounsfield units (HU). Data were analyzed using logistic regression and Receiver-operating characteristic (ROC) analysis. Results At L2-L3, diabetes and obesity were correctly classified at 91.53% and 83.05% respectively, while at L4-L5, the same were correctly classified at 84.75% and 88.14% respectively. VAT compared to SCAT, had significantly higher correctly classified percent values for predicting diabetes in both measurement sites. At L2-L3, VAT ≥ 177.29 cm 2 or VAT ≥ 51.52% of the total fat area had the highest correctly classified value for predicting diabetes in men, while VAT ≥ 132.27 cm 2 or VAT ≥ 45.7% of the total fat area had the highest correctly classified value for predicting diabetes in women. At L4-L5. VAT ≥ 130.82 cm 2 or VAT ≥ 45.54% of the total fat area had the highest correctly classified value for predicting diabetes in men, while VAT ≥ 118.56 cm 2 or VAT ≥ 32.24% of the total fat area had the highest correctly classified value for predicting diabetes in women. Conclusion L2-L3 plane is a better landmark for measuring abdominal fat distribution for predicting diabetes, while abdominal fat distribution measured at L4-L5 has better association with obesity. Regardless of the measurement site, VAT compared to SCAT, has significantly stronger association with diabetes.

11β‐Hydroxysteroid Dehydrogenase Type 1 mRNA is Increased in Both Visceral and Subcutaneous Adipose Tissue of Obese Patients

Data from rodents provide evidence for a causal role of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD-1) in the development of obesity and its complications. In humans, 11beta-HSD-1 is increased in subcutaneous adipose tissue (SAT) of obese patients, and higher adipose 11beta-HSD-1 was associated with features of the metabolic syndrome. To date, there is no evidence for an increased expression of 11beta-HSD-1 in human visceral adipose tissue (VAT), although VAT is the major predictor for insulin resistance and the metabolic syndrome. 11beta-HSD-1 and hexose-6-phosphate dehydrogenase (the enzyme responsible for the synthesis of nicotinamide adenine dinucleotide phosphate, the cofactor required for 11beta-HSD-1 oxoreductase activity) mRNA levels were measured using real-time quantitative reverse transcriptase-polymerase chain reaction in abdominal SAT and VAT biopsies obtained from 10 normal-weight and 12 obese women. Adiponectin mRNA was used as an internal control. 11beta-HSD-1 mRNA concentrations were significantly increased in both SAT and VAT of obese patients (720% and 450% of controls, respectively; p < 0.05) and correlated with hexose-6-phosphate dehydrogenase mRNA levels. The level of VAT 11beta-HSD-1 mRNA correlated with anthropometric parameters: BMI (r = 0.41, p = 0.05), waist circumference (r = 0.44, p = 0.04), abdominal sagittal diameter (r = 0.51, p = 0.02), and percentage fat (r = 0.51, p = 0.02). Our results demonstrate for the first time that 11beta-HSD-1 mRNA expression is increased in VAT from obese patients. They strengthen the importance of 11beta-HSD-1 in human obesity and its associated complications and suggest the need of clinical studies with specific 11beta-HSD-1 inhibitors.

Visceral obesity, impaired glucose tolerance, metabolic syndrome, and growth hormone therapy

Overweight adults with impaired glucose tolerance have a 5–10% risk of developing diabetes per year, and insulin resistance is an important cause of progression to diabetes in these individuals. Weight loss has been shown to improve insulin sensitivity and prevent or delay progression to diabetes. According to recent studies, the improvement in insulin sensitivity that occurs with weight loss is closely linked to the reduction of visceral adipose tissue (VAT), the collection of intra-abdominal adipose depots that includes omental and intrahepatic fat. After controlling for BMI, whole body fat, and subcutaneous fat, only VAT is an independent predictor of endogenous insulin sensitivity and glucose tolerance before or after weight loss. This, in turn, suggests that reducing VAT is crucial to improving insulin sensitivity and preventing diabetes in high-risk individuals. Recombinant human growth hormone (GH) is a lipolytic drug that reduces total body, abdominal, and visceral fat in growth hormone-deficient (GHD) adults. Several studies have reported substantial reductions in VAT following GH treatment in this population. Like GHD adults, abdominally obese individuals have increased VAT, insulin resistance, and growth hormone levels that are below normal during continuous 24-h monitoring. These similarities have prompted a number of recent investigations in abdominally obese adults that reported significant reductions in truncal and visceral fat and an improvement in insulin sensitivity following prolonged GH administration. However, other studies have shown that insulin resistance and glucose concentrations transiently worsen during the first few weeks of GH treatment and that these deleterious effects can persist even after VAT reduction has occurred. Prior studies involving GH treatment were generally limited to adults who were normoglycemic at baseline. Less is known about the effects of GH in adults with impaired glucose tolerance or diabetes. The effects of GH used in conjunction with insulin sensitizers on glycemic control and VAT in patients with impaired glucose tolerance will be reviewed.

The effect of abdominal obesity on insulin sensitivity and serum lipid and cytokine concentrations in African women

Studies have shown clear associations of abdominal obesity with lipid and glucose metabolism and cytokine levels in a number of different population groups. However, no such studies have been performed in an African population in which visceral adipose tissue levels have been shown to be lower than in European subjects. Cross-sectional analysis in 124 African women. Fasting serum samples were taken from all subjects and anthropometric measurements obtained. Blood levels of glucose, insulin, total cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, triglyceride, interleukin (IL)-6, IL-8 and IL-18 were measured. Subjects were separated into normal and abnormal glucose tolerant groups and into tertiles according to waist circumference (WC). Insulin resistance was assessed using the homeostasis model assessment (HOMA). Abnormal glucose-tolerant subjects had higher WC, glucose and HOMA levels than the normal glucose-tolerant group. Increased WC was associated with higher triglyceride, insulin and HOMA levels and lower HDL levels. Multiple regression analyses showed that WC associated positively with HOMA and serum triglyceride levels and negatively with HDL levels. IL18 was a positive but weak determinant of the HOMA level and BMI correlated positively with serum IL-6 concentrations. Although previous studies have shown that African subjects have a lower visceral adipose depot size than European subjects, abdominal obesity is still associated with insulin resistance and dyslipidaemia. The association between abdominal obesity and metabolic dysfunction within this population is not dependent upon IL-6, IL-8 or IL-18.

Visceral adipose tissue accumulation, secretory phospholipase A2-IIA and atherogenecity of LDL

The aim of the present study was to investigate the combined impact of visceral adipose tissue (VAT) and secretory group IIA phospholipase A(2) (sPLA(2)-IIA) concentrations on the atherogenicity of low-density lipoprotein (LDL) particles among men. Analyses were conducted in 74 mid-obese healthy men (age: (mean+/-s.d.) 37.9+/-11.7 years). Plasma levels of sPLA(2)-IIA were measured with a commercial ELISA and VAT levels were assessed by computed tomography. Distinct subpopulations of LDL particles were characterized from whole plasma using nondenaturating 2-16% gradient gel electrophoresis. Data indicated that plasma sPLA(2)-IIA levels were approximately 29% (P=0.007) higher among men characterized by a higher accumulation of VAT (>142 vs < or =142 cm(2)). Men having high plasma sPLA(2)-IIA levels (> or =127.2 ng/dl, the median value), were characterized by higher levels of plasma cholesterol (C) and apolipoprotein (apo) B, LDL-C, LDL-apoB, oxidized LDL (OxLDL) and by smaller LDL particles compared to men with sPLA(2)-IIA<127.2 ng/dl. Multiple regression analyses showed that plasma triglycerides and sPLA(2)-IIA levels explained 22.7 and 11.8% of the variance in LDL peak particle size, respectively. Levels of VAT and of sPLA(2)-IIA were the strongest correlates of OxLDL levels explaining, respectively, 15.0 and 5.5% of their variability. Both VAT and sPLA(2)-IIA levels modulate the atherogenecity of LDL by accounting for the reduction in their size and their susceptibility to oxidation.

Higher Content of Trans Fatty Acids in Abdominal Visceral Fat of Morbidly Obese Individuals undergoing Bariatric Surgery compared to Non-Obese Subjects

The purpose of this study was to determine the total content of trans fatty acids (TFA) in subcutaneous, retroperitoneal and visceral fat of morbidly obese and non-obese patients submitted to bariatric surgery or plastic and abdominal surgery. The adipose tissues were obtained by surgery; lipids were extracted, saponified and esterified. TFA were measured by FTIR-ATR spectroscopy. The TFA average in obese patients was 6.3% for retroperitoneal and 8.7% for visceral fat. For non-obese patients, the figures were 6.9% (subcutaneous) and 9.3% (visceral). There was no difference between the groups. However, the TFA depot in visceral fat was higher than other fatty tissues for morbidly obese (P<0.001) and non-obese (P<0.05) patients. Our values for TFA content in all adipose tissues analyzed are higher than reported in other countries (3-6%). We showed more TFA in visceral adipose tissue than in other abdominal fat (subcutaneous and retroperitoneal) stores. The visceral adipose tissue level is worrisome because the higher rate of lipolysis in this tissue appears to be an important indicator of metabolic alterations and the levels of TFA found in adipose tissue presumably reflect the higher dietary intake of TFA by Brazilians.

Ethnic Differences in Visceral Adipose Tissue and Type 2 Diabetes: Filipino, African‐American, and White Women

To compare ethnic differences in visceral adipose tissue (VAT), assessed by computed tomography, and type 2 diabetes risk among 55- to 80-year-old Filipino, African-American, and white women without known cardiovascular disease. Subjects were participants in the Rancho Bernardo Study (n = 196), the Filipino Women's Health Study (n = 181), and the Health Assessment Study of African-American Women (n = 193). Glucose and anthropometric measurements were assessed between 1995 and 2002. African-American women had significantly higher age-adjusted BMI (29.7 kg/m(2)) and waist girth (88.1 cm) compared with Filipino (BMI, 25.5 kg/m(2); waist girth, 81.9 cm) or white (BMI: 26.0 kg/m(2); waist girth: 80.7 cm) women. However, VAT was significantly higher among Filipino (69.1 cm(3)) compared with white (62.3 cm(3); p = 0.037) or African-American (57.5 cm(3), p < 0.001) women. VAT correlated better with BMI (r = 0.69) and waist (r = 0.77) in whites, compared with Filipino (r = 0.42; r = 0.59) or African-American (r = 0.50; r = 0.56) women. Age-adjusted type 2 diabetes prevalence was significantly higher in Filipinas (32.1%) than in white (5.8%) or African-American (12.1%) women. Filipinas had higher type 2 diabetes risk compared with African Americans [adjusted odds ratio, 2.30; 95% confidence interval (CI), 1.09 to 4.86] or whites (adjusted odds ratio, 7.51; 95% CI, 2.51 to 22.5) after adjusting for age, VAT, exercise, education, and alcohol intake. VAT was highest among Filipinas despite similar BMI and waist circumference as whites. BMI and waist circumference were weaker estimates of VAT in Filipino and African-American women than in whites. Type 2 diabetes prevalence was highest among Filipino women at every level of VAT, but VAT did not explain their elevated type 2 diabetes risk.

Relation of High-Sensitivity C-Reactive Protein, Interleukin-6, Tumor Necrosis Factor-Alpha, and Fibrinogen to Abdominal Adipose Tissue, Blood Pressure, and Cholesterol and Triglyceride Levels in Healthy Postmenopausal Women

The associations of inflammatory markers (high-sensitivity C-reactive protein [hs-CRP], interleukin-6 [IL-6], tumor necrosis factor-alpha, and fibrinogen) with anthropometric and metabolic variables were examined in a sample of 112 postmenopausal women not receiving hormone therapy. Body fat distribution was measured by computed tomography, and insulin sensitivity was determined by an euglycemic-hyperinsulinemic clamp. hs-CRP (0.10 < or = r(2) < or =0.37) and IL-6 (0.06 < or = r(2) < or =0.31) were significantly associated with anthropometric and metabolic variables, including visceral and subcutaneous adipose tissue, systolic and diastolic blood pressure, triglycerides, high-density lipoprotein (HDL) cholesterol, and insulin sensitivity (p <0.05). Women with greater hs-CRP concentrations showed deterioration in their metabolic risk profiles, including abdominal obesity, greater triglyceride and lower HDL cholesterol concentrations, and lower insulin sensitivity compared with women with lower hs-CRP levels. Fifty-nine percent of women with high hs-CRP concentrations had the metabolic syndrome as recently defined by the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. After adjustment for visceral adipose tissue, most of the differences in the plasma lipid-lipoprotein profile were eliminated between women with high hs-CRP levels and women with low hs-CRP levels, whereas some differences in blood pressure variables, insulin sensitivity, and inflammatory markers (IL-6 and fibrinogen) remained significant. In conclusion, these results suggest that increased visceral adipose tissue levels appear to be a determinant covariable of the association between high hs-CRP concentrations and alteration in the metabolic profile.

Apolipoprotein A-II polymorphism and visceral adiposity in African-American and white women.

To determine the association between the -265 T to C substitution in the apolipoprotein A-II (APOA-II) gene and levels of visceral adipose tissue (VAT) in a group of premenopausal African-American and white women, we genotyped 237 women (115 African-American and 122 white) for this polymorphism. Body composition was assessed by DXA, and VAT was determined from a single computed tomography scan. In addition to VAT, we examined the association between the polymorphism and other phenotypes (total body fat, total abdominal adipose tissue, and subcutaneous abdominal adipose tissue). The mutant C allele in the APOA-II gene was less frequent in African-American compared with white women, 23% vs. 36%, respectively (p < 0.01). VAT was significantly higher in carriers of the C allele compared with noncarriers after adjustment for total body fat (p < 0.05). When separate analyses by ethnic group were conducted, the association between the polymorphism and VAT was observed in white (p < 0.05) but not African-American (p = 0.57) women. There was no association between the polymorphism and the other phenotypes. These results indicate a significant association between the T265C APOA-II polymorphism and levels of VAT in premenopausal women. This association is present in white but not African-American women.

Adiponectinemia in Visceral Obesity: Impact on Glucose Tolerance and Plasma Lipoprotein and Lipid Levels in Men

The present study examined the associations between a major adipokine, adiponectin, and adiposity indices as well as metabolic risk variables in a sample of 190 untreated asymptomatic men. Anthropometric measurements and a complete fasting plasma lipoprotein and lipid profile were obtained, and subjects underwent an oral glucose tolerance test. Fasting plasma adiponectin concentrations were determined by an ELISA. Although all adiposity and adipose tissue (AT) distribution indices were negatively correlated with plasma adiponectin levels (-0.14 </= r </= -0.32; P < 0.04), multiple regression analyses revealed that visceral AT accumulation was the only independent predictor of adiponectin levels, with 10% of its variance explained by visceral AT (P < 0.0001). Comparison of obese men with similar body mass index values (>/=30 kg/m(2)) but who markedly differed in their level of visceral AT (< vs. >/=130 cm(2); n = 15) revealed significant differences in adiponectin levels (7.0 +/- 3.0 vs. 11.1 +/- 4.9 microg/ml; P < 0.02 for men with high vs. low visceral AT, respectively). Finally, when men were stratified into tertiles of visceral AT and further classified on the basis of the 50th percentile of adiponectin levels (</= vs. >8.8 microg/ml), a 3 x 2 ANOVA revealed an independent contribution of adiponectin on the variation of high-density lipoprotein cholesterol levels (P < 0.002) and of the glucose area (P < 0.02). These results support the notion that adiponectin concentration is influenced to a greater extent by visceral than sc obesity. Furthermore, adiponectin predicts glucose tolerance and plasma high-density lipoprotein cholesterol levels in a manner that is partly independent from the contribution of visceral adiposity.

The effects of low-dose growth hormone in HIV-infected men with fat accumulation: a pilot study.

Pharmacologic doses of growth hormone (GH) reduce HIV-associated fat accumulation but may worsen glucose metabolism. We investigated the effects of a low dose of GH (1 mg per day) in HIV-infected men with fat accumulation and found that such treatment reduced total fat and increased lean body mass without significant changes in glucose tolerance or insulin sensitivity. Visceral adipose tissue (VAT) levels did not change significantly for the group as a whole, although a reduction in the VAT level was seen in patients with a greater VAT level at baseline.

Effect of the factor VII R353Q missense mutation on plasma apolipoprotein B levels: impact of visceral obesity.

An atherogenic dyslipidemia, characterized by increased plasma triglyceride and apolipoprotein (apo) B levels, low HDL-cholesterol concentrations and the development of small, dense LDL particles has been associated with the presence of abdominal-visceral obesity. Visceral obesity is also associated with a hypercoagulate state and elevated concentrations of procoagulant factors such as factor VII. Moreover, it is known that some genetic variants in the gene encoding factor VII alter its activity and concentration, and consequently these variants may have an impact on atherosclerosis development. The objective of this study was to verify whether the factor VII R353Q polymorphism contributes to predict the risk of an atherogenic dyslipidemia in absence and in the presence of visceral obesity. A sample of 299 French-Canadian men, selected in order to cover a wide range of body fatness values, participated in this study. We observed that the R353 allele was more commonly observed among men characterized by apo B levels below 1.09 g/l than among men with apo B levels greater or above this threshold value (allele frequency of 92.1 vs 85.4%, chi(2)=6.18, P=0.01). Multivariate analyses further showed that the genotype R353/R353 was associated with a lower risk to exhibit atherogenic concentrations of total-apo B (>/=1.09 g/l) and LDL apo B (>/=0.95 g/l) before (odds ratio:0.47, 95%CI=0.27-0.90, P=0.02; odds ratio:0.46, 95%CI=0.25-0.85, P=0.01, respectively) and after adjustments for age and visceral AT (odds ratio:0.49, 95%CI=0.24-0.91, P=0.02; odds ratio:0.44, 95%CI=0.23-0.85, P=0.01, respectively). When the two genotype groups were further divided on the basis of visceral adipose tissue (AT) accumulation using a cutoff point of 130 cm(2), we observed that R353/R353 homozygotes with low visceral AT were characterized by a more favorable lipoprotein-lipid profile, mainly lower total-cholesterol, total-apo B, and LDL-apo B levels compared with R353/R353 homozygotes with high levels of visceral AT. In contrast, irrespective of obesity, plasma lipid levels among carriers of the Q353 allele were similar to those of viscerally obese men homozygous for the R353 allele. In conclusion, results of the present study suggest that the factor VII R353 allele is associated with lower concentrations of plasma apo B levels. However, the presence of visceral obesity abolishes this effect. Further studies will be necessary to confirm this association and the mechanism involved.

Is there a threshold of visceral fat loss that improves the metabolic profile in obese postmenopausal women?

It is presently unclear how much visceral adipose tissue (VAT) loss is needed to induce favorable metabolic changes. Cross-sectional studies have proposed that a threshold level of VAT exceeding 110 cm2 in women induces deleterious changes in the metabolic profile. It is presently unclear, however, if significant decreases in VAT below this given threshold significantly improve the metabolic profile more as compared to decreases that remain below 110 cm2. To examine whether achieving versus not achieving the proposed VAT threshold impacts differently on the metabolic profile in postmenopausal women, we examined the effects of a VAT loss below the 110-cm2 threshold versus those individuals who remained higher than 110 cm2 after a weight loss program. Twenty-five sedentary obese (baseline % body fat, 47.7% ± 4.1%; [mean ± SD]) postmenopausal women aged between 51 and 71 years (59.7 ± 5.6 years) and displaying high baseline levels of VAT accumulation (223 ± 45 cm2) were submitted to a 1-year weight loss program with weight stabilization periods before and after weight reduction. Based on their loss of VAT after weight loss, subjects were characterized as “attainers” (post VAT levels < 110 cm2; average, 96 ± 10 cm2; n = 10) or “non-attainers” (post VAT levels > 110 cm2; average, 171 ± 34 cm2; n = 15). We compared changes in (1) plasma lipid-lipoprotein levels, (2) insulin sensitivity (euglycemic/hyperinsulinemic clamp), and (3) supine resting blood pressure between groups who achieved these 2 distinct levels of VAT. Attainers showed a 2-fold greater loss of VAT compared to non-attainers (−51.5% v −27.5%, P <.001). Attainers also showed a greater loss of body weight (−19.0% v −12.5%, P <.01) and fat mass (−34.8% v −18.4%, P <.001) after the program compared to non-attainers. Despite significant differences in the loss of total fat and VAT after the weight loss program, attainers and non-attainers showed comparable improvements for plasma high-density lipoprotein-cholesterol (HDL-chol) levels (+62.5% v +50.0%, P = not significant [NS]), cholesterol/HDL-chol ratio (−45.5% v −36.5%, P = NS), insulin sensitivity (+34.1% v +23.2%, P = NS), and resting systolic (−6.9% v −5.1%, P = NS) and diastolic (−11.3% v −11.1%, P = NS) blood pressure. These results do not favor the idea that attaining levels of VAT below a threshold of 110 cm2 is necessary to favorably improve the metabolic profile in obese postmenopausal women. Achieving or not the proposed threshold of VAT, independently of baseline values, appears to yield similar metabolic improvements in obese postmenopausal women. More moderate losses of VAT appear to yield similar metabolic improvements as large losses. © 2003 Elsevier Inc. All rights reserved.

Visceral adipose tissue cutoffs associated with metabolic risk factors for coronary heart disease in women.

This study determined whether there is a critical level of visceral adipose tissue (VAT) associated with elevated coronary heart disease (CHD) risk factors in a cohort of women >45 years of age. Measurements of body composition (dual-energy X-ray absorptiometry), body fat distribution (computed tomography), fasting and 2-h postprandial (75-g) glucose concentrations, and fasting lipoprotein lipid and insulin concentrations were performed in 233 perimenopausal (9%) and postmenopausal women (age 59 +/- 6 years, 79% Caucasian, 16% on hormone replacement therapy). Women in the lowest VAT quintile (< or =105 cm(2)) had higher concentrations of HDL and HDL(2) cholesterol, lower LDL/HDL cholesterol ratios and triglyceride concentrations, and lower fasting glucose and insulin concentrations than women in the remaining four quintiles (P values <0.05-0.001). Women in the second lowest VAT quintile (106-139 cm(2)) had higher HDL and HDL(2) cholesterol and lower LDL/HDL ratios than women with a VAT > or =163 cm(2) (P < 0.05). Logistic regression analyses showed that women with a VAT of 106-162 cm(2) are 2.5 times more likely to have a low HDL cholesterol (P < 0.05), while women with a VAT > or =163 cm(2) are 5.5 times more likely to have a low HDL cholesterol (P < 0.01) and approximately 4.0 times more likely to have a high LDL/HDL ratio (P < 0.05) compared with women with a VAT < or =105 cm(2). Women with a VAT > or =163 cm(2) are at a higher risk of having impaired glucose tolerance (P < 0.01). A VAT > or =106 cm(2) is associated with an elevated risk, and a VAT > or =163 cm(2) with an even greater risk, for these metabolic CHD risk factors compared with women with a VAT < or =105 cm(2). These values may prove useful for defining "visceral obesity" and for identifying women most likely to benefit from preventative interventions.

Visceral adipose tissue in women: longitudinal study of the effects of fat gain, time, and race.

To determine the effects of fat gain, time, and race on the accumulation of visceral adipose tissue (VAT) in a group of normal-weight premenopausal women. Sixty-five women participated in the study (32 African American and 33 white). The mean age of subjects was 34 +/- 6 years (range, 22 to 47 years). Eligible subjects were women who had body mass indices <25 kg/m(2) at baseline and who had completed evaluations at baseline and at follow-up year 1, without intervention. A subset of subjects was reevaluated annually for up to 4 years. Body composition was assessed by DXA, and VAT was determined from a single computed tomography scan. A linear mixed model was used to examine changes in VAT over time, with total body fat as a covariate Total fat mass was not significantly different between races at baseline and increased significantly in both groups over time (p < 0.001). Time-related increases in total body fat were greater in African-American women (p < 0.01). VAT was significantly higher in white women at baseline (p < 0.01) and increased significantly over time in both races (p < 0.01), but remained higher in white women (p < 0.001). Increases in VAT, relative to total body fat, were greater than the increases in total body fat over time, independent of age and race (p < 0.001). Gaining total body-fat mass results in a higher increase in VAT, relative to total body fat, regardless of race and age, although African-American women maintain a lower VAT levels across time.

Visceral obesity and hyperinsulinemia modulate the impact of the microsomal triglyceride transfer protein −493G/T polymorphism on plasma lipoprotein levels in men

The dyslipidemic state of visceral obesity is characterized by increased plasma triglyceride levels, low high-density lipoprotein-cholesterol concentration and alterations in low-density lipoprotein (LDL) composition and concentration. A functional, non-coding microsomal triglyceride transfer protein (MTP) −493G/T polymorphism of the microsomal triglyceride transfer protein gene has been related to variations in LDL-cholesterol levels. To study the effect of the MTP −493G/T polymorphism on lipoprotein levels in visceral obesity and hyperinsulinemia, a total of 227 men were assigned into two groups on the basis of their MTP −493G/T polymorphism, including 121 GG homozygotes and 105 carriers of the T allele (92 GT and 13 TT). The two genotypic groups did not differ for their physiological characteristics nor for lipoprotein–lipid profiles, before and after adjustment for age. However, GG homozygotes were characterized by higher fasting insulin levels than carriers of the T allele ( P<0.05). When the two genotypic groups were further divided on the basis of their visceral adipose tissue (AT) accumulation, assessed by computed tomography, we observed that T allele carriers with low levels of visceral AT (<130 cm 2) had decreased plasma total cholesterol and LDL-apolipoprotein B (LDL-apoB) levels compared to viscerally obese men ( P=0.035 and P=0.0001, respectively). Among GG homozygotes, no significant difference were observed. Although not significant, T allele carriers characterized by visceral obesity tended to have smaller, denser LDL particles than T allele carriers characterized by a low accumulation of visceral AT. When subjects were divided on the basis of their fasting insulin levels, it appears that hyperinsulinemic men were characterized by a deteriorated lipoprotein–lipid profile when they were carriers of the T allele compared to normoinsulinemic men. In summary, visceral obesity and hyperinsulinemia modulate the impact of the MTP −493G/T polymorphism on plasma total cholesterol and LDL-apoB levels, as well as on LDL peak particle diameter.

Reduced HDL particle size as an additional feature of the atherogenic dyslipidemia of abdominal obesity

Reduced plasma HDL cholesterol concentration has been associated with an increased risk of coronary heart disease. However, a low HDL cholesterol concentration is usually not observed as an isolated disorder because this condition is often accompanied by additional metabolic alterations. The objective of this study was to document the relevance of assessing HDL particle size as another feature of the atherogenic dyslipidemia found among subjects with visceral obesity and insulin resistance. For that purpose, an average HDL particle size was computed by calculating an integrated HDL particle size using nondenaturing 4-30% gradient gel electrophoresis. Potential associations between this average HDL particle size versus morphometric and metabolic features of visceral obesity were examined in a sample of 238 men. Results of this study indicated that HDL particle size was a significant correlate of several features of an atherogenic dyslipidemic profile such as increased plasma TG, decreased HDL cholesterol, high apolipoprotein B, elevated cholesterol/HDL cholesterol ratio, and small LDL particles as well as increased levels of visceral adipose tissue (AT) (0.33 < or = absolute value of r < or = 0.61, P < 0.0001). Thus, men with large HDL particles had a more favorable plasma lipoprotein-lipid profile compared with those with smaller HDL particles. Furthermore, men with large HDL particles were also characterized by reduced overall adiposity and lower levels of visceral AT as well as reduced insulinemic-glycemic responses to an oral glucose load. In conclusion, small HDL particle size appears to represent another feature of the high TG- low HDL cholesterol dyslipidemia found in viscerally obese subjects characterized by hyperinsulinemia.