Body Compartment and Subcutaneous Adipose Tissue Distribution - Risk Factor Patterns in Obese Subjects

The purpose of this study was to investigate whether upper body obesity and/or visceral obesity are related to cardiovascular risk factors among severely obese subjects, phenomena that have previously been reported in more heterogeneous body weight distri -buttons. 2450 severely obese men and women aged 37 to 59 years, with a body mass index of 39 ± 4.5 kg/m² (mean ± SD) were examined cross-sectionally. Eight cardiovascular risk factors were studied in relation. to the following body composition indicators: four trunk and three limb circumferences, along with weight, height and sagittal trunk diameter. From the latter three measurements lean body mass (LBM, i.e., the non-adipose tissue mass) and the masses of subcutaneous and visceral adipose tissue were estimated by using sex-specific prediction equations previously calibrated by computed tomography. Two risk factor patterns could be distinguished: 1. One body compartment- risk factor pattern in which the subcutaneous adipose tissue (AT) mass and, in particular, the visceral AT mass were positively related to most risk factors while the lean body mass was negatively related to some risk factors. 2. One subcutaneous adipose tissue distribution- risk factor pattern in which the neck circumference was positively and the thigh circumference negatively related to several risk factors. It is concluded that lean body mass (LBM), visceral and subcutaneous adipose tissue masses as well as neck and thigh circumferences, used as indices of subcutaneous adipose tissue distribution, are independently related to cardiovascular risk factors in severely obese men and women.     

Growth of Visceral Fat,Subcutaneous Abdominal Fat,and Total Body Fat in Children

Objective: To examine the patterns of growth of visceral fat, subcutaneous abdominal fat, and total body fat over a 3‐ to 5‐year period in white and African American children. Research Methods and Procedures: Children (mean age: 8.1 ± 1.6 years at baseline) were recruited from Birmingham, Alabama, and those with three or more repeated annual measurements were included in the analysis (N = 138 children and 601 observations). Abdominal adipose tissue (visceral and subcutaneous) was measured using computed tomography. Total body fat and lean tissue mass were measured by DXA. Random growth curve modeling was performed to estimate growth rates of the different body fat compartments. Results: Visceral fat and total body fat both exhibited significant growth effects before and after adjusting for subcutaneous abdominal fat and lean tissue mass, respectively, and for gender, race, and baseline age (5.2 ± 2.2 cm²/yr and 1.9 ± 0.8 kg/yr, respectively). After adjusting for total body fat, the growth of subcutaneous abdominal fat was not significant. Whites showed a higher visceral fat growth than did African Americans (difference: 1.9 ± 0.8 cm²/yr), but there was no ethnic difference for growth of subcutaneous abdominal fat or total body fat. There were no gender differences found for any of the growth rates. Discussion: Growth of visceral fat remained significant after adjusting for growth of subcutaneous abdominal fat, implying that the acquisition of the two abdominal fat compartments may involve different physiologic mechanisms. In contrast, growth of subcutaneous abdominal fat was explained by growth in total body fat, suggesting that subcutaneous fat may not be preferentially deposited in the abdominal area during this phase of growth. Finally, significantly higher growth of visceral fat in white compared with African American children is consistent with cross‐sectional findings.     

Higher Free Fatty Acid Uptake in Visceral Than in Abdominal Subcutaneous Fat Tissue in Men

Visceral adipose tissue has been shown to have high lipolytic activity. The aim of this study was to examine whether free fatty acid (FFA) uptake into visceral adipose tissue is enhanced compared to abdominal subcutaneous tissue in vivo. Abdominal adipose tissue FFA uptake was measured using positron emission tomography (PET) and [¹⁸F]‐labeled 6‐thia‐hepta‐decanoic acid ([¹⁸F]FTHA) and fat masses using magnetic resonance imaging (MRI) in 18 healthy young adult males. We found that FFA uptake was 30% higher in visceral compared to subcutaneous adipose tissue (0.0025 ± 0.0018 vs. 0.0020 ± 0.0016 µmol/g/min, P = 0.005). Visceral and subcutaneous adipose tissue FFA uptakes were strongly associated with each other (P < 0.001). When tissue FFA uptake per gram of fat was multiplied by the total tissue mass, total FFA uptake was almost 1.5 times higher in abdominal subcutaneous than in visceral adipose tissue. In conclusion, we observed enhanced FFA uptake in visceral compared to abdominal subcutaneous adipose tissue and, simultaneously, these metabolic rates were strongly associated with each other. The higher total tissue FFA uptake in subcutaneous than in visceral adipose tissue indicates that although visceral fat is active in extracting FFA, its overall contribution to systemic metabolism is limited in healthy lean males. Our results indicate that subcutaneous, rather than visceral fat storage plays a more direct role in systemic FFA availability. The recognized relationship between abdominal visceral fat mass and metabolic complications may be explained by direct effects of visceral fat on the liver.     

Visceral and Subcutaneous Adipose Tissue Diacylglycerol Acyltransferase Activity in Humans

Diacylglycerol acyltransferase (DGAT) could be a rate limiting step in triglyceride (TG) synthesis as it is the final step in this pathway. As such, between depot differences in DGAT activity could influence regional fat storage. DGAT activity and in vitro rates of direct free fatty acid (FFA) storage were measured in abdominal subcutaneous and omental adipose tissue samples from 12 nonobese (BMI <30 kg/m²) and 23 obese men and women (BMI >30 kg/m²) undergoing elective surgery. DGAT activity was greater in omental than in abdominal subcutaneous adipose tissue from nonobese patients (2.0 ± 0.9 vs. 0.9 ± 0.3 pmol/min/mg lipid, respectively, P = 0.003), but not from obese patients (1.4 ± 0.6 vs. 1.7 ± 0.7 pmol/min/mg lipid, respectively, P = 0.10). DGAT activity per unit adipose weight was negatively correlated with adipocyte size (P < 0.01) and positively correlated with direct FFA storage in omental (P < 0.001) but not in abdominal subcutaneous fat. Tissue DGAT activity varies as a function of adipocyte size, but this relationship differs between visceral and abdominal subcutaneous fat in obese and nonobese humans. Our results are consistent with the hypothesis that interindividual variations in DGAT activity may be an important regulatory step in visceral adipose tissue FFA uptake/storage.     

Associations among SPARC mRNA expression in adipose tissue,serum SPARC concentration and metabolic parameters in Korean women

Objective: Secreted protein acidic and rich in cysteine (SPARC) is expressed in most tissues and is also secreted by adipocytes. The associations of SPARC mRNA expression in visceral adipose tissue (VAT), subcutaneous abdominal adipose tissue (SAT), serum SPARC concentration, and metabolic parameters in Korean women are investigated. Design and Methods: This is a cross‐sectional study. Fifty‐eight women were recruited, of whom 15 women who underwent bariatric surgery for morbid obesity (BMI mean ± SD: 40.2±5.7 kg/m²), 16 who underwent metabolic surgery for type 2 diabetes (BMI: 28.9±4.5 kg/m²), and, as a control group, 27 who underwent gynecological surgery (BMI: 22.7±2.4 kg/m²). Anthropometric variables, metabolic parameters, SPARC mRNA expression in adipose tissue, and serum SPARC concentration were measured. Results: In all subjects, SPARC mRNA expression was significantly higher in SAT than in VAT. Serum SPARC concentrations (mean ± SE) in morbidly obese subjects, subjects with type 2 diabetes, and normal weight subjects were 267.3±40.2 ng/mL, 130.4±33.0 ng/mL, and 53.1±2.8 ng/mL, respectively. SPARC mRNA in SAT was significantly correlated with BMI, whereas SPARC mRNA in VAT was significantly correlated with BMI and VAT area. Serum SPARC concentration was significantly correlated with BMI, waist circumference, total adipose tissue area, and SAT area. After BMI adjustment, serum SPARC concentration was significantly correlated with fasting insulin concentration and HOMA‐IR score. Multivariate regression analysis showed that BMI and HOMA‐IR were independently associated with serum SPARC concentration. Conclusions: Serum SPARC concentration is significantly correlated with obesity indices and might be influenced by insulin resistance. These findings suggest that SPARC may contribute to the metabolic dysregulation associated with obesity in humans.     

Reduction of Visceral Adipose Tissue and Improvement of Metabolic Indices: Effect of Dexfenfluramine in NIDDM

Increased visceral adipose tissue is thought to contribute to impaired glucose tolerance. We studied 10 men with non-insulin dependent diabetes (NIDDM) before and after a 12-week intervention study using dexfenfluramine. Subjects had a mean body mass index (BMI) of 26.4 ± 1.7 kg\m² and had an abdominal distribution of body fatness (waist-to hip ratio >0.9). Anthropometric indices, biochemistry, macronutrient intake from 7-day food records as well as a euglycaemic glucose clamp and magnetic resonance imaging (MRI) were performed at week 0 and week 12. Abdominal adipose tissue area measured by MRI was reduced from 854 ± 270 cm² to 666 ± 231 cm² (p=0.003) due mainly to a selective 32% reduction in visceral fat area from 484 ± 230 cm² to 333 ± 72 cm² (p=0.002). Insulin sensitivity improved from 0.29 ± 0.13 [min^?1 (mU/L)] to 0.54 ± 0.21 [min^?1 (mU/L)] (p=0.01) and C-peptide levels reduced from 0.77 ± 0.24 μmol/L to 0.58 ± 0.15 μmol/L (p=0.002). The reductions in fasting glucose and glycated haemoglobin failed to achieve significance. Fasting total cholesterol and triglyceride levels significantly reduced (p=<0.001 and p=0.021 respectively). There was a reduction in total energy intake (p=0.005) due to a significant reduction in calories obtained from fat (p<0.001). Thus dexfenfluramine was shown to be a useful adjunct therapy for the reduction of visceral fat in abdominally-obese men with NIDDM with an associated improvement in insulin sensitivity.     

Abdominal Adipose Tissue was Associated with Glomerular Hyperfiltration among Non- Diabetic and Normotensive Adults with a Normal Body Mass Index

Glomerular hyperfiltration is recognized as an early marker of progressive kidney dysfunction in the obese population. This study aimed to identify the relationship between glomerular hyperfiltration and body fat distribution measured by computed tomography (CT) in healthy Korean adults. The study population included individuals aged 20–64 years who went a routine health check-up including an abdominal CT scan. We selected 4,378 individuals without diabetes and hypertension. Glomerular filtration rate was estimated using the CKD-EPI equation, and glomerular hyperfiltration was defined as the highest quintile of glomerular filtration rate. Abdominal adipose tissue areas were measured at the level of the umbilicus using a 16-detector CT scanner, and the cross-sectional area was calculated using Rapidia 2.8 CT software. The prevalence of glomerular hyperfiltration increased significantly according to the subcutaneous adipose tissue area in men (OR = 1.74 (1.16–2.61), P for trend 0.016, for the comparisons of lowest vs. highest quartile) and visceral adipose tissue area in women (OR = 2.34 (1.46–3.75), P for trend < 0.001) in multivariate analysis. After stratification by body mass index (normal < 23 kg/m², overweight ≥ 23 kg/m²), male subjects with greater subcutaneous adipose tissue, even those in the normal BMI group, had a higher prevalence of glomerular hyperfiltration (OR = 2.11 (1.17–3.80), P for trend = 0.009). Among women, the significance of visceral adipose tissue area on glomerular hyperfiltration resulted from the normal BMI group (OR = 2.14 (1.31–3.49), P for trend = 0.002). After menopause, the odds ratio of the association of glomerular hyperfiltration with subcutaneous abdominal adipose tissue increased (OR = 2.96 (1.21–7.25), P for trend = 0.013). Subcutaneous adipose tissue areas and visceral adipose tissue areas are positively associated with glomerular hyperfiltration in healthy Korean adult men and women, respectively. In post-menopausal women, visceral adipose tissue area shows significant positive association with glomerular hyperfiltration as in men.     

Subdivision of the Subcutaneous Adipose Tissue Compartment and Lipid‐Lipoprotein Levels in Women

Objective: The aim of this study was to compare the relative importance of computed tomography‐measured abdominal fat compartment areas, including adipose tissue located posterior to the subcutaneous Fascia, in predicting plasma lipid‐lipoprotein alterations. Research Methods and Procedures: Areas of visceral as well as subcutaneous deep and superficial abdominal adipose tissue were measured by computed tomography in a sample of 66 healthy women, ages 37 to 60 years, for whom a detailed lipid‐lipoprotein profile was available. Results: Strong significant associations were observed between visceral adipose tissue area and most variables of the lipid‐lipoprotein profile (r = ?0.25, p < 0.05 to 0.62, p < 0.0001). Measures of hepatic lipoprotein synthesis such as very‐low‐density lipoprotein‐triglyceride and cholesterol content as well as total and very‐low‐density lipoprotein‐apolipoprotein B levels were also strongly associated with visceral adipose tissue area (r = 0.57, 0.57, 0.61, and 0.62, respectively, p < 0.0001). Significant associations were found between these variables and the deep subcutaneous adipose tissue area or DXA‐measured total body fat mass. However, the correlation coefficients were of lower magnitude compared to those with visceral adipose tissue area. Multivariate regression analyses demonstrated that visceral adipose tissue area was the strongest predictor of lipid‐lipoprotein profile variables (7% to 48% explained variance, 0.02 ≥ p ≤ 0.0001). Discussion: Although previous studies have generated controversial data as to which abdominal adipose tissue compartment was more closely associated with insulin resistance, our results suggest that visceral adipose tissue area is a stronger correlate of other obesity‐related outcomes such as lipid‐lipoprotein alterations.     

Two-dimensional predictive equation to classify visceral obesity in clinical practice

Objective: Visceral obesity assessment is not easy, and although computed tomography (CT) is an accurate tool, this technique is expensive and sometimes not suitable in clinical practice. We developed a new two‐dimensional elliptical anthropometric equation to classify visceral obesity and evaluated the validity and the reliability of the new equation compared with CT. Research Methods and Procedures: We collected anthropometric and CT data from overweight/obese subjects (n = 61, BMI = 32.4 ± 3.7 kg/m²). A validation group of 32 subjects was also selected. An equation for the assessment of visceral obesity was developed using multiple regression analysis. Once validated, the equation was compared with previous models. Tests for accuracy included mean differences, analysis of diagnostic, R², Snedecor's F‐test, and Bland‐Altman plot. Results: Multiple regression analysis revealed that the sagittal and coronal diameters and the triceps skinfold were significant contributors to the model. The final equation was: visceral area (VA)/subcutaneous area (SA)_predicted = 0.868 + 0.064 × sagittal diameter ?0.036 × coronal diameter ?0.022 × triceps skinfold. Patients with visceral‐subcutaneous area ratio (VA/SA) >0.42 were classified as having visceral obesity. The predictive equation was valid, showing a significant association with VA/SA assessed by CT (VA/SA_CT; r = 0.68; p < 0.0001). Paired Student's t test showed no significant differences with VA/SA_CT (p = 0.541). The reliability was high [F(24/60) = 2.12; p = 0.01]. Discussion: The new two‐dimensional and elliptical predictive equation is valid to assess visceral obesity and is more precise than previous models.     

Validation of an Elliptical Anthropometric Model to Estimate Visceral Compartment Area

Objective: The visceral compartment is a surrogate for visceral adipose tissue. Cross‐sectional visceral compartment area (VCA) has been approximated from waist circumference using a circular model. However, the two‐dimensional shape of the abdomen is rarely circular. This study validated an elliptical model of cross‐sectional total abdominal area (TAA), subcutaneous adipose tissue (SAT) area, and VCA at the L₄–L₅ level. Research Methods and Procedures: We analyzed magnetic resonance images (MRIs) at the level of the L₄–L₅ intervertebral space from 35 subjects with a wide range of abdominal adiposity. Waist circumference, abdominal thickness (midline sagittal diameter), abdominal width (coronal diameter at one‐half of abdominal thickness), and abdominal SAT thickness at four sites (front, back, right, and left) were measured from MRI images using an image analysis software. The same anatomical regions were also estimated from anthropometrics purely by geometric formulae of circular and elliptical models. A simple linear regression model was used to interpret the association strength between anthropometric estimates and MRI measures. Results: Estimated TAA by either model was strongly related to MRI TAA (r² = 0.98, p < 0.0001). The SAT and VCA by MRI analysis showed a stronger association with calculation from an elliptical model (r² = 0.95 and 0.88, respectively; p < 0.001) than a circular model (r² = 0.69 and 0.25, respectively; p < 0.001). The absolute prediction residuals and variances were significantly smaller with an elliptical model than a circular model (p < 0.0001). Discussion: An elliptical anthropometric model might be superior to a circular model to estimate abdominal SAT and VCA.     

Omental adipocyte hypertrophy relates to coenzyme Q10 redox state and lipid peroxidation in obese women

Occurrence of oxidative stress in white adipose tissues contributes to its dysfunction and the development of obesity-related metabolic complications. Coenzyme Q10 (CoQ10) is the single lipophilic antioxidant synthesized in humans and is essential for electron transport during mitochondrial respiration. To understand the role of CoQ10 in adipose tissue physiology and dysfunction, the abundance of the oxidized and reduced (CoQ10_red) isoforms of the CoQ10 were quantified in subcutaneous and omental adipose tissues of women covering the full range of BMI (from 21.5 to 53.2 kg/m²). Lean women displayed regional variations of CoQ10 redox state between the omental and subcutaneous depot, despite similar total content. Obese women had reduced CoQ10_red concentrations in the omental depot, leading to increased CoQ10 redox state and higher levels of lipid hydroperoxide. Women with low omental CoQ10 content had greater visceral and subcutaneous adiposity, increased omental adipocyte diameter, and higher circulating interleukin-6 and C-reactive protein levels and were more insulin resistant. The associations between abdominal obesity-related cardiometabolic risk factors and CoQ10 content in the omental depot were abolished after adjustment for omental adipocyte diameter. This study shows that hypertrophic remodeling of visceral fat closely relates to depletion of CoQ10, lipid peroxidation, and inflammation.     

Relationships among body composition measures in community-dwelling older women

Objective: To examine whether simple anthropometric measures provide a good estimate of total and visceral fat in 146 community‐dwelling, older white women (mean age, 74.0 ± 4.1 years). Research Methods and Procedures: Total body fat and visceral fat were measured using electron beam computed tomography (EBT). Anthropometric parameters (height, weight, BMI, sagittal diameter, and waist circumference) were measured using standard techniques. Total percentage body fat was assessed using DXA. Spearman correlations were used to examine the association between the measures. Linear regression, controlling for age, was used to examine the associations between the anthropometric parameters and total and visceral body fat measured by EBT. Results: Correlations among body composition measures ranged from ρ = 0.46 to 0.93 (p < 0.0001). EBT total fat was strongly correlated with both DXA estimates of total percentage fat (ρ = 0.86) and BMI (ρ = 0.89). Separate linear regression models indicated that BMI, waist circumference, sagittal diameter, and DXA total percentage fat were each independently related to EBT total fat. BMI had the strongest linear relationship, explaining 80% of the model variance (p < 0.0001). Linear regression indicated that BMI, waist circumference, and sagittal diameter were each independently related to EBT visceral fat, with BMI and sagittal diameter explaining ～53% of the model variance (p < 0.0001). Discussion: The use of simple anthropometric measures such as BMI, sagittal diameter, and waist circumference may be an appropriate alternative for more expensive techniques when assessing total fat but should be used with caution when estimating visceral body fat.     

Differential patterns of serum concentration and adipose tissue expression of chemerin in obesity: Adipose depot specificity and gender dimorphism

Chemerin, a recognized chemoattractant, is expressed in adipose tissue and plays a role in adipocytes differentiation and metabolism. Gender- and adipose tissue-specific differences in human chemerin expression have not been well characterized. Therefore, these differences were assessed in the present study. The body mass index (BMI) and the circulating levels of chemerin and other inflammatory, adiposity and insulin resistance markers were assessed in female and male adults of varying degree of obesity. Chemerin mRNA expression was also measured in paired subcutaneous and visceral adipose tissue samples obtained from a subset of the study subjects. Serum chemerin concentrations correlated positively with BMI and serum leptin levels and negatively with high density lipoprotein (HDL)-cholesterol levels. No correlation was found between serum chemerin concentrations and fasting glucose, total cholesterol, low density lipoprotein (LDL)-cholesterol, triglycerides, insulin, C-reactive protein or adiponectin. Similarly, no relation was observed with the homeostasis model assessment for insulin resistance (HOMA-IR) values. Gender- and adipose tissue-specific differences were observed in chemerin mRNA expression levels, with expression significantly higher in women than men and in subcutaneous than visceral adipose tissue. Interestingly, we found a significant negative correlation between circulating chemerin levels and chemerin mRNA expression in subcutaneous fat. Among the subjects studied, circulating chemerin levels were associated with obesity markers but not with markers of insulin resistance. At the tissue level, fat depot-specific differential regulation of chemerin mRNA expression might contribute to the distinctive roles of subcutaneous vs. visceral adipose tissue in human obesity.     

VAT=TAAT‐SAAT: Innovative anthropometric model to predict visceral adipose tissue without resort to CT‐Scan or DXA

Objective:

To investigate whether a combination of a selected but limited number of anthropometric measurements predicts visceral adipose tissue (VAT) better than other anthropometric measurements, without resort to medical imaging.

Hypothesis:

Abdominal anthropometric measurements are total abdominal adipose tissue indicators and global measures of VAT and SAAT (subcutaneous abdominal adipose tissue). Therefore, subtracting the anthropometric measurement the more correlated possible with SAAT while being the least correlated possible with VAT, from the most correlated abdominal anthropometric measurement with VAT while being highly correlated with TAAT, may better predict VAT.

Design and Methods:

BMI participants' range was from 16.3 to 52.9 kg m^?2. Anthropometric and abdominal adipose tissues data by computed tomography (CT‐Scan) were available in 253 patients (18‐78 years) (CHU Nord, Marseille) and used to develop the anthropometric VAT prediction models.

Results:

Subtraction of proximal thigh circumference from waist circumference, adjusted to age and/or BMI, predicts better VAT (Women: VAT = 2.15 × Waist C ? 3.63 × Proximal Thigh C + 1.46 × Age + 6.22 × BMI ? 92.713; R² = 0.836. Men: VAT = 6 × Waist C ? 4.41 × proximal thigh C + 1.19 × Age ? 213.65; R² = 0.803) than the best single anthropometric measurement or the association of two anthropometric measurements highly correlated with VAT. Both multivariate models showed no collinearity problem. Selected models demonstrate high sensitivity (97.7% in women, 100% in men). Similar predictive abilities were observed in the validation sample (Women: R² = 76%; Men: R² = 70%). Bland and Altman method showed no systematic estimation error of VAT.

Conclusion:

Validated in a large range of age and BMI, our results suggest the usefulness of the anthropometric selected models to predict VAT in Europides (South of France).

     

Exercise‐Induced Reduction in Obesity and Insulin Resistance in Women: a Randomized Controlled Trial

Objectives : To determine the effects of equivalent diet‐ or exercise‐induced weight loss and exercise without weight loss on subcutaneous fat, visceral fat, and insulin sensitivity in obese women. Research Methods and Procedures : Fifty‐four premenopausal women with abdominal obesity [waist circumference 110.1 ± 5.8 cm (mean ± SD)] (BMI 31.3 ± 2.0 kg/m²) were randomly assigned to one of four groups: diet weight loss (n = 15), exercise weight loss (n = 17), exercise without weight loss (n = 12), and a weight‐stable control group (n = 10). All groups underwent a 14‐week intervention. Results : Body weight decreased by ～6.5% within both weight loss groups and was unchanged in the exercise without weight loss and control groups. In comparison with controls, cardiorespiratory fitness improved within the exercise groups only (p < 0.01). Reduction in total, abdominal, and abdominal subcutaneous fat within the exercise weight loss group was greater (p < 0.001) than within all other groups. The reduction in total and abdominal fat within the diet weight loss and exercise without weight loss groups was greater than within controls (p < 0.001) but not different from each other (p > 0.05). Visceral fat decreased within all treatment groups (p < 0.008), and these changes were not different from each other. In comparison with the control group, insulin sensitivity improved within the exercise weight loss group alone (p < 0.001). Discussion : Daily exercise without caloric restriction was associated with substantial reductions in total fat, abdominal fat, visceral fat, and insulin resistance in women. Exercise without weight loss was also associated with a substantial reduction in total and abdominal obesity.     

Fat Depot‐specific Impact of Visceral Obesity on Adipocyte Adiponectin Release in Women

Our objective was to examine omental and subcutaneous adipocyte adiponectin release in women. We tested the hypothesis that adiponectin release would be reduced to a greater extent in omental than in subcutaneous adipocytes of women with visceral obesity. Omental and subcutaneous adipose tissue samples were obtained from 52 women undergoing abdominal hysterectomies (age: 47.1 ± 4.8 years; BMI: 26.7 ± 4.7 kg/m²). Adipocytes were isolated and their adiponectin release in the medium was measured over 2 h. Measures of body fat accumulation and distribution were obtained using dual‐energy X‐ray absorptiometry and computed tomography, respectively. Adiponectin release by omental and subcutaneous adipocytes was similar in lean individuals; however, in subsamples of obese or visceral obese women, adiponectin release by omental adipocytes was significantly reduced while that of subcutaneous adipocytes was not affected. Omental adipocyte adiponectin release was significantly and negatively correlated with total body fat mass (r = ?0.47, P < 0.01), visceral adipose tissue area (r = ?0.50, P < 0.01), omental adipocyte diameter (r = ?0.43, P < 0.01), triglyceride levels (r = ?0.32, P ≤ 0.05), cholesterol/high‐density lipoprotein (HDL)‐cholesterol (r = ?0.31, P ≤ 0.05), fasting glucose (r = ?0.39, P ≤ 0.01), fasting insulin (r = ?0.36, P ≤ 0.05), homeostasis model assessment index (r = ?0.39, P ≤ 0.01), and positively associated with HDL‐cholesterol concentrations (r = 0.33, P ≤ 0.05). Adiponectin release from subcutaneous cells was not associated with any measure of adiposity, lipid profile, or glucose homeostasis. In conclusion, compared to subcutaneous adipocyte adiponectin release, omental adipocyte adiponectin release is reduced to a greater extent in visceral obese women and better predicts obesity‐associated metabolic abnormalities.     

Loss of Total and Visceral Adipose Tissue Mass Predicts Decreases in Oxidative Stress After Weight‐loss Surgery

It is not known whether there are mechanisms linking adipose tissue mass and increased oxidative stress in obesity. This study investigated associations between decreasing general and abdominal fat depots and oxidative stress during weight loss. Subjects were severely obese women who were measured serially at baseline and at 1, 6 (n = 30), and 24 months (n = 18) after bariatric surgery. Total fat mass (FAT) and volumes of visceral (VAT) and subcutaneous abdominal adipose tissue (SAT) were related to plasma concentrations of derivatives of reactive oxidative metabolites (dROMS), a measure of lipid peroxides and oxidative stress. After intervention, BMI significantly decreased, from 47.7 ± 0.8 kg/m² to 43.3 ± 0.8 kg/m² (1 month), 35.2 ± 0.8 kg/m² (6 months), and 30.2 ± 1.2 kg/m² (24 months). Plasma dROMS also significantly deceased over time. At baseline, VAT (r = 0.46), FAT (r = 0.42), and BMI (r = 0.37) correlated with 6‐month decreases in dROMS. Similarly, at 1 month, VAT (r = 0.43) and FAT (r = 0.41) correlated with 6‐month decreases in dROMS. Multiple regression analysis showed that relationships between VAT and dROMS were significant after adjusting for FAT mass. Increased plasma dROMS at baseline were correlated with decreased concentrations of high‐density lipoprotein (HDL) at 1 and 6 months after surgery (r = ?0.38 and ?0.42). This study found longitudinal associations between general, and more specifically intra‐abdominal adiposity, and systemic lipid peroxides, suggesting that adipose tissue mass contributes to oxidative stress.     

Gender differences in tumor necrosis factor alpha and leptin secretion from subcutaneous and visceral fat tissue

Tumor necrosis factor alpha (TNFalpha) and leptin concentrations were determined in the abdominal subcutaneous and visceral (omental) adipose tissue of patients undergoing elective open-abdominal surgery and compared with their body mass index. The concentration of leptin did not differ significantly between women and men, being high in subcutaneous fat tissue and low in visceral fat tissue. TNFalpha concentration in subcutaneous fat tissue was approximately the same in both genders, but it was significantly lower in visceral fat tissue of women and unchanged in visceral fat tissue of men. A significant correlation between BMI and leptin was found in the two fat tissue compartments of both genders, but the correlation between BMI and TNFalpha was found only in subcutaneous fat tissue of women.     

High‐normal tsh values in obesity: Is it insulin resistance or adipose tissue's guilt?

Objective:

Clinical evidences reported subclinical alterations of thyroid function in obesity, although the relationship between thyroid status and obesity remains unclear. We cross‐sectionally investigated the influence of metabolic features on hypothalamic–pituitary–thyroid axis in obesity.

Design and Methods:

We enrolled 60 euthyroid subjects with no history of type 2 diabetes mellitus and assessed the relationship of thyroid function with insulin resistance, measured using euglycemic clamp, and abdominal fat volume, quantified by computed tomography scan (CT scan). Thyroid stimulating hormone (TSH) correlated with BMI (r = 0.46; P = 0.02), both visceral (r = 0.58; P = 0.02) and subcutaneous adipose tissue volumes (r = 0.43; P = 0.03) and insulin resistance (inverse relationship with insulin sensitivity–glucose uptake: r = ?0.40; P = 0.04).

Results:

After performing multivariate regression, visceral adipose tissue volume was found to be the most powerful predictor of TSH (β = 3.05; P = 0.01), whereas glucose uptake, high‐density lipoprotein (HDL) cholesterol, low‐density lipoprotein (LDL) cholesterol, subcutaneous adipose tissue volume, and triglycerides were not. To further confirm the hypothesis that high‐normal TSH values could be dependent on adipose tissue, and not on insulin resistance, we restricted our analyses to moderately obese subjects' BMI ranging 30‐35 kg/m². This subgroup was then divided as insulin resistant and insulin sensitive according to the glucose uptake (≤ or >5 mg·kg^?1·min^?1, respectively). We did not find any statistical difference in TSH (insulin resistant: 1.62 ± 0.65 µU/ml vs. insulin sensitive: 1.46 ± 0.48; P = not significant) and BMI (insulin resistant: 32.2 ± 1.6 kg/m² vs. insulin sensitive: 32.4 ± 1.4; P = not significant), thus confirming absence of correlation between thyroid function and insulin sensitivity per se.

Conclusion:

Our study suggests that the increase in visceral adipose tissue is the best predictor of TSH concentration in obesity, independently from the eventual concurrent presence of insulin resistance.