Abdominal Visceral Fat is Associated with a BclI Restriction Fragment Length Polymorphism at the Glucocorticoid Receptor Gene Locus

Several investigations have suggested that body fat distribution is influenced by nonpathologic variations in the responsiveness to Cortisol. Genetic variations in the glucocorticoid receptor (GRL) could therefore potentially have an impact on the level of abdominal fat. A restriction fragment length polymorphism (RFLP) has previously been detected with the BelI restriction enzyme in the GRL gene identifying two alleles with fragment lengths of 4.5 and 2.3 kb. This study investigates whether abdominal fat areas measured by computerized tomography (CT) are associated with this polymorphism in 152 middle-aged men and women. The less frequent 4.5-kb allele was found to be associated with a higher abdominal visceral fat (A VF) area independently of total body fat mass (4.5/4.5 vs. 2.3/2.3 kb genotype; men: 190.7 ± 30.1 vs. 150.7 ± 33.3 cm², p=0.04; women: 132.7 ± 37.3 vs. 101.3 ± 34.5 cm², p=0.06). However, the association with AVF was seen only in subjects of the lower tertile of the percent body fat level. In these subjects, the polymorphism was found to account for 41% (p=0.003) and 35% (p=0.007), in men and women, respectively, of the total variance in AVF area. The consistent association between the GRL polymorphism detected with BelI and AVF area suggests that this gene or a locus in linkage disequilibrium with the BelI restriction site may contribute to the accumulation of AVF.     

Visceral and subcutaneous adiposity measurements in adults: influence of measurement site

Objective: Excess abdominal adiposity is a known risk factor for cardiovascular diseases. Computed tomography can be used to examine the visceral (VAT) and subcutaneous (SAT) components of abdominal adiposity, but it is unresolved whether single‐slice or multi‐slice protocols are needed. Research Method and Procedures: Nine computed tomography scans were obtained in the lumbar spine region of 24 adults. The nine slices were obtained at three intervertebral positions (L2–L3, L3–L4, and L4–L5) and at 7 mm above and below these locations. Intra‐site and inter‐site differences in SAT, VAT, total adipose tissue, and the VAT/SAT ratio were examined using ANOVA and confidence intervals for pairwise differences between means. Results: Intervertebral SAT values increased from 103.1 ± 50.9 (standard deviation) cm² at L2–L3 to 153.3 ± 68.8 cm² at L4–L5, whereas the corresponding VAT values decreased from 164.3 ± 125.4 to 126.0 ± 82.7 cm². The VAT/SAT ratio was not constant, decreasing from 1.8 ± 1.4 to 0.9 ± 0.7. Repeated‐measures ANOVA indicated significant inter‐ and intra‐site differences (p ≤ 0.02) for SAT, VAT, and the VAT/SAT ratio at L3?L4 and L4?L5 (p < 0.001). Discussion: These differences show the limitation of using a single‐slice assessment of abdominal fat distribution, both for a subject and between subjects. Furthermore, the sizeable differences in the intra‐site scans indicate that precise repositioning is needed for longitudinal studies. In summary, our findings suggest that a multi‐site imaging protocol may provide a more complete assessment of abdominal fat stores and distribution than use of a single site.     

Dual‐energy X‐ray Absorptiometry and Anthropometric Estimates of Visceral Fat in Black and White South African Women

Visceral adipose tissue (VAT) is associated with increased risk for cardiovascular disease, and therefore, accurate methods to estimate VAT have been investigated. Computerized tomography (CT) is the gold standard measure of VAT, but its use is limited. We therefore compared waist measures and two dual‐energy X‐ray absorptiometry (DXA) methods (Ley and Lunar) that quantify abdominal regions of interest (ROIs) to CT‐derived VAT in 166 black and 143 white South African women. Anthropometry, DXA ROI, and VAT (CT at L4–L5) were measured. Black women were younger (P < 0.001), shorter (P < 0.001), and had higher body fat (P < 0.05) than white women. There were no ethnic differences in waist (89.7 ± 18.2 cm vs. 90.1 ± 15.6 cm), waist:height ratio (WHtR, 0.56 ± 0.12 vs. 0.54 ± 0.09), or DXA ROI (Ley: 2.2 ± 1.5 vs. 2.1 ± 1.4; Lunar: 2.3 ± 1.4 vs. 2.3 ± 1.5), but black women had less VAT, after adjusting for age, height, weight, and fat mass (76 ± 34 cm² vs. 98 ± 35 cm²; P < 0.001). Ley ROI and Lunar ROI were correlated in black (r = 0.983) and white (r = 0.988) women. VAT correlated with DXA ROI (Ley: r = 0.729 and r = 0.838, P < 0.01; Lunar: r = 0.739 and r = 0.847, P < 0.01) in black and white women, but with increasing ROI android fatness, black women had less VAT. Similarly, VAT was associated with waist (r = 0.732 and r = 0.836, P < 0.01) and WHtR (r = 0.721 and r = 0.824, P < 0.01) in black and white women. In conclusion, although DXA‐derived ROIs correlate well with VAT as measured by CT, they are no better than waist or WHtR. Neither DXA nor anthropometric measures are able to accurately distinguish between high and low levels of VAT between population groups.     

Adiponectin and leptin in African Americans

Objective: African Americans (AAs) have less visceral and more subcutaneous fat than whites, thus the relationship of adiponectin and leptin to body fat and insulin sensitivity in AA may be different from that in whites. Methods and Procedures: Sixty‐nine non‐diabetic AA (37 men and 32 women), aged 33 ± 1 year participated. The percent fat was determined by dual‐energy X‐ray absorptiometry, abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) volume by computerized tomography (CT), and insulin sensitivity by homeostasis model assessment (HOMA). Results: VAT was greater in men (1,619 ± 177 cm³ vs. 1,022 ± 149 cm³; P = 0.01); women had a higher percentage of body fat (34.1 ± 1.4 vs. 24.0 ± 1.2; P < 0.0001), adiponectin (15.8 ± 1.2 μg/ml vs. 10.4 ± 0.8 μg/ml; P = 0.0004) and leptin (23.2 ± 15.8 ng/ml vs. 9.2 ± 7.2 ng/ml; P < 0.0001). SAT and HOMA did not differ because of the sex. Adiponectin negatively correlated with VAT (r = ?0.41, P < 0.05) in men, and with VAT (r = ?0.55, P < 0.01), and SAT (r = ?0.35, P < 0.05) in women. Adiponectin negatively correlated with HOMA in men (r = ?0.38, P < 0.05) and women (r = ?0.44, P < 0.05). In multiple regression, sex (P = 0.02), HOMA (P = 0.03) and VAT (P = 0.003) were significant predictors of adiponectin (adj R ² = 0.38, P < 0.0001). Leptin positively correlated with VAT, SAT, percent fat and HOMA in men (r = 0.79, r = 0.86, r = 0.89, and r = 0.53; P < 0.001) and women (r = 0.62, r = 0.75, r = 0.83, and r = 0.55; P < 0.01). In multiple regression VAT (P = 0.04), percent body fat (P < 0.0001) and sex (P = 0.01), but not HOMA were significant predictors of serum leptin (adj R ²= 0.82, P < 0.0001). Discussion: The relationship of adiponectin and leptin to body fat content and distribution in AA is dependent on sex. Although VAT and insulin sensitivity are significant determinants of adiponectin, VAT and percent body fat determine leptin.     

The effect of pioglitazone and resistance training on body composition in older men and women undergoing hypocaloric weight loss

Age‐related increases in ectopic fat accumulation are associated with greater risk for metabolic and cardiovascular diseases, and physical disability. Reducing skeletal muscle fat and preserving lean tissue are associated with improved physical function in older adults. PPARγ‐agonist treatment decreases abdominal visceral adipose tissue (VAT) and resistance training preserves lean tissue, but their effect on ectopic fat depots in nondiabetic overweight adults is unclear. We examined the influence of pioglitazone and resistance training on body composition in older (65–79 years) nondiabetic overweight/obese men (n = 48, BMI = 32.3 ± 3.8 kg/m²) and women (n = 40, BMI = 33.3 ± 4.9 kg/m²) during weight loss. All participants underwent a 16‐week hypocaloric weight‐loss program and were randomized to receive pioglitazone (30 mg/day) or no pioglitazone with or without resistance training, following a 2 × 2 factorial design. Regional body composition was measured at baseline and follow‐up using computed tomography (CT). Lean mass was measured using dual X‐ray absorptiometry. Men lost 6.6% and women lost 6.5% of initial body mass. The percent of fat loss varied across individual compartments. Men who were given pioglitazone lost more visceral abdominal fat than men who were not given pioglitazone (?1,160 vs. ?647 cm³, P = 0.007). Women who were given pioglitazone lost less thigh subcutaneous fat (?104 vs. ?298 cm³, P = 0.002). Pioglitazone did not affect any other outcomes. Resistance training diminished thigh muscle loss in men and women (resistance training vs. no resistance training men: ?43 vs. ?88 cm³, P = 0.005; women: ?34 vs. ?59 cm³, P = 0.04). In overweight/obese older men undergoing weight loss, pioglitazone increased visceral fat loss and resistance training reduced skeletal muscle loss. Additional studies are needed to clarify the observed gender differences and evaluate how these changes in body composition influence functional status.     

Comparison of Regional Fat Distribution and Health Risk Factors in Middle‐Aged White and African American Women: The Healthy Transitions Study

Objective: Both ethnicity and menopause appear to influence intra‐abdominal fat distribution. This study evaluated intra‐abdominal fat distribution and obesity‐related health risks in perimenopausal white and African American women. Research Methods and Procedures: Baseline data from a longitudinal study of changes in body composition and energy balance during menopause are reported. Healthy women (55 African Americans and 103 whites) who were on no medication and had at least five menstrual cycles in the previous 6 months were recruited. Body composition was assessed by DXA, and visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were assessed by computed tomography scan. SAT was divided into deep and superficial layers demarcated by the fascia superficialis. Results: African American women were slightly younger (46.7 ± 0.2 vs. 47.7 ± 0.2 years, p = 0.002) and fatter (42.4% ± 1.0% vs. 39.4% ± 0.8% body fat, p = 0.02) than white women. In unadjusted data, African Americans had significantly more total abdominal fat and total, deep, and superficial SAT than whites. After adjustment for percent body fat and age, only total and superficial SAT remained significantly higher in African Americans. VAT although slightly less in African American women, did not differ significantly by race. In multiple regression analysis, VAT was the strongest predictor of serum lipids, glucose, and insulin in women of both races, although superficial SAT was significantly associated with fasting glucose in whites. Conclusions: Middle‐aged African American women have larger SAT depots, adjusted for total body fatness, but do not differ from white women with regard to VAT. The complexity of the relationship between abdominal fat and metabolic risk is increased by ethnic differences in such associations.     

Visceral Fat Accumulation as a Risk Factor for Prostate Cancer

Objective: No clear association between obesity or body fat distribution and prostate cancer has been shown. We investigated the relation between visceral fat accumulation as measured by computed tomography (CT) and the occurrence of prostate cancer. Research Methods and Procedures: We compared body fat distribution assessed by a direct method (CT) in 63 prostate cancer cases with 63 age‐matched healthy community controls. A CT scan at the level of the fourth lumbar vertebra was performed in all participants. Results: Patients presented a significantly higher mean total abdominal fat area (509.2 ± 226.1 vs. 334.3 ± 132.9 cm², p < 0.001), mostly because of a higher mean visceral fat area (VF; 324.7 ± 145.6 vs. 177.4 ± 88.4 cm², p < 0.001) and a significantly higher mean ratio between visceral and subcutaneous fat areas (V/S ratio; 1.8 ± 0.4 vs. 1.2 ± 0.4, p < 0.001). A significantly higher risk of prostate cancer was found for participants with higher VF (odds ratio = 4.6; 95% confidence interval = 2.6 to 8.2 per SD increase) and V/S ratio (odds ratio = 6.0; 95% confidence interval = 2.3 to 11.0 per SD increase). Discussion: These results suggest a role for visceral obesity, quantified by CT, as a risk factor for prostate cancer. The action of the adipocytokines secreted by visceral fat cells, steroid hormone disturbances, and increased levels of insulin or other hormones noted in visceral obesity may explain this association.     

Epicardial Fat from Echocardiography: A New Method for Visceral Adipose Tissue Prediction

Objective: To validate transthoracic echocardiography as an easy and reliable imaging method for visceral adipose tissue (VAT) prediction. VAT is recognized as an important indicator of high cardiovascular and metabolic risk. Several methods are applied to estimate VAT, with different results. Research Methods and Procedures: We selected 60 healthy subjects (29 women, 31 men, 49.5 ± 16.2 years) with a wide range of body mass indexes. Each subject underwent transthoracic echocardiogram and magnetic resonance imaging (MRI) to measure epicardial fat thickness on the right ventricle. Measurements of epicardial adipose tissue thickness were obtained from the same echocardiographic and MRI views and points. MRI was also used to measure VAT cross‐sectional areas at the level of L4 to L5. Anthropometric indexes were also measured. Results: Subjects with predominant visceral fat accumulation showed higher epicardial adipose tissue thickness than subjects with predominant peripheral fat distribution: 9.97 ± 2.88 vs. 4.34 ± 1.98 (p = 0.005) and 7.19 ± 2.74 vs. 3.43 ± 1.64 (p = 0.004) in men and women, respectively. Simple linear regression analysis showed an excellent correlation between epicardial adipose tissue and waist circumference (r = 0.895, p = 0.01) and MRI abdominal VAT (r = 0.864, p = 0.01). Multiple regression analysis showed that epicardial adipose tissue thickness (r² = 0.442, p = 0.02) was the strongest independent variable correlated to MRI VAT. Bland test confirmed the good agreement between the two methods. Discussion: Epicardial adipose tissue showed a strong correlation with anthropometric and imaging measurements of VAT. Hence, transthoracic echocardiography could be an easy and reliable imaging method for VAT prediction.     

Cardiorespiratory fitness influences the blood pressure response to experimental weight gain

Objective: We tested the hypothesis that with similar weight gain the increase in blood pressure (BP) would be smaller in men with higher cardiorespiratory fitness (HCRF) than in men with lower cardiorespiratory fitness (LCRF). Research Methods and Procedures: Thirteen men (age = 23 ± 1, BMI = 24 ± 1) were overfed by ～1000 kcal/d over ～8 weeks to achieve a 5‐kg weight gain. Resting BP and 24‐hour ambulatory BP, body composition, and fat distribution were measured. Results: Cardiorespiratory fitness (CRF) was higher in the HCRF group compared with the LCRF group (49.9 ± 1.2 vs. 38.1 ± 1.4 mL/kg per minute, p < 0.001). At baseline, body weight was similar in the HCRF and LCRF groups, whereas the HCRF group displayed lower levels of total body fat (13.0 ± 1.7 vs. 16.9 ± 1.3 kg, p = 0.049) and abdominal visceral fat (49 ± 6 vs. 80 ± 14 cm², p = 0.032). Resting BP and 24‐hour ambulatory BP were similar in the two groups at baseline. After weight gain, body weight increased ～5 kg (p < 0.05) in both groups; the changes in body composition and regional fat distribution were similar. As hypothesized, the increases in resting systolic (1 ± 2 vs. 7 ± 2 mm Hg; p = 0.008) and diastolic (?1 ± 4 vs. 5 ± 1 mm Hg; p = 0.005) BP were smaller in the HCRF group. CRF was correlated with the increases in resting systolic (r = ?0.64; p = 0.009) and diastolic BP (r = ?0.80; p < 0.001). Furthermore, the relationship between CRF and BP remained significant after adjusting for the changes in the proportion of total abdominal fat gained as visceral fat. Discussion: These findings suggest that higher levels of CRF are associated with a smaller increase in BP with weight gain, independently of changes in abdominal visceral fat.     

The Peroxisome Proliferator‐Activated Receptor α L162V Mutation Is Associated with Reduced Adiposity

Objective: To determine the contribution of the peroxisome proliferator‐activated receptor α (PPARα) L162V mutation to the variation of several indexes of body fatness obtained from healthy adults who participated in the Quebec Family Study. Research Methods and Procedures: The PPARα L162V mutation was determined by a mismatch polymerase chain reaction method. Adiposity phenotypes were obtained by standardized anthropometric measurements, underwater weighing technique, and computed tomography. Results: For all adiposity phenotypes, subjects carrying the V162 allele had lower values compared with L162 homozygotes (HMZs) [BMI (kg/m²): 27.8 ± 7.6 vs. 26.0 ± 5.6, p < 0.05; percentage body fat: 28.5 ± 10.7 vs. 25.7 ± 10.1, p < 0.05; waist circumference (cm): 89.0 ± 18.1 vs. 85.7 ± 15.8, p = 0.07; total computed tomography abdominal fat areas (cm²): 406 ± 221 vs. 359 ± 192, p = 0.15; means ± SD for L162 HMZs vs. V162 carriers, respectively]. Differences in cross‐sectional abdominal adipose tissue areas and waist circumference were abolished after adjustment for total body fat mass. Similar trends were observed when results were analyzed by gender, although associations seemed stronger in women. The odds ratio of having a BMI above 30 kg/m² reached 1.77 (1.02; 3.07, 95% confidence intervals) for L162 HMZs. This risk could be considered marginal on an individual basis, but because 85% of the subjects are affected by this small risk, the impact on the population is important. Discussion: The PPARα V162 allele is associated with reduced adiposity and has a substantial population‐attributable risk.     

Waist Circumference,BMI, and Visceral Adipose Tissue in White Women and Women of African Descent

Although waist circumference (WC) is a marker of visceral adipose tissue (VAT), WC cut‐points are based on BMI category. We compared WC‐BMI and WC‐VAT relationships in blacks and whites. Combining data from five studies, BMI and WC were measured in 1,409 premenopausal women (148 white South Africans, 607 African‐Americans, 186 black South Africans, 445 West Africans, 23 black Africans living in United States). In three of five studies, participants had VAT measured by computerized tomography (n = 456). Compared to whites, blacks had higher BMI (29.6 ± 7.6 (mean ± s.d.) vs. 27.6 ± 6.6 kg/m², P = 0.001), similar WC (92 ± 16 vs. 90 ± 15 cm, P = 0.27) and lower VAT (64 ± 42 vs. 101 ± 59 cm², P < 0.001). The WC‐BMI relationship did not differ by race (blacks: β (s.e.) WC = 0.42 (.01), whites: β (s.e.) WC = 0.40 (0.01), P = 0.73). The WC‐VAT relationship was different in blacks and whites (blacks: β (s.e.) WC = 1.38 (0.11), whites: β (s.e.) WC = 3.18 (0.21), P < 0.001). Whites had a greater increase in VAT per unit increase in WC. WC‐BMI and WC‐VAT relationships did not differ among black populations. As WC‐BMI relationship did not differ by race, the same BMI‐based WC guidelines may be appropriate for black and white women. However, if WC is defined by VAT, race‐specific WC thresholds are required.     

Effect of Rosiglitazone on Insulin Sensitivity and Body Composition in Type 2 Diabetic Patients

Objective: To investigate the effects of rosiglitazone (RSG) on insulin sensitivity and regional adiposity (including intrahepatic fat) in patients with type 2 diabetes. Research Methods and Procedures: We examined the effect of RSG (8 mg/day, 2 divided doses) compared with placebo on insulin sensitivity and body composition in 33 type 2 diabetic patients. Measurements of insulin sensitivity (euglycemic hyperinsulinemic clamp), body fat (abdominal magnetic resonance imaging and DXA), and liver fat (magnetic resonance spectroscopy) were taken at baseline and repeated after 16 weeks of treatment. Results: There was a significant improvement in glycemic control (glycosylated hemoglobin −0.7 ± 0.7%, p ≤ 0.05) and an 86% increase in insulin sensitivity in the RSG group (glucose-disposal rate change from baseline: 17.5 ± 14.5 μmol glucose/min/kg free fat mass, p < 0.05), but no significant change in the placebo group compared with baseline. Total body weight and fat mass increased (p ≤ 0.05) with RSG (2.1 ± 2.0 kg and 1.4 ± 1.6 kg, respectively) with 95% of the increase in adiposity occurring in nonabdominal regions. In the abdominal region, RSG increased subcutaneous fat area by 8% (25.0 ± 28.7 cm², p = 0.02), did not alter intra-abdominal fat area, and reduced intrahepatic fat levels by 45% (−6.7 ± 9.7%, concentration relative to water). Discussion: Our data indicate that RSG greatly improves insulin sensitivity in patients with type 2 diabetes and is associated with an increase in adiposity in subcutaneous but not visceral body regions.     

Dysregulation of the Autonomic Nervous System Can Be a Link between Visceral Adiposity and Insulin Resistance

Objective: To evaluate the interplay among abdominal adipose tissue distribution, the cortisol axis, the autonomic nervous system, and insulin resistance. Research Methods and Procedures: Two age‐, sex‐, and BMI‐matched groups were studied. Fifteen subjects were first‐degree relatives of patients with type 2 diabetes (R), and 15 had no family history of diabetes (controls, C). A hyperinsulinemic euglycemic clamp, cortisol measurements, and analysis of heart rate variability (HRV) were performed. Computed tomography was performed in a subgroup (n = 9 + 9) to determine abdominal adipose tissue distribution. Results: R tended to be less insulin‐sensitive than C (M value 9.2 ± 1.0 vs 10.3 ± 0.7 mg/kg per minute, not significant). Stimulation with tetracosactin or corticotropin releasing hormone yielded lower peak serum cortisol levels in R (p = 0.03 and p = 0.06, respectively). The amount of visceral abdominal fat (VAT) tended to be greater in R. In all subjects, VAT was negatively correlated to insulin sensitivity (r = ?0.93, p < 0.001). There was a positive association between VAT and resting heart rate (r = 0.70, p = 0.003) and sympathetic/parasympathetic ratio in HRV assessment after tilt (r = 0.53, p = 0.03). Subcutaneous abdominal tissue was not associated with insulin sensitivity or any of the hormonal or HRV assessments. Discussion: Subjects genetically predisposed for type 2 diabetes had a tendency toward a larger amount of VAT and to lower insulin sensitivity compared with control subjects. The amount of visceral fat was strongly associated with insulin resistance and signs of a high ratio of sympathetic vs. parasympathetic reactivity. A large amount of visceral fat may act in concert with sympathetic/parasympathetic imbalance to promote the development of insulin resistance, and this may be partly independent of genetic background.     

Body Composition Changes in Caucasian and African American Children and Adolescents with Obesity Using Dual-Energy X-ray Absorptiometry Measurements after a 10-Week Weight Loss Program

Objective : Changes in body composition during a weight loss program have not been described in children. We wanted to test the hypothesis that weight loss can be achieved while maintaining total body fat-free mass. Research Methods and Procedures : We determined body composition changes by using dual-energy X-ray absorptiometry measured at baseline and after the first 10 weeks of a multidisciphnary weight loss program. The program consisted of 10 weekly group sessions where the children were provided instruction in lifestyle modification, including diet and exercise. Program leaders included a pediatrician, psychologist, registered dietitian, and exercise instructor. Results : We studied 59 obese children, mean (± SD) age 12.8 ± 2.6 years, 29% boys and 71% girls, 49% Caucasian, and 51% African American. At enrollment, the children's mean height and body mass index were 157 cm and 38.9 kg/m², respectively. The children's dual-energy X-ray absorptiometry-derived mean at baseline and at 10 weeks and corresponding p values were: weight (94.6 kg vs. 92.3 kg, p<0.0001), total body fat mass (46.9 kg vs. 44.3 kg, p<0.0001), percentage total body fat (49.2% vs. 47.5%, p<0.0001), total trunk mass (43.0 kg vs. 41.5 kg,p<0.0001), total trunk fat (21.2 kg vs. 20.0 kg, p<0.0001), total body fat-free mass (47.6 kg vs. 47.9 kg, p = 0.33), total body bone mass (2.7 kg vs. 2.7 kg, p = 0.99), and total body bone mineral density (1.14 g/cm² vs. 1.15 g/cm², p = 0.0119). The children's race, gender, or Tanner stage did not affect these changes. Discussion : Decreases in total body fat mass was achieved, and total body fat-free mass was maintained among boy and girl Caucasian and African American children participating in this lifestyle modification weight loss program.     

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.     

Differential Effects of Abdominal Adipose Tissue Distribution on Insulin Sensitivity in Black and White South African Women

Black South African women are more insulin resistant than BMI‐matched white women. The objective of the study was to characterize the determinants of insulin sensitivity in black and white South African women matched for BMI. A total of 57 normal‐weight (BMI 18–25 kg/m²) and obese (BMI > 30 kg/m²) black and white premenopausal South African women underwent the following measurements: body composition (dual‐energy X‐ray absorptiometry), body fat distribution (computerized tomography (CT)), insulin sensitivity (S_I, frequently sampled intravenous glucose tolerance test), dietary intake (food frequency questionnaire), physical activity (Global Physical Activity Questionnaire), and socioeconomic status (SES, demographic questionnaire). Black women were less insulin sensitive (4.4 ± 0.8 vs. 9.5 ± 0.8 and 3.0 ± 0.8 vs. 6.0 ± 0.8 × 10^?5/min/(pmol/l), for normal‐weight and obese women, respectively, P < 0.001), but had less visceral adipose tissue (VAT) (P = 0.051), more abdominal superficial subcutaneous adipose tissue (SAT) (P = 0.003), lower SES (P < 0.001), and higher dietary fat intake (P = 0.001) than white women matched for BMI. S_I correlated with deep and superficial SAT in both black (R = ?0.594, P = 0.002 and R = 0.495, P = 0.012) and white women (R = ?0.554, P = 0.005 and R = ?0.546, P = 0.004), but with VAT in white women only (R = ?0.534, P = 0.005). In conclusion, body fat distribution is differentially associated with insulin sensitivity in black and white women. Therefore, the different abdominal fat depots may have varying metabolic consequences in women of different ethnic origins.     

High visceral fat mass and high liver fat are associated with resistance to lifestyle intervention

Objective: High visceral adipose tissue (VAT) and high liver fat (LF) are associated with the metabolic syndrome and diabetes. We studied changes in these two fat depots during weight loss and analyzed whether VAT and LF at baseline predict the response to lifestyle intervention. Research Methods and Procedures: One hundred twelve subjects (48 men and 64 women; age, 46 ± 11 years; BMI, 29.2 ± 4.4 kg/m²) were studied after a follow up‐time of 264 ± 60 (SD) days. Insulin sensitivity was estimated from the oral glucose tolerance test. Body fat depots were quantified using magnetic resonance imaging and spectroscopy. Results: Cross‐sectionally high VAT (r = ?0.22, p = 0.02) and high LF (r = ?0.36, p < 0.0001) were independently associated with low insulin sensitivity. With intervention, BMI (?3.0%), VAT (?12.0%), and LF (?33.0%) were reduced (all p < 0.001). Insulin sensitivity was improved (+17%, p < 0.01). The changes in BMI (r = ?0.41), VAT (r = ?0.28), and LF (r = ?0.39) were associated with the increase in insulin sensitivity (all p < 0.01). High VAT (r = ?0.28, p = 0.01) and high LF (r = ?0.38, p < 0.01) at baseline were associated with a lesser increase in insulin sensitivity. Discussion: Baseline values and changes in BMI, VAT, and LF are related to changes in insulin sensitivity during lifestyle intervention. Subjects with high VAT and LF have a lower chance of profiting from lifestyle intervention and may require intensified lifestyle prevention strategies or even pharmacological approaches to improve insulin sensitivity.     

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.     

Metabolic Response to a Mixed Meal in Obese and Lean Women from Two South African Populations

Objective: Lower lipid and insulin levels are found during a glucose-tolerance test in obese black than obese white South African women. Therefore, β-cell function and lipid metabolism were compared in these populations during a mixed meal. Research Methods and Procedures: Blood concentrations of glucose, free fatty acids (FFAs), insulin, lipograms, and in vivo FFA oxidation were determined at fasting and for 7 hours after oral administration of a mixed emulsion containing glucose-casein-sucrose-lipid and [1-¹³C] palmitic acid in 8 lean black women (LBW), 10 obese black women (OBW), 9 lean white women (LWW), and 10 obese white women (OWW). Subcutaneous and visceral fat mass was assessed by computerized tomography. Results: Visceral fat area was higher in OWW (152.7 ± 17.0 cm²) than OBW (80.0 ± 6.7 cm²; p < 0.01). In OBW, 30-minute insulin levels were higher (604.3 ± 117.6 pM) than OWW (311.0 ± 42.9 pM; p < 0.05). Total triglyceride was higher in OWW (706.7 ± 96.0 mM × 7 hours) than OBW (465.7 ± 48.2 mM × 7 hours; p < 0.05) and correlated with visceral fat area (β = 0.38, p = 0.05). Palmitate oxidation was higher in lean than obese women in both ethnic groups and correlated negatively with fat mass (β = −0.58, p < 0.005). Discussion: The higher 30-minute insulin response in OBW may reflect a higher insulinotropic effect of FFAs or glucose. The elevated triglyceride level of OWW may be due to their higher visceral fat mass and possibly reduced clearance by adipose tissue.     

Association Between the 4 bp Proinsulin Gene Insertion Polymorphism (IVS‐69) and Body Composition in Black South African Women

The objective of the study was to examine the association between a functional 4 bp proinsulin gene insertion polymorphism (IVS‐69), fasting insulin concentrations, and body composition in black South African women. Body composition, body fat distribution, fasting glucose and insulin concentrations, and IVS‐69 genotype were measured in 115 normal‐weight (BMI <25 kg/m²) and 138 obese (BMI ≥30 kg/m²) premenopausal women. The frequency of the insertion allele was significantly higher in the class 2 obese (BMI ≥35kg/m²) compared with the normal‐weight group (P = 0.029). Obese subjects with the insertion allele had greater fat mass (42.3 ± 0.9 vs. 38.9 ± 0.9 kg, P = 0.034) and fat‐free soft tissue mass (47.4 ± 0.6 vs. 45.1 ± 0.6 kg, P = 0.014), and more abdominal subcutaneous adipose tissue (SAT, 595 ± 17 vs. 531 ± 17 cm², P = 0.025) but not visceral fat (P = 0.739), than obese homozygotes for the wild‐type allele. Only SAT was greater in normal‐weight subjects with the insertion allele (P = 0.048). There were no differences in fasting insulin or glucose levels between subjects with the insertion allele or homozygotes for the wild‐type allele in the normal‐weight or obese groups. In conclusion, the 4 bp proinsulin gene insertion allele is associated with extreme obesity, reflected by greater fat‐free soft tissue mass and fat mass, particularly SAT, in obese black South African women.