Obesity

St‐Onge, Marie‐Pierre

doi: 10.1038/oby.2010.103pmid: 20978478

Data from National Health and Nutrition Examination Surveys (NHANES) 1999–2004 have recently shown the percent body fat of American adults. Average American men and women have ∼28 and 40% body fat. When categorized by BMI and age, the data also show high percent body fat values, particularly in lower BMI categories. These data should make one reflect on the health status of Americans in all BMI categories and the use of these data for public health recommendations.

Ström, Anna; Melnikov, Sergey M.; Boers, Hanny M.; Mela, David J.; Peters, Harry P.F.

doi: 10.1038/oby.2010.61pmid: 20978479

Camilleri, Michael; Odunsi‐Shiyanbade, Suwebatu T.; Vazquez‐Roque, Maria I.

doi: 10.1038/oby.2010.99pmid: N/A

Zhang, Hanrui; Zhang, Cuihua

doi: 10.1038/oby.2010.91pmid: 20395945

Teixeira, Diana; Pestana, Diogo; Faria, Ana; Calhau, Conceição; Azevedo, Isabel; Monteiro, Rosário

doi: 10.1038/oby.2010.100pmid: 20467421

It is recognized that the endocannabinoid system (ECS) plays a crucial role in the modulation of food intake and other aspects of energy metabolism. In this study, we aimed to investigate the effects of Δ9‐tetrahydrocannabinol (THC) on adipocyte biology. 3T3–L1 cells were used to evaluate proliferation by sulforhodamine B (SRB) staining and methyl−3H‐thymidine incorporation after 48 or 72 h of treatment with THC (1–500 nmol/l). Cells were differentiated in the presence or absence of the cannabinoid, and adipogenesis was determined by measuring lipid accumulation and peroxisome proliferator‐activated receptor γ (PPARγ) transcription through reverse transcriptase‐PCR (RT‐PCR). Lipolysis was quantified under basal conditions or after isoproterenol (IP, 100 nmol/l) or insulin (INS, 100 nmol/l) treatment. Transforming growth factor β (TGFβ), diacylglycerol lipase α, and N‐acylphosphatidylethanolamine‐specific phospholipase D (NAPE‐PLD) transcriptions were determined by RT‐PCR in preadipocytes and adipocytes and adiponectin only in adipocytes. THC treatment increased culture protein content and reduced methyl−3H‐thymidine incorporation. Cells treated with THC underwent adipogenesis shown by the expression of PPARγ and had increased lipid accumulation. Basal and IP‐stimulated lipolyses were inhibited by THC and there was no effect on lipolysis of INS‐treated adipocytes. The effects on methyl−3H‐thymidine incorporation and lipolysis seem to be mediated through CB1‐ and CB2‐dependent pathways. THC decreased NAPE‐PLD in preadipocytes and increased adiponectin and TGFβ transcription in adipocytes. These results show that the ECS interferes with adipocyte biology and may contribute to adipose tissue (AT) remodeling. Although these observations point toward increased AT deposition, the stimulation of adiponectin production and inhibition of lipolysis may be in favor of improved INS sensitivity under cannabinoid influence.

Chandler‐Laney, Paula C.; Phadke, Radhika P.; Granger, Wesley M.; Muñoz, Julian A.; Man, Chaira; Cobelli, Claudio; Ovalle, Fernando; Fernández, Jose R.; Gower, Barbara A.

doi: 10.1038/oby.2010.44pmid: 20300083

The prevalence of type 2 diabetes is higher among African Americans (AA) vs. European Americans (EA), is highest at middle age, and is related to obesity. This study was conducted to test the hypothesis that the association of adiposity (percent body fat (%fat)) with indexes of insulin sensitivity (SI) and β‐cell function would differ with ethnicity and age. Subjects were 168 healthy, normoglycemic AA and EA girls and women aged 7–12 years, 18–32 years, and 40–70 years. An intravenous glucose tolerance test (IVGTT) was used to assess indexes of insulin secretion and action: SI, acute C‐peptide secretion (X0); basal, first‐phase, second‐phase, and total β‐cell responsivity to glucose (PhiB, Phi1, Phi2, and PhiTOT, respectively); and the disposition index (DI = SI × PhiTOT). %Fat was assessed with dual energy X‐ray absorptiometrys. Adiposity was significantly associated with SI among EA (−0.57, P < 0.001) but not AA (−0.20, P = 0.09). Adiposity appeared stimulatory to β‐cell function in the two groups of younger subjects and in EA, but inhibitory in postmenopausal women, particularly AA postmenopausal women. Among AA postmenopausal women, %fat was inversely associated with Phi1 (r = −0.57, P < 0.05) and PhiTOT (r = −0.68, P < 0.01). These results suggest that the impact of adiposity on insulin secretion and action differs with age and ethnicity.

Perreault, Leigh; Bergman, Bryan C.; Hunerdosse, Devon M.; Eckel, Robert H.

doi: 10.1038/oby.2010.76pmid: 20379150

Whether sex differences in intramuscular triglyceride (IMTG) metabolism underlie sex differences in the progression to diabetes are unknown. Therefore, the current study examined IMTG concentration and fractional synthesis rate (FSR) in obese men and women with normal glucose tolerance (NGT) vs. those with prediabetes (PD). PD (n = 13 men and 7 women) and NGT (n = 7 men and 12 women) groups were matched for age and anthropometry. Insulin action was quantified using a hyperinsulinemic‐euglycemic clamp with infusion of (6,6−2H2)‐glucose. IMTG concentration was measured by gas chromatography/mass spectrometry (GC/MS) and FSR by GC/combustion isotope ratio MS (C‐IRMS), from muscle biopsies taken after infusion of (U−13C)palmitate during 4 h of rest. In PD men, the metabolic clearance rate (MCR) of glucose was lower during the clamp (4.71 ± 0.77 vs. 8.62 ± 1.26 ml/kg fat‐free mass (FFM)/min, P = 0.04; with a trend for lower glucose rate of disappearance (Rd), P = 0.07), in addition to higher IMTG concentration (41.2 ± 5.0 vs. 21.2 ± 3.4 µg/mg dry weight, P ≤ 0.01), lower FSR (0.21 ± 0.03 vs. 0.42 ± 0.06 %/h, P ≤ 0.01), and lower oxidative capacity (P = 0.03) compared to NGT men. In contrast, no difference in Rd, IMTG concentration, or FSR was seen in PD vs. NGT women. Surprisingly, glucose Rd during the clamp was not different between NGT men and women (P = 0.25) despite IMTG concentration being higher (42.6 ± 6.1 vs. 21.2 ± 3.4 µg/mg dry weight, P = 0.03) and FSR being lower (0.23 ± 0.04 vs. 0.42 ± 0.06 %/h, P = 0.02) in women. Alterations in IMTG metabolism relate to diminished insulin action in men, but not women, in the progression toward diabetes.

Bush, Nikki C.; Alvarez, Jessica A.; Choquette, Suzanne S.; Hunter, Gary R.; Oster, Robert A.; Darnell, Betty E.; Gower, Barbara A.

doi: 10.1038/oby.2010.39pmid: 20203630

Calcium intake is reported to enhance weight loss with a preferential loss in trunk fat. Discrepant findings exist as to the effects of calcium intake on longitudinal changes in total fat mass and central fat deposition. Therefore, the purpose of this study was to determine associations between dietary calcium intake and 1‐year change in body composition and fat distribution, specifically intra‐abdominal adipose tissue (IAAT). A total of 119 healthy, premenopausal women were evaluated at baseline and 1 year later. Average dietary calcium was determined via 4‐day food records. Total fat was determined by dual‐energy X‐ray absorptiometry (DXA) and subcutaneous abdominal adipose tissue (SAAT) and IAAT by computed tomography. Over the study period, participants' reported daily calcium and energy intakes were 610.0 ± 229.9 mg and 1,623.1 ± 348.5 kcal, respectively. The mean change in weight, total fat, IAAT, and SAAT was 4.9 ± 4.4 kg, 5.3 ± 4.0 kg, 7.7 ± 19.5 cm2, and 49.3 ± 81.1 cm2, respectively. Average calcium intake was significantly, inversely associated with 1‐year change in IAAT (standardized β: −0.23, P < 0.05) after adjusting for confounding variables. For every 100 mg/day of calcium consumed, gain in IAAT was reduced by 2.7 cm2. No significant associations were observed for average calcium intake with change in weight, total fat, or SAAT. In conclusion, dietary calcium intake was significantly associated with less gain in IAAT over 1 year in premenopausal women. Further investigation is needed to verify these findings and determine the calcium intake needed to exert beneficial effects on fat distribution.

Chang, Hye M.; Lee, Hea J.; Park, Hye S.; Kang, Jae H.; Kim, Kyung S.; Song, Young S.; Jang, Yeon J.

doi: 10.1038/oby.2010.60pmid: 20339362

Visceral adipose tissue‐derived serpin (vaspin) has been regarded as a novel adipokine with potential insulin sensitizing properties. We investigated the changes of serum vaspin concentration in response to weight reduction, and the associations between changes in serum vaspin concentrations and changes of anthropometric and metabolic variables in obese subjects after weight reduction. We performed a longitudinal clinical intervention study on 63 obese persons enrolled in a 12‐week weight reduction program that included lifestyle modification and adjuvant treatment with the antiobesity agent orlistat. Anthropometric variables, lipid profiles, fasting glucose, fasting insulin, and serum vaspin concentrations were measured. Statistical analyses were performed according to the homeostasis model assessment of insulin resistance (HOMAIR). Serum vaspin concentrations decreased significantly in responders (≥2% reduction in baseline weight), but not in nonresponders (<2% reduction in baseline weight). Changes in serum vaspin concentrations were significantly correlated with body weight, BMI, waist circumference, and hip circumference in the higher, but not in the lower, HOMAIR group. In multivariate linear regression analysis, change in serum vaspin concentrations in the higher, but not in the lower, HOMAIR group was positively correlated with change in BMI and negatively correlated with initial HOMAIR level. The associations between changes in serum vaspin concentrations and changes in anthropometric and metabolic parameters differed according to insulin resistance status in obese subjects. These relationships were more prominent in the higher HOMAIR group. Insulin resistance may influence the correlations between changes in serum vaspin concentration and related metabolic variables.

Bosy‐Westphal, Anja; Kossel, Elke; Goele, Kristin; Blöcker, Thordis; Lagerpusch, Merit; Later, Wiebke; Heller, Martin; Glüer, Claus C.; Müller, Manfred J.

doi: 10.1038/oby.2010.49pmid: 20224561

Pericardial adipose tissue (PAT) is positively associated with fatty liver and obesity‐related insulin resistance. Because PAT is a well‐known marker of visceral adiposity, we investigated the impact of weight loss on PAT and its relationship with liver fat and insulin sensitivity independently of body fat distribution. Thirty overweight nondiabetic women (BMI 28.2–46.8 kg/m2, 22–41 years) followed a 14.2 ± 4‐weeks low‐calorie diet. PAT, abdominal subcutaneous (SAT), and visceral fat volumes (VAT) were measured by magnetic resonance imaging (MRI), total fat mass, trunk, and leg fat by dual‐energy X‐ray absorptiometry and intrahepatocellular lipids (IHCL) by (1)H‐magnetic resonance spectroscopy. Euglycemic hyperinsulinemic clamp (M) and homeostasis model assessment of insulin resistance (HOMAIR) were used to assess insulin sensitivity or insulin resistance. At baseline, PAT correlated with VAT (r = 0.82; P < 0.001), IHCL (r = 0.46), HOMAIR (r = 0.46), and M value (r = −0.40; all P < 0.05). During intervention, body weight decreased by −8.5%, accompanied by decreases of −12% PAT, −13% VAT, −44% IHCL, −10% HOMA2‐%B, and +24% as well as +15% increases in HOMA2‐%S and M, respectively. Decreases in PAT were only correlated with baseline PAT and the loss in VAT (r = −0.56; P < 0.01; r = 0.42; P < 0.05) but no associations with liver fat or indexes of insulin sensitivity were observed. Improvements in HOMAIR and HOMA2‐%B were only related to the decrease in IHCL (r = 0.62, P < 0.01; r = 0.65, P = 0.002) and decreases in IHCL only correlated with the decrease in VAT (r = 0.61, P = 0.004). In conclusion, cross‐sectionally PAT is correlated with VAT, liver fat, and insulin resistance. Longitudinally, the association between PAT and insulin resistance was lost suggesting no causal relationship between the two.