Measures of adiposity and cardiovascular disease risk factors

Objective: To determine which of five measures of adiposity maintains the strongest association with cardiovascular disease risk factors. Research Methods and Procedures: A nationally representative sample of 12,608 adult participants of the third National Health and Nutrition Examination Survey were examined. Waist circumference, total body fat, percent body fat, BMI, and skinfold thickness were measured following a standardized protocol. Results: In multivariable adjusted models including waist circumference and BMI as independent variables, waist circumference was a significantly better predictor. The odds ratios (95% confidence intervals) for each standard deviation higher waist circumference and BMI for men were as follows: 1.88 (1.43, 2.48) and 0.99 (0.76, 1.29), respectively, for hypertension; 1.51 (0.87, 2.59) and 1.23 (0.76, 1.99), respectively, for diabetes; and 1.85 (1.48, 2.32) and 1.00 (0.80, 1.24), respectively, for low high‐density lipoprotein‐cholesterol. The analogous odds ratios (95% confidence intervals) for women were as follows: 2.28 (1.74, 3.00) and 0.91 (0.69, 1.19), respectively, for hypertension; 2.72 (1.85, 4.00) and 0.82 (0.55, 1.23), respectively, for diabetes; and 1.90 (1.47, 2.47) and 1.07 (0.83, 1.38), respectively, for low high‐density lipoprotein‐cholesterol. Results were markedly similar for waist circumference in models adjusting for total body fat, percent body fat, and skinfold thickness separately. In contrast, waist circumference was not a significantly better predictor of elevated C‐reactive protein than the other measures of adiposity. Discussion: Waist circumference maintains a stronger association with cardiovascular disease risk factors than other measures of adiposity.     

Fitness Alters the Associations of BMI and Waist Circumference with Total and Abdominal Fat

Objective: We tested the following hypotheses in black and white men and women: 1) for a given BMI or waist circumference (WC), individuals with moderate cardiorespiratory fitness (CRF) have lower amounts of total fat mass and abdominal subcutaneous and visceral fat compared with individuals with low CRF; and 2) exercise training is associated with significant reductions in total adiposity and abdominal fat independent of changes in BMI or WC. Research Methods and Procedures: The sample included 366 sedentary male (111 blacks and 255 whites) and 462 sedentary female (203 blacks and 259 whites) participants in the HERITAGE Family Study. The relationships between BMI and WC with total fat mass (determined by underwater weighing) and abdominal subcutaneous and visceral fat (determined by computed tomography) were compared in subjects with low (lower 50%) and moderate (upper 50%) CRF. The effects of a 20‐week aerobic exercise training program on changes in these adiposity variables were examined in 86% of the subjects. Results: Individuals with moderate CRF had lower levels of total fat mass and abdominal subcutaneous and visceral fat than individuals with low CRF for a given BMI or WC value. The 20‐week aerobic exercise program was associated with significant reductions in total adiposity and abdominal fat, even after controlling for reductions in BMI and WC. With few exceptions, these observations were true for both men and women and blacks and whites. Discussion: These findings suggest that a reduction in total adiposity and abdominal fat may be a means by which CRF attenuates the health risk attributable to obesity as determined by BMI and WC.     

Skeletal muscle adiposity is associated with serum lipid and lipoprotein levels in Afro‐Caribbean men

Objective: When compared with other ethnic groups, African ancestry individuals have lower triglycerides and higher High‐density lipoprotein cholesterol (HDL‐C) levels, although the mechanisms for these differences remain unclear. A comprehensive array of factors potentially related to fasting serum lipid and lipoprotein levels in African ancestry men was evaluated. Design and Methods: Men (1,821) underwent dual‐energy X‐ray absorptiometry measures of total body fat and quantitative computed tomography assessments of calf skeletal muscle adiposity [subcutaneous and intermuscular adipose tissue (AT), and muscle density as a measure of intra‐muscular AT]. Results: Multivariable linear regression analysis identified age (?), total body fat (+), subcutaneous AT (?), fasting glucose (+), fasting insulin (+), diastolic blood pressure (+), and non‐African ancestry (+) as independent correlates of triglycerides (all P < 0.05). Total body fat (+), intra‐muscular AT (?), and diastolic blood pressure (+) were independent correlates of Low‐density lipoprotein cholesterol (LDL‐C) (all P < 0.001). Age (+), waist circumference (?), fasting insulin (?), physical activity (+), and alcohol intake (+) were independent correlates of HDL‐C (all P < 0.05). Conclusions: A novel relationship between skeletal muscle adiposity and serum lipid and lipoprotein levels in African ancestry men, independent of total and central adiposity was illuminated. In African ancestry populations, genetic factors are likely a significant determinant of triglycerides levels.     

Methods of Estimation of Visceral Fat: Advantages of Ultrasonography

Objective: To compare methods for the assessment of visceral fat with computed tomography (CT) and establish cutoffs to define visceral obesity based on such alternative methods. Research Methods and Procedures: One hundred women (50.4 ± 7.7 years; BMI 39.2 ± 5.4 kg/m²) underwent anthropometric evaluation, bioelectrical impedance, DXA, abdominal ultrasonography (US), and CT scan. Results: Waist circumference, waist‐to‐hip ratio (WHR), and US‐determined visceral fat values showed the best correlation coefficients with visceral fat determined by CT (r = 0.55, 0.54, and 0.71, respectively; p < 0.01). Fat mass determined by DXA was inversely correlated with visceral‐to‐subcutaneous‐fat ratio (r = ?0.47, p < 0.01). Bioimpedance‐determined fat mass and skinfolds were correlated with only subcutaneous abdominal fat quantified by CT. Linear regression indicated US visceral‐fat distance and WHR as the main predictors of CT‐determined visceral fat (adjusted r² = 0.51, p < 0.01). A waist measurement of 107 cm (82.7% specificity, 60.6% sensitivity) and WHR of 0.97 (78.8% specificity, 63.8% sensitivity) were chosen as discriminator values corresponding with visceral obesity diagnosed by CT. A value of 6.90 cm for visceral fat US‐determined diagnosed visceral obesity with a specificity of 82.8%, a sensitivity of 69.2%, and a diagnostic concordance of 74% with CT. Discussion: US seemed to be the best alternative method for the assessment of intra‐abdominal fat in obese women. Its diagnostic value could be optimized by an anthropometric measurement. Prospective studies are needed to establish CT and US cutoffs for defining visceral‐fat levels related to elevated cardiovascular risk.     

Visceral adiposity and subclinical coronary artery disease in elderly adults: Rancho Bernardo Study

Objective: Despite growing attention to central obesity as a predictor of clinical coronary heart disease (CHD), there are few reports about the association between directly measured visceral obesity and subclinical coronary atherosclerosis in elderly adults. We examined this association in elderly, community‐dwelling adults without clinically recognized CHD. Methods and Procedures: Elderly adults (190 men, BMI 27.2 ± 3.6 kg/m²; 220 women, BMI 25.8 ± 4.6) aged 55–88 years (median 69 years) with no history of CHD or coronary revascularization had an electron beam computed tomography (EBCT) to measure coronary artery calcification score (CACS), an estimate of coronary plaque burden. Visceral and subcutaneous adiposity were assessed by a triple‐slice EBCT scan at the lumbar 4–5 disc level and height, weight, and waist and hip circumferences were measured. Results: In sex‐specific ordinal logistic regression analyses, no measure of obesity or body fat distribution, including BMI, waist‐to‐hip ratio, waist girth, and visceral and subcutaneous fat by EBCT, was significantly associated with CACS before or after adjusting for multiple covariates of CACS (age, smoking, alcohol intake, exercise, pulse pressure, low‐density lipoprotein (LDL)/high‐density lipoprotein (HDL)‐cholesterol ratio, and fasting plasma glucose). Discussion: In elderly adults without clinically recognized CHD, body weight and fat distribution do not predict coronary artery plaque burden. These results raise questions about the value of weight reduction diets for preventing heart disease in elderly survivors without clinical heart disease.     

Prenatal Exposure to Maternal Cigarette Smoking and Accumulation of Intra‐abdominal Fat During Adolescence

In industrialized countries, prenatal exposure to maternal cigarette smoking (PEMCS) is the most common environmental insult to the fetus. Here, we tested the hypothesis that PEMCS amplifies accumulation of abdominal fat during the accelerated weight gain occurring in late puberty. This hypothesis was tested in 508 adolescents (12–18 years, 237 exposed prenatally to maternal cigarette smoking) in whom subcutaneous and intra‐abdominal fat were quantified with magnetic resonance imaging (MRI). We found that, in early puberty, exposed and nonexposed adolescents did not differ in MRI‐based measures of adiposity. In late puberty, on the other hand, exposed compared with nonexposed adolescents demonstrated markedly higher quantities of both subcutaneous fat (by 26%, P = 0.004) and intra‐abdominal fat (by 33%, P = 0.001). These group differences remained virtually unchanged after adjusting for sex and potential confounders, including birth weight and breastfeeding. As such, our results suggest that PEMCS may represent a major risk factor for the development of abdominal obesity at the later stages of puberty.     

Effect of dietary composition of weight loss diets on high‐sensitivity c‐reactive protein: The Randomized POUNDS LOST trial

Objective:

Overweight and obesity are associated with increased high‐sensitivity C‐reactive protein (hsCRP) levels. The purpose of this study was to determine if weight loss diets differing in fat, protein, or carbohydrate composition differentially reduce hsCRP.

Design and Methods:

POUNDS (preventing overweight using novel dietary strategies) LOST was a 2‐year trial of overweight and obese adults randomly allocated to one of four weight loss diets with targeted percentages of energy derived from fat, protein, and carbohydrates (20, 15, 65%; 20, 25, 55%; 40, 15, 45%; 40, 25, 35%, respectively). hsCRP was measured at baseline, 6, and 24 months among 710 participants, and adiposity as measured by dual X‐ray absorptiometry (N = 340) or abdominal computed tomography (N = 126) was correlated with hsCRP change.

Results:

At 6 months, hsCRP was reduced in all trial participants by ?24.7% (Interquartile range (IQR) +7%, ?50%), weight by ?6.7% (IQR ?3%, ?11%), and waist circumference by ?6.0% (IQR ?3%, ?10%) (all P < 0.002), with no significant differences according to dietary composition. The percent change in hsCRP at 6 and 24 months correlated modestly with change in weight, waist circumference, fasting insulin, fasting glucose, HOMA, and most lipid levels. Reductions in hsCRP persisted despite ～ 50% regain of weight by 24 months. The percent change in hsCRP at 24 months significantly correlated with changes in total body fat (r = 0.42), total abdominal adiposity (r = 0.52), subcutaneous abdominal adiposity (r = 0.52), visceral adiposity (r = 0.47), and hepatic tissue density (r = ?0.34) (all P < 0.0006).

Conclusion:

Weight loss decreased hsCRP by similar magnitude, irrespective of dietary composition. Clinicians concerned about inflammation and cardiovascular risk should recommend weight loss diets most likely to succeed for their patients.

     

A comparison of adiposity measures as predictors of all-cause mortality: the Melbourne Collaborative Cohort Study

Objective: Our goal was to examine five different measures of adiposity as predictors of all‐cause mortality. Research Methods and Procedures: Subjects were 16,969 men and 24,344 women enrolled between 1990 and 1994 in the Melbourne Collaborative Cohort Study (27 to 75 years of age). There were 2822 deaths over a median follow‐up period of 11 years. BMI, waist circumference, and waist‐to‐hip ratio were obtained from direct anthropometric measurements. Fat mass and percentage fat were estimated by bioelectric impedance analysis. Results: Comparing the top quintile with the second quintile, for men there was an increased risk of between 20% and 30% for all‐cause mortality associated with each of the anthropometric measures. For women, there was an increased risk of 30% (95% confidence interval for hazard ratio, 1.1–1.6) observed for waist circumference and 50% (1.2–1.8) for waist‐to‐hip ratio, but little or no increased risk for BMI, fat mass, and percentage fat. Waist‐to‐hip ratio was positively and monotonically associated with all‐cause mortality for both men and women. There was a linear association between waist circumference and all‐cause mortality for men, whereas a U‐shaped association was observed for women. Discussion: Measures of central adiposity were better predictors of mortality in women in the Melbourne Collaborative Cohort Study compared with measures of overall adiposity. We recommend measuring waist and hip circumferences in population studies investigating the risk of all‐cause mortality associated with obesity. The use of additional measures such as bioelectric impedance is not justified for this outcome.     

Relationships between direct and indirect measures of central and total adiposity in children: What are we measuring?

Objective: The relationship between central and total fat measured by anthropometry, dual energy X‐ray absorptiometry, and magnetic resonance imaging (MRI) with each other and systolic blood pressure (SBP) was examined. Design and Methods: Participants of the Avon Longitudinal Study of Parents and Children were examined at ages 9, 11, 13, and 15 years (n = 3,796‐6,567). MRI was available on a subset of children at 11 (n = 156) and 13 (n = 95). Results: Body mass index (BMI) and waist circumference (WC) were highly correlated (r = 0.84‐0.91, across ages), and total body fat mass (TBFM) and trunk fat mass (TFM) were very strongly correlated (r ≥ 0.98). Among boys, BMI vs. WC explained a similar degree of variation in TBFM and TFM (41‐71% vs. 43‐76%, across age and overweight groups); in girls, BMI accounted for 62‐73% variance and WC 47‐69%. Adiposity measures were generally similarly correlated with SBP within age groups. Further, the relationship between intra‐abdominal adipose tissue (IAAT) volume and adiposity measures did not vary greatly at 11 (0.65‐0.67) and 13 (0.64‐0.67). Conclusions: BMI and WC contain a large amount of overlapping information as evidenced by their high correlation and similarly sized associations with fat mass, SBP, and IAAT. This suggests that WC may be an inadequate marker of central adiposity during childhood.     

Abdominal obesity and coronary heart disease in Thai men

Objective: To determine the association of four simple anthropometric indices with coronary heart disease (CHD) in Thai men, and to determine the optimal cut‐off points for each index in the prediction of CHD. Research Methods and Procedures: This is a cohort study with 17 years of follow‐up. A total of 2536 male employees from the Electricity Generating Authority of Thailand 35 to 59 years of age at baseline were included in the study. Height, weight, waist circumference, and hip circumference were measured to generate BMI, waist circumference (WC), waist‐to‐hip ratio (WHR), and waist‐to‐height ratio (WHtR). Cox regression models were used to estimate hazard ratios by thirds of each index. Receiver operating characteristic curves were used to assess discrimination of CHD. Results: WHtR was most strongly associated with CHD events in Thai men. The age‐adjusted hazard ratio for those in the highest, compared with the lowest, third was 2.89 (1.37, 6.11). Although WHtR had the largest area under the receiver operating characteristic curve (AUC) with the optimal cut‐off estimated to be 0.51 (sensitivity, 55%; specificity, 61%), no statistically significant difference (p > 0.10) was found between the AUC for WHtR and that for the other three indices. Conclusion: WHtR is, marginally, the best of the four indices considered to predict CHD events in Thai men.     

Regional Intra‐Subject Variability in Abdominal Adiposity Limits Usefulness of Computed Tomography

Objective: Computed tomography (CT) and magnetic resonance imaging, the most accurate methods of abdominal fat measurement, have been applied using a number of protocols, ranging from single‐slice area determination to multiple‐slice volume calculation. The aim of this study was to assess the validity of single‐slice CT for abdominal fat area measurement by estimating the intra‐subject variability in abdominal fat areas and comparing the ranking of subjects across four contiguous abdominal levels. Research Methods and Procedures: Nineteen premenopausal women (age, 35.3 ± 1.4 years; mean ± SE) were studied. CT was used to measure intra‐abdominal fat (IAF) area, percentage of total intra‐abdominal area (%IAF), subcutaneous abdominal fat (SAF) area, and IAF/SAF at four adjacent cross‐sectional lumbar levels (L2–L4). Intra‐subject variability (percentage) was defined as SD/mean × 100. Total body fat was measured by DXA, which was further analyzed for central abdominal fat. Results: Mean body mass index was 24.9 ± 1.0 kg/m². The average (range) intra‐subject variability was 28% (8% to 61%) for IAF, 46% (19% to 124%) for %IAF, 26% (14% to 38%) for SAF area, and 19% (7% to 71%) for IAF/SAF. The pattern of this variability was not uniform between subjects, because their ranking by IAF area was markedly different at each CT level. Discussion: We demonstrated significant intra‐subject variability in CT‐measured adipose tissue areas across four predetermined sites. This resulted in a difference in the ordering of subjects by IAF at each of the four imaging sites, suggesting that the usefulness of single‐slice CT in the assessment of abdominal adiposity in premenopausal women may be limited, particularly when performed for the purpose of making comparisons between subjects based on abdominal fat area.     

Body Fat Patterning,Hepatic Fat and Pancreatic Volume of Non-Obese Asian Indians with Type 2 Diabetes in North India: A Case-Control Study

ObjectiveTo evaluate body fat patterning and phenotype including hepatic fat and pancreatic volume of non-obese (BMI: < 25 kg/m²) Asian Indians with type 2 diabetes residing in North India.MethodsNon-obese patients with type 2 diabetes (n = 93) and non-obese, normo-glycemic subjects (n = 40) were recruited. BMI, waist & hip circumferences, skinfold thickness at 8 sites, body fat, lean mass and detailed abdominal fat evaluation [total abdominal fat, total subcutaneous fat (superficial, deep, anterior, and posterior), total intra-abdominal fat (intra-peritoneal, retroperitoneal)], liver span, grades of fatty liver and pancreatic volume were compared.ResultsWaist circumference, subscapular skinfolds and total truncal fat (on DEXA) were higher whereas calf, total peripheral skinfolds and total leg fat (on DEXA) lower in patients. Specifically, the following volumes were higher in cases as compared to controls; total abdominal fat (19.4%), total intra-abdominal fat (49.7%), intra-peritoneal fat (47.7%), retroperitoneal fat (70.7%), pancreatic volume (26.6%), pancreatic volume index (21.3%) and liver span (10.8%). In cases, significant positive correlations were observed for pancreatic volume with BMI, waist and hip circumferences, W-HR, subscapular, abdominal and total truncal skinfolds, truncal, total subcutaneous, total intra-abdominal, intra-peritoneal, retroperitoneal fat depots, liver span and fatty liver.ConclusionsIn non-obese Asian Indians with type 2 diabetes, subcutaneous and intra-abdominal obesity, including fatty liver, and pancreatic volume were higher and peripheral subcutaneous adiposity was lower than BMI matched non-diabetic subjects. Importantly, increased pancreatic volume in patients was highly correlated with multiple measures of abdominal obesity and liver fat.     

Omental 11beta-hydroxysteroid dehydrogenase 1 correlates with fat cell size independently of obesity

Objectives: In ideopathic obesity, there is evidence that enhanced cortisol regeneration within abdominal subcutaneous adipose tissue may contribute to adiposity and metabolic disease. Whether the cortisol regenerating enzyme, 11β‐hydroxysteroid dehydrogenase type 1 (11βHSD1), or glucocorticoid receptor (GRα) levels are altered in other adipose depots remains uncertain. Our objective was to determine the association between 11βHSD1 and GRα mRNA levels in four distinct adipose depots and measures of obesity and the metabolic syndrome. Research Methods and Procedures: Adipose tissue biopsies were collected from subcutaneous (abdominal, thigh, gluteal) and intra‐abdominal (omental) adipose depots from 21 women. 11βHSD1 and GRα mRNA levels were measured by real‐time polymerase chain reaction. Body composition, fat distribution, fat cell size, and blood lipid, glucose, and insulin levels were measured. Results: 11βHSD1 mRNA was highest in abdominal subcutaneous (p < 0.001) and omental (p < 0.001) depots and was positively correlated with BMI and visceral adiposity in all depots. Omental 11βHSD1 correlated with percent body fat (R = 0.462, p < 0.05), fat cell size (R = 0.72, p < 0.001), and plasma triglycerides (R = 0.46, p < 0.05). Conversely, GRα mRNA was highest in omental fat (p < 0.001). GRα mRNA was negatively correlated with BMI in the abdominal subcutaneous (R = ?0.589, p < 0.05) and omental depots (R = ?0.627, p < 0.05). Omental GRα mRNA was inversely associated with visceral adiposity (R = ?0.507, p < 0.05), fat cell size (R = ?0.52, p < 0.01), and triglycerides (R = ?0.50, p < 0.05). Discussion: Obesity was associated with elevated 11βHSD1 mRNA in all adipose compartments. GRα mRNA is reduced in the omental depot with obesity. The novel correlation of 11βHSD1 with omental fat cell size, independent of obesity, suggests that intracellular cortisol regeneration is a strong predictor of hypertrophy in the omentum.     

Epicardial adipose tissue extent: relationship with age, body fat distribution, and coronaropathy

Epicardial fat is a relatively neglected component of the heart and could be an important risk factor of cardiac disease. The objective of our study was to assess the relationship between epicardial adipose tissue (EAT) extent, fat distribution, and coronaropathy in a group of adult victims of accidental or suspicious sudden death. In 56 cadavers, we performed 34 measurements of EAT from five computerized photographs of the heart (anterior and posterior faces, and three ventricle transversal slices) and analyzed their relationship with anthropometric markers of adiposity (BMI, waist and leg circumference, thickness of abdominal and thigh subcutaneous adipose tissue (SAT)), with the presence and staging of coronary artery disease (CAD), and with markers of myocardial hypertrophy. Simple linear regressions showed that EAT measurements are highly intercorrelated (r from 0.4 to 0.6, P < 0.001), and correlate with age, waist circumference, and heart weight, and to a lesser extent, with BMI, abdominal SAT thickness, and leg SAT thickness. Multiple regression showed that age, waist circumference, and heart weight significantly and independently correlate with EAT (P < 0.0001). No other anthropometric measurement was found independently correlated with EAT. The EAT/myocardium ratios correlated positively with age and waist circumference. Anterior and posterior areas of EAT were found significantly increased in patients with CAD and correlated positively with CAD staging (P = 0.0034, r = 0.38). Anterior EAT surface was found positively associated with CAD (P = 0.01), independently of age and other adiposity measurements. Prospective studies are needed to assess the risk of occurrence/progression of CAD that relate to EAT excess.     

A variant in the LRRFIP1 gene is associated with adiposity and inflammation

Inflammation is an important factor linking abdominal obesity with insulin resistance and related cardiometabolic risk. A genome‐wide association study of adiposity‐related traits performed in the Quebec Family Study (QFS) revealed that a single‐nucleotide polymorphism (SNP) in the LRRFIP1 gene (rs11680012) was associated with abdominal adiposity (P = 4.6 × 10^–6).

Objective:

The objective of this study was to assess the relationship between polymorphisms in LRRFIP1 gene and adiposity (BMI, fat mass (FM), waist circumference (WC), and computed tomography‐derived areas of total, subcutaneous and visceral abdominal adipose tissue) and markers of inflammation (C‐reactive protein (CRP) and interleukin‐6 (IL‐6)).

Design and Methods:

Using Sequenom, 16 tag SNPs in the LRRFIP1 gene, capturing 78% of the genetic variation, were genotyped in 926 participants of the QFS.

Results:

Eight SNPs (rs7575941, rs3769053, rs11689421, rs3820808, rs11680012, rs3806505, rs6739130, and rs11686141) showed evidence of association with at least two adiposity phenotypes and plasma levels of one marker of inflammation. The strongest evidence of association was observed with rs11680012, which explained 1.8–3.4% of the variance in areas of abdominal adiposity and 2.0% of the variation in CRP levels. Carriers of the rare allele of rs11680012 had ～30% more abdominal adiposity (P values between 2.7 × 10^–4 and 3.8 × 10^–6) and 75% higher CRP levels (P = 1.6 × 10^–4) than the common allele in age and sex adjusted data. Rs11680012 is a G/C SNP converting an arginine into a threonine and this amino acid substitution may potentially alter exonic splicing.

Conclusion:

This gene may therefore represent a potential interesting target to investigate in further functional studies on adiposity and inflammation.     

Usefulness of Anthropometry and DXA in Predicting Intra‐abdominal Fat in Obese Men and Women

Objective: To investigate the usefulness of anthropometry and DXA in predicting intra‐abdominal fat (IAF) in obese men and women. Research Methods and Procedures: Observational, cross sectional study of 22 women and 18 men with a body mass index of 30 or above. IAF from 20 cm above and 10 cm below the L4 to L5 intervertebral disc was measured by magnetic resonance imaging (MRI) as a reference method. Central abdominal fat was measured from the upper border of L2 to the lower border of L4 by DXA. Waist and hip circumferences were also measured. Results: In obese women DXA, waist circumference and waist‐hip ratio were equally well correlated with IAF (r = 0.74, 0.75, and 0.70, respectively). In obese men DXA was moderately correlated with IAF measured by MRI (r = 0.46), whereas waist circumference and waist‐hip ratio were not significantly correlated with IAF. Discussion: The prediction of IAF in obese subjects was highly dependent on sex more than in non‐obese persons. Anthropometry and DXA were equally useful in obese women, whereas anthropometry had no predictive power and DXA was the only acceptable predictor of IAF in obese men.     

Relationship of Adipocyte Size with Adiposity and Metabolic Risk Factors in Asian Indians

Background

Enlargement of adipocyte is associated with their dysfunction and alterations in metabolic functions.

Objectives

We evaluated the association of adipocyte size of subcutaneous and omental adipose tissue with body composition and cardiovascular risk factors in Asian Indians.

Methodology

Eighty (40 males and 40 females) non-diabetic adult subjects undergoing elective abdominal surgery were included. Pre-surgery evaluation included anthropometric measurements, % body fat by bioimpedance, abdominal fat area at L_2–3 level (computed tomography) and biochemical investigations (fasting blood glucose and insulin, lipids and hsCRP). During surgery, about 5 grams each of omental and subcutaneous adipose tissue was obtained for adipocyte size determination.

Results

Females had higher BMI, % body fat, skinfold thickness, total and subcutaneous abdominal fat area as compared to males. Overweight was present in 42.5% and 67.5%, and abdominal obesity in 5% and 52.5% males and females, respectively. Subcutaneous adipocyte size was significantly higher than omental adipocyte size. Omental adipocyte size correlated more strongly than subcutaneous adipocyte size with measures of adiposity (BMI, waist circumference, %BF), total and subcutaneous abdominal fat area and biochemical measures (fasting glucose, total cholesterol, triglycerides and HOMA-IR), the correlations being stronger in females. The correlation of adipocyte size with metabolic parameters was attenuated after adjusting for measures of adiposity.

Conclusion

Omental adipocyte size, though smaller than the subcutaneous adipocyte size, was more closely related to measures of adiposity and metabolic parameters. However, the relationship was not independent of measures of adiposity.     

Defining Health‐Related Obesity in Prepubertal Children

Objective: The purpose of this study was to develop percentage of fat and waist circumference cut‐points in prepubertal children with the intention of defining obesity associated with cardiovascular disease (CVD) risk. Research Methods and Procedures: A cross‐sectional analysis of 87 prepubertal children aged 4 to 11 years was used. Percentage of body fat was determined by DXA. Waist circumference was measured to the nearest millimeter. Receiver Operating Characteristic analyses of percentage of fat and waist circumference were used to develop cut‐points for individuals with adverse levels of CVD risk factors. Results: The risk factors selected for analyses (i.e., fasting insulin, high‐density lipoprotein cholesterol, low‐density lipoprotein cholesterol, triglycerides, and total cholesterol/high‐density lipoprotein cholesterol) were significantly related to percentage of body fat and waist circumference. Likelihood ratios were used to identify percentage of fat and waist circumference cut‐points associated with adverse cardiovascular risk profiles. Two cut‐points, an upper cut‐point of 33% body fat and a lower cut‐point of 20% body fat, were derived. Waist circumference cut‐points indicative of adverse and normal risk‐factor profiles were 71 cm and 61 cm, respectively. Discussion: The data indicate that children with ≥33% body fat and children with a waist circumference ≥71 cm were more likely to possess an adverse CVD risk‐factor profile than a normal risk‐factor profile. The likelihood of children with <20% body fat or a waist circumference <61 cm possessing an adverse CVD risk‐factor profile as opposed to a normal risk‐factor profile was small. The cut‐points describe an adequate health‐related definition of childhood obesity.     

Pleiotropic Relationships between Cortisol Levels and Adiposity: The HERITAGE Family Study

Objective: To investigate familial basis for the relationship between cortisol adiposity at baseline and their training responses. Research Methods and Procedures: Bivariate correlation and segregation analyses were employed between cortisol and several adiposity measures [body mass index, fat mass (FM), fat-free mass, percentage of body fat (% BF), abdominal visceral fat (AVF), abdominal subcutaneous fat (ASF), and abdominal total fat (ATF)] from 99 white families and 105 black families. Results: In both races, significant inverse phenotypic correlations were generally observed between cortisol and adiposity measures at baseline but not for training responses. Significant cross-trait familial correlations were found for cortisol with abdominal fat (ASF, AVF, ATF) and overall body adiposity (FM, % BF) measures at baseline, which accounted for 14% to 20% of the phenotypic variance in whites. The cross-trait correlations were not significant for baseline phenotypes in blacks, perhaps because of the small sample size. A bivariate segregation analysis showed evidence of polygenic pleiotropy for cortisol with both abdominal fat and overall adiposity measures that accounted for 14% to 17% of the phenotypic covariance, but major gene pleiotropy was not suggested in whites. However, when ASF, AVF, and ATF were additionally adjusted for FM, no familial cross-trait correlations or polygenic pleiotropy between cortisol and the abdominal fat measures remained. Discussion: Evidence was found for polygenic pleiotropy but not for pleiotropic major gene effects between cortisol and overall adiposity in whites. However, the covariation of cortisol with abdominal fat phenotypes is dependent on concomitant polygenic factors for total-body fat.     

Predictive equations for body fat and abdominal fat with DXA and MRI as reference in Asian Indians

Objective: To develop accurate and reliable equations from simple anthropometric parameters that would predict percentage of total body fat (%BF), total abdominal fat (TAF), subcutaneous abdominal adipose tissue (SCAT), and intra‐abdominal adipose tissue (IAAT) with a fair degree of accuracy. Methods and Procedures: Anthropometry, %BF by dual‐energy X‐ray absorptiometry (DXA) in 171 healthy subjects (95 men and 76 women) and TAF, IAAT, and SCAT by single slice magnetic resonance imaging (MRI) at L3–4 intervertebral level in 100 healthy subjects were measured. Mean age and BMI were 32.2 years and 22.9 kg/m², respectively. Multiple regression analysis was used on the training data set (70%) to develop equations, by taking anthropometric and demographic variables as potential predictors. Predicted equations were applied on validation data set (30%). Results: Multiple regression analysis revealed the best equation for predicting %BF to be: %BF = 42.42 + 0.003 × age (years) + 7.04 × gender (M = 1, F = 2) + 0.42 × triceps skinfold (mm) + 0.29 × waist circumference (cm) ? 0.22 × weight (kg) ? 0.42 × height (cm) (R ² = 86.4%). The most precise predictive equation for estimating IAAT was: IAAT (mm²) = ?238.7 + 16.9 × age (years) + 934.18 × gender (M = 1, F = 2) + 578.09 × BMI (kg/m²) ? 441.06 × hip circumference (cm) + 434.2 × waist circumference (cm) (R ² = 52.1%). SCAT was best predicted by: SCAT (mm²) = ?49,376.4 ? 17.15 × age (years) + 1,016.5 × gender (M = 1, F = 2) +783.3 × BMI (kg/m²) + 466 × hip circumference (cm) (R ² = 67.1). Discussion: We present predictive equations to quantify body fat and abdominal adipose tissue sub‐compartments in healthy Asian Indians. These equations could be used for clinical and research purposes.