Relationships between insulin sensitivity and measures of body fat in asymptomatic men and women

DEXA Scan Body Fat Mass Distribution in Obese and Non-Obese Individuals and Risk of NAFLD-Analysis of 10,865 Individuals

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide yet predicting non-obese NAFLD is challenging. Thus, this study investigates the potential of regional fat percentages obtained by dual-energy X-ray absorptiometry (DXA) in accurately assessing NAFLD risk. Using the United States National Health and Nutrition Examination Survey (NHANES) 2011−2018, multivariate logistic regression and marginal analysis were conducted according to quartiles of regional fat percentages, stratified by gender. A total of 23,752 individuals were analysed. Males generally showed a larger increase in marginal probabilities of NAFLD development than females, except in head fat, which had the highest predictive probabilities of non-obese NAFLD in females (13.81%, 95%CI: 10.82−16.79) but the lowest in males (21.89%, 95%CI: 20.12−23.60). Increased percent of trunk fat was the strongest predictor of both non-obese (OR: 46.61, 95%CI: 33.55−64.76, p < 0.001) and obese NAFLD (OR: 2.93, 95%CI: 2.07−4.15, p < 0.001), whereas raised percent gynoid and leg fat were the weakest predictors. Ectopic fat deposits are increased in patients with non-obese NAFLD, with greater increases in truncal fat over gynoid fat. As increased fat deposits in all body regions can increase odds of NAFLD, therapeutic intervention to decrease ectopic fat, particularly truncal fat, may decrease NAFLD risk.

Body Composition and Metabolomics in the Alberta Physical Activity and Breast Cancer Prevention Trial

BACKGROUND

Obesity is correlated with many biomarkers, but the extent to which these correlate with underlying body composition is poorly understood.

OBJECTIVES

Our objectives were to 1) describe/compare distinct contributions of fat/lean mass with BMI-metabolite correlations and 2) identify novel metabolite biomarkers of fat/lean mass.

METHODS

The Alberta Physical Activity and Breast Cancer Prevention Trial was a 2-center randomized trial of healthy, inactive, postmenopausal women (n = 304). BMI (in kg/m2) was calculated using weight and height, whereas DXA estimated fat/lean mass. Ultra-performance liquid chromatography and mass spectrometry measured relative concentrations of serum metabolite concentrations. We estimated partial Pearson correlations between 1052 metabolites and BMI, adjusting for age, smoking, and site. Fat mass index (FMI; kg/m2) and lean mass index (LMI; kg/m2) correlations were estimated similarly, with mutual adjustment to evaluate independent effects.

RESULTS

Using a Bonferroni-corrected α level <4.75 × 10-5,  we observed 53 BMI-correlated metabolites (|r| = 0.24-0.42). Of those, 21 were robustly correlated with FMI (|r| > 0.20), 25 modestly (0.10 ≤ |r| ≤ 0.20), and 7 virtually null (|r| < 0.10). Ten of 53 were more strongly correlated with LMI than with FMI. Examining non-BMI-correlated metabolites, 6 robustly correlated with FMI (|r| = 0.24-0.31) and 2 with LMI (r = 0.25-0.26). For these, correlations for fat and lean mass were in opposing directions compared with BMI-correlated metabolites, in which correlations were mostly in the same direction.

CONCLUSIONS

Our results demonstrate how a thorough evaluation of the components of fat and lean mass, along with BMI, provides a more accurate assessment of the associations between body composition and metabolites than BMI alone. Such an assessment makes evident that some metabolites correlated with BMI predominantly reflect lean mass rather than fat, and some metabolites related to body composition are not correlated with BMI. Correctly characterizing these relations is important for an accurate understanding of how and why obesity is associated with disease.

A multidimensional functional fitness score has a stronger association with type 2 diabetes than obesity parameters in cross sectional data

Objectives

We examine here the association of multidimensional functional fitness with type 2 diabetes mellitus (T2DM) as compared to anthropometric indices of obesity such as body mass index (BMI) and waist to hip ratio (WHR) in a sample of Indian population.

Research design and method

We analysed retrospective data of 663 volunteer participants (285 males and 378 females between age 28 and 84), from an exercise clinic in which every participant was required to undergo a health related physical fitness (HRPF) assessment consisting of 15 different tasks examining 8 different aspects of functional fitness.

Results

The odds of being diabetic in the highest quartile of BMI were not significantly higher than that in the lowest quartile in either of the sexes. The odds of being a diabetic in the highest WHR quartile were significantly greater than the lowest quartile in females (OR = 4.54 (1.95, 10.61) as well as in males (OR = 3.81 (1.75, 8.3). In both sexes the odds of being a diabetic were significantly greater in the lowest quartile of HRPF score than the highest (males OR = 10.52 (4.21, 26.13); females OR = 10.50 (3.53, 31.35)). After removing confounding, the predictive power of HRPF was significantly greater than that of WHR. HRPF was negatively correlated with WHR, however for individuals that had contradicting HRPF and WHR based predictions, HRPF was the stronger predictor of T2DM.

Conclusion

The association of multidimensional functional fitness score with type 2 diabetes was significantly stronger than obesity parameters in a cross sectional self-selected sample from an Indian city.

Causal relationships between obesity and the leading causes of death in women and men

Obesity traits are causally implicated with risk of cardiometabolic diseases. It remains unclear whether there are similar causal effects of obesity traits on other non-communicable diseases. Also, it is largely unexplored whether there are any sex-specific differences in the causal effects of obesity traits on cardiometabolic diseases and other leading causes of death. We constructed sex-specific genetic risk scores (GRS) for three obesity traits; body mass index (BMI), waist-hip ratio (WHR), and WHR adjusted for BMI, including 565, 324, and 337 genetic variants, respectively. These GRSs were then used as instrumental variables to assess associations between the obesity traits and leading causes of mortality in the UK Biobank using Mendelian randomization. We also investigated associations with potential mediators, including smoking, glycemic and blood pressure traits. Sex-differences were subsequently assessed by Cochran's Q-test (Phet). A Mendelian randomization analysis of 228,466 women and 195,041 men showed that obesity causes coronary artery disease, stroke (particularly ischemic), chronic obstructive pulmonary disease, lung cancer, type 2 and 1 diabetes mellitus, non-alcoholic fatty liver disease, chronic liver disease, and acute and chronic renal failure. Higher BMI led to higher risk of type 2 diabetes in women than in men (Phet = 1.4×10-5). Waist-hip-ratio led to a higher risk of chronic obstructive pulmonary disease (Phet = 3.7×10-6) and higher risk of chronic renal failure (Phet = 1.0×10-4) in men than women. Obesity traits have an etiological role in the majority of the leading global causes of death. Sex differences exist in the effects of obesity traits on risk of type 2 diabetes, chronic obstructive pulmonary disease, and renal failure, which may have downstream implications for public health.

Mendelian randomisation in type 2 diabetes and coronary artery disease

Type 2 diabetes, coronary artery disease and hypertension are associated with anthropometric and biomarker traits, including waist-to-hip-ratio, body mass index and altered glucose and insulin levels. Clinical trials, for example of weight-loss interventions, show these factors are causal, but lifelong impact of subtle changes in body mass index and body fat distribution are less clear. The use of human genetics can quantify the causal effects of long-term exposure to subtle changes of modifiable risk factors. Mendelian randomisation (MR) uses human genetic variants associated with the risk factor to quantify the relationship between risk factor and disease outcome. The last two years have seen an increase in the number of MR studies investigating the relationship between anthropometric traits and metabolic diseases. This review provides an overview of these recent MR studies in relation to type 2 diabetes, coronary artery disease and hypertension. MR provides evidence for causal associations of waist-to-hip-ratio, body mass index and altered glucose levels with type 2 diabetes, coronary artery disease and hypertension.

Performance of waist circumference and proposed cutoff levels for defining overweight and obesity in Nigerians

Background:

Waist circumference (WC) is a simple tool for measuring central obesity in routine clinic settings. Gender- and ethnic-specific optimal cutoff points for WC are encouraged for populations lacking such data.

Objectives:

To derive WC cutoff values, predictive of overweight and obesity in Nigerians and to evaluate the performance of currently recommended values.

Subjects and Methods:

Apparently, healthy urban dwellers from six cities spread across Nigeria were selected for this cross-sectional study. Biophysical profiles such as blood pressure and anthropometric indices were measured according to the World Health Organization's STEPs instrument protocol. Receiver operating characteristics curve analysis was used to determine the optimal cutoff levels using the decision rule of maximum (sensitivity + specificity). The level of significance was set at P < 0.05.

Results:

A total of 6089 subjects (3234 males and 2855 females) were recruited for the study. WC demonstrated a high area under the curve in both genders. Selected cutoff points ranged from 83 to 96 cm with high sensitivities and specificities.

Conclusions:

The currently recommended gender-specific WC cutoff values proved inappropriate in this study group, but WC remains a reliable tool for measuring obesity.

Age- and sex-specific causal effects of adiposity on cardiovascular risk factors

Observational studies have reported different effects of adiposity on cardiovascular risk factors across age and sex. Since cardiovascular risk factors are enriched in obese individuals, it has not been easy to dissect the effects of adiposity from those of other risk factors. We used a Mendelian randomization approach, applying a set of 32 genetic markers to estimate the causal effect of adiposity on blood pressure, glycemic indices, circulating lipid levels, and markers of inflammation and liver disease in up to 67,553 individuals. All analyses were stratified by age (cutoff 55 years of age) and sex. The genetic score was associated with BMI in both nonstratified analysis (P = 2.8 × 10(-107)) and stratified analyses (all P < 3.3 × 10(-30)). We found evidence of a causal effect of adiposity on blood pressure, fasting levels of insulin, C-reactive protein, interleukin-6, HDL cholesterol, and triglycerides in a nonstratified analysis and in the <55-year stratum. Further, we found evidence of a smaller causal effect on total cholesterol (P for difference = 0.015) in the ≥55-year stratum than in the <55-year stratum, a finding that could be explained by biology, survival bias, or differential medication. In conclusion, this study extends previous knowledge of the effects of adiposity by providing sex- and age-specific causal estimates on cardiovascular risk factors.

Adiposity measurements by BMI, skinfolds and dual energy X-ray absorptiometry in relation to risk markers for cardiovascular disease and diabetes in adult males

BACKGROUND

Choice of adiposity measure may be important in the evaluation of relationships between adiposity and risk markers for cardiovascular disease and diabetes.

AIM

We explored the strengths of risk marker associations with BMI, a simple measure of adiposity, and with measures provided by skinfold thicknesses and dual energy X-ray absorptiometry (DXA).

SUBJECTS AND METHODS

We evaluated in three subgroups of white males (n = 156-349), participating in a health screening program, the strengths of relationship between measures of total and regional adiposity and risk markers relating to blood pressure, lipids and lipoproteins, insulin sensitivity, and subclinical inflammation.

RESULTS

Independent of age, smoking, alcohol intake, and exercise, the strongest correlations with adiposity measures were seen with serum triglyceride concentrations and indices of insulin sensitivity, with strengths of association showing little difference between BMI and skinfold and DXA measures of total and percent body fat (R = 0.20-0.46, P < 0.01). Significant but weaker associations with adiposity were seen for serum HDL cholesterol and only relatively inconsistent associations with adiposity for total and LDL cholesterol and indices of subclinical inflammation.

CONCLUSIONS

BMI can account for variation in risk markers in white males as well as more sophisticated measures derived from skinfold thickness measurements or DXA scanning.

Adiposity and insulin resistance in humans: the role of the different tissue and cellular lipid depots

Human adiposity has long been associated with insulin resistance and increased cardiovascular risk, and abdominal adiposity is considered particularly adverse. Intra-abdominal fat is associated with insulin resistance, possibly mediated by greater lipolytic activity, lower adiponectin levels, resistance to leptin, and increased inflammatory cytokines, although the latter contribution is less clear. Liver lipid is also closely associated with, and likely to be an important contributor to, insulin resistance, but it may also be in part the consequence of the lipogenic pathway of insulin action being up-regulated by hyperinsulinemia and unimpaired signaling. Again, intramyocellular triglyceride is associated with muscle insulin resistance, but anomalies include higher intramyocellular triglyceride in insulin-sensitive athletes and women (vs men). Such issues could be explained if the "culprits" were active lipid moieties such as diacylglycerol and ceramide species, dependent more on lipid metabolism and partitioning than triglyceride amount. Subcutaneous fat, especially gluteofemoral, appears metabolically protective, illustrated by insulin resistance and dyslipidemia in patients with lipodystrophy. However, some studies suggest that deep sc abdominal fat may have adverse properties. Pericardial and perivascular fat relate to atheromatous disease, but not clearly to insulin resistance. There has been recent interest in recognizable brown adipose tissue in adult humans and its possible augmentation by a hormone, irisin, from exercising muscle. Brown adipose tissue is metabolically active, oxidizes fatty acids, and generates heat but, because of its small and variable quantities, its metabolic importance in humans under usual living conditions is still unclear. Further understanding of specific roles of different lipid depots may help new approaches to control obesity and its metabolic sequelae.

Comparison of gross body fat-water magnetic resonance imaging at 3 Tesla to dual-energy X-ray absorptiometry in obese women

OBJECTIVE

Improved understanding of how depot-specific adipose tissue mass predisposes to obesity-related comorbidities could yield new insights into the pathogenesis and treatment of obesity as well as metabolic benefits of weight loss. We hypothesized that three-dimensional (3D) contiguous "fat-water" MR imaging (FWMRI) covering the majority of a whole-body field of view (FOV) acquired at 3 Tesla (3T) and coupled with automated segmentation and quantification of amount, type, and distribution of adipose and lean soft tissue would show great promise in body composition methodology.

DESIGN AND METHODS

Precision of adipose and lean soft tissue measurements in body and trunk regions were assessed for 3T FWMRI and compared to dual-energy X-ray absorptiometry (DXA). Anthropometric, FWMRI, and DXA measurements were obtained in 12 women with BMI 30-39.9 kg/m(2) .

RESULTS

Test-retest results found coefficients of variation (CV) for FWMRI that were all under 3%: gross body adipose tissue (GBAT) 0.80%, total trunk adipose tissue (TTAT) 2.08%, visceral adipose tissue (VAT) 2.62%, subcutaneous adipose tissue (SAT) 2.11%, gross body lean soft tissue (GBLST) 0.60%, and total trunk lean soft tissue (TTLST) 2.43%. Concordance correlation coefficients between FWMRI and DXA were 0.978, 0.802, 0.629, and 0.400 for GBAT, TTAT, GBLST, and TTLST, respectively.

CONCLUSIONS

While Bland-Altman plots demonstrated agreement between FWMRI and DXA for GBAT and TTAT, a negative bias existed for GBLST and TTLST measurements. Differences may be explained by the FWMRI FOV length and potential for DXA to overestimate lean soft tissue. While more development is necessary, the described 3T FWMRI method combined with fully-automated segmentation is fast (<30-min total scan and post-processing time), noninvasive, repeatable, and cost-effective.

DXA estimates of fat in abdominal, trunk and hip regions varies by ethnicity in men

Objective:

The aim of this study was to determine whether the quantity of fat is different across the central (that is, android, trunk) and peripheral (that is, arm, leg and gynoid) regions among young African-American (AA), Asian (AS), Hispanic (HI) and non-Hispanic White (NHW) men.

Subjects and Methods:

A cohort of 852 men (18–30 years; mean total body fat percent (TBF%)=18.8±7.9, range=3.7–45.4) were assessed for body composition in five body regions via dual-emission X-ray absorptiometry (DXA).

Results:

HI men (21.8±8.3) had higher TBF% than AA (17.0±10.0), NHW (17.9±7.2) and AS (18.9±8.0) groups (P-values <0.0001). AS had a lower BMI (23.9±3.4) than all other groups, and NHW (24.7±3.2) had a lower BMI than HI (25.7±3.9) and AA (26.5±4.7; P-values<0.0001). A linear mixed model (LMM) revealed a significant ethnicity by region fat% interaction (P<0.0001). HI men had a greater fat% than NHW for every region (adjusted means (%); android: 29.6 vs 23.3; arm: 13.3 vs 10.6; gynoid: 27.2 vs 23.8; leg: 21.2 vs 18.3; trunk: 25.5 vs 20.6) and a greater fat% than AA for every region except the arm. In addition, in the android and trunk regions, HI had a greater fat% than AS, and AS had a higher fat% than AA. Finally, the android fat% for AS was higher than that of NHW. When comparing the region fat% within ethnicities, the android region was greater than the gynoid region for AS and HI, but did not differ for AA and NHW, and the arm region had the least fat% in all ethnicities.

Conclusions:

Fat deposition and body fat patterning varies by ethnicity.

Relationships between body fat distribution, epicardial fat and obstructive sleep apnea in obese patients with and without metabolic syndrome

BACKGROUND

Obstructive sleep apnea (OSA) and metabolic syndrome, both closely related to obesity, often coexist in affected individuals; however, body mass index is not an accurate indicator of body fat and thus is not a good predictor of OSA and other comorbidities. The aim of this study was to investigate whether the occurrence of OSA could be associated with an altered body fat distribution and a more evident cardio metabolic risk independently from obesity and metabolic syndrome.

METHODS AND RESULTS

171 consecutive patients (58 men and 113 women) were included in the study and underwent overnight polysomnography. Anthropometric data, blood pressure, lipid profile, glycaemic parameters were recorded. Body composition by DXA, two-dimensional echocardiography and carotid intima/media thickness measurement were performed. 67 patients (39.2%) had no OSA and 104 (60.8%) had OSA. The percentage of patients with metabolic syndrome was significantly higher among OSA patients (65.4%) that were older, heavier and showed a bigger and fatter heart compared to the control group. Upper body fat deposition index , the ratio between upper body fat (head, arms and trunk fat in kilograms) and lower body fat (legs fat in kilograms), was significantly increased in the OSA patients and significantly related to epicardial fat thickness. In patients with metabolic syndrome, multivariate regression analyses showed that upper body fat deposition index and epicardial fat showed the best association with OSA.

CONCLUSION

The occurrence of OSA in obese people is more closely related to cardiac adiposity and to abnormal fat distribution rather than to the absolute amount of adipose tissue. In patients with metabolic syndrome the severity of OSA is associated with increase in left ventricular mass and carotid intima/media thickness.

Sex dimorphism in the association of cardiometabolic characteristics and osteophytes-defined radiographic knee osteoarthritis among obese and non-obese adults: NHANES III

OBJECTIVE

To examine the relationship of knee osteoarthritis (OA) with cardiovascular and metabolic risk factors by obesity status and gender.

METHODS

Data from 1,066 National Health and Nutrition Examination Survey III participants (≥60 years of age) was used to examine relationships of osteophytes-defined radiographic knee OA and cardiovascular and metabolic measures. Analyses were considered among obese [body mass index (BMI)≥30 kg/m(2)] and non-obese (BMI<30 kg/m(2)) men and women.

RESULTS

The prevalence of osteophytes-defined radiographic knee OA was 34%. Leptin levels and homeostatic model assessment-insulin resistance (HOMA-IR), a proxy measure of insulin resistance, were significantly associated with knee OA; those with knee OA had 35% higher HOMA-IR values and 52% higher leptin levels compared to those without knee OA. The magnitude of the association between HOMA-IR and knee OA was strongest among men, regardless of obesity status; odds ratios (ORs) for HOMA-IR were 34% greater among non-obese men (OR=1.18) vs obese women (OR=0.88). Among obese women, a 5-μg/L higher leptin was associated with nearly 30% higher odds of having knee OA (OR=1.28). Among men, ORs for the association of leptin and knee OA were in the opposite direction.

CONCLUSIONS

Cardiometabolic dysfunction is related to osteophytes-defined radiographic knee OA prevalence and persists within subgroups defined by obesity status and gender. A sex dimorphism in the direction and magnitude of cardiometabolic risk factors with respect to knee OA was described including HOMA-IR being associated with OA prevalence among men while leptin levels were most important among women.

Body adiposity and type 2 diabetes: increased risk with a high body fat percentage even having a normal BMI

Obesity is the major risk factor for the development of prediabetes and type 2 diabetes. BMI is widely used as a surrogate measure of obesity, but underestimates the prevalence of obesity, defined as an excess of body fat. We assessed the presence of impaired glucose tolerance or impaired fasting glucose (both considered together as prediabetes) or type 2 diabetes in relation to the criteria used for the diagnosis of obesity using BMI as compared to body fat percentage (BF%). We performed a cross-sectional study including 4,828 (587 lean, 1,320 overweight, and 2,921 obese classified according to BMI) white subjects (66% females), aged 18-80 years. BMI, BF% determined by air-displacement plethysmography (ADP) and conventional blood markers of glucose metabolism and lipid profile were measured. We found a higher than expected number of subjects with prediabetes or type 2 diabetes in the obese category according to BF% when the sample was globally analyzed (P < 0.0001) and in the lean BMI-classified subjects (P < 0.0001), but not in the overweight or obese-classified individuals. Importantly, BF% was significantly higher in lean (by BMI) women with prediabetes or type 2 diabetes as compared to those with normoglycemia (NG) (35.5 ± 7.0 vs. 30.3 ± 7.7%, P < 0.0001), whereas no differences were observed for BMI. Similarly, increased BF% was found in lean BMI-classified men with prediabetes or type 2 diabetes (25.2 ± 9.0 vs. 19.9 ± 8.0%, P = 0.008), exhibiting no differences in BMI or waist circumference. In conclusion, assessing BF% may help to diagnose disturbed glucose tolerance beyond information provided by BMI and waist circumference in particular in male subjects with BMI <25 kg/m(2) and over the age of 40.

Comparison of dual-energy x-ray absorptiometric and anthropometric measures of adiposity in relation to adiposity-related biologic factors

Dual-energy x-ray absorptiometry (DXA) can provide accurate measurements of body composition. Few studies have compared the relative validity of DXA measures with anthropometric measures such as body mass index (BMI) and waist circumference (WC). The authors compared correlations of DXA measurements of total fat mass and fat mass percent in the whole body and trunk, BMI, and WC with obesity-related biologic factors, including blood pressure and levels of plasma lipids, C-reactive protein, and fasting insulin and glucose, among 8,773 adults in the National Health and Nutrition Examination Survey (1999-2004). Overall, the magnitudes of correlations of BMI and WC with the obesity-related biologic factors were similar to those of fat mass or fat mass percent in the whole body and trunk, respectively. These observations were largely consistent across different age, gender, and ethnic groups. In addition, in both men and women, BMI and WC demonstrated similar abilities to distinguish between participants with and without the metabolic syndrome in comparison with corresponding DXA measurements. These data indicate that the validity of simple anthropometric measures such as BMI and WC is comparable to that of DXA measurements of fat mass and fat mass percent, as evaluated by their associations with obesity-related biomarkers and prevalence of metabolic syndrome.

Imaging body composition in obesity and weight loss: challenges and opportunities

Obesity is a threat to public health worldwide primarily due to the comorbidities related to visceral adiposity, inflammation, and insulin resistance that increase risk for type 2 diabetes and cardiovascular disease. The translational research portfolio that originally described these risk factors was significantly enhanced by imaging techniques, such as dual-energy X-ray absorptiometry (DEXA), computed tomography (CT), and magnetic resonance imaging (MRI). In this article, we briefly review the important contributions of these techniques to understand the role of body composition in the pathogenesis of obesity-related complications. Notably, these imaging techniques have contributed greatly to recent findings identifying gender and racial differences in body composition and patterns of body composition change during weight loss. Although these techniques have the ability to generate good-quality body composition data, each possesses limitations. For example, DEXA is unable to differentiate type of fat, CT has better resolution but provides greater ionizing radiation exposure, and MRI tends to require longer imaging times and specialized equipment for acquisition and analysis. With the serious need for efficacious and cost-effective therapies to appropriately identify and treat at-risk obese individuals, there is greater need for translational tools that can further elucidate the interplay between body composition and the metabolic aberrations associated with obesity. In conclusion, we will offer our perspective on the evolution toward an ideal imaging method for body composition assessment in obesity and weight loss, and the challenges remaining to achieve this goal.

Relationship between surface facial dimensions and upper airway structures in obstructive sleep apnea

STUDY OBJECTIVES

We hypothesized that the facial phenotype is closely linked to upper airway anatomy. The aim of this study was to investigate the relationship between surface facial dimensions and upper airway structures using magnetic resonance imaging (MRI) in subjects with obstructive sleep apnea (OSA).

DESIGN

Cohort study.

SETTING

Sleep investigation unit.

PATIENTS

Sixty-nine patients (apnea-hypopnea index > or = 10/h) underwent MRI as part of a study of upper airway anatomy in oral appliance therapy.

INTERVENTIONS

Measurements of a range of surface facial dimensions and upper airway soft tissue volumes were performed on the MR images using image-analysis software. Pearson correlation analyses were performed.

MEASUREMENTS AND RESULTS

Significant correlations were identified between a number of surface facial dimensions and neck circumference. Significant positive correlations were demonstrated between surface facial dimensions (including facial widths, facial heights, nose width, interocular and intercanthal widths) and upper airway structures. The strongest associations were between the tongue volume and the midface width (r = 0.70, P < 0.001), and lower-face width (r = 0.60, P <0.001). Surface facial dimensions in combination were also strong determinants for tongue volume (r2 = 0.69). Correlations between surface soft tissue thickness and upper airway soft tissue volumes occurred at the level of the midface but not at the level of the lower face.

CONCLUSIONS

This study demonstrates that there is a relationship between surface facial dimensions and upper airway structures in subjects with OSA. These findings support the potential role of surface facial measurements in anatomic phenotyping for OSA.

Association of central adiposity with prediabetes and decreased insulin sensitivity in rural Chinese normal-weight and overweight women

This study investigated whether high central adiposity was associated with prediabetes and decreased insulin sensitivity (IS) in both normal-weight (body mass index [BMI] <23 kg/m(2)) and overweight (BMI >or=23 kg/m(2)) rural Chinese women. Adipose variables measured by dual-energy x-ray absorptiometry (percentage body fat, percentage lower-body fat [%LF], and percentage trunk fat [%TF]) and general adipose variables (BMI and waist circumference) were used for examining the association of adiposity with prediabetes among 4071 rural Chinese women aged 20 to 60 years. Furthermore, the association of adiposity with IS was tested in both normal- and overweight women with normal glucose tolerance. BMI was highly correlated with percentage body fat and waist circumference, but was weakly correlated with %LF and %TF. Both high %TF (top quartile of %TF) and low %LF (lower 3 quartiles of %LF) were associated with higher prevalence of prediabetes in both normal- and overweight women. Compared with normal-weight women in low %TF, the odds of prediabetes were similarly increased for women with high %TF regardless of whether they were overweight (odds ratio [95% confidence interval] = 1.6 [1.3-2.0]) or not (odds ratio [95% confidence interval] = 1.5 [1.2-2.0]). Similarly, among 3280 women with normal glucose tolerance, high %TF was associated with increased fasting insulin, 2-hour oral glucose tolerance test insulin, and homeostasis model assessment of insulin resistance regardless of weight status (normal or overweight). Among relatively lean, rural Chinese women, high %TF was associated with increased odds of prediabetes and lower IS regardless of weight status (normal or overweight).

Obesity and risk of pancreatic cancer among postmenopausal women: the Women's Health Initiative (United States)

A total of 138 503 women in the Women's Health Initiative in the United States were followed (for an average of 7.7 years) through 12 September 2005 to examine obesity, especially central obesity in relation to pancreatic cancer (n=251). Women in the highest quintile of waist-to-hip ratio had 70% (95% confidence interval 10–160%) excess risk of pancreatic cancer compared with women in the lowest quintile.

Eating meals irregularly: a novel environmental risk factor for the metabolic syndrome

BACKGROUND

Skipping meals is a common practice in our current society; however, it is not clear whether eating meals regularly is associated with the metabolic syndrome.

OBJECTIVE

Our aim was to assess the association of eating meals regularly with parameters of the metabolic syndrome and insulin resistance in a representative population-based cohort of 60-year-old men and women.

METHODS AND PROCEDURES

A population-based cross-sectional study of 3,607 individuals (1,686 men and 1,921 women), aged 60 years, was conducted in Stockholm County, Sweden. Medical history, socioeconomic factors, and lifestyle data were collected by a questionnaire and a medical examination, which included laboratory tests.

RESULTS

Of the subjects who were regular eaters, 20% fulfilled the criteria for the metabolic syndrome vs. 27% of subjects who were irregular eaters (P < 0.0001). The adjusted odds ratio (OR) for having the greatest number of components of the metabolic syndrome in subjects who were regular eaters was 0.27 (95% confidence interval (CI), 0.13-0.54) using subjects who did not fulfill any criteria for the metabolic syndrome as a reference group. Eating meals regularly was also inversely related to insulin resistance (OR, 0.68 (95% CI, 0.48-0.97)) and to gamma-glutamyl transferase (OR, 0.52 (95% CI, 0.33-83)) after full adjustment.

DISCUSSION

Eating meals regularly is inversely associated to the metabolic syndrome, insulin resistance and (high) serum concentrations of gamma-glutamyl transferase. These findings suggest that eating meals irregularly may be part of several potential environmental risk factors that are associated with the metabolic syndrome and may have future implications in giving dietary advice to prevent and/or treat the syndrome.

Simple anthropometric measures correlate with metabolic risk indicators as strongly as magnetic resonance imaging-measured adipose tissue depots in both HIV-infected and control subjects

BACKGROUND

Studies in persons without HIV infection have compared percentage body fat (%BF) and waist circumference as markers of risk for the complications of excess adiposity, but only limited study has been conducted in HIV-infected subjects.

OBJECTIVE

We compared anthropometric and magnetic resonance imaging (MRI)-based adiposity measures as correlates of metabolic complications of adiposity in HIV-infected and control subjects.

DESIGN

The study was a cross-sectional analysis of 666 HIV-positive and 242 control subjects in the Fat Redistribution and Metabolic Change in HIV Infection (FRAM) study assessing body mass index (BMI), waist (WC) and hip (HC) circumferences, waist-to-hip ratio (WHR), %BF, and MRI-measured regional adipose tissue. Study outcomes were 3 metabolic risk variables [homeostatic model assessment (HOMA), triglycerides, and HDL cholesterol]. Analyses were stratified by sex and HIV status and adjusted for demographic, lifestyle, and HIV-related factors.

RESULTS

In HIV-infected and control subjects, univariate associations with HOMA, triglycerides, and HDL were strongest for WC, MRI-measured visceral adipose tissue, and WHR; in all cases, differences in correlation between the strongest measures for each outcome were small (r

CONCLUSION

Relations of simple anthropometric measures with HOMA, triglycerides, and HDL cholesterol are approximately as strong as MRI-measured whole-body adipose tissue depots in both HIV-infected and control subjects.

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Key Words Collapse

MESH Headings

• Adipose Tissue/anatomy & histology
• Adult
• Anthropometry/methods
• Body Mass Index
• Body Size
• Cross-Sectional Studies
• Female
• HIV Infections/complications
• HIV Infections/epidemiology
• Humans
• Magnetic Resonance Imaging/methods
• Male
• Middle Aged
• Patient Selection
• Predictive Value of Tests
• Reference Values
• Risk Assessment
• Waist-Hip Ratio

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Grants

• HL74814 NHLBI NIH HHS
• R01 HL074814-06 NHLBI NIH HHS
• R01 DK057508-03S1 NIDDK NIH HHS
• M01 RR000054 NCRR NIH HHS
• RR00052 NCRR NIH HHS
• RR0636 NCRR NIH HHS
• M01 RR000083 NCRR NIH HHS
• RR00054 NCRR NIH HHS
• R01 DK057508-03 NIDDK NIH HHS
• R01 DK057508-01S1 NIDDK NIH HHS
• RR00865 NCRR NIH HHS
• R01-DK57508 NIDDK NIH HHS
• R01 DK057508 NIDDK NIH HHS
• R01 HL074814-07 NHLBI NIH HHS
• R01 DK057508-01 NIDDK NIH HHS
• RR00083 NCRR NIH HHS
• M01 RR000865 NCRR NIH HHS
• M01 RR000036 NCRR NIH HHS
• HL 53359 NHLBI NIH HHS
• R01 HL074814-04 NHLBI NIH HHS
• RR00051 NCRR NIH HHS
• R01 DK057508-03S2 NIDDK NIH HHS
• M01 RR000052 NCRR NIH HHS
• R01 HL074814-05 NHLBI NIH HHS
• M01 RR000051 NCRR NIH HHS
• M01-RR00036 NCRR NIH HHS
• R01 HL074814 NHLBI NIH HHS
• R01 DK057508-02 NIDDK NIH HHS

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Affiliation(s)

Rebecca Scherzer Northern California Institute for Research and Education, San Francisco, CA, USA
Wei Shen
Peter Bacchetti
Donald Kotler
Cora E Lewis
Michael G Shlipak
Steven B Heymsfield
Carl Grunfeld

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Relationship of abdominal obesity measured by DXA and waist circumference with insulin sensitivity in Hispanic and non-Hispanic white individuals: the San Luis Valley Diabetes Study

BACKGROUND

To determine if dual-energy X-ray absorptiometry (DXA) measures of trunk fat, a user-defined abdominal region of interest (ROI) and waist circumference (WC) differ in their association with insulin sensitivity among Hispanics and non-Hispanic whites (NHW) or explain any ethnic differences in insulin sensitivity.

METHODS

A cross-sectional study of data collected (1997-98) as part of the longitudinal San Luis Valley Diabetes Study was utilized. There were 664 non-diabetic participants including 349 women (220 NHW, 139 Hispanic) and 305 men (197 NHW, 108 Hispanic), average age 63 years. Measurements included body mass index, WC and DXA measures of total and abdominal fat. Fasting glucose and insulin were used to estimate insulin sensitivity using the QUICKI index. A 2-h oral glucose tolerance test was used to classify participants with normal glucose tolerance (NGT) or impaired glucose tolerance (IGT).

RESULTS

Among women with NGT, Hispanics had lower insulin sensitivity, with DXA trunk fat explaining the most variance in QUICKI and 54% of the ethnic difference in QUICKI after adjusting for total body fat and lean mass. Among men with NGT, there were no differences between Hispanics and NHW in insulin sensitivity or any differences in the association of the abdominal fat measures with insulin sensitivity. Among men and women with IGT, the fat distribution variables explained little variance in QUICKI.

CONCLUSIONS

DXA measures of trunk fat provide additional information over WC and the DXA abdominal ROI measure about ethnic differences in insulin sensitivity between older Hispanic and NHW women with NGT.

Sex differences in fat storage, fat metabolism, and the health risks from obesity: possible evolutionary origins

Human beings are susceptible to sustained weight gain in the modern environment. Although both men and women can get fat, they get fat in different ways, and suffer different consequences. We review differences between men and women in the incidence of obesity, fat deposition patterns, fat metabolism, and the health consequences of obesity, and examine potential evolutionary explanations for these differences. Women generally have a larger proportion of body mass as fat, and are more likely to deposit fat subcutaneously and on their lower extremities; men are more likely to deposit fat in the abdominal region. Excess adipose tissue in the abdominal region, especially visceral fat, is associated with more health risks. Women have higher rates of reuptake of NEFA into adipose tissue; however, they also have higher rates of fat oxidation during prolonged exercise. Oestrogen appears to underlie many of these differences. Women bear higher nutrient costs during reproduction. Fat and fertility are linked in women, through leptin. Low leptin levels reduce fertility. Ovarian function of adult women is associated with their fatness at birth. In our evolutionary past food insecurity was a frequent occurrence. Women would have benefited from an increased ability to store fat in easily metabolisable depots. We suggest that the pattern of central obesity, more commonly seen in men, is not adaptive, but rather reflects the genetic drift hypothesis of human susceptibility to obesity. Female obesity, with excess adiposity in the lower extremities, reflects an exaggeration of an adaptation for female reproductive success.

Sexual dimorphism of body composition

Sexual dimorphism in human body composition is evident from fetal life, but emerges primarily during puberty. At birth, males have a similar fat mass to females but are longer and have greater lean mass. Such differences remain detectable during childhood; however, females enter puberty earlier and undergo a more rapid pubertal transition, whereas boys have a substantially longer growth period. After adjusting for dimorphism in size (height), adult males have greater total lean mass and mineral mass, and a lower fat mass than females. These whole-body differences are complemented by major differences in tissue distribution. Adult males have greater arm muscle mass, larger and stronger bones, and reduced limb fat, but a similar degree of central abdominal fat. Females have a more peripheral distribution of fat in early adulthood; however, greater parity and the menopause both induce a more android fat distribution with increasing age. Sex differences in body composition are primarily attributable to the action of sex steroid hormones, which drive the dimorphisms during pubertal development. Oestrogen is important not only in body fat distribution but also in the female pattern of bone development that predisposes to a greater female risk of osteoporosis in old age. Disorders of sex development are associated with significant abnormalities of body composition, attributable largely to their impact on mechanisms of hormonal regulation.

Relation of increased leptin concentrations to history of myocardial infarction and stroke in the United States population

Leptin, an adipose tissue-derived hormone, has been linked to cardiovascular outcomes; however, data are limited in the United States population, especially women. To assess the association between leptin concentrations and history of myocardial infarction (MI) and stroke independently of traditional cardiovascular risk factors, we analyzed data from 6,239 subjects (mean age 47 years; 3,336 women) with measurements of serum leptin and full assessment of cardiovascular risk factors from the National Health and Nutrition Examination Survey (NHANES) III. Logistic regression was used to estimate the cross-sectional association of leptin concentrations (highest quartile versus lowest quartile) and history of MI, stroke, and the composite end point of MI or stroke (MI/stroke). Gender-specific models of leptin were adjusted for age, race, dyslipidemia, hypertension, diabetes, smoking, and obesity status. There were 212 men with MI/stroke (5.4%), 154 with MI (4.1%), and 82 with stroke (1.7%). There were 135 women with MI/stroke (2.6%), 74 with MI (1.5%), and 78 with stroke (1.4%). In multivariate analysis, high leptin level was significantly and independently associated with MI/stroke in men (odds ratio [OR] 2.41, 95% confidence interval [CI] 1.20 to 4.93) and women (OR 4.26, 95% CI 1.75 to 10.73); with MI in men (OR 3.16, 95% CI 1.40 to 7.37) and women (OR 3.96, 95% CI 1.29 to 12.72), and with stroke in women (OR 3.20, 95% CI 1.04 to 10.54) but not in men (OR 1.37, 95% CI 0.38 to 3.88). In conclusion, in the United States population, increased leptin concentrations are significantly associated with MI/stroke in men and women independently of traditional cardiovascular risk factors and obesity status.

Correspondence between the adult treatment panel III criteria for metabolic syndrome and insulin resistance

OBJECTIVE

The aim of the present study was to assess the diagnostic accuracy of the Adult Treatment Panel III (ATP-III) definition of the metabolic syndrome in identifying insulin-resistant individuals and to explore alternative approaches to improve identification of insulin-resistant individuals among asymptomatic adults from the general population.

RESEARCH DESIGN AND METHODS

The sample consisted of 256 non-Hispanic white subjects without treated hypertension or diabetes, from the Rochester (Minnesota) Heart Family Study (123 men and 133 women; aged 20-60 years). Frequently sampled intravenous glucose tolerance tests were performed in all subjects. The reference standard for insulin resistance was determined by Bergman's minimal model; insulin resistance was defined as an insulin sensitivity index <2 x 10 min(-1) . microU(-1) . ml(-1). Component metabolic syndrome measures included blood pressure determined by sphygmomanometer; fasting serum triglycerides, HDL cholesterol, and glucose concentrations determined enzymatically; and waist circumference determined by tape measure.

RESULTS

By ATP-III criteria, the prevalence of metabolic syndrome was 15.6% (16.3% in men and 15.1% in women; P = 0.465). The presence of metabolic syndrome had low sensitivity to identify insulin resistance (45% in men and 39% in women; sex difference, P = 0.137) but high specificity (93% in men and 95% in women; sex difference, P = 0.345). Based on the area under the receiver operating characteristic curve (AUC) constructed by counting metabolic syndrome components as recommended by ATP-III, diagnostic accuracy was fair (AUC = 0.797 in men and 0.747 in women). When component metabolic syndrome measures were considered as quantitative traits rather than dichotomized, use of waist circumference alone, rather than counting metabolic syndrome components, improved diagnostic accuracy for insulin resistance (in men, AUC = 0.906, P = 0.001; in women, AUC = 0.822, P = 0.10).

CONCLUSIONS

Application of the ATP-III metabolic syndrome criteria provides good specificity but low sensitivity to screen asymptomatic white adults for insulin resistance. Measuring just waist circumference is simpler and may provide greater accuracy for identifying insulin resistance.