Aging and changes in adiposity indices: the impact of menopause

PURPOSE

Aging is associated with significant changes in fat distribution and menopause may alter this process. This study aimed to investigate the longitudinal effect of menopause on changes in adiposity indices (AI).

METHODS

A total number of 3876 non-menopausal women, aged > 20 years, who participated in the Tehran Lipid and Glucose study, were selected for the present study. They were followed from 1998 to 2018 at a 3-year interval and their adiposity indices were measured. Throughout the study, participants were categorized into two groups according to their menopausal status as group 1): women who reached menopause and group 2): women who did not reach menopause. The generalized estimation equation (GEE) models were used to compare the trend of changes in AIs between these two groups.

RESULTS

At the end of the study, a total number of 1479 (38.2%) participants reached menopause. The odds of general obesity decreased by 5% (OR: 0.95, 95% CI: 0.90-0.99), and the odds of central obesity increased by 6% in group1 compared to group2 (OR: 1.06, 95% CI: 1.01-1.12).

CONCLUSIONS

Menopause alters the impact of aging on central fat distribution. Increasing awareness of the related risk in menopausal women and their healthcare professional may prevent adverse related outcomes.

Comparison of pancreatic fat content measured by different methods employing MR mDixon sequence

Objective

To compare the reliability of different methods for measuring fat content of pancreas by MR modified Dixon(mDixon) Sequence and accurately evaluate pancreatic fat in as simple a way as possible.

Methods

This is a retrospective study, 64 patients were included in this study who underwent abdominal MR scan that contained the mDixon sequence from June 2019 to May 2020(Included 7 patients with type 2 diabetes and 4 patients with impaired glucose tolerance (IGT), they were admitted to hospital through the obesity clinic set up by endocrine department, all of them were initially diagnosed and untreated). All of the 64 patients were scanned in 3.0T MR (Philips Ingenia II) due to their condition, 10–34 slice pancreas images were obtained, which were different from each other. Three different methods of measurement were employed by two observers using Philips Intellispace Portal software: (1) All images (whole-pancreas) measurement, the whole-pancreatic fat fraction (wPFF) was calculated by software. (2) Interval slices measurement, that is half-pancreatic slices fat fraction (hPFF) measured in the same way, fat fraction obtained by the interlayer assay was calculated. (3) As usual, the fat content of pancreatic head, body and tail fat was measured respectively, and in order to improve credibility, we also measured head、 body and tail in every layer, and its average value was taken. The elapsed time of the above different measurement methods was recorded. Intra-group correlation coefficient (ICC) was used to analyze the consistency of the measured data within and between observers. T-tests and Friedman tests were applied to compare the difference of measuredvalues among groups.

Results

No matter in normal person or diabetic or IGT, hPFF has shown good stability (ICChPFF = 0.988), and there was no significant difference compared with wPFF. But the average fat percentage composition of head, body and tail were significantly different from wPFF and hPFF (P < 0.01). At the same time, compared with normal person, pancreatic fat content in IGT and diabetic patients showed progressive significance(P<0.05).

Conclusion

The distribution of pancreatic fat is not uniform, the method of measuring half pancreas by interlayer data collection can reflect the fat content of the entire pancreas, this suggests that measuring 50% of the pancreas is sufficient, this method effectively saves time and effort without affecting the results, which may have a better clinical application prospect.

Relationships of Physical Activity and Diet Quality with Body Composition and Fat Distribution in US Adults

OBJECTIVE

This study aimed to investigate the relationships among physical activity (PA), diet quality, body composition, and fat distribution in a representative sample of US adults.

METHODS

A cross-sectional analysis was conducted using publicly accessible data from the 2011 to 2016 National Health and Nutrition Examination Survey and the Food Patterns Equivalents Database (n = 7,423). Variables from the data sets were analyzed for this study, including PA, two 24-hour dietary recalls, and dual-energy x-ray absorptiometry outputs.

RESULTS

For men, PA and diet quality were inversely associated with the percentage of body fat (β = -0.0042, 95% CI: -0.0084 to -0.0001; β = -0.28, 95% CI: -0.42 to -0.14) and fat mass index (β = -0.0125, 95% CI: -0.0209 to -0.0041; β = -0.56, 95% CI: -0.81 to -0.32); meeting the PA recommendation and having good diet quality provided an additive effect on body fat. A similar pattern was observed in women. Additionally, diet quality was inversely associated with all fat distribution measures in both sexes, whereas PA was positively associated with lean mass measures in men only.

CONCLUSIONS

Increased PA and/or better diet quality were associated with reduced body fat, a healthier fat distribution, and increased lean mass. Further research examining how changes in PA or diet quality influence body composition and fat distribution in adults is warranted.

RNA-Seq based genetic variant discovery provides new insights into controlling fat deposition in the tail of sheep

Genetic basis of fat deposition in sheep tail have not been completely elucidated yet. Understanding the genetic mechanisms controlling fat-tail size can improve breeding strategies to modulate fat deposition. RNA sequencing has made it possible to discover genetic variants that may underlie various phenotypic differences. Hence, to identify genetic variants that are important for describing different fat-tail phenotypes in sheep, RNA sequencing was used for single nucleotide polymorphism (SNP) calling in two Iranian sheep breeds (Lori-Bakhtiari, fat-tailed; n = 4, vs Zel, thin-tailed; n = 4). Using a stringent pipeline, a total of 112,344 known SNPs were genotyped, of which 30,550 and 42,906 SNPs were shared by at least two Lori-Bakhtiari and Zel, respectively. Comparing these SNPs showed 2,774 (including 209 missense and 25 deleterious SNPs) and 10,470 (including 1,054 missense and 116 deleterious SNPs) breed-specific SNPs in Lori-Bakhtiari and Zel sheep, respectively. Potential breed-specific SNPs were detected by considering those located in QTL regions associated with fatness or reported as important candidates in previous similar studies. Of the breed-specific SNPs, 724 and 2,905 were located in the QTL regions. Functional enrichment analysis of the affected genes revealed several enriched gene ontologies and KEGG pathways related to fat metabolism. Based on the results, several affected genes were proposed to be strongly linked with fat deposition such as DGAT2, ACSL1, ACACA, ADIPOQ, ACLY, FASN, CPT2, SCD, ADCY6, PER3, CSF1R, SLC22A4, GFPT1, CDS2, BMP6, ACSS2, ELOVL6, HOXA10 and FABP4. Moreover, several SNPs were found in the candidate genes related to fatty acid oxidation introducing them as promising candidates responsible for lower fat content in tail of Zel. Our findings provided new insights into the genetic mechanisms of fat deposition in sheep, which can serve to designing appropriate breeding programs.

In Vivo Investigation of High-Fat Diet-Induced Hepatic Lipid Dysfunctions

Fat distribution, on top of general obesity, contributes to the severity of histologic features in patients with nonalcoholic fatty liver diseases (NAFLD); and visceral obesity has been correlated to fatty liver diseases. Therefore, investigation of fat distribution in vivo could be a good predictor of fatty liver risks in obesity. Fatty acids composition is a key player in hepatic dysfunctions and cardiovascular risk in obesity. Because fatty acids can damage biological membranes, fatty acid accumulation in the liver may be partially responsible for the functional and morphological changes that are observed in NAFLD. Fatty acids stored into triglycerides are lipid species that act as signaling molecules and therefore are key regulators of posttranslational regulation of biological functions such as lipid homeostasis and lipotoxicity. Here, we describe magnetic resonance methods to investigate in vivo whole-body fat distribution and hepatic liver fatty acid composition in order to directly assess the liver metabolic status and may allow to anticipate liver diseases.

Titrating Growth Hormone Dose to High-Normal IGF-1 Levels Has Beneficial Effects on Body Fat Distribution and Microcirculatory Function Despite Causing Insulin Resistance

To clarify the mechanism underlying the described U-shaped relation of both low and high levels of IGF-1 with cardiovascular disease this study explores the effect of decreasing and increasing growth hormone dose in GH deficient adults on (micro)vascular function, body composition and insulin resistance. In this randomized clinical trial, thirty-two subjects receiving GH therapy with an IGF-1 concentration between -1 and 1 SD score (SDS) for at least one year were randomized to receive either a decrease (IGF-1 target level of -2 to -1 SDS) or an increase of their daily GH dose (IGF-1 target level of 1 to 2 SDS) for a period of 24 weeks. Microvascular endothelium (in)dependent vasodilatation and vasomotion, vascular stiffness by pulse wave analysis, and HOMA-IR were measured. At the end of the study 30 subjects (65.6% men, mean age 46.6 (SD 9.9) years) were analyzed. There was a favorable effect of increasing the IGF-1 level on waist circumference compared to decreasing the IGF-1 level (p=0.05), but a detrimental effect on insulin resistance (p=0.03). Decreasing IGF-1 level significantly lowered the endothelial domain of vasomotion (p=0.03), whereas increasing IGF-1 level increased the contribution of the neurogenic domain (p=0.05). This change was related to the favorable change in waist circumference. In conclusion, increasing IGF-1 levels was beneficial for body composition but detrimental with respect to insulin resistance. The contribution of the neurogenic vasomotion domain increased in parallel, and could be explained by the favorable change in waist circumference.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, identifier NCT01877512.

Subcutaneous adipose tissue free fatty acid uptake measured using positron emission tomography and adipose biopsies in humans

Positron emission tomography (PET) radiopharmaceuticals can noninvasively measure free fatty acid (FFA) uptake into adipose tissue. We studied 29 volunteers to test whether abdominal and femoral subcutaneous adipose tissue FFA uptake measured using [1-¹¹C]palmitate PET agrees with FFA storage rates measured using an intravenous bolus of [1-¹⁴C]palmitate and adipose biopsies. The dynamic left ventricular cavity PET images combined with blood sample radioactivity corrected for the ¹¹CO₂ content were used to create the blood time activity curve (TAC), and the constant (K_i) was determined using Patlak analysis of the TACs generated for regions of interest in abdominal subcutaneous fat. These data were used to calculate palmitate uptake rates in abdominal subcutaneous adipose tissue (µmol·kg^-1·min^-1). Immediately after the dynamic imaging, a static image of the thigh was taken to measure the standardized uptake value (SUV) in thigh adipose tissue, which was scaled to each participant's abdominal adipose tissue SUV to calculate thigh adipose palmitate uptake rates. Abdominal adipose palmitate uptake using PET [1-¹¹C]palmitate was correlated with, but significantly (P < 0.001) greater than, FFA storage measured using [1-¹⁴C]palmitate and adipose biopsy. Thigh adipose palmitate measured using PET calculation was positively correlated (R² = 0.44, P < 0.0001) with and not different from the biopsy approach. The relative differences between PET measured abdominal subcutaneous adipose tissue palmitate uptake and biopsy-measured palmitate storage were positively correlated (P = 0.03) with abdominal subcutaneous fat. We conclude that abdominal adipose tissue FFA uptake measured using PET does not equate to adipose FFA storage measured using biopsy techniques.

Lower Leg Fat Depots Are Associated with Albuminuria Independently of Obesity, Insulin Resistance, and Metabolic Syndrome (Korea National Health and Nutrition Examination Surveys 2008 to 2011)

BACKGROUND

Although the involvement of obesity in metabolic disorders is well known, leg fat depot influences on albuminuria have not been determined.

METHODS

This population-based, cross-sectional study used a nationally representative sample of 2,076 subjects aged ≥20 years from the Korea National Health and Nutrition Examination Surveys of 2008 to 2011. The ratio of leg fat to total fat (LF/TF ratio) was assessed by dual X-ray absorptiometry, and albuminuria was defined as more than one positive dipstick test or an albumin-to-creatinine ratio of ≥30 mg/g.

RESULTS

Individuals whose LF/TF ratio was in the lowest tertile showed a higher proportion of albuminuria than those in the highest tertile (odds ratio [OR], 2.82; 95% confidence interval [CI], 2.01 to 3.96; P<0.001). This association was observed in both sexes, all age groups, and all subgroups stratified by body mass index, waist circumference, homeostasis model assessments of insulin resistance, and the presence of metabolic syndrome (all, P<0.05). Multiple logistic regression analyses also demonstrated that the lowest LF/TF ratio was independently associated with albuminuria risk (OR, 1.55 to 2.16; all, P<0.05). In addition, the risk of albuminuria was higher in sarcopenic individuals with lower LF/TF ratios than in the highest LF/TF ratio subjects without sarcopenia (OR, 3.73; 95% CI, 2.26 to 6.13).

CONCLUSION

A lower LF/TF ratio was associated with an increased risk of albuminuria independent of obesity, insulin resistance, and metabolic syndrome, and when combined with sarcopenia, the albuminuria risk synergistically increased. Hence, our findings may have implications to improve risk stratification and recommendations on body fat distribution in the general population.

Body Fat Distribution and Systolic Blood Pressure in 10,000 Adults with Whole-Body Imaging: UK Biobank and Oxford BioBank

OBJECTIVE

This study aimed to quantify the associations of regional fat mass and fat-free mass with systolic blood pressure.

METHODS

This analysis combined individual participant data from two large-scale imaging studies: UK Biobank and Oxford BioBank. In both studies, participants were interviewed and measured, and they underwent dual-energy x-ray absorptiometry imaging. Linear regression was used to relate systolic blood pressure to anthropometric measures of adiposity (BMI, waist circumference, and waist to hip ratio) and dual-energy x-ray absorptiometry-derived measures of body composition (visceral android fat, subcutaneous android fat, subcutaneous gynoid fat, and fat-free mass).

RESULTS

Among 10,260 participants (mean age 49; 96% white), systolic blood pressure was positively associated with visceral android fat (3.2 mmHg/SD in men; 2.8 mmHg/SD in women) and fat-free mass (1.92 mmHg/SD in men; 1.64 mmHg/SD in women), but there was no evidence of an association with subcutaneous android or gynoid fat. Associations of systolic blood pressure with BMI were slightly steeper than those with waist circumference or waist to hip ratio; these associations remained unchanged following adjustment for fat-free mass, but adjustment for visceral android fat eliminated associations with waist circumference and waist to hip ratio and more than halved associations with BMI.

CONCLUSIONS

This analysis indicates that visceral fat is the primary etiological component of excess adiposity underlying the development of adiposity-related hypertension.

Protein-coding variants implicate novel genes related to lipid homeostasis contributing to body-fat distribution

Body-fat distribution is a risk factor for adverse cardiovascular health consequences. We analyzed the association of body-fat distribution, assessed by waist-to-hip ratio adjusted for body mass index, with 228,985 predicted coding and splice site variants available on exome arrays in up to 344,369 individuals from five major ancestries (discovery) and 132,177 European-ancestry individuals (validation). We identified 15 common (minor allele frequency, MAF ≥5%) and nine low-frequency or rare (MAF <5%) coding novel variants. Pathway/gene set enrichment analyses identified lipid particle, adiponectin, abnormal white adipose tissue physiology and bone development and morphology as important contributors to fat distribution, while cross-trait associations highlight cardiometabolic traits. In functional follow-up analyses, specifically in Drosophila RNAi-knockdowns, we observed a significant increase in the total body triglyceride levels for two genes (DNAH10 and PLXND1). We implicate novel genes in fat distribution, stressing the importance of interrogating low-frequency and protein-coding variants.

Prediction of Circulating Adipokine Levels Based on Body Fat Compartments and Adipose Tissue Gene Expression

BACKGROUND

Adipokines are hormones secreted from adipose tissue (AT), and a number of them have been established as risk factors for chronic diseases. However, it is not clear whether and to what extent adiposity, gene expression, and other factors determine their circulating levels.

OBJECTIVES

To assess to what extent adiposity, as measured by the amount of subcutaneous AT (SAT) and visceral AT (VAT) using magnetic resonance imaging, and gene expression levels in SAT determine plasma concentrations of the adipokines adiponectin, leptin, soluble leptin receptor, resistin, interleukin 6, and fatty acid-binding protein 4 (FABP4).

METHODS

We performed a cross-sectional analysis of 156 participants from the EPIC Potsdam cohort study and analyzed multiple regression models and partial correlation coefficients.

RESULTS

For leptin and FABP4 concentrations, 81 and 45% variance were explained by SAT mass, VAT mass, and gene expression in SAT in multivariable regression models. For the remaining adipokines, AT mass and gene expression explained <16% variance of plasma concentrations. Gene expression in SAT was a less important predictor compared to AT mass. SAT mass was a better predictor than VAT mass for leptin (partial correlation r = 0.81, 95% confidence interval 0.75-0.86, vs. r = 0.58, 95% confidence interval 0.46-0.67), while differences between AT compartments were small for the other adipokines.

CONCLUSIONS

While plasma levels of leptin and FABP4 can be explained in a large and medium part by the amount of AT and SAT gene expression, surprisingly, these predictors explained only little variance for all other investigated adipokines.

CT-Quantified Adipose Tissue Distribution: Risk or Protective Factor for Complications after Rectal Cancer Surgery?

PURPOSE

Obesity is associated with increased incidence and mortality in rectal cancer (RC). However, an obesity paradox in the sense of a protective effect of obesity is discussed controversially. We evaluated whether adipose tissue distribution has an impact on medical (MC) and surgical complications (SC) after RC surgery.

METHODS

A total of 296 RC patients underwent oncological surgery and multidetector CT with quantification of total (TAT), visceral (VAT), and subcutaneous adipose tissue (SAT). Logistic regressions on SC (anastomotic leakage [n = 26], wound infection [n = 58], bleeding [n = 12], abscess [n = 32], bladder dysfunction [n = 24], burst abdomen [n = 10]), and MC (pulmonary [n = 22], cardiac [n = 18], urinary tract infection [n = 9], sepsis [n = 5]) were performed.

RESULTS

High pelvicVAT was associated with reduced risk for overall SC (OR = 0.915, p = 0.012) and anastomotic leakage (OR = 0.587, p = 0.024, CI: 0.369/0.934). In contrast, CT-quantified obesity was associated with increased risk for wound infection, bladder dysfunction, burst abdomen, overall MC, and cardiac complications (ORs up to 1.423). BMI was not associated with any SC or MC.

CONCLUSION

An obesity paradox with a protective effect of CT-quantified adipose tissue was confirmed for anastomotic leakage and overall SC. In contrast, high adipose tissue was associated with higher risk for other SC and MC. These results show a more complex influence of body composition on MC and SC. CT-quantified obesity is able to provide deeper insights to explain the obesity paradox beyond BMI.

Meta-analysis of genome-wide association studies for body fat distribution in 694 649 individuals of European ancestry

More than one in three adults worldwide is either overweight or obese. Epidemiological studies indicate that the location and distribution of excess fat, rather than general adiposity, are more informative for predicting risk of obesity sequelae, including cardiometabolic disease and cancer. We performed a genome-wide association study meta-analysis of body fat distribution, measured by waist-to-hip ratio (WHR) adjusted for body mass index (WHRadjBMI), and identified 463 signals in 346 loci. Heritability and variant effects were generally stronger in women than men, and we found approximately one-third of all signals to be sexually dimorphic. The 5% of individuals carrying the most WHRadjBMI-increasing alleles were 1.62 times more likely than the bottom 5% to have a WHR above the thresholds used for metabolic syndrome. These data, made publicly available, will inform the biology of body fat distribution and its relationship with disease.

Measurement of mean subcutaneous fat thickness: eight standardised ultrasound sites compared to 216 randomly selected sites

Ultrasound (US) provides the most accurate technique for thickness measurements of subcutaneous adipose tissue (SAT) layers. This US method was recently standardised using eight sites to capture SAT patterning and allows distinguishing between fat and embedded fibrous structures. These eight sites chosen for fat patterning studies do not represent the mean SAT thickness measured all over the body that is necessary for determining subcutaneous fat mass. This was obtained by SAT measurements at 216 sites distributed randomly all over the body. Ten participants with BMI below 28.5kgm-2 and SAT means (from eight sites) ranging from 3 mm to 10 mm were selected. The means from eight sites overestimated the means obtained from 216 sites (i.e. 2160 US measurements in the ten participants); the calibration factor of 0.65 corrects this; standard deviation (SD) was 0.05, i.e. 8%. The SD of the calibration factor transforms linearly when estimating the error range of the whole body's SAT volume (body surface area times the calibrated mean SAT thickness). The SAT masses ranged from 3.2 to 12.4 kg in this group. The standard deviations resulting from solely the calibration factor uncertainty were ±0.3 and ±1.0 kg, respectively. For these examples, the SAT percentages were 4.9(±0.4)% and 13.3(±1.0)%.

A Prospective Investigation of Body Size, Body Fat Composition and Colorectal Cancer Risk in the UK Biobank

Obesity has been consistently associated with a greater colorectal cancer risk, but this relationship is weaker among women. In the UK Biobank, we investigated the associations between body size (body mass index [BMI], height, waist circumference, and waist-to-hip ratio) and body fat composition (total body fat percentage and trunk fat percentage) measurements with colorectal cancer risk among 472,526 men and women followed for 5.6 years on average. Multivariable hazard ratios (HRs) and 95% confidence intervals (95%CI) for developing colorectal cancer (2,636 incident cases) were estimated using Cox proportional hazards models. Among men, when the highest and lowest fifths were compared, BMI (HR = 1.35, 95%CI: 1.13-1.61; Ptrend < 0.0001), waist circumference (HR = 1.66, 95%CI: 1.39-1.99; Ptrend < 0.0001), waist-to-hip ratio (HR = 1.58, 95%CI: 1.31-1.91; Ptrend < 0.0001), total body fat percentage (HR = 1.27, 95%CI: 1.06-1.53; Ptrend = 0.002), and trunk fat percentage (HR = 1.31, 95%CI: 1.09-1.58; Ptrend = 0.002) were associated with greater colorectal cancer risk. For women, only waist-to-hip ratio (HR for highest versus lowest fifth = 1.33, 95%CI: 1.08-1.65; Ptrend = 0.005) was positively associated with colorectal cancer risk. Greater body size (overall and abdominal adiposity) was positively associated with colorectal cancer development in men. For women, abdominal adiposity, rather than overall body size, was associated with a greater colorectal cancer risk.

CT-Derived Body Fat Distribution and Incident Cardiovascular Disease: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Visceral fat has been shown to be associated with increased cardiometabolic risk, but the role of subcutaneous fat remains unclear, and evidence from diverse populations is lacking. We hypothesized that visceral fat, but not subcutaneous fat, would be independently associated with incident cardiovascular disease (CVD) and all-cause mortality.

METHODS

Among 1910 participants from the Multi-Ethnic Study of Atherosclerosis with abdominal fat measurements from computed tomography scans and followed for an average of 9.3 years, we used multivariable Cox proportional hazards models to investigate the relationship of both visceral and subcutaneous fat tertiles with CVD and all-cause mortality. We tested for interaction and performed sensitivity analysis for subgroups and missing values of visceral fat.

RESULTS

Participants had mean age of 65 years, visceral fat 150 cm2, subcutaneous fat 263 cm2, and 50% were female, 21% African American, 13% Asian, and 26% Hispanic. In models adjusted for age, sex, race/ethnicity, income, education, smoking, and subcutaneous fat, there was a statistically significant positive association between visceral fat and CVD, but not mortality. The association for combined CVD may be driven by incident coronary heart disease [tertile 2: hazard ratio, 2.43 (1.38 to 4.28); tertile 3: hazard ratio, 3.00 (1.66 to 5.43)]. Additionally, we found no substantial associations between subcutaneous fat and CVD or mortality. There were no statistically significant interactions by age, sex, or race/ethnicity.

CONCLUSIONS

Visceral fat, but not subcutaneous fat, is significantly associated with increased risk for CVD in a multiethnic cohort. These data support the need for effective strategies for lifestyle changes that prevent and reduce visceral fat.

Correlation of ankle-brachial index and peripheral artery disease with the status of body fat deposition and metabolic syndrome in asymptomatic premenopausal women

INTRODUCTION

Asymptomatic peripheral artery disease (PAD) in symptom-free subjects, and people with the metabolic syndrome (MetS) is a significant correlate of cardiovascular morbidity and mortality. However, little is known about their relationship and whether this is mediated through central obesity as one of the defining components of the MetS.

MATERIALS AND METHODS

In a cross-sectional setting, 150 asymptomatic healthy premenopausal women without previously diagnosed hypertension, diabetes or known history cardiovascular diseases were consecutively enrolled. Ankle-brachial index (ABI), various parameters of general and central body fat distribution, and MetS were assessed.

RESULTS

The prevalence rates for asymptomatic PAD and MetS within the study population were calculated at 6% and 44%, respectively. Following the rigorous adjustment made by the components of MetS and clincial variables of age and serum low-density lipoprotein cholesterols (LDL-C), several indicators of general and central body fat distribution, including total, truncal and visceral body fats were found to have significantly positive correlations with log-ABI values. Moreover, log-ABI was significantly and negatively associated with the presence of MetS in both crude and multivariate models of logistic regression analysis, as adjusted by age, LDL-C and several indices of general and central fat deposition (OR [95% CI]: 0.016 [0.001 to 0.424], P value=0.013 in the multivariate adjusted model).

CONCLUSION

ABI had positive and negative associations with central obesity and MetS, respectively. Our findings strongly suggest the inverse correlation between ABI and the MetS is likely not mediated through central obesity as one the key components of MetS.

Perirenal fat thickness measured with computed tomography is a reliable estimate of perirenal fat mass

Deposition of perirenal adipose tissue has been associated with adverse renal and cardiovascular events. We compared various methods to measure perirenal adipose tissue using computerized tomography (CT)-scan and performed correlations with anthropometric measures associated with renal and cardiovascular events. Voluntary overweight and obese subjects undergoing a CT-scan for diagnostic purposes were included in the study. Perirenal adipose tissue volume, adipose tissue area of the renal sinus and perirenal fat thickness were manually measured bilaterally. The intra- and inter-observer coefficient correlations and the correlation between the diverse measures of renal adipose tissue, subcutaneous (SC-)fat and anthropometrics measures were analyzed using Pearson's correlation tests. The forty included patients (24 men, 16 women) had a mean age of 57.6 ± 18.1 years and a mean body mass index of 28.9 ± 2.9 kg/m². Despite comparable waist circumference, women had a greater SC-fat thickness compared to men, and therefore a smaller amount of visceral fat, as well as smaller perirenal fat volumes. Perirenal fat thickness was better correlated with perirenal fat volume than adipose area of the renal sinus (p <0.02). The adipose area of the renal sinus did not correlate with any anthropometric measures. In women, perirenal fat volume and thickness showed a negative correlation with SC-fat thickness and no correlation with waist circumference. In men, perirenal fat volume and thickness showed a positive correlation with waist circumference and no correlation with subcutaneous fat thickness. In conclusion, perirenal fat thickness measured with CT-scan at the level of the renal veins is a simple and reliable estimate of perirenal fat volume, that correlated negatively with SC-fat in women and positively with waist circumference in men. The adipose area of the renal sinus did not correlate with any anthropometric measure.

Assessment of fat and lean mass by quantitative magnetic resonance: a future technology of body composition research?

PURPOSE OF REVIEW

For the assessment of energy balance or monitoring of therapeutic interventions, there is a need for noninvasive and highly precise methods of body composition analysis that are able to accurately measure small changes in fat and fat-free mass (FFM).

RECENT FINDINGS

The use of quantitative magnetic resonance (QMR) for measurement of body composition has long been established in animal studies. There are, however, only a few human studies that examine the validity of this method. These studies have consistently shown a high precision of QMR and only a small underestimation of fat mass by QMR when compared with a 4-compartment model as a reference. An underestimation of fat mass by QMR is also supported by the comparison between measured energy balance (as a difference between energy intake and energy expenditure) and energy balance predicted from changes in fat mass and FFM. Fewer calories were lost and gained as fat mass compared with the value expected from measured energy balance.

SUMMARY

Current evidence in healthy humans has shown that QMR is a valid and precise method for noninvasive measurement of body composition. Contrary to standard reference methods, such as densitometry and dual X-ray absorptiometry, QMR results are independent of FFM hydration. However, despite a high accuracy and a low minimal detectable change, underestimation of fat mass by QMR is possible and limits the use of this method for quantification of energy balance.

Abdominal obesity and metabolic syndrome burden in adolescents--Penn State Children Cohort study

To investigate the association between abdominal obesity and metabolic syndrome (MetS) burden in a population-based sample of adolescents, we used data from 421 adolescents who completed the follow-up examination in the Penn State Children Cohort study. Dual-energy x-ray absorptiometry (DXA) was used to assess abdominal obesity, as measured by android/gynoid fat ratio (A/G ratio), android/whole body fat proportion (A/W proportion), visceral (VAT) and subcutaneous fat (SAT) areas. Continuous metabolic syndrome score (cMetS), calculated as the sum of the age and sex-adjusted standardized residual (Z-score) of five established MetS components, was used to assess the MetS burden. Linear regression models were used to analyze the impact of DXA measures on cMetS components. All models were adjusted for age, race, sex, and general obesity. We found abdominal obesity is significantly associated with increased cMetS. With 1 standard deviation (SD) increase in A/G ratio, A/W proportion, VAT area, and SAT area, cMetS increased by 1.34 (SE=0.17), 1.25 (SE=0.19), 1.67 (SE=0.17), and 1.84 (SE=0.20) units, respectively. At individual component level, strongest association was observed between abdominal obesity and insulin resistance (IR) than lipid-based or blood pressure-based components. VAT and SAT had a stronger impact on IR than android ratio-based DXA measurements. In conclusion, abdominal obesity is associated with higher MetS burden in adolescent population. The association between abdominal obesity and IR measure is the strongest, suggesting the key impact of abdominal obesity on IR in adolescents MetS burden.

Associations of fat mass and fat distribution with bone mineral density in Chinese obese population

The purpose of the study was to investigate the associations of fat mass (FM) and fat distribution with bone mineral density (BMD) in Chinese obese population. Three hundred and forty-seven Chinese obese females and 339 males aged 20-39 years were analyzed. Lean mass (LM), FM, percent body fat (%BF), android FM, gynoid FM, and total and regional BMD were measured using dual-energy X-ray absorptiometry. Fat distribution was assessed by android-to-gynoid FM ratio (AOI). As a result, increased central body fat had an inverse association with total and leg BMD in females but not in males. Increased FM and %BF were positively associated with arm, trunk, and pelvic BMD in Chinese obese females. Increased FM was positively associated with total, rib, and trunk BMD in Chinese obese males. The results remained almost unchanged after adjusting for LM, and LM was significantly positively associated with spine BMD in female group. FM was positively associated with trunk BMD in male group after adjusting for LM. AOI was inversely associated with total and leg BMD, and %BF was positively associated with arm, trunk, and pelvic BMD when replacing FM with %BF in female group. The results remained almost unchanged after adjusting for LM. There is no significant association in male group when replacing FM with %BF. In conclusion, our findings demonstrate that there are different associations of FM and fat distribution with BMD, and AOI has a negative association with BMD.

Physical activity and cardiorespiratory fitness as major markers of cardiovascular risk: their independent and interwoven importance to health status

The evolution from hunting and gathering to agriculture, followed by industrialization, has had a profound effect on human physical activity (PA) patterns. Current PA patterns are undoubtedly the lowest they have been in human history, with particularly marked declines in recent generations, and future projections indicate further declines around the globe. Non-communicable health problems that afflict current societies are fundamentally attributable to the fact that PA patterns are markedly different than those for which humans were genetically adapted. The advent of modern statistics and epidemiological methods has made it possible to quantify the independent effects of cardiorespiratory fitness (CRF) and PA on health outcomes. Based on more than five decades of epidemiological studies, it is now widely accepted that higher PA patterns and levels of CRF are associated with better health outcomes. This review will discuss the evidence supporting the premise that PA and CRF are independent risk factors for cardiovascular disease (CVD) as well as the interplay between both PA and CRF and other CVD risk factors. A particular focus will be given to the interplay between CRF, metabolic risk and obesity.

Body fat percentage prediction using intelligent hybrid approaches

Excess of body fat often leads to obesity. Obesity is typically associated with serious medical diseases, such as cancer, heart disease, and diabetes. Accordingly, knowing the body fat is an extremely important issue since it affects everyone's health. Although there are several ways to measure the body fat percentage (BFP), the accurate methods are often associated with hassle and/or high costs. Traditional single-stage approaches may use certain body measurements or explanatory variables to predict the BFP. Diverging from existing approaches, this study proposes new intelligent hybrid approaches to obtain fewer explanatory variables, and the proposed forecasting models are able to effectively predict the BFP. The proposed hybrid models consist of multiple regression (MR), artificial neural network (ANN), multivariate adaptive regression splines (MARS), and support vector regression (SVR) techniques. The first stage of the modeling includes the use of MR and MARS to obtain fewer but more important sets of explanatory variables. In the second stage, the remaining important variables are served as inputs for the other forecasting methods. A real dataset was used to demonstrate the development of the proposed hybrid models. The prediction results revealed that the proposed hybrid schemes outperformed the typical, single-stage forecasting models.

Comparison of brown and white adipose tissue fat fractions in ob, seipin, and Fsp27 gene knockout mice by chemical shift-selective imaging and (1)H-MR spectroscopy

Brown adipose tissue (BAT) plays a key role in thermogenesis to protect the body from cold and obesity. White adipose tissue (WAT) stores excess energy in the form of triglycerides. To better understand the genetic effect on regulation of WAT and BAT, we investigated the fat fraction (FF) in two types of adipose tissues in ob/ob, human BSCL2/seipin gene knockout (SKO), Fsp27 gene knockout (Fsp27(-/-)), and wild-type (WT) mice in vivo using chemical shift selective imaging and (1)H-MR spectroscopy. We reported that the visceral fat volume in WAT was significantly larger in ob/ob mice, but visceral fat volumes were lower in SKO and Fsp27(-/-) mice compared with WT mice. BAT FF was significantly higher in ob/ob mice than the WT group and similar to that of WAT. In contrast, WAT FFs in SKO and Fsp27(-/-) mice were lower and similar to that of BAT. The adipocyte size of WAT in ob/ob mice and the BAT adipocyte size in ob/ob, SKO, and Fsp27 mice were significantly larger compared with WT mice. However, the WAT adipocyte size was significantly smaller in SKO mice than in WT mice. Positive correlations were observed between the adipocyte size and FFs of WAT and BAT. These results suggested that smaller adipocyte size correlates with lower FFs of WAT and BAT. In addition, the differences in FFs in WAT and BAT measured by MR methods in different mouse models were related to the different regulation effects of ob, seipin, or Fsp27 gene on developing WAT and BAT.

Physical strength in boys with different levels of fat accumulation and BMI: report on South Korean junior high school boys

The figpurpose of this study was to investigate the evaluation of differences in morphological qualities in physical strength of South Korean junior high school boys. The subjects were 201 first-year junior high school boys (13.6 +/- 0.3 years, 59.0 +/- 12.8 kg, 163.1 +/- 7.4 cm, in whom height, weight, BMI, fat mass, body fat percentage and soft lean mass were measured. Items of physical strength measured were the sit and reach, 20-m shuttle run, push-ups, and sit-ups. Morphological quality was judged from two aspects, a BMI evaluation of obesity or leanness and an evaluation of the level of fat accumulation derived from regression polynomials of body fat percentage against BMI. The subjects were classified into 9 groups according to differences in morphological quality. Of the physical measurement items, boys with underdevelopment of fat in the BMI slim and normal groups showed superior results in the 20-m shuttle run, push-ups and sit-ups. In contrast, boys with overdevelopment of fat in the BMI fatty group showed significantly poorer results in these items. Meanwhile, boys with underdevelopment of fat in the BMI fatty group showed a level comparable to boys in the BMI normal and excessive fat groups in the 20-m shuttle run; boys with normal and excessive fat in the BMI normal group and boys with excessive fat in the BMI slim group in push-ups; and boys with underdevelopment of fat in the BMI slim group in sit-ups. Performance in these measurements was evaluated in detail for boys with different morphological qualities, and multiple considerations from the two aspects of physique and physical composition may be necessary to evaluate the physical strength of students in each grade.

[Screen value of anthropometric indices for hyperglycemia]

OBJECTIVE

The study was to examine whether waist-to-thigh ratio (WTR) performed better than waist-to-height ratio (WHtR), waist-to-hip ratio (WHR), waist circumference (WC), or body mass index (BMI) in relation to hyperglycemia (fasting plasma glucose > or = 5.6 mmol/L) among government employee.

METHODS

A cluster sampling was conducted in Beijing ShiJitan Hospital in August 2010. 1280 government employee were examined on height, weight, WC, hip circumference, thigh circumference, fasting glucose and so on.

RESULTS

(1) The rate of hyperglycemia was 40.16%, increasing along with age. The level of WC, BMI, WHtR, WHR, WTR, SBP, DBP, AST, TC, TG, CRE, UA in hyperglycemia group was significantly higher than that of normal glucose group (P < 0. 001), but the level of HDL-C is lower than normal glucose group. Meanwhile, the prevalence rate of fat liver in hyperglycemia group was significantly higher than that of normal glucose group. (2) Receiver operating characteristic (ROC) curve analysis was used to measure the predictive hyperglycemia performance of each anthropometric measurement based on the area under the curve (AUC). AUC of WTR (0.716) was larger than that of WHtR (0.690) (P < 0.001), WHR (0.682) (P < 0.001), WC (0.682) (P < 0.001), and BMI (0.665) (P < 0.001) for hyperglycemia. In men, AUC of WTR (0.648) was larger than that of WHtR (0.611) (P < 0.001), WHR (0.614) (P < 0.001), WC (0.598) (P < 0.001), and BMI (0.587) (P < 0.001) for hyperglycemia. In women, the AUC of WTR (0.758) was smaller than that of WHtR (0.774) (P < 0.001), and WC (0.761) (P < 0.001), but larger than that of BMI (0.738) (P < 0.001) and WHR (0.732) (P < 0.001) for hyperglycemia. Stratified by age, in women who age > or = 35 years, the AUC of WTR (0.725) was larger than that of WHtR (0.716) (P < 0.001), WC (0.705) (P < 0.001), WHR (0.676) (P < 0.001) and BMI (0.665) (P < 0.001). (3) After adjustment for age and gender, logistic regression analyses showed that WTR have the strongest association with hyperglycemia (OR = 1.70, 95% CI 1.37 - 2.11; per 1 SD increment).

CONCLUSION

Hyperglycemia is a serious health problem in government employee. WTR performed better than other four indices in all men and in women age > or = 35 for the association with hyperglycemia.

Subject positioning in the BOD POD® only marginally affects measurement of body volume and estimation of percent body fat in young adult men

INTRODUCTION

The aim of the study was to evaluate whether subject positioning would affect the measurement of raw body volume, thoracic gas volume, corrected body volume and the resulting percent body fat as assessed by air displacement plethysmography (ADP).

METHODS

Twenty-five young adult men (20.7±1.1 y, BMI = 22.5±1.4 kg/m(2)) were measured using the BOD POD® system using a measured thoracic gas volume sitting in a 'forward bent' position and sitting up in a straight position in random order.

RESULTS

Raw body volume was 58±124 ml (p<0.05) higher in the 'straight' position compared to the 'bent' position. The mean difference in measured thoracic gas volume (bent-straight = -71±211 ml) was not statistically significant. Corrected body volume and percent body fat in the bent position consequently were on average 86±122 ml (p<0.05) and 0.5±0.7% (p<0.05) lower than in the straight position respectively.

CONCLUSION

Although the differences reached statistical significance, absolute differences are rather small. Subject positioning should be viewed as a factor that may contribute to between-test variability and hence contribute to (in)precision in detecting small individual changes in body composition, rather than a potential source of systematic bias. It therefore may be advisable to pay attention to standardizing subject positioning when tracking small changes in PF are of interest. The cause of the differences is shown not to be related to changes in the volume of isothermal air in the lungs. It is hypothesized and calculated that the observed direction and magnitude of these differences may arise from the surface area artifact which does not take into account that a subject in the bent position exposes more skin to the air in the device therefore potentially creating a larger underestimation of the actual body volume due to the isothermal effect of air close to the skin.

Ultrasound measurement of subcutaneous adipose tissue thickness accurately predicts total and segmental body fat of young adults

This study evaluated the ability of ultrasound measurement of subcutaneous adiposity to accurately determine whole body and segmental body fat in young adults aged 18-29 years. Subcutaneous adipose tissue (SAT) thickness was measured by ultrasound at five body sites in 135 subjects (83 men, 52 women) and compared with the corresponding segmental fat mass measured by dual energy X-ray absorptiometry (DXA). Ultrasound measures of SAT thickness were strongly correlated to segmental fat mass and total percentage (%) body fat (r = 0.697-0.907, p < 0.01). Prediction equations generated using quantile regression found SAT thickness at the abdomen and thigh to accurately predict % body fat in men (standard error of the estimate, SEE = 1.9%, 95% limits of agreement (LoA); -3.6% to +3.8%) and SAT thickness at the abdomen and medial calf to accurately predict % body fat in women (SEE = 3.0%, LoA; -6.5% to +5.4%). These data indicate that ultrasound measurement of SAT thickness proportionally reflects segmental fat mass and accurately predicts % body fat in young adults.

Circulating lipocalin 2 is associated with body fat distribution at baseline but is not an independent predictor of insulin resistance: the prospective Cyprus Metabolism Study

OBJECTIVE

Lipocalin 2 (LCN2 or NGAL), a protein derived from neutrophils, macrophages, adipocytes, and other cells, has been proposed to be a link between obesity and insulin resistance (IR), but animal and cross-sectional human studies have revealed conflicting results. We studied the association of serum lipocalin 2 with anthropometric, metabolic, and cardiovascular risk markers in young healthy men cross-sectionally and, for the first time, prospectively after 2 years of follow-up, with and without adjustment for potential confounders including serum creatinine.

DESIGN

Two hundred and seventy-two participants were randomly selected from the Cyprus Metabolism Study (1056 men, 18 years), of whom 93 subjects participated in the follow-up study 2 years after baseline assessment. Associations were also explored between total and free leptin levels (to serve as positive controls) and anthropometric metabolic variables.

RESULTS

In the cross-sectional study, lipocalin 2 levels were marginally correlated in the unadjusted model with central fat distribution but not with body weight or total body fat mass. After adjusting for age, smoking, activity, body mass index, fat percentage, waist-to-hip ratio, and serum creatinine, no correlation was found with any cardiovascular risk factor. There was no correlation with the homeostasis model assessment of IR (HOMA-IR) at baseline. In the prospective analyses, baseline levels of lipocalin 2 were not predictive of any variables in unadjusted or adjusted models. As expected, total and free leptin were associated with anthropometric and metabolic variables both cross-sectionally and prospectively.

CONCLUSIONS

We demonstrate that lipocalin 2 is not an independent predictor of metabolic and cardiovascular risk factors in young men cross-sectionally or prospectively.

[Somatotypological characteristics of the development of fat component in students]

Individual typological characteristics were studied in first- and fourth-year female students. It was shown that the dominant somatotype was micromesomatic in the first-year students and macrosomal in the senior students. Body component composition was studied in the examinees. No significant average group differences were found in the absolute and relative body fat content in the students. The somatotype distribution using the weight-height ratio indicated significant differences in fat components in the female representatives of different types of constitution.

Quantification of human body fat tissue percentage by MRI

The MRI-based evaluation of the quantity and regional distribution of adipose tissue is one objective measure in the investigation of obesity. The aim of this article was to report a comprehensive and automatic analytical method for the determination of the volumes of subcutaneous fat tissue (SFT) and visceral fat tissue (VFT) in either the whole human body or selected slices or regions of interest. Using an MRI protocol in an examination position that was convenient for volunteers and patients with severe diseases, 22 healthy subjects were examined. The software platform was able to merge MRI scans of several body regions acquired in separate acquisitions. Through a cascade of image processing steps, SFT and VFT volumes were calculated. Whole-body SFT and VFT distributions, as well as fat distributions of defined body slices, were analysed in detail. Complete three-dimensional datasets were analysed in a reproducible manner with as few operator-dependent interventions as possible. In order to determine the SFT volume, the ARTIS (Adapted Rendering for Tissue Intensity Segmentation) algorithm was introduced. The advantage of the ARTIS algorithm was the delineation of SFT volumes in regions in which standard region grow techniques fail. Using the ARTIS algorithm, an automatic SFT volume detection was feasible. MRI data analysis was able to determine SFT and VFT volume percentages using new analytical strategies. With the techniques described, it was possible to detect changes in SFT and VFT percentages of the whole body and selected regions. The techniques presented in this study are likely to be of use in obesity-related investigations, as well as in the examination of longitudinal changes in weight during various medical conditions.

Measuring abdominal adipose tissue: comparison of simpler methods with MRI

OBJECTIVE

This cross-sectional study compares the relationship of visceral and total abdominal adipose tissue (VAT and TAAT) measurements obtained with magnetic resonance imaging (MRI) and a range of 'simpler' techniques suitable for field or bedside use: BMI, waist circumference (WC), bioelectrical impedance (BIA) devices and dual X-ray absorptiometry (DXA).

METHOD

120 participants were recruited, stratified by gender and BMI (20 men and 20 women within each group: lean, overweight and obese). Measurements included height, weight, WC (at midpoint), DXA L2-L4 fat, and BIA (two whole-body and one abdominal device). MRI was used as the reference.

RESULTS

MRI data showed that men have more VAT than women, (mean 147 vs. 93 cm(2)) despite less TAAT (362 vs. 405 cm(2)). Correlations of simpler abdominal fat measures showed significantly higher correlations with TAAT than with VAT in men and women. Similarly, trunk and whole-body fat measures were significantly more strongly correlated with TAAT than with VAT.

CONCLUSION

None of the simpler techniques show strong correlations with VAT measured by MRI, but WC, abdominal BIA 'visceral fat level' and DXA L2-L4 fat all show similar and strong correlations with TAAT and may be useful in large scale surveys.

[Validity of body fat estimation by near infrared spectroscopy in long-term care elderly patients: a comparison with skinfold thickness]

AIM

The aim of this study was to examine the validity of body fat measurement by near infrared spectroscopy (NIRS) in long-term care elderly patients.

METHODS

The subjects were 59 elderly patients (23 men, 36 women, age 82.0+/-6.6 years) and 38 healthy young persons (19 men, 19 women, age 28.1+/-6.1 years). Percentage of body fat (%BF), body fat mass (BFM), and lean body mass (LBM) were estimated by NIRS and skinfold thickness (SF). Body fat was compared by genders and between the elderly patients and the healthy young subjects. The relationship between NIRS and SF of the elderly patients was compared with that of the healthy young subjects.

RESULTS

Means of body fat variables of the elderly patients by NIRS were: %BF 18.6%, BFM 8.8 kg, LBM 37.7 kg for men; and %BF 26.0%, BFM 10.7 kg LBM, 29.6 kg; for women. The %BF and BFM values estimated by NIRS were significantly greater than the respective values measured by SF; LBM estimated by NIRS was significantly less than that by SF. These results show that body fat measured by SF may be undervalued. The correlation between NIRS and SF was significant (r > or =0.49, p < or =0.05), and the regression lines for the elderly patients and the healthy young were not significantly different. Body fat of elderly patients by NIRS may be similar to that of healthy young by SF.

CONCLUSIONS

The results suggest that NIRS yields higher values than SF in measurement of body fat in long-term care elderly patients.

Extent of emphysema on HRCT affects loss of fat-free mass and fat mass in COPD

BACKGROUND

Although muscle loss is thought to be a prognostic factor in chronic obstructive pulmonary disease (COPD), its determinants remain unclear.

AIM

To verify the hypothesis that fat-free mass (FFM) and fat mass (FM) are associated with the extent of emphysema in COPD patients.

PATIENTS AND METHODS

A total of 112 stable, male current or ex-smokers with or without COPD attending a secondary care specialist COPD clinic were studied. FFM and FM were measured by bioelectrical impedance analysis. We also assessed the nutrition status, muscle strength by the handgrip test, exercise tolerance by the 6-minute walking test, airflow limitation and diffusion capacity, the extent of emphysema by high-resolution CT scan, systemic inflammation status using C-reactive protein, and a lipid-related hormone (adiponectin).

RESULTS

The FFM index (FFMI), which was defined as the FFM divided by the square of the body height, was significantly correlated with age, the total number of lymphocytes, handgrip strength, distance on 6-minute walking, airflow limitation, diffusion capacity, extent of emphysema, and C-reactive protein. On multivariate analysis, the FFMI was associated with handgrip strength and inversely correlated with the extent of emphysema. The FM index (FMI) was positively correlated with pack-years, and was inversely correlated with the extent of emphysema and concentrations of adiponectin.

CONCLUSION

The extent of emphysema was correlated with skeletal muscle loss and also the FM.

Waist to height ratio is a simple and effective obesity screening tool for cardiovascular risk factors: Analysis of data from the British National Diet And Nutrition Survey of adults aged 19-64 years

OBJECTIVE AND METHOD

To analyse data from the nationally representative National Diet and Nutrition Survey (NDNS) collected in 2000/2001 and to investigate how the BMI and two proxy indicators of central fat distribution, namely the waist circumference and the waist to height ratio (WHtR), are associated with each other and with cardiovascular disease (CVD) risk factors.

RESULTS

Screening health risk by BMI alone would 'miss' 35% of men and 14% of women who are within the normal BMI range (18.5-25 kg/m(2)) but have central fat distribution, defined by WHtR > 0.5. In the total population this equates to 17% of all men and 6% of all women who would be inadequately screened by BMI alone. Compared to BMI, WHtR was more closely associated with CVD risk factors among both men and women. Furthermore, in a combined analysis of men and women, central fat distribution with a normal BMI was associated with higher levels of CVD risk factors than being overweight without central fat distribution.

CONCLUSION

WHtR is a simple and effective, non-invasive screening tool for CVD risk factors. Our proposed boundary value of 0.5 translates into a simple public health message: 'Keep your waist circumference to less than half your height'.

Plasma pigment epithelium-derived factor is positively associated with obesity in Caucasian subjects, in particular with the visceral fat depot

OBJECTIVE

Adipose tissue releases factors (adipokines) that influence local, peripheral as well as central processes. In the present study, we determined the relationship between plasma concentration of a recently identified adipokine, pigment epithelium-derived factor (SERPINF1), and human obesity, particularly specific adipose tissue depots, and other features of the metabolic syndrome.

METHODS

We examined the plasma concentration of SERPINF1, anthropometric parameters, abdominal s.c. and visceral adipose tissue, lipid, glucose, insulin, and alanine aminotransferase level in a non-diabetic general Caucasian population (n=59).

RESULTS

Plasma SERPINF1 level in males (6.2+/-2.1 microg/ml) was higher than in females (3.1+/-1.4 microg/ml; P<0.001). Plasma SERPINF1 was positively correlated with age and all features of metabolic syndrome. However, in multiple linear regression analysis with adjustment for age and gender, only visceral fat thickness (beta=0.361, P=0.010) and body mass index (beta=0.288, P=0.008) were significant independent determinants of plasma SERPINF1 level, together with gender (beta=-0.424, P<0.001).

CONCLUSIONS

We conclude that the plasma SERPINF1 level is strongly associated with body adiposity, in particular with the visceral fat depot in the non-diabetic general population. This association may (partly) explain the relationship between SERPINF1 and metabolic syndrome in this population.

Gender dimorphism in body composition abnormalities in acromegaly: males are more affected than females

BACKGROUND

Acromegaly changes body composition (BC), but long-term gender differences have not been reported.

OBJECTIVE

To evaluate BC in active and controlled acromegalic patients.

DESIGN AND METHODS

Clinical and biochemical variables and BC (by dual-energy X-ray absorptiometry) were evaluated in 60 acromegalic patients (19 active, 41 controlled) and 105 controls, matched for age and gender.

RESULTS

Acromegalic males (n=24) had more total mass (89+/-13 vs 76.5+/-15.3 kg, P<0.001), lean body mass (LBM; 64.6+/-8.7 vs 56.4+/-5.8 kg, P<0.001), and bone mineral content (BMC; 2.9+/-0.5 vs 2.6+/-0.3 kg, P<0.05) than controls (n=33). Controlled male patients (n=14) had more total mass (89+/-14.7 vs 76.5+/-15.3 kg, P<0.05) and a trend to have more LBM (61.8+/-9.4 vs 56.4+/-5.8 kg, P=0.065) than controls. Only in active disease was a decrease in fat mass (FM) observed, compared with controlled patients and controls (males: 19.5+/-5.3 vs 27+/-6.2 and 25.9+/-4%, P<0.001; females: 30.3+/-6.7 vs 37.1+/-5.8 and 36.5+/-6.6%, P<0.01). In females, no further differences were observed. No differences in BMC were found between eugonadal and hypogonadal acromegalic patients, but in hypogonadal females, acromegaly appeared to prevent the BMC loss seen in hypogonadal postmenopausal controls. GH and IGF1 levels were negatively correlated with FM (males, P<0.05; females, P<0.001), but in the regression analysis GH was a predictor of FM only in women.

CONCLUSIONS

Control of acromegaly reverts decreased FM in both genders; only in males more total mass and a trend for more LBM persist. The anabolic effect of GH on bone reverted in cured males, but persisted in females and appeared to override the bone loss of menopause.

Assessment of body composition in Sri Lankan children: validation of a bioelectrical impedance prediction equation

OBJECTIVE

To develop bioelectrical impedance analysis (BIA) equations to predict total body water (TBW) and fat-free mass (FFM) of Sri Lankan children.

SUBJECTS/METHODS

Data were collected from 5- to 15-year-old healthy children. They were randomly assigned to validation (M/F: 105/83) and cross-validation (M/F: 53/41) groups. Height, weight and BIA were measured. TBW was assessed using isotope dilution method (D(2)O). Multiple regression analysis was used to develop preliminary equations and cross-validated on an independent group. Final prediction equation was constructed combining the two groups and validated by PRESS (prediction of sum of squares) statistics. Impedance index (height(2)/impedance; cm(2)/Omega), weight and sex code (male=1; female=0) were used as variables.

RESULTS

Independent variables of the final prediction equation for TBW were able to predict 86.3% of variance with root means-squared error (RMSE) of 2.1 l. PRESS statistics was 2.1 l with press residuals of 1.2 l. Independent variables were able to predict 86.9% of variance of FFM with RMSE of 2.7 kg. PRESS statistics was 2.8 kg with press residuals of 1.4 kg. Bland Altman technique showed that the majority of the residuals were within mean bias+/-1.96 s.d.

CONCLUSIONS

Results of this study provide BIA equation for the prediction of TBW and FFM in Sri Lankan children. To the best of our knowledge there are no published BIA prediction equations validated on South Asian populations. Results of this study need to be affirmed by more studies on other closely related populations by using multi-component body composition assessment.

Good Fat, Bad Fat–Does Location Matter?

A technique that allows rapid noninvasive imaging of abdominal fat without the potentially harmful effects of ionizing radiation would be useful in diagnosing overweight and obese children and in developing effective strategies for weight management. Siegel et al describe a quick, safe, and reproducible single-section MR method for quantifying subcutaneous and visceral abdominal fat and its distribution in preadolescents and adolescents. Although larger studies are needed, their study results confirm the use of T1-weighted MR imaging at a single level for estimating adipose tissue volumes and distribution.

Birth weight categorization according to gestational age does not reflect percentage body fat in term and preterm newborns

This study was performed to prove the applicability of the small-for-gestational age (SGA), appropriate-for-gestational age (AGA), and large-for-gestational age (LGA) classification depending on birth weight to predict percentage body fat (%BF) measured by dual-energy X-ray absorptiometry (DXA) in term and preterm infants. The data of 159 healthy term and preterm neonates (87 boys and 72 girls) with a gestational age at delivery of 38.4 weeks from two longitudinal studies were analyzed. Anthropometry and body composition data were assessed within the first 10 days after birth. Correlations between anthropometric parameters and fat mass measured by DXA were calculated. Prevalences of observations with low, middle, and high %BF measured by DXA were compared between SGA, AGA, and LGA groups, according to sex and gestational age. In term infants, 42.9% of the newborns with less than 10% body fat were classified to be AGA; 9.9% of all AGA newborns had less than 10% body fat. For the whole group, among the ratios investigated, the weight-length ratio (r=0.82) showed the best correlation to fat mass measured by DXA. The %BF at the time of study was higher in girls (14.75%) than in boys (11.95%). In conclusion, traditional classification based on birth weight centiles does not reflect %BF in term and preterm newborns.

Total and intraabdominal fat distribution in preadolescents and adolescents: measurement with MR imaging

PURPOSE

To prospectively correlate single- and multisection magnetic resonance (MR) imaging measurements with clinical measurements for assessment of abdominal adipose tissue volumes in healthy (control subjects), overweight, and diabetic overweight preadolescents and adolescents.

MATERIALS AND METHODS

The study was approved by the institutional internal review board and was HIPAA compliant. Informed consent was obtained from parents, and assent was obtained from control subjects and patients. Thirty total study subjects (20 male, 10 female; age range, 10-18 years; mean, 14.5 years) underwent MR imaging, anthropometric measurement, and dual x-ray absorptiometry (DXA). A computer-assisted software program was used to quantify subcutaneous, visceral, and total abdominal adipose tissue volumes. Single-section measurements at disk space L4-L5 and whole-abdominal multisection measurements were compared, and each method was tested for correlations with anthropometric and DXA measurements with Spearman rho and Pearson correlation (r) coefficients. Single- and multisection image analyses required 5 and 25 minutes per subject, respectively.

RESULTS

There was a high degree of correlation between single- and multisection MR imaging methods for measurement of subcutaneous (r = 0.97), visceral (r = 0.96), and total abdominal fat (r = 0.97). MR imaging fat measurements strongly correlated with anthropometric measurements (rho correlation range, 0.81-0.96; P <or= .02), with overlapping 95% confidence intervals (CIs) for single- and multisection MR imaging correlations. MR imaging percentage of intraabdominal fat measurements (mean, 23%; 95% CI: 17%, 29%) highly correlated with DXA abdominal fat measurements (mean, 26%; 95% CI: 21%, 31%). Significant differences were found among healthy subjects, overweight patients, and diabetic overweight patients for total fat volumes (P < .001) but not for fat distribution patterns.

CONCLUSION

Single- and multisection MR imaging measurements for the quantitative assessment of abdominal adipose tissue strongly correlate with clinical and DXA fat measurements.

Automated quantification of body fat distribution on volumetric computed tomography

OBJECTIVE

To develop a computerized method to automatically quantify visceral and subcutaneous fat distribution within the abdomen and pelvis on volumetric computed tomographic (CT) images.

METHODS

Given the slices of interest, the algorithm automatically delineates a contour that separates the visceral fat from the subcutaneous fat on each slice. Explicitly, starting with extraction of the body perimeter, radii at a fixed angle increment are drawn from the perimeter to the center of the body. Along each radius, intensity profile is analyzed to determine the point on the subcutaneous fat layer that is closest to the body center (inner point). All inner points are then connected to form an inner contour, and a specific smoothing algorithm is subsequently applied to correct suboptimal results. Pixels having HU values between -190 and -30 are considered fat pixels. This procedure is repeated on each of the slices of interest. The visceral and subcutaneous fat volumes computed automatically were compared with those after the radiologist's adjustments. Ratios of volumetric visceral fat-to-total fat and visceral fat-to-subcutaneous fat were compared on average and with single-slice measurements obtained at L4 and L5 vertebral body levels.

RESULTS

Subcutaneous and visceral fat were automatically segmented using this algorithm on 419 axial CT slices in 9 CT scans (patients) within the abdomen and pelvis. The overall average percentage difference between the automated segmentation and the segmentation edited by the radiologist were 1.54% for the visceral fat and 0.65% for the subcutaneous fat.

CONCLUSIONS

Preliminary results have shown that total compartmental fat, including visceral and subcutaneous fat, can be automatically and accurately segmented on volumetric CT.

New imaging techniques of fat, muscle and liver within the context of determining insulin sensitivity

Body fat distribution and ectopic fat deposition are important determinants of insulin sensitivity. Fat deposition in muscle and the liver, in particular, has been found to impair insulin signalling in these insulin-sensitive tissues. Thus, exact quantification of fat content may help to distinguish between different sites of insulin resistance. Increased fat deposition in the visceral compartment compared with the subcutaneous depot also represents an important factor leading to insulin resistance. Recent data clearly showed that visceral fat is a strong determinant of liver fat content. Exact quantification of fat distribution by magnetic resonance imaging and magnetic resonance spectroscopy may help to define distinct 'fat-distribution phenotypes'. This may allow a search for new candidate genes for type 2 diabetes mellitus and identify, at an early stage, individuals at risk for decline in insulin sensitivity.

Anthropometry and body composition do not predict bioavailable androgen or progesterone concentration in adolescent girls

Our objective was to test the hypothesis that anthropometry and body composition were independently associated with sex-steroid concentration in adolescent girls. Premenarcheal (age, mean +/- SD = 10.9 +/- 0.6, N = 51), perimenarcheal (age = 13.7 +/- 0.6, N = 74), and postmenarcheal (age = 16.7 +/- 0.6, N = 44) cohorts provided saliva at morning recess during the schoolday over 6 weeks. Estradiol, testosterone, progesterone, and dehydroepiandrosterone (DHEA) were quantified. Age, developmental cohort, self-reported Tanner stage of breast development and pubic-hair distribution, gynecological age, height, weight, waist/hip ratio, and percent body fat (by impedance) were assessed. Repeated measures were reduced to a mean. Data were hierarchically standardized for sexual maturation status, and then used to predict anthropometry/percent body fat. After intensive repeated sampling, individuals still varied widely in testosterone, progesterone, and DHEA concentrations within a developmental cohort (35.0 < or = coefficient of variation < or = 66.5%). Individual hormone concentration was repeatable across 2 years (0.51 < or = r(2) < or = 0.73). In spite of the variability within a cohort, there was no evidence for an association between the standardized hormone and body mass index, percent body fat, or waist/hip ratio, whether or not measures were age-adjusted (21 univariate tests; 0.19 < or = P < or = 0.96). Stratification by developmental cohort also did not reveal associations. Low estradiol assay precision precluded analyses. In conclusion, despite considerable population variation in hormone concentration after repeated sampling, no evidence supported an association between anthropometry or pecent body fat and testosterone, progesterone, or DHEA in adolescent girls.

Evaluation of body composition methods for accuracy

The objective of this study was to evaluate the accuracy of a variety of portable methods and instruments used to estimate body composition or percentage body fat (%BF) in a systematic, comprehensive manner on a wide range of subjects. The %BF was estimated using four skinfold protocols, three girth measurement protocols, two bioelectric impedance analysis (BIA) instruments, and one near-infrared instrument on 121 subjects. The subjects ranged in age from 21 to 51 years; weight ranged from 105 to 226 pounds and %BF from 8.3% to 38.3%; and the group was 29% male. The %BF estimates were compared to the values obtained from the generally accepted reference standard, underwater weighing (UWW). The correlation coefficients (r) between the test methods and UWW ranged from 0.48 to 0.72. Regression analysis resulted in a range of slopes from 0.48 to 0.93, y-intercept range from 3.8 to 13.1, and standard error of the estimate range from 3.8 to 7.5. All of the methods tended to overestimate lower and underestimate higher %BF. With two exceptions, all methods appeared more accurate for males than females. In general, the near-infrared appeared least and BLA appeared most accurate. In conclusion, in our opinion, most of the methods were not sufficiently accurate to use on a wide range of individuals. Although they may be sufficiently accurate on the narrow sample of subjects on which they were developed, they may not be as accurate for the general population.

Comparison of CT and dual-energy DEXA using a modified trunk compartment in the measurement of abdominal fat

The quantification of abdominal fat is a marker of health risk. While dual-energy x-ray absorptiometry (DEXA) is easily applied, it measures overall fat, although abdominal fat may be a better indicator of health risk from obesity. We have evaluated whether a subcomponent of DEXA measurements correlates better with computed tomography (CT) for body fat than those traditionally used. Forty-seven healthy adults (22 M/25 F), aged 54.5+/-15.8 yr (mean+/-SD), with BMI of 27.1+/-4.6 kg/m2 participated in a cross-sectional study. Body fat was measured using abdominal CT and DEXA for total fat, trunk fat, and a modified trunk measurement that excludes the chest, termed "lower trunk," and compared. The coefficient of variation for DEXA measurements for trunk, lower trunk, and total body were 1.98, 3.12, and 0.85%, respectively. Mean DEXA for percentage fat ranged from 31.7% to 34.1% for trunk, lower trunk, and total body, compared to 54.2% for abdominal CT (p<0.003 for each pairwise comparison). Lower trunk, whole trunk, and total body DEXA measurements were not different. Measurement of subcomponents of fat content by DEXA is not superior to whole body measurements and remains consistently lower than measurements by CT.