Assessment of abdominal fat compartments using DXA in premenopausal women from anorexia nervosa to morbid obesity

Association between visceral adipose tissue area and infertility: a cross-sectional analysis

RESEARCH QUESTION

Is intra-abdominal fat obesity associated with infertility?

DESIGN

This study analysed data from the 2013-2018 National Health and Nutrition Examination Survey, with a total of 3013 women enrolled. The participants were divided into two groups: infertility and non-infertility. Differences between the two groups were analysed using a weighted Student's t-test or Mann-Whitney U-test for continuous variables, or a weighted chi-squared test for categorical data. Visceral adipose tissue area (VATA) was assessed by dual-energy X-ray absorptiometry. The independent association between infertility and log VATA was assessed by weighted multivariate logistic regression models. Subgroup analyses were performed to assess the strength of the results. Interaction tests were used to examine whether covariates interacted with log VATA to influence infertility.

RESULTS

Log VATA was significantly higher in the infertility group compared with the non-infertility group (P < 0.001). After adjustment for potential confounders, the results of multivariate logistic regression analysis revealed that an increase in log VATA was associated with increased prevalence of female infertility (OR = 2.453, 95% CI 1.278-4.792). Subgroup analyses showed this association in individuals aged <35 years (P = 0.002), Mexican-Americans (P = 0.033), non-hypertensive individuals (P = 0.013) and non-diabetic individuals (P = 0.003).

CONCLUSIONS

An enlarged VATA is associated with increased risk of infertility. The direct effect of VATA on female infertility needs to be clarified further to provide a basis for future prevention and treatment of female infertility.

PTP1B mediates the inhibitory effect of MFGE8 on insulin signaling through the β5 integrin

Integrins are cell adhesion receptors that dimerize to mediate cell-cell interactions and regulate processes, including proliferation, inflammation, and tissue repair. The role of integrins in regulating insulin signaling is incompletely understood. We have previously shown that binding of the integrin ligand milk fat globule epidermal growth factor like 8 (MFGE8) to the αvβ5 integrin promotes termination of insulin receptor signaling in mice. Upon ligation of MFGE8, integrin β5 complexes with the insulin receptor beta (IRβ) in skeletal muscle, resulting in dephosphorylation of IRβ and reduction of insulin-stimulated glucose uptake. Here, we investigate the mechanism by which the interaction between β5 and IRβ impacts IRβ phosphorylation status. We show in in vitro and in vivo in skeletal muscle in mice that antibody-mediated blockade of the β5 integrin inhibits and recombinant MFGE8 promotes PTP1B binding to and dephosphorylation of IRβ resulting in increased or reduced insulin-stimulated glucose uptake, respectively. The β5-PTP1B complex is recruited by MFGE8 to IRβ leading to termination of canonical insulin signaling. β5 blockade enhances insulin-stimulated glucose uptake in wildtype but not Ptp1b KO mice indicating that PTP1B functions downstream of MFGE8 in modulating insulin receptor signaling. Furthermore, in a human cohort, we report serum MFGE8 levels correlate with indices of insulin resistance. These data provide mechanistic insights into the role of MFGE8 and β5 in regulating insulin signaling.

MFGE8 inhibits insulin signaling through PTP1B

The role of integrins in regulating insulin signaling is incompletely understood. We have previously shown that binding of the integrin ligand milk fat globule epidermal growth factor like 8 (MFGE8) to the αvβ5 integrin promotes termination of insulin receptor signaling in mice. Upon ligation of MFGE8, β5 complexes with the insulin receptor beta (IRβ) in skeletal muscle resulting in dephosphorylation of IRβ and reduction of insulin-stimulated glucose uptake. Here we investigate the mechanism by which the interaction between β5 and IRβ impacts IRβ phosphorylation status. We show that β5 blockade inhibits and MFGE8 promotes PTP1B binding to and dephosphorylation of IRβ resulting in reduced or increased insulin-stimulated myotube glucose uptake respectively. The β5-PTP1B complex is recruited by MFGE8 to IRβ leading to termination of canonical insulin signaling. β5 blockade enhances insulin-stimulated glucose uptake in wild type but not Ptp1b KO mice indicating that PTP1B functions downstream of MFGE8 in modulating insulin receptor signaling. Furthermore, in a human cohort, we report serum MFGE8 levels correlate with indices of insulin resistance. These data provide mechanistic insights into the role of MFGE8 and β5 in regulating insulin signaling.

Visceral Adipose Tissue is Negatively Associated With Bone Mineral Density in NHANES 2011-2018

Context

The relationship of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) with bone mineral density (BMD) is not well established.

Objective

To examine the associations of VAT and SAT with total body BMD in a large, nationally representative population with a wide range of adiposity.

Methods

We analyzed 10 641 subjects aged 20 to 59 years in National Health and Nutrition Examination Survey 2011-2018 who had undergone total body BMD and had VAT and SAT measured by dual-energy X-ray absorptiometry. Linear regression models were fitted while controlling for age, sex, race or ethnicity, smoking status, height, and lean mass index.

Results

In a fully adjusted model, each higher quartile of VAT was associated with an average of 0.22 lower T-score (95% CI, -0.26 to -0.17, P < 0.001), whereas SAT had a weak association with BMD but only in men (-0.10; 95% CI, -0.17 to -0.04, P = 0.002). However, the association of SAT to BMD in men was no longer significant after controlling for bioavailable sex hormones. In subgroup analysis, we also found differences in the relationship of VAT to BMD in Black and Asian subjects, but these differences were eliminated after accounting for racial and ethnic differences in VAT norms.

Conclusions

VAT has a negative association with BMD. Further research is needed to better understand the mechanism of action and, more generally, to develop strategies for optimizing bone health in obese subjects.

Effects of a Dulaglutide plus Calorie-Restricted Diet versus a Calorie-Restricted Diet on Visceral Fat and Metabolic Profiles in Women with Polycystic Ovary Syndrome: A Randomized Controlled Trial

The effects of dulaglutide and a calorie-restricted diet (CRD) on visceral adipose tissue (VAT) and metabolic profiles in polycystic ovary syndrome (PCOS) have not been extensively investigated. In this study, we investigated whether dulaglutide combined with CRD could further reduce VAT and promote clinical benefits as compared with a CRD regimen alone in overweight or obese PCOS-affected women. Between May 2021 and May 2022, this single-center, randomized, controlled, open-label clinical trial was conducted. Overall, 243 participants with PCOS were screened, of which 68 overweight or obese individuals were randomly randomized to undergo dulaglutide combined with CRD treatment (n = 35) or CRD treatment alone (n = 33). The duration of intervention was set as the time taken to achieve a 7% weight loss goal from baseline body weight, which was restricted to 6 months. The primary endpoint was the difference in the change in VAT area reduction between the groups. The secondary endpoints contained changes in menstrual frequency, metabolic profiles, hormonal parameters, liver fat, and body composition. As compared with the CRD group, the dulaglutide + CRD group had a considerably shorter median time to achieve 7% weight loss. There was no significant between-group difference in area change of VAT reduction (-0.97 cm², 95% confidence interval from -14.36 to 12.42, p = 0.884). As compared with CRD alone, dulaglutide + CRD had significant advantages in reducing glycated hemoglobin A1c and postprandial plasma glucose levels. The results of the analyses showed different changes in menstruation frequency, additional metabolic profiles, hormonal markers, liver fat, and body composition between the two groups did not differ significantly. Nausea, vomiting, constipation, and loss of appetite were the main adverse events of dulaglutide. These results emphasize the value of dietary intervention as the first line of treatment for PCOS-affected women, while glucagon-like peptide 1 receptor agonist therapy provides an efficient and typically well tolerated adjuvant therapy to aid in reaching weight targets based on dietary therapy in the population of overweight/obese PCOS-affected women.

High-fat diet causes undesirable bone regeneration by altering the bone marrow environment in rats

OBJECTIVE

Diet structure has changed greatly over the last few decades, and high-calorie diets have become an integral part of people's daily diet, as well as the important cause of obesity in society. Several organ systems, including the skeletal system, are seriously affected by high-fat-diets (HFD) in the world. There is, however, still a lack of knowledge about the effects of HFD on bone regeneration and the possible mechanisms involved. In this study, the difference in bone regeneration between rats under HFD and low-fat-diets (LFD) was evaluated by monitoring the process of bone regeneration in distraction osteogenesis (DO) model animals, as well as the possible mechanisms.

METHODS

A total of 40 Sprague Dawley (SD) rats (5 weeks old) were randomly divided into HFD group (n=20) and LFD group (n=20). Except for feeding methods, there were no differences between the two groups in terms of treatment conditions. All animals received the DO surgery eight weeks after starting to feed. After a delay of 5 days (latency phase), the active lengthening phase was performed for 10 days (0.25 mm/12 h), and the consolidation phase followed for 42 days. An observational study of bone included radioscopy (once a week), micro-computed tomography (CT), general morphology, biomechanics, histomorphometry, and immunohistochemistry.

RESULT

The results showed that HFD group had a higher body weight than LFD group after 8, 14, and 16 weeks of feeding. Furthermore, at the final observation, there were statistically significant differences between LFD group and HFD group in terms of total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) levels. Additionally, observations on bone regeneration showed a slower regeneration and a lower biomechanical strength in HFD group than LFD group, based on radiography, micro-CT, general morphology, biomechanics, histomorphometry, and immunohistochemistry.

CONCLUSION

In this study, HFD resulted in elevated blood lipids, increased adipose differentiation at the bone marrow level, and delayed bone regeneration. The pieces of evidence are beneficial to better understand the association between diet and bone regeneration and to adjust the diet optimally for fracture patients.

MRI Based Validation of Abdominal Adipose Tissue Measurements From DXA in Postmenopausal Women

INTRODUCTION

Visceral adipose tissue (VAT) is a hypothesized driver of chronic disease. Dual-energy X-ray absorptiometry (DXA) potentially offers a lower cost and more available alternative compared to gold-standard magnetic resonance imaging (MRI) for quantification of abdominal fat sub-compartments, VAT and subcutaneous adipose tissue (SAT). We sought to validate VAT and SAT area (cm2) from historical DXA scans against MRI.

METHODOLOGY

Participants (n = 69) from the Women's Health Initiative (WHI) completed a 3 T MRI scan and a whole body DXA scan (Hologic QDR2000 or QDR4500; 2004-2005). A subset of 43 participants were scanned on both DXA devices. DXA-derived VAT and SAT at the 4th lumbar vertebrae (5 cm wide) were analyzed using APEX software (v4.0, Hologic, Inc., Marlborough, MA). MRI VAT and SAT areas for the corresponding DXA region of interest were quantified using sliceOmatic software (v5.0, Tomovision, Magog, Canada). Pearson correlations between MRI and DXA-derived VAT and SAT were computed, and a Bland-Altman analysis was performed.

RESULTS

Participants were primarily non-Hispanic white (86%) with a mean age of 70.51 ± 5.79 years and a mean BMI of 27.33 ± 5.40 kg/m2. Correlations between MRI and DXA measured VAT and SAT were 0.90 and 0.92, respectively (p ≤ 0.001). Bland-Altman plots showed that DXA-VAT slightly overestimated VAT on the QDR4500 (-3.31 cm2); this bias was greater in the smaller subset measured on the older DXA model (QDR2000; -30.71 cm2). The overestimation of DXA-SAT was large (-85.16 to -118.66 cm2), but differences were relatively uniform for the QDR4500.

CONCLUSIONS

New software applied to historic Hologic DXA scans provide estimates of VAT and SAT that are well-correlated with criterion MRI among postmenopausal women.

Subcutaneous and visceral fat assessment by DXA and MRI in older adults and children

OBJECTIVE

Given the importance of body fat distribution in chronic disease development, feasible methods to assess body fat are essential. This study compared dual-energy x-ray absorptiometry (DXA) in measuring visceral and subcutaneous adipose tissue (VAT and SAT) with magnetic resonance imaging (MRI).

METHODS

VAT and SAT were assessed using similar DXA and MRI protocols among 1,795 elderly participants of the Adiposity Phenotype Study (APS) and 309 children/adolescents in Shape Up! Kids (SKids). Spearman correlations, Bland-Altman plots, and coefficients of determination (R2 ) assessed agreement between DXA and MRI measures.

RESULTS

DXA overestimated SAT values in APS (315 vs. 229 cm2 ) and SKids (212 vs. 161 cm2 ), whereas DXA underestimated VAT measures (141 vs. 167 cm2 ) in adults only. The correlations between DXA and MRI values were stronger for SAT than VAT (APS: r = 0.92 vs. 0.88; SKids: 0.90 vs. 0.74). Bland-Altman plots confirmed better agreement for SAT than VAT despite differences by sex, ethnicity, and weight status with respective R2 values for SAT and VAT of 0.88 and 0.84 (APS) and 0.81 and 0.69 (SKids).

CONCLUSION

These findings indicate that SAT by DXA reflects MRI measures in children and older adults, whereas agreement for VAT is weaker for individuals with low VAT levels.

The pathophysiology of osteoporosis in obesity and type 2 diabetes in aging women and men: The mechanisms and roles of increased bone marrow adiposity

Osteoporosis is defined as a systemic skeletal disease characterized by decreased bone mass and micro-architectural deterioration leading to increased fracture risk. Osteoporosis incidence increases with age in both post-menopausal women and aging men. Among other important contributing factors to bone fragility observed in osteoporosis, that also affect the elderly population, are metabolic disturbances observed in obesity and Type 2 Diabetes (T2D). These metabolic complications are associated with impaired bone homeostasis and a higher fracture risk. Expansion of the Bone Marrow Adipose Tissue (BMAT), at the expense of decreased bone formation, is thought to be one of the key pathogenic mechanisms underlying osteoporosis and bone fragility in obesity and T2D. Our review provides a summary of mechanisms behind increased Bone Marrow Adiposity (BMA) during aging and highlights the pre-clinical and clinical studies connecting obesity and T2D, to BMA and bone fragility in aging osteoporotic women and men.

Associations of midchildhood to early adolescence central adiposity gain with cardiometabolic health in early adolescence

OBJECTIVE

This study examined the associations of central adiposity gain from midchildhood to early adolescence with cardiometabolic health markers in early adolescence.

METHODS

A total of 620 participants were studied in Project Viva. In midchildhood (mean age = 7.8 years) and early adolescence (12.9 years), waist circumference and dual-energy x-ray absorptiometry-measured visceral adipose tissue, subcutaneous abdominal adipose tissue, and trunk fat were obtained. Central adiposity gain was calculated as change per year between visits. Cardiometabolic health markers, including blood pressure, lipids, markers of insulin resistance, inflammation, and adipokines, were collected in early adolescence.

RESULTS

Greater waist circumference gain was associated with higher log triglycerides (β 0.07 mg/dL; 95% CI: 0.02-0.13), log alanine aminotransferase (0.07 U/L; 95% CI: 0.03-0.12), log high-sensitivity C-reactive protein (0.43 mg/L; 95% CI: 0.28-0.58), and other cardiometabolic markers in early adolescence. Directly measured central adiposity gains were associated with higher systolic blood pressure z score in early adolescence (visceral adipose tissue [0.13 SD units; 95% CI: 0.04-0.23], subcutaneous abdominal adipose tissue [0.18 SD units; 95% CI: 0.04-0.31], and trunk fat [0.21 SD units; 95% CI: 0.06-0.36]). These associations were independent of baseline and change in total adiposity from midchildhood to early adolescence.

CONCLUSIONS

Monitoring central adiposity gain may enable identification and intervention in children vulnerable to developing cardiometabolic health risks.

Comparison of Dual-Energy X-ray Absorptiometry and Bioelectrical Impedance Analysis in the Assessment of Body Composition in Women with Anorexia Nervosa upon Admission and Discharge from an Inpatient Specialist Unit

Assessment of body composition is fundamental in diagnosis and treatment of anorexia nervosa (AN). The gold standard dual-energy X-ray absorptiometry (DXA) is expensive and not universally available. Bioelectrical impedance analysis (BIA) is a non-invasive, inexpensive method relative to DXA. We compared DXA and BIA in the assessment of fat-free mass (FFM), fat mass (FM), and body fat percentage (BF%) in women with AN upon admission (ANT1) and discharge (ANT2) from an inpatient specialist unit with a referent healthy control (HC) group. The study population consisted of 31 ANT1, 25 ANT2, and 52 HC women with median age of 21 years. Body composition was measured by DXA and Tanita foot-to-foot BIA. Comparison between the two methods was done using Bland-Altman analysis, Pearson's correlation coefficient, Lin's concordance correlation coefficient, and linear regression. The mean difference (bias) in FM and BF% values obtained by DXA and BIA in ANT1 (FM: +1.01 kg, BF%: +2.26%) and ANT2 (FM: +1.49 kg, BF%: +1.66%) were comparable to HC (FM: -1.32 kg, BF%: -2.29%) although in opposite directions. Less bias was observed in FFM values in ANT1 (-0.46 kg) and ANT2 (-0.86 kg) than in HC (+2.03 kg); however, the limits of agreement between the two methods were wider in ANT1 and ANT2 than in HC for all measurements. No association was observed between age, percentage of total body water, and the time spent on the inpatient specialist unit with the difference in estimates of body composition between DXA and BIA. Comparison of DXA and BIA suggests that DXA should remain the gold standard for measuring body composition; the development of more specific BIA equations is required to improve validity and precision of BIA in patients with AN. Despite ease and cost in both BIA access and operation, the suitability of BIA in a low bodyweight eating disorders population remains questionable.

The East Asian gut microbiome is distinct from colocalized White subjects and connected to metabolic health

East Asians (EAs) experience worse metabolic health outcomes compared to other ethnic groups at lower body mass indices; however, the potential role of the gut microbiota in contributing to these health disparities remains unknown. We conducted a multi-omic study of 46 lean and obese East Asian and White participants living in the San Francisco Bay Area, revealing marked differences between ethnic groups in bacterial richness and community structure. White individuals were enriched for the mucin-degrading Akkermansia muciniphila. East Asian subjects had increased levels of multiple bacterial phyla, fermentative pathways detected by metagenomics, and the short-chain fatty acid end-products acetate, propionate, and isobutyrate. Differences in the gut microbiota between the East Asian and White subjects could not be explained by dietary intake, were more pronounced in lean individuals, and were associated with current geographical location. Microbiome transplantations into germ-free mice demonstrated stable diet- and host genotype-independent differences between the gut microbiotas of East Asian and White individuals that differentially impact host body composition. Taken together, our findings add to the growing body of literature describing microbiome variations between ethnicities and provide a starting point for defining the mechanisms through which the microbiome may shape disparate health outcomes in East Asians.

The community of microbes living in the human gut varies based on where a person lives, in part because of differences in diets but also due to factors still incompletely understood. In turn, this ‘microbiome’ may have wide-ranging effects on health and diseases such as obesity and diabetes.

Many scientists want to understand how differences in the microbiome emerge between people, and whether this may explain why certain diseases are more common in specific populations. Self-identified race or ethnicity can be a useful tool in that effort, as it can serve as a proxy for cultural habits (such as diets) or genetic information.

In the United States, self-identified East Asian Americans often have worse ‘metabolic health’ (e.g. levels of sugar or certain fat molecules in the blood) at a lower weight than those identifying as White. Ang, Alba, Upadhyay et al. investigated whether this health disparity was linked to variation in the gut microbiome. Samples were collected from 46 lean and obese individuals living in the San Francisco Bay Area who identified as White or East Asian.

The analyses showed that while the gut microbiome of White participants changed in association with obesity, the microbiomes of East Asian participants were distinct from their White counterparts even at normal weight, with features mirroring what was seen in White individuals in the context of obesity. Although these differences were connected to people’s current address, they were not attributable to dietary differences.

Ang, Alba, Upadhyay et al. then transplanted the microbiome of the participants into genetically identical mice with microbe-free guts. The differences between the gut microbiomes of White and East Asian participants persisted in recipient animals. When fed the same diet, the mice also gained different amounts of weight depending on the ethnic identity of the microbial donor.

These results show that self-identified ethnicity may be an important variable to consider in microbiome studies, alongside other factors such as geography. Ultimately, this research may help to design better, more personalized treatments for an array of conditions.

Accuracy of dual-energy x-ray absorptiometry for assessing longitudinal change in visceral adipose tissue in patients with coronary artery disease

BACKGROUND/OBJECTIVE

Visceral adipose tissue (VAT) is a key target of interventions for obesity-related diseases. Dual-energy x-ray absorptiometry (DXA) can estimate VAT, however its accuracy to measure longitudinal change in VAT compared to gold-standard techniques such as magnetic resonance imaging (MRI), has not been studied in adults. This study aimed to determine the accuracy of DXA compared with gold-standard MRI for cross-sectional VAT assessment, and for detecting longitudinal change in VAT.

METHODS

Adults with coronary artery disease (64 ± 8 years; BMI 27.8 ± 3.5 kg/m²; 88% male) were assessed for VAT by DXA and MRI at baseline (n = 34) and during implementation of an exercise intervention study at 3- and 12-months (n = 29). To match the 5.2 cm DXA measurement site for Hologic software (InnerCore^TM), VAT cross-sectional area (CSA) was measured by MRI using a single slice at L4/L5 junction, and VAT volume measured by 10 × 5 mm slices over the L4/L5 junction. MRI slices were quantified for VAT using semi-automated specialised software. Relationships between DXA and MRI for cross-sectional VAT and longitudinal change in VAT were determined by linear regression. Accuracy between the methods was assessed by Bland-Altman analysis, with data presented as mean difference (95% confidence interval), lower and upper limits of agreement (LoA).

RESULTS

Strong correlations were found between DXA-VAT and MRI-VAT at baseline (r = 0.90; p < 0.001), and longitudinal change in DXA-VAT and MRI-VAT over 3- and 12-months (r = 0.67; p < 0.001). In contrast, Bland-Altman analysis revealed significant overestimation by DXA-VAT volume at baseline by 13% [-104 cm³ (-157, -52 cm³), p < 0.001; LoA (-398, 189 cm³)], and underestimation of change in DXA-VAT volume over 3-months by 33% [-41 cm³ (-77, -4 cm³), p = 0.030; LoA (-228, 147 cm³)] and 12-months by 47% [-65 cm³ (-114, -17 cm³), p = 0.010; LoA (-316, 185 cm³)]. Results were similar for VAT CSA.

CONCLUSIONS

Compared with MRI, DXA substantially underestimated longitudinal changes in VAT. Therefore, DXA is not currently a valid alternative to MRI for quantifying VAT changes and may under-represent the effectiveness of interventions for obesity management.

The Influence of Laparoscopic Sleeve Gastrectomy on Body Composition and Fat Distribution in Obese Caucasian Men and Women

Background

The aim of the study was to assess changes in body composition in patients subjected to laparoscopic sleeve gastrectomy (LSG).

Methods

Changes in body composition following LSG were determined in a group of 155 patients with obesity (117 women and 38 men), with dual-energy X-ray absorptiometry (DXA). Whole body fat mass (FM) and lean body mass (LBM) were determined, and abdominal fat mass (AbdF) was assessed within the region extending from the top of the pubic bone up to the line between 12th thoracic and 1st lumbar vertebras.

Results

Over the period of 12 months following LSG, body mass index decreased by 28.2 ± 9.0% (p < 0.001). The reduction of body weight by 35.4 ± 12.6 kg (p < 0.001) was the result of a decrease in FM by 23.9 ± 8.9 kg (p < 0.001) and LBM by 10.5 ± 3.8 kg (p < 0.001). AbdF decreased from 13.2 ± 3.1 to 8.2 ± 2.7 kg (p < 0.001), but abdominal fat to total fat mass ratio increased from 24.9 ± 4.7 to 28.0 ± 5.8% (p < 0.001). The loss of AbdF was more pronounced in men than in women. The rate of FM loss was attenuated with patients’ age.

Conclusions

Over the period of 12 months following LSG, the reduction of FM was more than twice as much as decrease of LBM. The loss of AbdF was slower than a loss of peripheral subcutaneous fat.

Longitudinal associations of fruit juice intake in infancy with DXA-measured abdominal adiposity in mid-childhood and early adolescence

BACKGROUND

Excessive abdominal adiposity is associated with health risks in children and adults. Higher consumption of fruit juice and other sources of fructose has been shown to promote weight gain and specifically visceral adiposity in adulthood.

OBJECTIVES

We aimed to examine the longitudinal associations of fruit juice intake in infancy with visceral adiposity in mid-childhood and early adolescence.

METHODS

We analyzed data from 783 participants in Project Viva, a US prebirth cohort. Our exposure was fruit juice intake at 1 y old. We measured visceral adipose tissue (VAT), subcutaneous abdominal adipose tissue (SAAT), and total abdominal adipose tissue (TAAT) in mid-childhood (mean age 7.8 ± 0.7 y) and early adolescence (13 ± 0.8 y) using DXA. We examined longitudinal associations of fruit juice intake at 1 y with VAT, SAAT, and TAAT area sex-specific standard deviation scores (SDSs) in mid-childhood and early adolescence using linear mixed models. We adjusted for child age at outcome, sex, race/ethnicity, age and BMI z-score at 1 y-questionnaire, maternal prepregnancy BMI, level of education, and prenatal sugar-sweetened beverage intake, paternal BMI, and median household income at birth.

RESULTS

After adjusting for child and parental covariates, each serving (120 mL) per day of fruit juice intake at 1 y was associated with persistently greater VAT area SDS (β = 0.08; 95% CI: 0.03, 0.13) at both timepoints in boys and girls. The association of fruit juice intake with VAT appeared stronger than that with SAAT (β = 0.05; 95% CI: 0.00, 0.09) and TAAT (β = 0.05; 95% CI: 0.01, 0.10).

CONCLUSIONS

Higher fruit juice intake in infancy was associated with greater abdominal adiposity, particularly VAT, in mid-childhood and early adolescence. Our findings support limiting fruit juice intake in infancy, which can have later impact on visceral adiposity in childhood and adolescence.Clinical Trial Registry number: NCT02820402 (https://clinicaltrials.gov/ct2/show/NCT02820402).

Associations of DXA-measured abdominal adiposity with cardio-metabolic risk and related markers in early adolescence in Project Viva

BACKGROUND

Increased visceral adipose tissue (VAT) precedes development of insulin resistance and dyslipidemia in adults. The associations of abdominal adiposity derived from dual-energy X-ray absorptiometry (DXA), including VAT, subcutaneous abdominal adipose tissue (SAAT) and total abdominal adipose tissue (TAAT) with cardio-metabolic risk in adolescents are understudied.

OBJECTIVES

We examined the cross-sectional associations of DXA-measured abdominal adiposity with cardio-metabolic risk and related markers in early adolescence (mean [SD] age 13.0 [0.7] years).

METHODS

We collected data from 740 adolescents (374 girls and 366 boys) in Project Viva, a U.S. pre-birth cohort. We used DXA estimates of VAT, SAAT and TAAT area. We conducted overall and sex-stratified linear regression models, adjusting for age, sex (in overall models), race/ethnicity, puberty score and body mass index (BMI) z-score.

RESULTS

Mean BMI z-score was 0.59 (1.28). After adjustment, greater VAT (per 1 SD score) was associated with higher metabolic risk z-score (β 0.14 units; 95% CI 0.08, 0.20), higher log high-sensitivity C-reactive protein (β 0.51 mg/L; 0.36, 0.66) and log leptin (β 0.36 ng/mL; 0.27, 0.44), and lower log adiponectin (β -0.08 ug/mL; -0.13, -0.02). SAAT and TAAT showed similar associations as VAT with comparable or greater effect sizes.

CONCLUSION

In early adolescence, DXA-measured VAT, SAAT and TAAT are associated with cardio-metabolic risk and related markers, independent of current BMI. Among two adolescents with the same BMI, there is an associated higher cardio-metabolic risk in the adolescent with greater DXA-measured abdominal adiposity.

DXA Measured Visceral Adipose Tissue, Total Fat, Anthropometric Indices and its Association With Cardiometabolic Risk Factors in Mother-Daughter Pairs From India

Visceral fat is the pathogenic fat depot associated with diabetes, dyslipidemia, and cardiovascular diseases. Estimation of visceral adipose tissue (VAT) by dual energy-X-ray absorptiometry (DXA) is a newer technique with less radiation exposure, shorter scanning time, and lower cost. In this study, we attempted to look at relationship between cardiometabolic risk factors and VAT, total body fat percent (TBF%) and anthropometry. We also studied the changes in body composition and metabolic parameters with menopause. The familial resemblance of VAT and TBF% in mother-daughter pair was also compared. This was a cross sectional community study of 300 women (150 postmenopausal mothers and 150 premenopausal daughters). Body composition indices by DXA and metabolic parameters were assessed. The association between DXA-VAT, TBF%, anthropometric measures, and cardiometabolic risk factors were studied by correlation, receiver operating characteristics curves, and logistic regression analysis. VAT indices were significantly higher and lean indices lower in postmenopausal women as compared to premenopausal women. One fourth of postmenopausal women were categorized as metabolically obese normal weight. DXA-VAT was a better predictor of cardiometabolic risk factors as compared to waist circumference, body mass index, and TF% in postmenopausal women (AUC:0.68 vs 0.62, 0.60 & 0.5, respectively), whereas body mass index had a better prediction in premenopausal women(AUC:0.68). VAT area >100 cm² had a significant association with the presence of ≥2 cardiometabolic risk factors (p = 0.04, OR: 2.2, CI:1.0-4.7) in the postmenopausal women. Daughters of the mothers with higher TBF% were found to have a higher TBF% compared to daughters of mothers with normal TBF% (36.2 ± 4.2 vs 32.2 ± 4.4, p = 0.03), similar resemblance was not seen for VAT. The study showed that the VAT increases and lean mass decreases with age and menopause. DXA measured VAT is a better predictor of cardiometabolic risk in postmenopausal women but not in premenopausal women. Total body fat may have a familial resemblance, but not the VAT which is determined by age, menopause, and probable life style factors.

Chronic stress and adipose tissue in the anorexic state: endocrine and epigenetic mechanisms

Although adipose tissue metabolism in obesity has been widely studied, there is limited research on the anorexic state, where the endocrine system is disrupted by reduced adipose tissue mass and there are depot-specific changes in adipocyte type and function. Stress exposure at different stages of life can alter the balance between energy intake and expenditure and thereby contribute to the pathogenesis of anorexia nervosa. This review integrates information from human clinical trials to describe endocrine, genetic and epigenetic aspects of adipose tissue physiology in the anorexic condition. Changes in the hypothalamus-pituitary-thyroid, -adrenal, and -gonadal axes and their relationships to appetite regulation and adipocyte function are discussed. Because of the role of stress in triggering or magnifying anorexia, and the dynamic but also persistent nature of environmentally-induced epigenetic modifications, epigenetics is likely the link between stress and long-term changes in the endocrine system that disrupt homoeostatic food intake and adipose tissue metabolism. Herein, we focus on the adipocyte and changes in its function, including alterations reinforced by endocrine disturbance and dysfunctional adipokine regulation. This information is critical because of the poor understanding of anorexic pathophysiology, due to the lack of suitable research models, and the complexity of genetic and environmental interactions.

Precision of the Hologic DXA in the Assessment of Visceral Adipose Tissue

INTRODUCTION

Visceral fat, also known as visceral adipose tissue (VAT), has been the focus of intensive research over the past several yr, as ground breaking studies have investigated its possible role in predicting long-term cardiac dysfunction, hypertension, and diabetes. Historically, magnetic resonance imaging and computed tomography were the instruments of choice for visceral fat quantification. However, with the introduction of visceral fat assessment software for Dual-energy X-ray Absorptiometry (DXA) scanners, DXA's use for VAT assessment has become increasingly common. To effectively utilize DXA in future VAT research studies, information about their precision and accuracy must be known. This study provides novel information regarding the precision of the Hologic Horizon DXA scanner in the assessment of VAT.

METHODS

Sixty individuals (32.7 ± 17.1 yr, 51% male, 40% with body mass index (BMI) > 25 kg/m²) above the age of 16 years were recruited to participate in this study. Subjects found to be pregnant, have a lumbar vertebral compression fracture, nonremovable metal implants in the abdomen, or scoliosis/lordosis/kyphosis were excluded from the study. All subjects underwent 3 consecutive whole body scans on a Hologic Horizon A DXA scanner.

RESULTS

VAT mass ranged from 102 g to 1454 g. VAT precision improved with increasing BMI (p = 0.025): coefficient of variation (%CV) was 15.2% for underweight subjects (n = 2), 7.1% for healthy subjects (n = 34), 6.4% for overweight subjects (n = 18), and 4.7% for obese subjects (n = 6).

CONCLUSIONS

VAT measurement by Hologic DXA displays a satisfactory level of precision in individuals with a BMI of >18.5 kg/m². Precision was found to be higher in those with the greatest risk of cardio-metabolic dysfunction (individuals with high VAT). Due to its low cost, brief examination time, noninvasiveness, and limited radiation exposure, DXA may be considered the tool of choice for VAT determination in future studies.

Changes to Body Composition in Women With Long-Standing Established Rheumatoid Arthritis: Differences by Level of Disease Activity

INTRODUCTION

Few studies on rheumatoid arthritis have investigated disease activity and body composition by dual-energy X-ray absorptiometry including evaluation of visceral adipose tissue. Thus, we sought to verify the association between body composition by dual-energy X-ray absorptiometry, including visceral adipose tissue, and inflammatory activity in long-standing established rheumatoid arthritis.

METHODS

Seventy-eight postmenopausal women with rheumatoid arthritis (American College of Rheumatology 2010) were studied. Disease activity was assessed by composite indexes (DAS28, CDAI, SDAI) and C-reactive protein. Potential association between body composition and disease activity was analysed by Pearson correlation and Tukey´s test (p < 0.05).

RESULTS

There was significant negative correlation between C-reactive protein and appendicular lean mass index (r = -0.234, p = 0.039). After adjusting for confounding variables, women with C-reactive protein >10 mg/L had a lower appendicular lean mass index than those with C-reactive protein 5-10 mg/L and <5 mg/L (6.3 ± 0.8 kg/m² vs 7.2 ± 1.2 kg/m² vs 6.8 ± 1.0 kg/m², respectively; p = 0.013). Women with moderate inflammation (C-reactive protein 5-10 mg/L) had more fat than those with C-reactive protein >10 mg/L and C-reactive protein <5 mg/L (12.4 ± 3.5 kg/m² vs 9.9 ± 3.6 kg/m² vs 10.5 ± 2.8 kg/m², respectively; p = 0.040), as well as more visceral adipose tissue than women with higher and lower C-reactive protein (812.5 ± 266.4 cm³ vs 604.3 ± 236.3cm³ vs 658.9 ± 255.6 cm³; p = 0.009).

CONCLUSIONS

High inflammatory activity that persists after a long disease duration was associated with both lower muscle and fat mass (including visceral adipose tissue), which is suggestive of more exuberant rheumatoid cachexia. Conversely, moderate activity was associated with greater visceral adipose tissue, which is associated with increased cardiovascular risk. These results point to the existence of different body composition profiles according to inflammatory status and the importance of individualized approaches to muscle mass and adiposity according to disease activity level in long-standing rheumatoid arthritis.

Quantitative Imaging of Body Composition

Body composition refers to the amount and distribution of lean tissue, adipose tissue, and bone in the human body. Lean tissue primarily consists of skeletal muscle; adipose tissue comprises mostly abdominal visceral adipose tissue and abdominal and nonabdominal subcutaneous adipose tissue. Hepatocellular and myocellular lipids are also fat pools with important metabolic implications. Importantly, body composition reflects generalized processes such as increased adiposity in obesity and age-related loss of muscle mass known as sarcopenia.In recent years, body composition has been extensively studied quantitatively to predict overall health. Multiple imaging methods have allowed precise estimates of tissue types and provided insights showing the relationship of body composition to varied pathologic conditions. In this review article, we discuss different imaging methods used to quantify body composition and describe important anatomical locations where target tissues can be measured.

CD81 Controls Beige Fat Progenitor Cell Growth and Energy Balance via FAK Signaling

Adipose tissues dynamically remodel their cellular composition in response to external cues by stimulating beige adipocyte biogenesis; however, the developmental origin and pathways regulating this process remain insufficiently understood owing to adipose tissue heterogeneity. Here, we employed single-cell RNA-seq and identified a unique subset of adipocyte progenitor cells (APCs) that possessed the cell-intrinsic plasticity to give rise to beige fat. This beige APC population is proliferative and marked by cell-surface proteins, including PDGFRα, Sca1, and CD81. Notably, CD81 is not only a beige APC marker but also required for de novo beige fat biogenesis following cold exposure. CD81 forms a complex with αV/β1 and αV/β5 integrins and mediates the activation of integrin-FAK signaling in response to irisin. Importantly, CD81 loss causes diet-induced obesity, insulin resistance, and adipose tissue inflammation. These results suggest that CD81 functions as a key sensor of external inputs and controls beige APC proliferation and whole-body energy homeostasis.

Association of Visceral Adiposity With Pain but Not Structural Osteoarthritis

OBJECTIVE

Osteoarthritis (OA) and pain are both made more severe by low-grade inflammation. This study was undertaken to examine whether visceral fat, a major source of inflammatory cytokines and adipokines, is associated with an increased risk of knee OA or musculoskeletal pain.

METHODS

Subjects in the Multicenter Osteoarthritis Study cohort, who were age 50-79 years and had or were at high risk of knee OA, underwent whole-body dual x-ray absorptiometry (DXA) at baseline. At baseline, 30 months, and 60 months radiographs and magnetic resonance images (MRIs) of the knees were obtained, and patients were asked to score the severity of their knee pain and to identify sites of joint pain using a body homunculus. Baseline DXA scans were used to measure total body fat and visceral and subcutaneous fat in the torso. The association of fat depot size with structural outcomes (incident radiographic OA and cartilage loss and synovitis on MRI) and with pain outcomes (worsening knee pain, number of painful joints, and widespread pain) was assessed. Regression analyses were adjusted for age, sex, race, education level, smoking status, physical activity, body mass index (BMI), and depressive symptoms.

RESULTS

Of the 2,961 participants at baseline, 60.7% were women. The mean age was 62.5 years and mean BMI was 30.5 kg/m² . After adjustment for covariates, no fat measures were associated with any structural outcomes. However, total and visceral, but not subcutaneous, fat were positively associated with worsening knee pain (P = 0.0005 for total fat and P = 0.007 for visceral fat) and widespread pain (P = 0.001 for total fat and P = 0.02 for visceral fat), and the amount of visceral fat was associated with the number of painful joints (P = 0.07).

CONCLUSION

Our findings indicate that visceral fat is associated with an increased risk of musculoskeletal and widespread pain.

Comparison of single-slice CT and DXA-derived measures of central adiposity in South African women

BACKGROUND

Visceral adipose tissue (VAT) accumulation is a known risk factor for cardiometabolic diseases. Efficient imaging modalities are necessary to quantify VAT. The study assessed the agreement between dual-energy x-ray absorptiometry (DXA) and single-slice computed tomography (CT) for abdominal fat quantification in mixed-ancestry South African women, and determined if this differed by body mass index (BMI) categories.

METHODS

VAT and abdominal subcutaneous adipose tissue (SAT) were measured using single-slice CT and DXA in 132 women aged 55 (45-64) years. Participants were categorised as normal weight (BMI < 25 kg/m²), overweight (BMI: 25-29.9 kg/m²) and obese (BMI ≥ 30 kg/m²). Pearson correlation coefficients and Bland-Altman analysis were used to determine agreement between the two measurements.

RESULTS

Two thirds of the participants were obese. DXA and CT-derived measurements of abdominal VAT and SAT were significantly correlated in the overall sample (r = 0.872 and r = 0.966, both p < 0.001, respectively) and within BMI categories. DXA overestimated VAT and SAT in the overall sample and across BMI categories. In the overall sample, the mean difference (DXA-CT estimates) was 75.3 cm² (95% CI: 68.8-81.8 cm², p ≤ 0.0001) for VAT and 54.7 cm² (47.1-62.3 cm², p ≤ 0.0001) for SAT. Within increasing BMI categories, the variance between the two modalities was fixed for VAT (p = 0.359 for obese), whereas the variance for SAT was heteroscedastic (p ≤ 0.0001).

CONCLUSIONS

DXA overestimated VAT and abdominal SAT in a sample of middle-aged mixed-ancestry South African women. VAT variance was fixed in the obesity category, an indication that DXA may be valid in measuring VAT in obese people.

Body composition in anorexia nervosa: Meta-analysis and meta-regression of cross-sectional and longitudinal studies

OBJECTIVE

Clinically, anorexia nervosa (AN) presents with altered body composition. We quantified these alterations and evaluated their relationships with metabolites and hormones in patients with AN longitudinally.

METHOD

In accordance with PRISMA guidelines, we conducted 94 meta-analyses on 62 samples published during 1996-2019, comparing up to 2,319 pretreatment, posttreatment, and weight-recovered female patients with AN with up to 1,879 controls. Primary outcomes were fat mass, fat-free mass, body fat percentage, and their regional distribution. Secondary outcomes were bone mineral density, metabolites, and hormones. Meta-regressions examined relationships among those measures and moderators.

RESULTS

Pretreatment female patients with AN evidenced 50% lower fat mass (mean difference [MD]: -8.80 kg, 95% CI: -9.81, -7.79, Q = 1.01 × 10-63 ) and 4.98 kg (95% CI: -5.85, -4.12, Q = 1.99 × 10-28 ) lower fat-free mass, with fat mass preferentially stored in the trunk region during early weight restoration (4.2%, 95% CI: -2.1, -6.2, Q = 2.30 × 10-4 ). While the majority of traits returned to levels seen in healthy controls after weight restoration, fat-free mass (MD: -1.27 kg, 95% CI: -1.79, -0.75, Q = 5.49 × 10-6 ) and bone mineral density (MD: -0.10 kg, 95% CI: -0.18, -0.03, Q = 0.01) remained significantly altered.

DISCUSSION

Body composition is markedly altered in AN, warranting research into these phenotypes as clinical risk or relapse predictors. Notably, the long-term altered levels of fat-free mass and bone mineral density suggest that these parameters should be investigated as potential AN trait markers.

RESUMENOBJETIVO

Clínicamente, la anorexia nervosa (AN) se presenta con alteraciones en la composición corporal. Cuantificamos estas alteraciones y evaluamos longitudinalmente su relación con metabolitos y hormonas en pacientes con AN. MÉTODO: De acuerdo con las pautas PRISMA, realizamos 94 meta-análisis en 62 muestras publicadas entre 1996-2019, comparando hasta 2,319 pacientes mujeres en pre-tratamiento, post-tratamiento, y recuperadas en base al peso con hasta 1,879 controles. Las principales medidas fueron masa grasa, masa libre de grasa, porcentaje de grasa corporal y su distribución regional. Las medidas secundarias fueron densidad mineral ósea, metabolitos y hormonas. Las meta-regresiones examinaron las relaciones entre esas medidas y moderadores.

RESULTADOS

Las pacientes femeninas con AN pre-tratamiento mostraron un 50% menos de masa grasa (MD: -8.80 kg, CI 95%: -9.81, -7.79, Q = 1.01 × 10-63 ) y 4.98 kg (CI 95%: -5.85, -4.12, Q = 1.99 × 10-28 ) menos de masa libre de grasa, con masa grasa preferentemente almacenada en la región del tronco durante la recuperación temprana del peso (4.2%, CI 95%: -2.1, -6.2, Q = 2.30 × 10-4 ). Aunque la mayoría de los rasgos regresaron a los niveles vistos en los controles sanos después de la restauración del peso, la masa libre de grasa (MD: -1.27 kg, CI 95%: -1.79, -0.75, Q = 5.49 × 10-6 ) y la densidad mineral ósea (MD: -0.10 kg, CI 95%: -0.18, -0.03, Q = 0.01) permanecieron significativamente alteradas. DISCUSIÓN: La composición corporal es marcadamente alterada en la AN, lo que garantiza la investigación en estos fenotipos como predictores de riesgo clínico o de recaída. Notablemente, la alteración a largo plazo de los niveles de masa libre de grasa y densidad mineral ósea sugieren que estos parámetros debe ser investigados como potenciales rasgos indicadores de AN.

Fatigue, quality of life and metabolic changes in men treated with first-line enzalutamide versus abiraterone plus prednisolone for metastatic castration-resistant prostate cancer (HEAT): a randomised trial protocol

INTRODUCTION

Enzalutamide and abiraterone acetate plus prednisolone (AAP) are used in combination with androgen-deprivation therapy to further suppress the androgen stimulation of metastatic castration-resistant prostate cancer (mCRPC). First-line mCRPC treatment with enzalutamide and AAP yields similar overall survival and radiographic progression-free survival in phase III trials. Thus, treatment selection relies on patient choice, cost and side effects. The aim of this randomised trial is to investigate differences in fatigue, health-related quality of life (HRQoL) and metabolic side effects in men with mCRPC treated with first-line enzalutamide versus AAP.

METHODS AND ANALYSIS

In this ongoing open-label randomised (1:1) clinical trial, enzalutamide is compared with AAP as first-line treatment for men with mCRPC. The primary endpoint is fatigue assessed with the questionnaire Functional Assessment of Chronic Illness Therapy-Fatigue version 4. Secondary endpoints are changes in body composition (ie, fat mass, visceral adipose tissue, subcutaneous adipose tissue and lean body mass assessed with dual energy X-ray absorptiometry), glucose metabolism assessed with a 2-hour oral glucose tolerance test, serum lipids, blood pressure and HRQoL assessed with the questionnaire Functional Assessment of Cancer Therapy-Prostate (FACT-P). All study endpoints are assessed at baseline and 12-week postintervention. Blood and urine samples are collected at baseline and at time of progression on allocated treatment for future investigation of predictive and prognostic biomarkers in prostate cancer treatment. The planned sample size is 170 participants. All participants are recruited from Herlev and Gentofte Hospital, Denmark. Estimated last patient's last visit is February 2020.

ETHICS AND DISSEMINATION

The study received project approval from the National Committee on Health Research Ethics and Danish Data Protection Agency and Danish Medicines Agency (EudraCT no.: 2017-000027-99). The results of the study will be published in peer-reviewed international journals and will be presented at national and international conferences and symposiums.

TRIAL REGISTRATION NUMBER

Clinicaltrialsregister.eu (2017-000099-27).

Intra-Abdominal Adipose Tissue Quantification by Alternative Versus Reference Methods: A Systematic Review and Meta-Analysis

OBJECTIVE

This meta-analysis aimed to assess the agreement between intra-abdominal adipose tissue (IAAT) quantified by alternative methods and the reference standards, computed tomography (CT) and magnetic resonance imaging (MRI).

METHODS

MEDLINE and EMBASE electronic databases were systematically searched to identify studies that quantified IAAT thickness, area, or volume by a comparator method and CT or MRI. Using an inverse variance weighted approach (random-effects model), the mean differences and 95% limits of agreement (LoA) were pooled between methods.

RESULTS

The meta-analysis included 24 studies using four comparator methods. The pooled mean differences were -0.3 cm (95% LoA: -3.4 to 3.2 cm; P = 0.400) for ultrasound and -11.6 cm² (95% LoA: -43.1 to 19.9 cm² ; P = 0.004) for bioelectrical impedance analysis. Dual-energy x-ray absorptiometry (DXA) quantified both IAAT area and volume with mean differences of 8.1 cm² (95% LoA: -98.9 to 115.1 cm² ; P = 0.061) and 10 cm³ (95% LoA: -280 to 300 cm³ ; P = 0.808), respectively.

CONCLUSIONS

Ultrasound and DXA measure IAAT with minimal bias from CT or MRI, while bioelectrical impedance analysis systematically underestimates IAAT. However, with the exception of DXA for IAAT volume, the wide LoA caution against clinical or research use of the comparator methods and emphasize the need to optimize alternatives to the reference standards.

Association between Vitamin D Levels and Nonalcoholic Fatty Liver Disease: Potential Confounding Variables

Nonalcoholic fatty liver disease (NAFLD), historically considered to be the hepatic component of the metabolic syndrome, is a spectrum of fat-associated liver conditions, in the absence of secondary causes, that may progress to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Disease progression is closely associated with body weight or fatness, dyslipidemia, insulin resistance, oxidative stress, and inflammation. Recently, vitamin D deficiency has been linked to the pathogenesis and severity of NAFLD because of vitamin D "pleiotropic" functions, with roles in immune modulation, cell differentiation and proliferation, and regulation of inflammation. Indeed, several studies have reported an association between vitamin D and NAFLD/NASH. However, other studies have failed to find an association. Therefore, we sought to critically review the current evidence on the association between vitamin D deficiency and NAFLD/NASH, and to analyze and discuss some key variables that may interfere with this evaluation, such as host-, environment-, and heritability-related factors regulating vitamin D synthesis and metabolism; definitions of deficient or optimal vitamin D status with respect to skeletal and nonskeletal outcomes including NAFLD/NASH; methods of measuring 25(OH)D; and methods of diagnosing NAFLD as well as quantifying adiposity, the cardinal link between vitamin D deficiency and NAFLD.

Comparison of visceral fat measurement by dual-energy X-ray absorptiometry to computed tomography in HIV and non-HIV

Background/Objectives

Individuals with HIV are susceptible to visceral fat accumulation, which confers an increased risk of cardiometabolic disease. Advanced software to ascertain visceral fat content from dual-energy X-ray absorptiometry (DXA) has not been validated among this population. We sought to compare DXA with computed tomography (CT) in the measurement of visceral fat cross-sectional area (VAT) in HIV and non-HIV using Bland–Altman analyses.

Subjects/Methods

Data were combined from five previously conducted studies of individuals with HIV (n = 313) and controls without HIV (n = 144) in which paired DXA and CT scans were available. In cross-sectional analyses, DXA-VAT was compared with CT-VAT among participants with and without HIV. In longitudinal analyses, changes in VAT over time were compared between DXA and CT among participants with and without HIV receiving no intervention over 12 months and among individuals with HIV receiving tesamorelin—a medication known to reduce VAT—over 6 months.

Results

In HIV, DXA underestimated VAT compared with CT among individuals with increased visceral adiposity. The measurement bias was −9 ± 47 cm² overall, but became progressively larger with greater VAT (P < 0.0001), e.g., −61 ± 58 cm² among those with VAT ≥ 200 cm². Sex-stratified analyses revealed that the relationship between VAT and measurement bias was especially pronounced in men (P < 0.0001). Longitudinally, DXA underestimated changes in VAT, particularly among those at the extremes of VAT gain or loss (P < 0.0001). In contrast to the cross-sectional findings, the tendency for DXA to underestimate longitudinal changes in VAT was evident in both men and women. Analogous findings were seen among controls in cross-sectional and longitudinal analyses.

Conclusions

DXA underestimated VAT relative to CT in men with and without HIV, who had increased visceral adiposity. DXA also underestimated changes in VAT over time in men and women, irrespective of HIV status. DXA-VAT should be used with caution among both HIV and non-HIV-infected populations.

Accuracy of Longitudinal Assessment of Visceral Adipose Tissue by Dual-Energy X-Ray Absorptiometry in Children with Obesity

BACKGROUND

Increased visceral adipose tissue (VAT) is strongly associated with cardiometabolic risk factors. Accurate quantification of VAT is available through magnetic resonance imaging (MRI), which incurs a significant financial and time burden. We aimed to assess the accuracy of dual-energy X-ray absorptiometry- (DXA-) derived VAT (DXA-VAT) against a gold standard MRI protocol (MRI-VAT) in children with normal weight and obesity cross-sectionally, and over the course of a lifestyle intervention.

METHODOLOGY

MRI-VAT and DXA-VAT were quantified in 61 children (30 normal weight and 31 with obesity) at baseline. Children with obesity entered a three-month exercise and/or nutrition intervention after which VAT was reassessed. MRI- and DXA-VAT cross-sectional area, volume, and mass were quantified, and associations were calculated at baseline (n = 61) and pre-post intervention (n = 28, 3 participants dropped out). Method agreement was assessed through Bland-Altman analysis, linear regression, and Passing-Bablok regression.

RESULTS

At baseline, all DXA- and MRI-VAT outcomes were strongly associated (r = 0.90, P < 0.001). However, there were no significant associations between absolute or relative change in DXA- and MRI-VAT outcomes (r = 0.25-0.36, P > 0.05). DXA significantly overestimated VAT CSA (cross-sectional area), volume, and mass when compared with MRI (P < 0.001) at baseline. Significant proportional bias was observed for all DXA-VAT outcomes at baseline and for relative longitudinal changes in DXA-VAT.

CONCLUSIONS

Although DXA-VAT outcomes were strongly associated with MRI-VAT outcomes at baseline, estimates were subject to proportional bias in children with obesity and normal weight. DXA lacks validity for detecting changes in VAT among children with obesity. This trial is registered with NCT01991106.

Subcutaneous Fat Fibrosis Links Obesity to Insulin Resistance in Chinese Americans

OBJECTIVE

Type 2 diabetes presents at a lower body mass index (BMI) in Chinese individuals than in white individuals. We sought to determine the role of subcutaneous adipose tissue (SCAT)-intrinsic factors, vs BMI or adiposity per se, in the vulnerability of Chinese individuals to obesity-associated impairment of insulin sensitivity.

RESEARCH DESIGN AND METHODS

Thirty-two Chinese and 30 white men and women from a cohort in the San Francisco Bay Area underwent anthropometric measurements, body composition (dual-energy X-ray absorptiometry) analyses, and measurement of fasting plasma glucose and insulin. Forty-eight also provided abdominal SCAT samples for transcriptional and biochemical analyses of tissue fibrosis.

RESULTS

BMI correlated with total body fat in white (r = 0.74, P < 0.001) but not Chinese individuals, whereas BMI correlated with visceral adipose tissue (VAT) accrual in both ethnicities (r = 0.88 and 0.81, respectively; P < 0.01). Insulin resistance (homeostatic model assessment of insulin resistance) worsened with VAT mass, but not total body fat, in Chinese subjects (r = 0.63, P < 0.01), whereas it worsened with both in white individuals. By contrast, SCAT mRNA levels of genes encoding profibrotic proteins rose remarkably along with both BMI and VAT mass in Chinese but not white subjects. Similarly, SCAT levels of hydroxyproline, an indicator of tissue collagen content that correlated with increasing VAT mass, were higher in Chinese vs white subjects, particularly in the setting of relative insulin resistance.

CONCLUSIONS

Our findings dissociate BMI from adiposity in Chinese individuals and instead highlight SCAT fibrosis as a process linked to visceral adiposity and insulin resistance in this group.

Sex Differences in Body Composition

Body composition differs between men and women. Men have more lean mass, and women have more fat mass than men. Men are more likely to accumulate adipose tissue around the trunk and abdomen, whereas women usually accumulate adipose tissue around the hips and thighs. Less is known about sex differences in ectopic fat depots. Advances in imaging allow the noninvasive assessment of abdominal and femorogluteal fat compartments, intramyocellular lipids, intrahepatic lipids, pericardial adipose tissue, and neck adipose tissue including brown adipose tissue and tongue adipose tissue. In this review, sex differences of regional adipose tissue, muscle mass, ectopic lipids, and brown adipose tissue and their effects on cardiometabolic risk will be discussed. In addition, novel imaging techniques to quantify these body composition compartments noninvasively will be described.

The effect of growth hormone on bioactive IGF in overweight/obese women

OBJECTIVE

Overweight/obesity is characterized by decreased growth hormone (GH) secretion whereas circulating IGF-I levels are less severely reduced. Yet, the activity of the circulating IGF-system appears to be normal in overweight/obese subjects, as estimated by the ability of serum to activate the IGF-I receptor in vitro (bioactive IGF). We hypothesized that preservation of bioactive IGF in overweight/obese women is regulated by an insulin-mediated suppression of IGF-binding protein-1 (IGFBP-1) and IGFBP-2, and by suppression of IGFBP-3, mediated by low GH. We additionally hypothesized that increases in bioactive IGF would drive changes in body composition with low-dose GH administration.

DESIGN

Cross-sectional analysis and 3-month interim analysis of a 6-month randomized, placebo-controlled study of GH administration in 50 overweight/obese women without diabetes mellitus. Bioactive IGF (kinase receptor activation assay) and body composition (DXA) were measured.

RESULTS

Prior to treatment, IGFBP-3 (r = -0.33, p = 0.02), but neither IGFBP-1 nor IGFBP-2, associated inversely with bioactive IGF. In multivariate analysis, lower IGFBP-3 correlated with lower peak stimulated GH (r = 0.45, p = 0.05) and higher insulin sensitivity (r = -0.74, p = 0.003). GH administration resulted in an increase in mean serum IGF-I concentrations (144 ± 56 to 269 ± 66 μg/L, p < 0.0001) and bioactive IGF (1.29 ± 0.39 to 2.60 ± 1.12 μg/L, p < 0.0001). The treatment-related increase in bioactive IGF, but not total IGF-I concentration, predicted an increase in lean mass (r = 0.31, p = 0.03) and decrease in total adipose tissue/BMI (r = -0.43, p = 0.003).

CONCLUSIONS

Our data suggest that in overweight/obesity, insulin sensitivity and GH have opposing effects on IGF bioactivity through effects on IGFBP-3. Furthermore, increases in bioactive IGF, rather than IGF-I concentration, predicted GH administration-related body composition changes.

CLINICAL TRIAL REGISTRATION NUMBER

NCT00131378.

High-Fat Diet-Induced Obesity Promotes Expansion of Bone Marrow Adipose Tissue and Impairs Skeletal Stem Cell Functions in Mice

Obesity represents a risk factor for development of insulin resistance and type 2 diabetes. In addition, it has been associated with increased adipocyte formation in the bone marrow (BM) along with increased risk for bone fragility fractures. However, little is known on the cellular mechanisms that link obesity, BM adiposity, and bone fragility. Thus, in an obesity intervention study in C57BL/6J mice fed with a high-fat diet (HFD) for 12 weeks, we investigated the molecular and cellular phenotype of bone marrow adipose tissue (BMAT), BM progenitor cells, and BM microenvironment in comparison to peripheral adipose tissue (AT). HFD decreased trabecular bone mass by 29%, cortical thickness by 5%, and increased BM adiposity by 184%. In contrast to peripheral AT, BMAT did not exhibit pro-inflammatory phenotype. BM progenitor cells isolated from HFD mice exhibited decreased mRNA levels of inflammatory genes (Tnfα, IL1β, Lcn2) and did not manifest an insulin resistant phenotype evidenced by normal levels of pAKT after insulin stimulation as well as normal levels of insulin signaling genes. In addition, BM progenitor cells manifested enhanced adipocyte differentiation in HFD condition. Thus, our data demonstrate that BMAT expansion in response to HFD exerts a deleterious effect on the skeleton. Continuous recruitment of progenitor cells to adipogenesis leads to progenitor cell exhaustion, decreased recruitment to osteoblastic cells, and decreased bone formation. In addition, the absence of insulin resistance and inflammation in the BM suggest that BMAT buffers extra energy in the form of triglycerides and thus plays a role in whole-body energy homeostasis. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals, Inc.

Short bowel syndrome: influence of nutritional therapy and incretin GLP1 on bone marrow adipose tissue

Energy deprivation leads to a decrease in white adipose tissue and bone mineral density (BMD), while simultaneously inducing the expansion of marrow adipose tissue (MAT). In short bowel syndrome (SBS), parenteral nutrition mitigates the deterioration of nutritional status, including decreases in MAT. Osteoporosis is, however, a frequent complication of SBS. The objective of our study here was to evaluate the association of fat deposit sites (subcutaneous and visceral adipose tissues: intrahepatic lipid (IHL) and MAT) and the incretin glucagon-like peptide 1 (GLP1) with BMD in individuals with SBS. MAT was negatively correlated with lumbar spine BMD in normal individuals, but not in those in the SBS group, who otherwise showed a positive correlation between MAT and GLP1. In addition, in individuals with SBS, IHL was negatively associated with lumbar spine BMD and positively associated with C-terminal telopeptide of type 1 collagen (a serum biomarker of bone turnover). Caloric maintenance in individuals with SBS, therefore, seems to positively affect the relationship between MAT and BMD, which may be modulated, at least in part, by GLP1.

Quantification of visceral adipose tissue in polycystic ovary syndrome: dual-energy X-ray absorptiometry versus magnetic resonance imaging

Background Polycystic ovary syndrome (PCOS) is associated with frequent overweight and abdominal obesity. Quantifying visceral adipose tissue (VAT) in PCOS patients can be a tool to assess metabolic risk and monitor effects of treatment. The latest dual-energy X-ray absorptiometry (DXA) technology can measure VAT and subcutaneous adipose tissue (SAT) in a clinical setting. Purpose To compare DXA-measurements of VAT and SAT with the gold standard MRI in women with PCOS. Material and Methods A cross-sectional study of 67 overweight women with PCOS was performed. Measurements of VAT and SAT were performed by DXA in a 5-cm thick transverse slice at the L4/L5 level and by MRI in a 1-cm thick transverse slice at the L3 level. Results Mean (SD) DXA-VAT was 81 (34) cm³, DXA-SAT was 498 (118) cm³, MRI-VAT was 117 (48) cm³, and MRI-SAT was 408 (122) cm³. MRI and DXA measures of VAT (r = 0.82, P < 0.001) and SAT (r = 0.92, P < 0.001) correlated closely, and DXA-VAT was stronger correlated with MRI-VAT than BMI (r = 0.62, P < 0.001) and waist circumference (r = 0.60, P < 0.001). DXA-VAT coefficient of variance was 6.7% and inter correlation coefficient was 0.98. Bland-Altman analyses showed DXA to slightly underestimate VAT and SAT measurements compared with MRI. Conclusion DXA and MRI measurements of VAT and SAT correlated closely despite different size of region of interest, and DXA-VAT was superior to waist circumference and BMI in estimating MRI-VAT. DXA showed high reproducibility making it is suitable for repeated measurements in the same individual over time.

Age-Related Changes in Fat Mass and Distribution in Men-the Cross-Sectional STRAMBO Study

Data on age-related differences in fat mass and distribution in men are scarce. We performed a cross-sectional analysis of age-related differences in fat distribution in men. In a cohort of 1133 men aged 20-87 yr, body composition was assessed using a Hologic Discovery A device. We assessed fat mass (FM) and FM indices adjusted for height. Interindividual variability was calculated as standard deviation, interquartile range, and difference between the 95th and 5th percentiles in 5-yr age groups. After adjustment for lifestyle factors, the FM and FM index of appendicular, gynoid, central, android, and subcutaneous abdominal compartments increased with age. Their variability did not vary with age. Visceral FM was 181% higher in men aged >80 yr compared to men aged 20-30 yr, and the variability increased with age. FM in the central, android, subcutaneous abdominal, and visceral compartments correlated with age significantly more strongly before the age of 70 than after this age. The relative differences between the elderly and younger men were greater for visceral FM than for subcutaneous (abdominal and appendicular) fat. The interindividual variability in visceral FM is higher in elderly men. The association between visceral FM and age is stronger before the age of 70.

Dose-response effects of aerobic exercise on body composition among colon cancer survivors: a randomised controlled trial

Background:

Physical activity is associated with a lower risk of disease recurrence among colon cancer survivors. Excess visceral adipose tissue is associated with a higher risk of disease recurrence among colon cancer survivors. The pathways through which physical activity may alter disease outcomes are unknown, but may be mediated by changes in visceral adipose tissue.

Methods:

Thirty-nine stage I–III colon cancer survivors were randomised to one of three groups: usual-care control, 150 min wk⁻¹ of aerobic exercise (low dose) and 300 min wk⁻¹ of aerobic exercise (high dose) for 6 months. The prespecified key body composition outcome was visceral adipose tissue quantified using dual energy X-ray absorptiometry.

Results:

Exercise reduced visceral adipose tissue in dose–response fashion (P_trend=0.008). Compared with the control group, the low- and high-dose exercise groups lost 9.5 cm² (95% CI: –22.4, 3.5) and 13.6 cm² (95% CI: –27.0, –0.1) in visceral adipose tissue, respectively. Each 60 min wk⁻¹ increase in exercise predicted a 2.7 cm² (95% CI: –5.4, –0.1) reduction in visceral adipose tissue.

Conclusions:

Aerobic exercise reduces visceral adipose tissue in dose–response fashion among patients with stage I–III colon cancer. Visceral adipose tissue may be a mechanism through which exercise reduces the risk of disease recurrence among colon cancer survivors.

DXA-assessed changes in body composition in obese women following two different weight loss programs

OBJECTIVE

Changes in body composition during weight loss programs might have a significant effect on long-term results. The aim of this study was to test these changes by dual energy x-ray absorptiometry (DXA) in obese women enrolled into two different weight loss medical programs.

METHODS

We prospectively studied 71 women assigned to either an intensive 3-mo cognitive-behavioral therapy (CBT) or a 1-mo nutritional counseling plan (NCP). All patients underwent DXA whole-body scan before treatment and after 3, 6, and 12 mo. Fat mass (FM), non-bone lean mass (LM) and bone mineral content were assessed at whole-body and regional levels. Android visceral adipose tissue (VAT) also was estimated.

RESULTS

Twenty-three patients missed one or more follow-up controls and were excluded from the final analysis. Twenty-seven patients (body mass index [BMI] 41.9 ± 6.7 kg/m²) remained in the CBT group and 21 (BMI 33.4 ± 4 kg/m²) in the NCP group. The progressive decrease of BMI in both groups was associated with reduced whole-body and regional FM, which was more marked in CBT. During follow-up, a progressive decrease of total FM-to-LM and android FM-to-LM ratios were observed both in CBT (Δ12-mo versus baseline -7.8 ± 9.6% and -9.5 ± 12.7%, respectively; P < 0.01) and NCP (Δ12-mo versus baseline -5.9 ± 9.6% and -7 ± 13.4%, respectively; P < 0.05). VAT was the parameter showing the largest decrease (-14.2 ± 17.4% and -11.3 ± 18.2% at 12 mo, respectively in CBT and NCP; P < 0.05).

CONCLUSIONS

Lifestyle-induced weight loss is associated with selective changes in body composition parameters, regardless of initial BMI and treatment program, limiting sarcopenic obesity. DXA may quantify the metabolically healthier redistribution of total and regional FM and VAT.

Oxytocin and Its Relationship to Body Composition, Bone Mineral Density, and Hip Geometry Across the Weight Spectrum

CONTEXT

Oxytocin (OXT), an anorexigenic hypothalamic hormone anabolic to bone, may reflect energy availability. Basal serum OXT levels are lower in anorexia nervosa (AN, state of energy deficit) than healthy controls (HC) and negatively associated with spine bone mineral density (BMD). Reports are conflicting regarding OXT levels in overweight/obesity (OB, state of energy excess). Relationships between OXT and BMD in OB and hip geometry across the weight spectrum are unknown.

OBJECTIVE

To determine whether overnight serum OXT levels are (1) elevated in OB and (2) associated with body composition, BMD, and hip geometry across the weight spectrum.

DESIGN

Cross-sectional.

SETTING

Clinical research center.

PARTICIPANTS

Fifty-nine women, ages 18 to 45 years: amenorrheic AN (N = 16), eumenorrheic HC (N = 24), eumenorrheic OB (N = 19).

MAIN OUTCOME MEASURES

Serum sampled every 20 minutes from 8 pm to 8 am and pooled for integrated overnight OXT levels. Body composition, BMD, and hip structural analysis measured by dual x-ray absorptiometry.

RESULTS

OXT levels were lowest in AN, higher in HC, and highest in OB (P ≤ 0.02). There were positive associations between OXT and (1) body mass index (P = 0.0004); (2) total, visceral, and subcutaneous fat (P ≤ 0.0002); (3) spine and hip BMD Z-scores (P ≤ 0.01); and (4) favorable hip geometry, namely buckling ratio (P ≤ 0.05). In a subset analysis of HC and OB, relationships between OXT and body composition, but not bone parameters, remained significant.

CONCLUSIONS

These data suggest OXT is a marker of energy availability and may be a mediator of bone density, structure, and strength. OXT pathways may provide targets for obesity and osteoporosis treatment.

Body Fat Distribution Ratios and Obstructive Sleep Apnea Severity in Youth With Obesity

STUDY OBJECTIVES

Obesity and regional fat distribution, measured by neck fat mass percentage using dual-energy X-ray absorptiometry (DXA), correlate with obstructive sleep apnea (OSA) severity in adults. In obese children, neck-to-waist-circumference ratio predicts OSA. This study examined associations between body fat percentage and distribution and sleep-disordered breathing (SDB) severity in obese youth, measured with DXA.

METHODS

Cross-sectional retrospective study conducted at a tertiary children's hospital. Participants were aged 6 to 18 years with obesity (body mass index [BMI] > 99th percentile [BMI z-score 2.35] or > 95th percentile with comorbidity). They underwent polysomnography and DXA to quantify body fat percentage and distribution ratios (neck-to-abdominal fat percentage [NAF % ratio]). SDB was defined as apnea-hypopnea index (AHI) > 5 and OSA as obstructive AHI (OAHI) > 1 event/h. Relationships of BMI z-score and NAF % ratio to log AHI and log OAHI were evaluated.

RESULTS

Thirty individuals participated; 18 male; median age 14.1 years. Twenty-four individuals had BMI z-scores > 2.35. Ten had AHI > 5 events/h. NAF % ratio was significantly associated with log AHI in males and with log OAHI in all, whereas total fat mass percent was not. The association between log OAHI and NAF % ratio was significant in males, but not females. NAF % ratio was significantly associated with log OAHI in those with BMI z-score above 2.35.

CONCLUSIONS

NAF % ratio was associated with OSA severity in males and youth with BMI > 99th percentile; however, total fat mass percentage was not, suggesting that body fat distribution is associated with OSA risk in youth.

Visceral fat measured by DXA is associated with increased risk of non-spine fractures in nonobese elderly women: a population-based prospective cohort analysis from the São Paulo Ageing & Health (SPAH) Study

The present study investigates the relationship between visceral fat measured by dual-energy X-ray absorptiometry (DXA) and the incidence of non-spine fractures in community-dwelling elderly women. We demonstrated a potential negative effect of visceral fat on bone health in nonobese women.

INTRODUCTION

The protective effect of obesity on bone health has been questioned because visceral fat has been demonstrated to have a deleterious effect on bone. The aim of this study was to investigate the association of visceral fat measured by DXA with the incidence of non-spine fractures in community-dwelling elderly women.

METHODS

This longitudinal prospective population-based cohort study evaluated 433 community-dwelling women aged 65 years or older. A specific clinical questionnaire, including personal history of a fragility fracture in non-spine osteoporotic sites, was administered at baseline and after an average of 4.3 years. All incidences of fragility fractures during the study period were confirmed by affected-site radiography. Visceral adipose tissue (VAT) was measured in the android region of a whole-body DXA scan.

RESULTS

The mean age was 72.8 ± 4.7 years, and 28 incident non-spine osteoporotic fractures were identified after a mean follow-up time of 4.3 ± 0.8 years. According to the Lipschitz classification for nutritional status in the elderly, 38.6 % of women were nonobese (BMI ≤ 27 kg/m²) and 61.4 % were obese/overweight. Logistic regression models were used to estimate the relationship between VAT and non-spine fractures in elderly women. After adjusting for age, race, previous fractures, and BMD, VAT (mass, area, volume) had a significant association with the incidence of non-spine fractures only in nonobese elderly women (VAT mass: OR, 1.42 [95 % CI, 1.09-1.85; p = 0.010]; VAT area: OR, 1.19 [95 % CI, 1.05-1.36; p = 0.008]; VAT volume: OR, 1.40 [95 % CI, 1.09-1.80; p = 0.009]).

CONCLUSION

This study suggests a potential negative effect of visceral adiposity on bone health in nonobese women.

Anorexia Nervosa: Analysis of Trabecular Texture with CT

Purpose To determine indexes of skeletal integrity by using computed tomographic (CT) trabecular texture analysis of the lumbar spine in patients with anorexia nervosa and normal-weight control subjects and to determine body composition predictors of trabecular texture. Materials and Methods This cross-sectional study was approved by the institutional review board and compliant with HIPAA. Written informed consent was obtained. The study included 30 women with anorexia nervosa (mean age ± standard deviation, 26 years ± 6) and 30 normal-weight age-matched women (control group). All participants underwent low-dose single-section quantitative CT of the L4 vertebral body with use of a calibration phantom. Trabecular texture analysis was performed by using software. Skewness (asymmetry of gray-level pixel distribution), kurtosis (pointiness of pixel distribution), entropy (inhomogeneity of pixel distribution), and mean value of positive pixels (MPP) were assessed. Bone mineral density and abdominal fat and paraspinal muscle areas were quantified with quantitative CT. Women with anorexia nervosa and normal-weight control subjects were compared by using the Student t test. Linear regression analyses were performed to determine associations between trabecular texture and body composition. Results Women with anorexia nervosa had higher skewness and kurtosis, lower MPP (P < .001), and a trend toward lower entropy (P = .07) compared with control subjects. Bone mineral density, abdominal fat area, and paraspinal muscle area were inversely associated with skewness and kurtosis and positively associated with MPP and entropy. Texture parameters, but not bone mineral density, were associated with lowest lifetime weight and duration of amenorrhea in anorexia nervosa. Conclusion Patients with anorexia nervosa had increased skewness and kurtosis and decreased entropy and MPP compared with normal-weight control subjects. These parameters were associated with lowest lifetime weight and duration of amenorrhea, but there were no such associations with bone mineral density. These findings suggest that trabecular texture analysis might contribute information about bone health in anorexia nervosa that is independent of that provided with bone mineral density. ^© RSNA, 2016.

Comparison of visceral fat mass measurement by dual-X-ray absorptiometry and magnetic resonance imaging in a multiethnic cohort: the Dallas Heart Study

Background/Objectives:

Visceral adipose tissue (VAT) mass, a risk factor for cardiometabolic complications of obesity, is usually measured by magnetic resonance imaging (MRI) but this method is not practical in a clinical setting. In contrast, measurement of VAT by dual-x-ray absorptiometry (DXA) appears to circumvent the limitations of MRI. In this study, we compared measurements of VAT mass by MRI and DXA in the large, multiethnic cohort of the Dallas Heart Study (DHS).

Subjects/Methods:

About 2689 DHS participants underwent paired measurement of VAT by MRI and DXA. Sex-stratified analyses were performed to evaluate the correlation and agreement between DXA and MRI. Model validation was performed using bootstrapping and inter-reader variability was assessed.

Results:

Mean age of the cohort was 44 years, with 55% female, 48% Black and 75% overweight/obese participants. Regression analysis showed a linear relationship between DXA and MRI with R²=0.82 (95% confidence interval (CI) 0.81–0.84) for females and R²=0.86 (95% CI 0.85–0.88) for males. Mean difference between methods was 0.01 kg for females and 0.09 kg for males. Bland–Altman analysis showed that DXA tended to modestly underestimate VAT compared with MRI at lower VAT levels and overestimate it compared with MRI at higher VAT levels. Results were consistent in analyses stratified by race, body mass index status, waist girth and body fat. Inter-individual reader correlation among 50 randomly selected scans was excellent (inter-class correlation coefficient=0.997).

Conclusions:

VAT mass quantification by DXA was both accurate and valid among a large, multiethnic cohort within a wide range of body fatness. Further studies including repeat assessments over time will help determine its long-term applicability.

Body composition predictors of skeletal integrity in obesity

OBJECTIVE

To determine body composition predictors of skeletal integrity in overweight/obese subjects using dual energy X-ray absorptiometry (DXA). We hypothesized that visceral adiposity would be negatively, and lean mass positively, associated with DXA measures of skeletal integrity in obesity.

MATERIALS AND METHODS

Our study was institutional review board (IRB)-approved and Health Insurance Portability and Accountability Act (HIPAA)-compliant and written informed consent was obtained. We studied 82 overweight or obese, but otherwise healthy premenopausal women and men of similar age who were part of a clinical trial (mean age: 37 ± 10 years, mean BMI: 34 ± 7 kg/m(2)). All subjects underwent DXA of the spine and hip for assessment of bone mineral density (BMD), trabecular bone score (TBS), and hip structural analysis (HSA), and of the whole body for the assessment of body composition, including estimated visceral adipose tissue (VAT).

RESULTS

Sixty-three subjects (77 %) had normal BMD and 19 subjects (23 %) had osteopenia. There were strong age-, sex-, and BMD-independent positive associations between lean mass and HSA parameters (r = 0.50 to r = 0.81, p < 0.0001), whereas there was no association with TBS. There were strong age-, sex- and BMD-independent inverse associations between total fat and VAT mass and TBS (r = -0.60 and r = -0.72, p < 0.0001 for both correlations), whereas there were no associations with HSA parameters.

CONCLUSION

Lean mass is a positive predictor of hip geometry, whereas fat and VAT mass are negative predictors of trabecular microarchitecture in overweight/obese subjects.

The Dose-Response Effects of Aerobic Exercise on Body Composition and Breast Tissue among Women at High Risk for Breast Cancer: A Randomized Trial

Observational data indicate that behaviors that shift energetic homeostasis, such as exercise, may decrease the risk of developing breast cancer by reducing the amount of energy-dense, metabolically active adipose tissue. Between December 2008 and April 2013, we conducted a single-blind, 5-month, clinical trial that randomized premenopausal women at high risk of developing breast cancer to one of three groups: 150 min/wk of aerobic exercise (low dose), 300 min/wk of aerobic exercise (high dose), or control. Body composition was assessed using dual-energy x-ray absorptiometry. Background parenchymal enhancement (BPE) was quantified using computerized algorithms on breast dynamic contrast-enhanced MRI. Over 5 months, compared with the control group: the low-dose and high-dose groups lost -1.5 ± 0.5 and -1.3 ± 0.5 kg of body mass (linear Ptrend = 0.032); -1.5 ± 0.4 and -1.4 ± 0.3 kg of fat mass (linear Ptrend = 0.003); -1.3 ± 0.3 and -1.4 ± 0.3% of body fat (linear Ptrend < 0.001); -15.9 ± 5.4 and -26.6 ± 5.0 cm(2) of subcutaneous adipose tissue (linear Ptrend < 0.001); and -6.6 ± 1.9 and -5.0 ± 1.9 cm(2) visceral adipose tissue (nonlinear Ptrend = 0.037). For each -1 cm(2) reduction in visceral adipose tissue, BPE decreased by -3.43 ± 1.34 cm(2) (P = 0.010) and explained 9.7% of the variability in BPE. Changes in other aforementioned body composition outcomes did not significantly correlate with changes in BPE. These mechanistic data support observational evidence that shifting energetic homeostasis through exercise may alter the risk of developing breast cancer. Additional adequately powered studies are needed to confirm and expand upon our findings that changes in body composition are associated with changes in BPE. Cancer Prev Res; 9(7); 581-8. ©2016 AACR.

A randomized phase II dose-response exercise trial among colon cancer survivors: Purpose, study design, methods, and recruitment results

BACKGROUND

Observational studies indicate that higher volumes of physical activity are associated with improved disease outcomes among colon cancer survivors. The aim of this report is to describe the purpose, study design, methods, and recruitment results of the courage trial, a National Cancer Institute (NCI) sponsored, phase II, randomized, dose-response exercise trial among colon cancer survivors.

METHODS/RESULTS

The primary objective of the courage trial is to quantify the feasibility, safety, and physiologic effects of low-dose (150 min·week(-1)) and high-dose (300 min·week(-1)) moderate-intensity aerobic exercise compared to usual-care control group over six months. The exercise groups are provided with in-home treadmills and heart rate monitors. Between January and July 2015, 1433 letters were mailed using a population-based state cancer registry; 126 colon cancer survivors inquired about participation, and 39 were randomized onto the study protocol. Age was associated with inquiry about study participation (P<0.001) and randomization onto the study protocol (P<0.001). No other demographic, clinical, or geographic characteristics were associated with study inquiry or randomization. The final trial participant was randomized in August 2015. Six month endpoint data collection was completed in February 2016.

DISCUSSION

The recruitment of colon cancer survivors into an exercise trial is feasible. The findings from this trial will inform key design aspects for future phase 2 and phase 3 randomized controlled trials to examine the efficacy of exercise to improve clinical outcomes among colon cancer survivors.

Vertebral Strength and Estimated Fracture Risk Across the BMI Spectrum in Women

Somewhat paradoxically, fracture risk, which depends on applied loads and bone strength, is elevated in both anorexia nervosa and obesity at certain skeletal sites. Factor-of-risk (Φ), the ratio of applied load to bone strength, is a biomechanically based method to estimate fracture risk; theoretically, higher Φ reflects increased fracture risk. We estimated vertebral strength (linear combination of integral volumetric bone mineral density [Int.vBMD] and cross-sectional area from quantitative computed tomography [QCT]), vertebral compressive loads, and Φ at L4 in 176 women (65 anorexia nervosa, 45 lean controls, and 66 obese). Using biomechanical models, applied loads were estimated for: 1) standing; 2) arms flexed 90°, holding 5 kg in each hand (holding); 3) 45° trunk flexion, 5 kg in each hand (lifting); 4) 20° trunk right lateral bend, 10 kg in right hand (bending). We also investigated associations of Int.vBMD and vertebral strength with lean mass (from dual-energy X-ray absorptiometry [DXA]) and visceral adipose tissue (VAT, from QCT). Women with anorexia nervosa had lower, whereas obese women had similar, Int.vBMD and estimated vertebral strength compared with controls. Vertebral loads were highest in obesity and lowest in anorexia nervosa for standing, holding, and lifting (p < 0.0001) but were highest in anorexia nervosa for bending (p < 0.02). Obese women had highest Φ for standing and lifting, whereas women with anorexia nervosa had highest Φ for bending (p < 0.0001). Obese and anorexia nervosa subjects had higher Φ for holding than controls (p < 0.03). Int.vBMD and estimated vertebral strength were associated positively with lean mass (R = 0.28 to 0.45, p ≤ 0.0001) in all groups combined and negatively with VAT (R = -[0.36 to 0.38], p < 0.003) within the obese group. Therefore, women with anorexia nervosa had higher estimated vertebral fracture risk (Φ) for holding and bending because of inferior vertebral strength. Despite similar vertebral strength as controls, obese women had higher vertebral fracture risk for standing, holding, and lifting because of higher applied loads from higher body weight. Examining the load-to-strength ratio helps explain increased fracture risk in both low-weight and obese women.