Differential impacts of cardiac and abdominal ectopic fat deposits on cardiometabolic risk stratification

Epicardial Adipose Tissue Thickness and Preserved Ejection Fraction Heart Failure

PURPOSE OF THE REVIEW

Preserved ejection fraction heart failure and obesity frequently coexist. Whether obesity plays a consistent role in the pathogenesis of preserved ejection fraction heart failure is unclear. Accumulation of visceral adiposity underlies the pathogenic aftermaths of obesity. However, visceral adiposity imaging is assessed by computed tomography or magnetic resonance and thus not routinely available. In contrast, epicardial adiposity thickness is assessed by echocardiography and thus routinely available. We review the rationale for assessing epicardial adiposity thickness in patients with preserved ejection fraction heart failure and elevated body mass index.

RECENT FINDINGS

Body mass index correlates poorly with visceral, and epicardial adiposity. Visceral and epicardial adiposity enlarges as preserved ejection fraction heart failure progresses. Epicardial adiposity may hasten the progression of coronary artery disease and impairs left ventricular sub-endocardial perfusion and diastolic function. Epicardial adiposity thickness may help monitor the therapeutic response in patients with preserved ejection failure heart failure and elevated body mass index.

Serum and Adipose Dipeptidyl Peptidase 4 in Cardiovascular Surgery Patients: Influence of Dipeptidyl Peptidase 4 Inhibitors

Dipeptidyl peptidase 4 (DPP-4) is a novel adipokine and may be involved in the association between adipose tissue and metabolic syndrome. We investigated DPP-4 and adiponectin levels in the serum, subcutaneous adipose tissue (SAT), and epicardial adipose tissue (EAT), and their relationship with preoperative factors, as well as comparing the DPP-4 levels in SAT and EAT with and without DPP-4 inhibitors. This study included 40 patients (25 men, age 67.5 ± 13.8 years). The serum adipokine, DPP-4, and adiponectin levels in SAT and EAT were measured using ELISA and Western blotting. The DPP-4 and adiponectin levels were significantly higher in the SAT than in the EAT. The serum DPP-4 and DPP-4 activity levels had no correlation with the DPP-4 levels in the SAT and EAT, but the DPP-4 levels in the SAT and EAT had a positive correlation. The DPP-4 levels in the SAT were positively correlated with atherosclerosis, diabetes mellitus, DPP-4-inhibitor use, and fasting blood glucose. The DPP-4 levels in the EAT showed a negative correlation with eGFR and a positive correlation with atrial fibrillation. The DPP-4 activity in the serum had a lower tendency in the group taking DPP-4 inhibitors than in the group not taking them. DPP-4 inhibitors may suppress angiogenesis and adipose-tissue hypertrophy.

Adipokine gene expression in adipocytes isolated from different fat depots of coronary artery disease patients

To compare DPP4, LCN2, NAMPT, ITLN1, APLN mRNA levels in adipocytes isolated from the biopsies of subcutaneous, epicardial and perivascular fat obtained from 25 patients with coronary artery disease. Gene expression signature was determined by RT-qPCR with hydrolysis probes. We found DPP4 and APLN mRNA was higher expressed only in adipocytes isolated from epicardial adipose tissue compared to the subcutaneous fat. The ITLN1 gene was overexpressed in epicardial adipose tissue compared to both subcutaneous and perivascular tissues. APLN mRNA expression was positively correlated with total and LDL cholesterol plasma level, and DPP4 mRNA expression - with VLDL cholesterol concentration. Thus, adipocytes isolated from different adipose depots are characterised by differential gene expression of adipokines. Epicardial adipose tissue is of particular interest in the context of its function, molecular and genetic mechanisms of regulation of the cardiovascular system and as a therapeutic target for correction of adipose tissue-induced effects on health.

Natural course of coronary artery calcium progression in Asian population with an initial score of zero

Background

We aimed to investigate the natural course of coronary artery calcium progression in an Asian population with a baseline coronary artery calcium (CAC) score of zero, and to determine subclinical coronary atherosclerosis.

Methods

Four hundred fifty-nine subjects with at least two CAC scans with an initial score of zero were included. CAC progression (+) was defined by the development of any CAC (i.e., CAC > 0) during subsequent CT scans. Clinical characteristics and Framingham risk profiles were also recorded.

Results

Among 459 subjects, 106 (23.09%) experienced CAC progression during the average follow-up period of 5.71 ± 2.68 years. Older age, male gender, HDL-C, total cholesterol and higher Framingham risk score were independently associated with CAC progression. Framingham risk score had the better discriminative ability (AUC = 0.660) to predict CAC progression compared to the other parameters with a sensitivity of 75.24% and specificity of 53.95%. For the double zero score with coronary artery atherosclerosis prediction, older age, triglycerides, hypertension, and Framingham risk score were significantly associated with these events. Among these parameters, Framingham risk score may be a relatively acceptable parameter with high negative predictive (NPV = 96.4%) value to rule out double zero score with obstructive coronary artery atherosclerosis scenario with an optimum cut-off value of <16.9 (AUC =0.652, sensitivity of 57.69%; specificity of 68.82%).

Conclusions

A baseline zero CAC score in asymptomatic Chinese population with low to intermediate risk have a low incidence for CAC progression within the 5-years period. For CAC progression prediction, Framingham risk score with the cutoff < 11.1 may help confirm subjects at low risk to improve cardiovascular risk stratification and reclassification in the field of preventive cardiology.

Voxel-wise Study of Cohort Associations in Whole-Body MRI: Application in Metabolic Syndrome and Its Components

Background The metabolic syndrome is related to obesity and ectopic fat distribution. Purpose To investigate whether an image analysis approach that uses image registration for whole-body voxel-wise analysis could provide additional information about the relationship between metabolic syndrome and body composition compared with traditional image analysis. Materials and Methods Whole-body quantitative water-fat MRI was performed in a population-based prospective study on obesity, energy, and metabolism between October 2010 and November 2016. Fat mass was measured with dual-energy x-ray absorptiometry (DXA). Whole-body voxel-wise analysis of tissue volume and fat content was applied in more than 2 million voxels from the whole-body examinations by automated interindividual deformable image registration of the water and fat MRI data. Metabolic syndrome was diagnosed by the harmonized National Cholesterol Education Program criteria. Two-tailed t tests were used and P values less than .05 were considered to indicate statistical significance. Results This study evaluated 167 women and 159 men (mean age, 50 years) by using voxel-wise analysis. Metabolic syndrome (13.5%; 44 of 326) was related to traditional measurements of fat distribution, such as total fat mass at DXA, visceral and subcutaneous adipose tissue, and liver and pancreatic fat at MRI. Voxel-wise analysis found metabolic syndrome related to liver, heart, and perirenal fat volume; fat content in subcutaneous fat in the hip region in both sexes; fatty infiltration of leg muscles in men, especially in gluteus maximus; and pericardial and aortic perivascular fat mainly in women. Sex differences in associations with subcutaneous adipose tissue were identified. In women, metabolic syndrome diagnosis was linked to regional differences in associations to adipose tissue volumes in upper versus lower body, and dorsal versus ventral abdominal depots. In men similar gradients were only seen in individual components. Conclusion In addition to showing the relationships between metabolic syndrome and body composition in a detailed and intuitive fashion in the whole body, the voxel-wise analysis provided additional information compared with traditional image analysis. © RSNA, 2020 Online supplemental material is available for this article.

The relationship of circulating fibroblast growth factor 21 levels with pericardial fat: The Multi-Ethnic Study of Atherosclerosis

Previous small studies have reported an association between circulating fibroblast growth factor 21 (FGF21) levels and pericardial fat volume in post-menopausal women and high cardiovascular disease (CVD) risk patients. In this study, we investigated the relationship of FGF21 levels with pericardial fat volume in participants free of clinical CVD at baseline. We analysed data from 5765 men and women from the Multi-Ethnic Study of Atherosclerosis (MESA) with both pericardial fat volume and plasma FGF21 levels measured at baseline. 4746 participants had pericardial fat volume measured in at least one follow-up exam. After adjusting for confounding factors, ln-transformed FGF21 levels were positively associated with pericardial fat volume at baseline (β = 0.055, p < 0.001). When assessing change in pericardial fat volume over a mean duration of 3.0 years using a linear mixed-effects model, higher baseline FGF21 levels were associated with higher pericardial fat volume at baseline (2.381 cm³ larger in pericardial fat volume per one SD increase in ln-transformed FGF21 levels), but less pericardial fat accumulation over time (0.191 cm³/year lower per one SD increase in ln-transformed FGF21 levels). Cross-sectionally, higher plasma FGF21 levels were significantly associated with higher pericardial fat volume, independent of traditional CVD risk factors and inflammatory markers. However, higher FGF21 levels tended to be associated with less pericardial fat accumulation over time. Nevertheless, such change in pericardial fat volume is very modest and could be due to measurement error. Further studies are needed to elucidate the longitudinal relationship of baseline FGF21 levels with pericardial fat accumulation.

[Expression of gene and content of adiponectin in fatty tissue in patients with ischemic heart disease]

The purpose of the study was to investigate the features of expression and adiponectin content in the adipocyte culture of subcutaneous, epicardial, and perivascular adipose tissue and the effect of various doses of rosuvastatin on these processes. 29 patients with coronary artery disease were examined. Adipocytes were isolated from the samples of SAT, EAT and PVAT which were taken during coronary artery bypass surgery, followed by cultivation in the presence of rosuvastatin and evaluation of gene expression and adiponectin concentration. Adipocytes SAT, EAT and PVAT differed in the level of adiponectin secretion and expression of its gene. On day 1 of cultivation the expression of the adiponectin gene in the EAT was 2.3 times lower than in the PVAT. On day 2 of cultivation the expression of the adiponectin gene was reduced both in the EAT and the PVAT as compared to the SAT. When rosuvastatin was added at a concentration of 1 mmol/L, adiponectin gene expression in PVAT was higher than when rosuvastatin was added at a concentration of 5 mmol/L, in the adipocyte culture of SAT effect was opposite. Thus, the adipocytes of EZhT and, to a greater extent, PAS, can be a therapeutic target for statins in the case of the pathological activation of adipose tissue.

Is echocardiographic epicardial fat thickness increased in patients with coronary artery disease? A systematic review and meta-analysis

Background

The relation of epicardial fat thickness (EFT) to coronary artery disease (CAD) has recently been reported in multiple studies. Echocardiography is a safe and relatively inexpensive and accessible approach to assess regional EFT, which can be performed easily in many centers.

Objective

To determine the association between echocardiographic EFT and the presence or the absence of CAD.

Methods

This was a systematic review and meta-analysis conducted on literature available in electronic databases up to March 2018. The articles measuring EFT by echocardiography in the right ventricular (RV) free wall were included in the study. The quality of the enrolled items was assessed using the Methodological Index for Non-Randomized Studies (MINORS) checklist. The analyses were performed using the Comprehensive Meta-Analysis version 2 software. Cochran’s Q test and I² index were used to evaluate heterogeneity.

Results

This meta-analysis was performed on 13 studies involving 2,436 patients (1,622 with CAD, and 814 without CAD). The maximum EFT reported by echocardiography was 12.9±2.7 mm in the CAD group and 8.4±2.5 mm in the non-CAD group. The minimum EFT reported by echocardiography was 2.2±1.8 mm in the CAD group and 1.8±1.4 mm in the non-CAD group. The heterogeneity was found among the researched studies (I²=91.8%, p=0.000, Q-value=146.43, df [Q] =12) using the random effect model. The patients with CAD had a significantly higher echocardiographic EFT than those without CAD (SMD=1.03, 95% CI= 0.70–1.37, p=0.000).

Conclusion

According to the findings of this meta-analysis, the echocardiographic EFT in the subjects with CAD was significantly higher than that of those without CAD. The measurement of echocardiographic EFT seems to be an acceptable strategy for risk stratification of heart diseases considering ease of use, cost-effectiveness and non-exposure characteristics, compared to other imaging interventions.

Anthropometric indices as surrogates for estimating abdominal visceral and subcutaneous adipose tissue: A meta-analysis with 16,129 participants

AIM

To seek anthropometric indices that estimate visceral and subcutaneous adipose tissue (VAT and SAT) by meta-analysis and comparing the predictive efficacy based on different characteristics of participants.

METHODS

PubMed, PubMed Central, Web of Science, China National Knowledge Infrastructure and Wanfang databases were searched for publications containing correlation coefficients of VAT and/or SAT with waist circumference (WC) and/or body mass index (BMI). The overall or subgroup pooled results were analyzed by meta and metafor packages of R with random effects model. MedCalc software was used to compare the correlation coefficients between groups.

RESULTS

Twenty-nine publications were included in this meta-analysis. The correlation coefficients of VAT-WC, VAT-BMI, SAT-WC and SAT-BMI for total studies were between 0.640 and 0.785. The correlation of VAT with WC was larger than that with BMI (Z = 11.664, P < 0.001). Meanwhile, the correlation coefficients of VAT-WC were statistically different among different age groups, areas, ethnicities, body shapes, scanning levels, units and instruments of measuring VAT (P < 0.05). The overall correlation of SAT with BMI was larger than that with WC (Z = 3.805, P < 0.001). The subgroups' correlation coefficients of SAT-BMI showed statistical differences between genders, age groups, areas, ethnicities, body shapes, scanning levels, units (cm² and cm³) and instruments of measuring SAT (P < 0.05).

CONCLUSIONS

WC may be a common and simple surrogate for estimating VAT, and BMI for SAT, especially in Europeans, but not in the aged people.

The role of pericardial adipose tissue in the heart of obese minipigs

BACKGROUND

Pericardial adipose tissue (PAT) volume is highly associated with the presence and severity of cardiometabolic diseases, but the underlying mechanism is unknown. We previously demonstrated that a high-fat diet (HFD) induced metabolic dysregulation, cardiac fibrosis and accumulation of more PAT in minipigs. This study used our obese minipig model to investigate the characteristics of PAT and omental visceral fat (VAT) induced by a HFD, and the potential link between PAT and HFD-related myocardial fibrosis.

MATERIALS AND METHODS

Five-month-old Lee-Sung minipigs were made obese by feeding a HFD for 6 months.

RESULTS

The HFD induced dyslipidemia, cardiac fibrosis and more fat accumulation in the visceral and pericardial depots. The HFD changes the fatty acid composition in the adipose tissue by decreasing the portion of linoleic acid in the VAT and PAT. No arachidonic acid was detected in the VAT and PAT of control pigs, whereas it existed in the same tissues of obese pigs fed the HFD. Compared with the control pigs, elevated levels of malondialdehyde and TNFα were exhibited in the plasma and PAT of obese pigs. HFD induced greater size of adipocytes in VAT and PAT. Higher levels of GH, leptin, OPG, PDGF, resistin, SAA and TGFβ were observed in obese pig PAT compared to VAT.

CONCLUSION

This study demonstrated the similarities and dissimilarities between PAT and VAT under HFD stimulus. In addition, this study suggested that alteration in PAT contributed to the myocardial damage.

Correlations between the abdominal fat-related parameters and severity of coronary artery disease assessed by computed tomography

Background

Obesity is considered a challenging public problem, which has been proven to be closely associated with coronary artery disease (CAD). Each risk factor of CAD has been separately studied many times in the past, but very few have comprehensively and quantitatively evaluated the relationship between the abdominal fat-related parameters and severity of CAD. The aim of this study was to analyze whether the abdominal fat-related parameters were associated with severity of CAD using abdominal non-enhanced computed tomography (NECT).

Methods

Patients who went through both abdominal NECT and invasive coronary angiography (ICA) were included and retrospectively analyzed. The abdominal fat-related parameters [the ratio of visceral adipose tissue to subcutaneous adipose tissue (VAT/SAT ratio)] and traditional cardiovascular risk factors were evaluated in the participants with or without obstructive CAD. The correlations between the abdominal fat-related parameters and severity of CAD were assessed, and the multivariable logistic regression analysis was performed to investigate the parameters that could be used to predict the severity of CAD.

Results

A total of 223 consecutive subjects (obstructive CAD group, n=117; non-obstructive CAD group, n=106) were analyzed. The VAT/SAT ratio was significantly higher (0.95±0.33 vs. 0.70±0.25, P<0.001) in obstructive CAD (O-CAD) patients than that in non-obstructive CAD (NO-CAD) patients. There was a trend to having nonalcoholic fatty liver disease (NAFLD) in the O-CAD patients than that of NO-CAD (P=0.002); the abdominal aortic calcification (AAC) score in O-CAD patients were higher than that in NO-CAD patients (P<0.001). The multivariable logistic regression analysis demonstrated that VAT/SAT ratio, NAFLD, and AAC score were independent predictors of O-CAD after adjusting the traditional cardiovascular risk factors. The area under the curve (AUC) of the combination of the above risk factors is 0.85, which leads to an increase in AUC than each risk factor alone in differentiating patients with or without O-CAD.

Conclusions

VAT/SAT ratio, NAFLD, and AAC score are correlated with the severity of CAD, indicating their characteristics of being independent risk factors for O-CAD, irrespective of the traditional cardiovascular risk factors. Those CT-derived parameters may make positive contributions to the differentiation of the patients with increased risk of O-CAD.

Visceral and Intrahepatic Fat Are Associated with Cardiometabolic Risk Factors Above Other Ectopic Fat Depots: The Framingham Heart Study

BACKGROUND

We examined the associations among 8 different fat depots accumulated in various anatomic regions and the relationship between these fat depots and multiple cardiometabolic risk factors.

METHODS

Participants were from the Framingham Heart Study Offspring and Third Generation who also participated in the multidetector computed tomography substudy in 2002-2005. Exposures were multidetector computed tomography-derived fat depots, including abdominal subcutaneous adipose tissue, abdominal visceral adipose tissue, intramuscular fat, intrathoracic fat, pericardial fat, thoracic periaortic fat, intrahepatic fat, and renal sinus fat. Multivariable-adjusted regression analyses with a forward selection procedure were performed to identify the most predictive fat depots.

RESULTS

Of 2529 participants, 51.9% were women (mean age, 51.1 years). Visceral adipose tissue had the strongest correlations with each of the other fat measures (range, 0.26-0.77) and with various cardiometabolic risk factors (range, -0.34 to 0.39). As determined by the selection models, visceral adipose tissue was the only fat depot that was associated with all cardiometabolic risk factors evaluated in this study (all P<.05). Selection models also showed that subcutaneous adipose tissue and intrahepatic fat were associated with cardiometabolic risk factors related to the traits of dysglycemia, dyslipidemia, and hypertension (all P<.05). However, only associations with visceral adipose tissue and intrahepatic fat persisted after further adjustment for body mass index and waist circumference.

CONCLUSIONS

Visceral adipose tissue and intrahepatic fat were consistent correlates of cardiometabolic risk factors, above and beyond standard anthropometric indices. Our data provide important insights for understanding the associations between variations in fat distribution and cardiometabolic abnormalities.

Visceral adipose tissue in patients with severe mental illness

Background Severe mental illnesses (SMIs), i.e. major depression, schizophrenia and bipolar disorder, are associated with an elevated risk for the development of type-2 diabetes mellitus and cardiovascular disorders. Several factors have been associated with increased cardiometabolic morbidity and mortality in SMI, including lifestyle factors (smoking, inactivity, unhealthy diet), endocrine and immunologic alterations; however, the underlying mechanisms remain to be fully uncovered. It is now well accepted that visceral adipose tissue (VAT) promotes the development of cardiometabolic disorders, at least in part by inflammatory and metabolic functions. Methods This paper reviews studies concerning VAT, with special focus on intra-abdominal and pericardial adipose tissue, in SMI. Results In patients with SMI, several studies have been performed concerning VAT. Most of these studies reported alterations of VAT particularly in patients with major depression and schizophrenia, independent of body weight and body mass index. Some of the studies also reported an increased cardiometabolic risk. Conclusion Patients with SMI are at increased risk of developing cardiometabolic disorders, and display increased amounts of VAT. As studies so far were mainly performed on patients before the onset of cardiometabolic disorders, VAT may serve as a biomarker for patients with SMI to assess cardiometabolic risks beyond established risk scores. Further, interventions aiming at reducing VAT in SMI are highly recommended in long-term multimodal treatment plans.

The effect of diet or exercise on ectopic adiposity in children and adolescents with obesity: a systematic review and meta-analysis

OBJECTIVE

Ectopic fat depostion in youth with obesity is associated with an increased cardiovascular disease risk. The aim of this meta-analysis was to summarize the evidence for the use of diet and/or exercise on ectopic adiposity in this population.

METHODS

A systematic literature search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement. Clinical trials that assessed ectopic fat deposition and included study arms with diet and/or exercise were searched in PubMed, PEDro and the Cochrane database.

RESULTS

Hepatic fat content and intramyocellular lipid content were described in nine studies and three studies, respectively. Most studies included teenagers, and study duration ranged between 3 and 12 months without follow-up. Using random-effects weights, the standardized mean difference of the change in hepatic adiposity (totalling 320 subjects) was -0.54 Hedges' g (95% confidence interval: -0.69 to -0.38 with p < 0.0001). By re-expressing this effect size, it is seen that diet and/or exercise results in an absolute reduction of intrahepatic lipid with 2%, which accords with a relative reduction up to 70%. Although there were significant ameliorations of insulin sensitivity, no significant changes in intramyocellular lipid were observed.

CONCLUSIONS

This meta-analysis showed that diet and/or exercise is effective to reduce hepatic adiposity in youth with obesity.

Morphometric measurements of systemic atherosclerosis and visceral fat: Evidence from an autopsy study

Background

Morphometric measurements of systemic atherosclerosis and direct quantification of visceral fat are only possible using materials from autopsy studies. However, the few autopsy studies that have investigated the association of visceral fat with atherosclerosis had small sample sizes and focused on coronary arteries of young or middle-aged White subjects. We aimed to investigate the association of pericardial fat (PF) and abdominal visceral fat (AVF) with atherosclerosis in the aorta, coronary, carotid, and cerebral arteries in a large autopsy study.

Materials and methods

We evaluated deceased subjects aged 30 years or above. We dissected and weighted the PF and the AVF and evaluated the atherosclerotic burden in the aorta, as well as the carotid, coronary, and cerebral arteries using morphometric measurements. We also investigated the interaction of PF and AVF with age regarding the atherosclerotic burden.

Results

The mean age of the 240 included subjects was 64.8±15.3 years, and 63% was male. Greater PF was associated with a higher degree of aortic atherosclerosis after adjusting for confounding variables (coefficient = 4.39, 95% CI = 0.83; 7.94, p = 0.02). Greater AVF was associated with a higher coronary stenosis index (coefficient = 1.49, 95% CI = 0.15; 2.83, p = 0.03) and a greater number of coronary plaques (coefficient = 0.71, 95% CI = 0.24; 1.19, p = 0.003). We did not find an association of PF or AVF with carotid or cerebral atherosclerotic burden. We found a significant interaction of AVF (coefficient = -0.08; 95% CI = -0.14; -0.02, p = 0.009) and PF (coefficient = -0.87, 95% CI = -1.70; -0.04, p = 0.04) with age regarding carotid artery atherosclerotic burden.

Conclusions

Greater AVF was associated with greater atherosclerotic burden and extent in coronary arteries, while greater PF correlated with a higher degree of atherosclerosis in the aorta.

Adipokine and Cytokine Profiles of Epicardial and Subcutaneous Adipose Tissue in Patients with Coronary Heart Disease

The content of adipokines, pro- and anti-inflammatory cytokines were studied in adipocytes isolated from epicardial and subcutaneous adipose tissue of 24 coronary heart disease patients. The content of leptin and soluble leptin receptor in adipocytes of epicardial adipose tissue was higher by 28.6 and 56.9% and the level of adiponectin was lower by 33% than in adipocytes of the subcutaneous fat. In culture of epicardial adipocytes, the levels of proinflammatory cytokines TNF-α and IL-1 were higher. Subcutaneous adipose tissue adipocytes were characterized by higher levels of anti-inflammatory cytokines IL-10 and FGF-β. In epicardial adipocytes of coronary heart disease patients, the concentrations of leptin, TNF-α, and IL-1 were higher, while the levels of defense regulatory molecules (adiponectin, IL-10, and FGF-β) were lower than in subcutaneous adipocytes.

Abdominal adiposity and low physical activity are independently and inversely associated with bone mineral density

BACKGROUND AND METHODS

Obesity is a highly heterogeneous condition, and the link between adiposity distribution profiles and skeletal health is not well understood. This study examined the association between adiposity and bone mineral density (BMD) in a large cohort (5268 individuals) of US adults aged 20-85 years.

RESULTS

Body mass index (BMI) and moderate-to-vigorous physical activity were positively associated with BMD. Conversely, abdominal adiposity was negatively associated with BMD, even after adjusting for age, race, BMI, and objectively-measured physical activity.

CONCLUSIONS

These findings highlight the negative influence of abdominal adiposity on BMD and contradict the notion that excess fat mass is protective for bone health.