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1.
Effects of exercise intervention on visceral fat in obese children and adolescents.
Jung, HC, Jeon, S, Lee, NH, Kim, K, Kang, M, Lee, S
The Journal of sports medicine and physical fitness. 2019;(6):1045-1057
Abstract
INTRODUCTION This meta-analysis study was aimed to assess the effects of exercise intervention on visceral fat in obese children and adolescents. EVIDENCE ACQUISITION Electronic database searches were performed in Academic Search Complete, CINAHL, Healthsource, MEDLINE, and SportDiscus, and from the earliest record to November 2017. Keywords included "exercise or training," "visceral fat," and "child or adolescent or youth." The inclusion criteria for eligible studies were as follows: 1) subjects were obese at baseline; 2) aged 6-19 years; 3) visceral fat was reported at baseline and after an intervention; and 4) studies were published in peer-reviewed journals written in English. EVIDENCE SYNTHESIS A total of 207 studies were observed at the initial search and 73 effect sizes (ESs) were derived from the 34 selected studies. The overall exercise intervention effect was large (Cohen's d [ES]=-1.003, 95% CI=-1.114, -0.892). Moderator analyses results showed that gender (Qb=8.23, df=2, P=0.016), exercise type (Qb=10.68, df=2, P=0.005), and intervention length (Qb=24.71, df=2, P<0.001) influenced the overall ES. CONCLUSIONS The group of both boys and girls (ES=-0.95) who participated combined exercise program (Aerobic + Resistance training; ES=-1.17) for 12 months (ES=-1.24) appeared to be the most effective exercise strategy for reducing visceral fat in obese youth.
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2.
Intra-Abdominal Adipose Tissue Quantification by Alternative Versus Reference Methods: A Systematic Review and Meta-Analysis.
Murphy, J, Bacon, SL, Morais, JA, Tsoukas, MA, Santosa, S
Obesity (Silver Spring, Md.). 2019;(7):1115-1122
Abstract
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.
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Is epicardial fat depot associated with atrial fibrillation? A systematic review and meta-analysis.
Gaeta, M, Bandera, F, Tassinari, F, Capasso, L, Cargnelutti, M, Pelissero, G, Malavazos, AE, Ricci, C
Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology. 2017;(5):747-752
Abstract
AIMS: Atrial fibrillation (AF) is the leading rhythm disorder in western countries. A direct relationship between left atrium (LA) enlargement and electromechanical remodelling has been established. A causative link between epicardial fat (EF), visceral adipose tissue deposited around the heart, and AF has been hypothesized. Several reports suggested the association between EF and the presence of AF. The aim of this study was to verify the relationship between AF and EF depot, performing a meta-analysis of observational case series studies. METHODS AND RESULTS Studies were identified by searching electronic databases by two independent investigators using 'atrial fibrillation' and 'epicardial fat' as keywords. Comparisons between healthy participants and AF cases were performed using a random effect meta-analysis estimating standardized mean difference among comparison groups. Meta regression was used to address the effect given by potential biological and technical confounders. Through a search result of 502 articles, only 7 were selected to conduct the present study. The comparison between all AF with respect to healthy participants resulted in a 32.0 ml of EF difference (95% confidence interval (CI) = 21.5, 42.5) showing that EF volume is higher in AF cases. A statistical significant difference of EF was observed when comparing both persistent and paroxysmal AF subtypes with respect to healthy participants (EF difference 48.0 ml (95% CI = 25.2, 70.8) and 15.7 ml (95% CI = 10.1, 21.4) for persistent and paroxysmal, respectively). A significant EF difference resulted also when comparing persistent to paroxysmal AF subtypes (29.6 ml (95% CI = 12.7, 46.5)). CONCLUSIONS The present work expands the strength of previously reported association between EF amount and atrial arrhythmia.
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Subcutaneous fat loss is greater than visceral fat loss with diet and exercise, weight-loss promoting drugs and bariatric surgery: a critical review and meta-analysis.
Merlotti, C, Ceriani, V, Morabito, A, Pontiroli, AE
International journal of obesity (2005). 2017;(5):672-682
Abstract
Aim of this review is to compare visceral and subcutaneous fat loss with all available strategies (diet and exercise, weight-loss promoting agents and bariatric surgery). Eighty-nine studies, all full papers, were analyzed to evaluate visceral and subcutaneous fat changes, measured through ultrasound, computerized tomography, magnetic resonance imaging and expressed as thickness, weight, area and volume. Studies were included in a meta-analysis (random-effects model). Intervention effect (absolute and percent changes of visceral and subcutaneous fat) was expressed as standardized mean differences, with 95% confidence intervals. Publication bias was formally assessed. The result was that subcutaneous fat was greater than visceral fat when measured as area, volume and weight, not as thickness; decrease of subcutaneous fat was greater than visceral fat when measured as area, volume and weight, not as thickness; percent decrease of visceral fat was always greater than percent decrease of subcutaneous fat, with no differences between different strategies. No intervention preferentially targets visceral fat. Basal visceral fat depots are smaller than basal subcutaneous fat depots. Visceral fat loss is linked to subcutaneous fat loss. With all strategies, percent decrease of visceral fat prevails on subcutaneous fat loss.
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5.
Exercise and ectopic fat in type 2 diabetes: A systematic review and meta-analysis.
Sabag, A, Way, KL, Keating, SE, Sultana, RN, O'Connor, HT, Baker, MK, Chuter, VH, George, J, Johnson, NA
Diabetes & metabolism. 2017;(3):195-210
Abstract
Ectopic adipose tissue surrounding the intra-abdominal organs (visceral fat) and located in the liver, heart, pancreas and muscle, is linked to cardio-metabolic complications commonly experienced in type 2 diabetes. A systematic review and meta-analysis was performed to determine the effect of exercise on ectopic fat in adults with type 2 diabetes. Relevant databases were searched to February 2016. Included were randomised controlled studies, which implemented≥4 weeks of aerobic and/or resistance exercise and quantified ectopic fat via magnetic resonance imaging, computed tomography, proton magnetic resonance spectroscopy or muscle biopsy before and after intervention. Risk of bias and study quality was assessed using Egger's funnel plot test and modified Downs and Black checklist, respectively. Of the 10,750 studies retrieved, 24 were included involving 1383 participants. No studies were found assessing the interaction between exercise and cardiac or pancreas fat. One study assessed the effect of exercise on intramyocellular triglyceride concentration. There was a significant pooled effect size for the meta-analysis comparing exercise vs. control on visceral adiposity (ES=-0.21, 95% CI: -0.37 to -0.05; P=0.010) and a near-significant pooled effect size for liver steatosis reduction with exercise (ES=-0.28, 95% CI: -0.57 to 0.01; P=0.054). Aerobic exercise (ES=-0.23, 95% CI: -0.44 to -0.03; P=0.025) but not resistance training exercise (ES=-0.13, 95% CI: -0.37 to 0.12; P=0.307) was effective for reducing visceral fat in overweight/obese adults with type 2 diabetes. These data suggest that exercise effectively reduces visceral and perhaps liver adipose tissue and that aerobic exercise should be a key feature of exercise programs aimed at reducing visceral fat in obesity-related type 2 diabetes. Further studies are required to assess the relative efficacy of exercise modality on liver fat reduction and the effect of exercise on pancreas, heart, and intramyocellular fat in type 2 diabetes and to clarify the effect of exercise on ectopic fat independent of weight loss.
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The Effect of Diet or Exercise on Visceral Adipose Tissue in Overweight Youth.
Vissers, D, Hens, W, Hansen, D, Taeymans, J
Medicine and science in sports and exercise. 2016;(7):1415-24
Abstract
OBJECTIVE Excess visceral adipose tissue (VAT) in children with obesity is associated with the development of cardiovascular and metabolic disease. This meta-analysis investigated if lifestyle interventions can reduce VAT in overweight and obese youth. METHODS Pubmed, Cochrane, and PEDro were searched for clinical trials that objectively assessed VAT and included study arms with supervised diet, exercise, or a combination of both. If there was a no-therapy control group, the data of the control group and the intervention groups were used to meta-analyze the data. In all other cases, the preintervention and the postintervention data were used to meta-analyze. Effect sizes were calculated as standardized mean differences or changes of VAT and expressed as Hedges' g. RESULTS The overall weighted mean effect size on VAT of all included interventions was -0.69 (95% confidence interval [CI] = -0.90 to -0.48) (P < 0.001). Subgroup analysis showed that the overall weighted mean effect size of diet-only interventions on VAT was 0.23 (95% CI = -0.22 to 0.68) (P = 0.311). Interventions that combined diet and exercise showed a pooled effect size on VAT of -0.55 (95% CI = -0.75 to -0.39) (P < 0.001). The pooled effect size of exercise-only interventions on VAT was -0.85 (95% CI = -1.20 to -0.57) (P < 0.001). CONCLUSIONS Supervised exercise-only or combined diet and exercise interventions can reduce VAT in overweight and obese children and adolescents. The strongest effect was found in exercise-only groups. However, high-quality randomized controlled trials describing the effect of supervised dietary interventions on VAT in children are lacking.
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Visceral adiposity and colorectal adenomas: dose-response meta-analysis of observational studies.
Keum, N, Lee, DH, Kim, R, Greenwood, DC, Giovannucci, EL
Annals of oncology : official journal of the European Society for Medical Oncology. 2015;(6):1101-1109
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Abstract
BACKGROUND Obesity-related hormonal and metabolic perturbations implicated in colorectal carcinogenesis are mainly driven by visceral adipose tissue (VAT) rather than subcutaneous adipose tissue (SAT). Yet, most epidemiologic studies have examined the relationship between excess adiposity and colorectal neoplasia using body mass index (BMI) and waist circumference (WC). Due to the inability of BMI and WC to distinguish VAT from SAT, they are likely to have underestimated the true association. PATIENTS AND METHODS We conducted a dose-response meta-analysis to summarize the relationships between VAT and colorectal adenomas and to examine the value of VAT as an independent risk factor beyond BMI, WC, and SAT. PubMed and Embase were searched through September 2014 to identify relevant observational studies. The summary odds ratio (OR) 95% confidence interval (CI) were estimated using a random-effects model. RESULTS In linear dose-response meta-analysis, the summary OR for each 25 cm(2) increase in VAT area was 1.13 (95% CI 1.05-1.21; I(2) = 62%; 6 studies; 2776 cases; range of VAT area = 30-228 cm(2)). The dose-response curve suggested no evidence of nonlinearity (Pnon-linearity = 0.37). In meta-analysis comparing the highest versus lowest category of VAT based on 12 studies, a positive association between VAT and adenomas remained statistically significant even after adjustment for BMI, WC, and SAT. In contrast, adjustment for VAT substantially attenuated associations of BMI, WC, and SAT with adenomas. Across the studies, VAT was more strongly associated with advanced adenomas than nonadvanced adenomas. CONCLUSIONS VAT may be the underlying mediator of the observed associations of BMI and WC with adenomas, increasing adenoma risk continuously over a wide range of VAT area. Considering that the joint use of BMI and WC better captures VAT than the use of either one, clinicians are recommended to use both BMI and WC to identify those at high risk for colorectal neoplasia.
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The effects of abdominal lipectomy in metabolic syndrome components and insulin sensitivity in females: A systematic review and meta-analysis.
Seretis, K, Goulis, DG, Koliakos, G, Demiri, E
Metabolism: clinical and experimental. 2015;(12):1640-9
Abstract
BACKGROUND Adipose tissue is an endocrine organ, which is implicated in the pathogenesis of obesity, metabolic syndrome and diabetes. Lipectomy offers a unique opportunity to permanently reduce the absolute number of fat cells, though its functional role remains unclear. This systematic and meta-analysis review aims to assess the effect of abdominal lipectomy on metabolic syndrome components and insulin sensitivity in women. METHODS A predetermined protocol, established according to the Cochrane Handbook's recommendations, was used. An electronic search in MEDLINE, Scopus, the Cochrane Library and CENTRAL electronic databases was conducted from inception to May 14, 2015. This search was supplemented by a review of reference lists of potentially eligible studies and a manual search of key journals in the field of plastic surgery. Eligible studies were prospective studies with ≥1month of follow-up that included females only who underwent abdominal lipectomy and reported on parameters of metabolic syndrome and insulin sensitivity. RESULTS The systematic review included 11 studies with a total of 271 individuals. Conflicting results were revealed, though most studies showed no significant metabolic effects after lipectomy. The meta-analysis included 4 studies with 140 subjects. No significant changes were revealed between lipectomy and control groups. CONCLUSIONS This meta-analysis provides evidence that abdominal lipectomy in females does not affect significantly the components of metabolic syndrome and insulin sensitivity. Further high quality studies are needed to elucidate the potential metabolic effects of abdominal lipectomy. Systematic review registration PROSPERO CRD42015017564 (www.crd.york.ac.uk/PROSPERO).
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The relationship between epicardial fat and indices of obesity and the metabolic syndrome: a systematic review and meta-analysis.
Rabkin, SW
Metabolic syndrome and related disorders. 2014;(1):31-42
Abstract
Epicardial fat (epicardial adipose tissue, EAT) has been implicated in the pathogenesis of coronary artery disease (CAD). The objective of this study was to examine the relationship between EAT and generalized obesity, central or visceral adipose tissue (VAT), and the components of the metabolic syndrome--systolic blood pressure (SBP), triglycerides (TGs), high-density lipoprotein cholesterol (HDL-C), and fasting blood glucose (FBG)--that are linked to CAD. A systematic review of the literature, following meta-analysis guidelines, was conducted until May, 2013, using the search strategy "Obesity" OR "abdominal obesity" OR "metabolic syndrome" OR "metabolic syndrome X" AND "epicardial fat". Thirty-eight studies fulfilled the criteria. There was a highly significant (P<0.00001) correlation between EAT and body mass index (BMI), waist circumference (WC), or VAT. The correlation between EAT and VAT was significantly (P<0.0001) greater than the correlation between EAT and WC, which in turn was significantly greater than the correlation between EAT and BMI. Overall, EAT was 7.5 ± 0.1 mm in thickness in the metabolic syndrome (n=427) compared to 4.0 ± 0.1 mm in controls (n=301). EAT correlated significantly (P<0.0001) with SBP, TGs, HDL, and FBG, but the strength of the association was less than one-half of the relationship of EAT to indices of obesity. The results of multivariate analysis were less consistent but show a relationship between EAT and metabolic syndrome independent of BMI. In summary, the very strong correlation between EAT and VAT suggests a relationship between these two adipose tissue depots. Measurement of EAT can be useful to indicate VAT. Whereas EAT correlates significantly with each of the components of the metabolic syndrome- SBP, TGs, HDL, or FBG-the magnitude of the relationship is considerably and significantly less than the relationship of EAT to BMI. These data show the strong relationship between EAT and BMI but especially with WC and VAT. They also demonstrate the smaller magnitude of the association of EAT with standard coronary risk factors, related to the metabolic syndrome, and suggest that the unique features of this adipose tissue warrant detailed investigation.
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Abdominal adiposity distribution in diabetic/prediabetic and nondiabetic populations: a meta-analysis.
Lee, JJ, Beretvas, SN, Freeland-Graves, JH
Journal of obesity. 2014;:697264
Abstract
Excess fat in the abdomen can be classified generally as visceral and subcutaneous adiposity. Evidence suggests that visceral adiposity has greater implications for diabetes than other fat depots. The purpose of this study is to explore the disparities in the distribution of abdominal adiposity in diabetic/prediabetic and nondiabetic populations and to identify moderators that influence the pattern of central obesity via a meta-analysis technique. The Hedges' g was used as a measure of effect size and 95% confidence interval was computed. A total of 41 relevant studies with 101 effect sizes were retrieved. Pooled effect sizes for visceral and subcutaneous adiposity were 0.69 and 0.42, respectively. Diabetic/prediabetic populations exhibited greater visceral and subcutaneous adiposity compared to nondiabetic populations (Z = 10.35, P < 0.05). Significant moderator effects of gender (Z = -2.90) and assessment method of abdominal adiposity (Z = -2.17) were found for visceral fat (P < 0.05), but not for subcutaneous fat. Type of health condition influenced both visceral (Z = -5.10) and subcutaneous (Z = -7.09) abdominal adiposity volumes (P < 0.05). Abdominal adiposity distributions were significantly altered in the diabetic/prediabetic population compared to the nondiabetic population. Gender, assessment method of abdominal adiposity, and type of health conditions (diabetic/prediabetics) were identified as crucial moderators that influence the degree of abdominal adiposity.