Computed tomography-based assessment of abdominal adiposity changes and their impact on metabolic alterations following bariatric surgery

Body composition assessment in individuals with class II/III obesity: a narrative review

BACKGROUND

Individuals with class II/III obesity have a high percentage of body fat. Assessing body composition in cases of severe obesity can be difficult and controversial both in clinical practice and scientific research. Thus, it is essential to explore the different aspects of evaluating body composition and to discuss the available methods to assess it in this population.

AIMS

To summarise and discuss the methods used to measure body composition in adults with class II/III obesity and their potential in clinical practice and scientific research.

METHODS

This is a narrative review using data from PubMed, Scielo, and Lilacs databases. Original articles on body composition analysis in adults with class II/III obesity i.e., a BMI ≥ 35 kg/m2 were eligible. Body composition assessment methods were analysed and described.

RESULTS

Some imaging methods produced significantly accurate results. Dual-energy X-ray absorptiometry (DXA) significantly produces accurate results and has been used in clinical studies. However, due to its high cost, it is not applicable in clinical practice. Multifrequency bioelectrical impedance analysis (BIA) has good accuracy and is more appropriate for clinical practice than other methods. We have highlighted several aspects of the importance and applicability of performing body composition analysis in individuals with class II/III obesity.

CONCLUSION

DXA has been considered the most adequate method for clinical research. Multifrequency BIA may be a viable alternative to DXA for use in clinical practice. Assessing body composition and its components is important for people with class II/III obesity. It can help improve the effectiveness of interventions and clinical treatments, especially in reducing the risk of losing muscle mass. Muscle loss can cause sarcopenic obesity and other clinical complications, so understanding body composition is crucial. Assessing body composition can also help understand the impact of interventions on bones and avoid clinical complications.

The effect of bariatric surgery type on cardiac reverse remodelling

INTRODUCTION

Bariatric surgery is effective in reversing adverse cardiac remodelling in obesity. However, it is unclear whether the three commonly performed operations; Roux-en-Y Gastric Bypass (RYGB), Laparoscopic Sleeve Gastrectomy (LSG) and Laparoscopic Adjustable Gastric Band (LAGB) are equal in their ability to reverse remodelling.

METHODS

Fifty-eight patients underwent CMR to assess left ventricular mass (LVM), LV mass:volume ratio (LVMVR) and LV eccentricity index (LVei) before and after bariatric surgery (26 RYGB, 22 LSG and 10 LAGB), including 46 with short-term (median 251-273 days) and 43 with longer-term (median 983-1027 days) follow-up. Abdominal visceral adipose tissue (VAT) and epicardial adipose tissue (EAT) were also assessed.

RESULTS

All three procedures resulted in significant decreases in excess body weight (48-70%). Percentage change in VAT and EAT was significantly greater following RYGB and LSG compared to LAGB at both timepoints (VAT:RYGB -47% and -57%, LSG -47% and -54%, LAGB -31% and -25%; EAT:RYGB -13% and -14%, LSG -16% and -19%, LAGB -5% and -5%). Patients undergoing LAGB, whilst having reduced LVM (-1% and -4%), had a smaller decrease at both short (RYGB: -8%, p < 0.005; LSG: -11%, p < 0.0001) and long (RYGB: -12%, p = 0.009; LSG: -13%, p < 0.0001) term timepoints. There was a significant decrease in LVMVR at the long-term timepoint following both RYGB (-7%, p = 0.006) and LSG (-7%, p = 0.021), but not LAGB (-2%, p = 0.912). LVei appeared to decrease at the long-term timepoint in those undergoing RYGB (-3%, p = 0.063) and LSG (-4%, p = 0.015), but not in those undergoing LAGB (1%, p = 0.857). In all patients, the change in LVM correlated with change in VAT (r = 0.338, p = 0.0134), while the change in LVei correlated with change in EAT (r = 0.437, p = 0.001).

CONCLUSIONS

RYGB and LSG appear to result in greater decreases in visceral adiposity, and greater reverse LV remodelling with larger reductions in LVM, concentric remodelling and pericardial restraint than LAGB.

Short-Term Changes in Weight, Body Composition, and Metabolic Biomarkers After Laparoscopic Sleeve Gastrectomy in Patients with Obesity: A Comparative Prospective Study

PURPOSE

To investigate the changes in weight, body composition, and metabolic biomarkers in patients with obesity after laparoscopic sleeve gastrectomy (LSG) and compare those changes between patients with and without metabolic syndrome (MS).

MATERIALS AND METHODS

This retrospective longitudinal study included 76 patients who underwent LSG, among whom 32 had complete 1-year postoperative body composition and metabolic biomarkers. Body composition was measured by quantitative CT. Weight changes were compared between the MS and non-MS groups at 1-, 3-, 6-, and 12-month post-LSG in all patients; changes in body compositions and metabolic biomarkers from one day pre-LSG to 12-month post-LSG were also compared in those 32 patients.

RESULTS

MS occurred in 46% (35/76) of all patients and 44% (14/32) of patients with complete follow-up data. Excess weight loss was lower in the MS group than that in the non-MS group at 1-, 3-, 6-, and 12-month post-LSG; the 12-month difference was significant (MS vs. non-MS: 0.91 ± 0.22 vs. 1.07 ± 0.42, P = 0.04). The greatest rate of visceral fat area (VFA) change occurred 12-month post-LSG in both the non-MS [0.62(0.55,0.7)] and MS [0.6(0.51,0.63)] groups. The most significant reduction in ectopic fat occurred in liver fat (LF) [non-MS, 0.45(0.22,0.58); MS, 0.39(0.23,0.58)].

CONCLUSION

LGS significantly improves weight, body composition, and metabolic biomarkers in populations with obesity, regardless of whether they have MS. Among the body composition, VFA and LF were the most significantly improved body composition measurements.

Anthropometric Predictors of Health-Related Quality of Life in Obese Patients Attending a Tertiary Hospital in Nnewi, South-East Nigeria: A Cross-Sectional Study

BACKGROUND

Obesity as a disorder with excess body fat directly decreases quality of life. While Body Mass Index (BMI) has been used largely in health studies as a measure of obesity, it is largely unable to differentiate between body fat and lean body mass, hence other anthropometric measures can be used to assess body fat.

OBJECTIVE

To determine the association of anthropometric indicators with health-related quality of life (HRQoL) in obese adults.

MATERIALS AND METHODS

A cross-sectional study of obese adults (BMI ≥30kg/m2) attending the general outpatient clinic was conducted over four months. The quality of life was assessed using the short form-36 (SF-36) questionnaire. The anthropometric indicators used were BMI, waist circumference (WC), waist hip ratio (WHR), and waist-height ratio (WHtR).

RESULTS

Physical component summary (PCS) was significantly related to BMI, WHtR, and WC. After adjusting for co-variables (gender, age, occupation, and marital status), they remained significantly associated with PCS. Mental component summary (MCS) was significantly related to BMI, WHtR, and WC. After adjusting for the known determinants of HRQoL, only BMI remained significantly associated with MCS (P = -0.004; r = -0.146). When all the indicators were included in the same regression model, no anthropometric indicator was significantly related to MCS while only WHtR was significantly associated with PCS (P = 0.001; r = -0.465).

CONCLUSION

HRQoL in obese patients is related to measures of body fat. The physical and mental components of health-related quality of life are correlated differently with the various anthropometric measures of obesity. The WHtR was found to be an independent predictor of the physical component of HRQoL.

Mechanisms linking bariatric surgery to adipose tissue, glucose metabolism, fatty liver disease and gut microbiota

PURPOSE

In the last 20 years, bariatric surgery has achieved an important role in translational and clinical research because of obesity comorbidities. Initially, a tool to lose weight, bariatric surgery now has been shown to be involved in several metabolic pathways.

METHODS

We conducted a narrative review discussing the underlying mechanisms that could explain the impact of bariatric surgery and the relationship between obesity and adipose tissue, T2D, gut microbiota, and NAFLD.

RESULTS

Bariatric surgery has an impact in the relation between obesity and type 2 diabetes, but in addition  it induces the white-to-brown adipocyte trans-differentiation, by enhancing thermogenesis. Another issue is the connection of bariatric surgery with the gut microbiota and its role in the complex mechanism underlying weight gain.

CONCLUSION

Bariatric surgery modifies gut microbiota, and these modifications influence lipid metabolism, leading to improvement of non-alcoholic fatty liver disease.

Utility of Hypoglycemic Agents to Treat Asthma with Comorbid Obesity

Adults with obesity may develop asthma that is ineffectively controlled by inhaled corticosteroids and long-acting beta-adrenoceptor agonists. Mechanistic and translational studies suggest that metabolic dysregulation that occurs with obesity, particularly hyperglycemia and insulin resistance, contributes to altered immune cell function and low-grade systemic inflammation. Importantly, in these cases, the same proinflammatory cytokines believed to contribute to insulin resistance may also be responsible for airway remodeling and hyperresponsiveness. In the past decade, new research has emerged assessing whether hypoglycemic therapies impact comorbid asthma as reflected by the incidence of asthma, asthma-related emergency department visits, asthma-related hospitalizations, and asthma-related exacerbations. The purpose of this review article is to discuss the mechanism of action, preclinical data, and existing clinical studies regarding the efficacy and safety of hypoglycemic therapies for adults with obesity and comorbid asthma.

Improvement of Pancreatic Steatosis and Indices of Insulin Resistance After Metabolic Surgery

Purpose

Obesity is associated with fat accumulation in ectopic sites such as the pancreas, the so-called pancreatic steatosis (PS). Bariatric surgery has been shown to be associated with reducing pancreatic fat. This study investigated the effect of laparoscopic sleeve gastrectomy (LSG) on pancreatic volume and its fat content and glucose homeostasis.

Methods

The study enrolled 54 patients subjected to LSG. Metabolic variables and pancreatic exocrine function were assessed immediately before surgery and 12 months after. MRI of the abdomen was performed to measure pancreatic fat content and its total volume and visceral adipose tissue (VAT).

Results

Surgery resulted in a significant reduction in body weight and BMI. HbA1c, fasting insulin, C-peptide levels, HOMA-IR, and Hs-CRP levels decreased significantly. Surgery resulted in significant improvement in lipid profile except for HDL-cholesterol and liver function tests. Total VAT volume decreased significantly. Total pancreas volume decreased by a mean of 9.0 cm³ (95% CI: 6.6–11.3). The median change of pancreatic fat was −26.1% (range: −55.6 to 58.3%). Pancreatic lipase decreased significantly (P < 0.001). There was a positive correlation between the percentage of total weight loss and decrease in pancreatic fat volume (r = 0.295, P = 0.030).

Conclusion

Weight loss after LSG is associated with a reduction of total VAT volume, total pancreatic volume, and pancreatic fat content. These changes are associated with improved glucose homeostasis, reduced systemic inflammation, and decreased pancreatic lipase secretion.

Single-cell chromatin accessibility and lipid profiling reveals SCD1-dependent metabolic shift in adipocytes induced by bariatric surgery

Obesity promotes type 2 diabetes and cardiometabolic pathologies. Vertical sleeve gastrectomy (VSG) is used to treat obesity resulting in long-term weight loss and health improvements that precede weight loss; however, the mechanisms underlying the immediate benefits remain incompletely understood. Because adipose plays a crucial role in energy homeostasis and utilization, we hypothesized that VSG exerts its influences, in part, by modulating adipose functional states. We applied single-cell ATAC sequencing and lipid profiling to inguinal and epididymal adipose depots from mice that received sham surgery or VSG. We observed depot-specific cellular composition and chromatin accessibility patterns that were altered by VSG. Specifically, accessibility at Scd1, a fatty acid desaturase, was substantially reduced after VSG in mature adipocytes of inguinal but not epididymal depots. This was accompanied by reduced accumulation of SCD1-produced unsaturated fatty acids. Given these findings and reports that reductions in Scd1 attenuate obesity and insulin resistance our results suggest VSG exerts its beneficial effects through an inguinal depot-specific reduction of SCD1 activity.

Deciphering CT texture features of human visceral fat to evaluate metabolic disorders and surgery-induced weight loss effects

Background

Metabolic syndrome (MetS) is highly related to the excessive accumulation of visceral adipose tissue (VAT). Quantitative measurements of VAT are commonly applied in clinical practice for measurement of metabolic risks; however, it remains largely unknown whether the texture of VAT can evaluate visceral adiposity, stratify MetS and predict surgery-induced weight loss effects.

Methods

675 Chinese adult volunteers and 63 obese patients (with bariatric surgery) were enrolled. Texture features were extracted from VATs of the computed tomography (CT) scans and machine learning was applied to identify significant imaging biomarkers associated with metabolic-related traits.

Findings

Combined with sex, ten VAT texture features achieved areas under the curve (AUCs) of 0.872, 0.888, 0.961, and 0.947 for predicting the prevalence of insulin resistance, MetS, central obesity, and visceral obesity, respectively. A novel imaging biomarker, RunEntropy, was identified to be significantly associated with major metabolic outcomes and a 3.5-year follow-up in 338 volunteers demonstrated its long-term effectiveness. More importantly, the preoperative imaging biomarkers yielded high AUCs and accuracies for estimation of surgery responses, including the percentage of excess weight loss (%EWL) (0.867 and 74.6%), postoperative BMI group (0.930 and 76.1%), postoperative insulin resistance (0.947 and 88.9%), and excess visceral fat loss (the proportion of visceral fat reduced over 50%; 0.928 and 84.1%).

Interpretation

This study shows that the texture features of VAT have significant clinical implications in evaluating metabolic disorders and predicting surgery-induced weight loss effects.

Funding

The complete list of funders can be found in the Acknowledgement section.

Quality of life and its relationship with different anthropometric indicators in adults with obesity

Abtract Introduction: Obesity compromises the quality of life. However, few studies have investigated the influence of different anthropometric indicators on the quality of life of this population. Objective: We aimed to correlate the physical and mental components of quality of life and verify its association with different anthropometric indicators in adults with obesity. Methods: A cross-sectional study was conducted in adults with obesity [body mass index (BMI) ≥ 30 kg/m²]. The quality of life was investigated using the SF-36 questionnaire, with scores ranging from 0 (worst-case scenario) to 100 (best scenario for the outcome). The anthropometric indicators used were BMI, waist circumference, waist/height ratio (WHR), and lean and fat body mass. For analysis, Spearman’s correlation and crude and adjusted linear regression for sociodemographic variables were used. Results: A total of 75 subjects (nfemales = 47; µage= 34.8 ± 7.1 years) were included, and their means of the physical and mental components were 64.5 ± 15.9 and 50.8 ± 21.3 points, respectively. The social functioning domain presented a strong positive correlation (r = 0.760) with the mental health domain, and eight moderate correlations (0.400 ≤ r ≥ 0.699) were found between the different domains of the questionnaire. The functional capacity domain and the physical component presented a moderate negative correlation with the WHR (r = -0.402 and r = -0.407, respectively). After adjustment, the WHR was inversely associated with the physical component (β = -1.197; p = 0.002). Conclusion: In adults with obesity, important correlations were observed between the physical and mental components of quality of life, and the waist/height ratio was the only anthropometric indicator correlated and associated with the physical component of the outcome.

Associations of Visceral, Subcutaneous, Epicardial, and Liver Fat with Metabolic Disorders up to 14 Years After Weight Loss Surgery

Background: Bariatric surgery leads to long-term remission and reduced incidence of diabetes, hypertension, and dyslipidemia. Short-term studies suggest reduction in specific fat depots may be more predictive of health improvement than reduced body mass index (BMI). Visceral, subcutaneous, epicardial, and liver fat, measured 11 years after bariatric surgery, were associated with long-term remission and incidence of diabetes, dyslipidemia, and hypertension. Methods: Fat depots an average of 11 (maximum 14) years after surgery were quantified by noncontrast computed tomography in subjects who did (N = 261; 86% gastric bypass) or did not (N = 243) have bariatric surgery. Multiple regression related fat depots to disease endpoints with and without adjustment for change in BMI and surgical status. Results: Visceral fat was 42% lower, subcutaneous fat 20% lower, epicardial fat 30% lower, and liver-to-spleen density ratio 9% higher at follow-up in the bariatric surgery group compared with the nonsurgery group (all P < 0.01). Higher visceral fat at follow-up exam was significantly associated with reduced remission and increased incidence of diabetes, hypertension, and dyslipidemia. Subcutaneous fat was not associated with disease. The liver-to-spleen ratio was associated with the remission and incidence of hypertriglyceridemia and not with other fat depots. Epicardial fat was related to incidence of elevated low-density lipoprotein cholesterol and low high-density lipoprotein cholesterol. Conclusions: Whether or not a patient shows greater long-term diabetes, dyslipidemia, or hypertension remission or incidence after bariatric surgery appears dependent on the amount of fat within specific fat depots measured at follow-up. Furthermore, associations of the three disease endpoints with different fat depots suggest varied fat depot pathology.

Effect of Bariatric Surgery on Serum Inflammatory Factors of Obese Patients: a Systematic Review and Meta-Analysis

Obesity is one of the main causes of inflammation. Previous studies have reported inconclusive results regarding the effect of bariatric surgery on inflammatory markers. This systematic review and meta-analysis is aimed at describing the effect of bariatric surgery on C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α). PubMed/Medline and Scopus were systematically searched for all eligible studies from inception to June 2018. Results are expressed as weighted mean difference (MD) with 95% confidence intervals (CI) using a random effects model. Overall, 116 studies which evaluated serum CRP, IL-6, and TNF-α after bariatric surgery were included. Pooled effect size showed significant reduction in serum CRP (- 5.30 mg/l, 95% CI - 5.46, - 5.15, P < 0.001), IL-6 (- 0.58 pg/ml, 95% CI - 0.64, - 0.53, P < 0.001), and TNF-α (- 0.20 pg/ml, 95% CI - 0.39, - 0.02, P = 0.031) with significant heterogeneity across studies (> 95% for all factors). Bariatric surgery significantly lowered inflammatory factors; however, baseline BMI, follow-up duration and type of surgery could impact the extent of observed effects.

The impact of weight change on intra-abdominal and hernia volumes

BACKGROUND

Weight loss is often encouraged or required before open ventral hernia repair. This study evaluates the impact of weight change on total, intra-abdominal, subcutaneous, and hernia volume.

METHODS

Patients who underwent open ventral hernia repair from 2007 to 2018 with two preoperative computed tomography scans were identified. Scans were reviewed using 3D volumetric software. Demographics, operative characteristics, and outcomes were evaluated. The impact of weight change on intra-abdominal, subcutaneous, and hernia volume was assessed using Spearman's correlation coefficients and linear regression models.

RESULTS

A total of 250 patients met the criteria with a mean defect area of 155.6 ± 155.4 cm², subcutaneous volume of 6,800.0 ± 3,868.8 cm³, hernia volume of 915.7 ± 1,234.5 cm³, intra-abdominal volume equaling 4,250.2 ± 2,118.1 cm³, and time between computed tomography scans 13.9 ± 11.0 months. Weight change was associated with change in hernia, intra-abdominal, total, and subcutaneous volume (Spearman's correlation coefficients 0.17, 0.48, 0.51, 0.45, respectively, P ≤ 0.03 all values) and not associated in hernia length, width, or area (P ≥ 0.18 all values). A Δ5 kg was significantly associated with Δintra-abdominal volume (164.1 ± 30.0 cm³/Δ5 kg,P < .0001), Δtotal volume (209.9 ± 33.0 cm³/Δ5 kg, P < .0001), and Δsubcutaneous volume (234.4 ± 50.8 cm³/Δ5 kg, P < .0001). Per Δ5 kg, male patients had more than double the Δintra-abdominal, Δtotal, and Δsubcutaneous volume than did female patients. A weight change of 5 kg to10 kg was associated with approximately double the change in computed tomography parameters/Δ5 kg than any weight change after 10 kg. Regardless of weight change, all measured hernia parameters increased over time, with mean hernia volume of +40.6 ± 94.9 cm³/mo and area of +7.8 ± 13.3 cm²/mo (Spearman's correlation coefficient -0.03 to 0.07, P value 0.37-0.96).

CONCLUSION

Weight change is linearly correlated with intra-abdominal and subcutaneous fat gain or loss. Males show greater abdominal-related response to weight gain or loss. Hernia dimensions increase over time regardless of weight change.

Adipose Tissue Distribution, Inflammation and Its Metabolic Consequences, Including Diabetes and Cardiovascular Disease

Adipose tissue plays essential roles in maintaining lipid and glucose homeostasis. To date several types of adipose tissue have been identified, namely white, brown, and beige, that reside in various specific anatomical locations throughout the body. The cellular composition, secretome, and location of these adipose depots define their function in health and metabolic disease. In obesity, adipose tissue becomes dysfunctional, promoting a pro-inflammatory, hyperlipidemic and insulin resistant environment that contributes to type 2 diabetes mellitus (T2DM). Concurrently, similar features that result from adipose tissue dysfunction also promote cardiovascular disease (CVD) by mechanisms that can be augmented by T2DM. The mechanisms by which dysfunctional adipose tissue simultaneously promote T2DM and CVD, focusing on adipose tissue depot-specific adipokines, inflammatory profiles, and metabolism, will be the focus of this review. The impact that various T2DM and CVD treatment strategies have on adipose tissue function and body weight also will be discussed.

The clinical potential of circulating microRNAs in obesity

Obesity is a complex condition that is characterized by excessive fat accumulation, which can lead to the development of metabolic disorders, such as type 2 diabetes mellitus, nonalcoholic fatty liver disease and cardiovascular diseases. Evidence is accumulating that circulating microRNAs (miRNAs) act as a new class of endocrine factor. These miRNAs are released by many types of tissue, including adipose tissues. miRNAs might serve as endocrine and paracrine messengers that facilitate communication between donor cells and tissues with receptor cells or target tissues, thereby potentially having important roles in metabolic organ crosstalk. Moreover, many miRNAs are closely associated with the differentiation of adipocytes and are dysregulated in obesity. As such, circulating miRNAs are attractive potential biomarkers and hold promise for the development of miRNA-based therapeutics (such as miRNA mimetics, anti-miRNA oligonucleotides and exosomes loaded with miRNA) for obesity and related disorders. Here we review the latest research progress on the roles of circulating miRNAs in metabolic organ crosstalk. In addition, we discuss the clinical potential of circulating miRNAs as feasible biomarkers for the assessment of future risk of metabolic disorders and as therapeutic targets in obesity and related diseases.

Relationships between computed tomography-assessed density, abdominal fat volume, and glucose metabolism after sleeve gastrectomy in Japanese patients with obesity

In this study, we investigated the relationships between body weight (BW), computed tomography (CT)-assessed abdominal adipose tissue, and the glycemic metabolic profile in obese Japanese patients following laparoscopic sleeve gastrectomy (LSG). This study analyzed adipose tissue compartments using CT methods before and 1 year after LSG. Thirty obese patients were studied, and variables measured included visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), density of VAT (VAT-D), and density of SAT (SAT-D). We also examined the parameters in patients according to whether they had type-2 diabetes (T2DM). LSG induced significant losses in BW, SAT, and VAT after LSG. Additionally, SAT-D and VAT-D both increased and fasting plasma glucose (FPG) and HbA1c, but not C-peptide, decreased after surgery. ΔSAT and ΔVAT were positively related, and ΔSAT-D and ΔVAT-D were negatively related to ΔBW and/or FPG. Furthermore, a multivariate regression model showed that total BW loss (TBWL) was closely related to ΔSAT (β = 0.84; p < 0.001) and ΔVAT-D (β = -0.45; p < 0.05) and improvement of FPG was related to ΔVAT (β = 0.61; p < 0.05) after LSG. Finally, ΔFPG was correlated with ΔVAT in 16 T2DM patients (r = 0.58; p < 0.05) but not in non-T2DM patients. TBWL was related to ΔSAT and ΔVAT-D, and improvement of FPG was related to ΔVAT in obese Japanese patients after LSG.

Bariatric Surgery Alters microRNA Content of Circulating Exosomes in Patients with Obesity

OBJECTIVE

Exosomal microRNAs (miRNAs) are potential biomarkers for obesity, in which they regulate biological processes. Bariatric surgery has health benefits for patients with obesity; however, the mechanisms of these benefits are not clear. This study attempted to identify the exosomal miRNA signature associated with obesity and how it changed after bariatric surgery.

METHODS

Healthy volunteers (HVs) and nondiabetic patients with obesity were prospectively enrolled in the study. The study assessed the serum exosomal miRNA profiles of HVs and patients with obesity using RNA sequencing. To evaluate the effects of bariatric surgery, the study also analyzed exosomal miRNAs in patients 6 months after surgery.

RESULTS

RNA sequencing revealed differential expression of 72 exosomal miRNAs in patients with obesity compared with HVs and differential expression of 41 miRNAs in post- versus presurgery blood. Among the differentially expressed miRNAs, the study identified nine surgery-responsive miRNAs that were highly expressed in patients before surgery compared with HVs. Biological pathway analysis of the nine miRNAs indicated that they are likely involved in WNT, neurotrophin, and insulin signaling; the insulin receptor signaling cascade; and focal adhesion.

CONCLUSIONS

Patients with obesity have a distinct exosomal miRNA expression profile compared with HVs. In addition, weight loss after surgery alters the exosomal miRNA profile of patients with obesity.

Gut adaptation after metabolic surgery and its influences on the brain, liver and cancer

Metabolic surgery is the best treatment for long-term weight loss maintenance and comorbidity control. Metabolic operations were originally intended to change anatomy to alter behaviour, but we now understand that the anatomical changes can modulate physiology to change behaviour. They are no longer considered only mechanically restrictive and/or malabsorptive procedures; rather, they are considered metabolic procedures involving complex physiological changes, whereby gut adaptation influences signalling pathways in several other organs, including the liver and the brain, regulating hunger, satiation, satiety, body weight, glucose metabolism and immune functions. The integrative physiology of gut adaptation after these operations consists of a complex mechanistic web of communication between gut hormones, bile acids, gut microbiota, the brain and both enteric and central nervous systems. The understanding of nutrient sensing via enteroendocrine cells, the enteric nervous system, hypothalamic peptides and adipose tissue and of the role of inflammation has advanced our knowledge of this integrative physiology. In this Review, we focus on the adaptation of gut physiology to the anatomical alterations from Roux-en-Y gastric bypass and vertical sleeve gastrectomy and the influence of these procedures on food intake, weight loss, nonalcoholic fatty liver disease (NAFLD) and cancer. We also aim to demonstrate the underlying mechanisms that could explain how metabolic surgery could be used as a therapeutic option in NAFLD and certain obesity-related cancers.

Body fat mass and distribution as predictors of metabolic outcome and weight loss after Roux-en-Y gastric bypass

BACKGROUND

Bariatric surgery such as Roux-en-Y gastric bypass (RYGB) remains the most effective treatment of obesity and associated co-morbidities. Body fat distribution associates with metabolic function.

OBJECTIVE

To investigate if preoperative body fat mass and distribution measured by dual-energy x-ray absorptiometry (DXA) predict weight loss and metabolic outcome after RYGB, and to compare predictive value of DXA with simple anthropometric measures.

SETTING

Four Swedish hospitals within the Stockholm area.

METHODS

Two hundred fifteen women scheduled for RYGB were included. Evaluations before and 2 years after RYGB included determination of insulin sensitivity by the homeostatic model assessment of insulin resistance, blood pressure, plasma lipids, and anthropometric measures, such as waist-to-hip-ratio and fat percentage estimated by formula. Body fat mass and distribution were determined by DXA.

RESULTS

Follow-up rate was 77.2% (n = 166). All clinical, anthropometric, and DXA measures were improved/reduced postsurgery (all P<.0001). Android/gynoid fat mass ratio and waist-to-hip-ratio predicted improved homeostatic model assessment of insulin resistance (P = .0028 and .0014), independently of body mass index and age. Body fat percentage, measured by DXA or estimated by formula, predicted percent weight loss (P<.0001 and .0083). Body mass index predicted percent weight loss and percent excess body mass index lost (P = .0022 and<.0001). DXA and anthropometric measures performed equally as predictors, except for DXA measured fat percentage that was slightly better than formula estimated.

CONCLUSION

DXA provided predictive values similar to those by basic anthropometric measures, suggesting a limited additional value of preoperative DXA to predict metabolic improvement and weight loss after RYGB in women.

Bariatric Embolization of the Left Gastric Arteries for the Treatment of Obesity: 9-Month Data in 5 Patients

PURPOSE

The purpose of this study is to investigate the safety and 9-month effectiveness of transcatheter left gastric artery embolization (LGAE) for treating patients with obesity.

MATERIALS AND METHODS

The protocol of this study was approved by the Institutional Ethics Review Board. Five obese patients (3 men and 2 women) with mean weight of 102.0 ± 16.19 kg (range, 82.1-125.5 kg) and mean body mass index (BMI) of 38.1 kg/m² ± 3.8 (range, 32.9-42.4 kg/m²) underwent LGAE with polyvinyl alcohol (PVA) particles in diameter of 500-710 μm. The primary endpoint was the safety by grading the adverse events (AEs) according to the Common Terminology Criteria for Adverse Events (CTCAE v4.0) within 30 days after LGAE. The secondary endpoints were measured with serum ghrelin and leptin levels, body weight, waist circumference, waist-to-height ratio, and abdominal fat quantity on MRI at the day immediately before LGAE and every 3 months after LGAE.

RESULTS

LGAE was successfully performed in all patients. A superficial linear ulceration below the cardia was seen in 1 patient 3 days after LGAE and healed within 30 days. No other serious AEs (grade III or above) occurred. Average body weight loss at 3, 6, and 9 months was 8.28 ± 7.3 kg (p = 0.074), 10.42 ± 8.21 kg (p = 0.047), and 12.9 ± 14.66 kg (p = 0.121), respectively. The level of serum ghrelin decreased by 40.83% (p = 0.009), 31.94% (p = 0.107), and 24.82% (p = 0.151) at 3, 6, and 9 months after LGAE, respectively. There was minimal reduction of leptin levels at 3 and 6 months following LGAE (decreased by 0.26%, p = 0.929, and 4.33%, p = 0.427, respectively), but it declined obviously 9 months after LGAE (decreased by 11.22%, p = 0.295). Both waist circumference and waist-to-height ratio decreased after LGAE. MRI showed the area of subcutaneous adipose tissue decreased from the baseline of 400.90 ± 79.25 to 320.36 ± 68.06 cm² (decreased by 20.09%, p = 0.006) at 3 months, to 328.31 ± 52.67 cm² (decreased by 18.11%, p = 0.020) at 6 months, and to 286.40 ± 55.72 cm² (decreased by 28.52%, p = 0.101) at 9 months after LGAE, respectively. But the decrease of abdominal fat loss at 9 months after LGAE was largely due to the reduction in visceral adipose tissue.

CONCLUSIONS

Our study with 9-month data in 5 patients indicates that bariatric embolization of the LGA is a safe and may be a promising strategy to suppress the production of ghrelin and results in weight loss and abdominal fat reduction.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT02786108).

Treatment of Obesity: Weight Loss and Bariatric Surgery

This review focuses on the mechanisms underlying, and indications for, bariatric surgery in the reduction of cardiovascular disease (CVD), as well as other expected benefits of this intervention. The fundamental basis for bariatric surgery for the purpose of accomplishing weight loss is the determination that severe obesity is a disease associated with multiple adverse effects on health, which can be reversed or improved by successful weight loss in patients who have been unable to sustain weight loss by nonsurgical means. An explanation of possible indications for weight loss surgery as well as specific bariatric surgical procedures is presented, along with review of the safety literature of such procedures. Procedures that are less invasive or those that involve less gastrointestinal rearrangement accomplish considerably less weight loss but have substantially lower perioperative and longer-term risk. The ultimate benefit of weight reduction relates to the reduction of the comorbidities, quality of life, and all-cause mortality. With weight loss being the underlying justification for bariatric surgery in ameliorating CVD risk, current evidence-based research is discussed concerning body fat distribution, dyslipidemia, hypertension, diabetes mellitus, inflammation, obstructive sleep apnea, and others. The rationale for bariatric surgery reducing CVD events is discussed and juxtaposed with impacts on all-cause mortalities. Given the improvement of established obesity-related CVD risk factors after weight loss, it is reasonable to expect a reduction of CVD events and related mortality after weight loss in populations with obesity. The quality of the current evidence is reviewed, and future research opportunities and summaries are stated.

Does bariatric surgery improve adipose tissue function?

Bariatric surgery is currently the most effective treatment for obesity. Not only do these types of surgeries produce significant weight loss but also they improve insulin sensitivity and whole body metabolic function. The aim of this review is to explore how altered physiology of adipose tissue may contribute to the potent metabolic effects of some of these procedures. This includes specific effects on various fat depots, the function of individual adipocytes and the interaction between adipose tissue and other key metabolic tissues. Besides a dramatic loss of fat mass, bariatric surgery shifts the distribution of fat from visceral to the subcutaneous compartment favoring metabolic improvement. The sensitivity towards lipolysis controlled by insulin and catecholamines is improved, adipokine secretion is altered and local adipose inflammation as well as systemic inflammatory markers decreases. Some of these changes have been shown to be weight loss independent, and novel hypothesis for these effects includes include changes in bile acid metabolism, gut microbiota and central regulation of metabolism. In conclusion bariatric surgery is capable of improving aspects of adipose tissue function and do so in some cases in ways that are not entirely explained by the potent effect of surgery. © 2016 World Obesity.

Quantification of adipose volume reduction with a prospective study analyzing the application of external radiofrequency energy and high voltage ultrashort pulse duration electrical fields

To date, there have been no objective measurements of subcutaneous volume loss following treatments with a noninvasive radiofrequency (RF)-based device. Twenty female patients were treated with a suction-coupled bipolar RF device using external RF energy combined with pulsed electromagnetic RF energy for subcutaneous fat reduction. Parameters followed included weight, Vectra measurements of abdominal circumference and torso volume, and high-definition ultrasound measurements of fat thickness. Measurements were taken before treatment and three times following treatment. Analysis of the measured parameters showed that mean circumference reduction of 2.30 cm was noted at three months post-treatment. Independent volumetric analysis showed a mean subcutaneous volume reduction of 428 cc three months following RF treatment. High-resolution ultrasound fat thickness was reduced by a mean of 39.6% three months following the final BodyFX treatment. Independent and paired-sample t-tests showed a p value of < 0.05. Repeated measures of analysis of covariance (ANCOVA) adjusted for differences in age, as well as height and weight (proxy for body mass index) to minimize individual differences and control for extraneous variables that may affect the pre- and post-treatment results were analyzed. No confounding variables were found. All analyses were conducted using IBM SPSS 21.0.