Visceral Adipose Tissue Loss and Insulin Resistance 6 Months after Laparoscopic Gastric Banding Surgery: A Preliminary Study

Temporal Relationship Between Insulin Resistance and Lipid Accumulation After Bariatric Surgery: a Multicenter Cohort Study

PURPOSE

Insulin resistance (IR) is closely associated with lipid accumulation. Here, we investigated the temporal relationship between the two conditions after bariatric surgery.

MATERIALS AND METHODS

In total, 409 participants were enrolled from three bariatric centers in China from 2009 to 2018. We evaluated whether baseline IR (proxied by homeostasis model assessment of insulin resistance (HOMA-IR)) and lipid accumulation (proxied by visceral adiposity index (VAI) and lipid accumulation product (LAP)) were associated with follow-up IR and lipid accumulation (3 months postoperatively) using linear regression models. We then conducted a cross-lagged panel analysis model to simultaneously examine the bidirectional relationship between IR and lipid accumulation.

RESULTS

Multivariable linear regression analyses showed that baseline HOMA-IR was associated with follow-up VAI (β = 0.430, 95% CI: 0.082-0.778, p = 0.016) and LAP (β = 0.070, 95% CI: 0.010-0.130, p = 0.022). There was no relationship between baseline lipid accumulation and follow-up IR. Further cross-lagged panel analyses indicated that the path coefficient from baseline HOMA-IR to follow-up VAI (β₂ = 0.145, p = 0.003) was significantly greater than the coefficient from baseline VAI to follow-up HOMA-IR (β₁ =  - 0.013, p = 0.777). Similarly, the path coefficient from baseline HOMA-IR to follow-up LAP (β₂ = 0.141, p = 0.003) was significantly greater than the coefficient from baseline LAP to follow-up HOMA-IR (β₁ = 0.041, p = 0.391).

CONCLUSION

Our study demonstrated a unidirectional relationship from HOMA-IR to VAI and LAP, suggesting that the change in IR may precede lipid accumulation after surgery.

Excess body weight: Novel insights into its roles in obesity comorbidities

Excess body weight is a global health problem due to sedentary lifestyle and unhealthy diet, affecting 2 billion population worldwide. Obesity is a major risk factor for metabolic diseases. Notably, the metabolic risk of obesity largely depends on body weight distribution, of which visceral adipose tissues but not subcutaneous fats are closely associated with obesity comorbidities, including type 2 diabetes, non-alcoholic fatty liver disease, cardiovascular disease and certain types of cancer. Latest multi-omics and mechanistical studies reported the crucial involvement of genetic and epigenetic alterations, adipokines dysregulation, immunity changes, imbalance of white and brown adipose tissues, and gut microbial dysbiosis in mediating the pathogenic association between visceral adipose tissues and comorbidities. In this review, we explore the epidemiology of excess body weight and the up-to-date mechanism of how excess body weight and obesity lead to chronic complications. We also examine the utilization of visceral fat measurement as an accurate clinical parameter for risk assessment in healthy individuals and clinical outcome prediction in obese subjects. In addition, current approaches for the prevention and treatment of excess body weight and its related metabolic comorbidities are further discussed. DATA AVAILABILITY: No data was used for the research described in the article.

Change in Adipokines and Gastrointestinal Hormones After Bariatric Surgery: a Meta-analysis

PURPOSE

The study aimed to perform a meta-analysis about the change in adipokines and gastrointestinal hormones after bariatric surgery in patients with obesity.

MATERIALS AND METHODS

We searched the Cochrane Central Register of Controlled Trials, EMBASE, and PubMed for related articles and used Review Manager 5.4 for data aggregation. Sensitivity and subgroup analysis were also conducted when feasible.

RESULTS

As a result, 95 articles involving 6232 patients were included in the meta-analysis. After bariatric surgery, the levels of leptin, ghrelin, C-reactive protein (CRP), interleukin-6 (IL-6), high-sensitivity C-reactive protein (Hs-CRP), tumor necrosis, factor-α (TNF-α), and interleukin-1β (IL-1β) reduced, while adiponectin, glucagon-like peptide-1 (GLP-1), and peptide YY (PYY) levels increased significantly. Subgroup analysis indicated that there was a more significant reduction in leptin level with a longer follow-up time. OAGB had a greater effect on increasing adiponectin level compared with other procedures. SG procedure would bring about reduced ghrelin, while BPD resulted in increased ghrelin. Meta-regression analysis found that publication year, study design, number of patients, preoperative age, preoperative BMI, and quality assessment score were not significantly related to change in leptin, adiponectin, and ghrelin levels.

CONCLUSION

Bariatric surgery was associated with a significant decrease in leptin, ghrelin, CRP, IL-6, Hs-CRP, TNF-α, and IL-1β, as well as increase in adiponectin, GLP-1, and PYY levels.

Nonalcoholic Fatty Liver Disease: Current Global Burden

The map and global disease burden of chronic liver diseases are markedly changing, with nonalcoholic fatty liver disease (NAFLD) becoming the most common cause of liver diseases coinciding with the current epidemics of obesity, type 2 diabetes, and metabolic syndrome. Understanding the incidence and prevalence of NAFLD is critical because of its linkage to a significant economic burden of hospitalization and changing patterns in consequences, such as liver transplantation. Moreover, the long-term average health care expenses of NAFLD patients have exceeded those of other liver diseases. To lessen the imminent burden of NAFLD, immediate actions to raise worldwide awareness and address metabolic risk factors are required. This review summarizes key data about the global disease burden of NAFLD, modifiable and nonmodifiable risk factors, and current preventive approaches.

Circulating acyl and des-acyl ghrelin levels in obese adults: a systematic review and meta-analysis

Ghrelin is the only known orexigenic gut hormone, and its synthesis, secretion and degradation are affected by different metabolic statuses. This meta-analysis aimed to investigate the potential differences in plasma acyl ghrelin (AG) and des-acyl ghrelin (DAG) concentrations between normal weight and obese adults. Systematic literature searches of PubMed, Embase and Web of Science through October 2021 were conducted for articles reporting AG or DAG levels in obesity and normal weight, and 34 studies with 1863 participants who met the eligibility criteria were identified. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated to evaluate group differences in circulating AG and DAG levels. Pooled effect size showed significantly lower levels of baseline AG (SMD: - 0.85; 95% CI: - 1.13 to - 0.57; P_SMD < 0.001) and DAG (SMD: - 1.06; 95% CI: - 1.43 to - 0.69; P_SMD < 0.001) in obese groups compared with healthy controls, and similar results were observed when subgroup analyses were stratified by the assay technique or storage procedure. Postprandial AG levels in obese subjects were significantly lower than those in controls when stratified by different time points (SMD _30 min: - 0.85, 95% CI: - 1.18 to - 0.53, P_SMD < 0.001; SMD _60 min: - 1.00, 95% CI: - 1.37 to - 0.63, P_SMD < 0.001; SMD _120 min: - 1.21, 95% CI: - 1.59 to - 0.83, P_SMD < 0.001). In healthy subjects, a postprandial decline in AG was observed at 120 min (SMD: - 0.42; 95% CI: - 0.77 to - 0.06; P_SMD = 0.021) but not in obese subjects (SMD: - 0.28; 95% CI: - 0.60 to 0.03; P_SMD = 0.074). The mean change in AG concentration was similar in both the obese and lean health groups at each time point (ΔSMD_30min: 0.31, 95% CI: - 0.35 to 0.97, P_SMD = 0.359; ΔSMD_60min: 0.17, 95% CI: - 0.12 to 0.46, P_SMD = 0.246; ΔSMD_120min: 0.21, 95% CI: - 0.13 to 0.54, P_SMD = 0.224). This meta-analysis strengthens the clinical evidence supporting the following: lower baseline levels of circulating AG and DAG in obese individuals; declines in postprandial circulating AG levels, both for the healthy and obese individuals; a shorter duration of AG suppression in obese subjects after meal intake. These conclusions have significance for follow-up studies to elucidate the role of various ghrelin forms in energy homeostasis.

Improvement of glucose metabolism following rapid weight loss after bariatric surgery and its impact on reduction of visceral abdominal fat versus free fat muscle

BACKGROUND

Body fat distribution is highly associated with metabolic disturbances. Skeletal muscle plays an important role in glucose metabolism, as it serves as an important organ for glucose storage in the form of glycogen. In fact, low muscle mass has been associated with metabolic syndrome, type 2 diabetes (T2D), systemic inflammation, and decreased survival.

OBJECTIVES

To compare the relationship between visceral abdominal fat (VAF) and fat free mass (FFM) with the improved glucose metabolism after bariatric surgery.

SETTING

University hospital, United States.

METHODS

A retrospective review was performed of all patients who underwent bariatric surgery between 2011 and 2017 at a university hospital in the United States. In severely obese patients with T2D, we measured the VAF via abdominal computed tomography scan and we calculated the FFM preoperatively and at a 12-month follow-up. Data collected included baseline demographic characteristics and perioperative parameters, such as treatment for hypertension (HTN) and T2D, body mass index (BMI), glycated hemoglobin (HbA1C), glucose, and lipid profile.

RESULTS

A total of 25 patients met the inclusion criteria. The average age was 52.5 ± 11.6 years. The initial BMI was 41.41 ± 5.7 kg/m² and the postoperative BMI was 31.7 ± 6.9 kg/m² (P < .0001). The preoperative VAF volume was 184.6 ± 90.2 cm³ and the postoperative VAF volume was 93.8 ± 46.8 cm³ at the 12-month follow-up (P < .0001). The preoperative FFM was 55.2 ± 11.4 kg and the postoperative FFM was 49.1 ± 12 kg (P < .072). The preoperative HbA1C was 5.8% ± .9%, which decreased postoperatively to 5.3% ± .4% at the 12-month follow-up (P < .013).

CONCLUSION

Bariatric surgery has been demonstrated to be an effective treatment modality for severe obesity and T2D. Our results suggest that at 12 months, there is a reduction in VAF and HbA1C without a significant loss of FFM. Further prospective studies are needed to better understand these findings.

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 Exercise on NAFLD and Its Risk Factors: Comparison of Moderate versus Low Intensity Exercise

Background and Aims: Lifestyle (exercise and dietary) modification is the mainstay of treatment for non-alcoholic fatty liver disease (NAFLD). However, there is paucity of data on effect of intensity of exercise in management of NAFLD, and we aimed to study the effect of variable intensities of exercise on NAFLD. Methods: The study was performed in the Department of Gastroenterology of the SCB Medical College, Cuttack and the Biju Patnaik State Police Academy, Bhubaneswar. The subjects were police trainees [18 in a moderate intensity exercise group (MIG) and 19 in a low intensity exercise group (LIG)] recruited for a 6-month physical training course (261.8 Kcalorie, 3.6 metabolic equivalent in MIG and 153.6 Kcalorie, 2.1 metabolic equivalent in LIG). NAFLD was diagnosed by ultrasonography, with exclusion of all secondary causes of steatosis. All participants were evaluated by anthropometry (weight, height, body mass index (BMI), waist circumference), assessed for blood pressure and biochemical parameters (blood glucose, liver function test, lipid profile, serum insulin), and subjected to transabdominal ultrasonography before and after 6 months of physical training, and the results were compared. Results: Both the groups had similar BMI, fasting plasma glucose, AST, gamma-glutamyl transpeptidase, insulin, and homeostatic model assessment-insulin resistance (known as HOMA-IR) (p>0.05). However, subjects in the LIG were older and had lower alanine transaminase, higher triglycerides and lower high-density lipoproteins than MIG subjects. There was a significant reduction in BMI (27.0±2.1 to 26.8±2.0; p=0.001), fasting blood glucose (106.7±21.6 to 85.8±19.0; p<0.001), serum triglycerides (167.5±56.7 to 124.6±63.5; p=0.017), total cholesterol (216.8±29.2 to 196.7±26.6; p=0.037), low-density lipoprotein cholesterol (134.6±21.4 to 130.5±21.9; p=0.010), serum aspartate transaminase (39.3±32.2 to 30.9±11.4; p<0.001), serum alanine transaminase (56.6±28.7 to 33.0±11.3; p<0.001) and HOMA-IR (2.63±2.66 to 1.70±2.59; p<0.001) in the MIG. However, changes in these parameters in the LIG were non-significant. Hepatic steatosis regressed in 66.7% of the NAFLD subjects in the MIG but in only 26.3% of the LIG NAFLD subjects (p=0.030). Conclusions: Moderate rather than low intensity physical activity causes significant improvement in BMI, serum triglycerides, cholesterol, serum transaminases and HOMA-IR, and regression of ultrasonographic fatty change in liver among NAFLD subjects.

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.

Efficacy of a 2-Month Very Low-Calorie Ketogenic Diet (VLCKD) Compared to a Standard Low-Calorie Diet in Reducing Visceral and Liver Fat Accumulation in Patients With Obesity

Background: Currently the treatment of non-alcoholic fatty liver disease (NAFLD) is based on weight loss through lifestyle changes, such as exercise combined with calorie-restricted dieting. Objectives: To assess the effects of a commercially available weight loss program based on a very low-calorie ketogenic diet (VLCKD) on visceral adipose tissue (VAT) and liver fat content compared to a standard low-calorie (LC) diet. As a secondary aim, we evaluated the effect on liver stiffness measurements. Methods: Open, randomized controlled, prospective pilot study. Patients were randomized and treated either with an LC or a VLCKD and received orientation and encouragement to physical activity equally for both groups. VAT, liver fat fraction, and liver stiffness were measured at baseline and after 2 months of treatment using magnetic resonance imaging. Paired t-tests were used for comparison of continuous variables between visits and unpaired test between groups. Categorical variables were compared using the χ²-test. Pearson correlation was used to assess the association between VAT, anthropometric measures, and hepatic fat fraction. A significance level of the results was established at p < 0.05. Results: Thirty-nine patients (20 with VLCKD and 19 with LC) were evaluated at baseline and 2 months of intervention. Relative weight loss at 2 months was -9.59 ± 2.87% in the VLCKD group and -1.87 ± 2.4% in the LC group (p < 0.001). Mean reductions in VAT were -32.0 cm² for VLCKD group and -12.58 cm² for LC group (p < 0.05). Reductions in liver fat fraction were significantly more pronounced in the VLCKD group than in the LC group (4.77 vs. 0.79%; p < 0.005). Conclusion: Patients undergoing a VLCKD achieved superior weight loss, with significant VAT and liver fat fraction reductions when compared to the standard LC diet. The weight loss and rapid mobilization of liver fat demonstrated with VLCKD could serve as an effective alternative for the treatment of NAFLD. Clinical Trial Registration: ClinicalTrials.gov, identifier: NCT04322110.

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.

Comparative Effects of Medical Versus Surgical Weight Loss on Body Composition: a Pilot Randomized Trial

OBJECTIVE

Bariatric surgery leads to more rapid and greater weight loss (WL) compared to medical weight loss (MWL), but the differences in body composition (BC) changes for these modalities remain unclear. Due to the known health risks associated with central adiposity, we compared the changes in regional distribution of fat mass (FM) and lean mass (LM) after surgical versus MWL.

METHODS

In this 1:1:1 randomized trial among 15 persons with type 2 diabetes and body mass index (BMI) 30-39.9 kg/m², we compared changes in BC, by dual-energy X-ray absorptiometry and abdominal computerized tomography, at time of 10%WL or 9 months after intervention (whichever came first). Participants underwent MWL, adjustable gastric banding (AGB), or Roux-en-Y gastric bypass (RYGB). Non-parametric tests evaluated BC differences (FM, LM, and visceral adipose tissue [VAT]) within and across all three arms and between pair-wise comparisons.

RESULTS

Twelve female participants (75% African American) completed the study. Patient age, BMI, and baseline anthropometric characteristics were similar across study arms. AGB lost more LM (MWL - 5.2%, AGB - 10.3%, p = 0.021) and VAT (MWL + 10.9%, AGB - 28.0%, p = 0.049) than MWL. RYGB tended to lose more VAT (MWL +10.9%, RYGB - 20.2%, p = 0.077) than MWL. AGB tended to lose more LM than RYGB (AGB - 12.38%, RYGB - 7.29%, p = 0.15).

CONCLUSIONS

At similar WL, AGB lost more LM and VAT than MWL; RYGB similarly lost more VAT. Given the metabolic benefits of reducing VAT and retaining LM, larger studies should confirm the changes in BC after surgical versus medical WL.

CLINICAL TRIAL REGISTRATION

NCTDK089557 - ClinicalTrials.gov.

The role of visceral adipose tissue on improvement in insulin sensitivity following Roux-en-Y gastric bypass: a study in Chinese diabetic patients with mild and central obesity

Background

Most Chinese patients with type 2 diabetes mellitus (T2DM) have mild obesity and central obesity. Central obesity is combined with insulin resistance. The aim of this study was to assess the effect of abdominal adipose tissue on insulin-sensitivity improvement after Roux-en-Y gastric bypass (RYGB) in Chinese diabetic patients with mild and central obesity.

Methods

Seventeen T2DM patients with a mean body mass index of 30.3 kg/m² were scheduled for laparoscopic RYGB. A hyperinsulinemic-euglycemic clamp and dual-energy X-ray absorptiometry were performed prior to surgery and 3 months after RYGB. The primary end points were the correlations between insulin sensitivity and abdominal adipose tissue, including visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT), before and 3 months after RYGB.

Results

Indices of peripheral insulin sensitivity, including glucose-disposal rate (M value) and glucose infusion rate, were significantly increased after RYGB. Body-fat mass, VAT and SAT were significantly reduced after RYGB. The pre-operative M value was significantly correlated with VAT mass (r = –0.57, P = 0.02), but not correlated with SAT mass. M value changes after RYGB were highly correlated with changes in VAT mass (r = –0.59, P = 0.01), percentage of VAT mass (r = –0.66, P < 0.01), VAT area (r = –0.56, P = 0.02) and percentage of VAT area (r = –0.57, P = 0.02).

Conclusions

A significant correlation was observed between increased peripheral insulin sensitivity and decreased VAT following RYGB in Chinese patients with mild and central obesity. VAT and SAT were significantly decreased with improved insulin sensitivity after RYGB. VAT mass may be considered as an indication for gastric bypass during patient selection.

New obesity classification criteria as a tool for bariatric surgery indication

Obesity plays relevant pathophysiological role in the development of health problems, arising as result of complex interaction of genetic, nutritional, and metabolic factors. Due to the role of adipose tissue in lipid and glucose metabolism, and low grade inflammation, it is necessary to classify obesity on the basis of body fat composition and distribution, rather than the simply increase of body weight, and the Body Mass Index. The new term of adiposopathy (‘‘sick fat’’) clearly defines the pathogenic role of adipose tissue. Four phenotypes of obese individuals have been described: (1) normal weight obese (NWO); (2) metabolically obese normal weight; (3) metabolically healthy obese; and (4) metabolically unhealthy obese or “at risk” obese. Moreover, sarcopenic obesity has been related to all the phenotypes. The category of normal weight lean, represented by metabolically healthy normal weight has been classified to distinguish from NWO. It is crucial to recommend a bariatric surgery taking into account adiposopathy and sick fat that occurs with the expansion of fat mass, changing the inflammatory and metabolic profile of the patient. Body fat percentage and genetic polymorphism have to be evaluated to personalize the best bariatric surgery intervention.

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

BACKGROUND

The aim of this study was to evaluate the effects of surgically induced weight loss on the abdominal adipose tissue depots and the metabolic profile in morbidly obese (MO) patients.

METHODS

The study was performed with a semi-automated quantification of adipose tissue compartments on single-slice abdominal CT series before surgery, 6 and 12 months after bariatric surgery. Thirty-eight MO patients with mean age of 35.7 ± 10.1 years and mean body mass index (BMI) of 43.6 ± 6.5 kg/m(2) were studied (20 patients underwent gastric banding and 18 patients underwent sleeve gastrectomy). Anthropometric measurements, metabolic and inflammatory parameters were analyzed in each patient.

RESULTS

Markedly decreased levels of total abdominal adipose tissue, abdominal subcutaneous adipose tissue (AbSAT) and visceral adipose tissue (VAT) at 6 and 12 months were noted in comparison to the preoperative values. The total % reduction of VAT was significant higher in comparison to the total % reduction of AbSAT at 12 months after bariatric surgery (P < 0.01) with the mean ratio of AbSAT/VAT to increase from 4.1 ± 1.7 preoperatively to 6.2 ± 3.1 at 12 months postoperatively (P < 0.001). In addition, high-sensitivity C-reactive protein (hsCRP) decreased significantly with weight loss after bariatric surgery and the total abdominal lipid loss was related to the decrease in hsCRP.

CONCLUSIONS

Significant changes in abdominal lipid deposition occurred in MO patients 6 and 12 months after bariatric surgery. The changes were significantly, correlated with the magnitude of BMI loss. The fat redistribution may contribute to the improvements in metabolic abnormalities.

Imaging methods for analyzing body composition in human obesity and cardiometabolic disease

Advances in the technological qualities of imaging modalities for assessing human body composition have been stimulated by accumulating evidence that individual components of body composition have significant influences on chronic disease onset, disease progression, treatment response, and health outcomes. Importantly, imaging modalities have provided a systematic method for differentiating phenotypes of body composition that diverge from what is considered normal, that is, having low bone mass (osteopenia/osteoporosis), low muscle mass (sarcopenia), high fat mass (obesity), or high fat with low muscle mass (sarcopenic obesity). Moreover, advances over the past three decades in the sensitivity and quality of imaging not just to discern the amount and distribution of adipose and lean tissue but also to differentiate layers or depots within tissues and cells is enhancing our understanding of distinct mechanistic, metabolic, and functional roles of body composition within human phenotypes. In this review, we focus on advances in imaging technologies that show great promise for future investigation of human body composition and how they are being used to address the pandemic of obesity, metabolic syndrome, and diabetes.

Effect of bariatric surgery on humoral control of metabolic derangements in obese patients with type 2 diabetes mellitus: How it works

Obesity and diabetes is a co-pandemic and a major health concern that is expanding. It has many psychosocial and economic consequences due to morbidity and mortality of this disease combination. The pathophysiology of obesity and related diabetes is complex and multifactorial. One arm of this disease process is the genetic susceptibility. Other arm is dependent on the intricate neuro-humoral factors that converge in the central nerve system. Gut hormones and the adipose tissue derived factors plays an important role in this delicate network. Bariatric surgery provides the only durable option for treatment of obesity and furthermore it provides a remission in the concomitant diseases that accompany obesity. This review provides a brief insight to all these mechanisms and tries to deduce the possible reasons of remission of type 2 diabetes after bariatric surgery.

Continued loss in visceral and intermuscular adipose tissue in weight-stable women following bariatric surgery

OBJECTIVE

To assess changes in total (TAT), subcutaneous (SAT), visceral (VAT), and intermuscular (IMAT) adipose tissue by whole-body MRI before surgery and at 12 months and 24 months post-surgery in a subset of participants of the Longitudinal Assessment of Bariatric Surgery-2.

METHODS

From 0 to 12 months, n = 20 females and 3 males; from 12 to 24 months, n = 42 females and 7 males. Paired t-tests and GLM repeated measures examined changes in TAT, SAT, VAT, and IMAT at 12 and 24 months, with sex and age as covariates.

RESULTS

Changes from 0 to 12 months included weight (-41.9 ± 12.1 kg; -36%), TAT (-33.5 ± 9.6 kg; -56%), SAT (-29.2 ± 8.2 kg; -55%), VAT (-3.3 ± 1.6 kg; -73%), and IMAT (-0.99 ± 0.68 kg; -50%), all P < 0.001. In females, from 12 to 24 months, despite relative weight stability (-1.8 ± 6.5 kg, -2%; P = 0.085), VAT (-0.5 ± 0.7 kg; -30%; P < 0.001) and IMAT (-0.2 ± 0.4 kg; -14%; P = 0.012) decreased further. In males, from 12 to 24 months, weight increased (5.1 ± 5.2 kg; 6%; P = 0.04) with no significant changes in TAT or sub-depots.

CONCLUSIONS

Bariatric surgery continues to induce favorable changes in body composition, i.e., persistent adipose tissue loss at 24 months in the absence of further significant weight loss.

Could the improvement of obesity-related co-morbidities depend on modified gut hormones secretion?

Obesity and its associated diseases are a worldwide epidemic disease. Usual weight loss cures - as diets, physical activity, behavior therapy and pharmacotherapy - have been continuously implemented but still have relatively poor long-term success and mainly scarce adherence. Bariatric surgery is to date the most effective long term treatment for morbid obesity and it has been proven to reduce obesity-related co-morbidities, among them nonalcoholic fatty liver disease, and mortality. This article summarizes such variations in gut hormones following the current metabolic surgery procedures. The profile of gut hormonal changes after bariatric surgery represents a strategy for the individuation of the most performing surgical procedures to achieve clinical results. About this topic, experts suggest that the individuation of the crosslink among the gut hormones, microbiome, the obesity and the bariatric surgery could lead to new and more specific therapeutic interventions for severe obesity and its co-morbidities, also non surgical.

Development of minimally invasive techniques for management of medically-complicated obesity

The field of bariatric surgery has been rapidly growing and evolving over the past several decades. During the period that obesity has become a worldwide epidemic, new interventions have been developed to combat this complex disorder. The development of new laparoscopic and minimally invasive treatments for medically-complicated obesity has made it essential that gastrointestinal physicians obtain a thorough understanding of past developments and possible future directions in bariatrics. New laparoscopic advancements provide patients and practitioners with a variety of options that have an improved safety profile and better efficacy without open, invasive surgery. The mechanisms of weight loss after bariatric surgery are complex and may in part be related to altered release of regulatory peptide hormones from the gut. Endoscopic techniques designed to mimic the effects of bariatric surgery and endolumenal interventions performed entirely through the gastrointestinal tract offer potential advantages. Several of these new techniques have demonstrated promising, preliminary results. We outline herein historical and current trends in the development of bariatric surgery and its transition to safer and more minimally invasive procedures designed to induce weight loss.

Effects of changes in adipocyte hormones and visceral adipose tissue and the reduction of obesity-related comorbidities after laparoscopic sleeve gastrectomy in Japanese patients with severe obesity

The aim of this study was to evaluate the relative contribution of serum adipokines and adipokines from the patient's omentum-derived adipocytes (PODAs) and visceral adipose tissue (VAT) of Japanese patients with severe obesity. Secondarily, we analyzed patients' metabolic changes after laparoscopic sleeve gastrectomy (LSG). Twenty-three LSG patients and 23 non-obese patients undergoing elective abdominal surgery were enrolled. The levels of adipokines in the serum and the PODAs were measured. The clinical and metabolic data were evaluated at 6 months after LSG. The mean serum leptin levels and the mean serum plasminogen activator inhibitor type-1 (PAI-1) levels were significantly greater (p < 0.001) and the mean adiponectin levels were significantly lower in the LSG group (p = 0.006). In the measurements of the PODAs, the mean leptin levels (p < 0.001) were significantly greater and the mean adiponectin levels (p < 0.001) were significantly lower in the LSG group. The mean BMI (-12 kg/m², p < 0.001) and mean VAT (-135.5 cm², p = 0.001) were significantly decreased after LSG. In nine patients with type 2 diabetes mellitus, the reduction in VAT correlated with the change in high-sensitivity C-reactive protein (p = 0.006) and the homeostasis model of assessment of insulin resistance (p = 0.001). After 6 months, LSG markedly improved most obesity-related comorbidities. Our results suggest that LSG may contribute to VAT reduction, improved adipocyte hormone levels, and changes in gut physiology and endocrinology.

The role of hormonal factors in weight loss and recidivism after bariatric surgery

Substantial heterogeneity exists in weight loss trajectories amongst patients following bariatric surgery. Hormonal factors are postulated to be amongst the contributors to the variation seen. Several hormones involved in hunger, satiety, and energy balance are affected by bariatric surgery, with the alteration in hormonal milieu varying by procedure. Limited research has been conducted to examine potential hormonal mediators of weight loss failure or recidivism following bariatric surgery. While hormonal factors that influence weight loss success following gastric banding have not been identified, data suggest that hormonal factors may be involved in modulating weight loss success following gastric bypass. There may be hormonal mediators involved in determining the weight trajectory following sleeve gastrectomy, though the extremely limited data currently available prohibits definitive conclusions from being drawn. There is great need for future research studies to explore this knowledge gap, as improving this knowledge base could be of benefit to guide clinicians toward understanding the hormonal contributors to a patient's postoperative weight loss failure or recidivism or perhaps be of value in selecting the most appropriate bariatric procedure based on the preoperative hormone milieu. Integrative interdisciplinary approaches exploring these complex interrelationships could potentially increase the explanatory power of such investigations.

Relative contributions of afferent vagal fibers to resistance to diet-induced obesity

BACKGROUND

We previously demonstrated vagal neural pathways, specifically subdiaphragmatic afferent fibers, regulate expression of the intestinal sodium-glucose cotransporter SGLT1, the intestinal transporter responsible for absorption of dietary glucose. We hypothesized targeting this pathway could be a novel therapy for obesity. We therefore tested the impact of disrupting vagal signaling by total vagotomy or selective vagal de-afferentation on weight gain and fat content in diet-induced obese rats.

METHODS

Male Sprague-Dawley rats (n = 5-8) underwent truncal vagotomy, selective vagal de-afferentation with capsaicin, or sham procedure. Animals were maintained for 11 months on a high-caloric Western diet. Abdominal visceral fat content was assessed by magnetic resonance imaging together with weight of fat pads at harvest. Glucose homeostasis was assessed by fasting blood glucose and HbA1C. Jejunal SGLT1 gene expression was assessed by qPCR and immunoblotting and function by glucose uptake in everted jejunal sleeves.

RESULTS

At 11-months, vagotomized rats weighed 19% less (P = 0.003) and de-afferented rats 7% less (P = 0.19) than shams. Vagotomized and de-afferented animals had 52% (P < 0.0001) and 18% reduction (P = 0.039) in visceral abdominal fat, respectively. There were no changes in blood glucose or glycemic indexes. SGLT1 mRNA, protein and function were unchanged across all cohorts at 11-months postoperatively.

CONCLUSIONS

Truncal vagotomy led to significant reductions in both diet-induced weight gain and visceral abdominal fat deposition. Vagal de-afferentation led to a more modest, but clinically and statistically significant, reduction in visceral abdominal fat. As increased visceral abdominal fat is associated with excess morbidity and mortality, vagal de-afferentation may be a useful adjunct in bariatric surgery.

Insulin resistance and bariatric surgery

The objective of this article is to systematically review the changes in insulin resistance after various types of bariatric surgical procedures. A Pubmed and EMBASE search for studies measuring insulin resistance before and after bariatric surgery was done and all original research articles from 1980 to present (2011) were included. Only the currently widely performed bariatric procedures were included. A meta-analysis of change in HOMA-IR was conducted, grouping studies with similar duration of follow-up. The percentage decrease in HOMA-IR at <=2 weeks, 1 month, 3 months, 6 months, 12 months and >16-18 months was found to be (mean ± standard error) -33.48 ± 5.78, -46.43 ± 6.99, -38.79 ± 9.64, -58.62 ± 7.38, -44.91 ± 7.98 and -67.04 ± 10.78%, respectively. RYGB (gastric bypass) and BPD (biliopancreatic diversion) produced a significant decrease in insulin resistance at 2 weeks after surgery, while LSG (sleeve gastrectomy) was strongly trending. LSG produced an earlier decrease in insulin resistance when compared to LAGB (gastric banding). RYGB, BPD and LSG produce an early decrease in insulin resistance through yet unknown mechanisms.

Mechanisms responsible for excess weight loss after bariatric surgery

Obesity has increased alarmingly in the United States and is increasing in many countries of the world. Because obesity is an important risk factor for type 2 diabetes and other chronic diseases, it is important to develop approaches to counter the rapid increase in adiposity. One approach is bariatric surgery, the most successful clinical intervention known for treating obesity. Surgery can result in impressive weight loss and improvement of obesity-related comorbidities. Yet the mechanisms responsible for this remarkable effect of surgery remain controversial. It is now clear that caloric restriction, per se, does not explain all the reduction in stored fat mass after surgery. A number of gastrointestinal hormones, including glucagon-like peptide (GLP)-1, peptide YY, oxyntomodulin, GLP-2, glucose-dependent insulinotropic polypeptide, ghrelin, and others, can play roles in energy homeostasis and could be involved in bariatric-surgery-related weight loss and weight loss maintenance. Vagal innervation may play a role. In addition, there may be other yet-uncharacterized factors that could participate. This review discusses the possible roles of these hormonal mechanisms in various types of bariatric surgery to help elucidate some of the potential mechanisms at play in short-term and long-term post-bariatric surgery weight loss. Understanding such mechanisms could lead to new and efficacious means to control or even reduce the epidemic of obesity.

Editorial: Exercise for NAFLD: does intensity matter?

Currently, there are no established means for the prevention or treatment of non-alcoholic steatohepatitis (NASH) despite our increasing understanding of nonalcoholic fatty liver disease (NAFLD) pathogenesis implicating insulin resistance (IR) as a key factor and highlighting the central role of lipotoxic liver injury in the development of NASH. Lifestyle interventions aiming at decreasing IR and preventing lipotoxicity, including weight loss, diet, and physical exercise, are in the frontline for NASH patient management. Physical activity may ameliorate IR, maintain weight loss, and improve liver histology in NASH patients. However, there are no recognized criteria for the optimal intensity, duration, or total volume of exercise needed to obtain these beneficial effects. In this issue of the American Journal of Gastroenterology, Kistler and colleagues show that vigorous, but not moderate exercise, nor total duration or volume of physical activity, is related to decreased odds of having NASH or advanced fibrosis. Prospective studies using the objective criteria of physical activity, addressing the role of concurrent weight loss, and assessing individual histological features are needed to further clarify the effects of exercise intensity on NAFLD histology.

Individual variation in the (patho)physiology of energy balance

There are large individual differences in the susceptibility for metabolic disorders such as obesity, the metabolic syndrome and type 2 diabetes. Unfortunately, most animal studies in this field ignore the importance of individual variation which limits the face validity of these studies for translation to the human situation. We have performed a series of studies that were particularly focused on the individual differences in the (patho)physiology of energy balance. The studies were performed with passive and proactive individuals of two different rat strains: the Roman High and Low Avoidance rats and the Wild type Groningen rat. The data reveal that passive and proactive individuals differ significantly on several parameters, i.e. body composition, Hypothalamic-Pituitary-Adrenal (HPA) axis activity, plasma levels of insulin and leptin, intestinal transit time, systolic blood pressure and meal patterns. We also found that the selection line of the Roman Low Avoidance rat may be considered as a non-obese animal model for the metabolic syndrome, since these rats display, under sedentary conditions, many of the related symptoms such as hypertension, visceral adiposity and insulin resistance during an intravenous glucose tolerance test. These symptoms disappeared when the animals were allowed to exercise voluntarily in a running wheel. We conclude that experiments with passive and proactive individuals are highly relevant for studying the (patho)physiology and behavior of energy balance and the related metabolic disorders.

Visceral Adiposity, Insulin Resistance, and Type 2 Diabetes

The worldwide prevalence of obesity and obesity-related diseases continues to rise. Insulin resistance, the metabolic syndrome, and type 2 diabetes are all associated with obesity. Visceral fat is now recognized to have metabolic, endocrine, and immune functions; increased visceral adiposity enhances the risk of metabolic and cardiovascular disorders. Potential mechanisms of this increased risk may include increased free fatty acid release and alterations in adipokines. Lifestyle interventions resulting in weight loss and loss of visceral fat can have a significant impact on cardiometabolic risk. Bariatric surgery has also been shown to improve insulin resistance, type 2 diabetes, and other comorbidities of obesity. Several medical therapies for type 2 diabetes or obesity also show promise for an impact on visceral adiposity-related comorbidities.

Bariatric surgery and the gut-brain communication--the state of the art three years later

OBJECTIVE

This review analyzes the literature concerning gut peptides and bariatric surgery, from 2005 to July 2009. In particular, we are interested in whether, and how, gastrointestinal peptide alterations following surgery interfere with appetite/satiety, and what role they might play in the resolution of comorbidities.

RESEARCH METHODS AND PROCEDURE

PubMed/MEDLINE and ISI Web of Knowledge were used to search for human studies concerning gut peptides profiles after any bariatric operation technique.

RESULTS

Most of the studies reviewed had longitudinal design, short follow-up, and low statistical power. The diversity of study results may be partially explained by methodological aspects. Glucagon-like peptide-1, gastric inhibitory peptide, and peptide YY alterations may contribute to the excellent results in glycemic control of diabetics. Results do vary depending on bariatric operation technique; this is particularly evident in the case of ghrelin, which has been much studied in recent years. Ghrelin suppression has been linked to increased satiety, alterations in energy homeostasis, and better glucose metabolism.

CONCLUSIONS

There is a lack of long-term data on gastrointestinal hormone profiles after bariatric surgery and the studies have many methodological pitfalls. We still need prospective, long-term, good methodological studies in this area.

Coping style predicts the (in)sensitivity for developing hyperinsulinemia on a high fat diet in rats

The aim of this study was to explore interactions between coping style and diet as risk factors for developing insulin resistance in rats. We hypothesized that rats characterized by a passive coping strategy are more susceptible for developing insulin resistance and visceral obesity than proactively coping rats, particularly on a high (45%) fat diet. This hypothesis was tested by comparing 1) insulin and glucose responses to an intravenous glucose tolerance test (IVGTT), and 2) body fat distribution, in two rat models for passive and proactive coping styles. We found that the most extremely passive rats are characterized by elevated insulin levels during a IVGTT, even on chow. Moderately passive rats display normal insulin responses under chow conditions, but develop insulin resistance on a high fat diet. Proactive rats are remarkably resistant to insulin resistance and visceral obesity, even when overfeeding on a high fat diet. Carcass analysis revealed that passive rats are characterized by increased epididymal fat deposition, which is in line with the observed differences in insulin resistance. We conclude that a passive personality is prone to develop insulin resistance and visceral obesity on a palatable fat diet and a proactive personality might be protected against the development of diet-induced insulin resistance.

Effects of lifestyle measures, antiobesity agents, and bariatric surgery on serological markers of inflammation in obese patients

Overweight and obesity are highly prevalent in developed countries and are also becoming more frequent in the developing world. Overweight and obese patients have elevated levels of several inflammatory markers and this inflammatory state might contribute to their increased vascular risk. We summarize the effects of lifestyle changes, antiobesity agents, and bariatric surgery on serological inflammatory markers in overweight and obese patients. Most studies showed a decrease in inflammation with all 3 interventions. However, it remains to be established whether the decrease in inflammatory markers induced by lifestyle changes or (where indicated) with antiobesity agents or bariatric surgery will translate into reduced vascular morbidity and mortality in overweight and obese patients.