Early weight regain after gastric bypass does not affect insulin sensitivity but is associated with elevated ghrelin

Pharmacological treatment of non-responders following bariatric surgery

Obesity is a complex chronic disease and requires a long-term multidisciplinary management. Even patients undergoing bariatric surgery, one the most effective treatments for obesity, can have insufficient weight loss (IWL) than expected (primary non responder) or weight regain (WR) after a successful primary procedure (secondary non responder). A poor response represents a challenge of bariatric surgery that can induce persistence or recurrence of obesity-related comorbidities, prejudicing benefits of surgery. Increasing evidence suggests that weight loss medications represent a useful strategy in obesity care also after bariatric surgery procedures. This narrative review summarizes the evidence concerning anti-obesity therapy in the management of no-responders to primary bariatric surgery. Available data on liraglutide (one randomized double-blind placebo-controlled trial, three prospective and three retrospective studies), naltrexone/bupropion (three retrospective studies), orlistat (one case control prospective and one retrospective studies) and topiramate and phentermine (five retrospective studies) have been considered. Available data suggest that weight loss medications could offer a significant adjunctive benefit to lifestyle and behavioral modifications in the life-long management of obesity. Newer treatment modalities including the use of anti-obesity drugs provide patients and healthcare providers with more options in the management of poor response after bariatric surgery.

Weight Regain after Metabolic Surgery: Beyond the Surgical Failure

Patients undergoing metabolic surgery have factors ranging from anatomo-surgical, endocrine metabolic, eating patterns and physical activity, mental health and psychological factors. Some of the latter can explain the possible pathophysiological neuroendocrine, metabolic, and adaptive mechanisms that cause the high prevalence of weight regain in postbariatric patients. Even metabolic surgery has proven to be effective in reducing excess weight in patients with obesity; some of them regain weight after this intervention. In this vein, several studies have been conducted to search factors and mechanisms involved in weight regain, to stablish strategies to manage this complication by combining metabolic surgery with either lifestyle changes, behavioral therapies, pharmacotherapy, endoscopic interventions, or finally, surgical revision. The aim of this revision is to describe certain aspects and mechanisms behind weight regain after metabolic surgery, along with preventive and therapeutic strategies for this complication.

Weight loss trend after bariatric surgery in a population of obese patients

BACKGROUND AND AIMS

Bariatric Surgery (BS) is a therapeutic option in patients with severe obesity whose non-surgical techniques have failed. No work has previously explored trajectories of weight loss and how long this was maintained. Aim of study is to describe effect of BS and nutritional intervention on body weight trend in patients with obesity.

METHODS

792 patients who underwent BS from 1996 to 2021 were included. The Protocol provides Laparoscopic Sleeve Gastrectomy (LSG), Vertical Gastroplasty (VBG) and Roux-en-Y Gastric Bypass (GB). %Total Weight Loss (%TWL) and %Excess Weight Loss (%EWL) were evaluated in three cohort of patients. Cumulative incidence of clinical goal after surgery was calculated at two and five years after BS.

RESULTS

At two years of follow-up, average %TWL and %EWL were 31.2% (95% CI = 29.0-33.4%) and 71% (95% CI = 65.4-76.5%) for VBG, 34.7% (95% CI = 33.8-35.6%) and 78.0% (95% CI = 75.9-89.1%) for GB and 33.8% (95% CI = 32.5-35.1%) and 68.8% (95% CI = 66.1-71.6%) for LSG. At two years from surgery the cumulative incidence of clinical goal was 70.7% (95% CI = 59.1-79.1%) for VBG, 86.4% (95% CI = 82.4-89.6%) for GB and 83.4% (95% CI = 76.0-87.1%) for LSG. At five years from surgery, average % TWL and % EWL were 22.5% (95% CI = 10.2-34.8%) and 58.2% (95% CI = 28.4-88.1%) for VBG, 31.8% (95% CI = 30.2-33.3%) and 70.8% (95% CI = 67.5-74.1%) for GB and 29.5% (95% CI = 26.2-32.8%) and 62.0% (95% CI = 53.4-70.6%) for LSG respectively. At five years after having reached clinical goal the share of people who were able to maintain their weight was 49.5% (95% CI = 30.8-79.6%) for VBG, 69.5% (95% CI = 58.3-82.8%) for GB and 55.9% (95% CI = 42.1-74.3%) for LSG. The median time of clinical goal maintaining was 4.8 years for VBG (95% CI lower limit = 4.1), 6.6 years for GB (95% CI lower limit = 6.2) and 5.3 years for LSG (95% CI lower limit = 4.8).

CONCLUSIONS

Our work confirm effectiveness of BS in patients with obesity and show that who do not reach clinical goal within 2 years, hardly will reach it later and suggest necessity for a medium and long-term follow-up to prevent weight regain.

Weight Regain After Bariatric Surgery: Scope of the Problem, Causes, Prevention, and Treatment

PURPOSE OF REVIEW

Although bariatric surgery is the most effective treatment of severe obesity, a proportion of patients experience clinically significant weight regain (WR) with further out from surgery. The purpose of this review is to summarize the prevalence, predictors, and causes of weight regain.

RECENT FINDINGS

Estimating the prevalence of WR is limited by a lack of consensus on its definition. While anatomic failures such as dilated gastric fundus after sleeve gastrectomy and gastro-gastric fistula after Roux-en-Y gastric bypass can lead to WR, the most common causes appear to be dysregulated/maladaptive eating behaviors, lifestyle factors, and physiological compensatory mechanisms. To date, dietary, supportive, behavioral, and exercise interventions have not demonstrated a clinically meaningful impact on WR, and there is limited evidence for pharmacotherapy. Future studies should be aimed at better defining WR to begin to understand the etiologies. Additionally, there is a need for non-surgical interventions with demonstrated efficacy in rigorous randomized controlled trials for the prevention and reversal of WR after bariatric surgery.

Mucosal and hormonal adaptations after Roux-en-Y gastric bypass

The aim of this study was to perform a comprehensive literature review regarding the relevant hormonal and histologic changes observed after Roux-en-Y gastric bypass (RYGB). We aimed to describe the relevant hormonal (glucagon-like peptides 1 and 2 [GLP-1 and GLP-2], peptide YY [PYY], oxyntomodulin [OXM], bile acids [BA], cholecystokinin [CCK], ghrelin, glucagon, gastric inhibitory polypeptide [GIP], and amylin) profiles, as well as the histologic (mucosal cellular) adaptations happening after patients undergo RYGB. Our review compiles the current evidence and furthers the understanding of the rationale behind the food intake regulatory adaptations occurring after RYGB surgery. We identify gaps in the literature where the potential for future investigations and therapeutics may lie. We performed a comprehensive database search without language restrictions looking for RYGB bariatric surgery outcomes in patients with pre- and postoperative blood work hormonal profiling and/or gut mucosal biopsies. We gathered the relevant study results and describe them in this review. Where human findings were lacking, we included animal model studies. The amalgamation of physiologic, metabolic, and cellular adaptations following RYGB is yet to be fully characterized. This constitutes a fundamental aspiration for enhancing and individualizing obesity therapy.

Appetite Changes in Weight Regain and Weight Maintenance After Roux-en-Y Gastric Bypass

PURPOSE

Roux-en-Y gastric bypass (RYGB) surgery produces significant weight loss. However, a number of patients experience weight regain years after surgery. Factors driving weight regain after surgical interventions are currently being explored. Our objective was to investigate appetite-related measures associated with weight regain after RYGB surgery.

MATERIALS AND METHODS

Using a cross-sectional design, 29 participants (49.6 ± 9.1 years of age; current BMI 32.4 ± 4.7 kg/m², 43.6 ± 8.9 months post-RYGB) were stratified into tertiles according to weight regain per month after nadir (weight maintenance (WM), n = 9; low weight regain (LWR), n = 10; and high weight regain (HWR), n = 10). The average weight regain was, by design, significantly different between the groups (WM = 2.2 ± 2.5 kg; LWR = 10.0 ± 3.4 kg; HWR = 14.9 ± 6.3 kg regained, p < 0.05). Appetite (visual analog scales), olfactory performance ("sniffin sticks"), eating behaviors (Three Factor Eating Questionnaire), food reward (Leeds Food Preference Questionnaire), and appetite-related hormones (ghrelin, PYY, GLP-1 and leptin) were measured fasting and in response to a standardized test meal.

RESULTS

Dietary restraint was significantly higher than clinical cutoffs in WM and LWR (p < 0.05). As expected, significant time effects were noted for ghrelin, PYY, and GLP-1, but there were no group differences.

CONCLUSION

The results suggest that appetite-related outcomes are similar across individuals who have maintained weight loss and experienced regain following RYGB.

Metabolic profiles, energy expenditures, and body compositions of the weight regain versus sustained weight loss patients who underwent Roux-en-Y gastric bypass

BACKGROUND

Weight regain (WR) has been an emerging problem after Roux-en Y gastric bypass (RYGB) and little is known about the mechanisms of WR after RYGB.

OBJECTIVE

To evaluate the mechanisms of WR after RYGB through the postprandial gut hormones response, particularly glucagon-like peptide-1 (GLP-1), which regulates appetite control, energy expenditure, body composition, physical activities, dietary intake, and psychological factors.

SETTING

Duke University Medical Center, Durham, North Carolina.

METHODS

A cross sectional study of 34 patients who underwent RYGB at least 2 years and achieved ≥50% of excess weight loss at 1year was conducted. The subjects were categorized into WR group or sustained weight loss group, based upon whether their WR was ≥15% of postoperative lowest weight.

RESULTS

The WR group had less augmented postprandial GLP-1 response but exaggerated hyperinsulinemia. Postprandial peptide YY, ghrelin, and glucose were not different between group. Patients who regained weight required less weight-adjusted energy expenditure and had more percentage body fat and less percentage lean mass. The caloric intake and diet composition were comparable between groups; however, the WR group had higher depression scores, binge eating scales, and hunger rating and spent significantly less time on vigorous exercise.

CONCLUSIONS

The mechanisms of WR in patients who were initially successful after RYGB are complex and involved not only the role of postprandial gut hormone response but are also related to energy expenditure adaptation and body composition changes. Moreover, food preference and physical activity may play roles in weight control after bariatric surgery. Further prospective controlled trial is needed to explore the mechanisms of WR.

Weight Regain and Insufficient Weight Loss After Bariatric Surgery: Definitions, Prevalence, Mechanisms, Predictors, Prevention and Management Strategies, and Knowledge Gaps-a Scoping Review

Some patients experience weight regain (WR) or insufficient weight loss (IWL) after bariatric surgery (BS). We undertook a scoping review of WR and IWL after BS. We searched electronic databases for studies addressing the definitions, prevalence, mechanisms, clinical significance, preoperative predictors, and preventive and treatment approaches including behavioral, pharmacological, and surgical management strategies of WR and IWL. Many definitions exist for WR, less so for IWL, resulting in inconsistencies in the reported prevalence of these two conditions. Mechanisms and preoperative predictors contributing to WR are complex and multifactorial. A range of the current knowledge gaps are identified and questions that need to be addressed are outlined. Therefore, there is an urgent need to address these knowledge gaps for a better evidence base that would guide patient counseling, selection, and lead to improved outcomes.

Travel distance reduces follow-up compliance but has no effect on long-term weight loss success in bariatric patients

BACKGROUND

Patients seeking bariatric surgery are traveling longer distances to reach Bariatric Centers. The purpose of this study was to evaluate the impact of travel distance on adherence to follow-up and outcomes after bariatric surgery.

METHODS

A retrospective review of all consecutive patients who had undergone bariatric surgery from June 2013 to May 2014 was performed, and the patients were divided into two groups: those who traveled 50 miles or less and those who traveled more than 50 miles. Primary outcome assessed was the influence of distance on post-operative follow-up attrition over 4-year period. Secondary outcomes assessed were excess weight loss, length of stay (LOS), complications and readmission rates.

RESULTS

A total of 228 patients underwent bariatric surgery with 4 years of follow-up available. Of these, 145 patients traveled 50 miles or less and 83 patients traveled greater than 50 miles. Patient demographics were similar between the two groups. Those who traveled more had statistically higher probability of attrition up to 3-year follow-up mark. There was no difference in percent excess weight loss at each follow-up visit between the two cohorts. Furthermore, there was no difference in readmission rates (2% vs 5%), minor complications (14% vs 10%), major complications (3% vs 2%) and LOS (2.6 days vs 2.6).

CONCLUSION

The distance patients traveled for bariatric surgery did not affect their weight loss success, length of stay, postsurgical complications or readmission rate. Despite the lack of influence on postoperative outcomes, follow-up compliance was statistically affected by distance.

Systematic Review and Meta-analysis of the Change in Ghrelin Levels After Roux-en-Y Gastric Bypass

BACKGROUND

Roux-en-Y gastric bypass (RYGB) is considered effective for weight loss and for treatment of many obesity-related metabolic diseases. Ghrelin is an essential orexigenic peptide that plays an indispensable role in controlling body weight and energy homeostasis of post-operative patients. This systematic review and meta-analysis aimed to investigate changes in the level of fasting total ghrelin following RYGB.

METHODS

A systematic literature search of PubMed, EMBASE, and the Cochrane Library until April 2018 with keywords "ghrelin" and "gastric bypass" was performed in accordance with the MOOSE guidelines and PRISMA statement. Three reviewers independently selected the studies and extracted data. Quality assessment of the included studies was undergone. A random effects model was employed to calculate overall effect sizes. Subgroup analyses and meta-regression were subsequently performed.

RESULTS

Sixteen studies with 325 patients were included. We found ghrelin levels had an increasing tendency (SMD = 0.30; 95% CI = 0.04 to 0.57) despite moderate heterogeneity (I² = 58%). Subsequent subgroup analysis indicated that ghrelin levels decreased (SMD = - 0.49; 95% CI = - 0.98 to 0.00) in the short term (≤ 3 months) and increased (SMD = 0.46; 95% CI = 0.22 to 0.69) in the long term (> 3 months) after RYGB. Meta-regression showed that gastric pouch volume, alimentary limb length and biliopancreatic limb length were not associated with changes in ghrelin levels.

CONCLUSION

Fasting total ghrelin levels decreased in the short term (≤ 3 months) and increased in the long term (> 3 months) after RYGB.

Recent Advances in the Neurobiology of Altered Motivation Following Bariatric Surgery

PURPOSE OF REVIEW

There is compelling evidence in the clinical population that long-term weight loss secondary to bariatric surgery is mitigated by the reemergence of maladaptive feeding behaviors and in some cases new onset substance abuse.

RECENT FINDINGS

A review of the current literature suggests that physical restructuring of the GI tract during WLS alters secretion of feeding peptides and nutrient-sensing mechanisms that directly target the brain's endogenous reward system, the mesolimbic dopamine system. Post-surgical changes in GI physiology augment activation of the mesolimbic system. In some patients, this process may contribute to a reduced appetite for palatable food whereas in others it may support maladaptive motivated behavior for food and chemical drugs. It is concluded that future studies are required to detail the timing and duration of surgical-induced changes in GI-mesolimbic communication to more fully understand this phenomenon.

Influence of post-Roux-en-Y gastric bypass weight recidivism on insulin resistance: a 3-year follow-up

BACKGROUND

Although some early metabolic benefits provided by bariatric surgery are known to occur regardless of weight loss, the impact of mid- to long-term weight recidivism after Roux-en-Y gastric bypass (RYGB) on metabolic outcomes is not profoundly understood.

OBJECTIVE

To investigate the effect of weight recidivism on insulin resistance among nondiabetic individuals with morbid obesity after RYGB during a 3-year follow-up.

SETTING

Public tertiary university hospital.

METHODS

This is a cohort study based on a prospectively collected database of a public tertiary university hospital, which enrolled individuals with morbid obesity who underwent RYGB and were followed-up for 3 years. Weight loss was classified into the following 3 categories: (1) no weight regain; (2) expected regain (regain ≤20% of the maximum weight loss); and (3) obesity recidivism (regain >20% of the maximum weight loss). Homeostasis model assessment (HOMA) values were compared over time.

RESULTS

Of 100 patients, 20% presented obesity recidivism and 52% an expected regain after 3 years of surgery; 28% showed no regain. The recidivism group presented a significant increase in HOMA 3 years after surgery (P = .02). The recidivism group presented a significantly higher HOMA 3 years after surgery than the observed in the other groups (P < .001), as well as a significantly higher percentage of HOMA variation throughout the follow-up (P = .02).

CONCLUSION

Weight recidivism after RYGB was significantly associated with a worsening of insulin resistance among nondiabetic individuals with morbid obesity. Thus, weight loss seems to play a significant role in the maintenance of the early metabolic improvement achieved after RYGB.

GLP-1: Molecular mechanisms and outcomes of a complex signaling system

Meal ingestion provokes the release of hormones and transmitters, which in turn regulate energy homeostasis and feeding behavior. One such hormone, glucagon-like peptide-1 (GLP-1), has received significant attention in the treatment of obesity and diabetes due to its potent incretin effect. In addition to the peripheral actions of GLP-1, this hormone is able to alter behavior through the modulation of multiple neural circuits. Recent work that focused on elucidating the mechanisms and outcomes of GLP-1 neuromodulation led to the discovery of an impressive array of GLP-1 actions. Here, we summarize the many levels at which the GLP-1 signal adapts to different systems, with the goal being to provide a background against which to guide future research.

Metabolic Effects of Bile Acids: Potential Role in Bariatric Surgery

Bariatric surgery is the most effective and durable treatment for morbid obesity, with an unexplained yet beneficial side effect of restoring insulin sensitivity and improving glycemia, often before weight loss is observed. Among the many contributing mechanisms often cited, the altered handling of intestinal bile acids is of considerable therapeutic interest. Here, we review a growing body of literature examining the metabolic effects of bile acids ranging from their physical roles in dietary fat handling within the intestine to their functions as endocrine and paracrine hormones in potentiating responses to bariatric surgery. The roles of 2 important bile acid receptors, Takeda G-protein coupled receptor (also known as G-protein coupled bile acid receptor) and farnesoid X receptor, are highlighted as is downstream signaling through glucagon-like polypeptide 1 and its cognate receptor. Additional improvements in other phenotypes and potential contributions of commensal gut bacteria, such as Akkermansia muciniphila, which are manifest after Roux-en-Y gastric bypass and other emulations, such as gallbladder bile diversion to the ileum, are also discussed.

Surgical treatment of obesity

Obesity prevalence continues to increase worldwide, as do the numerous chronic diseases associated with obesity, including diabetes, non-alcoholic fatty liver disease, dyslipidemia, and hypertension. The prevalence of bariatric surgery also continues to increase and remains the most effective and sustainable treatment for obesity. Over the last several years, numerous prospective and longitudinal studies have demonstrated the benefits of bariatric surgery on weight loss, mortality, and other chronic diseases. Even though the mechanisms underlying many of these beneficial effects remain poorly understood, surgical management of obesity continues to increase given its unmatched efficacy. In this commentary, we discuss recent clinical advancements as well as several areas needed for future research, including indications for bariatric and metabolic surgery, determination of responders and non-responders, metabolic surgery in non-obese individuals, and the evolving role of bariatric surgery in adolescents.

Pediatric Nonalcoholic Fatty Liver Disease: the Rise of a Lethal Disease Among Mexican American Hispanic Children

Hispanic children of Mexican origin have a high incidence of NAFLD. Susceptibility has been linked to a combination of factors including an increasing epidemic of obesity in children and adolescents, an allele substitution in the PNPLA3 gene that reduces hepatic lipid catabolism, and an altered microbiome that may increase hepatic endotoxins. The combination of NAFLD and portal vein toxins secondary to an indigenous gut microbiome appear to lead to the early occurrence of NASH, which progresses to cirrhosis and early hepatocellular carcinoma. Early detection and treatment of hepatic changes are needed. Given the success of gastric bypass in reducing body weight, modifying the gut microbiome, and improving NAFLD/NASH in adults, a trial of gastric bypass in predisposed pediatric candidates should be undertaken.

Weight regain after Roux-en-Y gastric bypass has a large negative impact on the Bariatric Quality of Life Index

BACKGROUND

Despite initial successful weight loss, some patients may experience weight regain following Roux-en-Y gastric bypass (RYGB).

OBJECTIVE

To assess the impact of weight regain on bariatric patients' quality of life (QoL).

METHODS

This was a prospective cross-sectional study. Fifty-six consecutive RYGB patients were recruited and divided into weight-regain and weight-stable cohorts. QoL was assessed using the Bariatric Quality of Life (BQL) questionnaire. The BQL Index scores of the weight-regain and weight-stable groups were compared using Student's t-test. Additionally, the BQL Index score of the weight-regain group was compared with that of historical prebariatric patients. Predictors of BQL were assessed using univariate and multivariate linear regression analyses.

RESULTS

Of 56 RYGB patients, 41 (73%) had weight regain. On average, patients had body mass index (BMI) of 37 ±7.5 kg/m2 and gained 34 ±26% of maximal weight initially lost. Weight-regain patients had lower BQL Index scores than weight-stable patients (44.8±6 vs 53±7, p<0.001). Patients with weight regain had similar BQL Index scores as the prebariatric patients despite lower BMI (BMI of 39.7±6.8 vs 47.2±7.6, p<0.05; BQL Index of 44.8±6 vs 41.6±10.4, p=0.144, respectively). Years from RYGB, BMI and amount of weight regain were associated with BQL Index on a univariate analysis (β=-0.55,-0.52, -0.7; p<0.0001). Only weight regain was a significant predictor of BQL on a multivariate analysis (β =-0.56; p=0.001).

CONCLUSION

Weight regain had a negative impact on bariatric patients' QoL. Patients who regained at least 15% of maximal weight lost appeared to have as low QoL as those who had not undergone bariatric surgery despite a lower BMI.

Metabolic responses to exogenous ghrelin in obesity and early after Roux-en-Y gastric bypass in humans

AIMS

Ghrelin is a gastric-derived hormone that stimulates growth hormone (GH) secretion and has a multi-faceted role in the regulation of energy homeostasis, including glucose metabolism. Circulating ghrelin concentrations are modulated in response to nutritional status, but responses to ghrelin in altered metabolic states are poorly understood. We investigated the metabolic effects of ghrelin in obesity and early after Roux-en-Y gastric bypass (RYGB).

MATERIALS AND METHODS

We assessed central and peripheral metabolic responses to acyl ghrelin infusion (1 pmol kg-1  min-1 ) in healthy, lean subjects (n = 9) and non-diabetic, obese subjects (n = 9) before and 2 weeks after RYGB. Central responses were assessed by GH and pancreatic polypeptide (surrogate for vagal activity) secretion. Peripheral responses were assessed by hepatic and skeletal muscle insulin sensitivity during a hyperinsulinaemic-euglycaemic clamp.

RESULTS

Ghrelin-stimulated GH secretion was attenuated in obese subjects, but was restored by RYGB to a response similar to that of lean subjects. The heightened pancreatic polypeptide response to ghrelin infusion in the obese was attenuated after RYGB. Hepatic glucose production and hepatic insulin sensitivity were not altered by ghrelin infusion in RYGB subjects. Skeletal muscle insulin sensitivity was impaired to a similar degree in lean, obese and post-RYGB individuals in response to ghrelin infusion.

CONCLUSIONS

These data suggest that obesity is characterized by abnormal central, but not peripheral, responsiveness to ghrelin that can be restored early after RYGB before significant weight loss. Further work is necessary to fully elucidate the role of ghrelin in the metabolic changes that occur in obesity and following RYGB.

Plasma amino acids, adiposity, and weight change after gastric bypass surgery: are amino acids associated with weight regain?

PURPOSE

Plasma concentrations of several amino acids (AAs) are positively correlated with obesity. The aim of this study was to examine if selected plasma AAs are associated with weight regain from 2 to 4 years after Roux-en-Y gastric bypass (RYGB).

METHODS

In a prospective study with 165 patients, we examined the relationship between plasma aromatic AAs (AAAs), branched chain AAs (BCAAs), and total cysteine (tCys) 2 years after RYGB, with BMI at 2 years and with weight change from 2 to 4 years after surgery. Analyses were adjusted for relevant covariates.

RESULT

The investigated AAs at 2 years correlated positively with BMI at 2 years (P ≤ 0.003 for all). BCAAs and AAAs at 2 years correlated inversely with % weight loss from 0 to 2 years (P = 0.002 and P = 0.001, respectively), while the association was not significant for tCys (r = -0.14, P = 0.08). Plasma tCys at 2 years correlated positively with BMI at 4 years (P = 0.010) and with weight regain from 2 to 4 years (P = 0.015).

CONCLUSION

Plasma AAAs, BCAAs, and tCys at 2 years were associated with BMI at 2 years. In addition, plasma AAAs and BCAAs at 2 years were associated with weight loss from 0 to 2 years, while tCys at 2 years was associated with weight regain from 2 to 4 years after RYGB. These results suggest that high tCys at 2 years may be used as a prognostic marker for future weight regain. The study was registered in ClinicalTrials.gov (NCT0 1270451).

Bile acids and bariatric surgery

Bariatric surgery, specifically Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG), are the most effective and durable treatments for morbid obesity and potentially a viable treatment for type 2 diabetes (T2D). The resolution rate of T2D following these procedures is between 40 and 80% and far surpasses that achieved by medical management alone. The molecular basis for this improvement is not entirely understood, but has been attributed in part to the altered enterohepatic circulation of bile acids. In this review we highlight how bile acids potentially contribute to improved lipid and glucose homeostasis, insulin sensitivity and energy expenditure after these procedures. The impact of altered bile acid levels in enterohepatic circulation is also associated with changes in gut microflora, which may further contribute to some of these beneficial effects. We highlight the beneficial effects of experimental surgical procedures in rodents that alter bile secretory flow without gastric restriction or altering nutrient flow. This information suggests a role for bile acids beyond dietary fat emulsification in altering whole body glucose and lipid metabolism strongly, and also suggests emerging roles for the activation of the bile acid receptors farnesoid x receptor (FXR) and G-protein coupled bile acid receptor (TGR5) in these improvements. The limitations of rodent studies and the current state of our understanding is reviewed and the potential effects of bile acids mediating the short- and long-term metabolic improvements after bariatric surgery is critically examined.

Revisional Bariatric/Metabolic Surgery: What Dictates Its Indications?

Bariatric/metabolic surgery is currently the only effective long-term treatment for morbid obesity- and obesity-related diseases such as diabetes, heart disease, hypertension, obstructive sleep apnea, and dyslipidemia. In addition, bariatric/metabolic surgery has been shown to significantly reduce the incidence of diabetes and cancer and prolong life when compared to non-surgical therapies. However, as obesity is a chronic disease, recidivism of weight and comorbid conditions can occur. In addition, the surgical construct can lead to long-term consequences such as marginal ulceration, bowel obstruction, reflux, and nutritional deficiencies. Despite these drawbacks, prospective randomized controlled studies and long-term longitudinal population-based comparative studies greatly favor surgical intervention as opposed to traditional lifestyle, diet, and exercise programs. Revisional surgery can be quite complex and technically challenging and may offer the patient a wide variety of solutions for treatment of weight recidivism and complications after primary operations. Given the paucity of high quality published data, we have endeavored to provide indications for revisions after bariatric surgery.

Weight regain after gastric bypass: etiology and treatment options

Roux-en-Y gastric bypass (RYGB) is one of the most common operations performed for the patients with morbid obesity. Weight regain (WR) is a complication that may decrease efficiency of the surgical treatment and demand further interventions. Different factors including lifestyle, mental health, hormonal/metabolic and surgical plays role in WR after RYGB. Various treatment options have been proposed for WR. Conservative treatment is less effective than surgery. Endoscopic refashioning of gastric pouch/stoma fails to achieve sustainable weight loss. Surgical reduction of pouch has acceptable short-term results, but WR after 3 years is substantial. Banded gastric bypass achieves good short-term results, but long-term follow-up data are needed. Distalization of RYGB has a high risk of protein calorie malnutrition (PCM) and conversion to BP diversion (BPD)/duodenal switch (DS) is a technically demanding procedure. Both procedures achieve sustainable long-term weight loss. More studies are needed to explore long-term results of various surgical interventions for WR after RYGB.

Gastric bypass surgery reveals independency of obesity and diabetes melitus type 2

BACKGROUND

Roux-en-Y gastric bypass surgery is widely applied to ameliorate morbid obesity, including diabetes in people with type 2 diabetes. The latter vanish a few days after surgery for many, but not in all patients before any weight reduction has occurred. The explanation for this change in metabolic status is poorly understood, but the observation may suggest that the fate obesity and diabetes is only partly linked after surgery.

METHODS

The trajectories of weight reduction measured as reduced body mass index (BMI) in 741obese subjects with and without diabetes were evaluated. Evaluation was performed on three groups: 1) subjects that were non-diabetic before and after surgery; 2) subjects that were diabetics before surgery but non-diabetics after surgery; and 3) subjects that were diabetics before surgery and remained diabetics after surgery. The diabetic state was established at HbA1c above 48 mmol/mol.

RESULTS

The trajectories differ significantly between groups and any sub-populations of groups, the latter identified by the distance between individual trajectories using a k-means procedure. The results suggest that different domains in the enormous genetic network governing basic metabolism are perturbed in obesity and diabetes, and in fact some of the patients are affected by two distinct diseases: obesity and diabetes mellitus type 2.

CONCLUSION

Although RYGB "normalized" many glycaemic parameters in some of the diabetic subjects apparently converting to a non-diabetics state, other diabetic subjects stay diabetic in the context of the new gut anatomy after surgery. Thus, the obesity part of the glycaemic derangement may have been ameliorated, but some defects of the diabetic state had not.

Effect of Sleeve Gastrectomy Plus Side-to-Side Jejunoileal Anastomosis for Type 2 Diabetes Control in an Obese Rat Model

BACKGROUND

Sleeve gastrectomy plus side-to-side jejunoileal anastomosis (JI-SG), a relatively new approach to bariatric surgeries, has shown promising results for treating obesity and metabolic comorbidities. This study investigated the feasibility and safety of JI-SG in weight loss and diabetes remission compared with sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB).

METHODS

Forty 10-week-old male Zucker diabetic fatty rats were randomly assigned to four groups: control, SG, JI-SG, and RYGB. Their body weights, food intake, and levels of gut hormones (ghrelin, insulin, and glucagon-like peptide-1 (GLP-1)) and lipids were measured.

RESULTS

Rats in the SG, JI-SG, and RYGB groups demonstrated lower food intake and more weight loss 2 weeks postoperatively compared with control rats. Furthermore, rats in the JI-SG group achieved more weight loss (mean 242.7 ± 11.2 g) compared with those in the SG and RYGB groups (SG, 401.4 ± 15.1 g and RYGB, 298 ± 12 g, both P < 0.01). All surgery groups demonstrated a decreased fasting insulin, serum glucose, lipid levels, and increased GLP-1 postoperatively. The JI-SG group had lower fasting ghrelin levels than the RYGB group (168 ± 19.8 ng/L vs. 182 ± 16.7 ng/L, P < 0.01) and higher fasting GLP-1 levels than the SG group (1.99 ± 0.11 pmol/L vs. 1.71 ± 0.12 pmol/L, P < 0.01) at 12 weeks postoperatively. Over the experimental period, the ghrelin levels slowly increased in all surgical groups but remained lower than the preoperative and control levels.

CONCLUSIONS

JI-SG induced higher ghrelin and GLP-1 levels and improved glycemic control in Zucker diabetic fatty rats. Compared with SG and RYGB, JI-SG appeared to be a simple, relatively safe, and more effective procedure for treating type 2 diabetes and obesity in this animal model.

Recent advances in metabolic and bariatric surgery

Obesity and its associated medical conditions continue to increase and add significant burden to patients, as well as health-care systems, worldwide. Bariatric surgery is the most effective treatment for severe obesity and its comorbidities, and resolution of diabetes is weight loss-independent in the case of some operations. Although these weight-independent effects are frequently described clinically, the mechanisms behind them are not well understood and remain an intense area of focus in the growing field of metabolic and bariatric surgery. Perceptions of the mechanisms responsible for the beneficial metabolic effects of metabolic/bariatric operations have shifted from being mostly restrictive and malabsorption over the last 10 to 15 years to being more neuro-hormonal in origin. In this review, we describe recent basic and clinical findings of the major clinical procedures (adjustable gastric banding, vertical sleeve gastrectomy, Roux-en-Y gastric bypass, and biliopancreatic diversion) as well as other experimental procedures (ileal interposition and bile diversion) that recapitulate many of the metabolic effects of these complex operations in a simpler fashion. As the role of bile acids and the gut microbiome on metabolism is becoming increasingly well described, their potential roles in these improvements following metabolic surgery are becoming better appreciated. Bile acid and gut microbiome changes, in light of recent developments, are discussed in the context of these surgical procedures, as well as their implications for future study.

Legacy effects of short-term intentional weight loss on total body and thigh composition in overweight and obese older adults

Objective:

Weight regain following intentional weight loss may negatively impact body composition, accelerating fat regain and increasing risk of physical disability. The purpose of this study was to compare long-term changes in whole body and thigh composition in obese older adults who intentionally lost and then partially regained weight to obese older adults who remained weight stable.

Subjects/Methods:

This pilot study analyzed total body (dual-energy X-ray absorptiometry (DXA)) and thigh (computed tomography (CT)) composition data collected from 24 older (65–79 years) adults 18 months after completion of a 5-month randomized trial that compared resistance training alone (RT) with RT plus caloric restriction (RT+CR).

Results:

Mean loss of body mass in the RT+CR group (n=13) was 7.1±2.4 kg during the 5-month intervention (74% fat mass; 26% lean mass; all P<0.01), whereas RT (n=11) remained weight stable (+0.3±1.8 kg; P=0.64). Differential group effects were observed for all DXA and CT body composition measures at 5 months (all P⩽0.01); however, by 23 months, group differences persisted only for total body (RT+CR: 81.6±10.0 kg vs RT: 88.5±14.9 kg; P=0.03) and lean (RT+CR: 50.8±9.3 kg vs RT: 54.4±12.0 kg; P<0.01) mass. All RT+CR participants regained weight from 5 to 23 months (mean gain=+4.8±2.6 kg; P<0.01). Total fat mass and all thigh fat volumes increased, whereas thigh muscle volume decreased, during the postintervention follow-up in RT+CR (all P⩽0.01). In the RT group, body mass did not change from 5 to 23 months (−0.2±0.9 kg; P=0.87). Decreased total thigh volume, driven by the loss of thigh muscle volume, were the only postintervention body composition changes observed in the RT group (both P<0.04).

Conclusions:

Short-term body composition benefits of an RT+CR intervention may be lost within 18 months after completion of the intervention.

Caloric restriction for treatment of geriatric obesity: Do the benefits outweigh the risks?

Most evidence for the health benefits of prescribing caloric restriction (CR) for weight loss is derived from randomized, controlled trials (RCTs) in young/middle-aged adults; there are very few RCTs in older adults in which the isolated effects of CR can be deciphered. The purpose of this review is to summarize the RCT evidence of the benefits (and potential risks) of CR for the treatment of obesity in older adults. We identified only 19 published papers from 10 RCTs ranging from 3 to 18 months that met the criteria of independent effects of a CR component and were conducted in adults with a mean age ≥65 yrs. Overall, the results show a beneficial treatment effect for improving some metabolic, functional and body composition outcomes with few documented risks. However, all outcomes were assessed immediately after treatment cessation. Thus, until additional scientifically rigorous evidence with long-term follow-up is available, the risk-to-benefit ratio of CR for the treatment of obesity in older adults remains unclear.

What is the Mechanism Behind Weight Loss Maintenance with Gastric Bypass?

Obesity is an epidemic on the rise. With the failure of non-surgical strategies, bariatric surgery has emerged as the most effective therapeutic option for the treatment of severe obesity. Among various surgical options, Roux-en-Y gastric bypass (RYGB) results in sustained weight loss and profound metabolic improvements. The traditional view that gastric bypass and bariatric surgery in general works primarily through restriction/malabsorption of nutrients has become obsolete. It is now increasingly recognised that its mechanisms of action are primarily physiologic, not mechanic. In fact, clinical and translational studies over the last decade have shown that a number of gastrointestinal mechanisms, including changes in gut hormones, neural signalling, intestinal flora, bile acid and lipid metabolism can play a significant role in the effects of this procedure on energy homeostasis. The clinical efficacy and mechanisms of action of RYGB provide a compelling evidence for the role of the gastrointestinal tract in the regulation of appetite and satiety, body weight and glucose metabolism. This review discusses the physiologic changes that occur after RYGB and that contribute to its mechanisms of action.