Sex- and operation-dependent effects on 5-year weight loss results of bariatric surgery.

BACKGROUND: Weight loss response after bariatric surgery is highly variable, and several demographic factors are associated with differential responses to surgery. Preclinical studies demonstrate numerous sex-specific responses to bariatric surgery, but whether these responses are also operation dependent is unknown. OBJECTIVE: To examine sex-specific weight loss outcomes up to 5 years after laparoscopic Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG). SETTING: Single center, university, United States. METHODS: Retrospective, observational cohort study including RYGB (n = 5057) and vertical SG (n = 2041) patients from a single, academic health center. Percentage total weight loss (TWL) over time was examined with generalized linear mixed models to determine the main and interaction effects of surgery type on weight loss by sex. RESULTS: TWL demonstrated a strong sex-by-procedure interaction, with women having a significant advantage with RYGB compared with SG (adjusted difference at 5 yr: 8.0% [95% CI: 7.5-8.5]; P < .001). Men also experienced greater TWL over time with RYGB or SG, but the difference was less and clinically insignificant (adjusted difference at 5 yr: 2.9% [2.0-3.8]; P < .001; P interaction between sex and procedure type = .0001). Overall, women had greater TWL than men, and RYGB patients had greater TWL than SG patients (adjusted difference at 5 yr: 3.1% [2.4-3.2] and 6.9% [6.5-7.3], respectively; both P < .0001). Patients with diabetes lost less weight compared with those without (adjusted difference at 5 yr: 3.0% [2.7-3.2]; P < .0001). CONCLUSIONS: Weight loss after bariatric surgery is sex- and procedure-dependent. There is an association suggesting a clinically insignificant difference in weight loss between RYGB and SG among male patients at both the 2- and 5-year postsurgery time points.

Cardiometabolic Improvements After Metabolic Surgery and Related Presurgery Factors.

Context: Metabolic surgery remains the most effective and durable treatment for severe obesity and related metabolic diseases. Objective: We examined cardiometabolic improvements after metabolic surgery and associated presurgery demographic and clinical factors in a large multiracial cohort. Methods: Included were 7804 patients (20-79 years) undergoing first-time metabolic surgery at Vanderbilt University Medical Center from 1999 to 2022. Pre- and 1-year postsurgery cardiometabolic profiles were extracted from medical records, including body mass index (BMI), blood pressure, blood lipids, glucose, and hemoglobin A1c. The 10-year atherosclerotic cardiovascular disease (ASCVD) risk was estimated per American College of Cardiology/American Heart Association equations. Pre- to postsurgery cardiometabolic profiles were compared by paired t-test, and associated factors were identified by multivariable linear and logistic regression. Results: Among 7804 patients, most were women and White, while 1618 were men and 1271 were Black; median age and BMI were 45 years [interquartile range (IQR): 37-53] and 46.4 kg/m2 (IQR: 42.1-52.4). At 1-year postsurgery, patients showed significant decreases in systolic blood pressure (10.5 [95% confidence interval: 10.1, 10.9] mmHg), total cholesterol (13.5 [10.3, 16.7] mg/dL), glucose (13.6 [12.9, 14.4] mg/dL), hemoglobin A1c (1.13% [1.06, 1.20]), and 10-year ASCVD risk (absolute reduction: 1.58% [1.22, 1.94]; relative reduction: 34.4% [29.4, 39.3]); all P < .0001. Older, male, or Black patients showed less reduction in 10-year ASCVD risk and lower odds of diabetes/hypertension/dyslipidemia remission than younger, female, or White patients. Patients with a history of diabetes, hypertension, dyslipidemia, or cardiovascular disease showed less cardiometabolic improvements than those without. Results were similar with or without further adjusting for weight loss and largely sustained at 2-year postsurgery. Conclusion: Metabolic surgery results in significant cardiometabolic improvements, particularly among younger, female, or White patients and those without comorbidities.

Enhanced Patient Portal Engagement Associated with Improved Weight Loss Outcomes in Post-Bariatric Surgery Patients.

Background: Bariatric surgery is an effective intervention for obesity, but it requires comprehensive postoperative self-management to achieve optimal outcomes. While patient portals are generally seen as beneficial in engaging patients in health management, the link between their use and post-bariatric surgery weight loss remains unclear. Objective: This study investigated the association between patient portal engagement and postoperative body mass index (BMI) reduction among bariatric surgery patients. Methods: This retrospective longitudinal study included patients who underwent Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) at Vanderbilt University Medical Center (VUMC) between January 2018 and March 2021. Using generalized estimating equations, we estimated the association between active days of postoperative patient portal use and the reduction of BMI percentage (%BMI) at 3, 6, and 12 months post-surgery. Covariates included duration since surgery, the patient's age at the time of surgery, gender, race and ethnicity, type of bariatric surgery, severity of comorbid conditions, and socioeconomic disadvantage. Results: The study included 1,415 patients, mostly female (80.9%), with diverse racial and ethnic backgrounds. 805 (56.9%) patients underwent RYGB and 610 (43.1%) underwent SG. By one-year post-surgery, the mean (SD) %BMI reduction was 31.1% (8.3%), and the mean (SD) number of patient portal active days was 61.0 (41.2). A significantly positive association was observed between patient portal engagement and %BMI reduction, with variations revealed over time. Each 10-day increment of active portal use was associated with a 0.57% ([95% CI: 0.42- 0.72], P < .001) and 0.35% ([95% CI: 0.22- 0.49], P < .001) %BMI reduction at 3 and 6 months postoperatively. The association was not statistically significant at 12 months postoperatively (ß=-0.07, [95% CI: -0.24- 0.09], P = .54). Various portal functions, including messaging, visits, my record, medical tools, billing, resources, and others, were positively associated with %BMI reduction at 3- and 6-months follow-ups. Conclusions: Greater patient portal engagement, which may represent stronger adherence to postoperative instructions, better self-management of health, and enhanced communication with care teams, was associated with improved postoperative weight loss. Future investigations are needed to identify important portal features that contribute to the long-term success of weight loss management.

Weight-independent effects of Roux-en-Y gastric bypass surgery on remission of nonalcoholic fatty liver disease in mice.

OBJECTIVE: Obesity is a driver of non-alcoholic fatty liver disease (NAFLD), and interventions that decrease body weight, such as bariatric surgery and/or calorie restriction (CR), may serve as effective therapies. This study compared the effects of Roux-en-Y gastric bypass surgery (RYGB) and CR on hepatic function in mice with obesity and NAFLD. METHODS: C57BL/6J mice were fed a high-fat diet to promote obesity. At 16 weeks of age, mice were randomized to sham surgery (sham), RYGB, or CR weight matched to RYGB (WM). Body weight/composition, food intake, and energy expenditure (EE) were measured throughout treatment. Liver histopathology was evaluated from H&E-stained sections. Hepatic enzymes and glycogen content were determined by ELISA. Transcriptional signatures were revealed via RNA sequencing. RESULTS: RYGB reduced hepatic lipid content and adiposity while increasing EE and lean body mass relative to WM. Hepatic glycogen and bile acid content were increased after RYGB relative to sham and WM. RYGB activated enterohepatic signaling and genes regulating hepatic lipid homeostasis. CONCLUSIONS: RYGB improved whole-body composition and hepatic lipid homeostasis to a greater extent than CR in mice. RYGB was associated with discrete remodeling of the hepatic transcriptome, suggesting that surgery may be mechanistically additive to CR.

Bariatric surgery alters mitochondrial function in gut mucosa.

BACKGROUND: The obesity pandemic has worsened global disease burden, including type 2 diabetes, cardiovascular disease, and cancer. Metabolic/bariatric surgery (MBS) is the most effective and durable obesity treatment, but the mechanisms underlying its long-term weight loss efficacy remain unclear. MBS drives substrate oxidation that has been linked to improvements in metabolic function and improved glycemic control that are potentially mediated by mitochondria-a primary site of energy production. As such, augmentation of intestinal mitochondrial function may drive processes underlying the systemic metabolic benefits of MBS. Herein, we applied a highly sensitive technique to evaluate intestinal mitochondrial function ex vivo in a mouse model of MBS. METHODS: Mice were randomized to surgery, sham, or non-operative control. A simplified model of MBS, ileal interposition, was performed by interposition of a 2-cm segment of terminal ileum into the proximal bowel 5 mm from the ligament of Treitz. After a four-week recovery period, intestinal mucosa of duodenum, jejunum, ileum, and interposed ileum were assayed for determination of mitochondrial respiratory function. Citrate synthase activity was measured as a marker of mitochondrial content. RESULTS: Ileal interposition was well tolerated and associated with modest body weight loss and transient hypophagia relative to controls. Mitochondrial capacity declined in the native duodenum and jejunum of animals following ileal interposition relative to controls, although respiration remained unchanged in these segments. Similarly, ileal interposition lowered citrate synthase activity in the duodenum and jejunum following relative to controls but ileal function remained constant across all groups. CONCLUSION: Ileal interposition decreases mitochondrial volume in the proximal intestinal mucosa of mice. This change in concentration with preserved respiration suggests a global mucosal response to segment specific nutrition signals in the distal bowel. Future studies are required to understand the causes underlying these mitochondrial changes.

Combination anti-obesity medications to effectively treat bariatric surgery weight regain at an academic obesity center.

Background: Combination anti-obesity medications (AOMs) to treat postoperative bariatric surgery weight regain have limited data on their use in the clinical setting. Understanding the optimal treatment protocol in this cohort will maximize weight loss outcomes. Methods: A retrospective review of bariatric surgery patients (N = 44) presenting with weight regain at a single academic multidisciplinary obesity center who were prescribed AOM(s) plus intensive lifestyle modification for 12 months. Results: Age: 28-76 years old, 93% female, mean weight 110.2 ± 20.3 kg, BMI 39.7 ± 7.4 kg/m2, presenting 5.2 ± 1.6 years post-bariatric surgery [27 (61.4%), 14 (31.8%), and 3 (6.8%) laparoscopic Roux-en-Y gastric bypass (RYGB), laparoscopic vertical sleeve gastrectomy (VSG), and open RYGB, respectively], with 15.1 ± 11.1 kg mean weight gain from nadir. Mean weight loss after medical intervention at 3-, 6-, and 12-month time points was 4.4 ± 4.6 kg, 7.3 ± 7.0 kg, and 10.7 ± 9.2 kg, respectively. At 12 months, individuals prescribed 3 or more AOMs lost more weight than those prescribed one (-14.5 ± 9.0 kg vs. -4.9 ± 5.7 kg, p < 0.05) irrespective of age, gender, number of comorbidities, initial weight or BMI, type of surgery, or GLP1 use. RYGB patients lost less weight overall (7.4% vs. 14.8% VSG respectively; p < 0.05). Conclusions: Combination AOMs may be needed to achieve optimal weight loss results to treat post-operative weight regain.

The Vagus Nerve Mediates Gut-Brain Response to Duodenal Nutrient Administration.

BACKGROUND: Obesity contributes significant disease burden worldwide, including diabetes, cardiovascular disease, and cancer. While bariatric surgery is the most effective and durable obesity treatment, the mechanisms underlying its effects remain unknown. Although neuro-hormonal mechanisms have been suspected to mediate at least some of the gut-brain axis changes following bariatric surgery, studies examining the intestine and its regionally specific post-gastric alterations to these signals remain unclear. MATERIALS AND METHODS: Vagus nerve recording was performed following the implantation of duodenal feeding tubes in mice. Testing conditions and measurements were made under anesthesia during baseline, nutrient or vehicle solution delivery, and post-delivery. Solutions tested included water, glucose, glucose with an inhibitor of glucose absorption (phlorizin), and a hydrolyzed protein solution. RESULTS: Vagus nerve signaling was detectable from the duodenum and exhibited stable baseline activity without responding to osmotic pressure gradients. Duodenal-delivered glucose and protein robustly increased vagus nerve signaling, but increased signaling was abolished during the co-administration of glucose and phlorizin. DISCUSSION: Gut-brain communication via the vagus nerve emanating from the duodenum is nutrient sensitive and easily measurable in mice. Examination of these signaling pathways may help elucidate how the nutrient signals from the intestine are altered when applied to obesity and bariatric surgery mouse models. Future studies will address quantifying the changes in neuroendocrine nutrient signals in health and obesity, with specific emphasis on identifying the changes associated with bariatric surgery and other gastrointestinal surgery.

Physiology Reconfigured: How Does Bariatric Surgery Lead to Diabetes Remission?

Bariatric surgery improves glucose homeostasis and glycemic control in patients with type 2 diabetes. Over the past 20 years, a breadth of studies has been conducted in humans and rodents aimed to identify the regulatory nodes responsible for surgical remission of type 2 diabetes. The review herein discusses central mechanisms of type 2 diabetes remission associated with weight loss and surgical modification of the gastrointestinal tract.

Regulation of body weight: Lessons learned from bariatric surgery.

BACKGROUND: Bariatric or weight loss surgery is currently the most effective treatment for obesity and metabolic disease. Unlike dieting and pharmacology, its beneficial effects are sustained over decades in most patients, and mortality is among the lowest for major surgery. Because there are not nearly enough surgeons to implement bariatric surgery on a global scale, intensive research efforts have begun to identify its mechanisms of action on a molecular level in order to replace surgery with targeted behavioral or pharmacological treatments. To date, however, there is no consensus as to the critical mechanisms involved. SCOPE OF REVIEW: The purpose of this non-systematic review is to evaluate the existing evidence for specific molecular and inter-organ signaling pathways that play major roles in bariatric surgery-induced weight loss and metabolic benefits, with a focus on Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG), in both humans and rodents. MAJOR CONCLUSIONS: Gut-brain communication and its brain targets of food intake control and energy balance regulation are complex and redundant. Although the relatively young science of bariatric surgery has generated a number of hypotheses, no clear and unique mechanism has yet emerged. It seems increasingly likely that the broad physiological and behavioral effects produced by bariatric surgery do not involve a single mechanism, but rather multiple signaling pathways. Besides a need to improve and better validate surgeries in animals, advanced techniques, including inducible, tissue-specific knockout models, and the use of humanized physiological traits will be necessary. State-of-the-art genetically-guided neural identification techniques should be used to more selectively manipulate function-specific pathways.

Effect of high-risk factors on postoperative major adverse cardiovascular and cerebrovascular events trends following bariatric surgery in the United States from 2012 to 2019.

BACKGROUND: Recent examination of trends in postoperative major adverse cardiovascular and cerebrovascular events (MACE) following bariatric surgery, including accredited and nonaccredited centers, and the factors affecting those trends, is lacking. OBJECTIVES: The objective of this study was to evaluate current trends for postoperative MACE after bariatric surgery in both accredited and nonaccredited centers and the factors affecting these trends. SETTING: This retrospective study was conducted using National Inpatient Sample database from 2012 to 2019. METHODS: All patients who underwent inpatient laparoscopic sleeve gastrectomy (LSG), open sleeve gastrectomy (SG), laparoscopic Roux-en-Y gastric bypass (LRYGB), and open Roux-en-Y gastric bypass (RYGB) were examined. Composite MACE (acute myocardial infarction, cardiac arrest, acute stroke, and in-hospital death during bariatric surgery hospitalization) was calculated and analyzed over time along with patient demographic and co-morbid diseases using survey-weighted logistic regression. RESULTS: MACE incidence was lowest for LSG (0.07%), followed by LRYGB (0.16%), SG (3.47%), and RYBG (3.51%). Open procedure, increasing age, male sex, body mass index ≥50, coronary artery disease, congestive heart failure, and chronic kidney disease were independent predictors for increased MACE risk. MACE incidence increased over time for SG (odds ratio [OR] 1.25 [1.16, 1.34]; P < .0001) and RYGB (OR 1.14 [1.06, 1.22]; P = .0004) but decreased for LRYGB (OR 0.93 [0.87, 1] P = .06). After adjustment for high-risk covariates, increased MACE trend seen over time was attenuated in SG (OR 1.13 [1.04-1.22]; P = .005) and RYGB (OR 1.04 [0.96-1.12]; P = .36), while there was minimal effect of these high-risk covariates on MACE trend over time in LSG and LRYGB. CONCLUSIONS: MACE following LSG and LRYGB is rare, occurring in 0.1% of patients. Persistently increasing high-risk conditions and demographics has had minimal effect on MACE over time for LSG and LRYGB but has had significant effect on MACE trend over time in SG and RYGB.

The role of bariatric and metabolic surgery in the development, diagnosis, and treatment of endometrial cancer.

The obesity pandemic continues to contribute to a worsening burden of disease worldwide. The link between obesity and diseases such as diabetes, cardiovascular disease, and cancer has been well established, yet most patients living with obesity remain untreated or undertreated. Metabolic and bariatric surgery is the most effective and durable treatment for obesity, is safe, and may have a protective benefit with respect to cancer incidence. In this review, an overview of the link between obesity, metabolic surgery, and cancer is discussed with emphasis on indications for endometrial cancer, the malignancy most strongly associated with obesity. Considerable evidence from retrospective and prospective cohort studies supports a decreased risk of endometrial cancer in patients with obesity who undergo bariatric surgery compared with nonsurgical controls. Survivors of endometrial cancer are at increased risk of poor health outcomes associated with obesity, and women with endometrial cancer are more likely to die of cardiovascular disease and other obesity-related illnesses than of the malignancy itself. Recent advances in anticancer drug therapies have targeted pathways that may also be therapeutically altered with metabolic surgery. Metabolic surgery has significant potential to enter the treatment paradigm for endometrial cancer, and gynecologic oncologist visits present an opportunity to identify patients who may benefit the most.

Protein Appetite at the Interface between Nutrient Sensing and Physiological Homeostasis.

Feeding behavior is guided by multiple competing physiological needs, as animals must sense their internal nutritional state and then identify and consume foods that meet nutritional needs. Dietary protein intake is necessary to provide essential amino acids and represents a specific, distinct nutritional need. Consistent with this importance, there is a relatively strong body of literature indicating that protein intake is defended, such that animals sense the restriction of protein and adaptively alter feeding behavior to increase protein intake. Here, we argue that this matching of food consumption with physiological need requires at least two concurrent mechanisms: the first being the detection of internal nutritional need (a protein need state) and the second being the discrimination between foods with differing nutritional compositions. In this review, we outline various mechanisms that could mediate the sensing of need state and the discrimination between protein-rich and protein-poor foods. Finally, we briefly describe how the interaction of these mechanisms might allow an animal to self-select between a complex array of foods to meet nutritional needs and adaptively respond to changes in either the external environment or internal physiological state.

Association of Bariatric Surgery With Major Adverse Liver and Cardiovascular Outcomes in Patients With Biopsy-Proven Nonalcoholic Steatohepatitis.

IMPORTANCE: No therapy has been shown to reduce the risk of serious adverse outcomes in patients with nonalcoholic steatohepatitis (NASH). OBJECTIVE: To investigate the long-term relationship between bariatric surgery and incident major adverse liver outcomes and major adverse cardiovascular events (MACE) in patients with obesity and biopsy-proven fibrotic NASH without cirrhosis. DESIGN, SETTING, AND PARTICIPANTS: In the SPLENDOR (Surgical Procedures and Long-term Effectiveness in NASH Disease and Obesity Risk) study, of 25 828 liver biopsies performed at a US health system between 2004 and 2016, 1158 adult patients with obesity were identified who fulfilled enrollment criteria, including confirmed histological diagnosis of NASH and presence of liver fibrosis (histological stages 1-3). Baseline clinical characteristics, histological disease activity, and fibrosis stage of patients who underwent simultaneous liver biopsy at the time of bariatric surgery were balanced with a nonsurgical control group using overlap weighting methods. Follow-up ended in March 2021. EXPOSURES: Bariatric surgery (Roux-en-Y gastric bypass, sleeve gastrectomy) vs nonsurgical care. MAIN OUTCOMES AND MEASURES: The primary outcomes were the incidence of major adverse liver outcomes (progression to clinical or histological cirrhosis, development of hepatocellular carcinoma, liver transplantation, or liver-related mortality) and MACE (a composite of coronary artery events, cerebrovascular events, heart failure, or cardiovascular death), estimated using the Firth penalized method in a multivariable-adjusted Cox regression analysis framework. RESULTS: A total of 1158 patients (740 [63.9%] women; median age, 49.8 years [IQR, 40.9-57.9 years], median body mass index, 44.1 [IQR, 39.4-51.4]), including 650 patients who underwent bariatric surgery and 508 patients in the nonsurgical control group, with a median follow-up of 7 years (IQR, 4-10 years) were analyzed. Distribution of baseline covariates, including histological severity of liver injury, was well-balanced after overlap weighting. At the end of the study period in the unweighted data set, 5 patients in the bariatric surgery group and 40 patients in the nonsurgical control group experienced major adverse liver outcomes, and 39 patients in the bariatric surgery group and 60 patients in the nonsurgical group experienced MACE. Among the patients analyzed with overlap weighting methods, the cumulative incidence of major adverse liver outcomes at 10 years was 2.3% (95% CI, 0%-4.6%) in the bariatric surgery group and 9.6% (95% CI, 6.1%-12.9%) in the nonsurgical group (adjusted absolute risk difference, 12.4% [95% CI, 5.7%-19.7%]; adjusted hazard ratio, 0.12 [95% CI, 0.02-0.63]; P = .01). The cumulative incidence of MACE at 10 years was 8.5% (95% CI, 5.5%-11.4%) in the bariatric surgery group and 15.7% (95% CI, 11.3%-19.8%) in the nonsurgical group (adjusted absolute risk difference, 13.9% [95% CI, 5.9%-21.9%]; adjusted hazard ratio, 0.30 [95% CI, 0.12-0.72]; P = .007). Within the first year after bariatric surgery, 4 patients (0.6%) died from surgical complications, including gastrointestinal leak (n = 2) and respiratory failure (n = 2). CONCLUSIONS AND RELEVANCE: Among patients with NASH and obesity, bariatric surgery, compared with nonsurgical management, was associated with a significantly lower risk of incident major adverse liver outcomes and MACE.