Medical and surgical treatments for obesity have opposite effects on peptide YY and appetite: a prospective study controlled for weight loss

Stronger control of eating 3 months after sleeve gastrectomy predicts successful weight loss outcomes at one year

Background

Weight loss response to sleeve gastrectomy (SG) is variable and predicting the effectiveness of surgery is challenging and elusive. The aim of our study was to assess and quantify the association between eating control and weight loss outcomes and identify the control of eating (CoE) attributes during the early postoperative period that might predict good vs. poor response to SG at one year.

Methods

A prospective longitudinal cohort study using the Control of Eating Questionnaire (CoEQ) was designed as a series before and at 3-, 6-, and 12-months post-SG. Primary outcomes were changes in CoE attributes and percent of total weight loss (%TWL) 12-months post-surgery. Subjects were categorized based on %TWL as good (GR, ≥25 %) or poor responders (PR, <25 %). A receiver operating characteristic and logistic regression analyses were performed.

Results

We included 41 participants (80.5% females, 51.2% Hispanic, mean age 41.7±10.6, median baseline body mass index (BMI) 43.6 kg/m2 [range 35.2-66.3]) who completed the CoEQ at all four timepoints. The "Difficulty to control eating" score at 3 months revealed the highest area under the curve (AUC) (AUC 0.711; 95%CI 0.524-0.898; p=0.032). In a trade-off between a high Youden index and high sensitivity, the "Difficulty to control eating" score of 7 at 3 months was identified as the optimal cut-off for distinguishing between GRs and PRs. Score ≤7 at 3 months was strongly independently associated with a successful weight loss target of 25%TWL at one-year post-SG (Relative Risk 4.43; 95%CI 1.06-18.54; p=0.042).

Conclusion

"Difficulty to control eating" score at 3 months post-SG is an independent early predictor of optimal response (achieving a successful TWL target of ≥25 % at one-year post-SG). Our results support the utility of this easy-to-administer validated tool for predicting the effectiveness of SG and may assist in identifying individuals with suboptimal response early and helping them with interventions to attain optimal weight loss targets.

A Study of Omentum Reduction on the Improvement of Nausea and vomiting and Gastroesophageal Reflux Symptoms After Laparoscopic Gastric Sleeve Resection

OBJECTIVE

To investigate the effect of omentum reduction in laparoscopic sleeve gastrectomy (LSG) on the improvement of postoperative nausea and vomiting and gastroesophageal reflux symptoms.

METHODS

A retrospective study was performed on the case data of 198 obese patients who underwent LSG in the Department of Obesity and Metabolic Diseases of Xiaolan People's Hospital of Zhongshan from March 2021 to March 2022 and were divided into omentum reduction group and control group, with 99 cases in each group, and the preoperative body mass index (BMI) of the patients was recorded. Age, gender, comorbidities, and comparative analysis of operation time, blood loss, length of hospital stay, postoperative nausea and vomiting score, gastroesophageal reflux GerdQ score, postoperative pain score, weight, and postoperative complications were analyzed.

RESULTS

There were no significant differences in preoperative BMI, age, gender and comorbidities between the two groups (P > 0.05), but there were significant differences in intraoperative blood loss and operation time (P < 0.05). There were differences in postoperative nausea and vomiting scores and VAS pain scores between the two groups (P < 0.05). The GerdQ scores of the omental reduction group were 8.11 ± 2.84 points at 1 year, and those in the control group were 7.56 ± 2.67 points, which were 3.97 ± 4.09 points higher than those in the preoperative omentum reduction group and 3.42 ± 3.41 in the control group, with no significant difference (P > 0.05). There was no significant difference in the postoperative excess weight loss rate %EWL and postoperative complications (p > 0.05).

CONCLUSION

Omentum reduction can improve short-term nausea and vomiting after LSG, but it cannot significantly improve long-term reflux symptoms.

Weight-Reducing Dietary Intervention Increases the Ability of Hyperinsulinemia to Suppress Serum Ghrelin Concentration in Individuals with Obesity

BACKGROUND

Ghrelin is an orexigenic peptide secreted mainly by the stomach. Serum ghrelin concentrations are suppressed after a meal, probably due to insulin release. Individuals with obesity are characterized by a lower fasting serum ghrelin and a lower ghrelin decrease after a meal. The effect of weight loss on the ability of insulin to suppress serum ghrelin concentration remains unknown.

OBJECTIVE

The aim of the present study was to analyze the effect of weight-reducing dietary intervention on the ability of hyperinsulinemia to suppress serum ghrelin concentration in young individuals with uncomplicated obesity.

METHODS

We examined 38 individuals with marked overweight or obesity, who underwent a 12-wk dietary intervention program. Serum ghrelin concentration was measured before and after a 2-h hyperinsulinemic-euglycemic clamp, both pre- and post-intervention. Twenty normal-weight individuals served as a control group and were examined at baseline only.

RESULTS

Individuals with overweight/obesity were characterized by a lower fasting serum ghrelin concentration than normal-weight individuals (P = 0.006). Insulin decreased serum ghrelin concentration in both groups (P < 0.001); however, this decrease was markedly lower in individuals with overweight/obesity than in normal-weight individuals (99.70 ± 136.37 vs. 215.45 ± 250.28 pg/mL; P = 0.026). Fasting serum ghrelin concentration increased after the intervention. After weight-reducing dietary intervention, the decrease in serum ghrelin concentration after the clamp was significantly greater than the pre-intervention value (99.70 ± 136.37 vs. 221.82 ± 228.75 pg/mL; P = 0.002).

CONCLUSIONS

Weight-reducing dietary intervention restores the ability of hyperinsulinemia to suppress serum ghrelin concentration. It may suggest an enhanced feeling of satiety after moderate weight loss in individuals with overweight/obesity.

Methodological issues in assessing change in dietary intake and appetite following gastric bypass surgery: A systematic review

Gastric bypass surgery is an effective long-term treatment for individuals with severe obesity. Changes in appetite, dietary intake, and food preferences have all been postulated to contribute to postoperative body weight regulation, however, findings are inconsistent. The aim of this systematic review was to evaluate the current literature on changes in dietary intake and appetite following gastric bypass surgery, in the context of the methodology used and the analysis, interpretation, and presentation of results. Four databases were systematically searched with terms related to "gastric bypass surgery," "appetite," and "dietary intake," and 49 papers (n = 2384 patients after gastric bypass) were eligible for inclusion. The evidence indicated that only a reduction in overall energy intake and an increase in postprandial satiety are maintained beyond 6-month post-surgery, whereas relative macronutrient intake and premeal hunger remain unchanged. However, available data were limited by inconsistencies in the methods, analysis, presentation, and interpretation of results. In particular, there was a reliance on data collected by subjective methods with minimal acknowledgment of the limitations, such as misreporting of food intake. There is a need for further work employing objective measurement of appetite and dietary intake following gastric bypass surgery to determine how these mechanisms may contribute to weight regulation in the longer term.

Do Gut Hormones Contribute to Weight Loss and Glycaemic Outcomes after Bariatric Surgery?

Bariatric surgery is an effective intervention for management of obesity through treating dysregulated appetite and achieving long-term weight loss maintenance. Moreover, significant changes in glucose homeostasis are observed after bariatric surgery including, in some cases, type 2 diabetes remission from the early postoperative period and postprandial hypoglycaemia. Levels of a number of gut hormones are dramatically increased from the early period after Roux-en-Y gastric bypass and sleeve gastrectomy—the two most commonly performed bariatric procedures—and they have been suggested as important mediators of the observed changes in eating behaviour and glucose homeostasis postoperatively. In this review, we summarise the current evidence from human studies on the alterations of gut hormones after bariatric surgery and their impact on clinical outcomes postoperatively. Studies which assess the role of gut hormones after bariatric surgery on food intake, hunger, satiety and glucose homeostasis through octreotide use (a non-specific inhibitor of gut hormone secretion) as well as with exendin 9–39 (a specific glucagon-like peptide-1 receptor antagonist) are reviewed. The potential use of gut hormones as biomarkers of successful outcomes of bariatric surgery is also evaluated.

From Entero-Endocrine Cell Biology to Surgical Interventional Therapies for Type 2 Diabetes

The physiological roles of the enteroendocrine system in relation to energy and glucose homeostasis regulation have been extensively studied in the past few decades. Considerable advances were made that enabled to disclose the potential use of gastro-intestinal (GI) hormones to target obesity and type 2 diabetes (T2D). The recognition of the clinical relevance of these discoveries has led the pharmaceutical industry to design several hormone analogues to either to mitigate physiological defects or target pharmacologically T2D.Amongst several advances, a major breakthrough in the field was the unexpected observation that enteroendocrine system modulation to T2D target could be achieved by surgically induced anatomical rearrangement of the GI tract. These findings resulted from the widespread use of bariatric surgery procedures for obesity treatment, which despite initially devised to induce weight loss by limiting the systemic availably of nutrients, are now well recognized to influence GI hormone dynamics in a manner that is highly dependent on the type of anatomical rearrangement produced.This chapter will focus on enteroendocrine system related mechanisms leading to improved glycemic control in T2D after bariatric surgery interventions.

Oral Hydration, Food Intake, and Nutritional Status Before and After Bariatric Surgery

BACKGROUND AND AIMS

Bariatric surgery is considered to be the most effective treatment of morbid obesity. Sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGBP) are the most popular procedures. We evaluated nutritional status, micro- and macronutrient intake, and oral hydration in patients before and regularly during 1 year after RYGBP and SG.

METHODS

All patients that had been through bariatric surgery with at least 1-year post-surgery were retrospectively included in the study. All participants were evaluated once during the 2 months before the surgery and at 1, 3, 6, and 12 months after surgery. Clinical and biological evaluations as well as dietary investigations were performed.

RESULTS

Fifty-seven patients were included in this study (28 RYGBP and 29 SG). Patients in the RYGBP group had significantly higher body weight (132.3 ± 22 versus 122.2 ± 22.2 kg, p = 0.039) than patients in the SG group. Before surgery, total energy intake, oral hydration, and vitamin and mineral intakes were not different between the two groups. RYGBP and SG induced significant similar excess weight loss 1 year after surgery, 48.6 29.8% and 57.6 27.6% of body weight respectively. Energy intake significantly decreased 1 month after surgery and slightly increased from 1 to 12 months without reaching baseline intake levels. Macronutrient repartition did not change during follow-up. Oral hydration significantly decreased after RYGBP (- 58%) and showed a trend to be decreased after SG (- 49%). Sixty-five percent of patients still had vitamin D deficiency 1 year after surgery. Whatever the type of surgery, more than 20% had some vitamin deficiency 1 month after surgery.

CONCLUSIONS

Calories intake decreases after bariatric surgery, whatever the type of procedure. In addition, the prevalence of vitamin deficiency is high after bariatric surgery. Lastly, oral hydration is importantly decreased after bariatric surgery, especially after RYGBP.

Pre-operative Restraint and Post-operative Hunger, Disinhibition and Emotional Eating Predict Weight Loss at 2 Years Post-laparoscopic Adjustable Gastric Banding

INTRODUCTION

A principal mechanism of action in bariatric surgery is reduction in calorie consumption due to decreased hunger and increased satiety. Patients' ability to perceive post-operative changes to their hunger is therefore central to optimal results. This study examined factors that may impact how patients perceive post-operative hunger and how perception of hunger impacts eating and subsequent weight loss after laparoscopic adjustable gastric banding (LAGB).

METHODS

Patients undertaking LAGB (n = 147) provided pre-surgery and 2-year weight loss data and pre-surgery and 12-month psychological data (perception of hunger, disinhibition related to eating, emotional eating).

RESULTS

Path analysis demonstrated that patients with lower levels of pre-surgery cognitive restraint over eating experienced significantly greater reduction in perception of hunger at 12 months post-surgery. Perceived reduction in hunger was significantly associated with lower levels of both emotional eating and disinhibited eating. Finally, reduced emotional eating at 12 months significantly predicted 9% of the variance in percentage of total weight loss (%TWL) at 2 years after surgery.

CONCLUSION

These initial findings suggest that preparation for bariatric surgery may be enhanced by psychoeducation regarding cognitive restraint over eating and its effect on hunger perception. In addition, psychological treatment that focuses on identifying and responding to changes in hunger may contribute to improved outcomes for those who have difficulty adjusting to post-operative eating behaviours.

The effects of bariatric surgery on psychological aspects of eating behaviour and food intake in humans

Bariatric surgery has emerged as an increasingly popular weight loss intervention, with larger and more endurable weight loss compared to pharmacological and behavioural interventions. The degree of weight loss patients experience varies, between individuals, surgeries and over time. An explanation as to why differing weight loss trajectories exist post-surgery could be due to the complex interplay of individual differences in relation to eating behaviours and appetite. Thus the aim of this narrative review is to explore literature between 2008 and 2018, to assess the impact of impact of bariatric surgery on food selection and nutrient status, on eating behaviour traits and on disturbed and disordered eating behaviour, to determine their impact of weight loss success and weight loss trajectories. Immediately post-surgery, up until 1-2 years post-surgery, there is a reliance upon the surgery's alteration of the gastrointestinal tract to control food intake and subsequently lose weight. Energy intake is reduced, dietary adherence is higher, supplement intake is higher, appetite ratings are lower, there is a reduction in psychopathology, and an increase in wellbeing. After this point, patients become more susceptible to weight regain, as this is the point where passive observation of the weight reducing action of surgery, moves into more cognitive effort, on the part of the individual, to control energy intake. There are various factors which influence an individual's ability to successfully regulate their energy intake post-surgery, such as their level of Disinhibition, Restraint, Hunger, Emotional Eating, Uncontrolled Eating, psychopathology and wellbeing. The need for continued psychological and nutritional support post-surgery is necessary to reduce weight regain susceptibility.

The Role of Bariatric Surgery on Diabetes and Diabetic Care Compliance

PURPOSE OF REVIEW

Bariatric surgery is a durable and long-term solution to treat both obesity and its associated comorbidities, specifically type 2 diabetes mellitus (T2DM). Many studies have demonstrated the benefits of bariatric surgery on T2DM, but weight recidivism along with recurrence of comorbidities can be seen following these procedures. Patient compliance post-bariatric surgery is linked to weight loss outcomes and comorbidity improvement/resolution. The role of compliance with respect to T2DM medication in bariatric patients specifically has not recently been examined. This article seeks to review the role of bariatric surgery on short- and long-term resolution of T2DM, recurrence, and compliance with T2DM medication following bariatric surgery.

RECENT FINDINGS

Seven randomized control trials have examined metabolic surgery versus medical therapy in glycemic control in patients meeting criteria for severe obesity. Six out of seven studies demonstrate a significant advantage in the surgical arms with regards to glycemic control, as well as secondary endpoints such as weight loss, serum lipid levels, blood pressure, renal function, and other parameters. While patient compliance with lifestyle modifications post-bariatric surgery is linked to weight loss outcomes, there are no studies to date that directly evaluate the role of lifestyle modifications and T2DM medication adherence in the management of T2DM post-bariatric surgery. Bariatric surgery is an effective treatment option to achieve long-term weight loss and resolution of obesity-related medical comorbidities, specifically T2DM. Patient compliance to lifestyle modifications post-bariatric surgery is linked to weight loss outcomes and comorbidity resolution. The role of diabetic care compliance in bariatric patient outcomes, however, is poorly understood. Further studies are needed to elucidate the predictors and associated risk factors for non-compliance in this patient population.

Will medications that mimic gut hormones or target their receptors eventually replace bariatric surgery?

Bariatric surgery is currently the most effective therapeutic modality through which sustained beneficial effects on weight loss and metabolic improvement are achieved. During recent years, indications for bariatric surgery have been expanded to include cases of poorly controlled type 2 (T2DM) diabetes mellitus in lesser extremes of body weight. A spectrum of the beneficial effects of surgery is attributed to robust changes of postprandial gut peptide responses that are observed post operatively. Consolidated knowledge regarding gut peptide physiology as well as emerging new evidence shedding light on the mode of action of previously overlooked gut hormones provide appealing potential obesity and T2DM therapeutic perspectives. The accumulation of evidence from the effect of exogenous administration of native gut peptides alone or in combinations to humans as well as the development of mimetic agents exerting agonistic effects on combinations of gut hormone receptors pave the way for future integrated gut peptide-based treatments, which may mimic the effects of bariatric surgery.

High dose vitamin D supplementation does not rescue bone loss following Roux-en-Y gastric bypass in female rats

Postoperative bone loss and increased fracture risk associated with Roux-en-Y gastric bypass (RYGB) have been attributed to vitamin D/calcium malabsorption and resultant secondary hyperparathyroidism (HPT). Adequate vitamin D supplementation (VDS), particularly in an older female population, reduces incidence of secondary HPT but the effect on bone loss and fracture risk remains unclear. To investigate whether VDS corrects the RYGB bone phenotype, 41 obese adult female rats were randomized to RYGB with 1000 IU (R1000) or 5000 IU (R5000) vitamin D/kg food or a sham surgical procedure with either paired (PF) or ad libitum (AL) feeding. Bone turnover markers, urinary calcium/creatinine ratio (CCR), and serum calciotropic and gut hormones were assessed throughout a 14-week postoperative period. Femurs were analyzed by micro-computed tomography (μCT), three-point bending test, and histomorphometry. 1000 IU animals had low 25‑hydroxyvitamin D (25(OH)D), high serum parathyroid hormone (PTH), and very low urine CCR levels. 5000 IU corrected the 25(OH)D and secondary HPT but did not increase urine CCR or serum levels of 1,25‑dihydroxyvitamin D (1,25(OH)D) significantly between RYGB groups. Compared to sham animals at 14 weeks, RYGB animals had significantly higher serum osteocalcin (OCN) and C-terminal telopeptide (CTX) levels. The gut hormone peptide tyrosine tyrosine hormone (PYY) was higher in the RYGB groups, and leptin was lower. μCT and biomechanical testing revealed RYGB females had decreased cortical and trabecular bone volume and weaker, stiffer bone than controls. Histomorphometry showed decreased bone volume and increased osteoid volume with increased mineral apposition rate in RYGB compared to controls. No differences in bone phenotype were identified between 1000 IU and 5000 IU groups, and osteoclast numbers were comparable across all four groups. Thus, in our model, 5000 IU VDS corrected vitamin D deficiency and secondary HPT but did not rescue RYGB mineralization rate nor the osteomalacia phenotype. Longer studies in this model are required to evaluate durability of these detrimental effects. Our findings not only underscore the importance of lifelong repletion of both calcium and vitamin D but also suggest that additional factors affect skeletal health in this population.

Perioperative changes in prouroguanylin hormone response in severely obese subjects after bariatric surgery

BACKGROUND

Prouroguanylin is a gut hormone converted into uroguanylin in the hypothalamus. Uroguanylin induces satiety through guanylyl-cyclase-2C receptor signaling. However, little is known about the role of this hormone in regulating human food intake.

METHODS

In prospective-cohort study, prouroguanylin profile changes were determined during meal stimulation in obese patients 2 weeks before and 2 weeks after Roux-en-Y gastric bypass surgery. We also investigated whether these changes play a role in the anorexigenic effect of Roux-en-Y gastric bypass.

RESULTS

The study enrolled 8 healthy lean volunteers and 10 obese patients with type 2 diabetes. Prouroguanylin levels were postprandially decreased at 30 minutes (P = .04) and 60 minutes (P = .008) in obese patients before surgery, and they were increased at 60 minutes (P = .003), 90 minutes (P = .008), and 120 minutes (P = .009) after surgery. We observed a significant difference (P = .001) in fasting prouroguanylin levels before (8.82 ± 1.2 ng/mL) and after (6.05 ± 1.2 ng/mL) Roux-en-Y gastric bypass. Hunger ratings in the fasted state did not change after Roux-en-Y gastric bypass. Instead, subjects demonstrated significantly (P = .01) lower hunger visual analog scale scores than before Roux-en-Y gastric bypass. No correlations between circulating prouroguanylin levels and hunger perception were found before or after Roux-en-Y gastric bypass.

CONCLUSION

Prouroguanylin levels decrease after meal stimulation in obese patients, and they increase after Roux-en-Y gastric bypass, but no correlations exist with hunger visual analog scale scores.

Metabolic adaptations during negative energy balance and their potential impact on appetite and food intake

This review examines the metabolic adaptations that occur in response to negative energy balance and their potential putative or functional impact on appetite and food intake. Sustained negative energy balance will result in weight loss, with body composition changes similar for different dietary interventions if total energy and protein intake are equated. During periods of underfeeding, compensatory metabolic and behavioural responses occur that attenuate the prescribed energy deficit. While losses of metabolically active tissue during energy deficit result in reduced energy expenditure, an additional down-regulation in expenditure has been noted that cannot be explained by changes in body tissue (e.g. adaptive thermogenesis). Sustained negative energy balance is also associated with an increase in orexigenic drive and changes in appetite-related peptides during weight loss that may act as cues for increased hunger and food intake. It has also been suggested that losses of fat-free mass (FFM) could also act as an orexigenic signal during weight loss, but more data are needed to support these findings and the signalling pathways linking FFM and energy intake remain unclear. Taken together, these metabolic and behavioural responses to weight loss point to a highly complex and dynamic energy balance system in which perturbations to individual components can cause co-ordinated and inter-related compensatory responses elsewhere. The strength of these compensatory responses is individually subtle, and early identification of this variability may help identify individuals that respond well or poorly to an intervention.

Frequency of Hypoglycaemia after Different Bariatric Surgical Procedures

OBJECTIVES

The frequency of postprandial hypoglycaemia after different operative procedures of bariatric surgery (BS) is unknown, although this complication is potentially dangerous. Predictors and severity of hypoglycaemia after Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy, and gastric banding were investigated in a large prospective study.

METHODS

This study was performed at an excellence centre for BS at a tertiary care institution. Data of 333 patients (mean BMI: 44.9 ± 9.6 kg/m2; mean age: 40 ± 10 years; 80.7% women) were analysed in a prospective study with a 2-year observation period after BS. All patients underwent a 2-hour oral glucose tolerance test (OGTT) with measurements of blood glucose (BG) and insulin. For the purpose of this study, hypoglycaemia was defined as a post-challenge BG <2.8 mmol/L during the OGTT.

RESULTS

72 (25.6%) of 281 patients showed post-challenge hypoglycaemia after surgery. Hypoglycaemia was different after various procedures: 32.6% of patients after RYGB, 22.6% after sleeve gastrectomy, but only 2.3% after gastric banding had hypoglycaemia. In the whole group, patients with hypoglycaemia had lost more weight (p = 0.013), had a slightly greater decrease in BMI (p = 0.037), a greater change in 2-hour post-challenge BG (p = 0.001), and a smaller change in 1-hour post-challenge insulin (p = 0.004) compared to patients without hypoglycaemia.

CONCLUSION

This prospective study shows a higher prevalence of severe hypoglycaemia (25.6%) after BS than anticipated from retrospective registers. A systematic evaluation of glucose and insulin levels by OGTT 2 years post-surgery may help to identify patients at increased risk for symptomatic and asymptomatic hypoglycaemia.

Food Intake and Eating Behavior After Bariatric Surgery

Obesity is an escalating global chronic disease. Bariatric surgery is a very efficacious treatment for obesity and its comorbidities. Alterations to gastrointestinal anatomy during bariatric surgery result in neurological and physiological changes affecting hypothalamic signaling, gut hormones, bile acids, and gut microbiota, which coalesce to exert a profound influence on eating behavior. A thorough understanding of the mechanisms underlying eating behavior is essential in the management of patients after bariatric surgery. Studies investigating candidate mechanisms have expanded dramatically in the last decade. Herein we review the proposed mechanisms governing changes in eating behavior, food intake, and body weight after bariatric surgery. Additive or synergistic effects of both conditioned and unconditioned factors likely account for the complete picture of changes in eating behavior. Considered application of strategies designed to support the underlying principles governing changes in eating behavior holds promise as a means of optimizing responses to surgery and long-term outcomes.

Changes in gastrointestinal symptoms and food tolerance 6 months following weight loss surgery: associations with dietary changes, weight loss and the surgical procedure

Background

Gastrointestinal (GI) co-morbidity is common in obese patients, but the effect of weight loss surgery on GI symptoms is incompletely elucidated. The aims of the present study were to explore changes in GI symptoms and food tolerance following weight loss surgery and to study whether such changes were associated with dietary modifications and/or the type of surgical procedure [Roux-en-Y Gastric Bypass (RYGB) versus Vertical Sleeve Gastrectomy (VSG)].

Methods

Participants: Patients with morbid obesity scheduled for weight loss surgery.The patients filled in paper-based questionnaires addressing diet, GI symptoms (bloating, pain, satiety, constipation and diarrhea) and food tolerance/quality of alimentation (satisfaction about current food intake, tolerance to specific foods and frequency of vomiting/regurgitation/reflux) 6 months prior to and 6 months after the surgery. Patients with pre-existing major GI co-morbidity or previous major GI surgery were excluded.

Results

Fifty-four patients (RYGB/VSG: 43/11) were included. Constipation and satiety increased and food tolerance decreased significantly after the surgery (all p-values < 0.05). The increase in satiety was significantly more notable after VSG than after RYGB (p < 0.05).The increase in satiety also correlated with an overall reduction in food tolerance (rho: -0.488, p < 0.01). Divergent changes were seen in the frequency of vomiting/regurgitation/reflux, with a decline after RYGB (p = 0.01) and an increase after VSG (p = 0.06). Intakes of energy, macronutrients, fiber and fluid decreased significantly after the surgery (all p-values < 0.05), but did not correlate with the changes in constipation, satiety or food tolerance (all p-values > 0.05). Pre-operatively, total energy intake correlated with bloating and abdominal pain (rho = 0.343 and 0.310 respectively, p < 0.05 for both), but these correlations did not persist 6 months after the surgery (rho = 0.065 and 0.054 respectively, p > 0.05 for both).

Conclusion

A high caloric intake may explain some of the GI symptoms experienced by non-operated obese patients. The worsening or new-onset of symptoms post-surgery is likely due to anatomical or physiological alterations following surgery. The increase in satiety and the decrease in food tolerance are likely explained by the restrictive nature of the surgeries, as satiety increased more after VSG than after RYGB and correlated with an overall reduction in food tolerance.

Intestinal and Gastric Origins for Diabetes Resolution After Bariatric Surgery

PURPOSE OF REVIEW

This paper will review the intestinal and gastric origins for diabetes resolution after bariatric surgery.

RECENT FINDINGS

In addition to the known metabolic effects of changes in the gut hormonal milieu, more recent studies investigating the role of the microbiome and bile acids and changes in nutrient sensing mechanisms have been shown to have glycemic effects in human and animal models. Independent of weight loss, there are multiple mechanisms that may lead to amelioration or resolution of diabetes following bariatric surgery. There is abundant evidence pointing to changes in gut hormones, bile acids, gut microbiome, and intestinal nutrient sensing; more research is needed to clearly delineate their role in regulating energy and glucose homeostasis after bariatric surgery.

Comparison of consumption behavior and appetite sensations among patients with type 2 diabetes mellitus after bariatric surgery

BACKGROUND

The promising postsurgical weight loss and remission of type 2 diabetes (T2D) from bariatric surgery can be attributed to modified eating physiology after surgical procedures. We sought to investigate the changes in the parameters of consumption behaviors and appetite sensations induced by a mixed meal tolerance test, and to correlate these alterations with age, body mass index, C-peptide levels, and duration of T2D 1 year after bariatric surgery.

METHODS

A total of 16 obese patients with T2D who underwent mini-gastric bypass (GB) and 16 patients who underwent sleeve gastrectomy (SG) were enrolled in this study and evaluated using a mixed meal tolerance test one year after surgery. A visual analogue scale was used for scoring appetite sensation at different time points. The area under the curve (AUC) and the incremental or decremental AUC (ΔAUC) were compared between the two groups.

RESULTS

One year after surgery, a decreasing trend in the consumption time was observed in the GB group compared to the SG group, while the duration of T2D before surgery was negatively correlated with the post-operative consumed time in those after GB. Patients who underwent GB had significantly higher fasting scores for fullness and desire to eat, higher AUC_0'-180' of scores for desire to eat, as well as more effective post-meal suppression of hunger and desire to eat compared with those undergoing SG one year after surgery. Post-operative C-peptide levels were negatively correlated with ΔAUC_0'-180' for hunger and ΔAUC_0'-180' for desire to eat in the GB group, while negatively correlated with ΔAUC_0'-180' for fullness in the SG group.

DISCUSSION

Patients with T2D after either GB or SG exhibit distinct nutrient-induced consumption behaviors and appetite sensations post-operatively, which may account for the differential effects on weight loss and glycemic control after different surgery.

Early effects of Roux-en-Y gastric bypass on peptides and hormones involved in the control of energy balance

INTRODUCTION

Body weight varies depending on the prevailing direction of environmental pressures; however, physiological factors also play a significant role in the control of body weight. The aim of the present study was to assess the impact of Roux-en-Y gastric bypass (RYGB) on hormones and peptides involved in the control of energy balance and their possible implications in appetite/satiety.

METHODS

The sample included 39 individuals with extreme obesity (37 women and two men) who underwent RYGB. Anthropometric and biochemical markers were collected before surgery and 6 months after RYGB.

RESULTS

The BMI decreased from 44.3±6.4 to 31.7±5.7 kg/m (P<0.001) at the sixth month. Percentage of excess weight lost was 63.2±25.0%. Leptin and glucose levels decreased significantly 6 months after RYGB (P<0.001). Interestingly, a significant correlation was confirmed between the anorexigenic gut hormone peptide YY (PYY) and the central anorexigenic mediator α-melanocyte-stimulating hormone after 6 months of RYGB (r=0.35, P=0.004). In contrast, PYY concentrations were correlated negatively with BMI (r=-0.34, P=0.002).

CONCLUSION

In the present investigation, it was found that there is a relationship between α-melanocyte-stimulating hormone and PYY concentrations, and it supports the role of the PYY to POMC signal in appetite regulation after RYGB.

Bariatric surgery and nonalcoholic fatty liver disease

The rising prevalence of nonalcoholic fatty liver disease (NAFLD) is associated with the increasing global pandemic of obesity. These conditions cluster with type II diabetes mellitus and the metabolic syndrome to result in obesity-associated liver disease. The benefits of bariatric procedures on diabetes and the metabolic syndrome have been recognized for some time, and there is now mounting evidence to suggest that bariatric procedures improve liver histology and contribute to the beneficial resolution of NAFLD in obese patients. These beneficial effects derive from a number of weight-dependent and weight-independent mechanisms including surgical BRAVE actions (bile flow changes, restriction of stomach size, anatomical gastrointestinal rearrangement, vagal manipulation, enteric hormonal modulation) and subsequent effects such as reduced lipid intake, adipocytokine secretion, modulation of gut flora, improvements in insulin resistance and reduced inflammation. Here, we review the clinical investigations on bariatric procedures for NAFLD, in addition to the mounting mechanistic data supporting these findings. Elucidating the mechanisms by which bariatric procedures may resolve NAFLD can help enhance surgical approaches for metabolic hepatic dysfunction and also contribute toward developing the next generation of therapies aimed at reducing the burden of obesity-associated liver disease.

Effects of lifestyle interventions that include a physical activity component in class II and III obese individuals: a systematic review and meta-analysis

BACKGROUND

In class II and III obese individuals, lifestyle intervention is the first step to achieve weight loss and treat obesity-related comorbidities before considering bariatric surgery. A systematic review, meta-analysis, and meta-regression were performed to assess the impact of lifestyle interventions incorporating a physical activity (PA) component on health outcomes of class II and III obese individuals.

METHODS

An electronic search was conducted in 4 databases (Medline, Scopus, CINAHL and Sportdiscus). Two independent investigators selected original studies assessing the impact of lifestyle interventions with PA components on anthropometric parameters, cardiometabolic risk factors (fat mass, blood pressure, lipid and glucose metabolism), behaviour modification (PA and nutritional changes), and quality of life in adults with body mass index (BMI) ≥ 35 kg/m2. Estimates were pooled using a random-effect model (DerSimonian and Laird method). Heterogeneity between studies was assessed by the Cochran's chi-square test and quantified through an estimation of the I².

RESULTS

Of the 3,170 identified articles, 56 met our eligibility criteria, with a large majority of uncontrolled studies (80%). The meta-analysis based on uncontrolled studies showed significant heterogeneity among all included studies. The pooled mean difference in weight loss was 8.9 kg (95% CI, 10.2-7.7; p < 0.01) and 2.8 kg/m² in BMI loss (95% CI, 3.4-2.2; p < 0.01). Long-term interventions produced superior weight loss (11.3 kg) compared to short-term (7.2 kg) and intermediate-term (8.0 kg) interventions. A significant global effect of lifestyle intervention on fat mass, waist circumference, blood pressure, total cholesterol, LDL-C, triglycerides and fasting insulin was found (p<0.01), without significant effect on HDL-C and fasting blood glucose.

CONCLUSIONS

Lifestyle interventions incorporating a PA component can improve weight and various cardiometabolic risk factors in class II and III obese individuals. However, further high quality trials are needed to confirm this evidence, especially beyond weight loss.

Roux-en-Y gastric bypass: effects on feeding behavior and underlying mechanisms

Bariatric surgery is the most effective treatment for severe obesity, producing marked sustained weight loss with associated reduced morbidity and mortality. Roux-en-Y gastric bypass surgery (RYGBP), the most commonly performed procedure, was initially viewed as a hybrid restrictive-malabsorptive procedure. However, over the last decade, it has become apparent that alternative physiologic mechanisms underlie its beneficial effects. RYGBP-induced altered feeding behavior, including reduced appetite and changes in taste/food preferences, is now recognized as a key driver of the sustained postoperative weight loss. The brain ultimately determines feeding behavior, and here we review the mechanisms by which RYGBP may affect central appetite-regulating pathways.

Pharmacological Management of the Obese Patient

Being obese goes beyond moral failure or a character flaw. Obesity has the defining characteristics of a chronic disease for which there is no cure. Treatment may require lifelong treatment which may include pharmacotherapy. Experience with long term use of obesity drugs is limited but evidence suggests that pharmacotherapy can improve patient outcomes and patient outlook. With current obesity drugs, weight loss is usually modest but clinically significant satisfying the FDA threshold for drug effectiveness. This weight loss is associated with clinically significant improvements in many obesity co morbidities and risk factors and could eliminate some risk factors with continued use. When used in conjunction with a comprehensive program for weight management, obesity drugs can reduce appetite or hunger, increase satiety, provide improved control over aberrant eating behaviors and modify food seeking behaviors. Pharmacotherapy can enhance weight loss and compliance during the periods of weight loss and in maintaining that weight loss, increasing physical activity and may enhance a focus on making life long changes.

This article will discuss mechanisms of action of obesity drugs, theories of altered body defense of body weight, Food and Drug Administration (FDA) approved obesity drugs, and off-label use of FDA approved drugs. The value of over-the counter (OTC) medications and diet supplements, as well as fat substitutes in the treatment of obesity drugs will be explored. Obesity drugs awaiting FDA approval and compounds under development will be reviewed. The section on approaches to drug management will include clinical considerations for; who should receive pharmacotherapy and when, length of treatment and drug discontinuation, weight regain and the role of pharmacotherapy.

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.

Differential effects of laparoscopic sleeve gastrectomy and laparoscopic gastric bypass on appetite, circulating acyl-ghrelin, peptide YY3-36 and active GLP-1 levels in non-diabetic humans

Laparoscopic Roux-en-Y gastric bypass (LRYGBP) reduces appetite and induces significant and sustainable weight loss. Circulating gut hormones changes engendered by LRYGBP are implicated in mediating these beneficial effects. Laparoscopic sleeve gastrectomy (LSG) is advocated as an alternative to LRYGBP, with comparable short-term weight loss and metabolic outcomes. LRYGBP and LSG are anatomically distinct procedures causing differential entero-endocrine cell nutrient exposure and thus potentially different gut hormone changes. Studies reporting the comparative effects of LRYGBP and LSG on appetite and circulating gut hormones are controversial, with no data to date on the effects of LSG on circulating peptide YY3-36 (PYY3-36) levels, the specific PYY anorectic isoform. In this study, we prospectively investigated appetite and gut hormone changes in response to LRYGBP and LSG in adiposity-matched non-diabetic patients. Anthropometric indices, leptin, fasted and nutrient-stimulated acyl-ghrelin, active glucagon-like peptide-1 (GLP-1), PYY3-36 levels and appetite were determined pre-operatively and at 6 and 12 weeks post-operatively in obese, non-diabetic females, with ten undergoing LRYGBP and eight adiposity-matched females undergoing LSG. LRYGBP and LSG comparably reduced adiposity. LSG decreased fasting and post-prandial plasma acyl-ghrelin compared to pre-surgery and to LRYGBP. Nutrient-stimulated PYY3-36 and active GLP-1 concentrations increased post-operatively in both groups. However, LRYGBP induced greater, more sustained PYY3-36 and active GLP-1 increments compared to LSG. LRYGBP suppressed fasting hunger compared to LSG. A similar increase in post-prandial fullness was observed post-surgery following both procedures. LRYGBP and LSG produced comparable enhanced satiety and weight loss. However, LSG and LRYGBP differentially altered gut hormone profiles.

Gastric bypass and sleeve gastrectomy for type 2 diabetes: a systematic review and meta-analysis of outcomes

Bariatric surgery is effective in the management of type 2 diabetes (T2D) and obesity; however, it is not clear whether Roux-en-Y gastric bypass (GBP) or sleeve gastrectomy (SG) is the most effective procedure. This review compared T2D remission and weight loss in patients with T2D after GBP or SG. All human SG or GBP studies published in English between 1 Jan 2007 and 30 April 2012 reporting on BMI and T2D outcomes were included. Analyses were performed separately for the most frequent distinct time points reported after surgery. A total of 21 prospective (three randomised control trials) and 12 retrospective studies, involving 1375 patients met eligibility criteria. T2D remission defined by hemoglobin A1c of <6.5 % for GBP and SG respectively was 67 and 56 % at 3 months, 76 and 68 % at 12 months, and 81 and 80 % at 36 months. Greater percent excess BMI loss occurred at 12 months (72.5 % after GBP and 66.7 % after SG) compared with 3 months (45.9 % after GBP and 25.9 % after SG). There was no significant difference in either T2D remission or weight loss with GBP compared with SG. Both GBP and SG result in similar early remission of T2D in 67 and 56 % of patients at 3 months respectively with modest additional T2D remission with time, although weight loss with both procedures increase substantially between 3 and 12 months post-operatively. Further randomised controlled trials comparing SG and GBP in patients with T2D using comparable definitions of diabetes remission with long-term follow-up are needed to evaluate relative benefits.

Feeding and bone turnover in gastric bypass

CONTEXT

Roux-en-Y gastric bypass (RYGB) is associated with high bone turnover. In healthy subjects, feeding causes acute reduction of bone resorption, which is regulated by several intestinal and pancreatic peptides.

OBJECTIVE

Our objective was to assess bone turnover after feeding in patients with RYGB.

DESIGN AND SETTING

This was a cross-sectional case-control study at a university hospital.

PARTICIPANTS

Fifteen postmenopausal women who underwent RYGB 7.4 ± 4.1 years previously were matched by age and body mass index with 15 nonoperated women (controls).

MAIN OUTCOMES

Serum PTH, calcium, phosphorus, insulin, carboxy telopeptide (CTX), procollagen type I N-terminal propeptide (P1NP), and glucagon-like peptide 2 (GLP-2) were measured while fasting and after a standard meal (SM).

RESULTS

The fasting calcium, phosphorus, and PTH were similar in both groups and exhibited similar decreases after an SM. The fasting CTX level was higher in the RYGB than in the control group (0.589 ± 0.18 vs 0.382 ± 0.11 ng/mL; P < .05) and fell to a nadir of 42.2% of the basal value in the RYGB and 53.9% in controls (P < .05). The fasting and postprandial P1NP levels were similar in both groups and fell to a nadir of 85.8% in the RYGB and 89.3% in controls. Insulin and GLP-2 levels were similar during fasting in both groups. RYGB patients had exaggerated postprandial insulin and GLP-2 response compared with the controls with the insulin and GLP-2 area under the curve being significantly higher in the RYGB group. There was a significant negative correlation between the peak of insulin levels and the CTX changes.

CONCLUSION

The acute reduction in bone resorption after feeding is preserved in RYGB and is even higher than in nonoperated subjects. This phenomenon is related to the increase of postprandial levels of insulin. These findings suggest a bone-protecting mechanism in RYGB that may counteract the elevated bone resorption that occurs during fasting.

Gastric bypass in obese rats causes bone loss, vitamin D deficiency, metabolic acidosis, and elevated peptide YY

BACKGROUND

Metabolic bone disease and bariatric surgery have long been interconnected. The objective of this study is to better understand the mechanisms of bone mass loss after Roux-en-Y gastric bypass (RYGB) surgery. We evaluated mineral homeostasis and bone mass in diet-induced obese (DIO) rats after RYGB or sham surgery.

METHODS

Twelve DIO male Sprague Dawley rats underwent RYGB (n = 8) or sham (n = 4) surgery at 21 weeks of age. Postoperatively, animals ate an ad libitum 40% fat, normal calcium diet and were euthanized 22 weeks later. Serum and urine chemistries, insulin, leptin, bone turnover markers (BTM), and calciotropic and gut hormones were measured before and 22 weeks after surgery. Femurs were analyzed using microcomputed tomography (µCT).

RESULTS

Compared to sham, RYGB animals had lower serum bicarbonate, calcium, 25-hydroxyvitamin D, insulin, and leptin levels with higher serum parathyroid hormone, peptide YY, and urinary calcium at 43 weeks of age. Sham control rats gained weight and had coupled decreases in formation (P1NP and OC) and unchanged resorption (CTX) BTMs. Comparatively, RYGB animals had higher serum CTX and OC but even lower P1NP levels than controls. µCT revealed lower trabecular bone volume, number, and thickness and lower cortical bone volume, thickness, and moment of inertia relative to controls.

CONCLUSION

In rats with DIO, long-term RYGB-associated bone resorption appears to be driven in part by vitamin D malabsorption and secondary hyperparathyroidism. Other mechanisms, such as chronic acidosis, changes in fat-secreted hormones, and persistently elevated gut-derived hormone peptide YY, may also contribute to observed bone mass differences. Further investigation of these potential contributors to bone loss may lead to new targets for skeletal maintenance after RYGB.

Remodeling intestinal flora with sleeve gastrectomy in diabetic rats

OBJECTIVE

As a complicated symbiotic system, intestinal flora is reported closely related to the development of type 2 diabetes recently. Sleeve gastrectomy is one of the approaches of bariatric surgery and could improve blood glucose control in type 2 diabetes patients. This study was to explore the relationship between remodeled intestinal flora and glucose metabolism in diabetic rats.

METHODS

20 male diabetic rats were operated; 10 of them underwent sleeve gastrectomy, and 10 of them underwent sham operation. Meanwhile 10 male normal rats underwent sleeve gastrectomy as control. The animals' weight and FBG had been measured. The composition changes of intestinal flora were detected by 16S rDNA sequence analysis.

RESULTS

In diabetic rats, weight and fasting blood glucose decreased significantly after sleeve gastrectomy. However, there was no significant change for weight and blood glucose in normal rats after operation. The intestinal flora of diabetic rats reduced in the proportion of Firmicutes and increased in the proportion of Bacteroidetes after sleeve gastrectomy.

CONCLUSION

The change of dominant microorganisms in intestinal flora might play an important role in the glucose metabolism.

Mineral malnutrition following bariatric surgery

Moderate/severe obesity is on the rise in the United States. Weight management includes bariatric surgery, which is effective and can alleviate morbidity and mortality from obesity-associated diseases. However, many individuals are dealing with nutritional complications. Risk factors include: 1) preoperative malnutrition (e.g., vitamin D, iron); 2) decreased food intake (due to reduced hunger and increased satiety, food intolerances, frequent vomiting); 3) inadequate nutrient supplementation (due to poor compliance with multivitamin/multimineral regimen, insufficient amounts of vitamins and/or minerals in supplements); 4) nutrient malabsorption; and 5) inadequate nutritional support (due to lack of follow-up, insufficient monitoring, difficulty in recognizing symptoms of deficiency). For some nutrients (e.g., protein, vitamin B-12, vitamin D), malnutrition issues are reasonably addressed through patient education, routine monitoring, and effective treatment strategies. However, there is little attention paid to other nutrients (e.g., zinc, copper), which if left untreated may have devastating consequences (e.g., hair loss, poor immunity, anemia, defects in neuro-muscular function). This review focuses on malnutrition in essential minerals, including calcium (and vitamin D), iron, zinc, and copper, which commonly occur following popular bariatric procedures. There will be emphasis on the complexities, including confounding factors, related to screening, recognition of symptoms, and, when available, current recommendations for treatment. There is an exceptionally high risk of malnutrition in adolescents and pregnant women and their fetuses, who may be vulnerable to problems in growth and development. More research is required to inform evidence-based recommendations for improving nutritional status following bariatric surgery and optimizing weight loss, metabolic, and nutritional outcomes.

Gastrointestinal hormones and bariatric surgery-induced weight loss

Obesity continues to be a major public health problem in the United States and worldwide. While recent statistics have demonstrated that obesity rates have begun to plateau, more severe classes of obesity are accelerating at a faster pace with important implications in regards to treatment. Bariatric surgery has a profound and durable effect on weight loss, being to date one of the most successful interventions for obesity.

OBJECTIVE

To provide updates to the possible role of gut hormones in post bariatric surgery weight loss and weight loss maintenance.

DESIGN AND METHODS

The current review examines the changes in gastro-intestinal hormones with bariatric surgery and the potential mechanisms by which these changes could result in decreased weight and adiposity.

RESULTS

The mechanism by which bariatric surgery results in body weight changes is incompletely elucidated, but it clearly goes beyond caloric restriction and malabsorption.

CONCLUSION

Changes in gastro-intestinal hormones, including increases in GLP-1, PYY, and oxyntomodulin, decreases in GIP and ghrelin, or the combined action of all these hormones might play a role in induction and long-term maintenance of weight loss.

Mechanisms of weight loss, diabetes control and changes in food choices after gastrointestinal surgery

The long-term effects of lifestyle changes, diet and medical therapy on obesity are limited. Bariatric surgery is the most effective long-term treatment with the greatest chances for amelioration of obesity-associated complications, including type 2 diabetes mellitus (T2DM). There is increasing evidence in the literature that bariatric operations have a profound effect on human physiology, by reducing hunger, increasing satiety, paradoxically increasing energy expenditure, and even promoting healthy food preferences. Some of these operations improve glucose homeostasis in patients with T2DM independently of weight loss. Changes in the gut hormone levels of glucagon-like peptide 1, peptide YY and ghrelin have been proposed as some of the mediators implicated in changing physiology. The aim of this review is to critically explore the current knowledge on the putative mechanisms of the change in weight and improvement in T2DM glycaemic control after the most commonly performed bariatric operations.

Alterations in gut hormones after laparoscopic sleeve gastrectomy: a prospective clinical and laboratory investigational study

OBJECTIVE

To evaluate the effect of laparoscopic sleeve gastrectomy (LSG) on fasting and meal-stimulated release of the gut hormones ghrelin, pancreatic polypeptide (PP), peptide-YY (PYY), glucagon-like peptide-1 (GLP-1), and amylin and of the adipocytokine leptin.

BACKGROUND

Mounting evidence suggests that the mechanisms of weight loss and the improvement in glucose metabolism seen after LSG are related not only to gastric restriction but also to neurohormonal changes.

METHODS

: Fasting and postprandial levels at 60 and 120 minutes after a standard test meal of the above peptides and glucose metabolism indices were evaluated in 15 consecutive morbidly obese (MO) subjects before and 6 and 12 months after LSG. As study controls, 15 lean subjects matched for age and sex were also assessed.

RESULTS

Body mass index values notably decreased at 6 and 12 months (P < 0.01), postoperatively. In addition, an overall improvement of the glycemic profile of MO patients was noted. After LSG, markedly decreased fasting and postprandial levels of ghrelin, amylin, and leptin were observed. A significant postprandial increase of PYY and GLP-1 levels was also noted postoperatively. Interestingly, significantly increased levels of PP were noted only at 60 minutes postprandially after LSG.

CONCLUSIONS

LSG markedly improved glucose homeostasis and generated significant changes in ghrelin, PP, PYY, GLP-1, amylin, and leptin levels. These multiple hormonal actions may have several beneficial effects on the underlying mechanism of weight loss, demonstrating that LSG could be more than just a restrictive bariatric operation.

Bariatric surgery, bone loss, obesity and possible mechanisms

Bariatric surgery remains the most effective treatment for severely obese patients. However, the potential long-term effects of bariatric surgical procedures on health, including bone health, are only partially understood. The goal of this review was to present data on the impact of bariatric surgery on bone metabolism and to analyse possible reasons for the loss of bone mass that frequently occurs after bariatric surgery. Such factors include nutritional deficiencies, rapid weight loss per se, effects of fat-derived adipokines and gut-derived appetite-regulatory hormones. However, the relative roles of these factors in skeletal regulation and the mechanisms by which they work are not yet fully defined. Our review was focussed on the complex relationship between body weight, fat mass and bone mass, as well as peripheral and central mediators potentially involved in the dual regulation of both energy and bone homeostasis. We also review the data on the inverse relationship between central obesity, bone marrow fat and osteoporosis. As the number of bariatric operations increases, it is imperative to recognize mechanisms responsible for bariatric surgery-induced bone loss, with careful monitoring of bone health including long-term fracture incidence in patients undergoing these procedures.

Effect of vertical sleeve gastrectomy on food selection and satiation in rats

Vertical sleeve gastrectomy (VSG) is a restrictive procedure that reduces food intake to produce weight loss. Here we assess volume and nutrient effects on the ingestive behavior of VSG and sham surgery animals. Rats given access to Ensure or pelleted chow were used to determine if liquid foods would adversely affect weight loss after surgery. Volume effects were studied by altering the caloric density of Ensure, and dietary preferences for fat and carbohydrate (sucrose) were assessed using a two-bottle test. c-Fos was used to measure neuronal activation in the nucleus of the solitary tract and area postrema in response to intragastric infusions of water, sucrose, or Intralipid. The degree of colocalization with catecholaminergic neurons was also assessed. VSG rats did not show the expected preference for a liquid diet over chow and lacked dietary preferences for fat seen in shams. Preferences for carbohydrate/sucrose solutions were unaffected by surgery. Meal size was reduced by VSG; however, VSG rats were able to alter their volume of intake to compensate for changes in caloric density, and intragastric infusions of water produced similar levels of neuronal activation among VSG, sham, and pair-fed rats. In comparison, nutrient-induced c-Fos activation was substantially increased by VSG. Colocalization between c-Fos and catecholaminergic-expressing neurons was similar among rats treated with water, sucrose, or Intralipid. VSG alters nutrient sensing in a manner that lowers the threshold for satiety and reduces fat preference to induce and maintain weight loss.

Laparoscopic sleeve gastrectomy as a stand-alone procedure for morbid obesity: report of 1,000 cases and 3-year follow-up

BACKGROUND

Laparoscopic sleeve gastrectomy (LSG) is an emerging surgical technique with encouraging results. The objective of this study is to report surgical results after 1,000 consecutive LSG cases as a stand-alone procedure for morbid obesity during a 3-year follow-up.

METHODS

Data were obtained by review of our prospectively maintained database, patients' clinical charts, and phone interview of all patients who underwent LSG in our institution from December 2005 to February 2010.

RESULTS

There were 773 (77.3%) women whose preoperative age and BMI was 36.9 ± 11.5 years and 37.4 ± 4.0 kg/m(2), respectively. The most common co-morbid conditions were insulin resistance 55.1%, dyslipidemia 45.5%, arterial hypertension 23.1%, hypothyroidism 15.4% and non-alcoholic fatty liver disease 12%. Excess weight loss was as follows: 1 year 86.6%, 2 years 84.1%, and 3 years 84.5%. Early and late complications occurred in 34 (3.4%) and 20 (2.0%) patients, respectively. Reoperation was required in seven (0.7%) patients. There was no mortality during follow-up.

CONCLUSIONS

LSG seems to be a safe and effective surgical technique for morbid obesity as a stand-alone procedure.

Peptide YY regulates bone remodeling in mice: a link between gut and skeletal biology

Background & Aims

Gastrointestinal peptides are increasingly being linked to processes controlling the maintenance of bone mass. Peptide YY (PYY), a gut-derived satiety peptide of the neuropeptide Y family, is upregulated in some states that also display low bone mass. Importantly, PYY has high affinity for Y-receptors, particularly Y1R and Y2R, which are known to regulate bone mass. Anorexic conditions and bariatric surgery for obesity influence circulating levels of PYY and have a negative impact on bone mass, but the precise mechanism behind this is unclear. We thus examined whether alterations in PYY expression affect bone mass.

Methods

Bone microstructure and cellular activity were analyzed in germline PYY knockout and conditional adult-onset PYY over-expressing mice at lumbar and femoral sites using histomorphometry and micro-computed tomography.

Results

PYY displayed a negative relationship with osteoblast activity. Male and female PYY knockout mice showed enhanced osteoblast activity, with greater cancellous bone mass. Conversely, PYY over-expression lowered osteoblast activity in vivo, via a direct Y1 receptor mediated mechanism involving MAPK stimulation evident in vitro. In contrast to PYY knockout mice, PYY over expression also altered bone resorption, as indicated by greater osteoclast surface, despite the lack of Y-receptor expression in osteoclastic cells. While evident in both sexes, cellular changes were generally more pronounced in females.

Conclusions

These data demonstrate that the gut peptide PYY is critical for the control of bone remodeling. This regulatory axis from the intestine to bone has the potential to contribute to the marked bone loss observed in situations of extreme weight loss and higher circulating PYY levels, such as anorexia and bariatric obesity surgery, and may be important in the maintenance of bone mass in the general population.

Role of Gut-Related Peptides and Other Hormones in the Amelioration of Type 2 Diabetes after Roux-en-Y Gastric Bypass Surgery

Bariatric surgery is currently the most effective and durable therapy for obesity. Roux-en-Y gastric bypass surgery, the most commonly performed procedure worldwide, causes substantial weight loss and improvement in several comorbidities associated with obesity, especially type 2 diabetes. Several mechanisms are proposed to explain the improvement in glucose metabolism after RYGB surgery: the caloric restriction and weight loss per se, the improvement in insulin resistance and beta cell function, and finally the alterations in the various gastrointestinal hormones and adipokines that have been shown to play an important role in glucose homeostasis. However, the timing, exact changes of these hormones, and the relative importance of these changes in the metabolic improvement postbariatric surgery remain to be further clarified. This paper reviews the various changes post-RYGB in adipokines and gut peptides in subjects with T2D.

Effects of sleeve gastrectomy and medical treatment for obesity on glucagon-like peptide 1 levels and glucose homeostasis in non-diabetic subjects

BACKGROUND

The effects of medical and surgical treatments for obesity on glucose metabolism and glucagon-like peptide 1 (GLP-1) levels independent of weight loss remain unclear. This study aims to assess plasma glucose levels, insulin sensitivity and secretion, and GLP-1 levels before and after sleeve gastrectomy (SG) or medical treatment (MED) for obesity.

METHODS

This study is a prospective, controlled, non-randomised study. Two groups of non-diabetic obese patients with similar BMIs, including a SG group (BMI, 35.5 ± 0.9 kg/m(2); n = 6) and a MED group (BMI, 37.7 ± 1.9 kg/m(2); n = 6) and a group of lean subjects (BMI, 21.7 ± 0.7 kg/m(2); n = 8).

RESULTS

Plasma glucose, insulin, and total GLP-1 levels at fasting and after the intake of a standard liquid meal at baseline and at 2 months post-intervention. At baseline, total GLP-1 levels were similar, but obese patients had lower insulin sensitivity and higher insulin secretion than lean subjects. At 2 months post-intervention, SG and MED patients achieved similar weight loss (14.4 ± 0.8%, 15.3 ± 0.9%, respectively). Insulin sensitivity increased in SG and MED patients; however, postprandial insulin secretion decreased after MED, but not after SG. The incremental area under the curve of GLP-1 increased after SG (P = 0.04), but not after MED.

CONCLUSIONS

Weight loss by medical or surgical treatment improved insulin sensitivity. However, only MED corrected the hyperinsulinemic postprandial state associated to obesity. Postprandial GLP-1 levels increased significantly after SG without duodenal exclusion, which may explain why insulin secretion did not decrease following this surgery.

Surgical treatments for obesity

Bariatric surgery is currently the most effective and durable treatment option for extreme obesity. Restrictive procedures, such as AGB and SG, limit gastric capacity and, thus, food intake while leaving the gastrointestinal tract intact. Malabsorptive procedures, such as BPD, shorten the length of the intestine to decrease nutrient absorption. Combined procedures, such as RYGB, include restriction and gastrointestinal rearrangement. Procedures that bypass segments of the gut are associated with greater weight loss and greater improvements in comorbid conditions than is gastric banding. This may be due, in part, to the differential effects of gastrointestinal rearrangement on the secretion of orexigenic and anorexigenic gut peptides that regulate appetite, glucose homeostasis, and body weight. Bariatric surgery is generally associated with low rates of perioperative and postoperative morbidity and mortality, although rigorous comparative safety data are lacking. High-quality, long-term, randomized, controlled trials are needed to compare the efficacy, safety, and cost effectiveness of the various bariatric surgery procedures with each other, as well as with intensive nonsurgical weight loss interventions.