Ghrelin and apolipoprotein AIV levels show opposite trends to leptin levels during weight loss in morbidly obese patients. Obes Surg. 2009;19:1414-1423. [PMID: 19172368 DOI: 10.1007/s11695-008-9793-3]

An interdisciplinary therapy for lifestyle change is effective in improving psychological and inflammatory parameters in women with grade I obesity

Obesity and depression, disorders associated with inflammation, have high incidences in women. Understanding the derangements present in the initial phase of obesity may point to factors that could help avoiding disease aggravation. The present study aimed at investigating the effects of a 6-months interdisciplinary therapy for weight loss in women with grade I obesity. Before and after the therapy, 37 middle-aged women donated blood and responded to questionnaires for depression and anxiety symptoms. Inflammatory parameters were evaluated in serum and a preliminary screening of the plasma proteome was performed. The therapy decreased anthropometric, psychological scores, and serum levels of inflammatory parameters. Depression and anxiety scores correlated positively with some inflammatory parameters. The proteomic analysis showed changes in proteins related to cholesterol metabolism and inflammatory response. Interdisciplinary therapy improves anthropometric and inflammatory statuses and ameliorating psychological symptoms. The decrease of MCP-1 levels after interdisciplinary therapy has not been reported so far, at the best of our knowledge. The present demonstration of positive associations of inflammatory markers and psychological scores indicate that these mediators may be useful to monitor psychological status in obesity. The present proteome data, although preliminary, pointed to plasma alterations indicative of improvement of inflammation after interdisciplinary therapy.

The Effects of Intermittent Diet Breaks during 25% Energy Restriction on Body Composition and Resting Metabolic Rate in Resistance-Trained Females: A Randomized Controlled Trial

The purpose of this study was to examine the effects of intermittent versus continuous energy restriction on body composition, resting metabolic rate, and eating behaviors in resistance-trained females. Thirty-eight resistance-trained females (mean ± standard deviation age: 22.3±4.2 years) were randomized to receive either six weeks of a continuous 25% reduction in energy intake (n= 18), or one week of energy balance after every two weeks of 25% energy restriction (eight weeks total; n= 20). Participants were instructed to ingest 1.8 g protein/kilogram bodyweight per day and completed three weekly supervised resistance training sessions throughout the intervention. There were no differences between groups for changes over time in body composition, resting metabolic rate, or seven of the eight measured eating behavior variables (p > 0.05). However, a significant group-by-time interaction for disinhibition (p < 0.01) from the Three-Factor Eating Questionnaire was observed, with values (± standard error) in the continuous group increasing from 4.91 ± 0.73 to 6.17 ± 0.71, while values in the intermittent group decreased from 6.80 ± 0.68 to 6.05 ± 0.68. Thus, diet breaks do not appear to induce improvements in body composition or metabolic rate in comparison with continuous energy restriction over six weeks of dieting, but may be employed for those who desire a short-term break from an energy-restricted diet without fear of fat regain. While diet breaks may reduce the impact of prolonged energy restriction on measures of disinhibition, they also require a longer time period that may be less appealing for some individuals.

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.

Metabolic and cardiovascular outcomes of bariatric surgery

PURPOSE OF REVIEW

Bariatric surgery is an effective therapy for morbid obesity that also improves weight-related metabolic parameters and reduces morbidity and mortality. The purpose of this review is to consolidate our current understanding of metabolic, macrovascular and microvascular benefits of bariatric surgery and to provide an update.

RECENT FINDINGS

Early resolution of insulin resistance and type 2 diabetes mellitus (T2DM) varies by type of bariatric surgery and appears to be mediated by changes in secretion of gut hormones, metabolism of bile acids, expression of glucose transporters and the gut microbiome. Dyslipidaemia, atherosclerosis, microvascular complications of obesity and diabetes, systemic and tissue-level inflammation show evidence of regression and hypertension improves significantly after bariatric surgery.

SUMMARY

Bariatric surgery leads to improvements in obesity-related metabolic comorbidities such as dyslipidaemia, HDL functionality, hypertension, T2DM, insulin resistance and inflammation. It slows the atherosclerotic process and reduces cardiovascular and all-cause mortality. Recent data have demonstrated regression of the microvascular complications of obesity and diabetes including the regeneration of small nerve fibres. The magnitude of change in short-term metabolic effects depends on the surgical procedure whilst longer term effects are related to the amount of sustained excess weight loss.

Cardiac remodeling in obesity and after bariatric and metabolic surgery; is there a role for gastro-intestinal hormones?

Introduction: Obesity is associated with various diseases such as type 2 diabetes, hypertension, obstructive sleep apnea syndrome (OSAS), metabolic syndrome, and cardiovascular diseases. It affects several organ systems, including the pulmonary and cardiac systems. Furthermore, it induces pulmonary and cardiac changes that can result in right and/or left heart failure.Areas covered: In this review, authors provide an overview of obesity and cardiovascular remodeling, the individual actions of the gut hormones (like GLP-1 and PYY), the effects after bariatric/metabolic surgery and its influence on cardiac remodeling. In this review, we focussed and searched for literature in Pubmed and The Cochrane library (from the earliest date until April 2019), regarding cardiac function changes before and after bariatric surgery and literature regarding changes in gastrointestinal hormones.Expert opinion: Regarding the surgical treatment of obesity and metabolic diseases there is recognition of the importance of both weight loss (bariatric surgery) and improvement in metabolic milieu (metabolic surgery). A growing body of evidence further suggests that bariatric surgical procedures [like the Sleeve Gastrectomy (SG), Roux-en Y Gastric Bypass (RYGB), or One Anastomosis Gastric Bypass (OAGB)] have can improve outcomes of patients suffering from a number of cardiovascular diseases, including heart failure.

Serum proteome changes and accelerated reduction of fat mass after laparoscopic gastric plication in morbidly obese patients

Laparoscopic Gastric Plication (LGP) is a relatively new bariatric surgical procedure which no part of the stomach is removed. It is not clearly understood how LGP leads to fatty tissue reduction. We aimed to investigate the impact of LGP on serum proteome and understand molecular mechanisms of LGP-induced weight loss post-surgery. A Prospective observational study of 16 obese individuals who underwent LGP was performed. A Label-free quantitative shotgun proteomics approach was used to compare serum proteome of subjects before surgery with serum of the same individuals 1 to 2 months post-surgery (T1) and 4 to 5 months post-surgery (T2). The proteome analysis revealed that 48 proteins were differentially regulated between pre-surgery and T1, and seven proteins between pre-surgery and T2 of which six proteins were shared between the two timepoints. Among differentially regulated proteins, four proteins (SRGN, FETUB, LCP1 and CFP) have not previously been described in the context of BMI/weight loss. Despite few differences following LGP, most regulated serum proteins are in accordance with alternative weight loss procedures. Pathway analysis revealed changes to lipid- and inflammatory pathways, including PPARα/RXRα, LXR/RXR and FXR/RXR activation, especially at T1. At T2, the pathways related to inflammation and immune system are most affected. SIGNIFICANCE: Among the available clinical therapies for morbid obesity, bariatric surgery is considered as the most effective approach to achieve long-term weight loss, alongside a significant improvement in metabolic syndrome. However, very little is known about the underlying mechanism associated with significant weight loss post-surgery. Understanding such mechanisms could lead to development of safer non-surgical weight loss approaches. We here present the first analysis of the impact of LGP on the serum proteome, to bring new insights into the underlying molecular mechanism. Our findings indicate that LGP has a comprehensive systemic effect based on the blood serum proteome profile which might account for accelerated reduction of fat mass after surgery, thus, food restriction is not the only reason for weight loss following this unique surgical approach. As secretory regions of the stomach are preserved in LGP and it is associated with minimal physiological and anatomical changes, the findings are of high importance in the field of bariatric surgery and weight loss.

Glucagon-Like Peptides 1 and 2 Are Involved in Satiety Modulation After Modified Biliopancreatic Diversion: Results of a Pilot Study

BACKGROUND

This paper aimed to evaluate the influence of modified biliopancreatic diversion (BPD) on the levels of GLP-1 and GLP-2 and correlate them with satiety regulation.

METHODS

This is a pilot prospective cohort study that evaluated six mildly obese individuals with type 2 diabetes mellitus, which underwent modified BPD and were followed-up for 12 months. Levels of GLP-1 and GLP-2 after a standard meal tolerance test were determined and correlated with satiety scores obtained by means of a visual analogue scale (VAS).

RESULTS

There were significant changes in BMI (33 ± 2.2 versus 26.3 ± 2.2 kg/m²; p < 0.001), HbA1c (7.9 ± 1.6 versus 5.8 ± 1.2%; p = 0.026), total cholesterol (172.3 ± 11.1 versus 134.7 ± 16.1 mg/dL; p < 0.001), LDL-c (103.3 ± 13 versus 64.6 ± 12.2 mg/dL; p < 0.001), and postprandial GLP-2 (972.7 ± 326.2 versus 1993.2 ± 1024.7; p = 0. 044). None of the scores obtained in the VAS significantly changed after surgery. After surgery, there were significant correlations of VAS scores and GLP-1 levels in question 01 ("how hungry do you feel?"; R = -0.928; p = .008) and GLP-2 levels in questions 02 ("how full do you feel?" R = 0.943; p = 0.005) and 04 ("how much do you think you can eat now? R = -0.829; p = 0.042).

CONCLUSIONS

Modified BPD does not lead to significant changes in satiety evaluated by the VAS; different aspects of satiety regulation are correlated with the postprandial levels of GLP-1 (hunger feeling) and GLP-2 (satiation feeling and desire to eat) 1 year after modified BPD, signaling a specific postoperative gut hormone-related modulation of appetite.

Biliopancreatic Diversion Decreases Postprandial Apolipoprotein A-IV Levels in Mildly Obese Individuals with Type 2 Diabetes Mellitus: a Prospective Study

BACKGROUND

Bariatric surgery usually leads to improvement on the general lipid profile, but its role in the levels of apolipoprotein A-IV (Apo-AIV) is not completely understood. Apo-AIV is a gut-released lipoprotein which is enrolled in satiety regulation and presents anti-inflammatory, anti-atherogenic, and anti-oxidative properties. The objective of this study was to determine the influence of biliopancreatic diversion (BPD) in the levels of Apo-AIV.

METHODS

This is a prospective exploratory study which evaluated eight obese individuals with type 2 diabetes mellitus (T2DM) who underwent BPD (Scopinaro operation) and were followed-up for 12 months. Apo-AIV levels were determined by means of serial dosages through a standard meal tolerance test (MTT) in the immediate preoperative period and then 12 months later.

RESULTS

There was a significant change in the Apo-AIV curve following MTT before and after surgery. At 0 and 45 min, the Apo-AIV levels did not significantly differ before and after surgery; at 120 and 180 min, Apo-AIV levels were significantly lower following BPD.

CONCLUSIONS

We observed a decrease of postprandial levels of Apo-AIV following MTT in mildly obese individuals with T2DM. This finding appears to be related to the suppression in the Apo-AIV response that obese individuals tend to present. Weight reduction itself, endotoxemia, and the large segments of bypassed intestine may be enrolled in this impaired response.

Energy homeostasis in apolipoprotein AIV and cholecystokinin-deficient mice

Apolipoprotein AIV (ApoAIV) and cholecystokinin (CCK) are well-known satiating signals that are stimulated by fat consumption. Peripheral ApoAIV and CCK interact to prolong satiating signals. In the present study, we hypothesized that ApoAIV and CCK control energy homeostasis in response to high-fat diet feeding. To test this hypothesis, energy homeostasis in ApoAIV and CCK double knockout (ApoAIV/CCK-KO), ApoAIV knockout (ApoAIV-KO), and CCK knockout (CCK-KO) mice were monitored. When animals were maintained on a low-fat diet, ApoAIV/CCK-KO, ApoAIV-KO, and CCK-KO mice had comparable energy intake and expenditure, body weight, fat mass, fat absorption, and plasma parameters relative to the controls. In contrast, these KO mice exhibited impaired lipid transport to epididymal fat pads in response to intraduodenal infusion of dietary lipids. Furthermore, ApoAIV-KO mice had upregulated levels of CCK receptor 2 (CCK2R) in the small intestine while ApoAIV/CCK-KO mice had upregulated levels of CCK2R in the brown adipose tissue. After 20 wk of a high-fat diet, ApoAIV-KO and CCK-KO mice had comparable body weight and fat mass, as well as lower energy expenditure at some time points. However, ApoAIV/CCK-KO mice exhibited reduced body weight and adiposity relative to wild-type mice, despite having normal food intake. Furthermore, ApoAIV/CCK-KO mice displayed normal fat absorption and locomotor activity, as well as enhanced energy expenditure. These observations suggest that mice lacking ApoAIV and CCK have reduced body weight and adiposity, possibly due to impaired lipid transport and elevated energy expenditure.

Circulating Apolipoprotein A-IV presurgical levels are associated with improvement in insulin sensitivity after Roux-en-Y gastric bypass surgery

BACKGROUND

Apolipoprotein A-IV (ApoA-IV) has been shown to be involved in obesity and diabetes pathogenesis in animal studies, but its role in humans is uncertain.

OBJECTIVES

The objective of this study was to determine the relation of ApoA-IV with changes in glucose metabolism and weight after bariatric surgery.

SETTING

University Hospital.

METHODS

The patients (n = 49) included lean controls (n = 8) and patients before and after a mean of 7 months after laparoscopic adjustable gastric banding (LAGB, n = 12), laparoscopic Roux-en-Y gastric bypass (RYGB, n = 22), or laparoscopic sleeve gastrectomy (SG, n = 11). ApoA-IV and other hormone assays were performed in the fasting and the postprandial state. Pearson's correlation analyses controlled for baseline BMI and percent excess weight loss (EWL) were used to determine relationships between ApoA-IV levels and insulin resistance (HOMA-IR).

RESULTS

With all bariatric procedures combined, the change in ApoA-IV [533 versus 518 microg/L, P = .813] or ApoA-IV area under the curve (AUC - 1072 versus 1042, P = .939) was not significant. None of the surgeries individually affected levels of fasting or ApoA-IV AUC. Bariatric surgery resulted in a decrease in HOMA-IR (5.3 versus 2.0, P<.001). In the RYGB group, higher baseline ApoA-IV levels correlated with decrease in HOMA-IR [r = -.6, P = .008]. This relationship was independent of EWL and was not observed in the LAGB or SG group. There was no association of ApoA-IV levels with EWL, insulin secretion, Peptide-YY, or leptin levels.

CONCLUSION

Preoperative ApoA-IV levels, rather than changes in levels, positively correlate with improvements in insulin sensitivity independent of weight loss after RYGB.

Hepatic and visceral adipose tissue 11βHSD1 expressions are markers of body weight loss after bariatric surgery

OBJECTIVE

Cortisolemia and 11βHSD1 in liver and adipose tissue are altered in obesity. However, their participation in the development of obesity remains unclear. This study analyzed these parameters in the transition from morbid to type 1 obesity after bariatric surgery.

METHODS

A group of 34 patients with morbid obesity and 22 nonobese subjects were recruited. Initial hypothalamus-pituitary-adrenal (HPA) basal activity and 11βHSD1 mRNA expression in liver, subcutaneous (SAT), and visceral adipose tissue (VAT) were evaluated. A year after bariatric surgery (weight loss of 48 kg), these parameters were reappraised in plasma, SAT, and liver.

RESULTS

Body weight loss was accompanied by a downshift in basal HPA activity and 11βHSD1 expression in SAT. In patients with morbid obesity, 11βHSD1 expression correlated positively with BMI in VAT and negatively in liver at 6 and 12 months after surgery. In SAT, a correlation was observed with body weight only when patients showed type 1 obesity. Insulin, glucose, and HOMA correlated positively with all the HPA indicators and 11βHSD1 expression in SAT.

CONCLUSIONS

Body weight loss after bariatric surgery is accompanied by a downshift in basal HPA activity. Hepatic and VAT 11βHSD1 expressions in morbid obesity are predictors of body weight loss.

Vertical sleeve gastrectomy restores glucose homeostasis in apolipoprotein A-IV KO mice

Bariatric surgery is the most successful strategy for treating obesity, yet the mechanisms for this success are not clearly understood. Clinical literature suggests that plasma levels of apolipoprotein A-IV (apoA-IV) rise with Roux-en-Y gastric bypass (RYGB). apoA-IV is secreted from the intestine postprandially and has demonstrated benefits for both glucose and lipid homeostasis. Because of the parallels in the metabolic improvements seen with surgery and the rise in apoA-IV levels, we hypothesized that apoA-IV was necessary for obtaining the metabolic benefits of bariatric surgery. To test this hypothesis, we performed vertical sleeve gastrectomy (VSG), a surgery with clinical efficacy very similar to that for RYGB, in whole-body apoA-IV knockout (KO) mice. We found that VSG reduced body mass and improved both glucose and lipid homeostasis similarly in wild-type mice compared with apoA-IV KO mice. In fact, VSG normalized the impairment in glucose tolerance and caused a significantly greater improvement in hepatic triglyceride storage in the apoA-IV KO mice. Last, independent of surgery, apoA-IV KO mice had a significantly reduced preference for a high-fat diet. Altogether, these data suggest that apoA-IV is not necessary for the metabolic improvements shown with VSG, but also suggest an interesting role for apoA-IV in regulating macronutrient preference and hepatic triglyceride levels. Future studies are necessary to determine whether this is the case for RYGB as well.

Baseline circulating ghrelin does not predict weight regain neither maintenance of weight loss after gastric bypass at long term

BACKGROUND

Predictors of weight loss (WL) or weight regain (WR) after Roux-en-Y gastric bypass (RYGBP) are not established. The aim of this study was to analyze the usefulness of some baseline peptides (leptin, insulin, and ghrelin) as biomarkers of WL and WR in morbid obese patients after RYGBP at long term.

METHODS

Seventy-six morbid obese (47 women, age 41.6 ± 9.6 years, body mass index [BMI] 52.1 ± 8 kg/m(2)) patients were evaluated at baseline and at 1, 2, and 6 years after surgery.

RESULTS

Excess body weight loss after 6 years was of 63.9%. Age, BMI, and studied hormones at baseline or their changes over time did not predict long-term excess body weight loss. WR greater than 10% was observed in 36.8% of patients between 2 and 6 years of follow-up, but it was not correlated with BMI, age, or baseline peptide concentrations.

CONCLUSION

Measurement of ghrelin, insulin, and leptin before surgery is not useful as predictors of WL or WR at long term after RYGBP.

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.

Ghrelin and eating disorders

There is growing evidence supporting a multifactorial etiology that includes genetic, neurochemical, and physiological components for eating disorders above and beyond the more conventional theories based on psychological and sociocultural factors. Ghrelin is one of the key gut signals associated with appetite, and the only known circulating hormone that triggers a positive energy balance by stimulating food intake. This review summarizes recent findings and several conflicting reports on ghrelin in eating disorders. Understanding these findings and inconsistencies may help in developing new methods to prevent and treat patients with these disorders.

Evolution of lipid profiles after bariatric surgery

BACKGROUND

The most commonly encountered dyslipidemia in obese individuals is characterized by a cluster of interrelated plasma lipid and lipoprotein abnormalities including hypertriglyceridemia, low HDL cholesterol values, and increased small, dense LDL cholesterol particles. The aim of this study was to assess the changes in lipid profiles at baseline (pre-operatively) and at follow-up (6, 12, and 18 months) after a laparoscopic Roux-en-Y gastric bypass (LRYGBP). A retrospective observational study was performed involving all patients who consecutively underwent a LRYGBP between January 1, 2007 and December 31, 2009. Fasting lipids sub-fractions (total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides) were measured and HOMA-IR calculated pre-operatively and at follow-up post-LRYGBP. Pearson's correlation coefficients were used to assess the relationship between excess weight loss (EWL) and lipid sub-fractions. ANOVA was used to assess the differences between each lipid sub-fraction at various time-points.

METHODS

One hundred twenty eight (N = 128) medical charts were reviewed, and those containing data on lipid fractions at the three follow-up time-points were analyzed. One hundred fourteen patients (N = 114), 84 of whom were women (73.7%), were finally included in the study.

RESULTS

Total cholesterol, LDL cholesterol, triglycerides, and HOMA-IR were significantly reduced after LRYGBP (P < 0.0005 for all). Inversely, HDL cholesterol disclosed a significant rise (P < 0.0005). Noteworthy significant associations between lipid subfractions and EWL were detected overall (P < 0.0005 for all). A gender effect was found since female patients displayed a milder association than male patients (P < 0.0005).

CONCLUSIONS

LRYGBP-induced weight loss improves the lipid profile while reducing insulin resistance, with male patients showing a better profile than female patients.

Mechanisms responsible for excess weight loss after bariatric surgery

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

Problems in identifying predictors and correlates of weight loss and maintenance: implications for weight control therapies based on behaviour change

Weight management is a dynamic process, with a pre-treatment phase, a treatment (including process) phase and post-treatment maintenance, and where relapse is possible during both the treatment and maintenance. Variability in the statistical power of the studies concerned, heterogeneity in the definitions, the complexity of obesity and treatment success, the constructs and measures used to predict weight loss and maintenance, and an appreciation of who and how many people achieve it, make prediction difficult. In models of weight loss or maintenance: (i) predictors explain up to 20-30% of the variance; (ii) many predictors are the sum of several small constituent variables, each accounting for a smaller proportion of the variance; (iii) correlational or predictive relationships differ across study populations; (iv) inter-individual variability in predictors and correlates of outcomes is high and (v) most of the variance remains unexplained. Greater standardization of predictive constructs and outcome measures, in more clearly defined study populations, tracked longitudinally, is needed to better predict who sustains weight loss. Treatments need to develop a more individualized approach that is sensitive to patients' needs and individual differences, which requires measuring and predicting patterns of intra-individual behaviour variations associated weight loss and its maintenance. This information will help people shape behaviour change solutions to their own lifestyle needs.

Changes in neurohormonal gut peptides following bariatric surgery

The rising prevalence of obesity has reached pandemic proportions, with an associated cost estimated at up to 7% of health expenditures worldwide. Bariatric surgery is currently the only effective long-term treatment for obesity and obesity-related co-morbidities in clinically severely obese patients. However, the precise physiological mechanisms underlying the postsurgical reductions in caloric intake and body weight are poorly comprehended. It has been suggested that changes in hormones involved in hunger, food intake and satiety via the neurohormonal network may contribute to the efficacy of bariatric procedures. In this review, we consider how gastrointestinal hormone concentrations, involved in appetite and body weight regulation via the gut-brain axis, are altered by different bariatric procedures. Special emphasis is placed on neurohormonal changes following Roux-en-Y gastric bypass surgery, which is the most common and effective procedure used today.

The neurohormonal regulation of energy intake in relation to bariatric surgery for obesity

Obesity has reached pandemic proportions, with bariatric surgery representing the only currently available treatment demonstrating long-term effectiveness. Over 200,000 bariatric procedures are performed each year in the US alone. Given the reliable and singular success of bariatric procedures, increased attention is being paid to identifying the accompanying neurohormonal changes that may contribute to the resulting decrease in energy intake. Numerous investigations of postsurgical changes in gut peptides have been conducted, suggesting greater alterations in endocrine function in combination restrictive and malabsorptive procedures (e.g., Roux-en-Y gastric bypass) as compared to purely restrictive procedures (e.g., gastric banding), which may contribute to the increased effectiveness of combination procedures. However, very few studies have been performed and relatively little is known about changes in neural activation that may result from bariatric procedures, which likely interact with changes in gut peptides to influence postsurgical caloric intake. This review provides a background in the neurohormonal regulation of energy intake and discusses how differing forms of bariatric surgery may affect the neurohormonal network, with emphasis on Roux-en-Y gastric bypass, the most commonly performed procedure worldwide. The paper represents an invited review by a symposium, award winner or keynote speaker at the Society for the Study of Ingestive Behavior [SSIB] Annual Meeting in Portland, July 2009.

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

OBJECTIVE

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

RESEARCH METHODS AND PROCEDURE

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

RESULTS

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

CONCLUSIONS

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

Endocrine and metabolic response to gastric bypass

PURPOSE OF REVIEW

Diabetes resolves in 80% of individuals undergoing successful Roux-en-Y gastric bypass. Absolute caloric restriction alone resulting from gastric anatomic changes indeed leads to weight loss; however, immediate effects in glycemic control often precede substantial weight loss typically associated with insulin sensitivity. One putative explanation relates to hormonal effects accompanying Roux-en-Y gastric bypass. We reviewed the existing and recent literature to investigate the hormonal changes accompanying Roux-en-Y gastric bypass.

RECENT FINDINGS

Changes in levels of five candidate enteric hormones have been recently associated with early postoperative glycemic control following Roux-en-Y gastric bypass; the strongest effects are seen with variations in glucagon-like peptide-1, glucose-dependent insulinotropic peptide and ghrelin.

SUMMARY

The unique hybridization of static anatomic restriction and dynamic absorptive bypass lends a duality to the beneficial effects of Roux-en-Y gastric bypass. This duality likely explains the short-term and long-term resolution of diabetes in patients undergoing Roux-en-Y gastric bypass.

Metabolic surgery and gut hormones - a review of bariatric entero-humoral modulation

The global pandemic of obesity is increasing. Inappropriate food intake relative to energy expenditure results in increased adiposity. These factors are partly regulated by signals through the gut-brain and adipose-brain axes. Metabolic operations (otherwise known as Bariatric surgery) offer the most effective results for sustained metabolic improvement and weight loss. They modulate a number of gut hormones that constitute the gut-brain axis. This review summarizes the literature to-date reporting the gut hormone changes associated with these operations and their subsequent effects on appetite. Understanding the anatomical differences between each operation and how these can differentially regulate gut hormonal release can provide new treatments and targets for obesity, appetite and metabolic disorders.