Gastric balloon to treat obesity: a double-blind study in nondieting subjects

Ultraprocessed Foods and Obesity Risk: A Critical Review of Reported Mechanisms

Epidemiologic evidence supports a positive association between ultraprocessed food (UPF) consumption and body mass index. This has led to recommendations to avoid UPFs despite very limited evidence establishing causality. Many mechanisms have been proposed, and this review critically aimed to evaluate selected possibilities for specificity, clarity, and consistency related to food choice (i.e., low cost, shelf-life, food packaging, hyperpalatability, and stimulation of hunger/suppression of fullness); food composition (i.e., macronutrients, food texture, added sugar, fat and salt, energy density, low-calorie sweeteners, and additives); and digestive processes (i.e., oral processing/eating rate, gastric emptying time, gastrointestinal transit time, and microbiome). For some purported mechanisms (e.g., fiber content, texture, gastric emptying, and intestinal transit time), data directly contrasting the effects of UPF and non-UPF intake on the indices of appetite, food intake, and adiposity are available and do not support a unique contribution of UPFs. In other instances, data are not available (e.g., microbiome and food additives) or are insufficient (e.g., packaging, food cost, shelf-life, macronutrient intake, and appetite stimulation) to judge the benefits versus the risks of UPF avoidance. There are yet other evoked mechanisms in which the preponderance of evidence indicates ingredients in UPFs actually moderate body weight (e.g., low-calorie sweetener use for weight management; beverage consumption as it dilutes energy density; and higher fat content because it reduces glycemic responses). Because avoidance of UPFs holds potential adverse effects (e.g., reduced diet quality, increased risk of food poisoning, and food wastage), it is imprudent to make recommendations regarding their role in diets before causality and plausible mechanisms have been verified.

Neural signalling of gut mechanosensation in ingestive and digestive processes

Eating and drinking generate sequential mechanosensory signals along the digestive tract. These signals are communicated to the brain for the timely initiation and regulation of diverse ingestive and digestive processes - ranging from appetite control and tactile perception to gut motility, digestive fluid secretion and defecation - that are vital for the proper intake, breakdown and absorption of nutrients and water. Gut mechanosensation has been investigated for over a century as a common pillar of energy, fluid and gastrointestinal homeostasis, and recent discoveries of specific mechanoreceptors, contributing ion channels and the well-defined circuits underlying gut mechanosensation signalling and function have further expanded our understanding of ingestive and digestive processes at the molecular and cellular levels. In this Review, we discuss our current understanding of the generation of mechanosensory signals from the digestive periphery, the neural afferent pathways that relay these signals to the brain and the neural circuit mechanisms that control ingestive and digestive processes, focusing on the four major digestive tract parts: the oral and pharyngeal cavities, oesophagus, stomach and intestines. We also discuss the clinical implications of gut mechanosensation in ingestive and digestive disorders.

Placebo comparator group selection and use in surgical trials: the ASPIRE project including expert workshop

BACKGROUND

The use of placebo comparisons for randomised trials assessing the efficacy of surgical interventions is increasingly being considered. However, a placebo control is a complex type of comparison group in the surgical setting and, although powerful, presents many challenges.

OBJECTIVES

To provide a summary of knowledge on placebo controls in surgical trials and to summarise any recommendations for designers, evaluators and funders of placebo-controlled surgical trials.

DESIGN

To carry out a state-of-the-art workshop and produce a corresponding report involving key stakeholders throughout.

SETTING

A workshop to discuss and summarise the existing knowledge and to develop the new guidelines.

RESULTS

To assess what a placebo control entails and to assess the understanding of this tool in the context of surgery is considered, along with when placebo controls in surgery are acceptable (and when they are desirable). We have considered ethics arguments and regulatory requirements, how a placebo control should be designed, how to identify and mitigate risk for participants in these trials, and how such trials should be carried out and interpreted. The use of placebo controls is justified in randomised controlled trials of surgical interventions provided that there is a strong scientific and ethics rationale. Surgical placebos might be most appropriate when there is poor evidence for the efficacy of the procedure and a justified concern that results of a trial would be associated with a high risk of bias, particularly because of the placebo effect.

CONCLUSIONS

The use of placebo controls is justified in randomised controlled trials of surgical interventions provided that there is a strong scientific and ethics rationale. Feasibility work is recommended to optimise the design and implementation of randomised controlled trials. An outline for best practice was produced in the form of the Applying Surgical Placebo in Randomised Evaluations (ASPIRE) guidelines for those considering the use of a placebo control in a surgical randomised controlled trial.

LIMITATIONS

Although the workshop participants involved international members, the majority of participants were from the UK. Therefore, although every attempt was made to make the recommendations applicable to all health systems, the guidelines may, unconsciously, be particularly applicable to clinical practice in the UK NHS.

FUTURE WORK

Future work should evaluate the use of the ASPIRE guidelines in making decisions about the use of a placebo-controlled surgical trial. In addition, further work is required on the appropriate nomenclature to adopt in this space.

FUNDING

Funded by the Medical Research Council UK and the National Institute for Health Research as part of the Medical Research Council-National Institute for Health Research Methodology Research programme.

Impact of Adjunctive Pharmacotherapy With Intragastric Balloons for the Treatment of Obesity

BACKGROUND

We conducted this study to compare the weight loss outcome of intragastric balloons (IGBs) in conjunction with pharmacotherapy vs IGB and intensive lifestyle changes alone.

METHODS

This was a multicenter, non-randomized, retrospective study involving 4 academic hospitals. Patients underwent IGB placement with or without concomitant anti-obesity pharmacotherapy. The primary outcome was percent total weight loss (TBWL) after IGB placement at 6 and 12 months.

RESULTS

This study included 102 patients, with 23 patients (mean age 46.6 years, 82.6% female) treated with IGB/pharmacotherapy and 79 patients (mean age 46.0 years, 88.6% female) treated with IGB/lifestyle modifications. Patients had a 100% follow-up rate at 6 and 12 months. At 6 months following IGB placement, both groups achieved a similar %TBWL. At 12 months, %TBWL was greater in the IGB/pharmacotherapy group (12.6% ± 1.2 vs 9.7% ± 0.7, P = .04). 65.2% of patients achieved ≥10% TBWL at 12 months in the IGB/pharmacotherapy group, compared to 38.0% in the IGB/lifestyle group (P < .05). The proportion of patients that achieved ≥15% weight loss at 12 months was also significantly different between the IGB/pharmacotherapy and IGB/lifestyle groups (30.4% vs 20.3%, P < .05).

DISCUSSION

IGB with concomitant use of pharmacotherapy did not improve weight loss while the IGB was in place compared to IGB and lifestyle changes. However, patients receiving IGB with pharmacotherapy did have greater weight loss and diminished weight regain after balloon removal compared to those receiving just IGB and lifestyle changes.

Bariatric and metabolic endoscopy: impact on obesity and related comorbidities

The global obesity pandemic is among the most significant public health crises today. Furthermore, obesity remains a major risk factor for many weight-related comorbid conditions including cardiovascular disease, type 2 diabetes mellitus, liver disease, and cancer. Endoscopic bariatric therapies are currently on the rise as a new tool in the fight against the obesity epidemic, offering patients an alternative to more invasive surgery and a more effective option than diet and lifestyle modifications. The aim of this review article is to summarize the current literature regarding endoscopic bariatric therapies and their impact on obesity and its associated metabolic complications.

Vagally Mediated Gut-Brain Relationships in Appetite Control-Insights from Porcine Studies

Signals arising from the upper part of the gut are essential for the regulation of food intake, particularly satiation. This information is supplied to the brain partly by vagal nervous afferents. The porcine model, because of its sizeable gyrencephalic brain, omnivorous regimen, and comparative anatomy of the proximal part of the gut to that of humans, has provided several important insights relating to the relevance of vagally mediated gut-brain relationships to the regulation of food intake. Furthermore, its large size combined with the capacity to become obese while overeating a western diet makes it a pivotal addition to existing murine models, especially for translational studies relating to obesity. How gastric, proximal intestinal, and portal information relating to meal arrival and transit are encoded by vagal afferents and their further processing by primary and secondary brain projections are reviewed. Their peripheral and central plasticities in the context of obesity are emphasized. We also present recent insights derived from chronic stimulation of the abdominal vagi with specific reference to the modulation of mesolimbic structures and their role in the restoration of insulin sensitivity in the obese miniature pig model.

Intragastric Balloon Treatment for Obesity: Review of Recent Studies

INTRODUCTION

The FDA recently approved three intragastric balloon (IGB) devices, ReShape, ORBERA™, and Obalon for treatment of obesity. Given the high cost, complication risk, and invasiveness of bariatric surgery, IGB treatment may present a safer and lower cost option for weight reduction. IGBs are generally placed in the stomach endoscopically for up to 6 months to reduce gastric capacity, enhance feelings of fullness, and induce weight loss. The mechanism of action likely involves stimulation of gastric mechanoreceptors triggering short-acting vagal signals to brain regions implicated in satiety. Balloon efficacy may be influenced by balloon volume, patient gastric capacity, and treatment duration.

METHODS

This review focused on eight recent (2006-present) randomized controlled trials (RCTs) comparing percentage total body weight loss (%TBWL) between IGB and control groups including three reviewed by the FDA. %TBWL based on the reviewed studies was also compared with bariatric surgery and pharmacotherapy.

RESULTS

Of the eight IGB studies, five had balloon treatment duration of 6 months. Efficacy at 6 months, based on a pooled weighted-mean %TBWL, was 9.7%, and the control-subtracted %TBWL was 5.6%. When one study without SDs was removed, the weighted mean %TBWL was 9.3 ± 5.7% SD, and control-subtracted %TBWL was 5.5 ± 7.8%, which was statistically greater than controls. IGB showed lower efficacy than bariatric surgery (median weight loss of 27% for Rouen-Y gastric bypass (RYGB). The control-subtracted %TBWL over 6 months of 5.5-5.6% is less than the most efficacious FDA-approved weight loss drug, Qsymia. At the recommended dose, Qsymia has a placebo-subtracted %TBWL at 6 months of approximately 6.6%. The weighted mean reported incidence of serious adverse events (SAEs) in the IGB group across all eight studies was 10.5%. Only six of the eight reviewed studies reported adverse events (AEs) in the IGB group, with a pooled reported incidence of 28.2%. Recently, the FDA reported new AEs including acute pancreatitis with ReShape and ORBERA™.

CONCLUSION

Based on the available evidence, it is unlikely that IGB use will supplant other forms of obesity treatment. The estimated cost of endoscopic balloon implantation and retrieval is US $8,150. Collectively, a relatively small control-subtracted %TBWL and the potential for serious complications makes IGB unlikely to become widely adopted. Given the recent FDA warning, IGB longevity on the market is questionable.

Critical review of sham surgery clinical trials: Confounding factors analysis

OBJECTIVE

Sham surgery (placebo surgery) is an intervention that omits the step thought to be therapeutically necessary. In surgical clinical trials, sham surgery serves an analogous purpose to placebo drugs, neutralizing biases such as the placebo effect. A critical review was performed to study the statistical relevance of the clinical trials about sham surgery in the light of potential confounding factors.

MATERIALS AND METHODS

For the critical review 52 articles were included. The possible confounding factors have been studied using a structured interpretative research form designed by the authors. This form includes the following ten confounding factors: I), lack of homogeneity among inclusion/exclusion criteria. II), false double blind. III), lack of post-surgery double blind. IV), power of the study. V), sample characteristics. VI), lost patients to Follow-up. VII), gender distribution. VIII), age equilibrium. IX), lack of psychological patient evaluation. X), lack of psychiatric patient evaluation. In most of the studies, at least one confounding factor was present.

RESULTS

The analysis of the confounding factors showed that they could influence the reliability of the surgical placebo effects.

CONCLUSIONS

The validity of sham surgery should be reconsidered.

Effectiveness of intragastric balloon for obesity: A systematic review and meta-analysis based on randomized control trials

BACKGROUND

Obesity has become a worldwide epidemic, and many methods are currently used to reduce obesity. This systematic review shows the effectiveness of the intragastric balloon (IGB) method compared to the sham/diet (s/d) method.

OBJECTIVE

To demonstrate the effectiveness of the IGB method compared to the s/d method.

SETTING

Hospital das Clinicas da Universidade de São Paulo, Brazil, Public Hospital.

METHODS

After searching MEDLINE, Embase, Cochrane, Lilacs, Scopus, and CINAHL, only enrolled randomized control trials comparing IGB/diet with s/d were analyzed. For qualitative analysis, 12 studies were selected, and 9 of these were acceptable for quantitative analysis.

RESULTS

The IGB/diet is more effective than s/d when comparing body mass index (BMI) loss with a mean difference of 1.1 kg/m(2) by the Student's t test and 1.41 kg/m(2) by the meta-analysis, with significant differences in both. It is also more effective in weight loss (WL), with a mean difference of 2 kg by the Student's t test and 3.55 kg by the meta-analysis. In the qualitative analysis of % excess WL (%EWL), the mean %EWL is 14.0% in favor of the IGB group compared to the s/d group by the Student's t test; however, no significant difference was found between these groups by quantitative analysis.

CONCLUSION

Based on randomized control trial data alone, IGB>400 mL is more effective than sham/diet in achieving BMI loss, WL, and %EWL.

Neuroimaging of gastric distension and gastric bypass surgery

Several neuroimaging studies are presented, which derive from prior work on gastric distension. Using a nonsurgical approach, we inserted gastric balloons into rats, which led to a marked decrease in food intake that normalized at 8 weeks. Body weight, however, remained below controls, which encouraged pursuit of studies in humans. A gastric balloon was inserted in obese and lean subjects, and filled through a tube that led behind the subject with water to 0, 200, 400, 600, 800 mL, on different days prior to ingestion of a liquid meal. As gastric volume increased, intake decreased by about 40%. Stomach capacity was then investigated using a gastric balloon, by assessing subjective (maximal tolerance) and objective measures (gastric compliance). Obese individuals had a much larger stomach capacity than lean by both measures. Next, in a 2-month study, an indwelling gastric balloon was inflated to 400 mL for 1 month and deflated for 1 month in counterbalanced order. Body weight was reduced during the month when the balloon was inflated within the 2nd and 3rd week. The subsequent study involved fMRI in response to gastric distension of 0, 250, and 500 mL while the subject was in a scanner. Ratings of fullness, but not discomfort, increased at 500 mL. Amygdala and insula activation were associated with gastric distension. The amygdala, as part of the limbic system, is involved in emotion and reward, and the insula in interoception. The right amygdala activation was inversely related to BMI, consistent with greater gastric capacity at a higher BMI. The next fMRI study in obese and lean subjects used visual and auditory stimuli of high energy dense (ED) and low ED foods. Increased activation was observed in the midbrain, putamen, posterior cingulate gyrus, hippocampus, and superior temporal gyrus in the obese vs. lean group in response to high vs. low ED food cues. Several of these areas lie within the mesolimbic reward pathway, and greater activation to high ED foods in the obese, suggests they have increased reward-driven eating behavior. Lastly, an fMRI study using the same stimuli was conducted pre and post-gastric bypass surgery. There were postsurgical reductions in neural activity in mesolimbic areas including the prefrontal cortex, and to a greater degree for high ED than low ED cues, reflecting more normalized responses. Through the use of various methodologies, the stomach's influence on food intake, sensations of fullness, and brain activation is presented with suggestions for future research.

Fasting and meal-induced CCK and PP secretion following intragastric balloon treatment for obesity

BACKGROUND

Satiety is centrally and peripherally mediated by gastrointestinal peptides and the vagal nerve. We aimed to investigate whether intragastric balloon treatment affects satiety through effects on fasting and meal-stimulated cholecystokinin (CCK) and pancreatic polypeptide (PP) secretion.

METHODS

Patients referred for obesity treatment were randomised to 13 weeks of sham treatment followed by 13 weeks of balloon treatment (group 1; sham/balloon) or to twice a 13-week period of balloon treatment (group 2; balloon/balloon). Blood samples were taken for fasting and meal-stimulated CCK and PP levels at the start (T0) and after 13 (T1) and 26 (T2) weeks. Patients filled out visual analogue scales (VAS) to assess satiety.

RESULTS

Forty-two patients (35 females, body weight 125.1 kg, BMI 43.3 kg/m(2)) participated. In group 1, basal CCK levels decreased but meal-stimulated response remained unchanged after 13 weeks of sham treatment. In group 2, basal and meal-stimulated CCK levels decreased after 13 weeks of balloon treatment. At the end of the second 13-week period, when group 1 had their first balloon treatment, they duplicated the initial 13-week results of group 2, whereas group 2 continued their balloon treatment and reduced meal-stimulated CCK release. Both groups showed reduced meal-stimulated PP secretions at T1 and T2 compared to T0. Changes in diet composition and VAS scores were similar. Improvements in glucose homeostasis partly explained the PP results.

CONCLUSIONS

The reduced CCK and PP secretion after balloon positioning was unexpected and may reflect delayed gastric emptying induced by the balloon. Improved glucose metabolism partly explained the reduced PP secretion. Satiety and weight loss were not adversely influenced by these hormonal changes.

Endoscopic treatment of obesity

BACKGROUND

The increasing incidence of obesity and overweight among children and adolescents will be reflected by the imminent increase in the number of obese patients who require more definitive methods of treatment. There is great interest in new, safe, simple, nonsurgical procedures for weight loss.

OBJECTIVE

To provide an overview of new endoscopic methods for the treatment of obesity.

METHODS

An English-language literature search on endoscopic interventions, endoscopically placed devices and patient safety was performed in the MEDLINE and Cochrane Library databases.

RESULTS

The literature search yielded the following weight loss methods: space-occupying devices (widely used), gastric capacity reduction, modifying gastric motor function and malabsorptive procedures. A commercially available intragastric balloon was the most commonly used device for weight loss. In specific subgroups of patients, it improved quality of life, decreased comorbidities and served as a bridge to surgery. More evidence regarding the potential benefits and safety of other commercially available intragastric balloons is needed to clarify whether they are superior to the most commonly used one. Moreover, early experiences with transoral gastroplasty, the duodenal-jejunal bypass sleeve and an adjustable, totally implantable intragastric prosthesis, indicate that they may be viable options for obesity treatment. Other agents, such as botulinum toxin and a device known as the 'butterfly', are currently at the experimental stage.

CONCLUSION

New endoscopic methods for weight loss may be valuable in the treatment of obesity; however, more clinical experience and technical improvements are necessary before implementing their widespread use.

Intragastric balloon treatment for obesity: what does it really offer?

Obesity is a chronic metabolic disorder with considerable health risks, which can be approved by a sustained modest weight loss. This can be achieved by medical treatment through behavioral therapy, diet, exercise and pharmacotherapy. Surgery is often needed for the severely obese. Intragastric balloon treatment stands in between, being more drastic than medical treatment but less invasive than surgery. In the light of the high premature deflation rate and the high incidence of gastric ulcers, a safer balloon had to be awaited, constructed according to predefined criteria. This new balloon (BioEnterics Intragastric Balloon) promoted a weight loss of 5-9 BMI units in 6 months with an impressive improvement of obesity-associated comorbidities. A weight regain of 25-40% has to be considered in a 1-year balloon-free follow-up period. A failure rate of 15% was observed in studies that defined a successful weight loss. With respect to safety, there was no mortality. Gastrointestinal complications, mainly consisting of esophagitis, were present in 5.5%. Intolerance of the balloon resulted in its removal in 7%. Balloons deflated in 8% with an uneventful outcome in all except 5 patients, who had to be operated. Balloon treatment is a valuable method, but nonresponse, intolerance and weight regain have to be taken into account.

A pilot study to evaluate the safety, tolerance, and efficacy of a novel stationary antral balloon (SAB) for obesity

BACKGROUND

A 150 cm pear-shaped gastric balloon with a 30 cm-long duodenal stem and a 7 g metallic weight at its distal end was designed and developed to facilitate weight loss by (a) delaying gastric emptying thus enhancing interprandial satiety, and (b) stimulating antral and duodenal receptors of satiation.

METHODS

Twenty-six patients (body mass index of 29 to 40 kg/m) who failed to lose weight despite dietary intervention underwent endoscopic implantation of the balloon device. Patients were monitored for tolerance to the balloon, complications, weight loss, and compliance with a restricted caloric intake.

RESULTS

Six men and 20 women with a median body weight of 93.0 kg (range, 73.5 to 119.9), median body mass index 34.3 kg/m (range, 28.8 to 39.5) underwent balloon implantation for a median period of 4.0 months (range, 0.75 to 6.0). Twenty-two patients successfully complied with a 1250 to 1500 kcal daily diet restriction during the study period. Median weight reduction was 6.5 kg (range, 3.7 to 19.9). Patients with initial body weight of >90 kg tended to loose more weight (8.1 kg) than patients weighing <90 kg (4.5 kg) (P=0.14). Nine patients with dwell times of 6 months lost 11.5+/-4.6 kg. The balloon malfunctioned in 4 patients (in 1 patient, the balloon leaked spontaneously but remained in the stomach and in 3 patients, the balloon migrated distally).

CONCLUSIONS

Our novel balloon device may be effective in inducing weight loss by promoting compliance with a restricted caloric intake and is well tolerated due to its small size. Complications resulted from balloon rupture, which can be easily prevented by enhancements in design and use of alternative materials.

Safety of the Ullorex oral intragastric balloon for the treatment of obesity

BACKGROUND

Intragastric balloons have been used for weight loss with varying success. Widespread use of intragastric balloons has been limited because balloons must be placed in, and removed from, the stomach endoscopically. Development of a balloon that does not require endoscopy suggests that obesity treatment with intragastric balloons is feasible. The purpose of this study was to test the Ullorex oral intragastric balloon (OIB) in a sample of human participants.

METHODS

The Ullorex OIB is a large capsule that is injected with citric acid and swallowed. After 4 minutes, the balloon inflates to 300 cm(3). Stomach acid degrades a plug on the balloon over 25-30 days, when the balloon deflates and passes in feces. The Ullorex OIB was tested in 12 humans (two participants received placebo capsules). Body weight was monitored before and after balloon placement, and test meals quantified food intake among 6 of the 12 participants, all of whom received one balloon.

RESULTS

A single significant adverse event occurred. The one participant randomized to receive three balloons developed nausea and vomiting, requiring intravenous fluids, which was likely influenced by noncompliance (eating solid foods after balloon placement). Participants who received balloons had a significant mean weight loss over 2 weeks, amounting to 1.5 kg (p < 0.05). A marginally significant food intake reduction from baseline to week 1 was found (149 kcal, 24.4%) (p = 0.055).

CONCLUSIONS

The Ullorex OIB was successfully utilized in this study, with one serious adverse event that was likely influenced by noncompliance. Body weight and food intake data suggest that the Ullorex OIB be tested further as a possible treatment for obesity.

Intragastric balloon for obesity

BACKGROUND

Obesity is one of the major public health problems of modern society. Intragastric balloon (IGB) treatment for obesity has been developed as a temporary aid. Its primary objective is the treatment of obese people, who have had unsatisfactory results in their clinical treatment for obesity, despite of being cared for by a multidisciplinary team, and super obese patients with a higher surgical risk. However, the effects of different IGB procedures compared with conventional treatments and with each other are uncertain.

OBJECTIVES

To assess the effects of intragastric balloon in people with obesity.

SEARCH STRATEGY

Studies were obtained from computerised searches of MEDLINE, EMBASE, LILACS, The Cochrane Library and other electronic databases. Furthermore, reference lists of relevant articles and hand searches of selected journals were performed. Experts in the field were contacted.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials fulfilling the inclusion criteria were used. Short term weight loss is common, so studies were included if they reported measurements after a minimum of four weeks follow-up.

DATA COLLECTION AND ANALYSIS

Data were extracted by one reviewer and checked independently by two reviewers. Two reviewers independently assessed the quality of trials.

MAIN RESULTS

Nine randomised controlled trials involving 395 patients were included. Six out of nine studies had a follow-up of less than one year, the longest study duration was 24 months. Only a third of the analysed studies revealed a low risk of bias. No information was available on quality of life, all-cause mortality and morbidity. Compared with conventional management, IGB did not show convincing evidence of a greater weight loss. On the other hand, complications of intragastric balloon placement occurred, however few of a serious nature. The relative risks for minor complications like gastric ulcers and erosions were significantly raised.

AUTHORS' CONCLUSIONS

Evidence from this review is limited for decision making, since there was large heterogeneity in IGB trials, regarding both methodological and clinical aspects. However, a co-adjuvant factor described by some authors in the loss and maintenance of weight has been the motivation and the encouragement to changing eating habits following a well-organized diet and a program of behavioural modification. The IGB alone and the technique of positioning appear to be safe. Despite the evidence for little additional benefit of the intragastric balloon in the loss of weight, its cost should be considered against a program of eating and behavioural modification.

Effect of gastric distension prior to eating on food intake and feelings of satiety in humans

The factors that regulate food intake and satiation are complex; it has been suggested that signals arising from the small intestine and the stomach play an important role. It is still unknown, to what extent pure mechanical distension of the gastric fundus and antrum can alter food intake. Our aim was therefore to investigate whether transient gastric fundus and antrum distension applied prior to meal ingestion can trigger satiation in healthy humans. Two sequential, randomized, double-blind, four-period cross-over designed studies were performed in 24 healthy male volunteers: (1) 12 subjects underwent four intragastric balloon distension experiments of the fundus (0, 400, 600, 800 ml) before a standard meal intake; (2) 12 subjects underwent intragastric balloon distension experiments of the antrum under the following conditions: 0 ml balloon distension of the antrum plus intraduodenal (ID) saline or ID fat, and 300 ml antrum distension plus ID saline or ID fat. Shortly after the distension period, subjects were free to eat and drink as much as they wished. Neither gastric fundus nor antrum distension showed a reduction in calorie intake. Distending the fundus affected the mean Visual Analogue Scale (VAS) in the premeal period: subjects experienced a reduced degree of hunger and a concomitant feeling of fullness, but the effect was only apparent during distension with a volume of 600 ml or even 800 ml. Cholecystokinin (CCK) and peptide YY (PYY) were not altered by gastric distension. Transient pure mechanical distension of the fundus or the antrum prior to a meal does not trigger satiation.

Visceral response to acute retrograde gastric electrical stimulation in healthy human

AIM: To investigate the visceral response to acute retrograde gastric electrical stimulation (RGES) in healthy humans and to derive optimal parameters for treatment of patients with obesity.

METHODS: RGES with a series of effective parameters were performed via a bipolar mucosal electrode implanted along the great curvature 5 cm above pylorus of stomach in 12 healthy human subjects. Symptoms associated with dyspepsia and other discomfort were observed and graded during RGES at different settings, including long pulse and pulse train. Gastric myoelectrical activity at baseline and during different settings of stimulation was recorded by a multi-channel electrogastrography.

RESULTS: The gastric slow wave was entrained in all the subjects at the pacing parameter of 9 cpm in frequency, 500 ms in pulse width, and 5 mA in amplitude. The frequently appeared symptoms during stimulation were satiety, bloating, discomfort, pain, sting, and nausea. The total symptom score for each subject significantly increased as the amplitude or pulse width was adjusted to a higher scale in both long pulse and pulse train. There was a wide diversity of visceral responses to RGES among individuals.

CONCLUSION: Acute RGES can result in a series of symptoms associated with dyspepsia, which is beneficial to the treatment of obesity. Optimal parameter should be determined according to the individual sensitivity to electrical stimulation.

Endoscopic treatments for obesity: past, present and future

Obesity is recognized as a serious, chronic illness affecting all ages. The cause for obesity is multi-factorial, which makes successful management complex and challenging. Meaningful weight loss is frequently difficult to achieve, particularly when the goal is not merely to lose weight but to maintain this loss. The efficacy of future endoscopic approaches needs to be validated through well-designed controlled studies, and verification of safety is essential. Endoluminal therapies must have a sound physiologic basis for their development. The availability of specialized radionuclide imaging of gastric capacity and accommodation provide a useful tool in constructing interventions. Endotherapy is likely best suited for nonmorbid obese individuals with BMI ranging from 30 to 39 or as a budge to bariatric surgery. This specific BMI range has been targeted by the National Institutes of Health for emerging technologies. Presurgical weight loss to reduce surgical risk is another potential target group. Regardless of which endoscopic methods prevail, patients will continue to require a comprehensive, multi-modality management approach to this complex disease.

Intragastric balloon for treatment-resistant obesity: safety, tolerance, and efficacy of 1-year balloon treatment followed by a 1-year balloon-free follow-up

BACKGROUND

Prior efforts to treat obesity with intragastric balloons were thwarted by high complication rates. Therefore, fundamental requirements for optimal balloon designs were defined. The aim of the present study was to investigate the effectiveness, the safety, and the tolerance of a new intragastric balloon.

METHODS

Adults with treatment-resistant obesity and no GI contraindications to balloon placement were invited to participate in a randomized, double-blind trial of balloon or sham treatment of 3 months' duration. Patients (sham- and balloon-treated groups) in whom a preset weight-loss goal was achieved were given an additional 9 months of balloon treatment. After removal of the balloon at year 1, patients were followed for a second year without the balloon.

RESULTS

Forty-three treatment-resistant patients (mean body mass index 43.3 kg/m 2) were enrolled. Five patients did not meet the preset weight-loss goal (nonresponse 11.6%). Three patients did not tolerate the balloon (7.0%), with endoscopy demonstrating severe esophagitis. Three other patients developed esophagitis that was related to use of nonsteroidal anti-inflammatory drugs, albeit prohibited (2 patients), or substantial weight loss with balloon treatment (1). In intention-to-treat analysis, sham- and balloon-treated groups had a similar mean weight loss of 11.2 kg (9.0%) and 12.9 kg (10.4%), respectively, during the first 3 months. During months 3 to 6, patients who had sham therapy in months 0 to 3 lost 8.8 kg (7.9%) during the first 3 months of balloon treatment. In contrast, patients in the balloon-treatment group lost 3.9 kg (3.5%) during months 3 to 6 (their second balloon treatment period). The overall weight loss was 20 kg (16.1%) and 16.7 kg (13.4%) after 6 months in the sham/balloon and in the balloon/balloon treated groups (not significant), respectively. After 1-year of balloon treatment, a mean weight loss of 21.3 kg (17.1%) was achieved in all patients, of which 12.6 kg (9.9%) was maintained at the end of the second balloon-free year; 47% of patients sustained a greater than 10% weight loss, with considerably reduced comorbidity. In 33 patients who completed the study per protocol, weight loss was 25.6 kg (20.5%) after 1 year and 14.6 kg (11.4%) after 2 years; 55% maintained a weight loss of greater than 10%. Interventional complications occurred in 1.6% (2/128) and balloon deflations in 2.3% (3/128).

CONCLUSIONS

For patients with treatment-resistant obesity, the intragastric balloon appeared to be safe but was not a treatment option in a fifth of patients. Although an independent benefit of balloon treatment beyond diet, exercise, and behavioral therapy could not be demonstrated in the first 3 months, balloon treatment for 1 year resulted in substantial weight loss, the greater part of which was maintained during the balloon-free second year.

Amylin, food intake, and obesity

Amylin, also known as islet amyloid polypeptide, identified in 1987, is a naturally occurring hormone, released by the beta cells of the pancreas and consists of 37 amino acids. Amylin seems to decrease food intake through both central and peripheral mechanisms and indirectly by slowing gastric emptying. The mean basal amylin concentration is higher in obese than in lean human subjects. The amylin response to oral glucose is also greater in obese subjects, whether or not they have impaired glucose tolerance. The elevated amylin levels in obesity may lead to down-regulation of amylin receptors and lessen the impact of postprandial amylin secretion on satiety and gastric emptying. Amylin administration may overcome resistance at target tissues, delay gastric emptying, and have potential for inducing weight loss in obese individuals.

Unususal increase of lipogenesis in rat white adipose tissue after multiple cycles of starvation-refeeding

The purpose of the study was to determine the response of liver and brown (BAT) and white (WAT) adipose tissue lipogenesis and total body weight in rats subjected to multiple cycles of 3 days of fasting and 3 days of refeeding. Rats fasted for 3 days showed significant reduction in body weight. These changes were reversed on 3 days' refeeding. Body weight was much higher in rats fed ad libitum than in animals experiencing more than one cycle of 3 days of fasting followed by 3 days of refeeding. Despite the significant body weight reduction, an unusual increase of lipogenesis in WAT was found after multiple cycles of starvation-refeeding of rats on standard laboratory diet. The rate of lipogenesis in the liver and BAT was also elevated but to a much smaller extent. A parallel increase in enzymatic activities related to fatty acid synthesis, ie, fatty acid synthase, acetyl-coenzyme A carboxylase, adenosine triphosphate (ATP)-citrate lyase, NADP-linked malic enzyme, and hexose monophosphate shunt dehydrogenases, suggests that the increased rate of lipogenesis in WAT is a consequence of increased lipogenic enzyme activities. These data suggest that upregulation of WAT lipogenesis occurs after the multiple cycles of the starvation-refeeding protocol. An unusual increase of lipogenesis in rat WAT may have a survival advantage, because starved-refed rats must develop the ability to ingest large amounts of food during a refeeding period to store it in a convenient form than can be used as an oxidizable substrate during a period of starvation. Moreover, these results suggest that it is possible to develop appropriate starvation-refeeding conditions that may inhibit body weight gain.

Surgery for obesity

The medical risks of obesity increase exponentially as weight increases, and these risks are reduced by sustained weight loss. Behavior modification and dieting provide an approximately 6% loss of body weight at 1 year. Fenfluramine provides an approximately 8% weight loss at 1 year, which can be doubled to 16% when a drug such as phentermine, which works through a different biochemical mechanism, is added to it. This amount of weight loss is insufficient for many severely obese individuals. It was with these facts in mind that the National Institutes of Health Consensus Conference in 1992 recommended that obesity surgery is an appropriate treatment for patients with a body mass index greater than 40 kg/m2 who had failed in attempts at medical treatment and for patients with a body mass index greater than 35 kg/m2 with severe complications of obesity. Vertically banded gastroplasty and Roux-en-Y gastric bypass are the two operations presently recommended because of their relative safety and effectiveness. This article reviews previous procedures that have provided insight into the mechanisms by which these surgeries cause weight loss. The presently used surgeries and their results also are reviewed because until medical therapy improves substantially, surgery remains the most reasonable treatment option for most morbidly obese patients.

Weight loss induced by gastric implant in rats. Effects of capsaicin sensory denervation

To study the efficacy and mechanism of action of the intragastric bubble, 1- to 5-ml silicone bubbles were surgically implanted into the stomachs of 10- to 12-week-old female rats. To test the hypothesis that the satiety effects of the implant are mediated by visceral sensory nerves, a subgroup was treated as neonates with the sensory neurotoxin capsaicin, 50 mg/kg subcutaneously. In control animals, the implants caused a transient decrease in body weight, compared to sham-implanted animals, most evident at three days and abolished by 18 days after operation. In contrast, capsaicin-treated animals did not lose weight in response to gastric implantation. Substance P was decreased in the vagus nerves of capsaicin-treated animals, confirming sensory denervation. At autopsy, all gastric implanted rats had enlarged stomachs. We conclude that intact sensory innervation is essential for weight loss in response to the gastric bubble.