Gastric distention by balloon and test-meal intake in obese and lean subjects

Independent effects of volume and energy density manipulation on energy intake and appetite in healthy adults: A randomized, controlled, crossover study

Consuming enough energy to meet high energy demands can be challenging for military personnel wherein logistical constraints limit food availability. Increasing dietary energy density (ED) and/or volume density (VD) of rations may be countermeasures, but whether positive linear associations between ED and energy intake (EI) hold at moderate-to-high ED and VD is unclear. This study examined the effects of covertly increasing the ED and VD of moderate ED (≥1.6 kcal/g) foods on appetite and energy intake. Twenty healthy men completed four 2-day treatments in random order by consuming a standardized diet containing three experimental food items (EXP) engineered using leavening, physical compression and fat manipulation to be isovolumetric but lower (L) or higher (H) in ED and VD creating four treatments: LED/LVD, LED/HVD, HED/LVD, HED/HVD. Consumption of EXP was compulsory during two meals and a snack, but remaining intake was self-selected (SSF). Results failed to show any ED-by-VD interactions. During LVD, EI was lower for EXP (-417 kcal [95%CI: 432, -402], p < 0.01) and TOTAL (SSF + EXP) (-276 kcal [95%CI: 470, -83], p = 0.01) compared to HVD, while SSF EI did not differ (140 kcal [-51, 332], p = 0.15). During LED, EI for EXP (-291 kcal [95%CI: 306, -276], p < 0.01) was lower than HED, while SSF EI was higher than HED (203 kcal 95%CI: [12, 394], p = 0.04) and TOTAL EI did not differ (-88 kcal [-282, 105], p = 0.36). Thus, when a small isovolumetric portion of the diet was manipulated, increasing the VD of moderate ED foods failed to elicit compensatory reductions in ad libitum EI while increasing the ED of moderate ED foods did. Findings may support VD manipulation of moderate ED foods as a strategy to promote increased short-term EI in environments wherein logistical burden may limit food volume.

American Society for Gastrointestinal Endoscopy-European Society of Gastrointestinal Endoscopy guideline on primary endoscopic bariatric and metabolic therapies for adults with obesity

This joint ASGE-ESGE guideline provides an evidence-based summary and recommendations regarding the role of endoscopic bariatric and metabolic therapies (EBMTs) in the management of obesity. The document was developed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework. It evaluates the efficacy and safety of EBMT devices and procedures that currently have CE mark or FDA-clearance/approval, or that had been approved within five years of document development. The guideline suggests the use of EBMTs plus lifestyle modification in patients with a BMI of ≥ 30 kg/m2, or with a BMI of 27.0-29.9 kg/m2 with at least 1 obesity-related comorbidity. Furthermore, it suggests the utilization of intragastric balloons and devices for endoscopic gastric remodeling (EGR) in conjunction with lifestyle modification for this patient population.

American Society for Gastrointestinal Endoscopy-European Society of Gastrointestinal Endoscopy guideline on primary endoscopic bariatric and metabolic therapies for adults with obesity

This joint ASGE-ESGE guideline provides an evidence-based summary and recommendations regarding the role of endoscopic bariatric and metabolic therapies (EBMTs) in the management of obesity. The document was developed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework. It evaluates the efficacy and safety of EBMT devices and procedures that currently have CE mark or FDA-clearance/approval, or that had been approved within five years of document development. The guideline suggests the use of EBMTs plus lifestyle modification in patients with a BMI of ≥30 kg/m2, or with a BMI of 27.0-29.9 kg/m2 with at least 1 obesity-related comorbidity. Furthermore, it suggests the utilization of intragastric balloons and devices for endoscopic gastric remodeling (EGR) in conjunction with lifestyle modification for this patient population.

Intraduodenal nutrient infusion differentially alters intestinal nutrient sensing, appetite, and satiety responses in lean and obese subjects

BACKGROUND

Intestinal nutrient sensing regulates food intake and energy metabolism by acting locally and relaying nutritional status to the brain. It is unclear whether these mechanisms are altered in obese humans.

OBJECTIVES

We aimed to investigate differences in duodenal nutrient sensing in humans with or without obesity and the effects of transiently blocking vagal transmission on nutrient sensing, hunger, and appetite.

METHODS

In a single-blinded, randomized, cross-over design, subjects with or without obesity (n = 14 and n = 11, respectively) were infused intraduodenally with saline or a combination of glucose and oleic acid for 90 min (glucose load: 22.5 g, 1 kcal/min; oleic acid load: 10 g, 1 kcal/min) in the presence or absence of local anesthetic (benzocaine). Blood was sampled at 10-min intervals (120-240 min) and 15-min intervals until termination of the study for measurements of gut hormones, insulin, leptin, and C-peptide. Hunger and satiety sensations were scored using the visual analog scale, and hepatic glucose production and glucose oxidation rates were measured.

RESULTS

Duodenal nutrient infusion in lean subjects led to a 65% drop in acyl ghrelin release and robustly increased cholecystokinin 8 (CCK-8) release (65%; P = 0.023); benzocaine infusion delayed this response (2-factor repeated-measures analysis of variance, P = 0.0065). In contrast, subjects with obesity had significantly blunted response to nutrient infusion, and no further effects were observed with benzocaine. Additionally, significant delays were observed in peptide YY (3-36), pancreatic polypeptide, glucose inhibitory peptide, and glucagon-like peptide 1 (7-36) response. No significant interactions were found between body mass index (BMI) or baseline hormone levels and areas under the curve for hormones except CCK-8 (BMI, P = 0.018; baseline CCK, P = 0.013). Nutrient-induced hunger and satiety sensations were impeded by benzocaine only in the lean cohort. Hunger and satiety sensations in subjects with obesity were not responsive to nutrient entry into the duodenum, and no additional effects were observed by blocking neural signaling.

CONCLUSION

Nutrient-induced gut hormone release and response to transient vagal blockade are significantly blunted in subjects with obesity. This trial was registered at clinicaltrials.org as NCT02537314.

Six intragastric balloons: Which to choose?

Endoscopically placed intragastric balloons (IGBs) have played a significant role in obesity treatment over the last 30 years, successfully bridging the gap between lifestyle modification/pharmacotherapy and bariatric surgery. Since they provide a continuous sensation of satiety that helps the ingestion of smaller portions of food, facilitating maintenance of a low-calorie diet, they have generally been considered an effective and reversible, less invasive, non-surgical procedure for weight loss. However, some studies indicate that balloons have limited sustainable effectiveness for the vast majority attempting such therapy, resulting in a return to the previous weight after balloon removal. In this review we try to summarize the pros and cons of various balloon types, to guide decision making for both the physician and the obese individual looking for effective treatment. We analyzed the six most commonly used IGBs, namely the liquid-filled balloons Orbera, Spatz3, ReShape Duo and Elipse, and the gas-filled Heliosphere and Obalon - also including comments on the adjustable Spatz3, and the swallowable Obalon and Elipse - to optimize the choice for maximum efficacy and safety.

Gastrointestinal Vagal Afferents and Food Intake: Relevance of Circadian Rhythms

Gastrointestinal vagal afferents (VAs) play an important role in food intake regulation, providing the brain with information on the amount and nutrient composition of a meal. This is processed, eventually leading to meal termination. The response of gastric VAs, to food-related stimuli, is under circadian control and fluctuates depending on the time of day. These rhythms are highly correlated with meal size, with a nadir in VA sensitivity and increase in meal size during the dark phase and a peak in sensitivity and decrease in meal size during the light phase in mice. These rhythms are disrupted in diet-induced obesity and simulated shift work conditions and associated with disrupted food intake patterns. In diet-induced obesity the dampened responses during the light phase are not simply reversed by reverting back to a normal diet. However, time restricted feeding prevents loss of diurnal rhythms in VA signalling in high fat diet-fed mice and, therefore, provides a potential strategy to reset diurnal rhythms in VA signalling to a pre-obese phenotype. This review discusses the role of the circadian system in the regulation of gastrointestinal VA signals and the impact of factors, such as diet-induced obesity and shift work, on these rhythms.

Weight loss with or without intragastric balloon causes divergent effects on ghrelin cell expression

Objective

The mechanism of action of intragastric balloons in the treatment of obesity is not fully understood. One of the hypotheses is that balloons might have an effect on the fundus, the area of ghrelin production.

Methods

Participants were randomized to a 13‐week period of sham or balloon treatment followed by a 13‐week period of balloon therapy in everyone. Blood samples for ghrelin levels were taken in the fasting state and after a breakfast at the start, after 13 and 26 weeks. Biopsies for ghrelin cell immunohistochemistry were taken from the fundus at endoscopy.

Results

Seven participants entered the balloon–balloon (BB) group and 11 the sham–balloon (SB) group. Despite a considerable weight loss, a median −17.9 kg (interquartile ranges −23.8 to −0.5) in the BB group and −18.3 kg (−22.7 to −14.7) in the SB group, fasting ghrelin and meal‐induced ghrelin response did not change. In the SB group, the number of ghrelin cells increased significantly (p 0.001) from 110.6 (83.6–118.9) to 160.2 (128.5–223.0) while on sham treatment and returned to initial levels, 116.3 (91.7–146.9) (p 0.001), when they received their first balloon. No significant changes in ghrelin cell numbers were observed in the BB group.

Conclusion

In participants without a balloon, weight loss induced an increase in ghrelin cell numbers in the fundus, which was annulled by the subsequent placement of a balloon. The effect of a balloon might be explained by effects on ghrelin cell numbers or ghrelin cell activity.

The Clinical and Metabolic Effects of Intragastric Balloon on Morbid Obesity and Its Related Comorbidities

Obesity is becoming increasingly prevalent worldwide, and its metabolic sequelae lead to a significant burden on healthcare resources. Options for the management of obesity include lifestyle modification, pharmacological treatment, surgery, and endoscopic bariatric therapies (EBTs). Among these, EBTs are more effective than diet and lifestyle modification and are less invasive than bariatric surgery. In recent years, there have been significant advances in technologies pertaining to EBTs. Of all the available EBTs, there is a significant amount of clinical experience and published data regarding intragastric balloons (IGBs) because of their comparatively long development period. Currently, the United States Food and Drug Administration (FDA) has approved three IGBs, including Orbera (Apollo Endosurgery, Austin, TX, USA), ReShape Duo (ReShape Medical, San Clemente, CA, USA), and Obalon (Obalon Therapeutics, Carlsbad, CA, USA). The aim of this review is to summarize the available literature on the efficacy of IGBs in weight loss and their impact on obesity-related metabolic diseases.

Changes in Time of Gastric Emptying After Surgical and Endoscopic Bariatrics and Weight Loss: A Systematic Review and Meta-Analysis

BACKGROUND & AIMS

Gastric emptying (GE) is involved in the regulation of appetite. We compared times of GE after different bariatric endoscopic and surgical interventions and associations with weight loss.

METHODS

We performed a comprehensive search of publication databases, through September 14, 2018, for randomized and nonrandomized studies reporting outcomes of weight-loss surgeries. Two independent reviewers selected and appraised studies. The outcome of interest was GE T1/2 (min), measured before and after the procedure. A random-effects model was used to pool the mean change in T1/2 (min) after the intervention. We performed a meta-regression analysis to find associations between GE and weight loss. Heterogeneity was calculated using the I2 statistic. Methodologic quality was assessed.

RESULTS

From 762 citations, the following studies were included in our analysis: 9 sleeve gastrectomies, 5 intragastric balloons, and 5 antral botulinum toxins. After sleeve gastrectomy, the pooled mean reduction in GE T1/2 at 3 months was 29.2 minutes (95% CI, 40.9-17.5 min; I2 = 91%). Fluid-filled balloons increased GE T1/2 by 116 minutes (95% CI, 29.4-203.4 min; I2 = 58.6%). Air-filled balloons did not produce a statistically significant difference in GE T1/2. Antral botulinum injections increased GE T1/2 by 9.6 minutes (95% CI, 2.8-16.4 min; I2 = 13.3%). Placebo interventions reduced GE T1/2 by 6.3 minutes (95% CI, 10-2.6 min). Changes in GE were associated with weight loss after sleeve gastrectomy and intragastric balloons, but not botulinum toxin injections.

CONCLUSIONS

In a systematic review and meta-analysis, we found that sleeve gastrectomy reduced GE T1/2 whereas fluid-filled balloons significantly increased GE T1/2. Air-filled balloons do not significantly change the time of GE, which could account for their low efficacy. Antral botulinum toxin injections produced small temporary increases in GE time, which were not associated with weight loss. Changes in GE time after surgical and endoscopic bariatric interventions correlated with weight loss and might be used to select interventions, based on patients' physiology.

Combined effects of cholecystokinin-8 and gastric distension on food intake in humans

In a previous study (Kissileff HR, Carretta JC, Geliebter A, Pi-Sunyer FX. Am J Physiol Regul Integr Comp Physiol 285: R992-R998, 2003), when subthreshold gastric distension (300 ml) and a low dose of cholecystokinin octapeptide (CCK-8) (112 ng/min for 21 min) were concurrently administered to human participants, intake of a test meal was significantly reduced. However, the supra-additive interaction of CCK-8 and gastric distension was not significant. The purpose of the present study was to determine whether a significant interaction would be obtained when CCK-8 and gastric distension were each increased by 50% above levels used in the previous study. Twelve normal-weight, healthy participants were tested four times each with either CCK-8 (168 ng/min for 30 min) or saline infusion crossed with gastric distension (450 ml) or no distension. The combination of CCK-8 and gastric distension reduced food intake by a mean of 405 ± 86 g (SE) in comparison with the saline nondistension condition (P < 0.001), which is a 51% reduction. Although there were some differences in the protocols, the combined effect was double that seen in the previous study. Although the interactive effect was larger [118 ± 109 g (SE)] than it was previously [73 ± 86 (SE)], it was not significant (P = 0.29). There were also reports of a short-lived sick feeling after CCK-8, with and without distension, that was not observed in the previous study. Thus the combination of CCK-8 at 1.5 times threshold and gastric distension at 450 ml (increased from 300 ml) resulted in a combined effect to reduce food intake, which was also 1.5 times its previous value, and thus appears linear.

Just add water: Effects of added gastric distention by water on gastric emptying and satiety related brain activity

BACKGROUND

Gastric distention contributes to meal termination. There is little research on the neural correlates of gastric distention by food. To date, neural measures have not been obtained concurrently with measurements of gastric distention.

OBJECTIVES

1) To study how offering a small versus a large water load following a standardized nutrient load affects gastric distention over time. 2) To assess associations between satiety experiences and brain activity and the degree of gastric distention.

METHOD

19 healthy males (age 22.2 ± 2.5 y, BMI 21.8 ± 1.5 kg/m²) participated in a randomized crossover study with two treatments: ingestion of a 500-kcal 150-mL liquid meal shake followed by a low (LV, 50 mL) or a high volume (HV, 350 mL) water load. At baseline and three times after ingestion satiety was scored, MRI scans were made to determine total gastric content volume (TGV) and functional MRI scans were made to measure cerebral blood flow (CBF).

RESULTS

TGV was significantly higher for HV compared to LV at all time points (p < 0.001) with relative differences between HV and LV of 292 ± 37 mL after ingestion, 182 ± 83 mL at t = 15 min and 62 ± 57 mL at t = 35 min. Hunger decreased (p = 0.023) and fullness increased (p = 0.030) significantly more for HV compared to LV. Ingestion increased CBF in the inferior frontal gyrus and the anterior insula, but there were no differences between treatments. There were no significant correlations between appetite ratings and CBF values.

CONCLUSION

Performing concurrent gastric MRI and CBF measurements can be used to investigate neural correlates of gastric distention. Increased distention did not induce significantly greater brain activation. Future research should further examine the role of the inferior frontal gyrus in satiety.

Obesity treatment by Bioenterics intragastric balloon: Iranian results

We studied the effectiveness, tolerability and safety of Bioenteric Intragastric Balloon (BIB) for treatment of obesity in Iranian population. 52 patients (46 female (88.5%), mean age: 35.5 ±10, mean body weight: 107.6±25.4 kg) referred to two major training hospitals in Tehran, Iran, after evaluation by a multidisciplinary team, underwent endoscopic BIB placement under unconscious sedation. BIB was removed after 6 months and patients were discharged with drug therapy and 1000 kcal diet. Weight and Body Mass Index (BMI) were assessed at baseline, 6 months and 1 year after BIB insertion. The mean weight and BMI at baseline were 107.6±25.4 kg and 39.4±7.9 kg/m2; 6 months after balloon placement, they were 88.7±21.9 kg and 32.5±7.4 kg and 6 months after balloon removal, they were 93.4±21.9kg and 34.85±8.2 kg/m2 respectively. The weight decline was statistically significant throughout the study and follow up with p value <0.001. The most frequent side effects were nausea and vomiting which were resolved in the majority of cases by one week. No major complications, such as death, gastric obstruction, gastric or esophageal perforation, or balloon displacement occurred in our study. BIB is a safe, effective and well-tolerated treatment of obesity, but its effects are temporary, so it should be accompanied and followed by other methods to achieve sustained weight reduction.

Obesity Treatment with Botulinum Toxin-A Is Not Effective: a Systematic Review and Meta-Analysis

The effectiveness of gastric injections of botulinum toxin-A (BTA) as primary treatment for obesity is not well known since results in literature are discrepant. Hence, we aimed to systematically review and meta-analyze the available data to assess the real effect of BTA therapy. We searched MEDLINE, Embase, Cochrane, SCOPUS, EBSCO, LILACS, and BVS. We considered eligible only randomized controlled trials enrolling obese patients comparing BTA versus saline injections. Our initial search identified 8811 records. Six studies fulfilled eligibility criteria. After critical appraisal, two articles were excluded and we meta-analyzed the remainder. The mean difference for absolute weight loss and BMI reduction were 0.12 [CI 95%, - 1.14, 1.38] and - 0.06 [95% CI, - 0.92, 0.81], respectively. Therefore, we concluded that treatment of obesity with BTA is not effective.

Parental beliefs about portion size, not children's own beliefs, predict child BMI

BACKGROUND

Increases in portion size are thought by many to promote obesity in children. However, this relationship remains unclear. Here, we explore the extent to which a child's BMI is predicted both by parental beliefs about their child's ideal and maximum portion size and/or by the child's own beliefs.

METHODS

Parent-child (5-11 years) dyads (N = 217) were recruited from a randomized controlled trial (n = 69) and an interactive science centre (n = 148). For a range of main meals, parents estimated their child's 'ideal' and 'maximum tolerated' portions. Children completed the same tasks.

RESULTS

An association was found between parents' beliefs about their child's ideal (β = .34, p < .001) and maximum tolerated (β = .30, p < .001) portions, and their child's BMI. By contrast, children's self-reported ideal (β = .02, p = .718) and maximum tolerated (β = -.09, p = .214) portions did not predict their BMI. With increasing child BMI, parents' estimations aligned more closely with their child's own selected portions.

CONCLUSIONS

Our findings suggest that when a parent selects a smaller portion for their child than their child self-selects, then the child is less likely to be obese. Therefore, public health measures to prevent obesity might include instructions to parents on appropriate portions for young children.

Decreased Esophageal Sensitivity to Acid in Morbidly Obese Patients: A Cause for Concern?

Background/Aims

To evaluate esophageal sensitivity to acid between morbidly obese (MO) patients and non-MO controls with abnormal esophageal acid exposure.

Methods

We conducted a cross-sectional study of 58 patients: 30 MO (cases) and 28 non-MO (controls). Esophageal symptoms and esophageal sensitivity to 0.1 M hydrochloric acid solution (Bernstein test) were compared between MO and non-MO patients with a prior diagnosis of abnormal esophageal acid exposure.

Results

MO patients were less symptomatic than non-MO controls (14% vs 96%; odds ratio [OR], 0.006; 95% confidence interval [CI], 0.001 to 0.075; p=0.000). MO patients were more likely to present with decreased esophageal sensitivity to the instillation of acid than non-MO controls (57% vs 14%; OR, 8; 95% CI, 1.79 to 35.74; p=0.009). Subgroup analysis revealed no differences in esophageal sensitivity in MO patients with and without abnormal esophageal acid exposure (43% vs 31%; p=0.707).

Conclusions

Silent gastroesophageal reflux disease (GERD) is common among MO individuals, likely due to decreased esophageal sensitivity to acid. The absence of typical GERD symptoms in these patients may delay discovery of precancerous conditions, such as Barrett’s esophagus. We believe that these patients may require a more aggressive diagnostic work-up to rule out the presence of silent GERD.

Neuronal connections of the central amygdalar nucleus with refeeding-activated brain areas in rats

Following fasting, satiety is accompanied by neuronal activation in brain areas including the central amygdalar nucleus (CEA). Since CEA is known to inhibit food intake, we hypothesized that CEA contributes to the termination of meal during refeeding. To better understand the organization of this satiety-related circuit, the interconnections of the CEA with refeeding-activated neuronal groups were elucidated using retrograde (cholera toxin-β subunit, CTB) and anterograde (phaseolus vulgaris leucoagglutinin, PHA-L) tracers in male rats. C-Fos-immunoreactivity was used as marker of neuronal activation. The refeeding-activated input of the CEA primarily originated from the paraventricular thalamic, parasubthalamic and parabrachial nuclei. Few CTB-c-Fos double-labeled neurons were detected in the prefrontal cortex, lateral hypothalamic area, nucleus of the solitary tract (NTS) and the bed nuclei of the stria terminalis (BNST). Only few refeeding-activated proopiomelanocortin-producing neurons of the arcuate nucleus projected to the CEA. Anterograde tract tracing revealed a high density of PHAL-labeled axons contacted with refeeding-activated neurons in the BNST, lateral hypothalamic area, parasubthalamic, paraventricular thalamic and parabrachial nuclei and NTS; a low density of labeled axons was found in the paraventricular hypothalamic nucleus. Chemogenetic activation of the medial CEA (CEAm) inhibited food intake during the first hour of refeeding, while activation of lateral CEA had no effect. These data demonstrate the existence of reciprocal connections between the CEA and distinct refeeding-activated hypothalamic, thalamic and brainstem nuclei, suggesting the importance of short feedback loops in the regulation of satiety and importance of the CEAm in the regulation of food intake during refeeding.

Efficacy of First-Time Intragastric Balloon in Weight Loss: a Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

The intragastric balloon (IGB) is an adjunctive treatment for obesity. This meta-analysis aimed to evaluate the efficacy and safety of IGB treatment by reviewing randomized controlled trials (RCTs).

METHODS

A total of 20 RCTs involving 1195 patients were identified. Weight loss results before and after 3 months were analyzed separately. The weight loss results of patients with and without IGB treatment were compared.

RESULTS

Our meta-analysis calculated the following significant effect sizes: 1.59 and 1.34 kg/m² for overall and 3-month BMI loss, respectively; 14.25 and 11.16 % for overall and >3-month percentage of excess weight loss, respectively; 4.6 and 4.77 kg for overall and 3-month weight loss, respectively; and 2.81, 1.62, and 4.09 % for overall, 3-month, and >3-month percent of weight loss, respectively. A significant effect size was calculated that favored fluid-filled IGBs over air-filled IGBs. Flatulence (8.75 vs. 3.89 %, p = 0.0006), abdominal fullness (6.32 vs. 0.55 %, p = 0.001), abdominal pain (13.86 vs. 7.2 %, p = 0.0001), abdominal discomfort (4.37 vs. 0.55 %, p = 0.006), and gastric ulcer (12.5 vs. 1.2 %, p < 0.0001) were significantly more prevalent among IGB patients than among non-IGB control patients. No mortality was reported from IGB treatment.

CONCLUSION

IGB treatment, in addition to lifestyle modification, is an effective short-term modality for weight loss. However, there is not sufficient evidence confirming its safety or long-term efficacy.

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.

A brief review of salient factors influencing adult eating behaviour

A better understanding of the factors that influence eating behaviour is of importance as our food choices are associated with the risk of developing chronic diseases such as obesity, CVD, type 2 diabetes or some forms of cancer. In addition, accumulating evidence suggests that the industrial food production system is a major contributor to greenhouse gas emission and may be unsustainable. Therefore, our food choices may also contribute to climate change. By identifying the factors that influence eating behaviour new interventions may be developed, at the individual or population level, to modify eating behaviour and contribute to society’s health and environmental goals. Research indicates that eating behaviour is dictated by a complex interaction between physiology, environment, psychology, culture, socio-economics and genetics that is not fully understood. While a growing body of research has identified how several single factors influence eating behaviour, a better understanding of how these factors interact is required to facilitate the developing new models of eating behaviour. Due to the diversity of influences on eating behaviour this would probably necessitate a greater focus on multi-disciplinary research. In the present review, the influence of several salient physiological and environmental factors (largely related to food characteristics) on meal initiation, satiation (meal size) and satiety (inter-meal interval) are briefly discussed. Due to the large literature this review is not exhaustive but illustrates the complexity of eating behaviour. The present review will also highlight several limitations that apply to eating behaviour research.

Effects of Advice to Drink 8 Cups of Water per Day in Adolescents With Overweight or Obesity: A Randomized Clinical Trial

IMPORTANCE

Health care professionals commonly recommend increased water consumption, typically to 8 cups per day, as part of a weight-reducing diet. However, this recommendation is based on limited evidence and virtually no experimental data from the pediatric population.

OBJECTIVE

To compare 2 standardized weight-loss diets among adolescents with overweight or obesity, either with or without additional advice and behavioral support to increase habitual water intake to 8 cups per day.

DESIGN, SETTING, AND PARTICIPANTS

A randomized clinical, parallel-group trial was conducted between February 2, 2011, and June 26, 2014, at Boston Children's Hospital, Boston, Massachusetts, among 38 adolescents with overweight or obesity who reported drinking 4 cups or less of water per day.

INTERVENTIONS

All participants in both groups received similar weight-reducing interventions, differentiated by advice about water intake (the water group received advice to increase water intake to 8 cups per day; the control group did not receive such advice) but controlled for other dietary recommendations and treatment intensity. The interventions included dietary counseling, daily text messages, and a cookbook with health guides. To support adherence to 8 cups of water per day, the water group received well-defined messages about water through counseling and daily text messages, a water bottle, and a water pitcher with filters.

MAIN OUTCOMES AND MEASURES

The primary outcome was 6-month change in body mass index z score. Data analyses followed the intention-to-treat principle.

RESULTS

All 38 participants (27 girls and 11 boys; mean [SD] age, 14.9 [1.7] years) completed the study. Both groups reported drinking approximately 2 cups of water per day at baseline. Self-reported change in water intake at 6 months was greater in the water group (difference from baseline, 2.8 cups per day [95% CI, 1.8 to 3.8]; P < .001) compared with that in the control group (difference from baseline, 1.2 cups per day [95% CI, 0.2 to 2.2]; P = .02) (difference between groups, 1.6 cups per day [95% CI, 0.2 to 3.0 cups per day]; P = .03). The 6-month change in body mass index z score did not differ between the water group (difference from baseline, -0.1 [95% CI, -0.2 to -0.0]; P = .005) and the control group (difference from baseline, -0.1 [95% CI, -0.2 to -0.0]; P = .008) (difference between groups, -0.0 [95% CI, -0.1 to 0.1]; P = .88).

CONCLUSIONS AND RELEVANCE

Advice and behavioral supports to consume 8 cups of water per day in the context of a weight-reducing diet did not affect body weight among adolescents with overweight or obesity. Despite intensive behavior supports, few adolescents achieved the target of 8 cups of water per day. Environmental interventions to reduce barriers to water consumption at school may be necessary in future research of the feasibility and effectiveness to achieve the target of an intake of 8 cups of water per day in adolescents.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01044134.

Endoscopic Bariatric and Metabolic Therapies: New and Emerging Technologies

Endoscopic bariatric and metabolic therapies (EBMT) are a new addition to the treatment arsenal for obesity. These include devices that are placed or removed via flexible endoscopy, and procedures that utilize instruments that require flexible endoscopy for the indications of weight loss or treatment of glucose intolerance (from pre-diabetes to diabetes). The EBMTs are generally divided into gastric and small bowel categories, and although individual EBMTs may have unique mechanisms of action, similar themes in proposed mechanism of action are seen in the gastric and small bowel EBMTs, respectively. In this review we will describe the therapies approved for use in the United States or currently in the process of obtaining approval for use in the United States. We will discuss potential mechanisms of action and examine safety and efficacy data.

Plasticity of gastrointestinal vagal afferent satiety signals

The vagal link between the gastrointestinal tract and the central nervous system (CNS) has numerous vital functions for maintaining homeostasis. The regulation of energy balance is one which is attracting more and more attention due to the potential for exploiting peripheral hormonal targets as treatments for conditions such as obesity. While physiologically, this system is well tuned and demonstrated to be effective in the regulation of both local function and promoting/terminating food intake the neural connection represents a susceptible pathway for disruption in various disease states. Numerous studies have revealed that obesity in particularly is associated with an array of modifications in vagal afferent function from changes in expression of signaling molecules to altered activation mechanics. In general, these changes in vagal afferent function in obesity further promote food intake instead of the more desirable reduction in food intake. It is essential to gain a comprehensive understanding of the mechanisms responsible for these detrimental effects before we can establish more effective pharmacotherapies or lifestyle strategies for the treatment of obesity and the maintenance of weight loss.

Ghrelin, CCK, GLP-1, and PYY(3-36): Secretory Controls and Physiological Roles in Eating and Glycemia in Health, Obesity, and After RYGB

The efficacy of Roux-en-Y gastric-bypass (RYGB) and other bariatric surgeries in the management of obesity and type 2 diabetes mellitus and novel developments in gastrointestinal (GI) endocrinology have renewed interest in the roles of GI hormones in the control of eating, meal-related glycemia, and obesity. Here we review the nutrient-sensing mechanisms that control the secretion of four of these hormones, ghrelin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), and peptide tyrosine tyrosine [PYY(3-36)], and their contributions to the controls of GI motor function, food intake, and meal-related increases in glycemia in healthy-weight and obese persons, as well as in RYGB patients. Their physiological roles as classical endocrine and as locally acting signals are discussed. Gastric emptying, the detection of specific digestive products by small intestinal enteroendocrine cells, and synergistic interactions among different GI loci all contribute to the secretion of ghrelin, CCK, GLP-1, and PYY(3-36). While CCK has been fully established as an endogenous endocrine control of eating in healthy-weight persons, the roles of all four hormones in eating in obese persons and following RYGB are uncertain. Similarly, only GLP-1 clearly contributes to the endocrine control of meal-related glycemia. It is likely that local signaling is involved in these hormones' actions, but methods to determine the physiological status of local signaling effects are lacking. Further research and fresh approaches are required to better understand ghrelin, CCK, GLP-1, and PYY(3-36) physiology; their roles in obesity and bariatric surgery; and their therapeutic potentials.

Gut-brain nutrient sensing in food reward

For the past several decades, vagal and hormonal gut-brain negative feedback signaling mechanisms that promote satiety and subsequent suppression of food intake have been explored. In addition, a separate positive feedback process termed "appetition," involving postoral signaling from the gut to the brain, has been shown to promote food intake and produce flavor-nutrient preference conditioning. Afferent fibers emerging from the vagus nerve form the main pathway by which information is relayed from the abdominal viscera to the hindbrain and eventually other higher brain regions involved in food intake. Using a specialized subdiaphragmatic vagal deafferentation technique, it was observed that gut vagal and splanchnic afferents play a role in the negative feedback control of satiety after nutrient intake; however, these afferents are not required for nutrient reinforcement or flavor-nutrient preference conditioning, thereby highlighting the distinction between the processes of satiation and appetition. By linking these physiological and behavioral processes to a neurochemical mechanism, it was found that striatal dopamine release induced by intragastric glucose infusion is involved in sweet appetite conditioning. The mechanisms underlying appetition are still being investigated but may involve other nondopaminergic neurochemical systems and/or presently undiscovered hormonal mediators. Future work to delineate the biological mechanisms whereby appetition drives increased intake and conditioned food preference in response to ingestion should take a multifaceted approach by integrating hormonal, neurophysiological, and behavioral techniques.

Endoscopic Management

Endoscopic bariatric therapy consists of devices or procedures for primary weight loss or weight regain after Roux-en-Y gastric bypass that are placed or done endoscopically. In most cases, they result in less weight loss, but fewer complications than bariatric surgery; and more weight loss than lifestyle therapy or weight loss medications. These therapies are important advances to treat patients with obesity. This article focuses on therapies or devices with US Food and Drug Administration approval or those with current or planned US pivotal trials.

Observed Variability in Sleeve Gastrectomy Volume and Compliance Does Not Correlate to Postoperative Outcomes

BACKGROUND

Restrictive bariatric procedures reduce gastric capacity as a primary mechanism of action. Intraoperatively, surgeons observe variability in size and compliance of specimens. We hypothesized that higher gastric specimen volume or tissue compliance would respond better to restrictive procedures.

MATERIALS AND METHODS

Consecutive patients undergoing laparoscopic sleeve gastrectomy between September 2012 and September 2013 were enrolled. Specimens were insufflated at graduated pressure points creating pressure volume curves, and compliance was calculated. Postoperative weight loss and a hunger scores were recorded. Correlations were determined by Spearman correlation.

RESULTS

Eighty-four patients consented to enrollment. Mean age, weight, and body mass index (BMI) were 45 ± 12 years, 126 ± 23 kg, and 45.4 ± 6 m/kg2, respectively. The resected specimens varied in insufflated capacity from 0.3 to 1.8 (0.71 ± 0.32) L and compliance varied from 14.3 to 85.7 (36.1 ± 14.7) cc/mm Hg. Male patients had a larger greater curvature length (GCL) (P < 0.001), staple line length (SLL) (P = 0.03), gastric volume (GV) (P = 0.002), and gastric compliance (GC) (P < 0.001). Neither GV nor GC correlated to excess body weight loss (EBWL%) as hypothesized. There was an inverse correlation between hunger score and GV (P = 0.010). The mean 1-month, 3-month, 6-month, and 12-month EBWL was 17.4%, 33.2%, 43.7%, and 54.1%, respectively. Follow-up was 71.4% at 1 month, 39.3% at 3 months, 54.8% at 6 months, and 42.9% at 12 months.

CONCLUSIONS

Sleeve gastrectomy specimens exhibit nearly 6-fold variability in both volume and compliance. A large GC is anticipated in male and tall subjects. These observations do not appear to be correlated to %EBWL.

The role of alginates in regulation of food intake and glycemia: a gastroenterological perspective

Regulation of food intake through modulation of gastrointestinal responses to ingested foods is an ever-growing component of the therapeutic approaches targeting the obesity epidemic. Alginates, viscous and gel-forming soluble fibers isolated from the cell wall of brown seaweeds and some bacteria, are recently receiving considerable attention because of their potential role in satiation, satiety, and food intake regulation in the short term. Enhancement of gastric distension, delay of gastric emptying, and attenuation of postprandial glucose responses may constitute the basis of their physiological benefits. Offering physical, chemical, sensorial, and physiological advantages over other viscous and gel-forming fibers, alginates constitute promising functional food ingredients for the food industry. Therefore, the current review explores the role of alginates in food intake and glycemic regulation, their underlying modes of action and their potential in food applications.

Upper gastrointestinal sensitivity to meal-related signals in adult humans - relevance to appetite regulation and gut symptoms in health, obesity and functional dyspepsia

Both the stomach and small intestine play important roles in sensing the arrival of a meal, and its physico-chemical characteristics, in the gastrointestinal lumen. The presence of a meal in the stomach provides a distension stimulus, and, as the meal empties into the small intestine, nutrients interact with small intestinal receptors, initiating the release of gut hormones, associated with feedback regulation of gastrointestinal functions, including gut motility, and signaling to the central nervous system, modulating eating behaviours, including energy intake. Lipid appears to have particularly potent effects, also in close interaction with, and modulating the effects of, gastric distension, and involving the action of gut hormones, particularly cholecystokinin (CCK). These findings have not only provided important, and novel, insights into how gastrointestinal signals interact to modulate subjective appetite perceptions, including fullness, but also laid the foundation for an increasing appreciation of the role of altered gastrointestinal sensitivities, e.g. as a consequence of excess dietary intake in obesity, or underlying the induction of gastrointestinal symptoms in functional dyspepsia (a condition characterized by symptoms, including bloating, nausea and early fullness, amongst others, after meals, particularly those high in fat, in the absence of any structural or functional abnormalities in the gastrointestinal tract). This paper will review the effects of dietary nutrients, particularly lipid, on gastrointestinal function, and associated effects on appetite perceptions and energy intake, effects of interactions of gastrointestinal stimuli, as well as the role of altered gastrointestinal sensitivities (exaggerated, or reduced) in eating-related disorders, particularly obesity and functional dyspepsia.

Consequences of bariatric surgery on oesophageal function in health and disease

Obesity is a continuing epidemic with substantial associated morbidity and mortality. Owing to the limitations of lifestyle modifications and pharmacological options, bariatric surgery has come to the forefront as an efficient method of achieving sustained weight loss and decreasing overall mortality in comparison with nonsurgical interventions. The most frequently performed bariatric operations are either purely restrictive, such as laparoscopic adjustable gastric band (LAGB) and laparoscopic sleeve gastrectomy (LSG), or restrictive-malabsorptive, such as the Roux-en-Y gastric bypass (RYGB). Each operation results in weight loss, but can also have unintended effects on the health of the oesophagus. Specifically, operations might lead to oesophageal dilation or the development of GERD. LAGB is the best-studied procedure with notable evidence for postoperative worsening of GERD and pseudo-achalasia, which increases lower oesophageal pressure and causes aperistalsis. In some studies, LSG initiates not only a worsening of GERD, but also the formation of de novo GERD in patients without preoperative GERD symptoms. RYGB demonstrates the most profound evidence for improvement of GERD symptoms and preservation of oesophageal motility. Future high-quality studies will be required to better understand the interaction between bariatric surgery and oesophageal disease.

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.

Aerated drinks increase gastric volume and reduce appetite as assessed by MRI: a randomized, balanced, crossover trial

BACKGROUND

Compared with nonaerated, isocaloric controls, aerated foods can reduce appetite throughout an entire dieting day. Increased gastric volumes and delayed emptying are possible but unexplored mechanisms.

OBJECTIVE

We tested the hypothesis that aerated drinks (foams) of differing gastric stability would increase gastric distension and reduce appetite compared with a control drink.

DESIGN

In a randomized, balanced, crossover trial, 18 healthy male participants consumed the following 3 skimmed-milk-based test products (all 110 kcal): 2 drinks aerated to foams by whipping (to 490 mL), one drink that was stable in the stomach [stable foam (SF)], and one drink that was less stable in the stomach [less-stable foam (LSF)], and a nonaerated drink [liquid control (LC); 140 mL]. Over 4 h, stomach contents (foam, air, and liquid) were imaged using magnetic resonance imaging (MRI), and self-reported appetite ratings were collected and quantified by the area under the curve or time to return to baseline (TTRTB).

RESULTS

Compared with the LC, both foams caused significantly increased gastric volumes and reduced hunger (all P < 0.001). Compared with the LSF, SF further produced a significantly slower decrease in the total gastric content (P < 0.05) and foam volume (P < 0.0001) and a longer TTRTB (197 compared with 248 min, respectively; P < 0.05), although the hunger AUC was not statistically different. Results for other appetite scales were similar.

CONCLUSIONS

With this MRI trial, we provide novel insights on the gastrointestinal behavior of aerated drinks by measuring separate volumes of foam, liquid, and air layers in the stomach. Appetite suppression induced by foams could largely be explained by effects on gastric volumes and emptying, which may be further enhanced by foam stability. This trial was registered at clinicaltrials.gov as NCT01690182.

Sustained hunger suppression from stable liquid food foams

OBJECTIVE

Simple aeration of food matrices with gas has previously been shown to generate immediate suppression of appetite, though duration of effects has not been shown. This research tested whether liquids aerated with nitrous oxide (N2 O) to achieve high in-body stability could produce enhanced and sustained effects on eating motivations.

METHODS

In two randomized cross-over studies, appetite ratings were collected for 240 min. In Study 1, 24 volunteers consumed a full portion liquid (325 ml, 190 kcal) or aerated (1,000 ml, 190 kcal) drink at 0 min, or half portions of liquid (162 ml, 95 kcal) or aerated (500 ml, 95 kcal) drink at 0 and 120 min. In Study 2, assessing the effect of N2 O itself, 23 volunteers consumed water saturated with N2 O or with CO2 10 min after a mini-drink (180 kcal). Appetite was quantified by area-under-the curve (AUC) and time-to-return-to-baseline (TTRTB).

RESULTS

Full- and half-size aerated drinks decreased hunger AUC over 4 h by 26 and 50% (P < 0.0001) versus the respective liquid versions. Effects were also sustained significantly longer (TTRTB from 203 to 335 and from 173 to 286 min, respectively). In Study 2, N2 O and CO2 had similar effects on appetite ratings.

CONCLUSIONS

Aeration of foods using appropriate microstructural design has a powerful effect on eating motivations.

Endoscopic treatment: the past, the present and the future

The obesity epidemic asks for an active involvement of gastroenterologists: many of the co-morbidities associated with obesity involve the gastrointestinal tract; a small proportion of obese patients will need bariatric surgery and may suffer from surgical complications that may be solved by minimally invasive endoscopic techniques; and finally, the majority will not be eligible for bariatric surgery and will need some other form of treatment. The first approach should consist of an energy-restricted diet, physical exercise and behaviour modification, followed by pharmacotherapy. For patients who do not respond to medical therapy but are not or not yet surgical candidates, an endoscopic treatment might look attractive. So, endoscopic bariatric therapy has a role to play either as an alternative or adjunct to medical treatment. The different endoscopic modalities may vary in mechanisms of action: by gastric distension and space occupation, delayed gastric emptying, gastric restriction and decreased distensibility, impaired gastric accommodation, stimulation of antroduodenal receptors, or by duodenal exclusion and malabsorption. These treatments will be discussed into detail.

Fasting and meal-suppressed ghrelin levels before and after intragastric balloons and balloon-induced weight loss

BACKGROUND

Intragastric balloons may be an option for obese patients with weight loss failure. Its mode of action remains enigmatic. We hypothesised depressed fasting ghrelin concentrations and enhanced meal suppression of ghrelin secretion by the gastric fundus through balloon contact and balloon-induced delayed gastric emptying.

METHODS

Patients were randomised to a 13-week period of sham or balloon treatment, followed by a 13-week period of balloon treatment in everyone. Blood samples for ghrelin measurement were taken in the fasting state and every 15 min for 1 h after a breakfast meal at the start, after 13 weeks and after 26 weeks. Patients filled out scales to assess satiety and kept a food diary.

RESULTS

Forty obese patients (BMI 43.1 kg/m(2)) participated. At the start, fasting ghrelin values were low with a blunted ghrelin response to a test meal. The presence of a balloon had no influence on fasting or meal-suppressed ghrelin concentrations. Despite a weight loss of 10 % after 13 weeks and 15 % after 26 weeks, fasting ghrelin concentrations did not change; neither did the ghrelin response to a meal. No relation was found between ghrelin and insulin, satiety, intermeal interval, the number of meals or subsequent energy intake. Ghrelin concentrations were more suppressed with greater weight loss or with balloons located in the fundus.

CONCLUSIONS

Ghrelin concentrations did not change by balloon treatment after 13 and 26 weeks and, unexpectedly, did not rise despite substantial weight loss and negative energy balance. This suppression might be of benefit in the maintenance of weight loss but could not be ascribed to the balloon treatment.

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.

Efficacy of a laparoscopic gastric restrictive device in an obese canine model

BACKGROUND

Bariatric surgery using laparoscopic techniques is the most effective treatment for morbid obesity. The objective of the study is to assess the safety and efficacy of a novel laparoscopic reversible gastric restrictive (RGR) device in a group of obese dogs. An implant was also performed in a cadaver to assess implant feasibility in a human.

METHODS

Four obese mongrel dogs were subjected to RGR implantation for 3 months followed by recovery for an additional 6 weeks after device removal. Food intake, body weight, radiographic barium imaging, and gastric endoscopy were used to monitor RGR performance before implant, after implant, and implant removal. An additional RGR laparoscopic implantation procedure was performed in a human cadaver.

RESULTS

The implanted obese dogs exhibited a significant decrease in food intake and body weight over 3 months with the RGR device. The reduction of food intake was sustained at an average of 46 % after implant and the excess weight loss reached an average of 75 % at the end of 12 weeks with recovery to approximately 78 % of baseline after 6 weeks of implant removal. Barium imaging and gastric endoscopy both confirmed passage for food through the restrictive device channel in the stomach. The RGR device was successfully implanted laparoscopically on the cadaver stomach in less than an hour.

CONCLUSIONS

The RGR device is laparoscopically deliverable and removable with effective and sustainable weight loss over a 12-week period in an obese dog model. The implant is also technically feasible in man.

The effects of carbonated water upon gastric and cardiac activities and fullness in healthy young women

Although previous reports suggested that carbonated water drinking was effective against gastrointestinal symptoms, there is little information about the effects of carbonated water on gastric and appetite sensation. We therefore investigated the effect of carbonated water on short-term fullness with respect to gastric and cardiac responses in 19 healthy young women. Each subject was tested on three separate days at approximately 9 a.m. after an overnight fast. Gastric motility, evaluated by electrogastrography (EGG) and heart rate (HR), was measured for 20 min in the fasting state and 40 min after ingestion of water. Preloads consisted of an equivalent amount (250 mL) of water (W) or carbonated water (CW) and no drinking (blank). Fullness scores were measured using visual analog scales. To determine gastric motility, we assessed the component of bradygastria (1-2 cycles/min [cpm]), normogastria (2-4 cpm), tachygastria (4-9 cpm), and dominant frequency of the EGG power spectrum. After ingestion of CW, significant increases in fullness scores were observed compared with W. All postprandial EGG powers were significantly greater than preprandial, but no group difference was found. However, a dominant frequency tended to shift toward a lower band after ingestion of W. A significantly higher HR was found following consumption of CW as opposed to W. Multiple regression analysis revealed that increased HR was a significant variable contributing to the variances in fullness after ingestion of CW at 40 min. Our data suggest that CW may induce a short-term, but significant, satiating effect through enhanced postprandial gastric and cardiac activities due possibly to the increased sympathetic activity and/or withdrawal of parasympathetic activity.

Endoscopy in the management of obesity

Obesity affects more than one third of adults in the United States and is associated with increased morbidity, mortality, and health care costs compared with normal weight adults. Current therapies include medical management consisting of therapeutic lifestyle change and pharmacotherapy, which has limited effectiveness, and bariatric surgery, which is currently the most effective therapy, but is limited by complications, long-term weight regain, and limited access. Endoscopic therapies are currently under investigation to treat weight regain after bariatric surgery and as a primary treatment for obesity, addressing the current gap in the treatment of obesity.

The role of the stomach in the control of appetite and the secretion of satiation peptides

It is widely accepted that gastric parameters such as gastric distention provide a direct negative feedback signal to inhibit eating; moreover, gastric and intestinal signals have been reported to synergize to promote satiation. However, there are few human data exploring the potential interaction effects of gastric and intestinal signals in the short-term control of appetite and the secretion of satiation peptides. We performed experiments in healthy subjects receiving either a rapid intragastric load or a continuous intraduodenal infusion of glucose or a mixed liquid meal. Intraduodenal infusions (3 kcal/min) were at rates comparable with the duodenal delivery of these nutrients under physiological conditions. Intraduodenal infusions of glucose elicited only weak effects on appetite and the secretion of glucagon-like peptide-1 (GLP-1) and peptide YY (PYY). In contrast, identical amounts of glucose delivered intragastrically markedly suppressed appetite (P < 0.05) paralleled by greatly increased plasma levels of GLP-1 and PYY (≤3-fold, P < 0.05). Administration of the mixed liquid meal showed a comparable phenomenon. In contrast to GLP-1 and PYY, plasma ghrelin was suppressed to a similar degree with both intragastric and intraduodenal nutrients. Our data confirm that the stomach is an important element in the short-term control of appetite and suggest that gastric and intestinal signals interact to mediate early fullness and satiation potentially by increased GLP-1 and PYY secretions.

Repeated gastric distension alters food intake and neuroendocrine profiles in rats

The consumption of a large food bolus leads to stomach distension. Gastric distension potently signals the termination of a meal by stimulating gastric mechanoreceptors and activating neuroendocrine circuitry. The ability to terminate a meal is altered in disorders such as bulimia nervosa (BN), binge-eating disorder (BED) and certain subtypes of obesity in which large quantities of food are frequently ingested. When a large meal is consumed, the stomach is rapidly stretched. We modeled this rapid distension of the stomach in order to determine if the neuroendocrine abnormalities present in these disorders, including increased gastric capacit3y, leptin dysregulation, and alterations in neuropeptide Y (NPY), and proopiomelanocortin (POMC) expression, were influenced by the rapid stretch aspect of repeatedly consuming a large meal. To test the effects of repeated gastric distension (RGD) on neuroendocrine factors involved in energy homeostasis, a permanent intra-gastric balloon was implanted in rats, and briefly inflated daily for 4 weeks. Though body weights and daily food intakes remained equivalent in RGD and control rats, a significant delay in the onset of feeding was present during the first and second, but not the third and fourth weeks of inflations. Despite equivalent body weights and daily caloric consumption, RGD animals had significantly decreased leptin levels (p<0.05), and tended to have increased fasting arcuate NPY levels (p=0.08), which were suppressed more than control animals following food intake (control and RGD decreases from baseline were 184.95% and 257.42%, respectively). NPY expression in the nucleus of the solitary tract followed a similar pattern. These data demonstrate that the act of regularly distending the stomach can have effects on the regulation of energy balance that are independent from those related to caloric consumption, and may be related to disorders such as BN, BED, and certain types of obesity in which meal termination is impaired.

Could the mechanisms of bariatric surgery hold the key for novel therapies? report from a Pennington Scientific Symposium

Bariatric surgery is the most effective method for promoting dramatic and durable weight loss in morbidly obese subjects. Furthermore, type 2 diabetes is resolved in over 80% of patients. The mechanisms behind the amelioration in metabolic abnormalities are largely unknown but may be due to changes in energy metabolism, gut peptides and food preference. The goal of this meeting was to review the latest research to better understand the mechanisms behind the 'magic' of bariatric surgery. Replication of these effects in a non-surgical manner remains one of the ultimate challenges for the treatment of obesity and diabetes. Promising data on energy metabolism, gastrointestinal physiology, hedonic response and food intake were reviewed and discussed.

Endoscopic solutions for weight loss

PURPOSE OF REVIEW

Gastroenterologists will likely play a critical role in the treatment of obesity and its comorbidities, as novel endoluminal approaches demonstrate their safety and efficacy over the coming years. Understanding the relative advantages and shortcomings of the endoscopic tools and procedures currently under investigation will provide the gastroenterologist with valuable insight into the future of endoscopic procedures for weight loss.

RECENT FINDINGS

Endoscopic restrictive procedures, intestinal sleeves, and intragastric balloons have demonstrated short-term efficacy in inducing weight reduction and in reversing the comorbidities of obesity with an acceptable risk profile. Several endoscopic tools have also demonstrated effectiveness as revisional tools for reversing weight gain after bariatric surgery.

SUMMARY

A plethora of endoscopic tools and procedures are under investigation for primary and revisional obesity management, and these may offer new weight loss options to a variety of different patient populations.

Intragastric balloon therapy in the management of obesity: why the bad wrap?

For the first time in the history of the United States, in the 21st century, there may be a decline in life expectancy, as a result of the increasing rate of obesity. It is known that even the modest reduction of 10% of excess body weight significantly reduces obesity-associated comorbidities. Conservative measures such as diet and exercise seldom give durable results in the long term. Bariatric surgery has been shown to achieve durable weight loss but is not without significant risks and complications. As a result, greater focus has turned toward minimally invasive endoscopic therapies for the management of obesity. There have been multiple reports of creative endoscopic devices and techniques in the literature, but most have only demonstrated early pilot data. By far, the most widely studied of the minimally invasive endoscopic therapies for obesity is the gastric balloon. Now obsolete, the Garren-Edwards gastric bubble was removed from the market in the United States after several sham-controlled studies showed that diet and behavior modification were equally efficacious and that the device was associated with a prohibitive number of complications. However, the concept and technique of intragastric balloon placement has evolved considerably since that time, and we now have data on nearly 3,000 patients who have undergone placement of the BioEnterics Intragastric Balloon (Carpenteria, CA) worldwide. The balloon is approved as part of a multifaceted approach to obesity in many countries and has been shown to result in at least a 10% excess weight loss durable over 1 year. However, the device is not yet approved for use in the United States. In this article, the authors review the efficacy, indications, complications, and potential uses for the intragastric balloon. The intragastric balloon might be the best start as gastroenterologists in the United States begin to play an increasing role in the treatment of the obesity pandemic.