Relationship of body weight with gastrointestinal motor and sensory function: studies in anorexia nervosa and obesity

Are you how you eat? Aspects of self-awareness in eating disorders

Eating disorders (ED) are severe psychiatric disorders characterized by dysfunctional behaviors related to eating or weight control, with profound impacts on health, quality of life, and the financial burden of affected individuals and society at large. Given that these disorders involve disturbances in self-perception, it is crucial to comprehend the role of self-awareness in their prevalence and maintenance. This literature review presents different self-awareness processes, discussing their functioning across different levels of complexity. By deconstructing this concept, we can gain a better understanding of how each facet of self and personality relates to the symptoms of these disorders. Understanding the absence or impairment of self-awareness in ED holds significant implications for diagnosis, treatment, and overall management. By recognizing and comprehending the characteristics of self-awareness, clinicians can develop tailored interventions and evidence-based treatments for individuals with ED. Furthermore, this narrative review underscores the importance of considering temperament and personality factors in the context of ED, as temperament traits and personality characteristics may interact with self-awareness processes, influencing the development and maintenance of ED. Ultimately, the results highlight the pressing need for further research on the development of effective interventions and support strategies grounded in the aspects of self-awareness mechanisms for individuals affected by these disorders.

Understanding the gastrointestinal tract in obesity: From gut motility patterns to enzyme secretion

BACKGROUND AND PURPOSE

The pathophysiology of obesity has been the product of extensive research, revealing multiple interconnected mechanisms contributing to body weight regulation. The regulation of energy balance involves an intricate network, including the gut-neuroendocrine interplay. As a consequence, research on the gut-brain-microbiota axis in obesity has grown extensively. The physiology of the gastrointestinal tract, far from being underexplored, has significant implications for the development of specific complications in people living with obesity across the fields of gastroenterology, nutrition, and pharmacology. Clinical research indicates higher fasting bile acids serum levels, and blunted postprandial increases in bilious secretions in people living with obesity. Findings are less straightforward for the impact of obesity on gastric emptying with various studies reporting accelerated, normal, or delayed gastric emptying rates. Conversely, the effect of obesity on gastrointestinal pH, gastrointestinal transit, and gastric and pancreatic enzyme secretion is largely unknown. In this review, we explore the current evidence on the gastrointestinal physiology of obesity.

Microbiota in anorexia nervosa: potential for treatment

Anorexia nervosa (AN) is characterised by the restriction of energy intake in relation to energy needs and a significantly lowered body weight than normally expected, coupled with an intense fear of gaining weight. Treatment of AN is currently based on psychological and refeeding approaches, but their efficacy remains limited since 40% of patients after 10 years of medical care still present symptoms of AN. The intestine hosts a large community of microorganisms, called the "microbiota", which live in symbiosis with the human host. The gut microbiota of a healthy human is dominated by bacteria from two phyla: Firmicutes and, majorly, Bacteroidetes. However, the proportion in their representation differs on an individual basis and depends on many external factors including medical treatment, geographical location and hereditary, immunological and lifestyle factors. Drastic changes in dietary intake may profoundly impact the composition of the gut microbiota, and the resulting dysbiosis may play a part in the onset and/or maintenance of comorbidities associated with AN, such as gastrointestinal disorders, anxiety and depression, as well as appetite dysregulation. Furthermore, studies have reported the presence of atypical intestinal microbial composition in patients with AN compared with healthy normal-weight controls. This review addresses the current knowledge about the role of the gut microbiota in the pathogenesis and treatment of AN. The review also focuses on the bidirectional interaction between the gastrointestinal tract and the central nervous system (microbiota-gut-brain axis), considering the potential use of the gut microbiota manipulation in the prevention and treatment of AN.

The transit of oral premedication beyond the stomach in patients undergoing laparoscopic sleeve gastrectomy: a retrospective observational multicentre study

BACKGROUND

Antiemetic and analgesic oral premedications are frequently prescribed preoperatively to enhance recovery after laparoscopic sleeve gastrectomy. However, it is unknown whether these medications transit beyond the stomach or if they remain in the sleeve resection specimen, thereby negating their pharmacological effects.

METHODS

A retrospective cohort study was performed on patients undergoing laparoscopic sleeve gastrectomy and receiving oral premedication (slow-release tapentadol and netupitant/palonosetron) as part of enhanced recovery after bariatric surgery program. Patients were stratified into the Transit group (premedication absent in the resection specimen) and Failure-to-Transit group (premedication present in the resection specimen). Age, sex, body mass index, and presence of diabetes were compared amongst the groups. The premedication lead time (time between premedications' administration and gastric specimen resection), and the premedication presence or absence in the specimen was evaluated.

RESULTS

One hundred consecutive patients were included in the analysis. Ninety-nine patients (99%) were morbidly obese, and 17 patients (17%) had Type 2 diabetes mellitus. One hundred patients (100%) received tapentadol and 89 patients (89%) received netupitant/palonosetron. One or more tablets were discovered in the resected specimens of 38 patients (38%). No statistically significant differences were observed between the groups regarding age, sex, diabetes, or body mass index. The median (Q1‒Q3) premedication lead time was 80 min (57.8‒140.0) in the Failure-to-Transit group and 119.5 min (85.0‒171.3) in the Transit group; P = 0.006. The lead time required to expect complete absorption in 80% of patients was 232 min (95%CI:180‒310).

CONCLUSIONS

Preoperative oral analgesia and antiemetics did not transit beyond the stomach in 38% of patients undergoing laparoscopic sleeve gastrectomy. When given orally in combination, tapentadol and netupitant/palonosetron should be administered at least 4 h before surgery to ensure transition beyond the stomach. Future enhanced recovery after bariatric surgery guidelines may benefit from the standardization of premedication lead times to facilitate increased absorption.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry; number ACTRN12623000187640; retrospective registered on 22/02/2023.

Risk of loss to follow-up among tuberculosis patients in South Korea: whom should we focus on?

Introduction

In South Korea, public-private mix (PPM) has been a key strategy in national tuberculosis (TB) control program. This study aimed to identify rate of loss to follow-up (LTFU) among TB patients in nationwide PPM institutions and their risk factors.

Methods

A nationwide prospective observational study including drug susceptible TB patients diagnosed from the 1st day to the 10th day of every month between July 2018 and December 2020 in PPM institutions was designed. Multivariable survival models in which death and failure were designated as events with competing risk were used to investigate risk factors for LTFU.

Results

A total of 14,942 patients were included. Of them, 356 (2.4%) had an LTFU. Risk factors for LTFU were: underweight patients (adjusted hazard ratio (aHR): 1.47, 95% CI: 1.12-1.92), patients living alone (aHR: 1.43, 95% CI: 1.16-1.76), heavy drinkers (aHR: 1.67, 95% CI: 1.16-2.39), those with malignancy (aHR: 1.49, 95% CI: 1.07-2.05), foreigners (aHR: 5.96, 95% CI: 4.51-7.89), and those with previous TB history reported as an unfavorable outcome (aHR: 4.43, 95% CI: 2.77-7.08). Effect of age on LTFU was not significant. Brief interruption of anti-TB treatment (less than two months) in current session was associated with subsequent LTFU [adjusted odds ratio: 13.09 (10.29-16.66)].

Conclusion

Identifying vulnerability of patients such as living alone, being heavy alcoholics, being foreigners or having previous TB history reported as an unfavorable outcome is required. Thorough case management for these vulnerable groups could be feasible with collaboration between public and private sectors.

Pharmacokinetics of obese adults: Not only an increase in weight

Obesity is a pathophysiological state defined by a body mass index > 30 kg/m2 and characterized by an adipose tissue accumulation leading to an important weight increased. Several pathologies named comorbidities such as cardiovascular disease, type 2 diabetes and cancer make obesity the fifth cause of death in the world. Physiological changes impact the four main phases of pharmacokinetics of some drugs and leads to an inappropriate drug-dose. For absorption, the gastrointestinal transit is accelerated, and the gastric empty time is shortened, that can reduce the solubilization and absorption of some oral drugs. The drug distribution is probably the most impacted by the obesity-related changes because the fat mass (FM) increases at the expense of the lean body weight (LBW), leading to an important increase of the volume of distribution for lipophilic drugs and a low or moderately increase of this parameter for hydrophilic drugs. This modification of the distribution may require drug-dose adjustments. By various mechanisms, the metabolism and elimination of drugs are impacted by obesity and should be considered as similar or lower than that non-obese patients. To better understand the necessary drug-dose adjustments in obese patients, a narrative review of the literature was conducted to highlight the main elements to consider in the therapeutic management of adult obese patients.

Examination of the two-step water load test as a measure of gastric interoception and associations with eating and weight/shape concerns in a nonclinical sample

OBJECTIVE

The current study extended research examining the validity of the two-step Water Load Test (WLT-II), an objective, laboratory-based measure of gastric interoception, by investigating the validity of the WLT-II in a nonclinical sample and testing its contribution to the prediction of eating and weight/shape concerns.

METHODS

Participants (n = 129, 73.6% cisgender female, M = 20.13 years old) completed the WLT-II Questionnaire and two-step WLT-II, as well as self-report measures of eating and weight/shape concerns (Eating Disorder Examination Questionnaire; EDE-Q) and interoception (Multidimensional Assessment of Interoceptive Awareness-2; Intuitive Eating Scale-2 Reliance on Hunger and Satiety), in the lab at a large southeastern university. Data analysis included repeated measures ANOVA, correlations, and a series of hierarchical linear regressions.

RESULTS

Participants reported considerably more discomfort after the "maximum fullness" trial compared to the "satiation" trial. The WLT-II's objective measure of gastric interoception (sat_%) was not significantly correlated with the self-report measures of interoception and did not predict EDE-Q Dietary Restraint, Eating Shame, or Weight/Shape Concerns. Unexpectedly, greater gastric sensitivity was associated with less EDE-Q Preoccupation/Restriction. Exploratory analyses suggested a possible nonlinear association.

DISCUSSION

These results support the validity of the WLT-II in its ability to create, measure, and distinguish between the states of satiation and maximum fullness. However, results also suggest additional work is needed to better understand what the WLT-II's sat_% measure is capturing, as well as investigate potential nonlinear associations of the WLT-II with disordered eating.

PUBLIC SIGNIFICANCE

Interoception, or the processing of internal body signals, shows important links to disordered eating. Despite the clear relevance of gastric interoception to disordered eating-such as the ability to detect satiety signals-existing research has relied on general, self-report measures of interoception. This study examined the utility of a laboratory-based measure of gastric interoception. Results suggested mixed support for its validity and utility for predicting eating and weight/shape concerns in a nonclinical population.

Effect of Sitagliptin Versus Glibenclamide on Glycemic Markers, Lipid Profile Inflammatory and Oxidative Stress Factors in Type 2 Diabetes Patients: a Double-Blinded Randomized Controlled Trial

Objectives:Diabetes mellitus is leading to chronic complications, including cardiovascular diseases. The aim of this study was to compare the effect of Sitagliptin and Glibenclamide on glycemic markers, lipid profile inflammatory, and oxidative stress factors in type 2 diabetes patients. Methods: This double-blinded randomized controlled trial was performed on patients with type 2 diabetes mellitus (n=54). The treatment group (27 patients) received 100 mg of Sitagliptin once daily + 500 mg Metformin twice daily, orally, for 12 weeks, and the control group (27 patients) was given 5 mg of Glibenclamide once daily + 500 mg Metformin twice daily, also orally, for 12 weeks. Serum levels of tumor necrosis factor alpha (TNF-α), high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), lipid profile [cholesterol, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), triglyceride (TG)], fasting blood sugar (FBS) and hemoglobin A1C (HbA1c), body weight, and body mass index (BMI) were measured before and after the study. Results:In both groups, the FBS level was significantly reduced from baseline (P=0.03 in the Sitagliptin group and P=0.02 in the Glibenclamide one). The percent of HbA1c was also significantly reduced from baseline in both the Sitagliptin group (P=0.01) and the Glibenclamide one (P=0.008). However, comparing the groups, these changes were not different. In the Sitagliptin group, IL-6 was significantly reduced from baseline (P=0.01) as well as in comparison with the Glibenclamide group (P=0.001). The TG level was significantly lower than the baseline in the Sitagliptin group (P=0.03), so changes between groups were significant (P=0.04). Weight and BMI were significantly increased from baseline in the Glibenclamide group (P=0.02 and P=0.03, respectively), and their changes between the two groups were also significant (P=0.001). Conclusion:These finding support the favorable effects of Sitagliptin on cardiovascular risks beyond its advantages on insulin-glucose hemostasis in patients with type 2 diabetes.

Quantification of gastric emptying with magnetic resonance imaging in healthy volunteers: A systematic review

BACKGROUND

Several magnetic resonance imaging (MRI) protocols have been used to assess gastric emptying (GE) with MRI. This systematic review summarizes the current literature on the topic. The aim was to provide an overview of the available imaging protocols and underline the items that appear most agreed upon and those that deserve further investigation.

METHODS

According to PRISMA guidelines, two independent reviewers conducted a systematic literature search with a pre-specified strategy in different databases. Peer-reviewed articles that utilized MRI techniques to assess GE in healthy volunteers (HVs) were included. The quality and the outcomes of the studies were reported and analyzed.

KEY RESULTS

The literature search yielded 30 studies (531 HVs, weighted mean age 27.4, weighted mean body mass index 23.0 kg/m² ), T2-weighted sequences, balanced turbo field echo, and balanced gradient echo were evenly utilized, with volunteers in the supine position (74% of the studies). After overnight fasting, both liquid (56%) and mixed (44%) meals were equally utilized. Segmentation of the volumes was predominantly performed manually (63%) with a reported mean T50 ranging from 7 to 330 min.

CONCLUSIONS & INFERENCES

As observed in this systematic review, MRI is a flexible tool for assessing GE. Different protocols were analyzed, showing an equal capacity to assess the GE. However, many items in these protocols still require further investigation to obtain a common standard and increase this assessment quality.

Association Between Food Intake and Gastrointestinal Symptoms in Patients With Obesity

BACKGROUND AND AIMS

Hunger, satiation, postprandial satiety, and hedonic eating constitute key food intake parameters. We aim to study whether these symptoms are associated with gastrointestinal symptoms (GIS) in patients with obesity.

METHODS

This is a cross-sectional study of patients with obesity. Patients completed the following validated biomarkers and questionnaires: hunger was measured via visual analog scale (100 mm) following a standard meal, satiation was measured via ad libitum meal (calories to fullness; kcal), postprandial satiety was measured via gastric emptying scintigraphy (T_1/2; mins), and hedonic eating was measured via the Hospital Anxiety and Depression Scale questionnaire. Participants completed the abridged Bowel Disease Questionnaire to evaluate their GIS. We calculated the odds ratios (ORs) adjusted for sex, weight, and age between food intake parameters <25^th or >75^th percentile observed in a prior cohort of 450 participants with obesity and GIS.

RESULTS

A total of 274 participants (41 ± 10 [SD] years, 75% females, body mass index 39 ± 8 kg/m²) were included in the analysis. Increased hunger was associated with a lower prevalence of lumpy stools (OR = 0.18, P = .02). Satiation was associated with abdominal pain/discomfort (relieved by defecation [OR = 2.4, P = .02] or associated with change in stool consistency [OR = 2.92, P < .01]), loose/watery stools (OR = 2.09, P = .02), and bloating (OR = 2.49, P < .01). Abnormal postprandial satiety was associated with bloating (OR = 2.26, P < .01) and loose/watery stools (OR = 1.84, P = .04). Hedonic eating was associated with abdominal pain/discomfort with stool frequency change (OR = 2.4, P = .02), >3 bowel movements per day (OR = 1.93, P = .048), bloating (OR = 2.49, P = .01), abdominal pain after meals >1 per month (OR = 4.24, P < .01), and nausea >1 per week (OR = 4.51, P < .01).

CONCLUSION

Alterations in hunger, satiation, postprandial satiety, and hedonic eating are associated with GIS in patients with obesity.

Orthorexia nervosa is a concern in gastroenterology: A scoping review

There is concern that use of restrictive therapeutic diets, such as those used in disorders of the gut-brain interaction (DGBI), may increase disordered eating. In this issue of Neurogastroenterology and Motility, Burton Murray et al. and Peters et al. both demonstrate a high prevalence of disordered eating in patients with gastrointestinal conditions, particularly those with DGBI. Given these findings, it is likely that orthorexia is common in this patient group, although this was not directly examined in these studies. Orthorexia nervosa is described as an obsessive and unsafe focus on eating foods perceived as healthy. This mini-review therefore focuses on orthorexia by conducting a scoping review, as per the PRISMA extension for scoping reviews, aimed to assess the prevalence of orthorexia, and associations between orthorexia and restrictive eating practices. While a wide range of orthorexia prevalence has been reported (0%-97%) across the 57 studies included, no studies assessed prevalence specifically in gastrointestinal conditions. Four of eight studies describing diseases associated with specific dietary patterns suggested that participants who followed a diet for "digestive issues" or "food intolerances" were at higher orthorexia risk. These results suggest that dietary modifications may be a factor contributing to orthorexia. Additionally, we provide a commentary on the clinical implications of the findings for gastrointestinal conditions including a clinical flow chart. Clinicians should consider if a restrictive diet is appropriate for individuals with DGBI and include screening for disordered eating prior to implementation of dietary modifications. Future prospective studies should evaluate orthorexia within this patient group.

Effect of high altitude on human postprandial 13 C-octanoate metabolism, intermediary metabolites, gastrointestinal peptides, and visceral perception

OBJECTIVE

At high altitude (HA), acute mountain sickness (AMS) is accompanied by neurologic and upper gastrointestinal symptoms (UGS). The primary aim of this study was to test the hypothesis that delayed gastric emptying (GE), assessed by ¹³ C-octanoate breath testing (OBT), causes UGS in AMS. The secondary aim was to assess post-gastric mechanisms of OBT, which could confound results under these conditions, by determination of intermediary metabolites, gastrointestinal peptides, and basal metabolic rate.

METHODS

A prospective trial was performed in 25 healthy participants (15 male) at 4559 m (HA) and at 490 m (Zurich). GE was assessed by OBT (428 kcal solid meal) and UGS by visual analogue scales (VAS). Blood sampling of metabolites (glucose, free fatty acids (FFA), triglycerides (TG), beta-hydroxyl butyrate (BHB), L-lactate) and gastrointestinal peptides (insulin, amylin, PYY, etc.) was performed as well as blood gas analysis and spirometry.

STATISTICAL ANALYSIS

variance analyses, bivariate correlation, and multilinear regression analysis.

RESULTS

After 24 h under hypoxic conditions at HA, participants developed AMS (p < 0.001). ¹³ CO₂ exhalation kinetics increased (p < 0.05) resulting in reduced estimates of gastric half-emptying times (p < 0.01). However, median resting respiratory quotients and plasma profiles of TG indicated that augmented beta-oxidation was the main predictor of accelerated ¹³ CO₂ -generation under these conditions.

CONCLUSION

Quantification of ¹³ C-octanoate oxidation by a breath test is sensitive to variation in metabolic (liver) function under hypoxic conditions. ¹³ C-breath testing using short-chain fatty acids is not reliable for measurement of gastric function at HA and should be considered critically in other severe hypoxic conditions, like sepsis or chronic lung disease.

General versus hunger/satiety-specific interoceptive sensibility in predicting disordered eating

Dysfunctional interoceptive processing of hunger and satiety cues is particularly relevant to disordered eating behaviors. However, researchers often rely on general measures of interoceptive sensibility (IS¹; self-reported experience of internal bodily cues) which conflate interoceptive processes across biological systems (e.g., gastric, cardiac) when assessing the role of interoception in disordered eating. Participants (N = 213; 50% female, age M = 20.77 years) were recruited from a large southeastern university for this online study and completed the Intuitive Eating Scale-2 (hunger/satiety-specific), the Multidimensional Assessment of Interoceptive Awareness-2 (general), and the Eating Disorder Inventory Interoceptive Awareness Subscale (general) as measures of IS. The Eating Pathology Symptoms Inventory was used to assess disordered eating attitudes and behaviors. Controlling for sex and body mass index, hunger/satiety-specific IS was associated with binge eating, purging, and cognitive restraint over and above general IS measures and emerged as the dominant predictor of each. Hunger/satiety-specific IS did not predict restricting behavior. Dysfunctional processing of hunger and satiety cues may be a particularly important risk factor to target in screenings and interventions for disordered eating. Findings highlight the importance of careful selection of IS measures in research and targeting hunger/satiety-specific IS in clinical interventions for disordered eating.

Gastrointestinal Interoception in Eating Disorders: Charting a New Path

PURPOSE OF REVIEW

Abnormal interoception has been consistently observed across eating disorders despite limited inclusion in diagnostic conceptualization. Using the alimentary tract as well as recent developments in interoceptive neuroscience and predictive processing as a guide, the current review summarizes evidence of gastrointestinal interoceptive dysfunction in eating disorders.

RECENT FINDINGS

Eating is a complex process that begins well before and ends well after food consumption. Abnormal prediction and prediction-error signals may occur at any stage, resulting in aberrant gastrointestinal interoception and dysregulated gut sensations in eating disorders. Several interoceptive technologies have recently become available that can be paired with computational modeling and clinical interventions to yield new insights into eating disorder pathophysiology. Illuminating the neurobiology of gastrointestinal interoception in eating disorders requires a new generation of studies combining experimental probes of gut physiology with computational modeling. The application of such techniques within clinical trials frameworks may yield new tools and treatments with transdiagnostic relevance.

Pooled Analysis of Gastric Emptying in Patients With Obesity: Implications for Oral Absorption Projection

PURPOSE

Gastric emptying time is one of limiting factors that determines the pharmacokinetic properties of drugs administered by mouth. Despite the high prevalence of obesity worldwide, modifications in gastric emptying time have not been systematically addressed in this set of patients. The current analysis aims to quantitatively address obesity-related changes in gastric emptying time of solids, semisolids, and liquids compared with lean individuals, highlighting the relevant pharmacokinetic implications of oral drug absorption in patients with obesity.

METHODS

We searched the Cochrane Library, PubMed, Web of Science, and Embase for all relevant articles published until November 1, 2020. Differences in gastrointestinal variables in relation to gastric emptying between obese and lean individuals were quantified by weighted mean difference (WMD) and ratio of means (RoM). Robustness of the analyses was evaluated by subgroup analysis and publication bias test.

FINDINGS

A total of 17 studies with 906 participants were included. The gastric half-emptying time of solids (WMD, -10.4 minutes; P = 0.001; RoM, 0.90; P = 0.01) and liquids (WMD, -6.14 minutes; P < 0.001; RoM, 0.83, P = 0.03) was significantly shorter in individuals with obesity compared with lean individuals. These findings were confirmed by the subgroup analyses and publication bias tests.

IMPLICATIONS

Our pooled analysis systemically quantifies the differences in gastric half-emptying time between individuals with obesity and lean individuals, facilitating better understanding and prediction of drug absorption in individuals with obesity through physiologically based pharmacokinetic approaches. Obesity is associated with a faster transit of both solids and liquids through the stomach.

Gut inference: A computational modelling approach

Neurocomputational theories have hypothesized that Bayesian inference underlies interoception, which has become a topic of recent experimental work in heartbeat perception. To extend this approach beyond cardiac interoception, we describe the application of a Bayesian computational model to a recently developed gastrointestinal interoception task completed by 40 healthy individuals undergoing simultaneous electroencephalogram (EEG) and peripheral physiological recording. We first present results that support the validity of this modelling approach. Second, we provide a test of, and confirmatory evidence supporting, the neural process theory associated with a particular Bayesian framework (active inference) that predicts specific relationships between computational parameters and event-related potentials in EEG. We also offer some exploratory evidence suggesting that computational parameters may influence the regulation of peripheral physiological states. We conclude that this computational approach offers promise as a tool for studying individual differences in gastrointestinal interoception.

Effect of obesity on gastrointestinal transit, pressure and pH using a wireless motility capsule

BACKGROUND

Despite the increasing prevalence and medical burden of obesity, the understanding of gastrointestinal physiology in obesity is scarce, which hampers drug development.

AIM

To investigate the effect of obesity and food intake on gastrointestinal transit, pressure and pH.

MATERIAL AND METHODS

An exploratory cross-sectional study using a wireless motility capsule (SmartPill©) was performed in 11 participants with obesity and 11 age- and gender-matched participants with normal weight (group) in fasted and fed state (visit). During the first visit, the capsule was ingested after an overnight fast. During a second visit, the capsule was ingested after a nutritional drink to simulate fed state. Linear mixed models were constructed to compare segmental gastrointestinal transit, pressure and pH between groups (obesity or control) and within every group (fasted or fed).

RESULTS

Food intake slowed gastric emptying in both groups (both P < 0.0001), though food-induced gastric contractility was higher in participants with obesity compared to controls (P = 0.02). In the small intestine, a higher contractility (P = 0.001), shorter transit (P = 0.04) and lower median pH (P = 0.002) was observed in participants with obesity compared to controls. No differences were observed for colonic measurements.

CONCLUSION

Obesity has a profound impact on gastrointestinal physiology, which should be taken into account for drug development.

Disorders of the brain-gut interaction and eating disorders

BACKGROUND

Eating disorders (ED) involve both the nervous system and the gastrointestinal tract. A similar double involvement is also found in disorders of the brain-gut interaction (DGBI) and symptoms are sometimes similar.

AIM

To find out where there is an association and a cause-effect relationship, we looked for the comorbidity of DGBI and ED.

METHODS

A systematic review was undertaken. A literature search was performed. Inclusion criteria for the articles retained for analysis were: Observational cohort population-based or hospital-based and case-control studies, examining the relationship between DGBI and ED. Exclusion criteria were: Studies written in other languages than English, abstracts, conference presentations, letters to the Editor and editorials. Selected papers by two independent investigators were critically evaluated and included in this review.

RESULTS

We found 29 articles analyzing the relation between DGBI and ED comprising 13 articles on gastroparesis, 5 articles on functional dyspepsia, 7 articles about functional constipation and 4 articles on irritable bowel syndrome.

CONCLUSION

There is no evidence for a cause-effect relationship between DGBI and ED. Their common symptomatology requires correct identification and a tailored therapy of each disorder.

Irritable bowel syndrome and functional dyspepsia in patients with eating disorders - a systematic review

OBJECTIVES

The prevalence of eating disorders is rising worldwide. The low body weight in anorexia nervosa as well as the increase in body mass index due to binge eating disorder are contributing to a strikingly high morbidity and mortality. In a similar pattern, the prevalence and burden of the disease of functional gastrointestinal disorders such as functional dyspepsia and irritable bowel syndrome is increasing. As gastrointestinal complaints are commonly reported by patients with eating disorders, the question arose whether there is a relationship between eating disorders and functional gastrointestinal disorders.

METHODS

To address the need to better understand the interplay between eating disorders and functional gastrointestinal disorders as well as factors that might influence this connection, the data bases Medline, Web of Science and Embase were systematically searched.

RESULTS

After removal of duplicates the search yielded 388 studies which were screened manually. As a result, 36 publications were selected for inclusion in this systematic review.

CONCLUSION

The occurrence of functional gastrointestinal disorders like irritable bowel syndrome and functional dyspepsia in patients with eating disorders is considerably high and often associated with psychological, hormonal and functional alterations. In the future, further research addressing the underlying mechanisms accounting for this relationship is required.

Evaluating disorders of gut-brain interaction in eating disorders

OBJECTIVE

Eating disorders commonly co-occur with gastrointestinal problems. This case-control study aimed to (a) document the prevalence of disorders of gut-brain interaction (DGBI) in eating disorders, (b) examine the specific impact of disordered eating behaviors on the risk of DGBI, and (c) explore the impact of current eating disorder psychopathology on DGBI.

METHOD

We included 765 cases with eating disorders and 1,240 controls. DGBI were assessed via the ROME III questionnaire. Prevalences of DGBI were calculated across eating disorder diagnoses (anorexia nervosa, bulimia nervosa, and multiple eating disorders) and in controls. The association between disordered eating behaviors and DGBI was examined using logistic regression models. Lastly, we compared the total number of DGBI in individuals with high versus low current eating disorder symptoms.

RESULTS

A large majority (88.2-95.5%) of individuals with eating disorders reported at least one DGBI and 34.8-48.7% reported three or more DGBI. Of the DGBI categories, functional bowel disorders were the most commonly endorsed category, and of the individual DGBI, irritable bowel syndrome was the most frequently reported (43.9-58.8%). All investigated disordered eating behaviors showed a positive association with most DGBI categories. Finally, individuals reporting high current eating disorder symptoms reported higher mean number of DGBI (3.03-3.34) than those with low current symptoms (1.60-1.84).

DISCUSSION

The directionality and mechanisms underlying the nature of the relationship between gastrointestinal and eating disorder symptoms is worthy of further study and clinicians should adopt an integrated approach by attending to both gastrointestinal and eating disorder symptoms in their patients.

The intersect of gastrointestinal symptoms and malnutrition associated with anorexia nervosa and avoidant/restrictive food intake disorder: Functional or pathophysiologic?-A systematic review

OBJECTIVE

Although multiple pathophysiologic changes develop within the gastrointestinal (GI) system in the setting of malnutrition, the etiology of the reported multitude of symptoms in those with anorexia nervosa and avoidant restrictive intake disorder, as well as their contribution toward disordered eating, remain poorly understood. This systematic review seeks to better understand how these physiologic changes of malnutrition of the esophagus, stomach, intestines, and pancreas contribute toward the reported GI symptoms, as well as better understand how celiac disease, inflammatory bowel disease, pelvic floor dysfunction, and Ehlers-Danlos syndrome contribute toward disordered eating.

METHODS

Studies of any design exploring the pathogenesis of complications and treatment strategies were included. Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were used to structure and complete the review.

RESULTS

A total of 146 articles were used for the review. The majority of studies were observational or case reports/case series.

DISCUSSION

Pathophysiologic changes of the esophagus, stomach, and intestines develop with malnutrition, although these changes do not consistently correlate with expressed GI symptoms in patients with restrictive eating disorders. Celiac disease and inflammatory bowel disease also contribute to disordered eating through the associated somatic GI complaints, while pelvic floor dysfunction and Ehlers-Danlos syndrome contribute through both somatic symptoms and functional symptoms. Indeed, functional GI symptoms remain problematic during the course of treatment, and further research is required to better understand the extent to which these symptoms are functional in nature and remit or remain as treatment ensues.

Gastrointestinal symptoms following treatment for anorexia nervosa: A systematic literature review

OBJECTIVE

Gastrointestinal (GI) disturbances are a frequent and burdensome experience for patients with anorexia nervosa (AN). How GI symptoms respond to current interventions is not well characterized, yet is critical to facilitate treatment success, and to inform the development of new treatments for AN. Therefore, the aim of this systematic review was to identify which treatments are effective in improving GI symptoms in patients with AN.

METHOD

A systematic search for studies of AN treatments measuring GI symptoms pre- and post-treatment was conducted in May 2020 (PROSPERO ID: CRD42020181328). After removal of duplicates, title and abstracts of 3,370 studies were screened. Methodological quality was assessed using National Institute of Health Quality Assessment Tool.

RESULTS

Following full-text screening, 13 studies (12 observational studies and 1 randomized double-blind placebo-controlled trial) with 401 participants met eligibility criteria and were included. All observational studies included a component of nutritional rehabilitation, with half (n = 6) involving concurrent psychological treatment. The randomized controlled trial reported a drug therapy. Eleven studies reported an improvement in all (n = 6) or at least one (n = 5) patient-reported GI symptom following treatment. Two studies reported no change. Methodological quality was fair or poor across all studies.

DISCUSSION

This is the first systematic review to synthesize available evidence on the trajectory of patient-reported GI symptoms from commencement to end of treatment for AN. The results suggest that most studies showed improvement in one or more GI symptom in response to current treatments. Future therapeutic approaches should consider GI symptoms within their design for optimal treatment adherence and outcomes.

Internal states and interoception along a spectrum of eating disorder symptomology

OBJECTIVE

Recent studies on atypical interoceptive capabilities have focused on clinical populations, including anorexia nervosa[1,2]. The present exploratory study aims to characterize the influence of disordered eating symptomology on interoceptive capabilities in college students, a population for which dangerous dieting behaviors may emerge.

METHOD

Ninety-nine participants were randomized to consume a blinded high calorie or low calorie midday shake. Participants reported frequency of eating disorder cognitions and behaviors; indicated changes in satiety, happiness, and energy pre- and post-consumption; and guessed the calories in their shake. Outcomes (perceived satiety, changes in mood, and caloric guess) were regressed on eating disorder symptoms scores, the high/low calorie shake condition, and the interaction between these predictors.

RESULTS

Those randomized to receive the high calorie shake reported feeling fuller, but only when endorsing lower levels of eating concern. Those randomized to the high calorie shake reported greater post-meal happiness, but only at greater levels of eating concerns. Lastly, those with lower levels of eating restraint reported an expected positive association between level of fullness and calorie guess, but those with higher levels of eating restraint did not exhibit any relationship between perceived fullness and calorie guess.

DISCUSSION

Results of this exploratory suggest that irregular eating habits (e.g., not eating a sufficient amount for lunch) may have direct consequences on interoceptive capabilities. Further, these capacities may be impacted by individual differences in eating concern and restraint. Preliminary findings suggest that impairment in deciphering visceral signals may be associated with the degree of eating disorder symptomology; such impairment may occur at lower levels of symptomatology than normative data would indicate.

The Phantom Satiation Hypothesis of Bariatric Surgery

The excitation of vagal mechanoreceptors located in the stomach wall directly contributes to satiation. Thus, a loss of gastric innervation would normally be expected to result in abrogated satiation, hyperphagia, and unwanted weight gain. While Roux-en-Y-gastric bypass (RYGB) inevitably results in gastric denervation, paradoxically, bypassed subjects continue to experience satiation. Inspired by the literature in neurology on phantom limbs, I propose a new hypothesis in which damage to the stomach innervation during RYGB, including its vagal supply, leads to large-scale maladaptive changes in viscerosensory nerves and connected brain circuits. As a result, satiation may continue to arise, sometimes at exaggerated levels, even in subjects with a denervated or truncated stomach. The same maladaptive changes may also contribute to dysautonomia, unexplained pain, and new emotional responses to eating. I further revisit the metabolic benefits of bariatric surgery, with an emphasis on RYGB, in the light of this phantom satiation hypothesis.

Influence of Glutamine and Branched-Chain Amino Acids Supplementation during Refeeding in Activity-Based Anorectic Mice

Background: Optimizing the refeeding of patients with anorexia nervosa remains important to limit somatic complications of malnutrition, as well as to avoid disease relapses by targeting persistent mood and intestinal disorders. We aimed to evaluate the effects of glutamine (Gln) and branched-chain amino acids (BCAA) supplementation during refeeding in activity-based anorectic (ABA) mice. Method: Male C57Bl/6 mice were randomized in control and ABA groups. Once ABA-induced malnutrition was established, mice were progressively refed or not. Refed mice had free access to drinking water supplemented or not with 1% Gln or 2.5% BCAA for 10 days. Results: A progressive refeeding was associated with a partial restoration of body weight and lean mass, while a fat mass rebound was observed. In addition, refeeding restored glucose and leptin. Gln did not affect these parameters, while BCAA tended to increase body weight, fat mass, and glycaemia. In the colon, refeeding improved total protein synthesis and restored the LC3II/LC3I ratio, a marker of autophagy. Gln supplementation enhanced colonic protein synthesis, which was associated with an increased p-p70S6kinase/p70S6kinase ratio, whereas these effects were blunted by BCCA supplementation. Conclusions: In ABA mice, Gln and BCAA supplementations during a progressive refeeding fail to restore body weight and lean mass. However, Gln supplementation improves total colonic protein synthesis conversely to BCAA. Further studies are needed to decipher the underlying mechanisms involved in these opposite results.

Interoception and Its Role for Eating, Obesity, and Eating Disorders

Abstract. The importance of the sense of ourselves from within for understanding adaptive behavior and psychopathology has been increasingly recognized during the last decades. Interoception builds the foundation of our embodied self and dysfunctional interoception lies at the core of many psychosomatic disorders. Eating is fundamental for survival with consequences for health and well-being. It is deeply grounded in homoeostatic and allostatic psychophysiological needs and is driven by interoceptive signals of the body. This narrative review summarizes a selection of empirical findings and draws conclusions on the role of interoception in eating behavior, body weight, and eating disorders. Beyond disordered eating behavior, eating disorders are characterized by impairment of the sense of self, with dysfunctional interoception at its core. Predictive coding accounts are addressed to integrate conclusions and to underline the relevance of interventions to modify interoception.

Backstage of Eating Disorder-About the Biological Mechanisms behind the Symptoms of Anorexia Nervosa

Anorexia nervosa (AN) represents a disorder with the highest mortality rate among all psychiatric diseases, yet our understanding of its pathophysiological components continues to be fragmentary. This article reviews the current concepts regarding AN pathomechanisms that focus on the main biological aspects involving central and peripheral neurohormonal pathways, endocrine function, as well as the microbiome–gut–brain axis. It emerged from the unique complexity of constantly accumulating new discoveries, which hamper the ability to look at the disease in a more comprehensive way. The emphasis is placed on the mechanisms underlying the main symptoms and potential new directions that require further investigation in clinical settings.

Effects of hunger on mood and affect reactivity to monetary reward in women with obesity - A pilot study

Worldwide, nearly 3 million people die every year because of being overweight or obese. Although obesity is a metabolic disease, behavioral aspects are important in its etiology. Hunger changes the rewarding potential of food in normal-weight controls. In obesity, impairments related to reward processing are present, but it is not clear whether these are due to mental disorders more common among this population. Therefore, in this pilot study, we aimed at investigating whether fasting influence mood reactivity to reward in people with obesity. Women with obesity (n = 11, all mentally healthy) and normal weight controls (n = 17) were compared on a computerized monetary reward task (the wheel of fortune), using self-reports of mood and affect (e.g., PANAS and mood evaluation during the task) as dependent variables. This task was done in 2 satiety conditions, during fasting and after eating. Partially, in line with our expectation of a reduced affect and mood reactivity to monetary reward in participants with obesity accentuated by fasting, our results indicated a significant within-group difference across time (before and after the task), with monetary gains significantly improving positive affect in healthy controls (p>0.001), but not in individuals with obesity (p = 0.32). There were no significant between-group differences in positive affect before (p = 0.328) and after (p = 0.70) the task. In addition, women with obesity, compared to controls, reported more negative affect in general (p < 0.05) and less mood reactivity during the task in response to risky gains (p < 0.001) than healthy controls. The latter was independent of the level of satiety. These preliminary results suggest an impairment in mood reactivity to monetary reward in women with obesity which is not connected to the fasting state. Increasing the reinforcing potential of rewards other than food in obesity may be one target of intervention in order to verify if that could reduce overeating.

Which Symptoms, Complaints and Complications of the Gastrointestinal Tract Occur in Patients With Eating Disorders? A Systematic Review and Quantitative Analysis

BACKGROUND

Eating disorders (ED) such as anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED) are often accompanied by a variety of psychological and physical comorbidities. Gastrointestinal (GI) symptoms are a classical feature in most patients with ED. The heterogeneity of studies on this topic is high, making it difficult to have a clear overview. The aim of this systematic review is therefore to provide an overview of subjectively and objectively measured differences and changes in the GI tract in patients with EDs, along with the occurrence of GI complications.

METHODS

A systematic literature search was conducted in PubMed, Web of Science, and Google Scholar to find all relevant studies examining GI problems in AN, BN, and BED. Quantitative analyses were performed for objective GI physiology measures where applicable.

RESULTS

The review differentiated between ED types and also between studies that report GI outcomes of ED in (i) human studies with an ED diagnosis excluding case reports that provide an overview of GI problems in ED and (ii) case reports with an ED diagnosis describing rare GI complications in ED. GI symptoms and impaired gastric transit times were frequent features of EDs with specific differences found for the ED types. During the time course of treatment, GI symptoms changed and/or improved but not completely. GI complications extended the range of GI problems observed, including a variety of serious complications such as gastric dilatation.

CONCLUSIONS

Problems of the GI tract are frequent in patients with ED and it is likely that they complicate therapy, especially in patients with AN.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number: CRD42019100585.

The Role of Interoception in the Pathogenesis and Treatment of Anorexia Nervosa: A Narrative Review

Anorexia nervosa (AN) is a psychiatric illness characterized by extreme overvaluation of weight and disturbed eating. Despite having the highest mortality rate of any psychiatric illness, the etiology and neurobiology of AN are poorly understood. A growing body of research has begun to elucidate the role of reward processing, as well as cognitive and limbic networks, in the symptomology of AN. However, these advances have so far failed to contribute therapeutically, suggesting a new understanding may be necessary. A disturbance in the interoceptive system, involved in perceiving and interpreting the physiological condition of the body, has recently been proposed as a central mechanism of pathology in AN, through links to hunger and satiety, risk prediction errors, emotional awareness, and body dysmorphia. This review summarizes the existing literature in order to clarify possible underlying mechanisms and proposes a novel model of the neuro-circuitry of AN. Detailed neuroanatomical studies and new methods for studying interoception may allow further refinement of this model and the development of improved treatment.

Eating Disorders and Gastrointestinal Diseases

Eating disorders (ED) are frequently associated with a wide range of psychiatric or somatic comorbidities. The most relevant ED are anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorders (BED). Patients with ED exhibit both upper and lower gastrointestinal (GI) symptoms. Evidence of alterations throughout the GI tract in ED will be analyzed given the role of the GI tract in food intake and its regulation. It remains a matter of debate whether GI disorders are inherent manifestations of ED or the results of malnutrition occurring from ED. Moreover, recent clinical studies have highlighted the growing role of intestinal microbiota in the pathogenesis of ED, making it possible to hypothesize a modulation of intestinal microbiota as a co-adjuvant to standard therapy. The aim of this review is to analyze the link between ED and GI diseases and to present, where known, the potential key factors underlying these conditions. Conclusions: The presence of GI disorders should be investigated in patients with ED. Screening for ED should also be encouraged in individuals seeking treatment for unexplained GI complaints to better address therapeutic issues that surround these difficult medical conditions.

Eating Disorders and Gastrointestinal Diseases

Eating disorders (ED) are frequently associated with a wide range of psychiatric or somatic comorbidities. The most relevant ED are anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorders (BED). Patients with ED exhibit both upper and lower gastrointestinal (GI) symptoms. Evidence of alterations throughout the GI tract in ED will be analyzed given the role of the GI tract in food intake and its regulation. It remains a matter of debate whether GI disorders are inherent manifestations of ED or the results of malnutrition occurring from ED. Moreover, recent clinical studies have highlighted the growing role of intestinal microbiota in the pathogenesis of ED, making it possible to hypothesize a modulation of intestinal microbiota as a co-adjuvant to standard therapy. The aim of this review is to analyze the link between ED and GI diseases and to present, where known, the potential key factors underlying these conditions. Conclusions: The presence of GI disorders should be investigated in patients with ED. Screening for ED should also be encouraged in individuals seeking treatment for unexplained GI complaints to better address therapeutic issues that surround these difficult medical conditions.

Disrupted Oxytocin-Appetite Signaling in Females With Anorexia Nervosa

CONTEXT

In healthy females, oxytocin levels decrease postmeal, corresponding to increased satiety. The postprandial response of oxytocin in females with anorexia nervosa (AN)/atypical AN is unknown.

OBJECTIVES

To determine the pattern of postprandial serum oxytocin levels in females with AN/atypical AN, relationship with appetite, and effect of weight, eating behavior, and endogenous estrogen status.

DESIGN

Cross-sectional.

SETTING

Clinical research center.

PARTICIPANTS

67 women (36 with AN [<85% expected body weight (EBW)]; 31 with atypical AN [≥ 85% EBW)]), age 22.4 ± 0.9 (mean ± SEM) years, categorized by weight, restricting vs binge/purge behavior, and estrogen status.

INTERVENTIONS

Standardized mixed meal.

MAIN OUTCOME MEASUREMENTS

Blood sampling for oxytocin occurred fasting and 30, 60, and 120 minutes postmeal. Subjective appetite was assessed using visual analog scales.

RESULTS

In females with AN/atypical AN, oxytocin levels decreased from fasting to 60 (P = 0.002) and 120 (P = 0.005) minutes postmeal. The decrease in oxytocin from fasting to 120 minutes was greater in females with atypical AN than AN (P = 0.027) and did not differ by restricting vs binge/purge behavior or estrogen status. Controlling for caloric intake, the decrease in oxytocin was inversely related to the decrease in hunger postmeal in females with atypical AN (P = 0.04).

CONCLUSIONS

In females with AN/atypical AN, oxytocin levels decrease postmeal, as established in healthy females. Weight, but not restricting vs binge/purging nor endogenous estrogen status, affects postprandial oxytocin levels. The postprandial change in serum oxytocin levels is related to appetite in females with atypical AN only, suggesting a disconnect between oxytocin secretion and appetite in the undernourished state.

A preliminary naturalistic clinical case series study of the feasibility and impact of interoceptive exposure for eating disorders

Recent literature suggests that individuals with eating disorders demonstrate altered interoceptive processing, which may relate to the maintenance of symptoms and thus represent a salient treatment target. Adopting treatment techniques effective for other conditions characterized by disturbed interoceptive processes (e.g., anxiety disorders) could aid in improving the outcomes of psychological interventions for eating disorders. The current investigation was a naturalistic case series (N = 4) that examined adjunctive interoceptive exposure (IE) for eating disorders, with an emphasis on evaluating the feasibility, acceptability, and impact of this intervention on anxiety sensitivity, interoceptive deficits, and eating disorder symptoms. Results suggested that all individuals who received 4 consecutive sessions of traditional and eating-disorder-specific IE exercises demonstrated decreases in interoceptive deficits and subjective distress. Results for anxiety sensitivity and eating disorder symptoms were encouraging yet more mixed. Findings also generally suggested that the intervention was feasible and acceptable, yet between-session practice compliance varied considerably among participants. Overall, we describe how IE may be used to target interoceptive deficits in eating disorders and provide preliminary evidence of how this may be accomplished within naturalistic intensive outpatient settings.

Appetite Perceptions, Gastrointestinal Symptoms, Ghrelin, Peptide YY and State Anxiety Are Disturbed in Adolescent Females with Anorexia Nervosa and Only Partially Restored with Short-Term Refeeding

Factors underlying disturbed appetite perception in anorexia nervosa (AN) are poorly characterized. We examined in patients with AN whether fasting and postprandial appetite perceptions, gastrointestinal (GI) hormones, GI symptoms and state anxiety (i) differed from healthy controls (HCs) and (ii) were modified by two weeks of refeeding. 22 female adolescent inpatients with restricting AN, studied on hospital admission once medically stable (Wk0), and after one (Wk1) and two (Wk2) weeks of high-calorie refeeding, were compared with 17 age-matched HCs. After a 4 h fast, appetite perceptions, GI symptoms, state anxiety, and plasma acyl-ghrelin, cholecystokinin (CCK), peptide tyrosine tyrosine (PYY) and pancreatic polypeptide (PP) concentrations were assessed at baseline and in response to a mixed-nutrient test-meal (479 kcal). Compared with HCs, in patients with AN at Wk0, baseline ghrelin, PYY, fullness, bloating and anxiety were higher, and hunger less, and in response to the meal, ghrelin, bloating and anxiety were greater, and hunger less (all p < 0.05). After two weeks of refeeding, there was no change in baseline or postprandial ghrelin or bloating, or postprandial anxiety, but baseline PYY, fullness and anxiety decreased, and baseline and postprandial hunger increased (p < 0.05). We conclude that in AN, refeeding for 2 weeks was associated with improvements in PYY, appetite and baseline anxiety, while increased ghrelin, bloating and postprandial anxiety persisted.

Gastric motor and sensory function in health assessed by magnetic resonance imaging: Establishment of reference intervals for the Nottingham test meal in healthy subjects

BACKGROUND

Current investigations of gastric emptying rarely identify the cause of symptoms or provide a definitive diagnosis in patients with dyspepsia. This study assessed gastric function by magnetic resonance imaging (MRI) using the modular "Nottingham test meal" (NTM) in healthy volunteers (HVs).

METHODS

The NTM comprises (a) 400 mL liquid nutrient (0.75 kcal/mL) labeled with Gadolinium-DOTA and (b) an optional solid component (12 agar-beads [0 kcal]). Filling sensations were documented. MRI measurements of gastric volume, emptying, contraction wave frequency, and secretion were obtained using validated methods.

KEY RESULTS

Gastric function was measured in a population of 73 HVs stratified for age and sex. NTM induced moderate satiety and fullness. Labeled fluid was observed in the small bowel in all subjects after meal ingestion ("early-phase" GE). Secretion was rapid such that postprandial gastric content volume was often greater than meal volume (GCV0 > 400 mL), and there was increasing dilution of the meal during the study (P < 0.001). Gastric half-time was median 66-minutes (95% reference interval 35 to 161-minutes ["late-phase" GE]). The number of intact agar beads in the stomach was 7/12 (58%) at 60-minutes and 1/12 (8%) at 120-minutes. Age, bodyweight and sex had measurable effects on gastric function; however, these were small compared to inter-individual variation for most metrics.

CONCLUSIONS AND INFERENCES

Reference intervals are presented for MRI measurements of gastric function assessed for the mixed liquid/solid NTM. Studies in patients will determine which metrics are of clinical value and also whether the reference intervals presented here offer optimal diagnostic sensitivity and specificity.

Effects of starvation and short-term refeeding on gastric emptying and postprandial blood glucose regulation in adolescent girls with anorexia nervosa

Postprandial glucose is reduced in malnourished patients with anorexia nervosa (AN), but the mechanisms and duration for this remain unclear. We examined blood glucose, gastric emptying, and glucoregulatory hormone changes in malnourished patients with AN and during 2 wk of acute refeeding compared with healthy controls (HCs). Twenty-two female adolescents with AN and 17 age-matched female HCs were assessed after a 4-h fast. Patients were commenced on a refeeding protocol of 2,400 kcal/day. Gastric emptying (¹³C-octanoate breath test), glucose absorption (3-O-methylglucose), blood glucose, plasma glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), insulin, C-peptide, and glucagon responses to a mixed-nutrient test meal were measured on admission and 1 and 2 wk after refeeding. HCs were assessed once. On admission, patients had slower gastric emptying, lower postprandial glucose and insulin, and higher glucagon and GLP-1 than HCs ( P < 0.05). In patients with AN, the rise in glucose (0-30 min) correlated with gastric emptying ( P < 0.05). With refeeding, postprandial glucose and 3-O-methylglucose were higher, gastric emptying faster, and baseline insulin and C-peptide less ( P < 0.05), compared with admission. After 2 wk of refeeding, postprandial glucose remained lower, and glucagon and GLP-1 higher, in patients with AN than HCs ( P < 0.05) without differences in gastric emptying, baseline glucagon, or postprandial insulin. Delayed gastric emptying may underlie reduced postprandial glucose in starved patients with AN; however, postprandial glucose and glucoregulatory hormone changes persist after 2 wk of refeeding despite improved gastric emptying. Future research should explore whether reduced postprandial glucose in AN is related to medical risk by examining associated symptoms alongside continuous glucose monitoring during refeeding.

Critical gaps in the medical knowledge base of eating disorders

Eating disorders are unique in that they inherently have much medical comorbidity both as a part of restricting-type eating disorders and those characterized by purging behaviors. Over the last three decades, remarkable progress has been made in the understanding and treatment of the medical complications of eating disorders. Yet, unfortunately, there is much research that is sorely needed to bridge the gap between current medical knowledge and more effective and evidence-based medical treatment knowledge. These gaps exist in many different clinical areas including cardiology, electrolytes, gastrointestinal and bone disease. In this paper, we discuss some of the knowledge gap areas, which if bridged would help develop more effective medical intervention for this population of patients.

Delayed gastric emptying and altered antrum protein metabolism during activity-based anorexia

BACKGROUND

Anorexia nervosa, a restrictive eating disorder, is often associated with gastrointestinal disorders, particularly a delayed gastric emptying. However, the mechanisms remained poorly documented. Thus, we aimed to evaluate gastric emptying and antrum protein metabolism in the Activity-Based Anorexia model (ABA).

METHODS

Females C57Bl/6 mice were randomized into 3 groups: Control, ABA, and Limited Food Access (LFA). Food access has been progressively limited from 6 h/day at day 6 to 3 h/day at day 9 and until day 17. ABA mice had free access to an activity wheel. Gastric emptying was assessed. On gastric extracts, a proteomic analysis was performed, as well as an evaluation of protein synthesis and protein oxidation.

KEY RESULTS

Both LFA and ABA mice exhibited a delayed gastric emptying compared with Controls (P < .05). Proteomic approach revealed 15 proteins that were differentially expressed. Among these proteins, we identified 2 clusters of interest contributing to (i) the organization of muscle fiber with ACTA2, VCL, KRT19, KRT8, and DES proteins and (ii) "heat shock proteins" with STIP1, HSPD1, and HSPA8 proteins. ABA mice specifically exhibited an increased rate of gastric oxidized proteins.

CONCLUSIONS AND INFERENCES

Delayed gastric emptying observed in anorectic conditions appears to be secondary to malnutrition. However, an oxidative stress is specifically present in the stomach of ABA mice. Its role remains to be further studied.

Differential Diagnoses of Food-Related Gastrointestinal Symptoms in Patients with Anorexia Nervosa and Bulimia Nervosa: A Review of Literature

OBJECTIVES

The present review investigates the prevalence and medical causes of food-related gastrointestinal symptoms in eating disorder (ED) patients and recommends a diagnostic algorithm based on the current literature.

METHODS

A literature search was conducted, which included publications from January 2000 until January 2017 Results: Over 90% of ED patients suffer from food-related symptoms. There is no evidence for a higher prevalence of immunological or structural gastrointestinal disorders in ED patients compared to the healthy population. Most food-related symptoms in ED patients are likely to be functional.

CONCLUSIONS

Diagnostic work-up of food-related symptoms in ED patients needs to be based on clinical history. Only if timing and quality of symptoms point towards a disorder independent from the ED is a comprehensive diagnostic work-up necessary.

Clinical assessment of gastric emptying and sensory function utilizing gamma scintigraphy: Establishment of reference intervals for the liquid and solid components of the Nottingham test meal in healthy subjects

BACKGROUND

Current investigations of stomach function are based on small test meals that do not reliably induce symptoms and analysis techniques that rarely detect clinically relevant dysfunction. This study presents the reference intervals of the modular "Nottingham test meal" (NTM) for assessment of gastric function by gamma scintigraphy (GSc) in a representative population of healthy volunteers (HVs) stratified for age and sex.

METHODS

The NTM comprises 400 mL liquid nutrient (0.75 kcal/mL) and an optional solid component (12 solid agar-beads (0 kcal). Filling and dyspeptic sensations were documented by 100 mm visual analogue scale (VAS). Gamma scintigraphy parameters that describe early and late phase Gastric emptying (GE) were calculated from validated models.

KEY RESULTS

Gastric emptying (GE) of the liquid component was measured in 73 HVs (male 34; aged 45±20). The NTM produced normal postprandial fullness (VAS ≥30 in 41/74 subjects). Dyspeptic symptoms were rare (VAS ≥30 in 2/74 subjects). Gastric emptying half-time with the Liquid- and Solid-component -NTM was median 44 (95% reference interval 28-78) minutes and 162 (144-193) minutes, respectively. Gastric accommodation was assessed by the ratio of the liquid-NTM retained in the proximal:total stomach and by Early phase emptying assessed by gastric volume after completing the meal (GCV0). No consistent effect of anthropometric measures on GE parameters was present.

CONCLUSIONS AND INFERENCES

Reference intervals are presented for GSc measurements of gastric motor and sensory function assessed by the NTM. Studies involving patients are required to determine whether the reference interval range offers optimal diagnostic sensitivity and specificity.

Getting to the heart of the matter: Does aberrant interoceptive processing contribute towards emotional eating?

According to estimates from Public Health England, by 2034 70% of adults are expected to be overweight or obese, therefore understanding the underpinning aetiology is a priority. Eating in response to negative affect contributes towards obesity, however, little is known about the underlying mechanisms. Evidence that visceral afferent signals contribute towards the experience of emotion is accumulating rapidly, with the emergence of new influential models of ‘active inference’. No longer viewed as a ‘bottom up’ process, new interoceptive facets based on ‘top down’ predictions have been proposed, although at present it is unclear which aspects of interoception contribute to aberrant eating behaviour and obesity. Study one examined the link between eating behaviour, body mass index and the novel interoceptive indices; interoceptive metacognitive awareness (IAw) and interoceptive prediction error (IPE), as well as the traditional measures; interoceptive accuracy (IAc) and interoceptive sensibility (IS). The dissociation between these interoceptive indices was confirmed. Emotional eaters were characterised by a heightened interoceptive signal but reduced meta-cognitive awareness of their interoceptive abilities. In addition, emotional eating correlated with IPE; effects that could not be accounted for by differences in anxiety and depression. Study two confirmed the positive association between interoceptive accuracy and emotional eating using a novel unbiased heartbeat discrimination task based on the method of constant stimuli. Results reveal new and important mechanistic insights into the processes that may underlie problematic affect regulation in overweight populations.