Samantha Scholtz

Obese patients after gastric bypass surgery have lower brain-hedonic responses to food than after gastric banding

Objectives Roux-en-Y gastric bypass (RYGB) has greater efficacy for weight loss in obese patients than gastric banding (BAND) surgery. We hypothesise that this may result from different effects on food hedonics via physiological changes secondary to distinct gut anatomy manipulations. Design We used functional MRI, eating behaviour and hormonal phenotyping to compare body mass index (BMI)-matched unoperated controls and patients after RYGB and BAND surgery for obesity. Results Obese patients after RYGB had lower brain-hedonic responses to food than patients after BAND surgery. RYGB patients had lower activation than BAND patients in brain reward systems, particularly to high-calorie foods, including the orbitofrontal cortex, amygdala, caudate nucleus, nucleus accumbens and hippocampus. This was associated with lower palatability and appeal of high-calorie foods and healthier eating behaviour, including less fat intake, in RYGB compared with BAND patients and/or BMI-matched unoperated controls. These differences were not explicable by differences in hunger or psychological traits between the surgical groups, but anorexigenic plasma gut hormones (GLP-1 and PYY), plasma bile acids and symptoms of dumping syndrome were increased in RYGB patients. Conclusions The identification of these differences in food hedonic responses as a result of altered gut anatomy/physiology provides a novel explanation for the more favourable long-term weight loss seen after RYGB than after BAND surgery, highlighting the importance of the gut–brain axis in the control of reward-based eating behaviour.

Ghrelin mimics fasting to enhance human hedonic, orbitofrontal cortex, and hippocampal responses to food

BACKGROUND Ghrelin, which is a stomach-derived hormone, increases with fasting and energy restriction and may influence eating behaviors through brain hedonic reward-cognitive systems. Therefore, changes in plasma ghrelin might mediate counter-regulatory responses to a negative energy balance through changes in food hedonics. OBJECTIVE We investigated whether ghrelin administration (exogenous hyperghrelinemia) mimics effects of fasting (endogenous hyperghrelinemia) on the hedonic response and activation of brain-reward systems to food. DESIGN In a crossover design, 22 healthy, nonobese adults (17 men) underwent a functional magnetic resonance imaging (fMRI) food-picture evaluation task after a 16-h overnight fast (Fasted-Saline) or after eating breakfast 95 min before scanning (730 kcal, 14% protein, 31% fat, and 55% carbohydrate) and receiving a saline (Fed-Saline) or acyl ghrelin (Fed-Ghrelin) subcutaneous injection before scanning. One male subject was excluded from the fMRI analysis because of excess head motion, which left 21 subjects with brain-activation data. RESULTS Compared with the Fed-Saline visit, both ghrelin administration to fed subjects (Fed-Ghrelin) and fasting (Fasted-Saline) significantly increased the appeal of high-energy foods and associated orbitofrontal cortex activation. Both fasting and ghrelin administration also increased hippocampus activation to high-energy- and low-energy-food pictures. These similar effects of endogenous and exogenous hyperghrelinemia were not explicable by consistent changes in glucose, insulin, peptide YY, and glucagon-like peptide-1. Neither ghrelin administration nor fasting had any significant effect on nucleus accumbens, caudate, anterior insula, or amygdala activation during the food-evaluation task or on auditory, motor, or visual cortex activation during a control task. CONCLUSIONS Ghrelin administration and fasting have similar acute stimulatory effects on hedonic responses and the activation of corticolimbic reward-cognitive systems during food evaluations. Similar effects of recurrent or chronic hyperghrelinemia on an anticipatory food reward may contribute to the negative impact of skipping breakfast on dietary habits and body weight and the long-term failure of energy restriction for weight loss.

Link Between Increased Satiety Gut Hormones and Reduced Food Reward After Gastric Bypass Surgery for Obesity

Context: Roux-en-Y gastric bypass (RYGB) surgery is an effective long-term intervention for weight loss maintenance, reducing appetite, and also food reward, via unclear mechanisms. Objective: To investigate the role of elevated satiety gut hormones after RYGB, we examined food hedonic-reward responses after their acute post-prandial suppression. Design: These were randomized, placebo-controlled, double-blind, crossover experimental medicine studies. Patients: Two groups, more than 5 months after RYGB for obesity (n = 7–11), compared with nonobese controls (n = 10), or patients after gastric banding (BAND) surgery (n = 9) participated in the studies. Intervention: Studies were performed after acute administration of the somatostatin analog octreotide or saline. In one study, patients after RYGB, and nonobese controls, performed a behavioral progressive ratio task for chocolate sweets. In another study, patients after RYGB, and controls after BAND surgery, performed a functional magnetic resonance imaging food picture evaluation task. Main Outcome Measures: Octreotide increased both appetitive food reward (breakpoint) in the progressive ratio task (n = 9), and food appeal (n = 9) and reward system blood oxygen level-dependent signal (n = 7) in the functional magnetic resonance imaging task, in the RYGB group, but not in the control groups. Results: Octreotide suppressed postprandial plasma peptide YY, glucagon-like peptide-1, and fibroblast growth factor-19 after RYGB. The reduction in plasma peptide YY with octreotide positively correlated with the increase in brain reward system blood oxygen level-dependent signal in RYGB/BAND subjects, with a similar trend for glucagon-like peptide-1. Conclusions: Enhanced satiety gut hormone responses after RYGB may be a causative mechanism by which anatomical alterations of the gut in obesity surgery modify behavioral and brain reward responses to food.

Eating disorders in older women: does late onset anorexia nervosa exist?

OBJECTIVE The objective of this study is to determine whether eating disorders can present for the first time in older people. METHOD This is a descriptive study of patients above the age of 50 years who have presented to a national eating disorder center within the last 10 years. RESULTS Thirty-two patients were identified; data were available for 26 of these patients and 11 agreed for further interview and questionnaire completion. There were no cases where the eating disorder had its onset late in life. Of the 11 interviewed, six participants retained a diagnosis of anorexia nervosa, four had Eating Disorder Not Otherwise Specified and only one was recovered. Comorbid depression was universal in those still suffering with an eating disorder diagnosis, and their level of social functioning was impaired. DISCUSSION Anorexia nervosa is a chronic and enduring mental illness that, although rare, can be found in older people. In our sample, we found no evidence of late-onset disorders; all described cases were lifelong.

Psychological characteristics, eating behavior, and quality of life assessment of obese patients undergoing weight loss interventions

Background and Aims: Bariatric surgery is the most effective treatment for obesity. However, not all patients have similar weight loss following surgery and many researchers have attributed this to different pre-operative psychological, eating behavior, or quality-of-life factors. The aim of this study was to determine whether there are any differences in these factors between patients electing to have bariatric surgery compared to less invasive non-surgical weight loss treatments, between patients choosing a particular bariatric surgery procedure, and to identify whether these factors predict weight loss after bariatric surgery. Material and Methods: This was a prospective study of 90 patients undergoing gastric bypass, vertical sleeve gastrectomy, or adjustable gastric banding and 36 patients undergoing pharmacotherapy or lifestyle interventions. All patients completed seven multi-factorial psychological, eating behavior, and quality-of-life questionnaires prior to choosing their weight loss treatment. Questionnaire scores, baseline body mass index, and percent weight loss at 1 year after surgical interventions were recorded. Results and Conclusions: Surgical patients were younger, had a higher body mass index, and obesity had a higher impact on their quality of life than on non-surgical patients, but they did not differ in the majority of eating behavior and psychological parameters studied. Patients opting for adjustable gastric banding surgery were more anxious, depressed, and had more problems with energy levels than those choosing vertical sleeve gastrectomy, and more work problems compared to those undergoing gastric bypass. Weight loss after bariatric surgery was predicted by pre-operative scores of dietary restraint, disinhibition, and pre-surgery energy levels. The results of this study generate a number of hypotheses that can be explored in future studies and accelerate the development of personalized weight loss treatments.

The role of bariatric surgery in the management of female fertility

This Review has been produced by the Scientific Advisory Committee of the Royal College of Obstetricians and Gynaecologists and was first published in March 2010 at http://www.rcog.org.uk/womens-health/clinical-guidance/role-bariatric-surgery-management-female-fertility. The article is reproduced in Human Fertility with permission following an agreement between the RCOG and the BFS to collaborate in the production and dissemination of policy documents in Reproductive Medicine.

Changes in Reward after Gastric Bypass: the Advantages and Disadvantages

Gastric bypass surgery is an effective long-term weight loss intervention. Key to its success appears a putative shift in food preference away from high-energy-density foods associated with a reduced appetitive drive and loss of neural reactivity in the reward system of the brain towards food. Post-prandial exaggerated satiety gut hormone responses have been implicated as mediators. Whilst the positive impact of bariatric surgery on both physical and psychological outcomes for many patients is clearly evident, a subset of patients appear to be detrimentally affected by this loss of reward from food and by a lack of alternative strategies for regulating affect after surgery. Mindfulness training has emerged as a potential tool in reducing the need for immediate reward that underpins much of eating behaviour. Further research is needed to help identify patients who may be more vulnerable after gastric bypass and which forms of support may be most beneficial.

Change in Sexual Dysfunction Following Bariatric Surgery

Obesity is associated with multiple comorbidities and psychosocial burdens, but often sexual dysfunction (SD) is overlooked. Bariatric surgery is the most effective treatment for morbid obesity, and its role in reversing SD is reviewed. A literature search of MEDLINE, PubMed Central, and Cochrane databases was conducted. Fifty-six articles were identified and 32 selected for inclusion. SD was measured via hormonal studies, questionnaires, and a combination of both (n = 14 males SD studies, n = 13 female SD studies, 5 = both sexes). There is an exponential rise in patients reporting post-surgical improvements in SD in both genders. The emerging use of quality of life indices to measure sexual function as part of a more global enjoyment of life may be a helpful adjunct to existing hormonal and sex-specific measures.

Quantified-Self for Obesity: Physical Activity Behaviour Sensing to Improve Health Outcomes.

Physical activity levels in bariatric patients have not been well documented, despite their importance in maintaining weight loss following surgery. This study investigated the feasibility of tracking physical activity using a smartphone app with minimal user interaction. Thus far, we have obtained good quality data from 255 patients at various points in their weight loss journey. Preliminary analyses indicate little change in physical activity levels following surgery with pre-surgery patients reaching an average of 16 minutes per day and post-surgery patients achieving a daily average of 21 minutes. Further analyses using machine-learning techniques will be conducted to determine whether physical activity is a critical factor in distinguishing between successful and unsuccessful weight loss outcomes and in the resolution of comorbid conditions in patients with similar clinical profiles.

Effects of 8 weeks oligofructose supplementation on appetite and body weight in overweight and obese adults

Supplementing the diet with fermentable carbohydrate (FC) has been suggested to reduce appetite and body weight. Recent findings have demonstrated that inulin-type fructans reduce food intake, body weight and fat mass in rodents. However, the effects in humans are inconclusive. This study investigated the effects of FC [oligofructose (OFS)] on appetite profiles, satiety hormone concentration, colonic fermentation, energy intake and body weight following 8 weeks supplementation in overweight and obese adults. 22 healthy subjects, male (n 6), female (n 16), mean age 30 (SD 8) years with mean BMI 31.1 (SD 3.4) kg/m completed a randomised, double-blind, parallel study comprised of a 2 week run-in period followed by 30 g fibre/day supplementation of either OFS (n 12) or placebo (cellulose +maltodextrin) (n 10) for 6 weeks. On day 0 (baseline) and day 56 (post-supplementation) subjects were served a standardised breakfast and lunch. Throughout a 420 min postprandial period blood samples were taken to determine peptide YY (PYY) concentrations and visual analogue scales were used to assess subjective appetite feelings. Breath hydrogen was also recorded as a marker of colonic fermentation. Following 420 min participants were served an ad libitum meal to measure energy intake. Dietary supplementation with OFS significantly decreased hunger (P = 0.016), motivation to eat (P = 0.027) and significantly increased breath hydrogen (P = 0.017) on day 56 compared with cellulose treatment. However, subjective fullness (P = 0.187), energy intake (P = 0.344) and PYY (P = 0.145) were not affected by OFS treatment. Supplementing the diet with OFS had no effect on body weight compared with cellulose (P = 0.461)