Morning and afternoon appetite and gut hormone responses to meal and stress challenges in obese individuals with and without binge eating disorder.

BACKGROUND: Eating late in the day is common, and stress can induce eating. Little is understood about how time of day and stress interact to affect appetite and thereby body weight. These may be particularly important influences in binge eaters, who tend to binge in the evening, and in response to stress. METHOD: Obese participants with (n=16) and without (n=16) binge eating disorder (BED) participated in two identical test protocols beginning either in the morning or the afternoon (AM condition/PM condition), each following an 8 h fast. For each protocol, they first received a standardized liquid meal (0900/1600 hours), then a stress test (Socially Evaluated Cold Pressor Test, 1110/1810 hours), and then a multi-item ad libitum buffet meal (1140/1840 hours) while rating appetite and stress and having blood drawn for hormone measures. RESULTS: Appetite at baseline was greater in the PM than in the AM condition (higher hunger, lower fullness). Following the liquid meal, area under the curve (AUC) values for hunger and ghrelin were greater and AUC values for peptide YY lower in the PM than in the AM condition. Only those with BED showed lower fullness AUC in the PM condition, as well as a pattern of higher initial PM and lower initial AM ghrelin. Following the stress test, cortisol and ghrelin increased in both the AM and PM conditions, but higher ghrelin AUC and lower cortisol AUC were observed in the PM condition. Again, only participants with BED showed lower fullness AUC in the PM condition. Buffet meal intake was similar across groups and conditions but those with BED reported greater loss of control and binge resemblance than those without. CONCLUSIONS: Afternoon/evening may be a high-risk period for overeating, particularly when paired with stress exposure, and for those with binge eating.

Ghrelin.

BACKGROUND: The gastrointestinal peptide hormone ghrelin was discovered in 1999 as the endogenous ligand of the growth hormone secretagogue receptor. Increasing evidence supports more complicated and nuanced roles for the hormone, which go beyond the regulation of systemic energy metabolism. SCOPE OF REVIEW: In this review, we discuss the diverse biological functions of ghrelin, the regulation of its secretion, and address questions that still remain 15 years after its discovery. MAJOR CONCLUSIONS: In recent years, ghrelin has been found to have a plethora of central and peripheral actions in distinct areas including learning and memory, gut motility and gastric acid secretion, sleep/wake rhythm, reward seeking behavior, taste sensation and glucose metabolism.

Electroretinographic detection of human brain dopamine response to oral food stimulation.

OBJECTIVE: The activity of dopamine-dependent retinal signaling can be assessed using electroretinography. Response of this system to oral food stimulation might provide accessible insight into the brain dopamine response to oral stimuli as retinal dopamine concentration is dependent upon mid brain dopamine concentration was postulated. DESIGN AND METHODS: Nine individuals had cone ERG (b wave) response to oral food stimulation and oral methylphenidate (MPH) administration measured on separate days, and completed self reported eating behavior questionnaires. RESULTS: Significant and similar increases in b wave response to both stimuli (P = 0.012 and P = 0.042, MPH and food, respectively) and significant correlations of the food stimulated b wave amplitude with binge eating related behavior as measured by the Gormally Binge Eating Scale (r = 0.68, P = 0.044) and self-reported trait hunger as measured by the Stunkard and Messick Three Factor Eating Questionnaire (r = 0.67, P = 0.048) were found. CONCLUSION: The significant increase in food stimulated dopamine dependent b wave amplitude and correlation with methylphenidate stimulated b wave amplitude suggest that ERG may offer a relatively inexpensive and accessible methodology for potentially assess dopaminergic responses to food and other externally applied stimuli that have been implicated in the pathogenesis of a number of human diseases.

Cortisol and ghrelin concentrations following a cold pressor stress test in overweight individuals with and without night eating.

OBJECTIVE: To explore appetite-related hormones following stress in overweight individuals, and their relationship with night eating (NE) status. METHOD: We measured plasma cortisol and ghrelin concentrations, and recorded ratings of stress and hunger in response to a physiological laboratory stressor (cold pressor test, CPT), in overweight women with (n=11; NE) and without (n=17; non-NE) NE. RESULTS: Following the CPT, cortisol (P<0.001) and ghrelin (P<0.05) levels increased, as did stress and hunger ratings (all P<0.001), across all subjects (NE and non-NE). NE exhibited higher baseline cortisol (P<0.05) levels than non-NE. NE also had greater cortisol area under the curve (AUC) than non-NE (P=0.019), but not when controlling for baseline cortisol levels. Ghrelin baseline and AUC did not differ between groups. NE showed higher AUC stress (P<0.05), even when controlling for baseline stress. DISCUSSION: Overweight individuals showed increased cortisol, ghrelin, stress and hunger following a laboratory stressor, and there was some evidence for greater increases in cortisol and subjective stress among NE. The greater AUC cortisol level in NE was due to higher baseline levels, but the group difference in stress was in direct response to the stressor. Our results support a role for cortisol and stress in NE.

Body adiposity index (BAI) correlates with BMI and body fat pre- and post-bariatric surgery but is not an adequate substitute for BMI in severely obese women.

OBJECTIVE: Body Adiposity Index (BAI), a new surrogate measure of body fat (hip circumference/[height 1.5-18]), has been proposed as a more accurate alternative to BMI. We compared BAI with BMI and their correlations with measures of body fat, waist circumference (WC), and indirect indices of fat pre- and post-Roux-en-Y gastric bypass (RYGB). METHODS: Sixteen clinically severe obese (CSO) non-diabetic women (age = 33.9± 7.9 SD; BMI = 46.5±9.5 kg/m(2)) were assessed pre-surgery, and at 2 (n=9) and 5 mo (n=8) post-surgery. Body fat percentage (% fat) was estimated with bioimpedance analysis (BIA), air displacement plethysmography (ADP), and dual-energy x-ray absorptiometry (DXA). WC, an indicator of central fat, and both plasma leptin (ng/ml) and insulin (mU/l) concentrations were measured as indirect body fat indices. Pre- and post-surgery values were analyzed with Pearson correlations and linear regressions. RESULTS: BAI and BMI correlated significantly with each other pre-surgery and at each time point post surgery. BAI and BMI also correlated significantly with % fat from BIA and ADP; however, only BMI correlated significantly with % fat from DXA pre- and post-RYGB. BMI was the single best predictor of WC and leptin at 2 and 5 mo post-surgery and had significant longitudinal changes correlating with % fat from BIA and DXA as well as with leptin. DISCUSSION: Both BAI and BMI were good surrogates of % fat as estimated from BIA and ADP, but only BMI was a good surrogate of % fat from DXA in CSO women. Thus, BAI may not be a better alternative to BMI.

Relation between changes in neural responsivity and reductions in desire to eat high-calorie foods following gastric bypass surgery.

Reductions in reward-related (e.g. striatal) neural activation have been noted following obesity surgery. It has been speculated that these postoperative neural changes may be related to documented postoperative changes in food preferences; however, this relation has not been previously established. In this study, functional magnetic resonance imaging and rating scales were used to assess neural responsivity, desire to eat (i.e. wanting), and liking for high- and low-calorie food cues in 14 females one month pre- and one month post-Roux-en-Y gastric bypass (RYGB) surgery. Pre- to post-RYGB changes in all variables were assessed, and postoperative changes in neural responsivity were regressed on postoperative changes in desire to eat and liking of foods. Results revealed significant postoperative reductions in mesolimbic (e.g. striatal) neural responsivity, desire to eat (wanting), and liking for high- relative to low-calorie food cues. Postoperative reductions in mesolimbic responsivity were associated with postoperative reductions in wanting, but not liking, for high- versus low-calorie foods. Interestingly, reductions in food wanting were also related to reductions in inhibitory (e.g. dorsolateral prefrontal cortex) activation following RYGB. Results are consistent with the hypothesized delineation between wanting and liking, supporting the notion that wanting, but not liking, is processed through the dopaminergic reward pathway. Concurrent reductions in both reward-related and inhibitory activation-predicted reductions in desire to eat might suggest that less dietary inhibition was elicited to resist potential overconsumption as the anticipated reward value of high-calorie foods decreased following RYGB.

Neuroimaging and obesity: current knowledge and future directions.

Neuroimaging is becoming increasingly common in obesity research as investigators try to understand the neurological underpinnings of appetite and body weight in humans. Positron emission tomography (PET), functional magnetic resonance imaging (fMRI) and magnetic resonance imaging (MRI) studies examining responses to food intake and food cues, dopamine function and brain volume in lean vs. obese individuals are now beginning to coalesce in identifying irregularities in a range of regions implicated in reward (e.g. striatum, orbitofrontal cortex, insula), emotion and memory (e.g. amygdala, hippocampus), homeostatic regulation of intake (e.g. hypothalamus), sensory and motor processing (e.g. insula, precentral gyrus), and cognitive control and attention (e.g. prefrontal cortex, cingulate). Studies of weight change in children and adolescents, and those at high genetic risk for obesity, promise to illuminate causal processes. Studies examining specific eating behaviours (e.g. external eating, emotional eating, dietary restraint) are teaching us about the distinct neural networks that drive components of appetite, and contribute to the phenotype of body weight. Finally, innovative investigations of appetite-related hormones, including studies of abnormalities (e.g. leptin deficiency) and interventions (e.g. leptin replacement, bariatric surgery), are shedding light on the interactive relationship between gut and brain. The dynamic distributed vulnerability model of eating behaviour in obesity that we propose has scientific and practical implications.

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.

Changes in neurohormonal gut peptides following bariatric surgery.

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

Neuroimaging, gut peptides and obesity: novel studies of the neurobiology of appetite.

Two major biological players in the regulation of body weight are the gut and the brain. Peptides released from the gut convey information about energy needs to areas of the brain involved in homeostatic control of food intake. There is emerging evidence that human food intake is also under the control of cortical and subcortical areas related to reward and cognition. The extent to which gut hormones influence these brain areas is not fully understood. Novel methods combining the study of neural activity and hormonal signalling promise to advance our understanding of gut-brain interactions. Here, we review a growing number of animal and human studies using neuroimaging methods (functional magnetic resonance imaging, positron emission tomography) to measure brain activation in relation to nutrient loads and infusion of gut peptides. Implications for current and future pharmacological treatments for obesity are discussed.

Comparison of eating disorders and body image disturbances between Eastern and Western countries.

Factors associated with the development of eating disorders in countries with non-Western cultures have not been adequately investigated in relation to Westernized countries. We therefore studied 243 girls [age =16.5+/-1.2 (SD)], recruited from schools in India, Tibet, the US and France. They completed the Figure Rating Scale (FRS), the Eating Attitudes Test (EAT), and the Beck Depression Inventory (BDI). The Tibetan group had a lower body mass index (BMI) than the other groups (p<0.0001), which did not differ from each other. All groups differed significantly on socio-economic status (SES), with those living in India having the highest (p<0.0001). Prior to controlling for age, SES, and BMI, there were no significant differences on any psychological measure between the individual countries, or when collapsed by East vs. West. However, after controlling for the same covariates, the Tibetan group selected a significantly larger current (p<0.0001) and ideal body size (p=0.03), compared to all the other countries, and had more body image discrepancy than the American group (p=0.04). After controlling only for BMI, the girls from the East had a larger current and ideal, but no difference on body image discrepancy. Body image discrepancy scores were best predicted by EAT scores and BMI, accounting for 35% of the variance (p<0.0001). EAT scores themselves were best predicted by mother's education, BDI, body image discrepancy, and drug and tobacco use, accounting for 33% of the variance (p<0.0001). Unlike some other studies, we did not observe greater body image discrepancy and eating pathology in Western cultures, whether or not controlling for age, SES, and BMI. There were no differences in eating and depression pathology between those in the US, France, or India. Indeed, the Tibetans, after controlling for their low BMI and SES, had the greatest body image discrepancy.

Night eating status and influence on body weight, body image, hunger, and cortisol pre- and post- Roux-en-Y Gastric Bypass (RYGB) surgery.

Night Eating Syndrome is a common disorder in severely obese individuals and may be associated with hypothalamic pituitary adrenal (HPA) axis dysregulation. This study compared night eaters (NE) and comparably obese controls (C) pre- and post-Roux-en- Y Gastric Bypass surgery at 2 and 5 months, following an overnight fast on hormonal measures associated with HPA axis and related appetite and psychological measures. There were 24 (10 NE, 14 C) clinically severely obese participants (body mass index =47.0+/-8.4 SD). At pre-surgery baseline, afternoon fasting hunger ratings differed significantly and were lower for NE than for C (p=0.01). Eight of the participants (4 NE, 4C) returned for all 3 study visits. At 5 months post-surgery, NE and C did not differ in weight loss, reductions in waist circumference, insulin levels, and insulin resistance (homeostasis model assessment). However, NE as compared to C, did not improve in self ratings of body image (p<0.05), and had significant increases in fasting afternoon cortisol levels 5 months after surgery (p=0.01).

Comparison of psychological characteristics of binging and nonbinging obese, adult, female outpatients.

OBJECTIVE: This study compared levels of depression, anxiety and self-esteem in binging and nonbinging obese, adult females in a hospital weight-loss program. METHOD: Participants (n=43; mean age=43.5 yrs) completed the Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI) and Coopersmith Self-Esteem Inventory (CSEI) upon entering the program (Week 0). A subgroup (n=15) completed the same inventories on Week 4 and Week 8. RESULTS: Binge eaters had significantly higher levels of depression (p<0.002) and lower levels of self-esteem (p<0.001) on Week 0. For the subgroup that remained in the program through Week 8, significantly higher depression levels (p<0.01) and anxiety levels (p<0.05) persisted for the binge eaters. DISCUSSION: Results indicate that obese binge eaters have more psychological distress than nonbingers, and that these differences tend to persist even during weight loss.

Night eating syndrome is associated with depression, low self-esteem, reduced daytime hunger, and less weight loss in obese outpatients.

OBJECTIVE: The objective of this study was to assess the relationship between the night eating syndrome (NES), measures of depression and self-esteem, test meal intake, and weight loss in obese participants. RESEARCH METHODS AND PROCEDURES: The study included 76 overweight (body mass index = 36.7 +/- 6.5 SD) outpatients (53 women and 23 men; aged 43.5 +/- 9.5 years) entering a weight loss program. They completed a Night Eating Questionnaire, the Zung Depression Inventory, and the Rosenberg Self-Esteem SCALE: Based on criteria by Stunkard et al. (Stunkard A, Berkowitz R, Wadden T, Tanrikut C, Reiss E, Young L. Binge eating disorder and the night eating syndrome. Int J Obes Relat Metab DISORD: 1996;20:1-6), participants had NES if they reported: (1) skipping breakfast > or =4 d/wk, interpreted as morning anorexia; (2) consuming more than 50% of total daily calories after 7 PM; and (3) difficulty falling asleep or staying asleep > or =4 d/wk. Eleven (14%) participants met the criteria for NES. After an 8-hour fast, all participants ingested a nutritionally complete liquid meal through a straw from a large opaque cooler until extremely full. They also completed ratings of hunger and fullness before and after this meal. RESULTS: Night eaters had higher depression (p = 0.04), lower self-esteem (p = 0.003), and less hunger (p = 0.005), and a trend for more fullness (p = 0.06) before the daytime test meal than the others. However, there were no significant differences in test-meal intake between groups. Nevertheless, test-meal intake was greater later in the day only for the night eaters (p = 0.01). Over a 1-month period, the night eaters lost less weight (4.4 +/- 3.2 kg) than the others (7.3 +/- 3.2 kg; p = 0.04), after controlling for body mass index. DISCUSSION: NES is a syndrome with distinct psychopathology and increased food intake later in the day, both of which may contribute to poorer weight loss outcome. NES criteria need to be better quantified and NES deserves consideration as a diagnostic eating disorder.

Test meal intake in obese binge eaters in relation to mood and gender.

OBJECTIVE: We assessed test meal intake in men and women with and without binge eating disorder (BED) in relation to mood score (Zung scale). METHODS: Eighty-five overweight subjects (24 males and 61 females) participated; 30 subjects with BED and 55 without BED. Following an 8-hr fast, subjects consumed a liquid test meal until extremely full. RESULTS: BED subjects consumed significantly more (p =.009) of the test meal (1,032 g +/- 429) than the non-binge eaters (737 g +/- 399). The men ingested more than the women (p =.002). BED subjects also had higher depression scores (p =.01), without differing by gender. However, depression scores were unrelated to test meal intakes (r = -.01). DISCUSSION: The larger meal intakes of the BED group may be due to the larger stomach capacity previously found in both bulimics and obese subjects. The findings also support the premise that BED, listed in the DSM-IV appendix for further study, is found in a distinct subgroup of overweight individuals.

Gastric capacity in normal, obese, and bulimic women.

One function of the stomach is as a reservoir for food; hence, the stomach's capacity may limit the amount of food ingested. A stomach with a large capacity has been associated with bigger test meals. We compared the stomach capacity of three groups of women: normal (n=10), obese (n=11), and bulimic (n=10). Following an overnight fast, gastric capacity was estimated by filling a gastric balloon with water at 100 ml/min, with pauses for measuring intragastric pressure. One estimate was based on the maximum volume the subject could tolerate as indicated by a maximal rating of abdominal discomfort. Another estimate was based on the volume required to produce a given rise of intragastric pressure, 5 cm H(2)O. A third related measure was based on a maximal rating of fullness. Based on these estimates, the gastric capacity of the bulimics was the largest, with the obese subjects intermediate. We then separated the obese subjects according to whether they reported binge eating (n=6) or not (n=5). The gastric capacity of the binge-eating subset was similar to the bulimics, and the nonbinge-eating subset was similar to the normals. Thus, gastric capacity appears more related to binge eating behavior than to body weight.

Work-shift period and weight change.

The present study was done to determine whether weight gain was more prevalent in workers on late shifts than in those on day shifts. A questionnaire about changes in weight, food intake, exercise, and sleep since starting the job on the current shift was given to day-shift and late-shift (evening and night) hospital workers. Data were analyzed for 85 subjects, 36 of whom worked during the day shift and 49 the late shift. The late-shift group reported a mean weight gain of 4.3 kg, which was greater than the mean weight gain of 0.9 kg for the day-shift group (P = 0.02). There were, however, no significant differences in current body mass index (26.7 +/- 5.4 SD) between groups. There was a trend for late-shift workers to report eating more since beginning the later shift (P = 0.06). When combined with those reporting exercising less (P = NS), this trend became significant (P = 0.04). Late-shift workers reported eating fewer meals (1.9 +/- 0.9 SD) than the day-shift workers (2.5 +/- 0.9; P = 0.002). In addition, late-shift workers reported eating the last daily meal later (mean = 22:27, or 10:27 PM) than day-shift workers (17:52 or 5:52 PM; P < 0.00005). Late-shift workers also reported more naps (P = 0.01) and longer naps (P = 0.05) during the work week than did day-shift workers. The reported changes in eating, exercise, and sleep may contribute to the increased weight gain of late-shift workers.