Hunger Sensations Research Articles

Dietary Changes Albertan Women Make During Pregnancy: Thematic Analysis of Self-reported Changes and Reasons.

To explore dietary changes Albertan women make during pregnancy, reasons they make changes, and alignment with prenatal nutrition recommendations. Women up to 6 months postpartum were recruited in public health centres and Primary Care Networks. Qualitative data were collected through a self-administered survey including 2 open-ended questions that asked about changes made to food/beverage intake during pregnancy and why these changes were made. A majority (n = 577) of the 737 women completing the survey described changes they made to their food/beverage intake during pregnancy and 193 respondents provided reasons for these changes. Increased intake of fruits/vegetables, meat, milk, and their alternatives (n = 600); limiting or avoidance of foods/beverages known to be harmful during pregnancy (n = 445); and increased food/fluid intake or meal/snack frequency (n = 405) were commonly reported dietary changes. Motivations relating to health and to control physiological changes/manage health conditions were the most frequent reasons provided. Women make diverse dietary changes and have various motivations for food choices during pregnancy. A majority make dietary changes to support a healthy pregnancy. However, the motivation to control discomforts and respond to hunger and thirst sensations reflect a stronger influencer on women's choices than is currently addressed in prenatal nutrition messages.

Effectiveness, Compliance, and Acceptability of Preoperative Weight Loss with a Liquid Very Low-Calorie Diet Before Bariatric Surgery in Real Practice.

A preoperative very low-calorie diet (VLCD) is a common method to reduce weight before bariatric surgery. However, patient compliance and acceptability are not always known. The aim of this study is to evaluate the effectiveness, compliance, and acceptability of our regimen in a metropolitan academic quaternary care center. Patients with a BMI < 50kg/m2 and a BMI ≥ 50kg/m2 were instructed to be on a liquid VLCD for 1week and 2weeks, respectively. The primary outcome was the amount of weight loss. Secondary outcomes were patient compliance and acceptability of either regimen using a questionnaire for hunger, satisfaction, desire, and deviation for solids. The study included 128 patients. Ninety-four patients were in the BMI < 50kg/m2 group, and 34 patients were in the BMI ≥ 50kg/m2 group. The BMI ≥ 50kg/m2 group had a greater percentage of total weight loss (mean ± SD) than that of the BMI < 50kg/m2 group without statistical differences (4.4 ± 1.3% vs. 3.8 ± 1.6%, p = 0.072). There were no statistical differences between the groups in terms of hunger, satisfaction with a liquid diet, or satisfaction of eating over drinking. However, hunger sensation (median [IQR]) tended to be higher in the BMI < 50kg/m2 group than that in the BMI ≥ 50kg/m2 group (2 [2] vs. 2 [2, 3]; p = 0.06). There was no statistical difference in the percentage of patient compliance between the groups (75.5% [n = 71] vs. 61.8% [n = 21], p = 0.18). Preoperative liquid VLCD provided a modest amount of weight loss and showed a high rate of patient compliance and acceptability.

Abundance of gut Prevotella at baseline and metabolic response to barley prebiotics

PurposeWe previously showed that short-term intervention with barley kernel bread (BKB) improved glucose tolerance. However, glucose tolerance was not improved in a subset of individuals (non-responders) who were characterized by a low Prevotella/Bacteroides ratio. The purpose of the present study was to investigate if the baseline Prevotella/Bacteroides ratio can be used to stratify metabolic responders and non-responders to barley dietary fiber (DF).MethodsFecal samples were collected from 99 healthy humans with BMI < 28 kg/m2 between 50 and 70 years old. The abundance of fecal Prevotella and Bacteroides was quantified with 16S rRNA quantitative PCR. 33 subjects were grouped in three groups: subjects with highest Prevotella/Bacteroides ratios, “HP”, n = 12; subjects with lowest Prevotella/Bacteroides ratios, “LP”, n = 13; and subjects with high abundance of both measured bacteria, HPB, n = 8. A 3-day randomized crossover intervention with BKB and white wheat bread (control) was performed. Cardiometabolic test variables were analyzed the next day following a standardized breakfast.ResultsThe BKB intervention lowered the blood glucose responses to the breakfast independently of Prevotella/Bacteroides ratios (P < 0.01). However, independently of intervention, the HP group displayed an overall lower insulin response and lower IL-6 concentrations compared with the LP group (P < 0.05). Furthermore, the groups HP and HPB showed lower hunger sensations compared to the LP group (P < 0.05).ConclusionsHere we show that the abundance of gut Prevotella and Bacteroides at baseline did not stratify metabolic responders and non-responders to barley DF intervention. However, our results indicate the importance of gut microbiota in host metabolic regulation, further suggesting that higher Prevotella/Bacteroides ratio may be favorable.ClinicalTrials.gov IDNCT02427555

Altered Ghrelin Secretion Pattern and Sense of Hunger by Providing Low and High Density Breakfast in Obese Female Adolescents

Introduction: Ghrelin has been recognized to have a major influence on energy balance. Hence, the discovery of various regulatory factors that control ghrelin secretion may have major implications for the development of drugs and diet control. This study aims to analyze differences in ghrelin secretion pattern and prevention of hunger in the provision of breakfast in low-calorie breakfast, low energy density and high energy density in obese female adolescents.Methods: Subjects were female students aged 18-22 years with a BMI=25 kg/m², receiving low-calorie breakfast with low (n=8) and high energy density (n=8). Before the breakfast, subjects fasted for 12 hours and were subjected to plasma ghrelin level and hunger measurement using visual analog scale (VAS). Breakfast was done at 08.00, divided into three parts and each was taken for 5 minutes. Measurement of plasma ghrelin was carried out again post prandial (PP) at 2 hours and 4 hours. VAS filling was done 1 hour PP, 2 hours PP, 3 hours PP, and 4 hours PP.Result: There were differences in plasma ghrelin level, but not significant. VAS 1 analysis of hunger (p=0.040) at 4 hours PP and VAS 3 of satiety (p=0.025) was significantly different at 3 hours PP. Conclusion: Food density did not affect the plasma ghrelin levels. Low density foods are more effective to prevent hunger in 4 hours PP and increases satiety in 3 hours PP.

Influence of FTO rs9939609 polymorphism on appetite, ghrelin, leptin, IL6, TNFα levels, and food intake of women with morbid obesity.

BackgroundThe fat mass and obesity-related (FTO) gene has a strong relationship with obesity, extreme obesity and inflammatory state, and may also be associated with food intake regulation.ObjectiveThe aim of the present study was to evaluate the influence of the rs9939609 single-nucleotide polymorphism of the FTO gene on appetite, ghrelin, leptin, interleukin 6 (IL6), tumor necrosis factor α (TNFα) levels and food intake of morbidly obese women.Materials and methodsThe study comprised 70 women, aged between 20 and 48 years, from Rio de Janeiro, Brazil. The participants were selected according to the body mass index between 40 and 60 kg/m2. Anthropometric and biochemical data were measured during fasting. Hormones and inflammatory data were measured before and after the participants ate an isocaloric meal. Dietary records were calculated and analyzed using a nutritional assessment program. Visual analog scales were used for behaviors of the sensations of appetite and food preferences. The FTO rs9939609 variant was genotyped using real-time polymerase chain reaction.ResultsParticipants with the AA genotype had lower values of ghrelin and IL6 and higher values of leptin than those with TT and TA in the postprandial period. Comparing the plasma concentrations of ghrelin, insulin, IL6 and TNFα intragenotypes, it was observed that those with TT had decreased leptin and increased IL6 at the postprandial period. Subjects with TA showed increased postprandial IL6, and those with AA had decreased postprandial ghrelin. There was no difference in TNFα intra- and intergenotypes. The postprandial sensations of hunger were lower in AA than those with TT. There were differences between genotypes regarding ingested grams of protein by weight, cholesterol, B3, B5, B6 and B12 vitamins, and selenium potassium and sodium minerals.ConclusionThese findings suggest that genetics may exert an influence on physiologic factors and might alter eating behavior.

Tu1588 - Empty Stomach and Bothersome Hunger Sensation in Patients with Dyspepsia: A New Look at Forgotten Symptoms

Tu1588 - Empty Stomach and Bothersome Hunger Sensation in Patients with Dyspepsia: A New Look at Forgotten Symptoms

The pre-operation of the cesarean of the patients with the load of carbohydrate effect on the insulin resistance and the blood glucose level of the newborn

Objective To evaluate the comfort satisfaction and the insulin resistance of patients with cesarean section and the effects of the postoperative blood sugar on the newborns during the operation. Methods Forty patients who were got elective C-section were selected and divided randomly into two groups(n=20): oral carbohydrate group(CHO group), oral placebo group(P group). Both groups used epidural anesthesia, and a routine preoperative fasting 300 ml carbohydrate drinks(it contains 14.1 g of carbohydrates per 100 ml of drink) was administrated orally 2 h before anesthesia in oral CHO group. Patients in oral placebo group were given an equal amount distilled water instead of carbohydrate. The levels of blood glucose, plasma insulin and glucagons were tested after 2 h and after fetus delivery. According to levels of blood glucose and insulin, homeostasis model assessment(HOME) was applied to calculate the index of insulin resistance(HOMA-IR) and insulin sensitivity index(HOMA-ISI). After fetus delivery, neonates blood glucose was tested immediately. Meanwhile, the subjective comfort satisfaction of the two groups patients were also tested. Results After fetus delivery, blood glucose levels of two groups were significantly elevated than the levels of 2 h after loading(P<0.05). But there is no difference of blood glucose levels between two groups. Compare with levels of 2 h after loading, patients in P group had higher insulin levels, elevated HOMA-IR levels and lower HOME-ISI levels than levels of patients in CHO group (P<0.05). Patients in P group had higher glucagon levels that patients in CHO group. Patients in CHO group have less sense of hunger. Patients of two groups have no difference on sense of vomiting. The neonates blood glucose levels in the CHO group was higher than those in P group(P<0.05). Apgar scores of newborns in two groups are not different. Conclusions C-section preoperative oral intake of carbohydrate can safely reduce the insulin resistance and relieve the feelings of thirst, and help to raise blood glucose levels in newborns. Key words: Csection; Carbohydrate; Insulin resistance; Newborn; Blood glucose

The Gut Flora-Centric Theory Based on the New Medical Hypothesis of “Hunger Sensation Comes from Gut Flora”: A New Model for Understanding the Etiology of Chronic Diseases in Human Beings

The Gut Flora-Centric Theory Based on the New Medical Hypothesis of “Hunger Sensation Comes from Gut Flora”: A New Model for Understanding the Etiology of Chronic Diseases in Human Beings

The Gut Flora-Centric Theory Based on the New Medical Hypothesis of “Hunger Sensation Comes from Gut Flora”: A New Model for Understanding the Etiology of Chronic Diseases in Human Beings

The Gut Flora-Centric Theory Based on the New Medical Hypothesis of “Hunger Sensation Comes from Gut Flora”: A New Model for Understanding the Etiology of Chronic Diseases in Human Beings

Surgical Treatment Of Obesity

Obesity is associated with numerous comorbidities and shortens life expectancy. Currently, over one third of adults in the United States are obese, making management of obesity a significant public health concern. Given the modest benefits of behavior change alone, weight loss surgery has become a popular tool in the treatment of obesity. Numerous studies have documented the benefits of weight loss surgery in promoting weight loss and resolution of comorbidities. The hormonal and physiologic changes that are induced by some weight loss procedures are not yet fully elucidated, but it is thought that changes in hunger sensation and metabolism drive the observed effects. This review contains 4 figures, 2 videos, 3 tables and 60 references Key words: bypass, obesity, sleeve gastrectomy, surgery, weight loss

Subjective satiety and plasma PYY concentration after wholemeal pasta

Dietary fiber and whole grain foods may contribute to the regulation of appetite; however, evidence has produced inconclusive findings. The objective was to evaluate the effects of an experimental wholemeal pasta on appetite ratings, plasma concentrations of gastrointestinal hormones involved in appetite control, and postprandial glucose/insulin responses in healthy adults. Fourteen healthy adults (7M/7F), mean age 30±2 yrs (mean±SEM), participated in a randomized, controlled, crossover trial. Participants consumed on two different days, at one week interval, 117g of wholemeal pasta or 100g of refined wheat pasta (control pasta), similar in energy and macronutrient composition except for fiber amount, which was higher in wholemeal pasta (11 vs 3 g). Appetite ratings, glucose/insulin/lipid and gastrointestinal hormone responses were measured at fasting and for 4-h after the ingestion of the pasta tests, after which self-reported energy intake for 8-h was evaluated. After the wholemeal pasta, the desire to eat and the sensation of hunger were lower (-16%, p=0.04 and -23%, p=0.004, respectively) and satiety was higher (+13%; p=0.08) compared with the control pasta; no effect on self-reported energy intake at subsequent meal was observed. After wholemeal pasta, glucose, triglyceride increased and GLP-1 responses were not different compared to control pasta but insulin response at 30 min (p<0.05) and ghrelin at 60 min (p=0.03) were lower and PYY levels higher (AUC=+44%, p=0.001). The appetite rating changes correlated with PYY plasma levels (p<0.03). In conclusion, consumption of whole grain instead of refined wheat pasta contributed to appetite control but did not seem to influence acute energy balance. Appetite ratings were associated with modifications in PYY hormone concentrations.

The relationship between serum ghrelin levels and bone metabolism markers and severity anemia in non-diabetic hemodialysis patients; a pilot study

Background: Chronic kidney disease (CKD) is a consequence of progressive and irreversible destruction of nephrons, mainly due to uncontrolled diabetes mellitus and high blood pressure. Ghrelin is a peptide hormone which could play a substantial role in hunger sensation, may increase body fat percentage and might adjust the long-term body weight and is mostly secreted in the stomach. Objectives: This study aimed to evaluate the relationship between ghrelin levels and various biochemical and demographic indices in a group of non-diabetic hemodialysis patients. Patients and Methods: Around 39 non-diabetic patients undergoing hemodialysis in Hajar hospital at Shahrekord city were enrolled. Results: The mean age of patients was 57.10±20.20 years. Their mean weight was 56.65 ±16.25 kg. Their hemoglobin level mean was 10.43±1.84 g/dL. The serum ghrelin level had a positive but not significant correlation with the age, dialysis quality, dosage, calcium level, alkaline phosphatase (ALP), parathormone, vitamin D and hemoglobin in these patients. Conclusions: More studies in this subject of hemodialysis patients to define the exact role of ghrelin in hemodialysis patients are recommended.

Idalopirdine, a selective 5-HT6 receptor antagonist, reduces food intake and body weight in a model of excessive eating

Obesity, from early childhood onwards, is a common societal problem. The overconsumption of sweet, salty and high-fat products are the main factors that cause excessive weight gain. It is therefore necessary to search for new drugs that affect satiety centers and reduce the sense of hunger and caloric intake. It has been suggested that the blockade of 5-HT6 receptors may reduce food intake, and since idalopirdine is a clinically tested, selective 5HT6 receptor antagonist, it was chosen to be examined in animal models of obesity. The activity of idalopirdine was measured in the rat model of excessive eating. Animals were on a high caloric diet that consisted of milk chocolate with nuts, cheese, salted peanuts and condensed milk. During a four-week experiment, the rats had constant access to standard feed and water ad libitum. Idalopirdine was administered intraperitoneally at a dose 5 mg/kg b.w./day. To establish whether idalopirdine would effectively suppress the rebound hyperphagia that accompanies refeeding, it was administered after a 20 h food deprivation period. Pica behavior was evaluated after the administration of idalopirdine to confirm that the suppression of food intake was not caused by visceral illness. The effect of the four-week treatment with idalopirdine on the amount of peritoneal adipose tissue, and on lipid and carbohydrate profiles in rats was also examined. The statistical significance was calculated using the one-way ANOVA post-hoc Tukey Multiple Comparison Test or the two-way ANOVA post-hoc Bonferroni Multiple Comparison Test. Idalopirdine significantly reduced caloric intake and prevented the development of obesity in tested animals. Rats, that received idalopirdine, had a smaller amount of adipose tissue in the peritoneum as well as lower glucose, triglyceride and cholesterol levels in comparison to the control group. Moreover, an anorectic action was not caused by abnormalities of the gastrointestinal tract, such as nausea. The obtained results indicate that idalopirdine reduces caloric intake and could be considered for further tests as a potential treatment of obesity.

Hibiscus and lemon verbena polyphenols modulate appetite-related biomarkers in overweight subjects: a randomized controlled trial.

Plant-derived polyphenols have shown potential to alleviate obesity-related pathologies by a multi-targeted mechanism in animal models and human intervention studies. A dietary supplement based on a combination of Lippia citriodora (LC) and Hibiscus sabdariffa (HS) polyphenolic extracts was assayed in a double blind and placebo-controlled intervention study with 54 overweight subjects. Blood pressure, body weight, height, triceps, biceps and abdominal skinfold thickness, and arm and abdominal circumferences were taken at the baseline, 30 and 60 days of the intervention period. The validated Visual Analogue Scale used to record hunger and satiety-related sensations was passed at the beginning and at 15, 30, 45 and 60 days of the intervention. Subjective health status was assessed through the validated SF-36 questionnaire at the beginning and end of the study. Finally, plasma from fasting blood samples was obtained at the beginning, 30 and 60 days of the study. The results showed an improvement of anthropometric measurements, decreased blood pressure and heart rate and a more positive perception in the overall health status. We also observed that plant polyphenols increased anorexigenic hormones (glucagon-like peptide-1) and decreased orexigenic hormones (ghrelin). Based on previous evidence we postulate that AMP-activated protein kinase may have a role in such effects through its capability to modulate energy homeostasis, total daily energy expenditure and lipid management. Although further research may be required, we propose that this polyphenolic combination may be used for weight management by increasing long-term weight loss maintenance through the modulation of appetite biomarkers. This may help to avoid the undesired weight regain typical of calorie restriction diets.

The impact of post-resistance exercise protein consumption on subsequent appetite and daily energy intake of sarcopenic older men: a pilot study.

Because of its satiating effect, it has been widely purported that a high-protein beverage may reduce subsequent appetite and food intake in healthy aged individuals, therefore annihilating any supplemental effect. The goal of the study was to examine the impact of a post-exercise protein supplement from dairy products in the hours following resistance exercise on subsequent energy intake, sensation of hunger, appetite and satiety in sarcopenic older men. A randomized double-blind crossover study with three experimental conditions was performed. Nine sarcopenic older (64 ± 3years) men participated in three experimental conditions: post-exercise protein supplementation made from (1) cow's milk (13g of proteins); (2) rice milk (isocaloric protein-free beverage) and (3) water (control). Subsequent energy intake was measured with a test buffet and a food record over the rest of the day. Assessment of appetite, satiety and hunger were obtained by visual analogue scales at various times before and after the buffet. Appetite, feeling of hunger and satiety and subsequent energy intake were not significantly different between the three experimental conditions. However, when participants were supplemented with cow's milk, total fat intake during the day of the intervention was significantly lower than with other supplements (p ≤ 0.05). Post-exercise consumption of protein supplements made from dairy products appear not to compromise daily nutritional behavior and does not confer the anticipated negative impact on nutritional intake in sarcopenic older men.

No metabolic effects of mustard allyl-isothiocyanate compared with placebo in men

Background: Induction of nonshivering thermogenesis can be used to influence energy balance to prevent or even treat obesity. The pungent component of mustard, allyl-isothiocyanate (AITC), activates the extreme cold receptor transient receptor potential channel, subfamily A, member 1 and may thus induce energy expenditure and metabolic changes.Objective: The objective of our study was to evaluate the potential of mustard AITC to induce thermogenesis (primary outcome) and alter body temperature, cold and hunger sensations, plasma metabolic parameters, and energy intake (secondary outcomes).Design: Energy expenditure in mice was measured after subcutaneous injection with vehicle, 1 mg norepinephrine/kg, or 5 mg AITC/kg. In our human crossover study, 11 healthy subjects were studied under temperature-controlled conditions after an overnight fast. After ingestion of 10 g of capsulated mustard or uncapsulated mustard or a capsulated placebo mixture, measurements of energy expenditure, substrate oxidation, core temperature, cold and hunger scores, and plasma parameters were repeated every 30 min during a 150-min period. Subjects were randomly selected for the placebo and capsulated mustard intervention; 9 of 11 subjects received the uncapsulated mustard as the final intervention because this could not be blinded. After the experiments, energy intake was measured with the universal eating monitor in a test meal.Results: In mice, AITC administration induced a 32% increase in energy expenditure compared with vehicle (17.5 ± 4.9 J · min−1 · mouse−1 compared with 12.5 ± 1.2 J · min−1 · mouse−1, P = 0.03). Of the 11 randomly selected participants, 1 was excluded because of intercurrent illness after the first visit and 1 withdrew after the second visit. Energy expenditure did not increase after ingestion of capsulated or uncapsulated mustard compared with placebo. No differences in substrate oxidation, core temperature, cold and hunger scores, or plasma parameters were found, nor was the energy intake at the end of the experiment different between the 3 conditions.Conclusion: The highest tolerable dose of mustard we were able to use did not elicit a relevant thermogenic response in humans. This trial was registered at www.controlled-trials.com as ISRCTN19147515.

The genetics of obesity - Pathogenetic, clinical and diagnostic aspects

Due to its prevalence and its health-related, economic and social consequences, childhood and adult obesity is a complex, medical and civilizational problem, which has been on the increase in the last decade. The results of multi-center investigations reveal that genetic factors play an essential role in the etiopathogenesis of obesity, particularly in the case of extreme cases with very early onset. The Body Mass Index (BMI) is one of the most frequently used indicators of obesity and shows a strong genetic component with a 40-70% degree of heritability. The three types of genetically conditioned obesity are: (1) isolated (nonsyndromic) monogenic obesity, (2) syndromic monogenic obesity associated with dysmorphic features and/or congenital defects, caused by mutations in specific gene(s), (3) chromosomal aberrations, including submicroscopic changes. The most prevalent common (complex) obesity is linked to the presence of various changes in different genomic loci, which are subject to interactions and modifications by environmental (ethnic, dietary, lifestyle, bacterial flora, oxidative stress), as well as epigenetic (i.e., associated with DNA methylation, histone modification) and epistatic (gene-gene interaction) factors. Recent investigations using the modern methods of genome-wide association studies (GWAS), bioinformatics and proteomics, have made it possible to elucidate 8 key genes among the 97 genes most likely to play significant roles in the metabolic effects of obesity. The results of investigations on the pathogenesis of complex obesity do not as yet clarify the potential pathogenic significance of these genomic changes in humans. This article discusses the neuro-endocrinological regulation of the sensation of hunger and thirst, the clinical consequences of mutations in genes associated with the melanocortin pathway, and the features of the most common obesity syndromes, including syndromes conditioned by genomic imprinting. A diagnostic algorithm for cases of suspected syndromic obesity is proposed.

Ghrelin-mediated inhibition of the TSH-stimulated function of differentiated human thyrocytes ex vivo.

Ghrelin is a peptide hormone produced mainly in the gastrointestinal tract known to regulate several physiological functions including gut motility, adipose tissue accumulation and hunger sensation leading to increased bodyweight. Studies have found a correlation between the plasma levels of thyroid hormones and ghrelin, but an effect of ghrelin on the human thyroid has never been investigated even though ghrelin receptors are present in the thyroid. The present study shows a ghrelin-induced decrease in the thyroid-stimulating hormone (TSH)-induced production of thyroglobulin and mRNA expression of thyroperoxidase in a primary culture of human thyroid cells obtained from paranodular tissue. Accordingly, a trend was noted for an inhibition of TSH-stimulated expression of the sodium-iodine symporter and the TSH-receptor. Thus, this study suggests an effect of ghrelin on human thyrocytes and thereby emphasizes the relevance of examining whether ghrelin also influences the metabolic homeostasis through altered thyroid hormone production.

Effects of dark-chocolate on appetite variables and glucose tolerance: A 4 week randomised crossover intervention in healthy middle aged subjects

Cocoa is a well acknowledged polyphenol-rich functional product. However, the mechanisms and effects of cocoa products on glucose metabolism and appetite regulation are not clear.A crossover randomised study was carried out in twenty (4male; 16female) healthy middle-age (62.6±6.5yr) subjects with normal BMI (23.0±2.0kg/m2). Effects on postprandial glucose-, insulin- and subjective appetite responses to a preload (30min) of 70% dark-chocolate (DC), with and without a preceding 4-week DC intervention, were evaluated. SCFA (acetate, propionate and butyrate), BDNF, GLP-1, and PYY were determined in plasma at fasting. An isocaloric white-chocolate-like product (CP) was included asa control. DC increased (main effects; p<0.05) glucose- and insulin responses in comparison with CP. Postprandial hunger sensations were reduced (p<0.05), whereas acetate and propionate were higher (p<0.05) after 4-week DC intervention. The results suggest that cocoa may play a role in appetite regulation, however the unexpected increase in postprandial glucose- and insulin concentrations requires further investigation.

Hunger and Satiety Gauge Reward Sensitivity.

Many of the neurocircuits and hormones known to underlie the sensations of hunger and satiety also substantially alter the activity of the dopaminergic reward system. Much interest lies in the ways that hunger, satiety, and reward tie together, as the epidemic of obesity seems tied to the recent development and mass availability of highly palatable foods. In this review, we will first discuss the basic neurocircuitry of the midbrain and basal forebrain reward system. We will elaborate how several important mediators of hunger—the agouti-related protein neurons of the arcuate nucleus, the lateral hypothalamic nucleus, and ghrelin—enhance the sensitivity of the dopaminergic reward system. Then, we will elaborate how mediators of satiety—the nucleus tractus solitarius, pro-opiomelanocortin neurons of the arcuate nucleus, and its peripheral hormonal influences such as leptin—reduce the reward system sensitivity. We hope to provide a template by which future research may identify the ways in which highly rewarding foods bypass this balanced system to produce excessive food consumption.