Sensation Of Satiety Research Articles

Satiating Properties of Meat-Preparations: Role of Protein Content and Energy Density

Objective: To investigate the effects of three beef-based preparations (roast-beef, boiled beef, canned beef in jelly) on satiety and eating behavior.Methods: Ten male and ten female healthy volunteers (normal weight for height) were recruited. Three different studies were conducted, all with a within-subjects design. In Study 1, the effect of the beef-preparations on the specific satiety was evaluated by ad libitum consumption. In Study 2, the effect of the beef-preparations, proposed as a first course (preload) of a complete meal, on the total energy intake was explored. Subjects were asked to eat the beef-preloads (260g for women; 400g for men) in full, and then to consume as much as they wanted of a test meal. A no-load condition (ad libitum test meal consumption without any meat-preload) was included. In Study 3, the contribution of three different amounts of canned beef, served with a fixed amount of salad, on the desire to eat and satiety sensations over time was evaluated.Results: In Study 1, energy, weight and protein intakes were significantly affected by the type of beef-preparation, but not by pleasantness. In fact, specific satiety was reached with comparable amount of boiled meat and roast-beef, whilst canned meat was eaten in a higher amount, despite a lower rating of pleasantness. In Study 2, total energy was independent of the type of beef-preparation and was always lower than in the no-load condition; on the contrary, weight intake was similar in all conditions. From Study 3, a significant effect of time and low-energy protein food portion/time interaction on satiety ratings was observed.Conclusion: The satiating properties of the beef-preparations did not depend strictly on protein content; on the contrary, physical characteristics and, mainly, energy density seemed the most effective determinants. However, small portions of low-energy dense-protein foods seemed to be useful in modulating satiety sensations. On the whole, our results suggest that high protein intakes are not necessarily the only way to control food intake.

Application of labelled magnitude satiety scale in a linguistically-diverse population

The labelled magnitude scale (LMS) has been found to provide better discrimination of satiety sensations compared to a visual analogue scale (VAS). The perception of satiety in a linguistically-diverse population may produce differences in the numerical ratios due to language acquisition and diversity. The objective of this study was to investigate whether LMS based on perceived intensities of satiety is an appropriate methodology for a linguistically-diverse population. A total of forty three subjects (28 female, 15 male) were asked to quantify the semantic meaning of 47 English words denoting hunger/fullness at various intensities. Forty four percent of the subjects had English as their first language (EFL sub-group) with the remainder having a first language other than English (EOL sub-group). Words with ambiguous evaluation scores were removed and geometric means (GM) were calculated for each remaining words. Eleven final anchoring words were chosen for the bi-polar linear scale and the scale was constructed by setting the GM to +100 and −100 for each extreme. The types of words removed due to ambiguity differed between the two sub-groups as some words had no equivalent in some of the first languages of the EOL sub-group e.g. ravenous and voracious. The scale constructed was asymmetrical with phrases such as extremely full/hungry and very full/hungry located near to negative/positive ends of the linear scale. Phrases such as moderately full/hungry and slightly full/hungry were located within the central zone of the scale. Quantification of the semantic meaning of hunger/fullness words was not significantly different between sub-groups for the eleven phrases chosen as anchor. We conclude that, provided ambiguous words are avoided, labelled magnitude scales in English can be utilised to assess the perception of perceived satiety in a diverse population differing in their first language.

Meal-induced compositional changes in blood and saliva in persons with bulimia nervosa

BackgroundBinge eating episodes in persons with bulimia nervosa may to some extent be a result of disturbed sensations of hunger and satiety. It has been hypothesized that abnormal appetite sensations may be due to bulimia nervosa–related alterations in the release of hormones that are known to be involved in the physiologic regulation of appetite and metabolism. ObjectiveThe objective was to investigate whether circulating concentrations of the appetite-regulating peptides leptin and ghrelin and markers of metabolism (glucose and insulin) are different in persons with bulimia nervosa than in controls before and after intake of a meal and whether these changes may be reflected in saliva. DesignTwenty women with bulimia nervosa and 20 age- and sex-matched healthy controls participated. After an overnight fast, the subjects ate a standardized carbohydrate-rich breakfast. Whole saliva and blood were collected, and visual analogue scales for hunger and satiety were completed once before and continuously for 5 h after the breakfast. ResultsA lower pre- and postprandial whole saliva flow rate was found in subjects with bulimia nervosa, which might have been attributable to a concomitant intake of potentially xerogenic medication. Subjects with bulimia nervosa experienced reduced hunger, which could not be explained by pre- or postprandial alterations in circulating ghrelin, leptin, insulin, or glucose concentrations. ConclusionsThere were no apparent differences in the composition of blood and saliva between bulimia nervosa and control subjects, and meal-induced compositional changes in blood were not directly mirrored in saliva composition.

Monitoring Gastric Filling, Satiety and Gastric Emptying in a Patient with Gastric Balloon Using Functional Magnetic Resonance Imaging–-A Feasibility Report

Intragastric balloons are used for short term weight loss therapy in obese. It is possible to monitor the ballon with sonography, however this method is sometimes insufficient in obese patients. Therefore MRI seems to be a potential therapy-monitoring option. In this feasibility report we want to demonstrate the potential use of functional MRI in monitoring gastric filling, patient satiation and gastric emptying in a obese patient who previously received intragastric balloon placement. We selected one patient (male, 178 cm, 127 kg, BMI = 40,5 kg/m(2)) who recently received a gastric balloon and visualized gastric motility in presence of the gastric balloon before and after food intake. Fast cross-sectional images in one breathhold spin echo or gradient echo sequences were aquired. Real-time gastric motion was performed with cine mode. MRI offers perfect visualisation of gastric balloons in obese patients. Gastric filling and emptying can be monitored in correlation to patient satiety sensation. MRI can visualize the gastric balloon with degree of filling and possible leakages. Cine mode sequences demonstrate gastric motility and gastric wall peristalsis. MR is a valuable imaging alternative for patients with intragastric balloons.

Comparison of Anterior Gastric Wall and Greater Gastric Curvature Invaginations for Weight Loss in Rats

Many bariatric endoscopic or surgical procedures performed today reduce gastric capacity and/or induce an early sensation of gastric satiety, alone or in combination with a distal enteric intervention. A form of prosthetic wrap of the folded stomach was used in the past for treating obesity with a high rate of prosthesis-related reintervention. Nissen gastric fundoplication used in the treatment of gastroesophageal reflux disease induces a small but significant weight loss without gastric stapling, partitioning, or prosthesis-related morbidity. We recently reported greater gastric curvature invagination without stapling, partitioning or prosthesis use, for weight loss in rats. We now compare anterior gastric wall and greater gastric curvature invaginations for weight loss. The anterior invagination would be technically easier, should it be tested in humans. 20 rats were randomized in 2 groups. The anterior gastric wall of 10 rats was invaginated in the first group (AGW). The greater gastric curvature of 10 rats was invaginated in the second group (GGC). All animals were weighed weekly for 4 weeks. They were then autopsied on the 28th day. The mean body weight of the GGC group became statistically less than the AGW group at 21 days. The mean weight of the peritesticular fat pad and the mean gastric volume were not statistically different at 28 days (autopsy). Greater gastric curvature invagination significantly reduces body weight compared to anterior gastric wall invagination at 21 days.

Remapping the Body: Learning to Eat Again After Surgery for Esophageal Cancer

Surgery for esophageal cancer offers the hope of cure but might impair quality of life. The operation removes tumors obstructing the esophagus but frequently leaves patients with eating difficulties, leading to weight loss. Maintaining or increasing body weight is important to many patients, both as a means of returning to "normal" and as a means of rejecting the identity of the terminal cancer patient, but surgery radically alters embodied sensations of hunger, satiety, swallowing, taste, and smell, rendering the previously taken-for-granted experience of eating unfamiliar and alien. Successful recovery depends on patients' learning how to eat again. This entails familiarization with physiological changes but also coming to terms with the social consequences of spoiled identity. The authors report findings from in-depth interviews with 11 esophageal cancer patients, documenting their experiences as they struggle to achieve a process of adaptation that is at once physiological, psychological, and social.

Volume de iogurte light e sensações subjetivas do apetite de homens eutróficos e com excesso de peso

OBJETIVO: Avaliar, independentemente de outras variáveis, o efeito do volume de iogurte light sobre os parâmetros de ingestão alimentar de homens saudáveis. MÉTODOS: Foi feita incorporação de ar ao iogurte por adição de um produto comercialmente disponível -Emustab® - (6g/300ml) com posterior homogeneização em liqüidificador semi-industrial. Utilizaram-se três volumes de iogurte: 300, 450 e 600ml. Trabalhou-se com 20 participantes saudáveis, sendo 10 eutróficos, com índice de massa corporal entre 19 e 24,9kg/m² e 10 com excesso de peso, índice de massa corporal >25kg/m². Cada um deles recebeu um volume de iogurte em três diferentes dias, pela manhã, em jejum de 12 horas. Uma escala de analogia visual foi utilizada, num período de 4 horas e 30 minutos após ingestão de cada volume do iogurte, para avaliar sensações subjetivas de saciedade, fome e desejo por alimentos específicos. RESULTADOS: Os volumes do iogurte light afetaram a saciedade dos dois grupos estudados, sendo que o maior volume exerceu melhor essa ação (p<0,01). O maior escore para fome foi observado após ingestão do volume de 300ml, seguido de 450 e 600ml (p<0,01). O desejo por alimentos doces, salgados, gordurosos e lanches não foi influenciado pelo tempo e volume do iogurte em ambos os grupos estudados. A ingestão energética subseqüente ao experimento não diferiu estatisticamente entre os dias do estudo e o dia sem iogurte (p<0,05). CONCLUSÃO: Os resultados deste estudo sugerem que o volume de iogurte light, independentemente de outras variáveis, pode afetar a fome e a saciedade.

Characterization of obese individuals who claim to detect no relationship between their eating pattern and sensations of hunger or fullness

To study the phenomenon that obese subjects show considerable individual variability in their reported relationships between eating and sensations of hunger and fullness. A laboratory study of the relationship between eating behaviour traits and the episodic oscillations in sensations of hunger and fullness in response to obligatory, fixed energy breakfast (481 kcal) and lunch (675 kcal) meals. Obese subjects were divided into two groups based on their responses to four 'screening' questions associated with their habitual experience of hunger and fullness sensations before and after eating: those who experienced sensations of hunger and fullness related to eating (Related-R; n=20, body mass index (BMI)=42.4 kg/m(2)) and those for whom eating was not related to hunger or fullness sensations (Unrelated - UR; n=19, BMI=41.3 kg/m(2)). In addition, a control, lean group (Control - C; n=14, BMI=22.6 kg/m(2)) who experienced sensations of hunger and fullness related to eating was studied. The Three-Factor Eating Questionnaire (TFEQ) was used to measure the eating behaviour traits, disinhibition, restraint and hunger. Profiles of subjective appetite sensations were continuously monitored across the day using visual analogue scales. All groups displayed clear meal-related oscillations in subjective sensations of hunger, fullness, desire to eat and prospective consumption. In contrast, the TFEQ disinhibition and hunger scores (but not restraint scores) were significantly different (P<0.05) between the groups ((UR; D=13.5+/-0.5, H=10.0+/-0.5), R (D 7.5+/-0.6, H 6.1+/-0.4), C(D 3.7+/-0.5, H 3.7+/-0.5)). In addition, analysis of the intra-meal changes in subjective appetite sensations revealed that the UR group displayed a smaller meal-induced suppression of hunger and elevation of fullness. These data indicate that the reported relationship between eating and hunger/fullness was associated with obese individuals showing high or low disinhibition scores. In addition, the data suggest that the processes underlying disinhibition may be associated with a modulation of the recognition of meal-related satiety sensations.

Gastrointestinal hormones regulating appetite.

The role of gastrointestinal hormones in the regulation of appetite is reviewed. The gastrointestinal tract is the largest endocrine organ in the body. Gut hormones function to optimize the process of digestion and absorption of nutrients by the gut. In this capacity, their local effects on gastrointestinal motility and secretion have been well characterized. By altering the rate at which nutrients are delivered to compartments of the alimentary canal, the control of food intake arguably constitutes another point at which intervention may promote efficient digestion and nutrient uptake. In recent decades, gut hormones have come to occupy a central place in the complex neuroendocrine interactions that underlie the regulation of energy balance. Many gut peptides have been shown to influence energy intake. The most well studied in this regard are cholecystokinin (CCK), pancreatic polypeptide, peptide YY, glucagon-like peptide-1 (GLP-1), oxyntomodulin and ghrelin. With the exception of ghrelin, these hormones act to increase satiety and decrease food intake. The mechanisms by which gut hormones modify feeding are the subject of ongoing investigation. Local effects such as the inhibition of gastric emptying might contribute to the decrease in energy intake. Activation of mechanoreceptors as a result of gastric distension may inhibit further food intake via neural reflex arcs. Circulating gut hormones have also been shown to act directly on neurons in hypothalamic and brainstem centres of appetite control. The median eminence and area postrema are characterized by a deficiency of the blood-brain barrier. Some investigators argue that this renders neighbouring structures, such as the arcuate nucleus of the hypothalamus and the nucleus of the tractus solitarius in the brainstem, susceptible to influence by circulating factors. Extensive reciprocal connections exist between these areas and the hypothalamic paraventricular nucleus and other energy-regulating centres of the central nervous system. In this way, hormonal signals from the gut may be translated into the subjective sensation of satiety. Moreover, the importance of the brain-gut axis in the control of food intake is reflected in the dual role exhibited by many gut peptides as both hormones and neurotransmitters. Peptides such as CCK and GLP-1 are expressed in neurons projecting both into and out of areas of the central nervous system critical to energy balance. The global increase in the incidence of obesity and the associated burden of morbidity has imparted greater urgency to understanding the processes of appetite control. Appetite regulation offers an integrated model of a brain-gut axis comprising both endocrine and neurological systems. As physiological mediators of satiety, gut hormones offer an attractive therapeutic target in the treatment of obesity.

Effects of Exercise and a Low Carbohydrate Diet on Serum PYY Concentrations

Peptide tyrosine tyrosine (PYY) is a hormone produced by the gut, which, similar to leptin, is released into the circulation after food intake and contributes to sensations of satiety perhaps resulting in decreased caloric consumption. Advocates of low carbohydrate diets purport that by restricting carbohydrate intake, sensations of satiety are increased while appetite is decreased thus facilitating reductions in body mass. However, the effects of a low carbohydrate diet on serum PYY concentrations have not been evaluated. Exercise is also advised for the reduction of body mass, but the effects of exercise on serum PYY concentrations have not been well denned. PURPOSE: The purpose of this project was to examine the effects of a moderate intensity exercise program and low carbohydrate diet that facilitates weight loss on serum PYY concentrations in healthy adults. METHODS: Nineteen healthy adults who desired to lose weight engaged in brisk walking (∼50% VO2peak) for 30 minutes, 3 times per week for 7 weeks and were randomly assigned to either a low carbohydrate diet (Atkins diet; LoCho; n=9) or to maintain their current diet (Con; n=10). Aerobic fitness, body composition, dietary composition, and fasting serum PYY concentrations were measured at baseline and again at week 7. RESULTS: Aerobic fitness did not change in either group. Body mass (82 ± 8 vs. 82 ± 8 kg), fat mass (25 ± 4 vs. 25 ± 4 kg), and percent body fat (30 ± 3) did not change in Con from week 0 to week 7 (respectively). Body mass (96 ± 8 vs. 90 ± 9 kg), fat mass (30 ± 4 vs. 26 ± 4 kg), and percent body fat (32 ± 4 vs. 29 ± 3) were significantly (p < 0.05) reduced from week 0 to week 7 (respectively) in LoCho. Total dietary energy intake (11,831 ±2,036 vs. 10,923 ± 1,448 Kj/d), protein intake (1,761 ± 368 vs. 1,600 ± 208 Kj/d), carbohydrate intake (4,759 ± 368 vs. 4,709 ± 706 Kj/d), and fat intake (4,610 ± 1,458 vs. 3,989 ± 536 kj/d) did not change in Con, from week 0 to week 7 (respectively). Dietary protein (2,312 ± 584 vs. 2,558 ± 689 Kj/d), and fat intake (6,246 ± 1,482 vs. 4,295 ± 457 kj/d) did not change but there was a reduction (p < 0.05) in total energy (13,604 ± 1,691 vs. 9,381 ± 2,014 Kj/d) and carbohydrate intake (5,519 ± 1,065 vs. 2,516 ± 1,026 Kj/d), in LoCho from week 0 to week 7 (respectively). Serum PYY concentrations were not different in Con (146 ± 45 vs. 149 ± 41 pg/ml) or LoCho (110 ±42 vs. 115 ± 24 pg/ml) from week 0 to week 7 (respectively). CONCLUSION: These data indicate that participating in a low carbohydrate diet for 7 weeks does not reduce VO2peak in exercising people and does facilitate reductions in body mass. Moreover, a low carbohydrate diet may assuage feelings of hunger during reductions in body mass by maintaining serum PYY concentrations.

Unbalanced serum leptin and ghrelin dynamics prolong postprandial satiety and inhibit hunger in healthy elderly: another reason for the “anorexia of aging”

In healthy elderly, a reduction from the appetite and food intake of younger years has been defined as the "anorexia of aging," which may cause malnutrition. Leptin and ghrelin may alter the control of hunger and satiety and thus lead to anorexia. The aim of this study was to investigate how aging affects serum leptin and ghrelin concentrations in response to a meal and the relation of those hormones to hunger and satiety sensations. We studied 8 community-dwelling elderly (x +/- SD age: 78 +/- 1 y) subjects and 8 younger (29.5 +/- 1 y) control subjects. Under fasting conditions and for 4 h after an 800-kcal mixed meal, satiety and hunger were evaluated at intervals, by using a visual analogic scale. Blood samples for leptin, ghrelin, and insulin measurements were collected at the following times: 30 min before and immediately and 30, 60, 120, and 240 min after the meal. Postprandial satiety lasted significantly longer in the elderly than in the control subjects, and hunger was suppressed in the elderly throughout the observation. Fasting leptin was higher in the elderly than in the young (x +/- SE: 4.3 +/- 1.9 and 1.3 +/- 0.4 ng/mL, respectively; P < 0.05), and postprandial fluctuation was not significant. Fasting insulin also was significantly higher in the elderly than in the young (6.8 +/- 1.3 and 3.5 +/- 0.6 mU/L, respectively; P < 0.05), and the postprandial insulin rise was greater in the elderly. Fasting and postprandial ghrelin values did not differ significantly between the 2 groups. Insulin was inversely correlated with hunger and directly correlated with satiety scores. In healthy elderly, anorexigenic signals prevail over orexigenic signals, and they contribute to prolonged satiety and inhibition of hunger. This condition may lead to a calorie deficit and finally to malnutrition in the elderly.

Evaluation of Gastric Greater Curvature Invagination for Weight Loss in Rats

Many bariatric endocopic or surgical procedures performed today reduce gastric capacity and/or induce an early sensation of satiety, alone or in combination with a distal enteric intervention. A form of prosthetic gastric wrap was used in the past for treating obesity with a high rate of reintervention. Nissen gastric fundoplication used in the treatment of gastroesophageal reflux disease induces a small but significant weight loss. We report the effect of gastric greater curvature invagination on weight in rats. 30 rats were randomly divided into 3 groups. 10 rats in the first group (sham) were anesthesized and weighed. The rats from the second group (lap) were in addition submitted to a laparotomy plus visceral manipulation. In the third group (inv), invagination of the greater curvature of the stomach was added. All animals were weighed on the 7th and 21st days. They were then autopsied on the 21st day. The mean body weight of the invagination group became statistically less than the laparotomy and sham groups at 7 and 21 days. The mean weight of the peritesticular fat pad from the inv group was also significantly less than from the sham group but not different from the lap group. Gastric greater curvature invagination significantly decreases weight in rats.

Clinical, Psychopathological and Personality Correlates of Interoceptive Awareness in Anorexia nervosa, Bulimia nervosa and Obesity

Objective: To determine the levels of interoceptive awareness (IA), which measures the ability of an individual to discriminate between sensations and feelings, and between the sensations of hunger and satiety, in eating disorder patients and to identify the clinical, psychopathological and personal variables correlated with IA. Sampling andMethods: Sixty-one restrictor anorectics, 61 binge-purging anorectics, 104 purging bulimics, 49 obese subjects with binge eating disorder (BED) and 47 obese subjects without BED were compared. They were assessed with the Eating Disorder Inventory-2, the Temperament and Character Inventory, and the Beck Depression Inventory, and their clinical and sociodemographic features were recorded. Results: In all patients, the levels of IA were higher than the ‘normal’ ones; in bulimia nervosa, they were higher than in anorexia nervosa and obesity. Similar personal features and eating attitudes are shared by patients with bulimia nervosa and BED. In the total sample, the following variables independently correlate with IA: the Beck Depression Inventory, self- directedness and persistence. Conclusions: The importance of an altered IA in eating disorders is supported. Both depression and a perfectionist and poorly self-directive personality can lead to greater difficulties in discriminating hunger and satiety.

Gastrointestinal satiety signals I. An overview of gastrointestinal signals that influence food intake.

An overview is presented of those signals generated by the gastrointestinal (GI) tract during meals that interact with the central nervous system to create a sensation of fullness and satiety. Although dozens of enzymes, hormones, and other factors are secreted by the GI tract in response to food in the lumen, only a handful are able to influence food intake directly. Most of these cause meals to terminate and hence are called satiety signals, with CCK being the most investigated. Only one GI signal, ghrelin, that increases meal size has been identified. The administration of exogenous CCK or other satiety signals causes smaller meals to be consumed, whereas blocking the action of endogenous CCK or other satiety signals causes larger meals to be consumed. Satiety signals are relayed to the hindbrain, either indirectly via nerves such as the vagus from the GI tract or else directly via the blood. Most factors that influence how much food is eaten during individual meals act by changing the sensitivity to satiety signals. This includes adiposity signals as well as habits and learning, the social situation, and stressors.

Gastroduodenal motility

The neuromuscular function of the stomach and duodenum provides the mechanical forces that drive digestion and are responsible for sensations of satiety and of dyspepsia. This article reviews (1) the neuroendocrine factors controlling upper gastrointestinal motility, (2) noninvasive techniques to evaluate gastroduodenal motility, and (3) the pathophysiology and treatment of gastroparesis. Nutrients in the duodenum inhibit gastric emptying via a feedback pathway that involves release of cholecystokinin and serotonin (5-HT) from neuroendocrine cells; both act peripherally, cholecystokinin via cholecystokinin A receptors and serotonin via 5-HT3 receptors. The dorsal vagal complex plays a central role in the gastric inhibition mediated by tumor necrosis factor-alpha. The construction of maps that define intestinal movements in time and space has now been extended to the stomach. MRI compares favorably with the barostat in assessing gastric volume accommodation to meals and drugs and has the advantage of being noninvasive and showing contractions. Gastroparesis is increasingly recognized as a complication of end-stage liver disease; ascites plays no role in this, but portal hypertension stiffens the gastric walls and creates hypoxic conditions that may interfere with the neuromuscular functions of the stomach. Promising for the treatment of gastroparesis are clonidine, sildenafil, and intrapyloric botulinum toxin. Electrical stimulation triggers a vagally mediated relaxation of the stomach. Drugs may be designed that specifically act on 5-HT3, cholecystokinin, or TNF-alpha receptors. Spatiotemporal maps should boost the diagnostic yield from dynamic imaging of motility using ultrasound, computed axial tomography scan, or MRI and the understanding of the mechanical forces driving digestion. Symptomatic benefit in gastroparesis may derive more from improved accommodation than gastric emptying.

Treatment of dilated gastrojejunostomy with sclerotherapy.

Dilation of the gastrojejunostomy after gastric bypass may result in weight gain. Many surgical and medical treatments have met with poor results. A feasibility study of endoscopic sclerotherapy (ST) of the gastrojejunostomy was performed, based on the known risk of esophageal stricture in the treatment of esophageal varices. From 1991 to 2001, proximal Roux-en-Y gastric bypass (RYGBP) was performed on 685 patients, with a follow-up rate of 60% at 5 years. 20 patients were identified with dilated gastrojejunostomy (DGJ) by gastroscopy (EGD) performed for complaints of weight gain and marked increase in volume tolerance. Sclerotherapy of the gastrojejunostomy was performed during EGD. EGD was repeated 2 months after the sclerotherapy to measure the diameter of the anastomosis and observe any complications. Weight and sense of satiety were also measured, 2 and 6 months after ST. If necessary, the procedure was repeated to achieve a diameter of 10 mm. Reducing the diameter of the gastrojejunostomy to 9-10 mm was achieved in all patients, with an average of 1.3 treatments per patient. 15 patients (75%) lost weight. The average weight loss was 5.8 kg (ranging from 0.5 to 17.3 kg) in 2 months. Sclerotherapy successfully restores the desired anatomy of gastric bypass, but exercise and dietary discretion remain critical elements of sustained weight loss.

Satiety after vertical banded gastroplasty.

Early satiety following gastroplasty is due to the new anatomic conditions created by the operation and refers to a distressing or painful epigastric sensation after food consumption. Early satiation may act as an aversive stimulus, shaping eating habits and behaviour in such a way as to promote satisfactory weight loss and maintenance. This hypothesis was tested in patients who had undergone vertical banded gastroplasty (VBG). The duration of the sensation of early satiety was associated with the scores of questionnaires assessing eating behaviour, but seemed to be completely unrelated to the radiologically measured proximal pouch volume, energy intake and weight loss data. These findings suggest that cognitive factors play a substantial role in determining food intake and therefore in achieving weight goals following gastric restriction.

Meals with similar energy densities but rich in protein, fat, carbohydrate, or alcohol have different effects on energy expenditure and substrate metabolism but not on appetite and energy intake

It has been suggested that the satiating power of the 4 macronutrients follows the oxidation hierarchy: alcohol > protein > carbohydrate > fat. However, the experimental evidence for this is still scarce. The goal was to investigate the effects on appetite, energy intake and expenditure, and substrate metabolism of meals rich in 1 of the 4 macronutrients. Subjective appetite sensations, ad libitum food intake, energy expenditure, substrate metabolism, and hormone concentrations were measured for 5 h after breakfast meals with similar energy density and fiber contents but rich in either protein (32% of energy), carbohydrate (65% of energy), fat (65% of energy), or alcohol (23% of energy). Subjects were normal-weight, healthy women (n = 9) and men (n = 10) studied in a crossover design. There were no significant differences in hunger or satiety sensations or in ad libitum energy intake after the 4 meals. Diet-induced thermogenesis was larger after the alcohol meal (by 27%; P < 0.01), whereas protein produced an intermediary response (17%; NS) compared with carbohydrate and fat (meal effect: P < 0.01). After the alcohol meal, fat oxidation and leptin concentrations were greatly suppressed (meal effects, P < 0.0001 and P < 0.05) and triacylglycerol concentrations were as high as after the fat meal. Intake of an alcohol-rich meal stimulates energy expenditure but suppresses fat oxidation and leptin more than do isoenergetically dense meals rich in protein, carbohydrate, or fat. Despite differences in substrate metabolism and hormone concentrations, satiety and ad libitum energy intake were not significantly different between meals. Our data, therefore, do not support the proposed relation between the macronutrient oxidation hierarchy and the satiety hierarchy.

High-protein weight-loss diets: are they safe and do they work? A review of the experimental and epidemiologic data.

Recommendations for increased consumption of protein are among the most common approaches of popular or fad diets. This review summarizes the effects of dietary protein on satiety, energy intake, thermogenesis, and weight loss, as well as its effect on a variety of health outcomes in adults. In short-term studies, dietary protein modulates energy intake via the sensation of satiety and increases total energy expenditure by increasing the thermic effect of feeding. Whereas these effects did not contribute to weight and fat loss in those studies in which energy intake was fixed, one ad libitum study does suggest that a high-protein diet results in a greater decrease in energy intake, and therefore greater weight and fat loss. In terms of safety, there is little long-term information on the health effects of high-protein diets. From the available data, however, it is evident that the consumption of protein greater than two to three times the U.S. Recommended Daily Allowance contributes to urinary calcium loss and may, in the long term, predispose to bone loss. Caution with these diets is recommended in those individuals who may be predisposed to nephrolithiasis or kidney disease, and particularly in those with diabetes mellitus.

Oral, gastric and intestinal influences on human feeding

Direct infusion of specific nutrients or foods into different areas of the gastrointestinal tract, and techniques to distend the stomach, are useful tools enabling eating behaviour to be studied without the influence of orosensory factors. Using these techniques, the role of nutrients on gastrointestinal mechanisms of satiation as well as the interactions between the various systems in the control of feeding can be examined. Recent research in humans investigating the relative contribution of signals arising from different areas of the gastrointestinal tract has demonstrated that optimal control of appetite occurs only when orosensory signals are coupled with signals arising from the stomach and intestine. Interactions between gastric and intestinal signals do however combine to produce a more potent suppression of appetite and food intake than when either of these sites is stimulated alone. Gastric distension probably exerts a predominate influence on appetite suppression compared with intestinal stimulation, whereas nutrient stimulation of the intestine may function to modulate the sensations arising from gastric distension to elicit a meal-like sensation of satiety. In addition, these studies have highlighted that previous hypotheses concerning differential fat and carbohydrate satiation may require an orosensory component and probably do not reflect an inherent difference in the physiological effects of these macronutrients at the level of the GI tract. The interaction of orosensory influences, such as palatability, with negative feedback signals arising from the GI tract can be further studied using a combination of these techniques with measurement of microstructure of feeding in humans.