The effect of ethanol and alcoholic beverages on gastric emptying of solid meals in humans

AIMS: The systematic study of the effect of pure ethanol, alcoholic beverages, and their non-alcoholic components on gastric emptying of solid meals in humans. METHODS: 16 fasting healthy male subjects received once weekly 300 ml of the following solutions in random order: 4 and 10% (v/v) ethanol, beer, red wine, 5.5 and 11.4% (w/v) glucose, and water. The test solutions were given either together with a low caloric (270 kcal, n = 8) or a high caloric (740 kcal, n = 8) solid meal. Ultrasonography of the antrum was used to determine gastric emptying. RESULTS: Gastric half emptying time (t(1/2) ) of the high caloric solid meal with water was 131.3 +/- 7 min. The ingestion of 4 and 10% (v/v) ethanol (158.8 +/- 9.3 and 165.6 +/- 6.2 min, respectively), beer (163.1 +/- 11 min), and red wine (186.3 +/- 8.4 min) resulted in a significantly longer t(1/2) than water. The lag phases after 4 and 10% (v/v) ethanol, beer, and red wine were not significantly different from that of water (48.1 +/- 6.5 min). Compared with water, the ingestion of 5.5 and 11.4% (w/v) glucose resulted in a significantly longer t(1/2) (153.8 +/- 5 and 168.1 +/- 14.4 min, respectively) by increasing the duration of the lag phase. The high caloric meals resulted in a 2-fold prolongation of t(1/2) when compared with the low caloric meals. The effect of the solutions on the gastric emptying times, however, was similar for both test meals. CONCLUSIONS: (i) Ethanol in low concentrations of 4 and 10% (v/v) prolongs gastric emptying of solid meals; this inhibitory effect is not dose-dependent. (ii) Alcoholic beverages (beer and red wine) also result in a prolongation of gastric emptying. The inhibitory effect of red wine, but not of beer, is more pronounced than that of the corresponding ethanol concentration and amount. (iii) The inhibitory effect of ethanol and alcoholic beverages is mainly induced by a prolongation of the gastric emptying phase (without affecting the lag phase), whereas 5.5 and 11.4% (w/v) glucose prolong the lag phase in a dose-dependent manner. (iv) The inhibitory effect of ethanol, beer, and red wine on gastric emptying does not depend on the caloric content of the meal.     

Intake and gastric emptying of mono- versus disaccharides by rats

Eating and gastric emptying of mono- versus disaccharides were measured in rats which consumed each day a carbohydrate solution and, 5 h later, a restricted amount of a nutritionally adequate dry diet. When Wistar rats were offered 30% (wt/vol) sugar solutions for 60 min a day, energy intakes were smaller for glucose than for maltose or dextrin and smaller for invert sugar (fructose + glucose) than for sucrose. Sprague-Dawley rats consumed less energy from glucose than maltose when fed 60%, but not 15%, solutions of these sugars. Among Wistar rats accustomed to hypotonic carbohydrate meals, gastric emptying (kilocalories/minute) was slower for 30% glucose than 30% maltose and for 63% maltose than 21% maltose. These differences became obscured with continued exposure to highly hypertonic meals. Monosaccharides, being small, highly soluble molecules, can impart great osmolality to stomach contents. It appears that this osmotic property of monosaccharides tends to slow eating and gastric emptying.     

Long-term evolution of the effect of bran ingestion on meal-induced glucose and insulin responses in healthy man

The long-term effect (7 wk) of the addition in the diet of 20 g of wheat bran was studied in five healthy subjects. Blood glucose and plasma insulin were assayed during test-meals taking place before (I), then 10 days (II), 24 days (III), and 45 days (IV) after daily ingestion of wheat bran. Bran addition leads to a time progressive reduction of meal-induced glucose response. This effect was the strongest during meal III, at 30 min (from 7.38 +/- 0.11 to 5.0 +/- 1.11 mmol/l; p less than 0.05) and at 60 min (from 5.94 +/- 0.61 to 3.88 +/- 0.78 mmol/l; p less than 0.05). Insulin response remained identical during the first three test meals. It increased then in a significant manner during meal IV, at 60 min (From 45.5 +/- 12.3 to 61.8 +/- 8.9 microU/ml; p less than 0.02), and at 120 min (from 41.2 +/- 16.3 to 61.0 +/- 16.0 microU/ml; p less than 0.05). The causes of the reduction of glucose response could be potential gastric emptying and intestinal transit increases. The exact mechanism of the improved long-term glucose tolerance seen in brain is not obvious nor is the reason for the enhanced insulin response seen later.     

Ghrelin does not influence gastric emptying in obese subjects

OBJECTIVE: To evaluate the relationship between fasting plasma concentrations of ghrelin and gastric emptying in obese individuals compared with lean subjects. RESEARCH METHODS AND PROCEDURES: We included 20 obese patients (9 men and 11 women, BMI > 30 kg/m2) and 16 nonobese control subjects (7 men and 9 women, BMI < or = 25 kg/m2). Gastric emptying of solids (egg sandwich labeled with radionuclide) was measured at 120 minutes with (99m)Tc-single photon emission computed tomography imaging. Ghrelin and leptin were analyzed by radioimmunoassay and ELISA methods, respectively. RESULTS: The gastric half-emptying time was similar in obese men and women (67.8 +/- 14.79 vs. 66.6 +/- 13.56 minutes) but significantly shorter (p < 0.001) than in the control population (men: 88.09 +/- 11.72 minutes; women: 97.25 +/- 10.31 minutes). Ghrelin levels were significantly lower in obese subjects (131.37 +/- 47.67 vs. 306.3 +/- 45.52 pg/mL; p < 0.0001 in men and 162.13 +/- 32.95 vs. 272.8 +/- 47.77 pg/mL; p < 0.0001 in women). A negative correlation between gastric emptying and fasting ghrelin levels was observed only in lean subjects (y = -0.2391x + 157.9; R2 = 0.95). Also, in the lean group, ghrelin was the only significant independent determinant of gastric emptying, explaining 98% of the variance (adjusted R2) in a multiple regression analysis. DISCUSSION: This report shows that, in humans, gastric emptying is faster in obese subjects than in lean controls and that, whereas ghrelin is the best determinant of gastric kinetics in healthy controls, this action is lost in obesity.     

Thermic effect of feeding carbohydrate, fat, protein and mixed meal in lean and obese subjects

The thermic effect of 1.67 MJ (400 kcal) of carbohydrate (glucose), fat, protein and mixed meal were examined in 11 lean and 11 obese subjects by indirect calorimetry. The changes in metabolic rate in response over 90 min period (30-120 min after the meal) to the different meals were compared with that seen after a similar volume of low calorie drink. The thermic effects of glucose and protein were not significantly different between lean and obese subjects. Obese subjects showed very little increase in metabolic rate following ingestion of fat (-0.9 +/- 2.0%, mean +/- SEM) and this was significantly different from that seen in lean subjects (14.4 +/- 3.4%). The thermogenic response to mixed meal was also significantly lower in obese subjects when expressed as percentage change (12.9 +/- 2.3% compared to 25.0 +/- 4.8%). There was no evidence for delay in gastric emptying times for glucose and fatty meal in the six obese subjects in whom these were measured. We conclude that obese subjects show a reduced thermogenic response to fat.     

A simple isotope method for studying of gastric emptying of solid foods

A simple isotope method is explained by the authors for noninvasive functional evaluation of the gastric emptying of solid meal. According to the results of in vitro measurements suitable solid phase labelling was provided by boiling the egg traced with injected Tc-99m-pertechnetate. The evaluation of gastric emptying by means of test meal containing the radiolabelled boiled egg is simple, inexpensive and the radiation hazard is minimal. In cases of intact stomach the gastric emptying of solids (T2 = 115.1 +/- 12.4 min) were significantly slower, than in cases of Billroth I (T2 : 66.7 +/- 6.9 min, p less than 0.01) and Billroth II (T2 = 28.8 +/- 3.3 min, p less than 0.001) resections. Similarly, there was a significant difference (p less than 0.001) between the mean half time values of the two operated groups.     

Alpha-amylase (EC 3.2.1.1) susceptibility rather than viscosity or gastric emptying rate controls plasma responses to starch in healthy humans

The relationship between starch alpha-amylase (EC 3.2.1.1) susceptibility, plasma responses and gastric emptying rates has been investigated in humans. Nine randomly chosen healthy subjects were given three carbohydrate test meals (25 g starch or equivalent glucose units): two maize starch pastes with (a) 240 (S24) or (b) 500 (S50) g amylose/kg, and a glucose solution (GS). At 30 min, in vitro starch alpha-amylolysis was 48 (SD 4)% for S24 and 35 (SD 4)% for S50. Test meals differed in viscosity (mPa x s: S24, 54,000; S50, 190; GS, 4). Carbohydrates were labelled with 99mTechnetium and isotope gastric emptying was measured by external gamma counting. Carbohydrate isotopic gastric emptying patterns were exponential. Half gastric emptying time (min) was significantly (P less than 0.05) shorter for S50 (19(SD 2] than for GS (26(SD 2] or S24 (29(SD 2]. No correlation was found between half gastric emptying time and plasma response values. Values for peak insulin (pmol/l) above fasting were significantly (P less than 0.05) different: GS, 306 (SD 11); S24, 227 (SD 11); S50, 187 (SD 11). It is concluded that alpha-amylase susceptibility of the test carbohydrates is a determining factor in the insulin response of healthy subjects, while viscosity of the test meals and gastric emptying rate have no effect.     

The oligosaccharide α-cyclodextrin has modest effects to slow gastric emptying and modify the glycaemic response to sucrose in healthy older adults

In healthy older subjects, the glycaemic response to carbohydrate-containing meals is dependent on gastric emptying and intestinal absorption; when the latter is slowed, the magnitude of the rise in glucose is attenuated. The oligosaccharide α-cyclodextrin has been reported to diminish the glycaemic response to starch in young adults; this effect has been attributed to the inhibition of pancreatic amylase. We examined the effects of α-cyclodextrin on gastric emptying of, and the glycaemic and insulinaemic responses to, oral sucrose in healthy older subjects; as sucrose is hydrolysed by intestinal disaccharides, any effect(s) of α-cyclodextrin would not be attributable to amylase inhibition. A total of ten subjects (seven males and three females, age 68-76 years) were studied on 2 d. Gastric emptying, blood glucose and serum insulin were measured after ingestion of a 300 ml drink containing 100 g sucrose, labelled with (99m)Tc-sulphur colloid, with or without 10 g α-cyclodextrin. Gastric emptying was slowed slightly by α-cyclodextrin; this effect was evident between 135 and 195 min and was associated with a slight increase (P < 0·05) in distal stomach retention. After α-cyclodextrin, blood glucose was slightly less (P < 0·05) at 60 min, and serum insulin was less (P < 0·0005) at 90 and 120 min. There was no difference in the incremental areas under the curve (iAUC) for blood glucose, but there was a trend for the iAUC for serum insulin to be lower (P = 0·09) after α-cyclodextrin. We conclude that in a dose of 10 g, α-cyclodextrin has modest effects to slow gastric emptying of, and modify the glycaemic and insulinaemic responses to, oral sucrose, probably due to delayed intestinal carbohydrate absorption.     

Physical properties of starch meals in vivo and in vitro and their influence on gastric emptying and oral glucose tolerance test.

In study A, consisting of four groups of six subjects each, we measured the differences in pH, viscosity, and osmolality of in vivo and in vitro samples of steamed rice, congee, and 16.6 and 5% glucose solutions in 300-ml volumes. The physical properties of starch meals in vivo are different from in vitro samples, which may account for discrepancies among previous studies of glucose tolerance and gastric emptying. In study B, test meals of 300 ml of steamed rice, congee, 16.6% glucose, 5% glucose or a combined congee-metoclopramide meal (in which 10 mg metoclopramide i.v. was given 15 min before the congee was eaten) were given to seven subjects. Blood samples were taken, and the serum glucose and insulin responses were determined. The meals were labeled with 99mTc pentetic acid microcapsules, and the gastric emptying rates were calculated. Metoclopramide increased the gastric emptying of congee to that approaching steamed rice. The incremental glucose response to steamed rice was greater than that to congee, but the incremental insulin response was greatest with congee plus metoclopramide. The physical form of the food influences the blood glucose and insulin response and the rate of gastric emptying. The gastric emptying rate may be the major mechanism for the increased insulin response.     

Method for the quantitation of gastric emptying time of gel test meals

Isotopic markers were developed to allow measurement of the gastric emptying times of homogeneous and nonhomogeneous gel meals. Meals containing the dietary fibers psyllium and guar gum presented as homogeneous, viscous gels while meals containing the synthetic polymer polycarbophil presented as discrete gel particle-water mixtures. Fiber meals were labeled differently than polycarbophil meals. Fiber meals were labeled with 51Cr-CM-Sephadex. The marker was uniformly suspended in meals containing at least 1% guar or 2% psyllium. In contrast, polycarbophil particles were labeled by hydrating the dried granules with saline in which Na2(51)CrO4 had been dissolved. Use of the markers to measure gastric emptying was demonstrated in dogs fitted with duodenal cannulas. Half of the fiber meals emptied from the stomach in about 40 min without significant dilution by secretions. In contrast, only 8% of the polycarbophil particles emptied by 90 min. Particle-specific labeling of polycarbophil was important because the meal effluent was diluted extensively by secretions. We conclude that 51Cr-CM-Sephadex and soluble Cr-51 may be used as meal markers for estimation of the gastric emptying times of certain homogeneous and nonhomogeneous gel-type meals, respectively.     

Gastric emptying in infants with or without gastro-oesophageal reflux according to the type of milk

The present study was designed to determine the effects of milk composition and the influence of gastro-oesophageal reflux (GOR) on gastric emptying. Cineoesogastrocintigraphy (COGS) was performed in 201 infants between 0-1 year of age in order to detect GOR, and provided a means of estimation of the gastric emptying (GE). Ninety infants appeared free from GOR and constituted the control group; 111 had GOR. There infants were fed human milk or various standard formulae. In addition, 20 infants fed a whey-hydrolysate formula were tested. An appropriate volume of milk was marked with sulfur-colloid Tc (200 microcuries). Measurements of gastric radioactivity were made 30 min and 120 min after ingestion. For the whole population, the infants with GOR had slightly more rapid GE after 30 min (P less than 0.05), but, for the same type of milk, there was no significant difference between GOR and controls. GE did not differ with age or sex, but differed mainly according to the type of milk. In the control group, gastric residual content (GRC) at 120 min was 18 +/- 11 per cent with human milk (n = 7), 16 +/- 21 per cent with whey-hydrolysate formula (n = 8), 25 +/- 17 per cent with acidified formula (n = 13), 26 +/- 19 per cent with whey-predominant formula (n = 22), 39 +/- 17 per cent with casein-predominant formulae (n = 20), 47 +/- 19 per cent with follow-up formulae (n = 16) and 55 +/- 19 per cent with cow's milk (n = 12).(ABSTRACT TRUNCATED AT 250 WORDS)     

Changes in intragastric meal distribution are better predictors of gastric emptying rate in conscious pigs than are meal viscosity or dietary fibre concentration

The effect of dietary fibre on the gastric emptying rate of solids is controversial. Similarly, the mechanisms by which it modulates food intake are partially unknown. Gastric emptying and proximal v. distal stomach filling were evaluated in triplicate on four conscious pigs using scintigraphic imaging. Each animal received in an isoenergetic manner a concentrate low-fibre diet enriched in starch (S) and two high-fibre diets based on sugar beet pulp (BP) or wheat bran (WB). All meals had the same viscosity before ingestion (100.0-100.5 Pa.s). Viscosity of the gastric contents was measured in four additional animals fitted with a gastric cannula. The gastric emptying rate of BP diet was significantly slower than S and WB diets (t1/2 78.4 (sem 5.68), 62.8 (sem 10.01) and 111.6 (sem 10.82) min for S, WB and BP diets respectively, P<0.05). For BP diet only, rate of distal stomach filling was steady during the first 120 min after the meal whereas that of S and WB diets decreased in an exponential manner. Numerous backflow episodes from the distal into the proximal stomach were observed for BP diet that generated the larger intragastric viscosity (0.26 (sem 0.03), 0.3 (sem 0.02) and 0.52 (sem 0.002) Pa.s for S, WB and BP respectively). In conclusion, viscosity of the meal or the percentage total fibre, unlike viscosity of the gastric contents, are poor predictors for emptying. The reduced emptying rate observed with BP is associated with major changes in intragastric distribution of the meal absent with WB and S diets.     

Gastric acid secretion, gastrin release, and gastric emptying in humans as affected by liquid meal temperature

We investigated the effect of the temperature of a liquid meal on intragastric temperature, gastric acid secretion, gastrin release, and gastric emptying in normal human subjects. Coffee (360 mL) was infused into the stomach through a nasogastric tube at 58 (steaming hot), 37, or 4 degrees C (ice cold). Intragastric temperature, measured by an intragastric temperature sensor attached to the nasogastric tube, returned to body temperature 16.7 +/- 2.7 min after the hot meal and 23.8 +/- 1.1 min after the cold meal. Gastric acid secretion increased after hot, warm, and cold coffee but the initial temperature of the meal had no effect on gastric acid secretion. The temperature of the meal also had no effect on serum gastrin concentrations, which increased significantly after all the meals. Gastric emptying of hot, warm, or cold coffee meals was similar. These findings indicate that over a wide temperature range, the temperature of a liquid meal has little effect on gastric function in humans.     

Effects of xylitol on gastric emptying and food intake

We studied the effects of xylitol, the pentose-sugar alcohol, on gastric emptying of the solid-food component of a complex meal. Gastric emptying was measured in human volunteers by utilizing a standardized radiolabeled scrambled-egg meal. After ingestion of 25 g xylitol, gastric emptying was markedly prolonged (T-1/2 58 +/- 5 min control vs 91 +/- 7 min after xylitol [p less than 0.01]). Since delayed gastric emptying may affect food intake, we evaluated the effects of xylitol on calorie intake. Food intake after oral preloading with water resulted in intake of 920 +/- 60 kcal vs 690 +/- 45 kcal after 25 g of xylitol. In contrast, a preload of glucose, fructose, or sucrose failed to suppress food intake. Although xylitol decreased food intake and also delayed gastric emptying, these effects may be unrelated. Our data suggest a role for xylitol as a potentially important agent in dietary control.     

Plasma ghrelin concentrations are lower in binge-eating disorder

Binge-eating disorder (BED), characterized by binge meals without purging afterward, is found in about 30% of obese individuals seeking treatment. The study objective was to ascertain abnormalities in hormones influencing appetite in BED, especially ghrelin, an appetite-stimulating peptide, which was expected to be elevated. Measurements were made of plasma insulin, leptin, glucagon, cholecystokinin, and ghrelin, as well as glucose following an overnight 12-h fast, prior to and after ingestion (from 0 to 5 min) of a nutritionally complete liquid meal (1254 kJ) at 0830 h, at -15, 0, 5, 15, 30, 60, 90, and 120 min. Appetite ratings including hunger and fullness were also obtained. An acetaminophen tracer was used to assess gastric emptying rate. Three groups of comparably obese women (BMI = 35.9 +/- 5.5; % body fat = 44.9 +/- 4.7) participated: 12 nonbinge eating normals (NB), 14 subthreshold BED, and 11 BED. The BED subjects, compared to NB subjects, had lower baseline ghrelin concentrations prior to the meal, a lower area under the curve (AUC), with lower levels at 5, 15, 30, 90, and 120 min, and a smaller decline in ghrelin postmeal (all P < 0.03). The other blood values did not differ among groups, and neither did gastric emptying rate nor ratings of fullness. The BED subjects were then randomly assigned to treatment with cognitive-behavior therapy and diet (n = 5) or to a wait-list control (n = 4). Baseline ghrelin (P = 0.01) and AUC increased (P = 0.02), across both conditions, in which most subjects (7 of 9) stopped binge eating. The lower fasting and postmeal plasma ghrelin levels in BED are consistent with lower ghrelin levels in obese compared to lean individuals and suggests downregulation by binge eating.     

The effect of dietary fibre isolates on gastric secretion, acidity and emptying

1. In six volunteers, the effect of intragastric administration of different water-soluble chemical isolates of dietary fibre on gastric secretion, acidity and emptying was studied. 2. At 30 min after administration of the test meals, the stomach contents were completely aspirated and the volume, pH, phenol red concentration, total titratable acidity and different electrolytes were measured. 3. Compared with the control meal, the pH and unionized (combined) hydrogen concentrations were significantly higher (P less than 0.05) following most of the fibre-containing meals, while the total titratable acid concentration was not significantly different. None of the fibre-containing meals appreciably altered the volume or type of gastric secretion but had a low-grade variable effect on gastric emptying. 4. It is concluded that most dietary fibre isolates, although having a definite and notable buffering effect on the acid in the stomach, have a minimal effect on gastric secretion and a variable and small effect on gastric emptying.     

Xylitol vs glucose: effect on the rate of gastric emptying and motilin, insulin, and gastric inhibitory polypeptide release

The effect of xylitol and glucose on the rate of gastric emptying and intestinal transit and on motilin, gastric inhibitory polypeptide (GIP), and insulin release were studied in human volunteers. A single oral dose of 200 mL water containing 30 g glucose or 30 g xylitol, mixed with a 99mtechnetium-tin (99mTc-Sn) colloid, was used. Similar dosing without the label was used in motilin, GIP, and insulin studies. Xylitol decreased the rate of gastric emptying but concomitantly accelerated intestinal transit compared with glucose. The half-times for gastric emptying were 77.5 +/- 4.6 and 39.8 +/- 3.4 min after ingestion of xylitol and glucose solutions, respectively. Glucose suppressed motilin and stimulated GIP secretion; xylitol stimulated motilin secretion but had no effect on GIP, which is currently the main candidate for the role of enterogastrone. The accelerated intestinal transit and increase in plasma motilin observed after xylitol ingestion were thought to be causally related to the diarrhea and gastrointestinal discomfort produced by it.     

2型糖尿病患者胃排空影响因素分析

目的评估2型糖尿病患者胃排空和病程、血糖、血管病变及血清维生素B12的关系。方法选取2009年10月-2010年5月上海市普陀区中心医院内分泌科住院2型糖尿病患者100名及糖调节正常者40名,口服胃助显剂后超声检测15、30、45、60、759、0 min胃排空率,并计算半排空和全排空时间。每位受试者测空腹及早餐后血糖、糖化血红蛋白、血清维生素B12。分析糖尿病患者胃排空影响因素。结果口服胃助显剂后,病程5年以上糖尿病患者胃半排空和全排空时间较糖调节正常者和病程小于5年患者显著延长;15、30、456、0 min胃排空率明显小于糖调节正常组和5年以下糖尿病患者。大量白蛋白尿患者较尿白蛋白阴性患者45、607、5 min胃排空率下降、全排空时间延长。糖尿病患者胃排空时间与血清维生素B12水平和早餐后2 h血糖负相关。结论超声方法可反映糖尿病患者胃排空。长期高血糖患者胃排空明显减慢。糖尿病胃轻瘫可能与微血管病变及维生素B12缺乏有关。胃排空减慢可能通过延缓糖尿病患者碳水化合物吸收降低餐后血糖波动。     

Gastric emptying and intestinal absorption of a low-carbohydrate sport drink during exercise

The purpose of this study was to determine if lowering carbohydrate (CHO) concentration in a sport drink influences gastric emptying, intestinal absorption, or performance during cycle ergometry (85 min, 60% VO(2peak)). Five subjects (25 +/- 1 y, 61.5 +/- 2.1 mL . kg(-1) . min(-1) VO(2peak)) ingested a 3% CHO, 6% CHO, or a water placebo (WP) beverage during exercise. Gastric emptying was determined by repeated double sampling and intestinal absorption by segmental perfusion. Total solute absorption and plasma glucose was greater for 6% CHO; however, neither gastric emptying, intestinal water absorption, or 3-mi time trial performance (7:58 +/- 0:33 min, 8:13 +/- 0:25 min, and 8:25 +/- 0:29 min, respectively, for 6% CHO, 3% CHO, and WP) differed among solutions. These results indicate lowering the CHO concentration of a sport drink from 6% CHO does not enhance gastric emptying, intestinal water absorption, or time trial performance, but reduces CHO and total solute absorption.     

No effect of glucagon-like peptide-1 on short-term satiety and energy intake in man

Centrally administered glucagon-like peptide-1 (GLP-1) inhibits feeding in fasted rats, but its role in human satiety has been largely unexplored. The present study investigated the effect of peripheral GLP-1 infusion on gastric emptying and satiety in man. Ten non-obese male subjects were infused in a randomized single-blind within-subject crossover study using saline infusion as control. They received either a GLP-1 infusion (1.2 pmol/kg per min) or a saline infusion for 1 h, at 18.00 hours. At 20 min after starting the infusion the gastric emptying of a 400 ml water load was measured. Subjects completed behavioural self-rating scales to assess hunger and satiety. After 40 min subjects were given a buffet meal ad libitum and their food intake was recorded. GLP-1 infusion raised circulating GLP-1 concentrations to approximately twice those seen following a meal. It did not affect circulating insulin levels but caused a small fall in glucose levels. Gastric emptying of the water load was significantly delayed by the GLP-1 infusion. Energy intake from the buffet was unaffected by GLP-1 infusion. Self-assessment of hunger and satiety was similarly unaffected by the infusion before the buffet meal, although subjects tended to be less hungry after the buffet meal following GLP-1 infusion (P < 0.09). GLP-1 infusion delayed gastric emptying but had a minimal effect on food intake and satiety. This study casts doubts on whether GLP-1 is a major satiety factor in man, although a raised circulating plasma glucose level, as would normally occur postprandially, might be necessary for GLP-1 to increase satiety.