Relation between food intake and visual analogue scale ratings of appetite and other sensations in healthy older and young subjects

Effects of acute and longer-term dietary restriction on upper gut motility, hormone, appetite, and energy-intake responses to duodenal lipid in lean and obese men

BACKGROUND

A 4-d 70% energy restriction enhances gastrointestinal sensitivity to nutrients associated with enhanced energy-intake suppression by lipid. To our knowledge, it is unknown whether these changes occur with 30% energy restriction and are sustained in the longer term.

OBJECTIVES

We hypothesized that 1) a 4-d 30% energy restriction would enhance effects of intraduodenal lipid on gastrointestinal motility, gut hormones, appetite, and energy intake in lean and obese men and 2) a 12-wk energy restriction associated with weight loss would diminish effects of acute energy restriction on responses to lipid in in obese men.

DESIGN

Twelve obese males were studied before (day 0) and after 4 d (day 5), 4 wk (week 4), and 12 wk (week 12), and 12 lean males were studied before and after 4 d of consumption of a 30% energy-restricted diet. On each study day, antropyloroduodenal pressures, gut hormones, and appetite during a 120-min (2.86-kcal/min) intraduodenal lipid infusion and energy intake at a buffet lunch were measured.

RESULTS

On day 5, fasting cholecystokinin was less, and ghrelin was higher, in lean (P < 0.05) but not obese men, and lipid-stimulated cholecystokinin and peptide YY and the desire to eat were greater in both groups (P < 0.05), with no differences in energy intakes compared with on day 0. In obese men, a 12-wk energy restriction led to weight loss (9.7 ± 0.7 kg). Lipid-induced basal pyloric pressures (BPPs), peptide YY, and the desire to eat were greater (P < 0.05), whereas the amount eaten was less (P < 0.05), at weeks 4 and 12 compared with day 0.

CONCLUSIONS

A 4-d 30% energy restriction modestly affects responses to intraduodenal lipid in health and obesity but not energy intake, whereas a 12-wk energy restriction, associated with weight-loss, enhances lipid-induced BPP and peptide YY and reduces food intake, suggesting that energy restriction increases gastrointestinal sensitivity to lipid. This trial was registered at the Australian New Zealand Clinical Trials Registry (www.anzctr.org.au) as 12609000943246.

Potential benefits of satiety to the consumer: scientific considerations

Foods and dietary patterns that enhance satiety may provide benefit to consumers. The aim of the present review was to describe, consider and evaluate research on potential benefits of enhanced satiety. The proposal that enhanced satiety could only benefit consumers by a direct effect on food intake should be rejected. Instead, it is proposed that there is a variety of routes through which enhanced satiety could (indirectly) benefit dietary control or weight-management goals. The review highlights specific potential benefits of satiety, including: providing appetite control strategies for consumers generally and for those who are highly responsive to food cues; offering pleasure and satisfaction associated with low-energy/healthier versions of foods without feeling 'deprived'; reducing dysphoric mood associated with hunger especially during energy restriction; and improved compliance with healthy eating or weight-management efforts. There is convincing evidence of short-term satiety benefits, but only probable evidence for longer-term benefits to hunger management, possible evidence of benefits to mood and cognition, inadequate evidence that satiety enhancement can promote weight loss, and no evidence on which consumers would benefit most from satiety enhancement. The appetite-reducing effects of specific foods or diets will be much more subtle than those of pharmaceutical compounds in managing hunger; nevertheless, the experience of pharmacology in producing weight loss via effects on appetite suggests that there is potential benefit of satiety enhancement from foods incorporated into the diet to the consumer.

A pilot exploration of symptom trajectories in adolescents with cancer during chemotherapy

BACKGROUND

Chemotherapy is frequently administered in repetitive cycles. Adolescents with cancer have multiple symptoms related to chemotherapy, but knowledge of symptom trajectories across a cycle is limited. Examining trajectories over a cycle may reveal key periods to manage symptoms.

OBJECTIVES

The aims of this pilot were to describe the trajectory of symptoms (pain, sleep, appetite, nausea, fatigue) and biological and behavioral variables (anxiety, stress, hematologic function) across 1 cycle and examine relationships between variables.

METHODS

Nine adolescents with cancer within 6 months of diagnosis participated. Data were collected by surveys, chart review, and biologic measures on days 1 and 2 of the cycle, 1 week later (nadir), and day 1 of the following cycle. To evaluate the trajectory, a simple random-effects repeated-measures analysis was computed.

RESULTS

The significant trajectories were fatigue (P = .003), difficulty sleeping (P = .032), and nausea (P = .04). Most of the adolescents reported some anticipatory anxiety about receiving chemotherapy. Significant correlations between symptoms and biobehavioral variables included anticipatory anxiety and nausea (r = .86, P = .003), trait anxiety and fatigue (r = -0.82, P < .001), and stress and pain (r = 0.78, P = .039).

CONCLUSIONS

Multiple symptoms were experienced across the cycle. Three symptoms displayed significant trajectories indicating that patterns of symptoms may be anticipated.

IMPLICATIONS FOR PRACTICE

Pilot findings suggest that monitoring symptoms, stress, and anxiety across a cycle is important, not only during chemotherapy administration, but also prior to being admitted for chemotherapy.

Satiety responsiveness and eating behavior among Chilean adolescents and the role of breastfeeding

Objective

To determine patterns of satiety responsiveness and its relationship to eating in the absence of hunger (EAH), in a cohort of adolescents. We also assessed whether sex, BMI and duration of breastfeeding, during infancy, predicted satiety responsiveness and eating behavior at 16 years.

Methods

Adolescents (n=576) from a longitudinal cohort, that began as an iron deficiency anemia preventive trial, participated in an unlimited breakfast after an overnight fast, and reported satiety response on a visual analogue scale after the meal, followed by an EAH procedure. Height, weight and body composition were measured before breakfast. Latent profile analysis generated profiles that captured individual differences in satiety responsiveness. Multivariable regressions, adjusted for potential confounders, evaluated the association between: 1) satiety responsiveness and EAH, and 2) breastfeeding in infancy, satiety responsiveness and EAH in adolescence.

Results

Participants were on average 16.7-years-old, 48% female, 37% overweight/obese and 76% were breastfed as the sole source of milk for < 6 months. We found three latent profiles of satiety responsiveness: 1. “responsive” (49%); 2. “not responsive” (41%); 3. “still hungry” (10%). Participants in the “not responsive” or “still hungry” profile were more likely to eat during the EAH procedure (OR=2.5, 95%CI 1.8–3.6). Being breastfed for < 6 months was related to higher odds of being in the “not responsive” or “still hungry” profile (OR 1.8, 95%CI 1.2–2.6) and EAH (OR=2.2, 95% CI 1.4–3.3). Satiety responsiveness was not influenced by sex and overweight/obesity.

Conclusion

After an ad libitum meal, we found varied satiety responses, which related to EAH. Furthermore, shorter breastfeeding duration was associated with poorer satiety response and higher consumption during an EAH procedure. Understanding if breastfeeding influences the development of satiety responsiveness and eating behavior may be important in an era characterized by abundant calorie-dense foods and a plethora of environmental cues promoting consumption.

Acute aerobic exercise differentially alters acylated ghrelin and perceived fullness in normal-weight and obese individuals

Adiposity alters acylated ghrelin concentrations, but it is unknown whether adiposity alters the effect of exercise and feeding on acylated ghrelin responses. Therefore, the purpose of this study was to determine whether adiposity [normal-weight (NW) vs. obese (Ob)] influences the effect of exercise and feeding on acylated ghrelin, hunger, and fullness. Fourteen NW and 14 Ob individuals completed two trials in a randomized counterbalanced fashion, including a prior exercise trial (EX) and a no exercise trial (NoEX). During the EX trial, the participants performed 1 h of treadmill walking (55–60% peak O2 uptake) during the evening, 12 h before a 4-h standardized mixed meal test. Frequent blood samples were taken and analyzed for acylated ghrelin, and a visual analog scale was used to assess perceived hunger and fullness. In NW individuals, EX, compared with NoEX, reduced fasting acylated ghrelin concentrations by 18% ( P = 0.03), and, in response to feeding, the change in acylated ghrelin ( P = 0.02) was attenuated by 39%, but perceived hunger and fullness were unaltered. In Ob individuals, despite no changes in fasting or postprandial acylated ghrelin concentrations with EX, postprandial fullness was attenuated by 46% compared with NoEX ( P = 0.05). In summary, exercise performed the night before a meal suppresses acylated ghrelin concentrations in NW individuals without altering perceived hunger or fullness. In Ob individuals, despite no changes in acylated ghrelin concentrations, EX reduced the fullness response to the test meal. Acylated ghrelin and perceived fullness responses are differently altered by acute aerobic exercise in NW and Ob individuals.

Effects of intraduodenal lipid and protein on gut motility and hormone release, glycemia, appetite, and energy intake in lean men

BACKGROUND

Intraduodenal lipid modulates gastrointestinal motility and hormone release and suppresses energy intake (EI) more than does intraduodenal glucose. Oral protein is the most satiating macronutrient and modulates postprandial glycemia; the comparative effects of intraduodenal protein and lipid and their combined effects are unclear.

OBJECTIVE

We investigated the effects of intraduodenal protein and lipid, alone or in combination, on antropyloroduodenal motility, gastrointestinal hormone release, glycemia, and EI.

DESIGN

Twenty lean men were studied on 5 randomized, double-blind occasions. Antropyloroduodenal motility, cholecystokinin, glucagon-like peptide-1 (GLP-1), insulin, glucagon, blood glucose, appetite, and nausea were measured during 90-min isocaloric (3 kcal/min) intraduodenal infusions of lipid [pure lipid condition (L3)], protein [pure protein condition (P3)], a 2:1 combination of lipid and protein [2:1 lipid:protein condition (L2P1)], a 1:2 combination of lipid and protein [1:2 lipid:protein condition (L1P2)], or a control. Immediately after the infusion, EI from a buffet lunch was quantified.

RESULTS

In comparison with the control, all nutrient infusions suppressed antral and duodenal and stimulated pyloric pressures (P < 0.05). Cholecystokinin and GLP-1 release and pyloric stimulation were lipid-load dependent (r ≥ 0.39, P < 0.01), insulin and glucagon releases were protein-load dependent (r = 0.83, P < 0.001), and normoglycemia was maintained. L3 but not P3 increased nausea (P < 0.05). Compared with the control, L3 and P3 but not L2P1 or L1P2 suppressed EI (P < 0.05) without major effects on appetite.

CONCLUSIONS

In lean men, despite differing effects on gut function, intraduodenal lipid and protein produce comparable reductions in energy intake. The effects of lipid may be a result of nausea. Protein also regulates blood glucose by stimulating insulin and glucagon. In contrast, at the loads selected, lipid:protein combinations did not suppress energy intake, suggesting that a threshold load is required to elicit effects. This trial was registered at Australia and New Zealand Clinical Trial Registry (http://www.anzctr.org.au) as 12609000949280.

Effects of rectal administration of taurocholic acid on glucagon-like peptide-1 and peptide YY secretion in healthy humans

Glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), secreted by enteroendocrine L-cells located most densely in the colon and rectum, are of fundamental importance in blood glucose and appetite regulation. In animal models, colonic administration of bile acids can stimulate GLP-1 and PYY by TGR5 receptor activation. We evaluated the effects of taurocholic acid (TCA), administered as an enema, on plasma GLP-1 and PYY, as well as gastrointestinal sensations in 10 healthy male subjects, and observed that rectal administration of TCA promptly stimulated secretion of both GLP-1 and PYY, and increased fullness, in a dose-dependent manner. These observations confirm that topical application of bile acids to the distal gut may have potential for the management of type 2 diabetes and obesity.

Liquid meal composition, postprandial satiety hormones, and perceived appetite and satiety in obese women during acute caloric restriction

OBJECTIVE

The purpose of this study was to compare postprandial satiety regulating hormone responses (pancreatic polypeptide (PP) and peptide tyrosine tyrosine (PYY)) and visual analog scale- (VAS) assessed perceived appetite and satiety between liquid high-protein (HP) and high-carbohydrate (HC) meals in obese women during acute (24-h) caloric restriction.

DESIGN

Eleven obese premenopausal women completed two conditions in random order in which they consumed 1500 calories as six 250-calorie HP meals or six 250-calorie HC meals over a 12-h period. Blood samples were taken at baseline and every 20 min thereafter and analyzed for PP and PYY concentrations. At these same points, perceived hunger and fullness were assessed with a VAS. The incremental area under the curve (iAUC) was used to compare postprandial responses.

RESULTS

The 12-h PP and PYY iAUC were greater (P≤0.05) during the HP condition (PP: 4727±1306 pg/ml×12 h, PYY: 1373±357 pg/ml×12 h) compared with the HC condition (PP: 2300±528 pg/ml×12 h, PYY: 754±246 pg/ml×12 h). Perceived hunger and fullness were not different between conditions (P>0.05). The greatest changes in PYY and perceived fullness occurred after the morning meals during both conditions.

CONCLUSIONS

These data suggest that in obese women during acute caloric restriction before weight loss, i) liquid HP meals, compared with HC meals, result in greater postprandial PP and PYY concentrations, an effect not associated with differential appetite or satiety responses, and ii) meal-induced changes in PYY and satiety are greatest during the morning period, regardless of dietary macronutrient composition.

Intraduodenal protein modulates antropyloroduodenal motility, hormone release, glycemia, appetite, and energy intake in lean men

BACKGROUND

Intraduodenal fat and carbohydrate modulate antropyloroduodenal motility and hormone release and suppress appetite and energy intake in a load-dependent manner. Protein also suppresses energy intake, but its effects on these gastrointestinal factors and their role in the appetite-suppressive effects of protein remain unclear.

OBJECTIVE

We aimed to characterize the effects of different intraduodenal protein loads on antropyloroduodenal pressures, gastrointestinal hormone release, glucose and insulin concentrations, appetite perceptions, and energy intake.

DESIGN

Sixteen lean, healthy men were studied on 4 occasions in a randomized, double-blind fashion. Antropyloroduodenal pressures, plasma glucagon-like peptide 1 (GLP-1), cholecystokinin, peptide YY, ghrelin, blood glucose, serum insulin, and appetite were measured during 60-min, 4-mL/min intraduodenal infusions of protein at 0.5, 1.5, or 3 kcal/min or saline (control). Energy intakes at a buffet lunch consumed immediately after the infusion were quantified.

RESULTS

Increases in the load of protein resulted in greater suppression of antral motility, greater stimulation of basal and isolated pyloric pressures and plasma cholecystokinin and GLP-1 concentrations, and greater suppression of energy intake. However, energy intake was reduced only after a protein load of 3 kcal/min compared with after all other treatments (P < 0.05). The suppression of energy intake after adjustment for cholecystokinin, GLP-1, and insulin was related inversely with basal pyloric pressure (r = -0.51, P < 0.001).

CONCLUSION

The acute effects of intraduodenal protein on antropyloroduodenal motility, gastrointestinal hormone release, glucose, and insulin are load dependent and contribute to the suppression of energy intake. This trial was registered at www.anzctr.org.au as 12610000376044.

Effects of fat, protein, and carbohydrate and protein load on appetite, plasma cholecystokinin, peptide YY, and ghrelin, and energy intake in lean and obese men

While protein is regarded as the most satiating macronutrient, many studies have employed test meals that had very high and unsustainable protein contents. Furthermore, the comparative responses between lean and obese subjects and the relationships between energy intake suppression and gut hormone release remain unclear. We evaluated the acute effects of meals with modest variations in 1) fat, protein, and carbohydrate content and 2) protein load on gastrointestinal hormones, appetite, and subsequent energy intake in lean and obese subjects. Sixteen lean and sixteen obese men were studied on four occasions. Following a standardized breakfast, they received for lunch: 1) high-fat (HF), 2) high-protein (HP), 3) high-carbohydrate/low-protein (HC/LP), or 4) adequate-protein (AP) isocaloric test meals. Hunger, fullness, and gut hormones were measured throughout, and at t = 180 min energy intake at a buffet meal was quantified. In lean subjects, hunger was less and fullness greater following HF, HP, and AP compared with HC/LP meals, and energy intake was less following HF and HP compared with HC meals (P < 0.05). In the obese subjects, hunger was less following HP compared with HF, HC/LP, and AP meals, and energy intake was less following HP and AP compared with HF and HC meals (P < 0.05). There were no major differences in hormone responses to the meals among subject groups, but the CCK and ghrelin responses to HP and AP were sustained in both groups. In conclusion, HP meals suppress energy intake in lean and obese subjects, an effect potentially mediated by CCK and ghrelin, while obese individuals appear to be less sensitive to the satiating effects of fat.

Effects of variations in intragastric volume on blood pressure and splanchnic blood flow during intraduodenal glucose infusion in healthy older subjects

The postprandial reduction in blood pressure (BP) is triggered by the interaction of nutrients with the small intestine and associated with an increase in splanchnic blood flow. Gastric distension may attenuate the postprandial fall in BP. The aim of this study was to determine the effects of differences in intragastric volume, including distension at a low (100 ml) volume, on BP and superior mesenteric artery (SMA) blood flow responses to intraduodenal glucose in healthy older subjects. BP and heart rate (HR; automated device), SMA blood flow (Doppler ultrasound), mesenteric vascular resistance (MVR), and plasma norepinephrine of nine male subjects (65-75 yr old) were measured after an overnight fast on 4 separate days in random order. On each day, subjects were intubated with a nasoduodenal catheter, incorporating a duodenal infusion port, and orally with a second catheter, incorporating a barostat bag, positioned in the fundus. Each subject received a 60-min (t = 0-60 min) intraduodenal glucose infusion (3 kcal/min) and gastric distension at a volume of 1) 0 ml (V0), 2) 100 ml (V100), 3) 300 ml (V300), or 4) 500 ml (V500). Systolic BP fell (P < 0.05) during V0, but not during V100, V300, or V500. In contrast, HR (P < 0.01) and SMA blood flow (P < 0.001) increased and MVR decreased (P < 0.05) comparably on all 4 days. Plasma norepinephrine rose (P < 0.01) in response to intraduodenal glucose, with no difference between the four treatments. There was a relationship between the areas under the curve for the change in systolic BP from baseline with intragastric volume (r = 0.60, P < 0.001). In conclusion, low-volume (≤100 ml) gastric distension has the capacity to abolish the fall in BP induced by intraduodenal glucose in healthy older subjects without affecting SMA blood flow or MVR. These observations support the concept that nonnutrient gastric distension prior to a meal has potential therapeutic applications in the management of postprandial hypotension.

Effects of different sweet preloads on incretin hormone secretion, gastric emptying, and postprandial glycemia in healthy humans

BACKGROUND

Macronutrient "preloads" can stimulate glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), slow gastric emptying, and reduce postprandial glycemic excursions. After sweet preloads, these effects may be signaled by sodium-glucose cotransporter-1 (SGLT1), sweet taste receptors, or both.

OBJECTIVE

We determined the effects of 4 sweet preloads on GIP and GLP-1 release, gastric emptying, and postprandial glycemia.

DESIGN

Ten healthy subjects were studied on 4 separate occasions each. A preload drink containing 40 g glucose, 40 g tagatose/isomalt mixture (TIM), 40 g 3-O-methylglucose (3OMG; a nonmetabolized substrate of SGLT1), or 60 mg sucralose was consumed 15 min before a (13)C-octanoic acid-labeled mashed potato meal. Blood glucose, plasma total GLP-1 and GIP, serum insulin, and gastric emptying were determined.

RESULTS

Both glucose and 3OMG stimulated GLP-1 and GIP release in advance of the meal (each P < 0.05), whereas TIM and sucralose did not. The overall postprandial GLP-1 response was greater after glucose, 3OMG, and TIM than after sucralose (P < 0.05), albeit later after TIM than the other preloads. The blood glucose and insulin responses in the first 30 min after the meal were greatest after glucose (each P < 0.05). Gastric emptying was slower after both 3OMG and TIM than after sucralose (each P < 0.05).

CONCLUSIONS

In healthy humans, SGLT1 substrates stimulate GLP-1 and GIP and slow gastric emptying, regardless of whether they are metabolized, whereas the artificial sweetener sucralose does not. Poorly absorbed sweet tastants (TIM), which probably expose a greater length of gut to nutrients, result in delayed GLP-1 secretion but not in delayed GIP release. These observations have the potential to optimize the use of preloads for glycemic control. This trial was registered at www.actr.org.au as ACTRN12611000775910.

Therapeutic potential of ghrelin in restricting-type anorexia nervosa

Anorexia nervosa (AN) is an eating disorder characterized by a decrease in caloric intake and malnutrition. It is associated with a variety of medical morbidities as well as significant mortality. Nutritional support is of paramount importance to prevent impaired quality of life later in life in affected patients. Some patients with restricting-type AN who are fully motivated to gain body weight cannot increase their food intake because of malnutrition-induced gastrointestinal dysfunction. Chronicity of AN prevents participation in social activities and leads to increased medical expenses. Therefore, there is a pressing need for effective appetite-stimulating therapies for patients with AN. Ghrelin is the only orexigenic hormone that can be given intravenously. Intravenous infusion of ghrelin is reported to increase food intake and body weight in healthy subjects as well as in patients with poor nutritional status. Here, we introduce the results of a pilot study that investigated the effects of ghrelin on appetite, energy intake, and nutritional parameters in five patients with restricting-type AN, who are fully motivated to gain body weight but could not increase their food intake because of malnutrition-induced gastrointestinal dysfunction.

Relative Reinforcing Value of Energy-dense Snack Foods: In Overweight and Obese Adults

Purpose: Obese people find energy-dense food more reinforcing than do their non-obese peers, and reinforcement influences food intake. We examined how the degree of adiposity, measured by body mass index (BMI), is associated with the relative reinforcing value of energy-dense snack foods versus fruits and vegetables in overweight and obese people.

Methods: Ninety-two overweight or obese students in introductory psychology courses completed questionnaires on age, sex, BMI, hunger, smoking status, dietary restraint, and hedonic (liking) ratings for energy-dense snack foods and fruits and vegetables. The questionnaire also was used to evaluate the relative reinforcing value of these snack foods in comparison with fruits and vegetables.

Results: The BMI predicted the relative reinforcing value of energy-dense snack food. This positive relationship remained significant after we controlled for age, sex, dietary restraint, hunger, smoking status, and snack food hedonics.

Conclusions: The greater the degree of overweight and obesity, the greater the motivation to obtain energy-dense snack foods. Because the rewarding value of food is a strong determinant of energy intake, a useful approach to preventing and treating obesity may be introducing pharmacological or behavioural nutrition intervention to reduce the rewarding value of energydense snack foods, or increasing the rewarding value of fruits and vegetables.

Rye kernel breakfast increases satiety in the afternoon - an effect of food structure

Background

The structure of whole grain cereals is maintained to varying degrees during processing and preparation of foods. Food structure can influence metabolism, including perceived hunger and satiety. A diet that enhances satiety per calorie may help to prevent excessive calorie intake. The objective of this work was to compare subjective appetite ratings after consumption of intact and milled rye kernels.

Methods

Two studies were performed using a randomized, cross-over design. Ratings for appetite (hunger, satiety and desire to eat) were registered during an 8-h period after consumption of whole and milled rye kernels prepared as breads (study 1, n = 24) and porridges (study 2, n = 20). Sifted wheat bread was used as reference in both study parts and the products were eaten in iso-caloric portions with standardized additional breakfast foods. Breads and porridges were analyzed to determine whether structure (whole vs. milled kernels) effected dietary fibre content and composition after preparation of the products. Statistical evaluation of the appetite ratings after intake of the different breakfasts was done by paired t-tests for morning and afternoon ratings separately, with subjects as random effect and type of breakfast and time points as fixed effects.

Results

All rye breakfasts resulted in higher satiety ratings in the morning and afternoon compared with the iso-caloric reference breakfast with sifted wheat bread. Rye bread with milled or whole kernels affected appetite equally, so no effect of structure was observed. In contrast, after consumption of the rye kernel breakfast, satiety was increased and hunger suppressed in the afternoon compared with the milled rye kernel porridge breakfast. This effect could be related to structural differences alone, because the products were equal in nutritional content including dietary fibre content and composition.

Conclusions

The study demonstrates that small changes in diet composition such as cereal grain structure have the potential to effect feelings of hunger and satiety.

Trial registration

This trial was registered at clinicaltrials.gov as NCT01042418.

Marked differences in gustatory and gastrointestinal sensitivity to oleic acid between lean and obese men

BACKGROUND

Both orosensory stimulation and feedback from the gastrointestinal tract contribute to energy intake regulation.

OBJECTIVE

We evaluated the hypothesis that overweight or obese subjects would be less sensitive to both oral and intraduodenal oleic acid exposure than would lean subjects.

DESIGN

Eleven overweight or obese and 8 lean men were studied on 2 occasions, during which antropyloroduodenal pressures, plasma cholecystokinin and peptide YY, and appetite were measured during 90-min intraduodenal infusions of saline or oleic acid (18:1 load: 0.78 kcal/min); energy intake (buffet lunch) was determined immediately afterward. Oral detection thresholds for 18:1 and recent dietary intake (2-d recall) were also quantified.

RESULTS

In lean subjects, the number of isolated pyloric pressure waves (IPPWs) was greater during 18:1 infusion than during saline infusion (P < 0.05); no significant differences were observed between the 18:1 and saline infusions in the overweight or obese subjects. In both groups, 18:1 stimulated plasma cholecystokinin and peptide YY and suppressed energy intake compared with saline (P < 0.05), with trends for reduced cholecystokinin and energy intake responses in the overweight or obese subjects. Detection thresholds for 18:1 were greater in overweight or obese (7.9 ± 0.1 mmol/L) than in lean (4.1 ± 0.4 mmol/L) subjects (P < 0.05). Overweight or obese subjects had greater recent energy (P < 0.05) and fat (P = 0.07) intakes than did lean subjects. There was a direct relation (r = 0.669) of body mass index with 18:1 detection thresholds and inverse relations (r < -0.51) of IPPWs with body mass index and 18:1 detection thresholds (P < 0.05).

CONCLUSIONS

The ability to detect oleic acid both orally and within the gastrointestinal tract is compromised in obese men, and oral and gastrointestinal responses to oleic acid are related. This trial was registered at www.actr.org.au (Australian New Zealand Clinical Trials Registry) as 12609000557235.

Effects of acute dietary restriction on gut motor, hormone and energy intake responses to duodenal fat in obese men

BACKGROUND

Previous patterns of energy intake influence gastrointestinal function and appetite, probably reflecting changes in small-intestinal nutrient-mediated feedback. Obese individuals consume more fat and may be less sensitive to its gastrointestinal and appetite-suppressant effects than lean individuals.

OBJECTIVE

To evaluate the hypothesis that, in obese individuals, the effects of duodenal fat on gastrointestinal motor and hormone function, and appetite would be enhanced by a short period on a very-low-calorie diet (VLCD).

METHODS

Eight obese men (body mass index 34±0.6  kg  m(-2)) were studied on two occasions, before (V1), and immediately after (V2), a 4-day VLCD. On both occasions, antropyloroduodenal motility, plasma cholecystokinin (CCK), peptide-YY (PYY) and ghrelin concentrations, and appetite perceptions were measured during a 120-min intraduodenal fat infusion (2.86  kcal  min(-1)). Immediately afterwards, energy intake was quantified.

RESULTS

During V2, basal pyloric pressure and the number and amplitude of isolated pyloric pressure waves (PWs) were greater, whereas the number of antral and duodenal PWs was less, compared with V1 (all P<0.05). Moreover, during V2, baseline ghrelin concentration was higher; the stimulation of PYY and suppression of ghrelin by lipid were greater, with no difference in CCK concentration; and hunger and energy intake (kJ; V1: 4378±691, V2: 3634±700) were less (all P<0.05), compared with V1.

CONCLUSIONS

In obese males, the effects of small-intestinal lipid on gastrointestinal motility and some hormone responses and appetite are enhanced after a 4-day VLCD.

Carbohydrate and fat digestion is necessary for maximal suppression of total plasma ghrelin in healthy adults

It is uncertain whether the postprandial suppression of ghrelin is dependent on digestion and absorption of nutrients or whether the presence of nutrients in the small intestine is sufficient. Twenty-four healthy young adults with a mean age of 23 ± 0.6 years were examined on 3 separate days after an overnight fast. Twelve subjects participated in Part A, and the other 12 subjects in Part B. In Part A, subjects consumed, in random order, one of three study drinks: 300 mL water; 300 mL high-fat drink, with and without, 120 mg orlistat. In Part B, subjects received, in random order, one of three drinks: 300 mL water; 300 mL sucrose, with and without, 100mg acarbose. In both parts gastric emptying as measured by 2-D ultrasound. In Part A, plasma ghrelin concentrations decreased following ingestion of the high-fat drink, but did not change with the high-fat-orlistat drink or water. In Part B, the suppression of plasma ghrelin following the sucrose drink, was attenuated by acarbose. Orlistat accelerated gastric emptying of the high-fat drink, while acarbose delayed gastric emptying of the sucrose drink. In conclusion, fat and carbohydrate digestion is required for maximal suppression of ghrelin secretion.

Effects of nutritional supplementation on the appetite and energy intake responses to IV cholecystokinin in older adults

Human aging is associated with a reduction in appetite and food intake. Increased activity of the satiety hormone, cholecystokinin (CCK), may be partly responsible. This study aimed to determine whether an increase in fat and energy intake modifies the suppressive effects of CCK-8 on appetite and energy intake. Fourteen healthy older adults completed three separate dietary periods, a 14-day and a 7-day normal diet (ND; 8272 ± 480 kJ/day; 35% fat), and a 14-day high-fat diet (HFD; 11,642 ± 414 kJ/day; 43% fat), in randomised order. Immediately following each diet, subjects received, in single-blinded fashion, a 30-min intravenous infusion of either CCK-8 (1.5 ng/kg/min) (ND-CCK, HFD-CCK) or 0.9% saline (ND-SAL), the latter following only ND. Plasma CCK concentrations, appetite responses and energy intake at a buffet meal were determined. Energy intake at the buffet meal was higher on the ND-SAL study day (3349 ± 224 kJ), when compared with either ND-CCK (3023 ± 317 kJ) or HFD-CCK (2905 ± 316 kJ). The suppression of energy intake by CCK-8 infusion did not differ between the two diets. We conclude that suppression of energy intake by exogenous CCK-8 does not appear to be attenuated by incorporation of supplemental high-energy, high-fat drinks in the diet of healthy older adults.

Changes in plasma levels of ghrelin, leptin, and other hormonal and metabolic parameters following standardized breakfast, lunch, and physical exercise before and after a multidisciplinary weight-reduction intervention in obese adolescents

OBJECTIVE

To investigate in severely obese adolescents the effects of a 3-week multidisciplinary weight-reduction intervention involving moderate energy restriction, individualised physical activity and behavior therapy on the response of some hormonal and metabolic parameters to meals and exercise.

DESIGN

Clinical longitudinal study on inpatients in a specialised institution.

SUBJECTS

A total of 20 obese adolescents (10 boys and 10 girls) aged 12-17 yr [body mass index (BMI): 37.7±6.1 kg/m2; fat mass (FM): 44.8±13.2 kg].

MEASUREMENTS

The changes in plasma concentration of leptin, ghrelin, GH, IGF-I, insulin, glucose, and non-esterified fatty acids (NEFA) in response to standardised meals and exercise bouts were measured before and after the weight-reduction intervention. At the same times, body composition was assessed by bioelectrical impedance as well as appetite sensations using a visual analog scale.

RESULTS

At the end of the intervention, the adolescents had lost body weight and FM (expressed both in kg and %) (p<0.05), without any significant fat-free mass loss (in % terms). In response to both meals and exercise, after the 3-week intervention, plasma leptin concentration decreased significantly (p<0.05), whereas the other hormones (insulin, ghrelin, GH, and IGF-I) and metabolic parameters (glucose and NEFA) did not change. Interestingly, appetite was not affected by the intervention.

CONCLUSION

This 3-week multidisciplinary intervention in obese adolescents induced a significant body weight loss with beneficial changes in body composition. However, despite there being no change in metabolic parameters and ghrelin in response to meals and exercise after the intervention, plasma concentrations of leptin were decreased. The failure of ghrelin levels to increase by this approach might explain the good control of appetite observed at the end of the study.

Metformin increases plasma ghrelin in Type 2 diabetes

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

* Metformin, unlike the other major antihyperglycaemic drugs, is not associated with weight gain. * Ghrelin is an appetite-stimulating hormone whose concentrations vary in relation to food, obesity and diabetes control. * Reports are conflicting about how metformin affects ghrelin concentrations, and this study was aimed at resolving this issue in patients with Type 2 diabetes.

WHAT THIS STUDY ADDS

* In this study an increase in ghrelin concentrations was seen in response to metformin treatment in patients with Type 2 diabetes. * This effect was opposite to what might be expected if the effect of metformin on weight control was mediated via suppression of ghrelin. * It is likely that the ghrelin response was secondary to improved glycaemic control. * Meal time changes in appetite and satiety did not correlate with changes in ghrelin, which suggests ghrelin may not be important in meal initiation.

AIMS

Metformin treatment of Type 2 diabetes is not usually associated with weight gain, and may assist with weight reduction. Plasma ghrelin concentrations are inversely associated with obesity and food intake. Metformin might therefore affect ghrelin concentrations, although previous studies have shown variable results in this regard. The primary aim of this study was to determine the effect of metformin on plasma ghrelin, appetite and satiety in patients with Type 2 diabetes.

METHODS

Eighteen patients with Type 2 diabetes were studied before and after 6 weeks of metformin treatment, which was titrated to 1 g b.d. On the study days patients were fed standard meals of 390 kcal at 08.00 and 12.30 h, plasma samples were collected at 15- and 30-min intervals, and appetite and satiety were measured on visual analogue scales. Changes in the area under the concentration-time curves (AUCs) of plasma ghrelin, insulin, glucose, appetite and satiety were assessed and examined for correlations with metformin AUCs. Changes in fasting adiponectin and leptin were also measured.

RESULTS

Treatment with metformin increased the mean AUC (07.30-16.30 h) of plasma ghrelin by 24% (P= 0.003), while decreasing those of glucose by 19% (P < 0.001) and insulin by 19% (P= 0.001). No changes were detected in hunger and satiety, or in fasting adiponectin or leptin concentrations. There were no clear correlations between metformin plasma concentrations (AUC) and changes in plasma glucose, insulin or ghrelin.

CONCLUSIONS

Treatment of Type 2 diabetes with metformin was associated with increased plasma ghrelin concentrations, without associated changes in hunger and satiety.

Pooled-data analysis identifies pyloric pressures and plasma cholecystokinin concentrations as major determinants of acute energy intake in healthy, lean men

BACKGROUND

The interaction of nutrients with the small intestine modulates gastropyloroduodenal motility, stimulates the release of gut hormones, and suppresses appetite and energy intake.

OBJECTIVE

We evaluated which, if any, of these variables are independent determinants of acute energy intake in healthy, lean men.

DESIGN

We pooled data from 8 published studies that involved a total of 67 healthy, lean men in whom antropyloroduodenal pressures, gastrointestinal hormones, and perceptions were measured during intraduodenal nutrient or intravenous hormone infusions. In all of the studies, the energy intake at a buffet lunch was quantified immediately after the infusions. To select specific motor, hormone, or perception variables for inclusion in a multivariable mixed-effects model for determination of independent predictors of energy intake, we assessed all variables for collinearity and determined within-subject correlations between energy intake and these variables by using bivariate analyses adjusted for repeated measures.

RESULTS

Although correlations were shown between energy intake and antropyloroduodenal pressures, plasma hormone concentrations, and gastrointestinal perceptions, only the peak number of isolated pyloric-pressure waves, peak plasma cholecystokinin concentration, and area under the curve of nausea were identified as independent predictors of energy intake (all P < 0.05), so that increases of 1 pressure wave, 1 pmol/L, and 1 mm . min were associated with reductions in energy intake of approximately 36, approximately 88, and approximately 0.4, respectively.

CONCLUSION

We identified specific changes in gastrointestinal motor and hormone functions (ie, stimulation of pyloric pressures and plasma cholecystokinin) and nausea that are associated with the suppression of acute energy intake.

Polycystic ovary syndrome and weight management

Polycystic ovary syndrome (PCOS) is a common condition in women of reproductive age, and has reproductive, metabolic and psychological implications. Weight gain and obesity worsen the features of PCOS, while weight loss improves the features of PCOS. While there are potential barriers to successful weight management in young women who do not suffer from PCOS, women with PCOS may experience additional barriers. Weight management strategies in younger women with or without PCOS should encompass both the prevention of excess weight gain and achieving and maintaining a reduced weight through multidisciplinary lifestyle management, comprising dietary, exercise and behavioral therapy, as well as attention to psychosocial stress and practical and physiological barriers to weight management. Further research is warranted in the examination of specific barriers to weight management in women with PCOS, as well as in the determination of optimal components of lifestyle weight management interventions in young women in order to facilitate long-term compliance.

Appetite control: methodological aspects of the evaluation of foods

This report describes a set of scientific procedures used to assess the impact of foods and food ingredients on the expression of appetite (psychological and behavioural). An overarching priority has been to enable potential evaluators of health claims about foods to identify justified claims and to exclude claims that are not supported by scientific evidence for the effect cited. This priority follows precisely from the principles set down in the PASSCLAIM report. The report allows the evaluation of the strength of health claims, about the effects of foods on appetite, which can be sustained on the basis of the commonly used scientific designs and experimental procedures. The report includes different designs for assessing effects on satiation as opposed to satiety, detailed coverage of the extent to which a change in hunger can stand alone as a measure of appetite control and an extensive discussion of the statistical procedures appropriate for handling data in this field of research. Because research in this area is continually evolving, new improved methodologies may emerge over time and will need to be incorporated into the framework. One main objective of the report has been to produce guidance on good practice in carrying out appetite research, and not to set down a series of commandments that must be followed.

Water consumption increases weight loss during a hypocaloric diet intervention in middle-aged and older adults

Water consumption acutely reduces meal energy intake (EI) among middle-aged and older adults. Our objectives were to determine if premeal water consumption facilitates weight loss among overweight/obese middle-aged and older adults, and to determine if the ability of premeal water consumption to reduce meal EI is sustained after a 12-week period of increased water consumption. Adults (n = 48; 55-75 years, BMI 25-40 kg/m(2)) were assigned to one of two groups: (i) hypocaloric diet + 500 ml water prior to each daily meal (water group), or (ii) hypocaloric diet alone (nonwater group). At baseline and week 12, each participant underwent two ad libitum test meals: (i) no preload (NP), and (ii) 500 ml water preload (WP). Meal EI was assessed at each test meal and body weight was assessed weekly for 12 weeks. Weight loss was ~2 kg greater in the water group than in the nonwater group, and the water group (beta = -0.87, P < 0.001) showed a 44% greater decline in weight over the 12 weeks than the nonwater group (beta = -0.60, P < 0.001). Test meal EI was lower in the WP than NP condition at baseline, but not at week 12 (baseline: WP 498 +/- 25 kcal, NP 541 +/- 27 kcal, P = 0.009; 12-week: WP 480 +/- 25 kcal, NP 506 +/- 25 kcal, P = 0.069). Thus, when combined with a hypocaloric diet, consuming 500 ml water prior to each main meal leads to greater weight loss than a hypocaloric diet alone in middle-aged and older adults. This may be due in part to an acute reduction in meal EI following water ingestion.

Impaired postprandial response of active ghrelin and prolonged suppression of hunger sensation in the elderly

BACKGROUND

The role of the orexigenic hormone ghrelin is of major interest in the altered appetite regulation of the elderly.

METHODS

Basal and postprandial levels of active and total ghrelin were measured in 15 younger (mean age 35.4 years) and 19 older (80.7 years) participants following a carbohydrate-rich test meal.

RESULTS

Our results showed that older participants felt postprandially less hungry and more full. Although basal levels were not significantly different, active and total ghrelin levels declined postprandially only in the younger study participants. Highly significant differences between the two age groups were shown for the changes of the area under the curve for active ghrelin (p = .024).

CONCLUSIONS

Our study demonstrates for the first time that differences in hunger and satiety sensations in relation to age are paralleled by a substantially different response of acylated and total ghrelin, that is, the absence of a postprandial decline in ghrelin levels.

Increased carbohydrate induced ghrelin secretion in obese vs. normal-weight adolescent girls

Orexigenic and anorexigenic pathways mediate food intake and may be affected by meal composition. Our objective was to determine whether changes in levels of active ghrelin and peptide YY (PYY) differ in obese vs. normal-weight adolescent girls following specific macronutrient intake and predict hunger and subsequent food intake. We enrolled 26 subjects: 13 obese and 13 normal-weight girls, 12-18 years old, matched for maturity (as assessed by bone age) and race. Subjects were assigned a high-carbohydrate, high-protein, and high-fat breakfast in random order. Active ghrelin and PYY were assessed for 4 h after breakfast and 1 h after intake of a standardized lunch. Hunger was assessed using a standardized visual analog scale (VAS). No suppression in active ghrelin levels was noted following macronutrient intake in obese or normal-weight girls. Contrary to expectations, active ghrelin increased in obese girls following the high-carbohydrate breakfast, and the percent increase was higher than in controls (P = 0.046). Subsequent food intake at lunch was also higher (P = 0.03). Following the high-fat breakfast, but not other breakfasts, percent increase in PYY was lower (P = 0.01) and subsequent lunch intake higher (P = 0.005) in obese compared with normal-weight girls. In obese adolescents, specific intake of high-carbohydrate and high-fat breakfasts is associated with greater increases in ghrelin, lesser increases in PYY, and higher intake at a subsequent meal than in controls. Changes in anorexigenic and orexigenic hormones in obese vs. normal-weight adolescents following high-carbohydrate and high-fat meals may influence hunger and satiety signals and subsequent food intake.

Effects of the phases of the menstrual cycle on gastric emptying, glycemia, plasma GLP-1 and insulin, and energy intake in healthy lean women

There is evidence that the menstrual cycle affects appetite, such that energy intake is lower during the follicular compared with the luteal phase. Gastric emptying influences energy intake, glycemia, and plasma glucagon-like peptide-1 (GLP-1), insulin, and cholecystokinin (CCK) release. We hypothesized that 1) gastric emptying of a glucose drink is slower, and glycemia, plasma hormones, hunger, and energy intake are less, during the follicular compared with the luteal phase; 2) the reduction in the latter parameters during the follicular phase are related to slower gastric emptying; and 3) these parameters are reproducible when assessed twice within a particular phase of the menstrual cycle. Nine healthy, lean women were studied on three separate occasions: twice during the follicular phase (days 6-12) and once during the luteal phase (days 18-24). Following consumption of a 300-ml glucose drink (0.17 g/ml), gastric emptying, blood glucose, plasma hormone concentrations, and hunger were measured for 90 min, after which energy intake at a buffet meal was quantified. During the follicular phase, gastric emptying was slower (P < 0.05), and blood glucose (P < 0.01), plasma GLP-1 and insulin (P < 0.05), hunger (P < 0.01), and energy intake (P < 0.05) were lower compared with the luteal phase, with no differences for CCK or between the two follicular phase visits. There were inverse relationships between energy intake, blood glucose, and plasma GLP-1 and insulin concentrations with the amount of glucose drink remaining in the stomach at t = 90 min (r < -0.6, P < 0.05). In conclusion, in healthy women 1) gastric emptying of glucose is slower, and glycemia, plasma GLP-1 and insulin, hunger, and energy intake are less during the follicular compared with the luteal phase; 2) energy intake, glycemia, and plasma GLP-1 and insulin are related to gastric emptying; and 3) these parameters are reproducible when assessed twice during the follicular phase.

Effect of calorie restriction on subjective ratings of appetite

BACKGROUND

Energy or calorie restriction (CR) has consistently been shown to produce weight loss and have beneficial health effects in numerous species, including primates and humans. Most individuals, however, are unable to sustain weight losses induced through reductions in energy intake, potentially due to increased hunger levels. The effects that prolonged CR has on subjective aspects of appetite have not been well studied. Thus, the present study tested the effect of 6 months of caloric restriction on appetite in healthy, overweight men and women.

METHODS

Forty-eight overweight men and women with a body mass index (BMI; kg m(-2)) between 25-29.9 took part in a 6-month study and were randomised into one of four groups: healthy diet (control); 25% CR; 12.5% CR plus exercise (12.5% increased energy expenditure; CR + EX); low-calorie diet [LCD; 3724 kJ day(-1) (890 kcal day(-1)) until 15% of initial body weight was lost, then maintenance]. Appetite markers (i.e. hunger, fullness, desire to eat, etc.) were assessed weekly during a fasting state.

RESULTS

Body weight was significantly reduced in all three energy-restricted groups (CR = -10.4 +/- 0.9%; CR + EX = -10.0 +/- 0.8%; and LCD = -13.9 +/-0.7%), indicating that participants were adherent to their energy restriction regimen, whereas the healthy diet control group remained weight stable (control = -1.0 +/- 1.1%). Despite these significant weight losses, appetite ratings of participants in the three energy-restricted groups at month 6 were similar to the weight stable control group.

CONCLUSIONS

CR regimens with low fat diets producing significant weight losses have similar effects on appetite markers over a 6-month time period compared to a weight stable control group.

Sweetness and bitterness taste of meals per se does not mediate gastric emptying in humans

In cell line and animal models, sweet and bitter tastants induce secretion of signaling peptides (e.g., glucagon-like peptide-1 and cholecystokinin) and slow gastric emptying (GE). Whether human GE and appetite responses are regulated by the sweetness or bitterness per se of ingested food is, however, unknown. We aimed to determine whether intragastric infusion of "equisweet" (Study A) or "equibitter" (Study B) solutions slow GE to the same extent, and whether a glucose solution made sweeter by the addition of saccharin will slow GE more potently than glucose alone. Healthy nonobese subjects were studied in a single-blind, randomized fashion. Subjects received 500-ml intragastric infusions of predetermined equisweet solutions of glucose (560 mosmol/kgH(2)O), fructose (290 mosmol/kgH(2)O), aspartame (200 mg), and saccharin (50 mg); twice as sweet glucose + saccharin, water (volumetric control) (Study A); or equibitter solutions of quinine (0.198 mM), naringin (1 mM), or water (Study B). GE was evaluated using a [(13)C]acetate breath test, and hunger and fullness were scored using visual analog scales. In Study A, equisweet solutions did not empty similarly. Fructose, aspartame, and saccharin did not slow GE compared with water, but glucose did (P < 0.05). There was no additional effect of the sweeter glucose + saccharin solution (P > 0.05, compared with glucose alone). In Study B, neither bitter tastant slowed GE compared with water. None of the solutions modulated perceptions of hunger or fullness. We conclude that, in humans, the presence of sweetness and bitterness taste per se in ingested solutions does not appear to signal to influence GE or appetite perceptions.

The droplet size of intraduodenal fat emulsions influences antropyloroduodenal motility, hormone release, and appetite in healthy males

BACKGROUND

The presence of fat in the small intestine modulates gastrointestinal motility, stimulates plasma cholecystokinin and peptide YY release, and suppresses appetite and energy intake. These effects are dependent on the lipolysis of fat.

OBJECTIVE

Our aim was to evaluate the hypothesis that increasing the droplet size of a fat emulsion would attenuate these effects.

DESIGN

Ten healthy, lean males were studied on 4 separate occasions in single-blind randomized order. Antropyloroduodenal pressures, plasma triglycerides, cholecystokinin, peptide YY, and appetite were measured during 120-min intraduodenal infusions of fat emulsions comprising 3 different droplet sizes: 1) 0.26 microm (LE-0.26), 2) 30 microm (LE-30), and 3) 170 microm (LE-170) in addition to saline (control). Energy intake at a buffet lunch was quantified immediately after the infusions.

RESULTS

Increasing the droplet size of the lipid emulsion was associated with diminished suppression of antral (r = 0.75, P < 0.01) and duodenal (r = 0.80, P < 0.01) pressure waves and with stimulation of isolated (r = -0.72, P < 0.01) and basal (r = -0.83, P < 0.01) pyloric pressures. Increasing the droplet size was also associated with attenuation of the stimulation of plasma triglycerides (r = -0.73, P < 0.001), cholecystokinin (r = -0.73, P < 0.001), and peptide YY (r = -0.83, P < 0.001) as well as with reductions in the suppression of hunger (r = 0.75, P < 0.01) and energy intake (r = 0.66, P < 0.001).

CONCLUSIONS

The acute effects of intraduodenal fat emulsions on gastrointestinal function and appetite are dependent on fat droplet size. These observations have implications for the design of functional foods to maximize effects on those gut functions that are involved in the suppression of appetite.

Reproducibility of energy intake, gastric emptying, blood glucose, plasma insulin and cholecystokinin responses in healthy young males

Gastric emptying, as well as intragastric meal distribution, and gastrointestinal hormones, including cholecystokinin (CCK), play an important role in appetite regulation. The evaluation of gastrointestinal factors regulating food intake is commonly performed in healthy, lean, young male participants. It has, however, been suggested that there is a marked interindividual variability in the effects of nutrient 'preloads' on energy intake in this group. Whether there is significant intraindividual variation in acute energy intake after a nutrient preload, and, if so, how this relates to day-to-day differences in gastric emptying and gastrointestinal hormone release, is unclear. The purpose of the present paper is to evaluate the hypothesis that energy intake after a nutrient preload would be reproducible and associated with reproducible patterns of gastric emptying, intragastric distribution and gastrointestinal hormone release. Fifteen healthy men (age 25 (sem 5) years) consumed a glucose preload (50 g glucose in 300 ml water; 815 kJ) on three occasions. Gastric emptying and intragastric meal distribution (using three-dimensional ultrasound), blood glucose, plasma insulin and CCK concentrations and appetite perceptions were evaluated over 90 min, and energy intake from a cold buffet-style meal was then quantified. Energy intake was highly reproducible within individuals between visits (intraclass correlation coefficient, ri = 0.9). Gastric emptying, intragastric meal distribution, blood glucose, plasma insulin and CCK concentrations and appetite perceptions did not differ between visits (ri>0.7 for all). In healthy males, energy intake is highly reproducible, at least in the short term, and is associated with reproducible patterns of gastric emptying, glycaemia, insulinaemia and CCK release.

Effects of varying combinations of intraduodenal lipid and carbohydrate on antropyloroduodenal motility, hormone release, and appetite in healthy males

Intraduodenal infusions of both lipid and glucose modulate antropyloroduodenal motility and stimulate plasma CCK, with lipid being more potent than glucose. Both stimulate glucagon-like peptide-1, but only lipid stimulates peptide YY (PYY), while only glucose raises blood glucose and stimulates insulin. When administered in combination, lipid and carbohydrate may, thus, have additive effects on energy intake. However, elevated blood glucose levels do not suppress energy intake, and the effect of insulin is controversial. We hypothesized that increasing the ratio of maltodextrin, a complex carbohydrate, relative to lipid would be associated with a reduction in effects on antropyloroduodenal pressures, gut hormones, appetite, and energy intake, when compared with lipid alone. Ten healthy males were studied on three occasions in double-blind, randomized order. Antropyloroduodenal pressures, plasma CCK, PYY and insulin, blood glucose, and appetite were measured during 90-min intraduodenal infusions of 1) 3 kcal/min lipid (L3), 2) 2 kcal/min lipid and 1 kcal/min maltodextrin (L2/CHO1), or 3) 1 kcal/min lipid and 2 kcal/min maltodextrin (L1/CHO2). Energy intake at a buffet lunch consumed immediately after the infusion was quantified. Reducing the lipid (thus, increasing the carbohydrate) content of the infusion was associated with reduced stimulation of basal pyloric pressures (r = 0.76, P < 0.01), plasma CCK (r = 0.66, P < 0.01), and PYY (r = 0.98, P < 0.001), and reduced suppression of antral (r = -0.64, P < 0.05) and duodenal (r = -0.69, P < 0.05) pressure waves, desire-to-eat (r = -0.8, P < 0.001), and energy intake (r = 0.74, P < 0.01), with no differences in phasic (isolated) pyloric pressures. In conclusion, in healthy males, intraduodenal lipid is a more potent modulator of gut function, associated with greater suppression of energy intake, when compared with isocaloric combinations of lipid and maltodextrin.

Effects of intraluminal local anesthetic on upper gastrointestinal motor, sensory, and peptide hormone responses to intraduodenal glucose

OBJECTIVE

Enterally administered glucose modifies gut sensation, diminishes hunger, and slows gastric emptying by suppressing antral motility and stimulating pyloric pressures. We aimed to clarify the mechanism of small intestinal glucose sensing.

METHODS

We studied eight healthy males twice, in random order. An antroduodenal manometry catheter was positioned with a sleeve sensor across the pylorus. Benzocaine, or vehicle alone, was given into the proximal duodenum as a bolus, followed by continuous infusion for 105 min (T=-15 to 90 min). Glucose was also infused into the proximal duodenum at 3 kcal/min for 90 min (T=0-90 min). Sensations of hunger, bloating, and nausea were assessed with visual analog questionnaires, blood was sampled at intervals, and energy intake at a buffet meal (T=90-120 min) was measured.

RESULTS

Perceptions of bloating and nausea were markedly less with benzocaine when compared with vehicle (P<0.05 for each), with no difference in hunger, or energy intake. In contrast, the suppression of antral waves and stimulation of phasic and tonic pyloric pressures, duodenal waves, and propagated duodenal wave sequences by intraduodenal glucose infusion did not differ between the 2 days. No difference in blood glucose, plasma insulin, or plasma glucagon-like peptide 1 between benzocaine and control was observed, whereas glucose-dependent insulinotropic polypeptide and cholecystokinin concentrations were slightly higher with benzocaine (P<0.05 for both).

CONCLUSION

Mucosal anesthesia ameliorates unpleasant sensations induced by enteral glucose, but does not inhibit the release of gut peptides that feed back on appetite and gastroduodenal motility.

Ghrelin increases hunger and food intake in patients with restricting-type anorexia nervosa: a pilot study

Ghrelin increases hunger sensation and food intake in various patients with appetite loss. Anorexia nervosa (AN) begins with psychological stress-induced anorexia and some patients cannot increase their food intake partly because of malnutrition-induced gastrointestinal dysfunction. The effects of ghrelin on appetite, food intake and nutritional parameters in anorexia nervosa (AN) patients were examined. Five female restricting- type AN patients (age: 14-35 y; body mass index: 10.2-14.6 kg/m(2)) had persistently complained of gastrointestinal symptoms and failed to increase body weight. They were hospitalized for 26 days (6 days' pretreatment, 14 days' ghrelin-treatment, and 6 days' post-treatment) and received an intravenous infusion of 3 microg/kg ghrelin twice a day. Ghrelin infusion improved epigastric discomfort or constipation in 4 patients, whose hunger scores evaluated by visual analogue scale questionnaires also increased significantly after ghrelin infusion. Daily energy intake during ghrelin infusion increased by 12-36 % compared with the pre-treatment period. Serum levels of total protein and triglyceride as nutritional parameters significantly increased after ghrelin treatment. There were no serious adverse effects including psychological symptoms. We found that ghrelin decreases gastrointestinal symptoms and increases hunger sensation and daily energy intake without serious adverse events in AN patients. Although the present study had major limitations of the lack of a randomized, placebo-controlled group, non-blindness of the investigators and the small number of patients recruited, it would contribute to further investigations for therapeutic potential of ghrelin in AN patients.

Effects of dietary restraint and body mass index on the relative reinforcing value of snack food

The present study examined the independent and interactive association between dietary restraint, body mass index (BMI) and the relative reinforcing value of food. Four hundred and three introductory psychology students completed questionnaires assessing age, gender, BMI, hunger, smoking status, nicotine dependence, dietary restraint, hedonic ratings for snack food and fruits and vegetables and the relative reinforcing value of snack food and fruits and vegetables. In the overall sample, results indicated a dietary restraint x BMI interaction after controlling for age, hunger, nicotine dependence, and hedonics. However, when regression models were separated by gender, the BMI x restraint interaction emerged only for females and not for males. Findings suggest that BMI moderates the relationship between dietary restraint and snack food reinforcement in females only, such that restraint and snack food reinforcement are inversely correlated in females with lower BMI, but restraint is positively correlated with snack food reinforcement in females with higher BMI. Theoretical and clinical implications of these findings are discussed.

Dose-dependent effects of cholecystokinin-8 on antropyloroduodenal motility, gastrointestinal hormones, appetite, and energy intake in healthy men

CCK mediates the effects of nutrients on gastrointestinal motility and appetite. Intravenously administered CCK stimulates pyloric pressures, increases plasma PYY, and suppresses ghrelin, all of which may be important in the regulation of appetite and energy intake. The dose-related effects of exogenous CCK on gastrointestinal motility and gut hormone release, and the relationships between these effects and those on energy intake, are uncertain. We hypothesized that 1) intravenous CCK-8 would have dose-dependent effects on antropyloroduodenal (APD) pressures, plasma PYY and ghrelin concentrations, appetite, and energy intake and 2) the suppression of energy intake by CCK-8 would be related to the stimulation of pyloric motility. Ten healthy men (age 26 +/- 2 yr) were studied on four separate occasions in double-blind, randomized fashion. APD pressures, plasma PYY and ghrelin, and appetite were measured during 120-min intravenous infusions of 1) saline ("control") or 2) CCK-8 at 0.33 ("CCK0.33"), 3) 0.66 ("CCK0.66"), or 4) 2.0 ("CCK2.0") ng.kg(-1).min(-1). After 90 min, energy intake at a buffet meal was quantified. CCK-8 dose-dependently stimulated phasic and tonic pyloric pressures and plasma PYY concentrations (r > 0.70, P < 0.05) and reduced desire to eat and energy intake (r > -0.60, P < 0.05) without inducing nausea. There were relationships between basal pyloric pressure and isolated pyloric pressure waves (IPPW) with plasma CCK (r > 0.50, P < 0.01) and between energy intake with IPPW (r = -0.70, P < 0.05). Therefore, our study demonstrates that exogenous CCK-8 has dose-related effects on APD motility, plasma PYY, desire to eat, and energy intake and suggests that the suppression of energy intake is related to the stimulation of IPPW.

Assessment of subjective appetite sensations in hemodialysis patients. Agreement and feasibility between traditional paper and pen and a novel electronic appetite rating system

The aim of this study was to assess the agreement between a novel Electronic Appetite Rating System (EARS) and traditional paper and pen visual analog scales (VASs) in a clinical population. 28 hemodialysis patients (mean age 61+/-17 years, 50% male, median dialysis vintage 19.5(4-101) months) were asked to rate their subjective sensations of hunger, fullness and desire to eat on VAS using both methods. The mean (S.D.) bias ranged from 2.6(16.6)mm to 6.2(15.7)mm which indicated that the two methods did not agree. Patients preferred the paper and pen method compared with the EARS. Either method would be suitable to use in a clinical population; however, it would be inappropriate to use the methods interchangeably.

Effect of a cellulose-containing weight-loss supplement on gastric emptying and sensory functions

CM3, a highly cross-linked cellulose in capsule form, expands in the stomach to a size several fold of its original volume. It is purported to induce a prolonged feeling of satiation and a delay in gastric emptying, thus promoting weight loss. We examined whether CM3 delays gastric emptying (using the stable isotope (13)C-octanoic breath test) and whether it influences subjective feelings of appetite sensations (using visual analog scales, VASs). We performed a double-blind randomized placebo-controlled crossover trial in 19 moderately obese but otherwise healthy subjects (mean age 55 +/- 9 years, BMI 31.1 +/- 4.6 kg/m(2)). The subjects were treated with six capsules of CM3 or matching placebo 30 min before a standardized solid meal. Breath collection and VASs were performed over 4 h every 15 min and 30 min, respectively. Half-excretion time of (13)CO(2) in breath, indicating gastric emptying half time, was the primary outcome parameter. The study was powered to detect a change in gastric emptying of 20-30 min. Mean (13)CO(2) half-excretion time changed from 2.3 +/- 0.4 to 2.4 +/- 0.33 h (mean difference +6 min, 95% confidence interval (CI) -3 to +15 min; P = 0.17). Appetite sensations (hunger, satiation, fullness, prospective food consumption, desire to eat something sweet, salty, savory, or fatty) changed over time during the course of the postprandial phase but were not influenced by CM3 (repeated measures ANOVA). In obese subjects, acute administration of the weight-loss supplement CM3 does not delay gastric emptying and does not influence subjective appetite sensations.

Functional dyspepsia is associated with a greater symptomatic response to fat but not carbohydrate, increased fasting and postprandial CCK, and diminished PYY

BACKGROUND/OBJECTIVES

In patients with functional dyspepsia (FD), symptoms are frequently triggered, or exacerbated, by fatty foods. We hypothesized that in FD patients, a high-fat (high-FAT) meal would induce more symptoms than a high-carbohydrate (high-CHO) meal, associated with an altered secretion of cholecystokinin (CCK), peptide-YY (PYY), and ghrelin and an increased antral size, when compared to healthy subjects (HS).

METHODS

FD symptoms, appetite perceptions, plasma hormones, and antral area were measured in 8 FD patients and 8 HS on three separate days after the ingestion of high-CHO or high-FAT (500 kcal/400 g) meals, or a low-nutrient control (180 kcal/400 g); the energy intake was quantified 60 min later.

RESULTS

Nausea (P < 0.01) and pain (P= 0.05) were greater in FD after the high-FAT, when compared to high-CHO and control meals and in HS. Discomfort was greater after all meals in FD when compared to HS (P < 0.05). Fasting CCK and stimulation of CCK by the high-FAT (P < 0.01) meal were greater in FD, while fasting and postprandial PYY were lower (P < 0.001) in FD than in HS, with no differences in fasting, or postprandial, plasma ghrelin between FD and HS. Fasting antral area was greater in FD (P < 0.05), with no differences postprandially between FD and HS. There were no differences in the energy intake between the two groups.

CONCLUSIONS

In FD patients: (a) a high-FAT meal induces more symptoms than an isocaloric high-CHO meal, and (b) fasting and postprandial plasma CCK concentrations are greater and PYY concentrations are less. Our findings have important implications for the development of diet-based therapies for the treatment of FD.

Increased dietary protein consumed at breakfast leads to an initial and sustained feeling of fullness during energy restriction compared to other meal times

The objective of the study was to assess whether the timing of increased dietary protein throughout the day influences the feelings of fullness during energy balance (EB) and restriction (ER). Nine men (age 48 (sem 6) years; BMI 32·7 (sem 0·7) kg/m2) randomly completed five controlled feeding trials, each consisting of 3 d of EB, followed by 3 d of ER of a 3138 kJ/d (750 kcal/d) reduction). The diet was composed of a normal amount of protein (NP) (0·8 g protein/kg per d), or an additional amount of protein (HP) (+0·6 g protein/kg per d) given at breakfast (HP-B), lunch (HP-L), dinner (HP-D) or equally divided among all meals (HP-E). Meal-related (3 h postprandial) and overall (15 h composite) feelings of fullness were assessed from thirteen-point, numbered, linear category scale questionnaires (reported as arbitrary units (au)). When comparing HP treatments, the data are presented as difference from NP. No differences in meal-related or overall fullness were observed among HP treatments during EB. During ER, the HP-B led to greater meal-related fullness (+137 (sem 44) au × 180 min) compared to HP-D ( − 1 (sem 37) au × 180 min; P = 0·003), but not for HP-L (+62 (sem 53) au × 180 min; P = 0·188) or HP-E-B (+92 (sem 85) au × 180 min; P = 0·587). HP-B also led to greater overall (15 h) fullness (+404 (sem 162) au × 900 min) v. HP-L (+33 (sem 162) au × 900 min; P = 0·009) and HP-D ( − 60 (sem 132) au × 900 min; P = 0·05), but not HP-E (+274 (sem 165) au × 900 min; P = 0·188). The initial and sustained feelings of fullness following protein consumption at breakfast suggests that the timing of protein intake differentially influences satiety during ER.

Ileal brake: a sensible food target for appetite control. A review

With the rising prevalence of obesity and related health problems increases, there is increased interest in the gastrointestinal system as a possible target for pharmacological or food-based approaches to weight management. Recent studies have shown that under normal physiological situations undigested nutrients can reach the ileum, and induce activation of the so-called "ileal brake", a combination of effects influencing digestive process and ingestive behaviour. The relevance of the ileal brake as a potential target for weight management is based on several findings: First, activation of the ileal brake has been shown to reduce food intake and increase satiety levels. Second, surgical procedures that increase exposure of the ileum to nutrients produce weight loss and improved glycaemic control. Third, the appetite-reducing effect of chronic ileal brake activation appears to be maintained over time. Together, this evidence suggests that activation of the ileal brake is an excellent long-term target to achieve sustainable reductions in food intake. This review addresses the role of the ileal brake in gut function, and considers the possible involvement of several peptide hormone mediators. Attention is given to the ability of macronutrients to activate the ileal brake, and particularly variation attributable to the physicochemical properties of fats. The emphasis is on implications of ileal brake stimulation on food intake and satiety, accompanied by evidence of effects on glycaemic control and weight loss.

Serum levels of tumour necrosis factor-alpha and interleukin-6 and their correlation with body mass index, weight loss, appetite and survival rate--preliminary data of Viennese outpatients with metastatic cancer during palliative chemotherapy

The serum cytokine levels (in particular interleukine-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha)) of 61 advanced stage cancer patients receiving palliative chemotherapy as outpatients were determined with quantikine immunoassays. The values were correlated with body mass index (BMI), weight loss and appetite. Furthermore cytokine levels of patients who have died within one year were compared with those of patients who have survived more than a year. Serum levels of IL-6 (median: 1.93 pg/ml, range: 0.32-42.87) and of TNF-alpha (median: 2.55 pg/ml, range: 1.03-34.06) did not correlate with BMI, weight loss and appetite. Serum IL-6 levels of patients with survival time less than one year were significantly higher than the levels of patients who survived more than one year, no significant differences in TNF-alpha serum levels were evident. The data of this observation are consistent with current literature. Due to changes in serum levels of proinflammatory cytokines in response to chemotherapy and additional therapy, it is unlikely that IL-6 and TNF-alpha can be used as independent indicators for weight loss and appetite. Nevertheless, high serum levels of IL-6 correlate with short-time mortality.