Meal Timing and Macronutrient Composition Modulate Human Metabolism and Reward-Related Drive to Eat

The ‘time-of-day’ modifies the metabolic response to meals, but less data exist on the diurnal variations in the hedonic drive to eat. In the present paper, we evaluate the effects of meal timing and macronutrient composition on metabolic responses and the homeostatic vs. hedonic regulation of appetite. In study 1, 84 young, healthy adults completed an online computer-based task assessing the homeostatic and hedonic drive to eat in the morning and evening. In study 2, 24 healthy, young men received 2 identical (850 kcal each) meals in the morning (8:45 h) and evening (18:00 h), of 2 experimental conditions: (i) regular carbohydrate (CH) meals (regular-CH), and (ii) high carbohydrate (high-CH) meals, containing 50 and 80% of energy from CHs, respectively. Serial blood samples were obtained, and the postprandial feelings of hunger, satiety, wanting and liking were assessed. Study 1 revealed a higher hedonic drive to eat in the evening compared to the morning. Study 2 confirmed this diurnal pattern of hedonic appetite regulation and, moreover, showed increased glucose and insulin responses to the evening meal. Postprandial ghrelin and leptin as well as feelings of hunger and satiety were not different between the mealtimes nor between the macronutrient conditions. In line with this, the homeostatic drive to eat was neither affected by the mealtime nor macronutrient composition. Increased the hedonic drive to eat in the evening may represent a vulnerability to palatable food and, thus, energy overconsumption. Together with lower evening glucose tolerance, these findings reflect an adverse metabolic constellation at the end of the day, especially after the ingestion of CH-rich foods.     

Pork, beef and chicken have similar effects on acute satiety and hormonal markers of appetite

The effects of three different meat-containing breakfast meals (pork, beef or chicken) on acute satiety and appetite regulatory hormones were compared using a within-subjects study design. Thirty fasting non-smoking pre-menopausal women attended a research centre on three test days to consume, a meat-containing meal matched in energy (kJ) and protein content, palatability, and appearance. No difference was found between meat groups for either energy intake or macronutrient profile of food consumed at a subsequent ad libitum buffet lunch, or over the rest of the day. Visual Analogue Scale (VAS) ratings for hunger and satiety over an 180 min period did not differ between test meals. After consumption of the test meals, a significant difference was found in PYY response between pork and chicken meals (P=0.027) but not for levels of CCK, ghrelin, insulin or glucose. This study positions pork, beef, and chicken as equal in their effect on satiety and release of appetite-related intestinal hormones and of insulin.     

Food intake and plasma ghrelin response during potato-, rice- and pasta-rich test meals

Objective Complex carbohydrates such as potato, rice and pasta are frequently consumed accompaniments of meat meals and have different effects on satiety, food intake, glucose, and insulin concentrations. The orexigenic gastric hormone ghrelin contributes to feeding regulation and as yet it is unknown whether there is any differential ghrelin response to these starchy food items corresponding to their effects on food intake. Methods In 11 subjects the effect of satiating amounts of potatoes, rice or pasta consumed together with 150g pork steak was examined on hunger/satiety ratings, food intake, plasma insulin, glucose and ghrelin concentrations. Results All meals led to comparable quantities of food intake while energy intake was significantly lower after potatoes. Satiety/hunger ratings were significantly different from basal for the entire 4 h period after rice and pasta meals, while they had returned to basal during the 4th hour after potatoes. After rice and pasta insulin rose significantly for 4 h. Ghrelin decreased during the 2nd and 3rd hour. In contrast potatoes stimulated insulin for the initial 2 h only while ghrelin rose significantly by 120 pg/ml over the 4 h period. A significant correlation was observed between ghrelin and hunger ratings while subsequent second meal food and energy intake did not differ irrespective of the preceding ghrelin concentration. Conclusion Compared to rice and pasta satiating amounts of potatoes coingested with meat result in lower energy intake and postprandial insulin concentrations, which is not counterbalanced during subsequent food intake despite higher ghrelin concentrations. The present data support the concept that ghrelin can affect hunger sensations but not necessarily food and energy intake.     

Glucose and insulin responses in healthy women after intake of composite meals containing cod-, milk-, and soy protein

OBJECTIVE: To evaluate the metabolic effect of three different kinds of dietary proteins as part of composite meals with similar macronutrient composition in healthy subjects. DESIGN: A randomised meal study. SETTING: Metabolic ward. SUBJECTS AND METHODS: In total, 17 healthy women, 30-65 years old, consumed three meals in randomised order. The meals consisted of foodstuffs with similar nutrient composition but different types of protein (cod, cottage cheese, or soy protein isolate). The distribution of energy from protein, fat and carbohydrates was 33, 26, and 41 energy percent, respectively. Total amount of energy was 2300 kJ. Blood samples were drawn for assay of B-glucose, S-insulin, S-free fatty acids, S-triglycerides, and C-peptide in the fasting state and at seven times (20, 40, 60, 90, 120, 180, and 240 min) after starting to eat the test meal. RESULTS: The blood glucose response after the cod protein meal differed from that of the soy protein meal, with a larger area under the curve (AUC) calculated up to 120 min. The serum insulin response after the milk protein meal differed from that of the cod protein meal with a larger AUC calculated up to 240 min. The insulin/C-peptide and the insulin/glucose ratios differed between the meals; the insulin/C-peptide ratio was higher after the milk protein meal compared to the cod, and soy protein meal at 120 min. The insulin/glucose ratio was lower after the cod protein meal compared to the milk, and soy protein meals at 120 min. The results showed that the metabolic responses differed after meals with similar macronutrient composition containing cod-, milk-, or soy protein.     

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

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

Interaction of fat availability and sex on postprandial satiety and cholecystokinin after mixed-food meals

BACKGROUND: Cholecystokinin (CCK) is associated with fat-induced satiety. OBJECTIVE: The primary objective of the present study was to determine, in an acute meal setting, whether the availability of dietary fat for alimentary processing, and hence the stimulation of CCK, affects the postmeal satiety response in men and women. DESIGN: In a within-subjects design, subjects (8 men, 7 women) consumed 1 of 3 isoenergetic mixed-food test meals 1 wk apart in random order. The test meals contained 30% of energy from fat, of which more than two-thirds was derived from whole almonds, almond oil, or a mix of safflower and corn oils. Visual analogue scales were used to assess indexes of satiety at defined time points up to 6 h after meal consumption. Blood was sampled at corresponding time points for measurement of CCK, glucose, insulin, and triacylglycerol. Subsequent food intake was also assessed. RESULTS: All meals suppressed hunger and induced a pattern of satiety that was sex-specific and corresponded with the CCK response. Women had higher plasma CCK concentrations and experienced greater satiety after the almond oil and control meals (fat as oil) than after the whole almond meal (fat in whole food structure). Men showed no differential response among meals for CCK and satiety. Plasma triacylglycerol differed by time among meals but not by sex, and no significant differences in glucose and insulin were found. CONCLUSIONS: The satiety response to dietary fat provided in oil or whole food form is influenced by sex and is dependent on the availability of fat to stimulate CCK release in women but not in men.     

Short-term regulation of food intake in children, young adults and the elderly

OBJECTIVE: The present study investigated the effects of consuming preloads with different macronutrient and energy contents on subsequent intake and subjective feelings of hunger and satiety in children, young adults and the elderly. SUBJECTS: 30 Children (4-6 y), 33 young adults (18-26 y) and 24 elderly (61-86 y). DESIGN: A 'preload test meal' design was applied. Subjects were given four different strawberry yoghurt preloads that varied in energy and macronutrient content, or no yoghurt. Children, young adults and elderly consumed 200, 340 and 300 g of the preload, respectively. One yoghurt was low-fat, low-carbohydrate and low in energy (the control; 0.7 MJ/500 g serving), one yoghurt was high-fat and medium in energy (71% of energy (en%) of fat; 2 MJ/500 g serving), one yoghurt was high-carbohydrate and medium in energy (87 en% of carbohydrate; 2 MJ/500 g serving) and the fourth yoghurt was high-fat and high-carbohydrate and high in energy (42 en% of fat and 53 en% of carbohydrate; 3 MJ/500 g serving). Ninety minutes after preload consumption, subjects had an attractive ad libitum lunch-buffet. Energy intake at lunch and subjective feelings of hunger and satiety were analysed. RESULTS: The ability to compensate at lunch did not differ among the three age groups. Compared to the no-preload condition, all children, young adults and elderly ate significantly less after the high-fat and high-carbohydrate yoghurt. The energy compensation observed in the children ranged between -21% and 34%, in the young adults between 15% and 44% and in the elderly between 17% and 23%. Hunger responses were clearly different between young adults and the elderly. Compared to the no-preload condition, the young adults showed larger differences in their appetite ratings than the elderly, indicating that the elderly were less sensitive to the energy content of the preload than the young adults. CONCLUSION: We conclude that the ability to regulate the food intake within a preload 90 min test meal paradigm did not differ among children, young adults and the elderly. Sponsorship: This study was funded by the European Commission as part of project FAIR-CT95-0574.     

Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum

BACKGROUND: Altering the macronutrient composition of the diet influences hunger and satiety. Studies have compared high- and low-protein diets, but there are few data on carbohydrate content and ketosis on motivation to eat and ad libitum intake. OBJECTIVE: We aimed to compare the hunger, appetite, and weight-loss responses to a high-protein, low-carbohydrate [(LC) ketogenic] and those to a high-protein, medium-carbohydrate [(MC) nonketogenic] diet in obese men feeding ad libitum. DESIGN: Seventeen obese men were studied in a residential trial; food was provided daily. Subjects were offered 2 high-protein (30% of energy) ad libitum diets, each for a 4-wk period-an LC (4% carbohydrate) ketogenic diet and an MC (35% carbohydrate) diet-randomized in a crossover design. Body weight was measured daily, and ketosis was monitored by analysis of plasma and urine samples. Hunger was assessed by using a computerized visual analogue system. RESULTS: Ad libitum energy intakes were lower with the LC diet than with the MC diet [P=0.02; SE of the difference (SED): 0.27] at 7.25 and 7.95 MJ/d, respectively. Over the 4-wk period, hunger was significantly lower (P=0.014; SED: 1.76) and weight loss was significantly greater (P=0.006; SED: 0.62) with the LC diet (6.34 kg) than with the MC diet (4.35 kg). The LC diet induced ketosis with mean 3-hydroxybutyrate concentrations of 1.52 mmol/L in plasma (P=0.036 from baseline; SED: 0.62) and 2.99 mmol/L in urine (P<0.001 from baseline; SED: 0.36). CONCLUSION: In the short term, high-protein, low-carbohydrate ketogenic diets reduce hunger and lower food intake significantly more than do high-protein, medium-carbohydrate nonketogenic diets.     

The degree of fat saturation does not alter glycemic,insulinemic or satiety responses to a starchy staple in healthy men

Inclusion of fat reduces the glycemic response to a carbohydate meal, although the effect of different types of fat on glycemic, insulinemic and satiety responses is unclear. Ten healthy men received 50-g carbohydrate portions of mashed potato with isoenergetic amounts of butter (saturated fatty acid), Sunola oil (monounsaturated fatty acid) or sunflower oil (PUFA) and two 50-g glucose loads on separate days. Capillary blood was collected at regular intervals for 2 h. Satiety ratings were assessed by use of a rating scale. The glycemic index (GI), insulin index (II) and satiety index (SI) scores were calculated. Energy intakes from a meal consumed ad libitum at 2 h and for the remainder of the day were quantified. The GI values ranged from 68 +/- 8 to 74 +/- 10 and the II values ranged from 113 +/- 10 to 122 +/- 17, but there was no effect of fat type. SI scores and subsequent energy intake did not differ among the test meals. Substitution of unsaturated fats for saturated fatty acids had no acute benefits on postprandial glycemia, insulin demand or short-term satiety in young men.     

Plasma cholecystokinin is associated with subjective measures of satiety in women

BACKGROUND: Cholecystokinin is associated with satiety. Fat stimulates cholecystokinin release, and fiber appears to prolong cholecystokinin elevation during the alimentary period. OBJECTIVE: We tested whether adding fiber or fat to a low-fat, low-fiber meal increases cholecystokinin release and enhances subjective measures of satiety and whether the cholecystokinin response correlates with subjective measures of satiety. DESIGN: Three isoenergetic breakfast meals were tested in a randomized crossover design: low fiber, low fat; high fiber, low fat; and low fiber, high fat. Blood samples were drawn from fasted subjects (7 men and 8 women) before and at different time points after test meal consumption for 6 h. Plasma was analyzed for cholecystokinin, insulin, glucose, and triacylglycerols. Visual analogue scales were used to assess subjects' hunger, desire to eat, fullness, and prospective consumption. RESULTS: In the women, the meals higher in fiber or in fat resulted in greater feelings of satiety and in significantly higher cholecystokinin responses than did the low-fat, low-fiber meal. In the men, the increase in cholecystokinin concentration did not differ between meals, but the 2 low-fat meals elicited a greater feeling of satiety than did the high-fat meal. The insulin response was significantly higher for the low-fiber, low-fat meal than for the other 2 meals, and the triacylglycerol response was greatest for the high-fat, low-fiber meal. CONCLUSION: In women, the feeling of satiety caused by cholecystokinin release is enhanced by increasing either the fiber or fat content of a low-fat, low-fiber meal.     

A comparison of effects of fish and beef protein on satiety in normal weight men

BACKGROUND: Previous studies have indicated that fish protein may have a greater effect on satiety compared to other protein sources of animal origin.OBJECTIVE: To compare the effects of fish protein and beef protein meals on hunger and satiety. DESIGN: Twenty-three normal non-smoking, healthy males aged 20-32 years, body mass index 22.5+/-1.8 (s.d.) kg/m(2) participated in a study, with within-subjects design and 1 week between test days. In the morning of the test days, subjects received a standardized breakfast. Four hours after breakfast, subjects were served an iso-energetic protein-rich (40 energy % protein) lunch meal, consisting of either a fish protein dish or a beef protein dish. Four hours after the start of the lunch meals, an ad libitum standardized evening meal was served and the intake of food was measured. Appetite was rated by visual analogue scales (VAS) immediately before and after the meals, as well as every hour between the meals. After the evening meal until bedtime, subjects were asked to record in detail foods and drinks consumed. RESULTS: The repeated VAS-ratings of hunger, satiety and prospective consumption were modelled in a random effects model, taking pre-lunch VAS-ratings into account. After the fish meal, the point estimates were lower for hunger (-2+/-4.8), higher for satiety (8.7+/-6.0) and lower for prospective consumption (-4.9+/-4.7), but they did not reach statistical significance (P satiety=0.88; P hunger=0.15; P prospective=0.30). However, the energy intake at the evening meal displayed significant differences with subjects eating less after the fish protein lunch (2765 vs 3080 KJ, P<0.01) without feeling less satiated. No later energy compensation after the evening meal was found on the test day. CONCLUSION: Although no significant differences in VAS-ratings of satiety or hunger were detected, subjects displayed an 11% reduction in energy intake at the subsequent evening meal.     

Energy,protein, calcium,vitamin D and fibre intakes from meals in residential care establishments in Australia

Residents from high level (nursing homes) and low-level care facilities (hostel) being served the three common diet texture modifications (full diet, soft-minced diet and pureed diet) were assessed. Individual plate waste was estimated at three meals on one day. Fifty-six males and 156 females, mean age 82.9+/-9.5 (SD) years, of which 139 lived in nursing homes (NH) and 76 in hostels (H) were included. Mean total energy served from meals was 5.3 MJ/day, 5.1 to 5.6 MJ/day, 95% confidence intervals (CI), in NH which was less than in H, 5.9 MJ/day (CI 5.6 to 6.2 MJ/day) (P=0.007). Protein and calcium intakes were lower in NH, 44.5g (CI 41.5 to 47.5g), 359.0mg (CI 333.2 to 384.8mg), versus 50.5g (CI 46.6 to 54.3g), 480.5mg (CI 444.3 to 516.7mg) in H (P=0.017, P<0.001 respectively). There was no difference in nutrient/energy ratios, except for protein/energy, which was higher in NH 11.7 (CI 11.3 to 12.2) than in H 9.8 (CI 9.4 to 10.3) (P<0.001). Ability to self-feed had no significant effect on nutrient intakes in NH. The self fed group (N=63) had the following nutrient intakes: energy 4.0 MJ (CI 3.6 to 4.3 MJ), protein 44.6g (CI 40.3 to 48.9g), calcium 356.9mg (CI 316.3 to 397.4mg), fibre 14.9g (CI 13.2 to 16.5g). The assisted group (N=64) had the following nutrient intakes: energy 3.9MJ (CI 3.6 to 4.2MJ), protein 46.0g (CI 40.7 to 49.6), calcium 361.9mg (CI 327.8 to 396.1mg), fibre 14.9g (CI 13.2 to 16.1g). Of NH classified as eating impaired, 36% received no assistance with feeding and had lower intakes of protein 37.8g (CI 33.0 to 42.1g) compared to those receiving some assistance 46.1g (CI 41.3 to 50.9g) (P=0.026). Reduced energy intake accounted for the differences in nutrient intakes between nursing homes and hostels, except for protein. Strategies to effectively monitor nutrient intakes and to identify those with eating impairment are required in order to ensure adequate nutrition of residents in nursing homes and hostels.     

Food intake, hunger, and satiety after preloads in women with eating disorders.

Food intake, food selection, macronutrient intake, sensory-specific satiety, and ratings of hunger and satiety were measured after high- and low-energy salad preloads (2414 kJ, or 172 kJ) or no preload to determine whether patients with eating disorders compensate appropriately for different energy intakes. Subjects were female patients with a DSM-III-R diagnosis of anorexia nervosa with bulimic features or bulimia nervosa, or non patient, normal-weight, nondieters (n = 9/group). At a self-selected lunch 30 min after the preloads, all of the groups reduced intake after the high-energy preload, with the bulimics showing the best compensation. The anorexics chose low-energy foods and in some conditions ate a smaller proportion of fat than did the other groups. The bulimics ate more high-energy foods than did the anorexics. The anorexics demonstrated sensory-specific satiety only after the high-energy salad and the bulimics only after the low-energy salad. Overall, these data suggest that while many of their responses to food are abnormal, patients with eating disorders have some capacity to respond to physiological hunger and satiety cues.     

High protein high fibre snack bars reduce food intake and improve short term glucose and insulin profiles compared with high fat snack bars

The replacement in the diet of refined carbohydrate and fat with fibre and protein has been shown to promote satiety and improve glucose and insulin profiles. It is less clear whether the macronutrient composition of individual foods such as snacks have any meaningful impact on metabolic parameters and satiety. We examined if the consumption of higher protein higher fibre snack bars would result in reducing outcome measures such as food intake and glucose and insulin patterns compared to a conventional isocaloric high fat high refined carbohydrate snack bar. Twenty three women were randomized in a single blind cross over study with 2 interventions, a high fat high sugar snack bar and a comparatively higher protein, higher fibre snack bar intervention. Snack bars were eaten at mid morning and mid afternoon, and a standard breakfast and ad libitum buffet lunch. The glucose and insulin responses over 9 hours were significantly lower (P = 0.014 and P = 0.012 respectively) during the high protein snack bar intervention. Peak glucose levels were also 16% lower after the morning HP bar (P <0.001). The morning high protein bar reduced the energy intake at the buffet lunch meal by 5% (4657 +/- 1025KJ vs 4901 +/- 1186KJ, P < 0.05). Altering the macronutrient composition of a snack bar can assist in reducing the energy intake at a subsequent meal and improve short term glucose and insulin profiles.     

Appetite dysfunction in obese males: evidence for role of hyperinsulinaemia in passive overconsumption with a high fat diet

OBJECTIVE: To test the hypothesis that caloric and fat intake in a pre-load meal have no subsequent effects upon blood glucose and insulin concentrations, perceived hunger, subsequent food intake and appetite control in lean and obese men. DESIGN: Lean and obese men reported to the laboratory in the morning in a fasted state where they were subject to an eating test based on the pre-load-test meal paradigm, using a double-blind protocol. The breakfast pre-load was either a reduced caloric low-fat (LF) meal or an overfeeding high-fat (HF) meal. LF was 20% of each individual's average daily energy requirement (ADER) and comprised 60% carbohydrate, 27% protein, and 13% fat, whilst HF was adjusted to yield 55% of the ADER, and comprised 45% carbohydrate, 22% protein and 43% fat. The pre-loads on both trials were administered as one single mean, and were given in a random order. After 5(1/2) h, an ad libitum test-lunch was given to determine how much energy was consumed. Between the two meals, blood samples were collected and subjective hunger ratings were assessed hourly. These variables were measured at 30-min intervals for 75 min after the ad libitum meal. STUDY PARTICIPANTS: Twelve healthy men, six of whom were lean (BMI 22. 50+/-1.08 kg.m2) and six of whom were obese (BMI 39.05+/-11.63 kg. m2) were recruited. RESULTS: When given 55% of their ADER in a HF pre-load meal, the obese group consumed more energy (5426+/-1126 kJ; F1,20=11.45, P<0.01), than the lean group did (3473+/-1114 kJ), accounting for 45% of the ADER in that meal setting. However, no differences between lean and obese intake were noted at the test meal following a LF pre-load. The lean group exhibited a significant inverse correlation (r=0.628, P<0.05) between serum insulin concentration before eating the test meal and the amount of energy consumed at the test meal, while such a relationship was absent in the obese group. CONCLUSION: The obese males were unable to compensate for the caloric overloading when fed a HF (55% ADER) pre-load at a subsequent test meal, whereas a calorically reduced pre-load (20% ADER) produced similar intakes to the lean control group. The inverse relationship noted in the lean group between insulin levels before the test meal and the energy intake at that test meal suggests that insulin may play a role in the regulation of appetite - satiety mechanism in lean males. The absence of such a relationship in the obese may suggest the site for possible appetite dysfunction contributing to obesity. These results further suggest that when obese individuals consume a high-fat meal they are prone to passive overconsumption, whereas lean study participants appear to be more resistant to such a phenomenon.     

Effect of liquid dietary supplements on energy intake in the elderly

BACKGROUND: Undernutrition is a risk factor for increased mortality in older adults. Therapeutic intervention includes the administration of liquid dietary supplements. OBJECTIVE: We investigated the effect of liquid dietary supplements on satiation, satiety, and energy intake in older adults. DESIGN: This study had 2 phases in a within-subject, repeated-measures design. The energy intake of 15 elderly (aged >70 y) and 15 younger (aged 20-40 y) healthy subjects was measured after 4 liquid preloads: water, high fat, high carbohydrate, and high protein. The preloads were administered within 5 min of a test meal in phase 1 and >or=60 min before the test meal in phase 2. Palatability, fullness, and hunger were assessed by using visual analogue scales. RESULTS: Mean energy consumption of the test meals was significantly lower in the older than in the younger subjects (P = 0.001), as was mean macronutrient consumption of fat and carbohydrate (P = 0.002 and 0.001, respectively). Mean energy intake and macronutrient consumption were higher in phase 2 than in phase 1 in both older and younger subjects (P < 0.05). Satiety lasted longer in older than in younger subjects after the high-protein and high-fat preloads (P = 0.001). CONCLUSION: In the elderly, administration of dietary supplements between meals instead of with meals may be more effective in increasing energy consumption.     

Effects of red pepper on appetite and energy intake

Two studies were conducted to investigate the effects of red pepper (capsaicin) on feeding behaviour and energy intake. In the first study, the effects of dietary red pepper added to high-fat (HF) and high-carbohydrate (HC) meals on subsequent energy and macronutrient intakes were examined in thirteen Japanese female subjects. After the ingestion of a standardized dinner on the previous evening, the subjects ate an experimental breakfast (1883 kJ) of one of the following four types: (1) HF; (2) HF and red pepper (10 g); (3) HC; (4) HC and red pepper. Ad libitum energy and macronutrient intakes were measured at lunch-time. The HC breakfast significantly reduced the desire to eat and hunger after breakfast. The addition of red pepper to the HC breakfast also significantly decreased the desire to eat and hunger before lunch. Differences in diet composition at breakfast time did not affect energy and macronutrient intakes at lunch-time. However, the addition of red pepper to the breakfast significantly decreased protein and fat intakes at lunch-time. In Study 2, the effects of a red-pepper appetizer on subsequent energy and macronutrient intakes were examined in ten Caucasian male subjects. After ingesting a standardized breakfast, the subjects took an experimental appetizer (644 kJ) at lunch-time of one of the following two types: (1) mixed diet and appetizer; (2) mixed diet and red-pepper (6 g) appetizer. The addition of red pepper to the appetizer significantly reduced the cumulative ad libitum energy and carbohydrate intakes during the rest of the lunch and in the snack served several hours later. Moreover, the power spectral analysis of heart rate revealed that this effect of red pepper was associated with an increase in the ratio sympathetic: parasympathetic nervous system activity. These results indicate that the ingestion of red pepper decreases appetite and subsequent protein and fat intakes in Japanese females and energy intake in Caucasian males. Moreover, this effect might be related to an increase in sympathetic nervous system activity in Caucasian males.     

High-calorie fibre-rich breakfast: its effect on satiety

This study was designed to test whether a substantial fibre-rich breakfast could influence satiety sensations and daily energy. In non-consecutive weeks 24 volunteers were given two high-fibre cereals (Kellogg's ‘Bran Flakes’ and Kellogg's ‘All Bran’) in a breakfast meal that accounted for about 20% of the total daily energy intake. During the trial a questionnaire for hunger and satiety sensations was filled out just before, immediately after and 1, 2, 3 and 4 h after breakfast. The more reliable questions in evaluating sensations correlated to hunger and satiety were: ‘How satiated do you feel?’ and ‘How full do you feel?’. Significant differences in the satiety sensations were found for the experimental breakfasts compared to the usual one. There was no statistical differences between the two cereal breakfast meals, however, the highest scores of fullness and satiety always corresponded to the highest fibre content. Furthermore, after the two experimental breakfasts the calorie intake at lunch was lower than after the habitual one. Regression analysis showed a positive linear correlation between the scores corresponding to satiety sensations and the fibre and energy intakes. The findings indicate that a substantial breakfast rich in fibre has a positive impact on subsequent food intake and the sensations associated with satiety.     

Effect of dairy calcium or supplementary calcium intake on postprandial fat metabolism, appetite, and subsequent energy intake

BACKGROUND: High calcium intake has been shown to increase fecal fat excretion. OBJECTIVE: Our aim was to examine whether a high calcium intake from dairy products or from supplements affects postprandial fat metabolism and appetite through fat malabsorption. DESIGN: Four different isocaloric meals were tested in 18 subjects according to a randomized crossover design. The test meals contained high (HC meal: 172 mg/MJ), medium (MC meal: 84 mg/MJ), or low (LC meal: 15 mg/MJ) amounts of calcium from dairy products or a high amount of calcium given as a calcium carbonate supplement (Suppl meal: 183 mg/MJ). Concentrations of plasma total triacylglycerol, chylomicron triacylglycerol, serum total cholesterol, HDL cholesterol, cholecystokinin, glucagon-like peptide 1, ghrelin, peptide YY, glucose, and insulin and appetite sensation were measured before and at regular intervals until 420 min postprandially. RESULTS: Dairy calcium significantly diminished the postprandial lipid response. The baseline adjusted area under the curve for chylomicron triacylglycerol was approximately 17% lower after the MC meal (P = 0.02) and approximately 19% lower after the HC meal (P = 0.007) than after the LC meal and approximately 15% lower after the MC meal (P = 0.0495) and approximately 17% lower after the HC meal (P = 0.02) than after the Suppl meal. No consistent effects of calcium on appetite sensation, or on energy intake at the subsequent meal, or on the postprandial responses of cholecystokinin, glucagon-like peptide 1, ghrelin, peptide YY, insulin, or glucose were observed. CONCLUSIONS: Increased calcium intakes from dairy products attenuate postprandial lipidemia, most probably because of reduced fat absorption, whereas supplementary calcium carbonate does not exert such an effect. This may be due to differences in the chemical form of calcium or to cofactors in dairy products. Calcium did not affect appetite sensation, glucose metabolism, or gut hormone secretion.     

不同米饭对餐后血糖和饱腹感反应的影响

目的研究不同米饭样品的餐后血糖及饱腹感反应。方法 10名空腹健康志愿者食用含碳水化合物50 g的不同米饭样品:籼米饭(IR),黑籼米饭(BI),籼糯米饭(WL)和冷籼糯米饭(RW)。测餐后120 min血糖水平和血浆中胰岛素水平,同时记录180 min内的饱腹感及第二餐摄入的能量,计算血糖生成指数(GI)与胰岛素生成指数(II),以及在餐后1 h,2 h和3 h时各样品的饱腹感指数(SI)。结果无论WL还是RW食用后的GI均高于IR和BI。BI的II和SI最高。第二餐能量摄入最低。II分别与GI和SI具有一定的相关性,而GI和SI之间的相关性不大。结论籼糯米饭经过冷藏以后并不能降低血糖反应,两者均不适合糖尿病人作为主食BI适合需要控制体重和控制血糖者食用。结果提示,相比于GI,II与SI之间的联系可能更密切。