Water incorporated into a food but not served with a food decreases energy intake in lean women.

BACKGROUND: Previous research showed that decreasing the energy density (kJ/g) of foods by adding water to them can lead to reductions in energy intake. Few studies have examined how water consumed as a beverage affects food intake. OBJECTIVE: This study examined the effects of water, both served with a food and incorporated into a food, on satiety. DESIGN: In a within-subjects design, 24 lean women consumed breakfast, lunch, and dinner in our laboratory 1 d/wk for 4 wk. Subjects received 1 of 3 isoenergetic (1128 kJ) preloads 17 min before lunch on 3 d and no preload on 1 d. The preloads consisted of 1) chicken rice casserole, 2) chicken rice casserole served with a glass of water (356 g), and 3) chicken rice soup. The soup contained the same ingredients (type and amount) as the casserole that was served with water. RESULTS: Decreasing the energy density of and increasing the volume of the preload by adding water to it significantly increased fullness and reduced hunger and subsequent energy intake at lunch. The equivalent amount of water served as a beverage with a food did not affect satiety. Energy intake at lunch was 1209 +/- 125 kJ after the soup compared with 1657 +/- 148 and 1639 +/- 148 kJ after the casserole with and without water, respectively. Subjects did not compensate at dinner for this reduction in lunch intake. CONCLUSION: Consuming foods with a high water content more effectively reduced subsequent energy intake than did drinking water with food.     

Increasing preload volume with water reduces rated appetite but not food intake in healthy men even with minimum delay between preload and test meal

The role of gastric volume in the short-term control of eating in humans remains unclear, with some studies reporting that food volume alone can reduce appetite but others finding no such effect. A recent study in our laboratory, found effects of preload volume on subjective appetite (hunger, fullness) but not intake, and found effects of preload energy on intake but not appetite. That study used an interval of 30 min between serving preloads and the test meal, and the present study attempted to maximise the effects of the volume manipulation by removing the delay between the preload and test meal. We administered four soup-based preloads varying in volume (150 and 450 ml) using water, and energy density (1.4 and 4.2 kJ/ml) using maltodextrin, producing three energy levels (209, 629, 629 and 1886 kJ; repeated measures). These were followed immediately by an unlimited hot pasta lunch, during which food weight was monitored continuously by computer. Increasing soup volume at constant energy (629 kJ) reduced appetite ratings, but not intake. In contrast, increasing soup energy at constant volume (450 ml) reduced intake, without affecting appetite. The discrepancies between our results and other reported studies suggest that volume is more influential when intakes are large, or that there may be a threshold concentration for nutrients in the GI tract before volume alone is tangibly expressed in subsequent eating.     

Lupin-enriched bread increases satiety and reduces energy intake acutely

BACKGROUND: Protein and fiber may be important determinants of satiety. Lupin kernel flour is a novel food ingredient that is rich in protein and fiber. OBJECTIVE: The objective was to investigate the effects of lupin kernel flour-enriched bread (LB) on satiety and energy intake in humans. DESIGN: Two randomized controlled crossover trials were performed to compare the acute effects of LB with those of white bread (WB). In study 1, the subjects (n = 16) completed 4 treatments 1 wk apart: WB breakfast (as toast) and WB lunch (as sandwiches), WB breakfast and LB lunch, LB breakfast and WB lunch, and LB breakfast and LB lunch. Energy intake at all breakfast meals was matched (1655 kJ), and ad libitum energy intake at lunch, 3 h after breakfast, was measured. In study 2, the subjects (n = 17) completed 2 treatments 1 wk apart: WB breakfast and LB breakfast (each 1655 kJ). Blood samples were taken at baseline and at regular intervals for 3 h after breakfast. RESULTS: In study 1, the LB breakfast resulted in significantly higher self-reported satiety (P < 0.001) and lower energy intake (kJ) at lunch (-488; 95% CI: -798, -178) than did the WB breakfast. The LB lunch resulted in a significantly lower within-meal energy intake (kJ) at lunch (-1028; 95% CI: -1338, -727) than did the WB lunch. In study 2, compared with the WB breakfast, the LB breakfast significantly altered the 3-h postmeal plasma ghrelin response (P = 0.04) and resulted in significantly lower mean 3-h plasma ghrelin concentrations (P = 0.009). CONCLUSION: A novel food enriched in protein and fiber derived from lupin kernel flour significantly influences energy intake acutely.     

Increasing Preload Volume with Water Reduces Rated Appetite But Not Food Intake in Healthy Men Even with Minimum Delay Between Preload and Test Meal

Abstract

The role of gastric volume in the short-term control of eating in humans remains unclear, with some studies reporting that food volume alone can reduce appetite but others finding no such effect. A recent study in our laboratory, found effects of preload volume on subjective appetite (hunger, fullness) but not intake, and found effects of preload energy on intake but not appetite. That study used an interval of 30 min between serving preloads and the test meal, and the present study attempted to maximise the effects of the volume manipulation by removing the delay between the preload and test meal. We administered four soup-based preloads varying in volume (150 and 450 ml) using water, and energy density (1.4 and 4.2 kJ/ml) using maltodextrin, producing three energy levels (209, 629, 629 and 1886 kJ; repeated measures). These were followed immediately by an unlimited hot pasta lunch, during which food weight was monitored continuously by computer. Increasing soup volume at constant energy (629 kJ) reduced appetite ratings, but not intake. In contrast, increasing soup energy at constant volume (450 ml) reduced intake, without affecting appetite. The discrepancies between our results and other reported studies suggest that volume is more influential when intakes are large, or that there may be a threshold concentration for nutrients in the GI tract before volume alone is tangibly expressed in subsequent eating.     

The level of carbonation of a sugar-sweetened beverage preload affects satiety and short-term energy and food intakes

The consumption of sugar-sweetened beverages is associated with increased incidence of overweight and obesity, and a factor underlying this putative link could be the relatively low levels of satiety that may be induced by these beverages. Although many sugar-sweetened beverages are carbonated, little attention has been given to the potential effects of level of carbonation on satiety and subsequent intakes. We hypothesized that increasing the level of carbonation in a sugar-sweetened beverage would increase satiety and decrease intakes in the short term. Using a randomized, within-subject cross-over design, thirty non-obese subjects (fifteen women, fifteen men) participated on three occasions, 1 week apart. Following a standard breakfast, subjects consumed a beverage preload 10 min before consuming a lunch ad libitum. Preloads were the same sugar-sweetened beverage (400 ml, 639 kJ) with three levels of carbonation, which were low (1.7 volumes), medium (2.5 volumes) and high (3.7 volumes). Satiety was assessed using visual analogue scales and intakes were measured at the lunch and for the rest of the day. Compared with the beverage with low carbonation, consumption of the beverages with medium and high carbonation led to significantly (P < 0.05) higher satiety until lunch, when intakes of food and energy were significantly (P < 0.05) lower. There were no significant effects on satiety following lunch or on intakes for the rest of the day. This short-term study suggests that the level of carbonation may need to be taken into account when assessing potential effects of beverages on satiety and intake.     

Soup preloads in a variety of forms reduce meal energy intake

Consuming soup can enhance satiety and reduce energy intake. Little is known about the influence on energy intake and satiety of varying the form of soup by altering the blending of ingredients. We tested the effects on meal intake of consuming different forms of soup as a preload: broth and vegetables served separately, chunky vegetable soup, chunky-pureed vegetable soup, or pureed vegetable soup. Normal-weight men and women (n = 60) came to the laboratory for lunch once a week for 5 weeks. Each week, one of four compulsory preloads, or no preload, was consumed prior to lunch. A test meal was consumed ad libitum 15 min after the soup was served. Results showed that consuming soup significantly reduced test meal intake and total meal energy intake (preload + test meal) compared to having no soup. When soup was consumed, subjects reduced meal energy intake by 20% (134+/-25 kcal; 561+/-105 kJ). The type of soup had no significant effect on test meal intake or total meal energy intake. Consuming a preload of low-energy-dense soup, in a variety of forms, is one strategy for moderating energy intake in adults.     

Increased satiety after intake of a chocolate milk drink compared with a carbonated beverage, but no difference in subsequent ad libitum lunch intake

The rising rate of obesity has been blamed on increased consumption of sugar-sweetened soft drinks, such as carbonated sodas, which fail to satisfy hunger. The objective of the present study was to compare the effect on appetite and energy intake of a sugar-sweetened beverage (cola) and a chocolate milk drink, matched for energy content and volume. It was hypothesised that chocolate milk may be more satiating because of its protein content. Twenty-two healthy young men (age 23 (SD 1 x 8) years) of normal weight (BMI 22 x 2 (SD 1 x 5) kg/m2) were recruited to the randomised cross-over study. Visual analogue scales were used to record subjective appetite ratings every 30 min on each of two test days. A drink of 500 ml cola or chocolate milk (900 kJ) was ingested 30 min before an ad libitum lunch. Satiety and fullness were significantly greater (P=0 x 0007, P=0 x 0004, respectively) 30 min after chocolate milk than after cola. Ratings of prospective consumption and hunger were significantly greater after cola than after chocolate milk, both immediately after preload intake (P=0 x 008, P=0 x 01, respectively) and 30 min afterwards (P=0 x 004, P=0 x 01, respectively). There was no significant difference (P=0 x 42) in ad libitum lunch intake after ingestion of chocolate milk (3145 (SD 1268) kJ) compared with cola (3286 (SD 1346) kJ). The results support the hypothesis that sweetened soft drinks are different from milk products in their impact on short-term hunger and satiety, although differences in subjective appetite scores were not translated into differences in energy intake.     

Substrate oxidation and control of food intake in men after a fat-substitute meal compared with meals supplemented with an isoenergetic load of carbohydrate, long-chain triacylglycerols, or medium-chain triacylglycerols.

BACKGROUND: It has been suggested that hunger may be delayed and food intake reduced under metabolic conditions that spare carbohydrate oxidation. OBJECTIVE: Our objective was to examine the role of glucose metabolism in the control of food intake in men by using medium-chain triacylglycerols (MCTs) to spare carbohydrate oxidation. DESIGN: In 10 male volunteers, isolated and deprived of any time cues, we studied the effects of 4 lunches on hunger ratings, the duration of satiety, the amount of food ingested at dinner, energy expenditure, substrate oxidation, and plasma variables until the time of the dinner request. One lunch was a basic 2310-kJ meal containing 40 kJ fat substitute (Sub lunch). The 3 other lunches consisted of the same basic meal supplemented with either 1200 kJ long-chain triacylglycerols (LCT lunch), 1200 kJ MCTs (MCT lunch), or 900 kJ carbohydrate plus 300 kJ LCTs (Cho lunch). RESULTS: Energy expenditure was not significantly different after the different lunches, but carbohydrate oxidation was lower after the MCT and LCT lunches than after the Cho lunch. Fat oxidation was greater after the MCT and LCT lunches. The time of the dinner request was significantly delayed after the Cho lunch. Food intake at dinner was significantly lower after the MCT lunch than after the Sub and Cho lunches, but the dinner meal request was not delayed. CONCLUSION: Carbohydrate may have a greater role in the duration of satiety than does fat, but MCTs may play an active role in other aspects of the control of food intake, especially in satiation at the next meal.     

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.     

Sex and cognitive dietary restraint influence cholecystokinin release and satiety in response to preloads varying in fatty acid composition and content

The aim of the study was to evaluate the effect of preloads differing in fatty acid composition, content, and delivery form on acute behavioral, subjective, and biological outcomes of satiety. Four energy- and volume-matched preloads were tested in normal weight men and women (n = 12 and 13, respectively), using a random, crossover design. Preloads were semisolid shakes differing in fat source [walnut or safflower (SAFF)], delivery [ground walnuts (WNT) or walnut oil (WOL)] or content [39% fat energy (SAFF, WNT, WOL) or 4% low-fat control (LFC)]. Blood was collected and subjective satiety assessed at 0 (fasting), 15, 30, and 45 min after preload consumption. Lunch (test meal) was provided thereafter. Energy intake at lunch was not affected by preload; however, subjects selected more carbohydrate, fiber-rich foods at the test meal lunch after walnut preloads than after LFC or SAFF preloads. Compared with the LFC preload, appetite satisfaction was significantly greater after SAFF and WNT, but not after WOL. Women were hungrier after SAFF than after WOL, whereas men were less hungry after SAFF and LFC than after WOL or WNT. Plasma cholecystokinin (CCK) concentrations reflected preload fat content and availability, particularly among men; CCK was higher after WOL and SAFF preloads than after LFC or WNT preloads. Plasma insulin was higher after LFC and SAFF preloads, corresponding to hunger suppression in men. Dietary restraint was associated with a blunted CCK response to preloads, whereas insulin was not affected by restraint. The results indicate that test meal energy intake after preloads containing approximately 40% walnut or safflower fat or 4% fat did not differ; however, walnut consumption may promote food patterns consistent with consuming diets higher in fiber.     

No differences in satiety or energy intake after high-fructose corn syrup, sucrose, or milk preloads

BACKGROUND: It is unclear whether energy-containing drinks, especially those sweetened with high-fructose corn syrup (HFCS), promote positive energy balance and thereby play a role in the development of obesity. OBJECTIVE: The objective was to examine the satiating effects of HFCS and sucrose in comparison with milk and a diet drink. DESIGN: The effects of four 800-mL drinks [corrected] containing no energy or 1.5 MJ from sucrose, HFCS, or milk on satiety were assessed, first in 15 men and 15 women with a mean (+/-SD) body mass index (BMI; in kg/m(2)) of 22.1 +/- 1.9 according to visual analogue scales (VAS) and blood variables and second in 20 men and 20 women (BMI: 22.4 +/- 2.1) according to ingestion of a standardized ad libitum meal (granola cereal + yogurt, 10.1 kJ/g). RESULTS: Fifty minutes after consumption of the 1.5-MJ preload drinks containing sucrose, HFCS, or milk, 170%-mm VAS changes in satiety were observed. Glucagon-like peptide 1 (GLP-1) (P < 0.001) and ghrelin (P < 0.05) concentrations changed accordingly. Compensatory energy intake did not differ significantly between the 3 preloads and ranged from 30% to 45%. Energy intake compensations were related to satiety (r = 0.35, P < 0.05). No differences were observed between the effects of the sucrose- and HFCS-containing drinks on changes in VAS and on insulin, glucose, GLP-1, and ghrelin concentrations. Changes in appetite VAS ratings were a function of changes in GLP-1, ghrelin, insulin, and glucose concentrations. CONCLUSION: Energy balance consequences of HFCS-sweetened soft drinks are not different from those of other isoenergetic drinks, eg, a sucrose-drink or milk.     

Familial aggregation of energy intake in children

BACKGROUND: Uncompensated overnutrition promotes obesity, but the controls of children's eating behavior are poorly understood. Insights may be achieved by testing whether the eating patterns of children are associated with demographic variables or whether they aggregate among family members. OBJECTIVE: We tested whether children's total energy intake and macronutrient intake and their ability to compensate for earlier energy intake were associated with sociodemographic variables and anthropometric indexes. We also tested whether these behavioral traits aggregate among siblings. DESIGN: Thirty-two sibling pairs aged 3-7 y consumed a multi-item lunch preceded by a low-energy (12.55 kJ) or high-energy (627.60 kJ) preload drink. Mixed-models regression tested the associations between children's energy intake, demographic variables, and anthropometric measures. An intraclass correlation coefficient quantified the family correlation of the measures of children's eating. RESULTS: Children consumed significantly more total energy after consuming the low-energy preload ( +/- SD: 2237.39 +/- 1176.45 kJ) than after consuming the high-energy preload (1601.18 +/- 930.65 kJ). Compensation ability was unrelated to the children's age, sex, or ethnicity. Total energy and macronutrient intake, but not compensation propensity, were associated among siblings. CONCLUSIONS: The familial association of total energy and macronutrient intakes, independent of anthropometric measures, suggests genetic or home environmental influences specific to these behaviors. Short-term energy compensation, although very accurate within this sample, showed no significant familial correlation.     

Sex differences in acute energy intake regulation

The purpose of this investigation was to determine if energy intake compensation is more accurate in males compared to females matched for age, habitual physical activity, cardiorespiratory fitness, and dietary cognitive restraint. Healthy, nonobese young men (n=12) and women (n=12) were provided with an ad libitum lunch meal on two occasions. Thirty minutes prior to the lunch meals, subjects were given either a yogurt preload (YP; 500 mL, 1988 kJ, men; 375 mL, 1507 kJ, women) or no preload (NP). Energy intake at the two lunch meals was measured. Visual analog scales were used to assess changes in hunger and fullness. Blood glucose concentrations were also determined. Energy intake compensation for the YP was significantly more accurate in the male compared to the female subjects (86.2+/-5.0 vs. 73.6+/-4.8% compensation). There were no sex differences in perceptions of hunger and satiety. In the pooled sample, hunger ratings were significantly higher in the NP condition, but there were no significant differences in fullness ratings between test meals. In the YP condition, glycemic response to the preload and the ad libitum meal was significantly higher in males compared to females. These results suggest that under acute test meal conditions, energy intake regulation is more accurate in males. Relative inability to regulate energy intake may predispose females to gain weight over time.     

Caloric compensation and sensory specific satiety: evidence for self regulation of food intake by young children

Twenty-one two and half- to five-year-old children and 26 25- to 35-year-old adults participated in an experiment designed to provide evidence for two behavioral mechanisms involved in self regulation of food intake: caloric compensation and sensory specific satiety. All participants were seen in two lunch sessions that differed in the caloric density of the preload presented. To obtain evidence on sensory specific satiety, preference data were obtained immediately before and after, and 20 min after preload consumption. Subjects then ate an ad libitum lunch and consumption was recorded. Both children's and adults' preferences for the food eaten declined relative to foods not eaten, providing the first evidence of sensory specific satiety in children. The patterns of preference did not differ with the caloric density of the food eaten. Children showed much clearer evidence for caloric compensation than did the adults.     

Oral supplements differing in fat and carbohydrate content: effect on the appetite and food intake of undernourished elderly patients

BACKGROUND & AIMS: Since fat, relative to other macronutrients, has low satiety and high energy density, it may have therapeutic application for supplementing energy intake. This study compared the effect of isoenergetic (1050 kJ) high fat or high carbohydrate oral supplements, given at breakfast, on the short-term appetite and energy intake in undernourished elderly subjects. METHODS: Sixteen hospitalised, undernourished (body mass index: 20 +/- 3 kg/m2), elderly (77 +/- 8 yr) people were randomly allocated to a control or 1 of 2 supplement groups [fat: carbohydrate: protein (% energy) was 70:25:5 or 25:70:5]. In each group, energy intake (24-h food consumption) and appetite (visual analogue scales) were assessed over 3 consecutive days. RESULTS: Mean energy intake significantly (P = 0.0035) increased following supplementation: high fat 6973 kJ/d, high carbohydrate 6906 kJ/d vs. control 6079 kJ/d but mean voluntary 24-h energy intake remained unaffected. Compared to controls, supplemented subjects experienced reduced hunger (P = 0.07) between breakfast and lunch, but showed no difference over the whole day (P = 0.55). CONCLUSIONS: Under these study conditions a 1050 kJ oral supplement, irrespective of macronutrient composition, does not cause voluntary short-term energy intake compensation in undernourished elderly people.     

Does the consumption of caloric and non-caloric beverages with a meal affect energy intake?

Beverages are frequently consumed with meals, but their influence on meal energy intake is not understood. We hypothesized that differences in the energy, nutrient content, and sensory properties of beverages consumed with a meal would affect intake. Forty-four women ate lunch in the laboratory once a week for 6 weeks. Lunch was consumed ad libitum, and was served with one of five beverages that were consumed in full, or no beverage. The beverages were 360 g of water, diet cola, regular cola, orange juice, and 1% milk. Results showed an effect of beverage type on meal intake (p<0.0001). Energy intake did not differ among the non-caloric and no-beverage conditions. Similarly, energy intake from lunch (including beverage) did not differ among the caloric beverage conditions. When a caloric beverage (156 kcal; 653 kJ) was consumed with the meal, energy intake was 104+/-16 kcal (435+/-67 kJ) greater than when a non-caloric beverage or no beverage was consumed. Subjects' ratings of fullness after lunch did not differ among the beverage conditions, but were lower for the no-beverage condition. These results show that when caloric beverages are consumed with a meal they add to energy intake from food, without significantly affecting satiety ratings.     

Combined effects of energy density and portion size on energy intake in women

BACKGROUND: Increases in both the portion size and energy density of food have both been shown to increase energy intake, but the combined effects of such increases have not been investigated. OBJECTIVE: The objective was to determine the combined effects of energy density and portion size on energy intake in women. DESIGN: This study used a within-subjects design. Once a week for 6 wk, 39 women were served breakfast, lunch, and dinner ad libitum. The main entrée at lunch was formulated in 2 versions that varied in energy density (5.23 or 7.32 kJ/g), each of which was served in 3 different portion sizes (500, 700, or 900 g). The 2 versions were matched for macronutrient composition and palatability. Breakfast and dinner were standard meals. RESULTS: Increases in portion size and energy density led to independent and additive increases in energy intake (P <0.0001). Subjects consumed 56% more energy (925 kJ) when served the largest portion of the higher energy-dense entrée than when served the smallest portion of the lower energy-dense entrée. Subjects did not compensate for the additional intake by eating less at the subsequent meal. Despite substantial differences in energy intake, no systematic differences in ratings of hunger and fullness across conditions were observed. CONCLUSIONS: The energy density and the portion size of a food act independently to affect energy intake. The findings indicate that large portions of foods with a high energy density may facilitate the overconsumption of energy.     

Effects of consuming mycoprotein, tofu or chicken upon subsequent eating behaviour, hunger and safety

This study tested if: (1) a preload of mycoprotein and tofu consumed before a lunch meal have a greater effect on satiety when compared to a chicken preload, (2) the mycoprotein and tofu preloads, compared to chicken, are not associated with compensation or eating more food at a subsequent dinner meal. These hypotheses were tested in a controlled laboratory study using universal eating monitors to measure food intake and visual analogue scales to monitor hunger and satiety. Forty-two overweight adult females consumed three meals in the laboratory on 3 test days. At lunch, isocaloric pasta preloads, containing mycoprotein, tofu, or chicken, varied across the days in a balanced order. The findings of the study supported the two hypotheses. Mycoprotein and tofu preloads, in comparison to the chicken preload, were associated with lower food intake shortly after consuming the preload at lunch. Food intake following consumption of mycoprotein and tofu did not differ, and participants did not compensate for lower food intake at lunch by consuming more food at dinner. The findings suggest that mycoprotein and tofu have satiating properties that persist for several hours after a meal. These findings have significant implications for the development of foods that are low in kilojoules, but are also filling.     

Short-term effects of a snack including dried prunes on energy intake and satiety in normal-weight individuals

The purpose of this study was to test the hypothesis that a preload including dried prunes consumed as a snack before a meal, compared to an isoenergetic and equal weighed bread product preload would: (a) have greater short-term effect on satiety measured by subsequent ad libitum meal intake, (b) induce greater satiety as assessed by visual analogue scales (VAS), and (c) reduce appetite for dessert offered shortly after lunch.Forty-five healthy, normal-weight subjects participated in this randomised within-subject crossover study. Statistical analysis of the results showed that when subjects consumed the preload that included dried prunes, also consumed less amount of dessert and had lower total energy intake at meal. Additionally, subjects' feeling of hunger, desire and motivation to eat, as assessed with the use of VAS, were lower at all time points between snack and meal. Since macronutrients content of both preloads were similar, the satiating power of prunes could be due to their relatively high fiber content.Identifying meal patterns and foods that promote satiety without increasing considerably the overall energy intake is very important. The addition of dried prunes to a snack seems to promote satiety besides providing valuable nutrients.     

Energy expenditure, satiety, and plasma ghrelin, glucagon-like peptide 1, and peptide tyrosine-tyrosine concentrations following a single high-protein lunch

High-protein (HP) foods are more satiating and have a higher thermogenic effect than normal protein foods over the short-term as well as the long-term. We hypothesized that acute effects of higher protein intake on satiety may be related to acute metabolic and hormonal responses. The study was a single-blind, randomized, crossover design. Subjects underwent 2 indirect calorimetry tests for measurement of energy expenditure (EE) and substrate oxidation. After a standard subject-specific breakfast, subjects received 1 of 2 randomly assigned treatments: an appropriate protein (AP) lunch (10% energy (E) protein, 60%E carbohydrate, 30%E fat), or a HP lunch (25%E protein, 45%E carbohydrate, 30%E fat). The increase in postlunch EE tended to be greater after the HP lunch (0.85 +/- 0.32 kJ/min) than after the AP lunch (0.73 +/- 0.22 kJ/min) (P = 0.07). The respiratory quotient did not differ between the HP (0.84 +/- 0.04) and the AP (0.86 +/- 0.04) treatments. Satiety visual analogue scales (VAS) scores were significantly higher 30 and 120 min after the HP lunch than after the AP lunch. The area under the curve of the VAS score for satiety was higher after the HP lunch (263 +/- 61 mm/h) than after the AP lunch (AP 236 +/- 76 mm/h) (P < 0.02). Effects of the meals on satiety and diet-induced thermogenesis did not occur simultaneously with changes in plasma ghrelin, glucagon-like peptide 1, and peptide tyrosine-tyrosine concentrations. A single HP lunch, therefore, does not exert its acute effect on satiety through increased concentrations of satiety-related hormones. Other factors, which may explain the HP effect on satiety, may be metabolites or amino acids.