Behavioral components of high-fat diet hyperphagia: meal size and postprandial satiety

Previously, rats fed a high-fat liquid diet (HF) ad libitum consumed more kilocalories and had greater weight gain than rats fed a liquid high-carbohydrate diet (HC) of equivalent energy density (Warwick, Z. S., and H. P. Weingarten. Am. J. Physiol. Regulatory Integrative Comp. Physiol. 269: R30-R37, 1995). The present series of experiments sought to clarify the behavioral expression of HF hyperphagia by comparing HF and HC with regard to meal size and magnitude of postingestive satiety effect. Meal size of HF was greater than HC at 2.3 kcal/ml and also when diets were formulated at 1.15 kcal/ml. In a preload-test meal paradigm, an orally consumed HF preload was less satiating than a calorically equivalent HC preload across a range of preload volumes and intermeal intervals. Sensory-specific satiety was ruled out as an explanation of the relatively greater intake of test meal after an HF preload meal; an intragastrically delivered HF preload was less satiating than intragastric HC. Furthermore, a fat (corn oil emulsion) preload was less satiating than a carbohydrate (sucrose) preload when an evaporated milk test meal was used. These findings indicate that hyperphagia on an HF diet is expressed in increased meal size and decreased intermeal interval.     

Pre-meal water consumption reduces meal energy intake in older but not younger subjects

Objective: To determine whether the consumption of water 30 minutes before an ad libitum meal reduces meal energy intake in young and older adults. Research Methods and Procedures: Healthy, non‐obese young (n = 29; age, 21 to 35 years) and older (n = 21; age, 60 to 80 years) individuals were provided with an ad libitum lunch meal on two occasions. Thirty minutes before the lunch meals, subjects were given either a water preload (WP: 375 mL, women; 500 mL, men) or no preload (NP). Energy intake at the two lunch meals was measured. Visual analog scales were used to assess changes in hunger, fullness, and thirst during the meal studies. Results: There was no significant difference in meal energy intake between conditions in the young subjects (892 + 51 vs. 913 ± 54 kcal for NP and WP, respectively; p = 0.65). However, meal energy intake after the WP was significantly reduced relative to the NP condition in the older subjects (682 + 53 vs. 624 ± 56 kcal for NP and WP, respectively; p = 0.02). This effect was caused primarily by the reduction in meal energy intake after water consumption in older men. Hunger ratings were lower and fullness ratings were higher in older compared with younger adults (p < 0.01). Fullness ratings were higher in the WP condition compared with the NP condition for all subjects (p = 0.01). No age differences in thirst were detected during the test meals. Discussion: Under acute test meal conditions, pre‐meal water consumption reduces meal energy intake in older but not younger adults. Because older adults are at increased risk for overweight and obesity, intervention studies are needed to determine whether pre‐meal water consumption is an effective long‐term weight management strategy for the aging population.     

Effect of Chronic Caloric Restriction on the Synchronization of Various Physiological Measures in Old Female Fischer 344 Rats

-A variety of physiological and behavioral parameters which relate to metabolism were continuously monitored in 18 month old female Fischer 344 rats which were maintained on either ad libitum or reduced calorie diets. Caloric restriction (CR) stimulated average motor activity per day, the duration of each feeding episode, food consumed per episode, and water consumed per gram lean body mass (LBM). However, CR limited total food consumption, feeding time, number of feeding episodes per day, total eating and drinking time, and the daily ratio of food consumed to water consumed, CR also decreased average body temperature per day, O₂ consumption, CO₂, production, and respiratory quotient. A variety of parameters concerning water consumption were not affected. CR rats ate their food immediately when food was presented during the light span, while ad libitum fed animals ate numerous small meals throughout the entire dark span. An anticipatory response to restricted feeding was also noted. Total motor activity, metabolism, and body temperature increased just prior to scheduled feeding and reached maximum values shortly after feeding, suggesting that these parameters were highly synchronized to feeding. Females and males were found to respond to caloric restriction in a similar fashion. Dramatic changes in respiratory quotient and body temperature suggest rapid shifts between metabolic pathways (glycolysis to giuconeogenesis) to obtain optimal efficiency. Lower body temperature and metabolism may provide protection against DNA damage, thereby increasing the survival potential of restricted rats. These responses may provide insight into the mechanisms by which caloric restriction acts to extend life span.     

IMPACT OF DIFFERENCES IN TASTE TEST RATINGS ON THE CONSUMPTION OF MILK IN BOTH A LABORATORY AND A FOODSERVICE SETTING1

The objective of this study was to observe the impact of a perceptible difference in the liking of milk on consumption of the milk in both laboratory and cafeteria settings. We produced milk with no flavor defects and milk with a light oxidized flavor. The defect-free milk scored about 1 point higher than the off-flavored milk on a 9-point hedonic scale. We placed the same two milk products in the milk dispenser in a dormitory cafeteria for a total of 32 dinner meals and measured the amount of milk consumed. A subset of subjects from the cafeteria population also consumed the milks in a laboratory consumption test. In a second laboratory consumption test a different group of subjects consumed the two milks. The liking difference had no impact on consumption in the dormitory food service setting and either no impact or a small impact on consumption in a laboratory setting.     

Cholecystokinin and satiety

Fourteen normal volunteers were given intravenous or subcutaneous injections of the synthetic C-terminal octapeptide of cholecystokinin (SQ-19, 844) 10 or 20 minutes prior to the ad libitum consumption of a liquid noontime meal. The drug was given in doses of 20 ng/kg, 40 ng/kg, or 80 ng/kg versus equal volumes of a normal saline control in a random double blind fashion. There was no significant difference between the volumes of lunch consumed after injecting SQ-19, 844 and saline control except one patient who consumed less (p<.05) after 20 ng/kg SQ-19, 844 intravenously. This is interpreted as a random event since higher doses of SQ-19, 844 did not give similar results. It is concluded that cholecystokinin does not reduce food intake and doubt is raised regarding its role as an endogenous satiety signal in man.     

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/m²) 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 (β = ?0.87, P < 0.001) showed a 44% greater decline in weight over the 12 weeks than the nonwater group (β = ?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.     

Acute effect of alginate-based preload on satiety feelings, energy intake, and gastric emptying rate in healthy subjects

Viscous dietary fibers such as sodium alginate extracted from brown seaweed have received much attention lately for their potential role in energy regulation through the inhibition of energy intake and increase of satiety feelings. The aim of our study was to investigate the effect on postprandial satiety feelings, energy intake, and gastric emptying rate (GER), by the paracetamol method, of two different volumes of an alginate-based preload in normal-weight subjects. In a four-way placebo-controlled, double-blind, crossover trial, 20 subjects (age: 25.9 ± 3.4 years; BMI: 23.5 ± 1.7 kg/m(2)) were randomly assigned to receive a 3% preload concentration of either low volume (LV; 9.9 g alginate in 330 ml) or high volume (HV; 15.0 g alginate in 500 ml) alginate-based beverage, or an iso-volume placebo beverage. The preloads were ingested 30 min before a fixed breakfast and again before an ad libitum lunch. Consumption of LV-alginate preload induced a significantly lower (8.0%) energy intake than the placebo beverage (P = 0.040) at the following lunch meal, without differences in satiety feelings or paracetamol concentrations. The HV alginate significantly increased satiety feelings (P = 0.038), reduced hunger (P = 0.042) and the feeling of prospective food consumption (P = 0.027), and reduced area under the curve (iAUC) paracetamol concentrations compared to the placebo (P = 0.05). However, only a 5.5% reduction in energy intake was observed for HV alginate (P = 0.20). Although they are somewhat contradictory, our results suggest that alginate consumption does affect satiety feelings and energy intake. However, further investigation on the volume of alginate administered is needed before inferring that this fiber has a possible role in short-term energy regulation.     

微波—吸附法提取朱砂玉兰鲜花香气成分

朱砂玉兰(Magnolia soulangeana)鲜花经微波处理,用XAD-4吸附提取头香物质。该方法不仅可以较快速地得到挥发性成分,而且提取的精油能保持原鲜花的香气香味。本文还讨论了用微波处理与不处理朱砂玉兰鲜花样品以及用水蒸汽蒸馏3种方法得到的精油在收率及化学成分上的差异及变化。     

Influence of eating modalities on water intake in dog (author's transl)]

Food and water intake of a dog which had free access to water were studied in three experimental circumstances: 1) Food given ad libitum. 2) Food given at fixed hours. 3) Food deprivation for four days followed by resumption of food intake. A) The results indicate the water intake follows a pattern, the profile, range and duration of which can be modified within 24 hrs. In spite of modifications related to food intake, a typical profile remains which suggests that water is taken according to a program which is at least partly indepdent of food intake. B) Under experimental condition 1, food and water intake were weakly related, probably revealing an acquired relationship between the meal weight and the water intake which immediately precedes and follows food intake. The correlation was strengthened when the dog was forced to eat only once a day (observation 2). On the contrary, after a period of starvation (observation 3) the previous relationship between meal weight and water intake lessens and others appear which suggest the action of direct mechanisms of shortage compensation as far as water and food are concerned.     

IMPROVED PERFORMANCE OF THE AROMASCAN A32S ELECTRONIC NOSE AND ITS POTENTIAL FOR DETECTING AROMA DIFFERENCES IN DAIRY PRODUCTS

The Aromascan A32S, an "electronic nose", was evaluated for its performance under conditions of total humidity control. Initially, it was shown that the very high concentration of water vapor in the headspace above a variety of food products used for this study, in comparison with the concentration of their aroma compounds, completely determined the response of the instrument's sensors. Differentiation between the food aromas was impossible. Only when the concentration of a nonaqueous analyte was increased to approximately the water vapor concentration was perfect distinction achieved between air samples with and without analyte. It was obvious that the instrument in its original form would not be capable of distinguishing subtle aroma differences as are encountered within one type of product in quality assurance, storage trials, taint studies etc. However, significant modification of the original version of the instrument and of the sample presentation procedure improved its performance. Now it was possible to distinguish in certain cases, not only between water vapor and food aromas, but also between different samples of the same types of dairy products. These tests were complemented by sensory evaluation by untrained panels. In this form, the Aromascan A32S offers a new vista for successful and reliable application in the food area.     

Self-selected fluid volume and flavor strength does not alter fluid intake,body mass loss,or physiological strain during moderate-intensity exercise in the heat

IntroductionThe purpose of this study was to determine the effects of ad libitum flavor and fluid intake on changes in body mass (BM) and physiological strain during moderate intensity exercise in the heat.MethodsTen subjects (24±3yrs, 7M/3F) performed 60 min of treadmill walking at 1.3 m/s and 7% grade in an environmental chamber set to 33 °C and 10% relative humidity while carrying a 22.7 kg pack on two different occasions. Subjects consumed either plain water or water plus flavor (Infuze), ad libitum, at each visit. Pre and post exercise, fluid consumption (change in fluid reservoir weight) and BM (nude) were measured. During exercise, heart rate (HR), systolic blood pressure (SBP), rate of perceived exertion (RPE), oxygen consumption (VO₂), respiratory exchange ratio (RER), core temperature (T_C), and physiological strain index (PSI) were recorded every 15 min during exercise.ResultsNo significant differences were observed for fluid consumption between fluid conditions (512 ± 97.2 mL water vs. 414.3 ± 62.5 mL Infuze). Despite a significant decrease from baseline, there were no significant differences in overall change of BM (Δ −1.18 vs. −0.64 Kg) or percent body weight loss for water and Infuze conditions, respectively (1.58 ± 0.6 and 0.79 ± 0.2%). Furthermore, there were no significant differences in HR (144 ± 6 vs. 143 ± 8 bpm), SBP (157 ± 5 vs. 155 ± 5 mmHg), RPE, VO₂ (27.4 ± 0.9 vs. 28.1 ± 1.2 ml/Kg/min), RER, T_C (38.1 ± 0.1 vs. 37.0 ± 0.1 °C), and peak PSI (5.4 ± 0.4 vs. 5.7 ± 0.8) between conditions.ConclusionsOffering individuals the choice to actively manipulate flavor strength did not significantly influence ad libitum fluid consumption, fluid loss, or physiological strain during 60 min of moderate intensity exercise in the heat.     

EFFECT OF QUANTITY CONSUMED ON MEASURES OF LIKING FOR SALT CONCENTRATIONS IN SOUP

Two studies are reported on the effect ofingestion on the relative-to-ideal ratings of salt in soup. In the first study there was a reduction in the measure of ideal concentration from pre- to post-ingestion, with subjects consuming the soups ad libitum. However, a measure of ideal concentration derived from several small samples presented in each session agreed well with the final post-ingestion ideal. A measure of most preferred concentration of salt based on total soup consumption was unrelated to the other measures. In the second experiment, the post-ingestion decrease in most preferred salt concentration was replicated when subjects consumed a fixed quantity of soup. The post-ingestion ideal was similar to that derived from rating either several small samples in one session or one single small sample per session.     

Isolating neural correlates of the pacemaker for food anticipation

Mice fed a single daily meal at intervals within the circadian range exhibit food anticipatory activity. Previous investigations strongly suggest that this behaviour is regulated by a circadian pacemaker entrained to the timing of fasting/refeeding. The neural correlate(s) of this pacemaker, the food entrainable oscillator (FEO), whether found in a neural network or a single locus, remain unknown. This study used a canonical property of circadian pacemakers, the ability to continue oscillating after removal of the entraining stimulus, to isolate activation within the neural correlates of food entrainable oscillator from all other mechanisms driving food anticipatory activity. It was hypothesized that continued anticipatory activation of central nuclei, after restricted feeding and a return to ad libitum feeding, would elucidate a neural representation of the signaling circuits responsible for the timekeeping component of the food entrainable oscillator. Animals were entrained to a temporally constrained meal then placed back on ad libitum feeding for several days until food anticipatory activity was abolished. Activation of nuclei throughout the brain was quantified using stereological analysis of c-FOS expressing cells and compared against both ad libitum fed and food entrained controls. Several hypothalamic and brainstem nuclei remained activated at the previous time of food anticipation, implicating them in the timekeeping mechanism necessary to track previous meal presentation. This study also provides a proof of concept for an experimental paradigm useful to further investigate the anatomical and molecular substrates of the FEO.     

PLEASANTNESS OF COOKIES, JUICE AND THEIR COMBINATIONS RATED IN BRIEF TASTE TESTS AND FOLLOWING AD LIBITUM CONSUMPTION

Four combinations of cookie and juice were presented to 42 subjects for ratings of pleasantness of the items and their combinations (Experiment 1). Pleasantness of juice contributed to the pleasantness of a combination more than that of cookie (multiple regression analysis). In Experiment 2, subjects (N=41) rated each combination after ad libitum consumption in four separate sessions. Pleasantness of a cookie contributed more to the pleasantness of a combination than that of juice, and the average R² obtained in multiple regression analysis was higher than in Experiment 1, suggesting that ratings after ad libitum consumption are more reliable. Pleasantness ratings explained ad libitum consumption of an item up to 23%, but perceived hunger and thirst, and consumption of the other item were at least equally good predictors. It is concluded that the pleasantness is only one among the multiple factors affecting amounts consumed in laboratory conditions.     

Photoperiod influences the critical caloric intake necessary to maintain reproduction among male deer mice (Peromyscus maniculatus).

The concept of critical day length is well established among rodents; reproductive function is maintained when day lengths are greater than some specific threshold. In addition to day length cues, seasonal breeding in deer mice can also be regulated by food availability. The caloric threshold necessary to support reproduction remains unspecified for seasonally breeding rodents. The present study examined the interaction between photoperiod and food availability on reproductive function in adult male deer mice (Peromyscus maniculatus). A critical caloric intake profile was constructed in long (16L:8D) and short (8L:16D) photoperiods; groups of deer mice in both photoperiods either received food ad libitum or 90, 80, or 70% of their individual ad libitum food intake for 10 wk. At autopsy, paired testes, epididymides, and seminal vesicles were removed and weighed. Body mass, total body fat, and total body water contents were also obtained. Short, as compared to long, day lengths inhibited the reproductive systems of male deer mice. However, food consumption interacted with photoperiod to affect reproductive function. Significant reductions in reproductive organ size as well as spermatogenic activity were observed among short-day mice after a 10% reduction in ad libitum food intake. Long-day animals required a 20% reduction in caloric intake to depress reproductive function. Body mass and total body water content were generally unaffected by either photoperiod or food consumption. Total body fat content was reduced in short- as compared to long-day mice. Individual reproductive responsiveness to short days increased as food availability decreased.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of rest and exercise at a simulated altitude of 4,000 m on appetite, energy intake, and plasma concentrations of acylated ghrelin and peptide YY

The reason for high altitude anorexia is unclear but could involve alterations in the appetite hormones ghrelin and peptide YY (PYY). This study examined the effect of resting and exercising in hypoxia (12.7% O(2); ～4,000 m) on appetite, energy intake, and plasma concentrations of acylated ghrelin and PYY. Ten healthy males completed four, 7-h trials in an environmental chamber in a random order. The four trials were control-normoxia, control-hypoxia, exercise-normoxia, and exercise-hypoxia. During exercise trials, participants ran for 60 min at 70% of altitude-specific maximal oxygen consumption (Vo(2max)) and then rested. Participants rested throughout control trials. A standardized meal was consumed at 2 h and an ad libitum buffet meal at 5.5 h. Area under the curve values for hunger (assessed using visual analog scales) tended to be lower during hypoxic trials than normoxic trials (repeated-measures ANOVA, P = 0.07). Ad libitum energy intake was lower (P = 0.001) in hypoxia (5,291 ± 2,189 kJ) than normoxia (7,718 ± 2,356 kJ; means ± SD). Mean plasma acylated ghrelin concentrations were lower in hypoxia than normoxia (82 ± 66 vs. 100 ± 69 pg/ml; P = 0.005) while PYY concentrations tended to be higher in normoxia (32 ± 4 vs. 30 ± 3 pmol/l; P = 0.059). Exercise suppressed hunger and acylated ghrelin and increased PYY but did not influence ad libitum energy intake. These findings confirm that hypoxia suppresses hunger and food intake. Further research is required to determine if decreased concentrations of acylated ghrelin orchestrate this suppression.     

A COMPARISON OF TASTE TEST RATINGS,REPEATED CONSUMPTION,AND POSTCONSUMPTION RATINGS OF DIFFERENT STRENGTHS OF ICED TEA1

One objective of this study was to compare taste test ratings with amounts consumed and postconsumption ratings made as iced teas of different strengths were repeatedly consumed. The second objective was to determine whether sensory specific satiety could be used as a rapid indicator of long term acceptability of the teas. Subjects first rated their liking of and the flavor intensity of several samples of lemon flavored iced tea. Two tea concentrations were selected from this test to represent distinctly different flavor intensities. Taste test liking ratings of the strong concentration were higher than those of the weak concentration. Subjects consumed either the strong or the weak iced tea ad lib on 20 different afternoons over a 2-month period and rated their liking of the tea after each session. We measured the amount of tea consumed each time. On repeated consumption the subjects liked the weaker tea better than the stronger tea. Subjects consumed about the same amount of each tea. A different group of 15 subjects participated in a sensory specific satiety study of the same two teas. Those subjects drank more of the weak tea than the strong tea.     

Reductions in entrée energy density increase children's vegetable intake and reduce energy intake

The energy density (ED; kcal/g) of an entrée influences children's energy intake (EI), but the effect of simultaneously changing both ED and portion size of an entrée on preschool children's EI is unknown. In this within-subject crossover study, 3- to 5-year-old children (30 boys, 31 girls) in a daycare facility were served a test lunch once/week for 4 weeks. The amount and type of vegetables and cheeses incorporated into the sauce of a pasta entrée were manipulated to create two versions that varied in ED by 25% (1.6 or 1.2 kcal/g). Across the weeks, each version of the entrée was served to the children in each of two portion sizes (400 or 300 g). Lunch, consumed ad libitum, also included carrots, applesauce, and milk. Decreasing ED of the entrée by 25% significantly (P<0.0001) reduced children's EI of the entrée by 25% (63.1+/-8.3 kcal) and EI at lunch by 17% (60.7+/-8.9 kcal). Increasing the proportion of vegetables in the pasta entrée increased children's vegetable intake at lunch by half of a serving of vegetables (P<0.01). Decreasing portion size of the entrée by 25% did not significantly affect children's total food intake or EI at lunch. Therefore, reducing the ED of a lunch entrée resulted in a reduction in children's EI from the entrée and from the meal in both portion size conditions. Decreasing ED by incorporating more vegetables into recipes is an effective way of reducing children's EI while increasing their vegetable intake.