Caloric, but not macronutrient, compensation by humans for required-eating occasions with meals and snack varying in fat and carbohydrate.

Six subjects participated in a residential study assessing the effects of covert macronutrient and energy manipulations during three required-eating occasions (breakfast, lunch, and afternoon snack) on total macronutrient and energy intakes. Overall, energy content of the occasions varied between approximately 3000 and approximately 7000 kJ (approximately 700 and approximately 1700 kcal) with the majority of the differential derived from either fat or carbohydrate (CHO). Each condition (high, medium, and low fat; high, medium, and low CHO; and no required eating) was examined for 2 d. Subjects compensated for the energy content of the required occasions such that only under the low-CHO condition (11,297 +/- 3314 kJ) was total daily energy intake lower than that observed in the absence of required occasions (13,297 +/- 1356 kJ). Only total energy intake under the high-fat condition (12,326 +/- 2548 kJ) was significantly different from its matched CHO condition (high-CHO condition: 14,665 +/- 2686 kJ). In contrast to the clear evidence for caloric compensation, there were no differential effects of condition on macronutrient intake, ie, there was no macronutrient compensation.     

Comparison of high-fat and high-carbohydrate foods in a meal or snack on short-term fat and energy intakes in obese women

The present study aimed to compare the action of high-fat and high-carbohydrate (CHO) foods on meal size (satiation) and post-meal satiety in obese women. A within-subjects design was used; each participant received all four nutritional challenges. Fifteen healthy obese women (age 21-56 years, BMI 35-48 kg/m2) participated; thirteen completed all four test days. On two test days, participants were exposed to a nutritional challenge comprising an ad libitum high-fat or high-CHO lunch. On the other two test days they were exposed to a challenge comprising an ad libitum sweet high-fat or high-CHO mid-afternoon snack. Energy and macronutrient intakes were measured at each eating episode. Visual analogue rating scales were completed periodically to record subjective feelings of appetite. When offered a high-CHO selection of foods at lunch and mid-afternoon participants consumed less energy than when offered a high-fat selection. However, post-meal satiety was similar. Total test-day energy intake was significantly higher when high-fat foods were consumed at lunch, but not as a snack. Consumption of high-fat foods at a lunch and snack increased the amount of fat consumed over the whole test day. In conclusion, energy intake of an eating episode was influenced by nutrient composition in this group of obese women. Consumption of high-fat foods at lunch or as a snack led to overconsumption relative to high-CHO foods. However, high-fat foods at meals may have greater potential to influence daily intake than at snacks, probably because meals are larger eating episodes and therefore give greater opportunity to overconsume.     

Short-term effect of a protein load on appetite and food intake in diseased mildly undernourished elderly people

BACKGROUND & AIMS: Malnutrition is a risk factor for mortality and various morbidities in the elderly. A low-energy intake often prevails and therapeutic interventions include the administration of dietary supplements, sometimes rich in proteins. We have tested the hypothesis that a protein-rich supplement inhibits appetite and decreases voluntary food intake. METHODS: Twelve mildly undernourished (BMI 21.3 +/- 2.4 kg/m2) elderly (84 +/- 7.8 yr) diseased persons were each studied under 3 conditions, in which they were given in random order at breakfast, and on consecutive days: either no supplement, a 250 kcal, 20 g protein supplement or a 250 kcal, 3.5 g protein supplement. Hunger, fullness, and desire to eat sensations were monitored half-hourly from before breakfast until lunch, and hourly from lunch until dinner. Food intake was assessed by weighing food before and after meals. Total energy and macronutrient intakes were calculated over 24 h. RESULTS: Both supplements increased energy intake (+185 kcal protein supplement, +176 kcal). Protein supplementation induced a net 17 g increase in protein intake (P < or = 0.0003). Neither supplement affected spontaneous food intake at lunch, dinner, or over the 24 h. Protein supplementation significantly depressed appetite in the breakfast to lunch period. CONCLUSION: A 250 kcal, 20 g protein supplement depresses hunger without affecting food intake in elderly diseased mildly undernourished persons.     

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.     

Sensory-specific satiety in obese and normal-weight women

BACKGROUND: Sensory-specific satiety has been found to play an important role in food choice and meal termination, and it might be a factor contributing to obesity. OBJECTIVE: We hypothesized that obese and normal-weight people have different sensitivities to sensory-specific satiety for high-fat foods. DESIGN: Sensory-specific satiety was measured in 21 obese [x body mass index (BMI; in kg/m(2)): 33.1] and 23 normal-weight (BMI: 22.8) women who were matched for restrained eating behavior, physical activity, age, and smoking behavior. Food intake, appetite ratings, and liking scores before and after an ad libitum lunch were measured. Products differed in fat content and taste (ie, low-fat sweet, low-fat savory, high-fat sweet, and high-fat savory), and the subjects tested all 4 products. In the first study, sandwiches were tested; in the second study, snacks were tested. RESULTS: Sensory-specific satiety for all products was observed in both subject groups. No significant differences were observed between the obese and normal-weight subjects in either sensory-specific satiety or food intake for any of the products or product categories tested. Taste (sweet or savory) had a significantly (P < 0.05) stronger effect on sensory-specific satiety than did fat content. Appetite ratings strongly decreased after lunch, and appetite for a meal or snack after lunch was significantly higher in obese than in normal-weight subjects, whereas scores before lunch did not differ significantly. CONCLUSIONS: Obese and normal-weight people do not differ in their sensitivity to sensory-specific satiety, and factors other than fat content have the greatest effect on sensory-specific satiety.     

Decreased caloric intake in normal-weight patients with bulimia: comparison with female volunteers

Patients with bulimia (binge-purge syndrome) frequently complain that they consume a very restrictive diet to avoid gaining weight. To investigate this claim, 23 hospitalized bulimic patients were assessed daily for body weight, caloric intake, macronutrient diet content, activity measures, and body composition estimates during weight-stable periods. Bulimic patients ate fewer kilocalories per kilogram body weight (22.1 +/- 4.6 kcal/kg) than did age-matched normal women (29.7 +/- 6.5 kcal/kg) but had similar activity levels and body composition. Clinical variables, such as history of laxative abuse, anorexia, or obesity, and physiological characteristics, such as body weight, activity level, or dietary content, could not account for this difference in caloric consumption. Bulimic patients tended to eat a diet lower in fat and higher in protein than did control subjects. These results agree with observations of increased efficiency of caloric utilization in obese patients and support patient complaints of a tendency to gain weight easily.     

Short-term effects of different amounts of protein, fats, and carbohydrates on satiety.

This study investigated the satiating efficiencies of proteins, fats, and carbohydrates (CHOs). Twenty-nine female, normal-weight subjects each received 10 liquid breakfasts, which varied in energy and macronutrient contents. Besides a zero condition [0.3 MJ (8 kcal)], there were three energy levels [0.42, 1.05, and 1.67 MJ (100, 250, and 400 kcal)] combined with three dominant sources of macronutrients (99% of energy from CHO, 92% of energy from fat, and 77% of energy from protein). After breakfast the subjects were not allowed to eat or drink (except water) for 3.5 h. They then recorded their voluntary food intake for the remainder of the day. Subjects also rated their subjective feelings concerning food intake on five different types of appetite. The results showed that neither energy content nor macronutrient composition of the liquid breakfasts had any effect on energy and macronutrient intake during lunch and the remainder of the day. Ratings of different types of appetite showed an increasing satiating effect with increasing energy content of the breakfasts. Proteins, fats, and CHOs had similar effects on appetite.     

The effects of phenylpropanolamine on Zucker rats selected for fat food preference

Treatments of human and rodent obesity frequently involve administration of amphetamine derivatives, much like phenylpropanolamine, which suppress food intake. The Zucker rat is a commonly employed model of youth-onset obesity in which the homozygous genotype manifests hyperphagia as well as other characteristics that parallel human obesity. Using a macronutrient selection procedure, we examined phenylpropanolamine's differential actions in controlling dietary intake, spontaneous open-field activity, and regional hypothalamic neurotransmitter levels in obese female Zucker rats of varying fat food preference. We hypothesized that phenylpropanolamine would alter hypothalamic monoamine levels differently in low-fat preferring and high-fat preferring Zucker rats, and hence affect feeding behavior and activity differently in these two groups. It was found that in high-fat preferring animals, phenylpropanolamine significantly decreased spontaneous open-field activity, decreased only carbohydrate caloric intake, and increased serotonin and 5-HIAA levels in the paraventricular nucleus (PVN). In low-fat preferring animals, phenylpropanolamine decreased carbohydrate, protein, and total caloric intake, had no significant effect of spontaneous activity, and increased serotonin and 5-hydroxyindole acetic acid levels in the PVN. Inherent and induced physiological differences of low-fat and high-fat preferring animals are discussed as well as phenylpropanolamine's potential in combination drug therapy for the treatment of human hyperphagic obesity.     

Evening ready-to-eat cereal consumption contributes to weight management

OBJECTIVES: Post dinner snacking may constitute a significant proportion of total daily energy intake and contribute to overweight and obesity in some individuals (night snackers). This study tested the hypothesis that providing a structured snack in the form of a "ready-to-eat" breakfast cereal would help regulate excess energy intake and contribute to weight loss in night snackers. METHODS: Adults (18 to 65 years of age, BMI kg/m2 > or = 25), with self-reported night snacking behaviors, were randomized into a cereal group (CR) and a no-cereal group (NC). During a period of 4 weeks, the cereal group was instructed to consume a serving of ready-to-eat cereal with low-fat milk 90 minutes after their evening meal. Concurrently, the non-cereal group continued their regular diet ad libitum. RESULTS: At baseline, there were no significant differences between groups for age, body weight, body mass index, daily caloric intake, or evening caloric intake. There was a correlation between number of days of compliance with post-dinner cereal consumption and weight loss (r = -0.36, p = 0.057). After 4 weeks, the compliant subjects (cereal intake > or = 20 d) lost -1.85 +/- 3.56 lbs vs. -0.39 +/- 3.1 lb for the NC group (p = 0.06). Compared to baseline, the compliant CR group reduced their total daily caloric intake by -396.50 +/- 641.6 kcal (p < 0.02), whereas, the NC group experienced a reduction of -23.22 +/- 889.60 kcal/day during the same period (p = ns). Reduction in post-dinner calorie intake for the compliant CR group was significantly greater compared to the NC group (-141.74 +/- 385.58 kcal vs. 85.82 +/- 374.70 kcal; p = 0.042). CONCLUSION: Eating ready-to-eat cereal after the evening meal may attenuate caloric intake in night snackers and promote weight loss in compliant individuals.     

Effects of long-term intervention with low- and high-glycaemic-index breakfasts on food intake in children aged 8-11 years

The aim of the present study was to investigate the effects of long-term intervention of low-glycaemic-index (GI) v. high-GI breakfasts on energy and macronutrient intakes in children aged 8-11 years. Preadolescent children were assigned to one of two groups in a random cross-over design. Each group was given low-GI and high-GI breakfasts on two non-consecutive days per week for 10 weeks per breakfast type. Each breakfast provided approximately 1273 kJ (300 kcal) and was closely matched for macronutrient and dietary fibre content. Subsequent food intake at an ad libitum buffet lunch was recorded and daily energy and macronutrient intakes were measured by 24 h recall and 3 d food diaries. There was a tendency towards a reduced energy intake at lunch following the low-GI breakfast compared with the high-GI breakfast, although the mean difference of 75 kJ (18 kcal) was not significant (P = 0.406). In particular, there was a trend towards a reduced energy intake in the low-GI arm compared with the high-GI arm among boys. In addition, data from the 3 d food diaries showed that there was a tendency towards a reduced energy intake during the low-GI compared with the high-GI study period. In conclusion, although the difference in energy intake following the low-GI and high-GI breakfasts was not statistically significant, the reduced energy intake following the low-GI breakfast is encouraging. Both dietary fibre and carbohydrate type may affect GI, thus their potential and relative modulating effect on appetite requires further investigation.     

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.     

Sources of variance in milk and caloric intakes in breast-fed infants: implications for lactation study design and interpretation

Between-individual variation (BIV) and day-to-day variation (DDV) of total caloric and human milk intakes were examined in 17 infants. Nine were studied at months 5 and 6; 8 at months 6 and 7. All 17 were exclusively breast-fed for 5 full mo after which solid foods were added to the diet. Each infant was studied for five consecutive 24-h periods during which serial measurements were made of milk intake (test weighing) and solid food intake (pre- and postfeeding jar weighing). Total daily caloric intakes (kcal/day) were (mean +/- SD) 492 +/- 57, 547 +/- 70, and 567 +/- 98 at months 5, 6, and 7, respectively. Estimates of caloric intakes (kcal/kg/day) adjusted for body weight were 65.9 +/- 6.7, 72.6 +/- 11.2, and 70.9 +/- 13.0 at months 5, 6, and 7, respectively. Milk intakes (g/day) were 735 +/- 85, 640 +/- 106, and 562 +/- 214 at months 5, 6, and 7, respectively. BIV of milk intake increased after the introduction of solid foods. DDV (expressed as coefficient of variation) of caloric intake was nearly constant at each monthly observation and BIV increased from 8.8 at month 5 to 14.6 at month 7. The numbers of 24-h periods and subjects required for estimates of known precision of caloric and milk intakes of older breast-fed infants can be determined from these estimates of variance.     

The effect of increased beverage portion size on energy intake at a meal

OBJECTIVE: This study examined the impact of increasing beverage portion size on beverage and food intake. SUBJECTS: Thirty-three subjects, 18 women and 15 men, were included. INTERVENTION: In a crossover design, subjects consumed lunch in the laboratory once a week for 6 weeks. At each test lunch, the same foods were served, but the beverage served was varied in type (cola, diet cola, or water) and portion size (360 g/12 fl oz or 540 g/18 fl oz). MAIN OUTCOME MEASURES: Beverage intake (g); energy intake from foods and beverages (kcal); and ratings of hunger, satiety, and characteristics of the foods and beverages served. RESULTS: Increasing beverage portion size significantly increased the weight of beverage consumed, regardless of the type of beverage served (P < 0.05). As a consequence, for the caloric beverage, energy intake from the beverage increased by 10% for women and 26% for men when there was a 50% increase in the portion served (P < 0.01). Food intake did not differ between conditions, so when the energy from the caloric beverage was added to the energy from food, total energy intake at lunch was increased significantly (P < 0.001) compared with noncaloric beverages. CONCLUSIONS: Serving a larger portion of beverage resulted in increased beverage consumption, and increased energy intake from the beverage when a caloric beverage was served. Serving a caloric beverage resulted in an overall increase in total energy consumed at lunch. Therefore, replacing caloric beverages with low-calorie or noncaloric beverages can be an effective strategy for decreasing energy intake.     

Compensation for caloric dilution in humans given unrestricted access to food in a residential laboratory

Six adult male research volunteers, in two groups of three subjects each, lived continuously in a residential laboratory for 14 days. All contact with the experimenters was through a networked computer system and subjects' behaviors, including food intake, were continuously recorded. During the first part of the day, subjects remained in their private rooms doing work activities. During the remainder of the day, they had the option to socialize with each other. A wide variety of food items were continuously available. Subjects were in complete control of their pattern of food intake and could consume any item, or number of items, at any time during the day. On days 6 through 11, reduced calorie versions of approximately one third of the food items were covertly substituted for the regular caloric content items. This manipulation decreased intake from the reduced-calorie group of foods by 500 kcal. The subjects immediately and completely compensated for the loss of calories by increasing the number of non-calorie-manipulated food items consumed. When regular calorie foods were again available during the last 3 days of the experiment, subjects failed to compensate for this increase in caloric intake. Thus, under conditions of unlimited access to food, human volunteers completely compensated for caloric dilution, but were less accurate in responding to increases in caloric intake.     

Effects of macronutrient content and energy density of snacks consumed in a satiety state on the onset of the next meal

We examined the effects of nutrient composition of a 1 MJ afternoon snack, consumed in a satiety state, on the spontaneous onset of the next meal in 11 young male subjects deprived of any temporal cues. All subjects attended four experimental sessions scheduled 2 weeks apart. The first, baseline, session served to establish: (1) the subjects' ad libitum lunch intake, (2) the latency of the spontaneous request for dinner following lunch, (3) ad libitum food intake at dinner. Lunches provided during the next three sessions were based on baseline lunch intakes. During the following three sessions, conducted in counterbalanced order, subjects were given a high-fat (58% of energy from fat), a high-protein (77%) or a high-carbohydrate (84%) snack to be consumed 240 min after the beginning of lunch. Latency to dinner and the amount of energy consumed at dinner were two dependent variables. Consumption of a high-protein snack delayed the request for dinner by 60 min. In contrast, high-fat snack delayed dinner request by 25 min, whereas high-carbohydrate snack delayed dinner request by 34 min. Snack composition had no impact on energy or macronutrient intakes during dinner.     

Diet intervention methods to reduce fat intake: nutrient and food group composition of self-selected low-fat diets

A multicentered pilot study was conducted to test an intervention protocol designed to reduce fat intake to 15% of energy intake. Eligible subjects were postmenopausal women with stage II breast cancer whose baseline fat intake was more than 30% of energy intake. The low-fat diet intervention protocol consisted of bi-weekly individual counseling sessions with emphasis on substitution of lower-fat foods for high-fat foods and maintenance of nutritional adequacy. Nutrient intakes were calculated from 4-day food records collected at baseline and after 3 months of diet intervention. Mean daily fat intake for the 17 patients on the low-fat diet dropped significantly from 38.4 +/- 4.3% of energy intake at baseline to 22.8 +/- 7.8% at 3 months (p less than .001). A 25% reduction in mean energy intake, from 1,840 +/- 419 kcal at baseline to 1,365 +/- 291 kcal at 3 months, was accompanied by significant increases in protein and carbohydrate as percent of energy intake. A mean weight loss of 2.8 kg and a 7.7% reduction in serum cholesterol were observed; both changes were significant at the p less than .01 level. Absolute intakes of zinc and magnesium were significantly reduced. However, mean intake on the low-fat diet for 14 vitamins and minerals, including zinc and magnesium, exceeded two-thirds of the 1989 Recommended Dietary Allowances (RDAs). When expressed as nutrient density (i.e., amount of nutrient per 1,000 kcal), increases were observed for all micronutrients. These results support the hypothesis that a nutritionally adequate low-fat diet can be successfully implemented in a highly motivated, free-living population.     

The relationship between daytime and nighttime food intake in an obese night-eater

Some obese individuals consume food during awakenings from nighttime sleep. Three studies were conducted on a 28-year-old morbidly obese male with chronic sleeping complaints and insignificant weight loss, despite self-reported daily caloric restriction: I. For 3 mo, the subject recorded food intake for 24-h periods. Mean daytime intake was 1286 kcal +/- 386 (SD), and mean nighttime intake was 1036 kcal +/- 487 (SD). Caloric values of daytime and nighttime intake were negatively correlated, r = -0.22, df= 82, p < .05. II. Seven consecutive 24-h food intake recordings were obtained with an automated formula dispenser when the subject was an inpatient on a metabolic ward and received ad libitum formula as his sole food source. Mean daytime intake was 1245 +/- 662 (SD), and mean nighttime intake was 231 +/- 236 (SD). There was a non-significant negative correlation between daytime and nighttime intake, r = -0.32, df = 5, NS. III. The subject underwent polysomnographic studies on 2 non-consecutive nights, following the administration of either a low (600 kcal) or high (1800 kcal) daytime caloric condition. The subject, upon awakening from nighttime sleep, could eat from a platter of sandwich quarters placed at his bedside. The addition of 1200 kcal to daytime intake decreased nighttime intake by 654 kcal, or by 55% of the additional calories delivered during the day. The three studies (I, II, and III) show that daytime food intake can be negatively correlated with nighttime intake, and that daytime intake can influence nighttime intake in a documented obese night-eater.     

Exercise increases the proportion of fat utilization during short-term consumption of a high-fat diet

BACKGROUND: Increases in energy substrate oxidation occur at different rates after an increase in either fat or carbohydrate intake. Adaptations to increased fat intake are relatively slow and are influenced by activity level. OBJECTIVE: We tested the hypothesis that increased levels of daily activity, as influenced by added exercise, would have a graded effect on the rate of compensatory adjustment to a short-term high-fat diet. DESIGN: Daily total energy expenditure and macronutrient oxidation were measured at 3 physical activity levels (PALs) by using a whole-room indirect calorimeter in 10 adult women as they transitioned from a 1-d low-fat (30% of energy) control diet to a 4-d high-fat (50% of energy) diet. The 3 PALs (1.4, 1.6, and 1.8) were provided daily by increases in bicycle ergometer exercise time. RESULTS: An increase in physical activity led to a greater increase in the nonprotein respiratory exchange ratio (-0.047 +/- 0.02, -0.064 +/- 0.02, and -0.071 +/- 0.02; P < 0.0001) and 24-h fat oxidation (113 +/- 24, 125 +/- 19, and 147 +/- 20 g/d; P < 0.0001) for PALs of 1.4, 1.6, and 1.8, respectively, after the transition from the low-fat control diet to the high-fat diet. Random-effects analysis found a significant (P = 0.003) relation between PAL and the compensatory fat oxidation response to a high-fat diet. CONCLUSIONS: Amounts of exercise consistent with the Institute of Medicine's recommendations reduce the time required to match fat oxidation to a change in the percentage of fat in the diet. Because short-term consumption of high-fat diets is thought to contribute to excess fat accumulation, regular exercise should be protective and should help maintain a healthy body composition.     

The effect of exercise on food intake in men and women

To study the effect of acute exercise on caloric intake in normal-weight young people, food intake was monitored in 10 men and 10 women during consecutive 5-d periods, one with and one without exercise. Food intake during the exercise period was compared with that during the control period. Caloric intake during the control period was 2467 +/- 165 kcal/d (means +/- SEM) for men and 1831 +/- 103 kcal/d for women. During the exercise period the men increased their caloric intake to 2658 +/- 188 kcal/d and the women's caloric intake remained unchanged, 1830 +/- 91 kcal/d. Caloric intake was not affected by sequence of treatment or duration of protocol. Men responded to 5 d of acute exercise with increased caloric intake (208 +/- 64 kcal/d), which was insufficient to compensate for the caloric cost of exercise (596 kcal/d above resting metabolic rate). Women did not change their caloric intake despite expending 382 kcals/d during exercise. Consequently, both normal-weight men and women were in negative caloric balance during the exercise period.     

Influence of dietary carbohydrates and glycaemic response on subjective appetite and food intake in healthy elderly persons

Increased satiety and decreased food intake are reported following the consumption of low glycaemic index (GI) foods, which gradually increase blood glucose. This observation, however, is not uniformly supported and few studies have examined the impact of different GI foods on satiety and intake in the elderly. After an overnight fast, 10 men and 10 women (aged 60-82 years) consumed similar amounts of available carbohydrate as high (glucose drink or potatoes) or low (barley) GI foods or a non-energy placebo drink on four mornings. Blood glucose and subjective appetite were measured throughout a 120 min post-ingestion period, followed by consumption of an ad libitum lunch. Differences in plasma glucose after test food ingestion (glucose > potatoes > barley > placebo; P < 0.03) did not predict subjective appetite or lunch intake. Potatoes increased subjective satiety the most, followed by barley, then glucose, which trended towards greater satiety than placebo. Potatoes led to less hunger than placebo (P = 0.0023) and less prospective consumption than the other three foods (P < 0.0083), and potatoes and barley led to greater fullness than glucose and placebo (P < 0.0001). Lunch intake was decreased, compared with placebo (502 +/- 47 kcal, P < 0.031), by potatoes (405 +/- 40 kcal) and barley (441 +/- 41 kcal); however, only potatoes (41.9 +/- 12.3%) led to greater compensation at lunch for test food ingestion compared with glucose (11.9 +/- 9.5%, P = 0.016). These results suggest that elderly subjects are sensitive to the effects of different foods on subjective appetite and food intake, and that the GI of the foods tested did not predict their effects on satiety and food intake.