The effect of an incremental increase in exercise on appetite, eating behaviour and energy balance in lean men and women feeding ad libitum

The effects of incremental exercise on appetite, energy intake (EI), expenditure (EE) and balance (EB) in lean men and women were examined. Six men (age 29.7 (SD 5.9) years, weight 75.2 (SD 15.3) kg, height 1.75 (SD 0.11) m) and six women (age 24.7 (SD 5.9) years, weight 66.7 (SD 9.10) kg, height 1.70 (SD 0.09) m) were each studied three times during a 16 d protocol, corresponding to no additional exercise (Nex), moderate-intensity exercise (Mex; 1.5-2.0 MJ/d) and high-intensity exercise (Hex; 3.0-4.0 MJ/d) regimens. Subjects were fed to EB during days 1-2, and during days 3-16 they fed ad libitum from a medium-fat diet of constant composition. Daily EE, assessed using the doubly labelled water method, was 9.2, 11.6 and 13.7 MJ/d (P < 0.001; SED 0.45) for the women and 12.2, 14.0 and 16.7 MJ/d (P = 0.007; SED 1.11) for the men on the Nex, Mex and Hex treatments, respectively. EI was 8.3, 8.6 and 9.9 MJ/d (P = 0.118; SED 0.72) for the women and 10.6, 11.6 and 12.0 MJ/d (P = 0.031; SED 0.47) for the men, respectively. On average, subjects compensated for about 30 % of the exercise-induced energy deficit. However, the degree of compensation varied considerably among individuals. The present study captured the initial compensation in EI for exercise-induced energy deficits. Total compensation would take a matter of weeks.     

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.     

Nutrient balance and energy expenditure during ad libitum feeding of high-fat and high-carbohydrate diets in humans.

To study the influence of diet composition on regulation of body weight, we fed 21 weight-stable subjects (11 lean, 10 obese) high-carbohydrate (HC) and high-fat (HF) diets for 1 wk each. Although diet composition was fixed, total energy intake was unrestricted. Subjects had a higher energy intake on the HF (11,039 +/- 2700 kJ/d) than on the HC (10,672 +/- 2617 kJ/d) diet (P less than 0.05), but energy expenditure was not different between diets. On day 7 of the HC diet, carbohydrate (CHO) oxidation was significantly related to CHO intake with the slope of the regression line 0.99, suggesting that overall CHO balance was near zero. However, the slope of the regression line was greater for obese than for lean subjects. On day 7 of the HF diet, fat oxidation was significantly related to fat intake but the slope of the line was 0.50, suggesting that overall fat balance was positive. However, this relationship was due entirely to lean subjects, with obese subjects showing no relationship between fat intake and oxidation.     

Glycaemic index of meals affects appetite sensation but not energy balance in active males

Background

Foods with low glycaemic index (LGI) are reported to suppress appetite mainly in overweight population but have not been investigated in athletic adults.

Objective

The aim of this study was to compare the short-term effects of LGI and high GI (HGI) meals over a day on subsequent subjective appetite sensation, energy intake, energy expenditure, energy balance and resting metabolic rate in physically active males.

Methods

This cross-sectional randomized crossover study included 14 active males (mean ± SD; age 34.5 ± 8.9 years, body mass index 22.8 ± 2.1 kg m^?2) to consume LGI and HGI meals on two separate days. On each trial day, participants consumed a breakfast in the laboratory and then left with a packed lunch, dinner and snacks. Appetite scores, energy intake and expenditure were assessed.

Results

The area under the curve for appetite scores of the HGI trial was significantly smaller than that of the LGI trial during the laboratory period (p = 0.027) and throughout the day (p = 0.009). No significant differences in energy intake, energy expenditure, energy balance and resting metabolic rate were found between groups, between the trial days and between the corresponding post-trial days.

Conclusions

These results show that frequent ingestion of the HGI meals, contrary to the previous reports, suppresses appetite more than that of LGI meals, but did not affect energy balance in physically active normal-weight males.     

Induced changes in the consumption of coffee alter ad libitum dietary intake and physical activity level

Dietary trials with subjects on a freely selected diet may be affected by unwanted behavioural changes. Few studies, if any, have examined changes in coffee consumption and possible concomitant changes in diet and health-related habits. The aim of the present study was to examine whether induced changes in coffee consumption lead to changes in food habits and leisure-time physical activity. Healthy, non-smoking coffee-drinkers (n 214) were asked to change their coffee habits in a controlled clinical trial on the metabolic effects of coffee. The participants were asked to maintain their usual dietary habits. Self-perceived changes in diet and physical activity during the 6-week intervention period were assessed at the end. In the analyses, the participants were rearranged into groups reflecting the difference in coffee intake during the trial as compared with habitual intake. Associations with changes in food intake or physical activity were analysed by Spearman rank correlation. Changes in intake of 'chocolate, sweets' (r 0.179, P<0.05), 'cakes, sweet biscuits, pastry' (r 0.306, P<0.001), and 'jam' r 0.198, P<0.05) showed positive associations with change in coffee intake during the trial. Negative associations were found for 'dishes with fish' (r -0.204, P<0.01) and many of the drinks as well as with physical activity (r -0.164, P<0.05). Induced changes in coffee intake seem to alter ad libitum intake of several foods. The recognized associations between health behaviours may have physiological explanations.     

Both longer oral sensory exposure to and higher intensity of saltiness decrease ad libitum food intake in healthy normal-weight men

Orosensory exposure to sweetness has been shown to be important in satiation, whereas the effect of exposure to a salty taste on satiation is not known. The primary objective was to investigate the effect of orosensory exposure time to and intensity of saltiness in soup on ad libitum intake. The secondary objective was to investigate the effect of intensity on bite size. Fifty-five healthy men consumed ad libitum from both a low-salt (LS) and a high-salt (HS) creamy tomato soup in 2 exposure time conditions ("long" and "short") and a free condition ("free"). Bites were administered and controlled via a pump. In the long condition, bites of 5 g were administered in 2 s at intervals of 5 s (exposure time: 24 s/min). In the short condition, bites of 15 g were administered in 3 s at intervals of 15 s (exposure time: 12 s/min). The eating rate was equal in the long and short conditions (60 g/min). In the free condition, participants adjusted their bite sizes at intervals of 15 s. The short condition resulted in ~34% higher ad libitum intake compared to the long condition (P < 0.001); there was no interaction with intensity. Ad libitum intake of HS soup was ~9% lower than LS soup (P < 0.001). The free condition showed that HS soup was consumed with smaller bite sizes during the first half of the intake period (P < 0.05). Longer orosensory exposure and higher saltiness intensity both decreased food intake, although orosensory exposure had more impact than intensity. Prolonging the orosensory exposure per food unit may be helpful to reduce food intake.     

An ad libitum, very low-fat diet results in weight loss and changes in nutrient intakes in postmenopausal women

OBJECTIVES: To determine whether a very low-fat diet (<15% of energy intake) consumed ad libitum during an 8-month period can achieve weight loss of 5% to 10% of initial body weight while still providing adequate intakes of other essential nutrients. DESIGN: Longitudinal, 8-month, ad libitum, free living, very low-fat diet trial. SUBJECTS: Fifty-four of the sixty-four healthy postmenopausal women recruited completed the entire study (age 59+/-8 years, BMI=29.6+/-6.3). Twenty-four of these women used hormone replacement therapy, thirty women did not. INTERVENTION: Weekly sessions aimed at teaching and reinforcing a very low-fat intake diet for eight months. MAIN: outcome measures Body weight, percent body fat, waist-to-hip ratio, resting energy expenditure, respiratory quotient, and nutrient intakes derived from 7-day food records at the beginning and at 2, 4, 6, and 8 months of the study.Statistical analysis performed Repeated measures analysis of variance and Tukey post hoc analysis were used to analyze significant differences in mean data (P<.05). RESULTS: Fat intake decreased from 33.2+/-7.5% to 11+/-4% over the 8-month intervention period (P<.00001). Weight loss was 6.0 kg+/- 4.2 kg (P<.000038), an 8% weight change, and decrease in percent body fat of 2.7%+/-0.2% (P< or =.000046). Weight correlated better with the self-reported fat intake (r=0.321, P<.01) than the energy intake (r=0.263, P<.05) at baseline. Fiber intake increased from 16 g+/-0.6 g to 23 g+/-0.2 g (P<.0005). All micronutrient intakes remained at or above preintervention ranges, except for a decrease in vitamin E intake from 8.1 mg+/-4.0 mg to 3.7 mg+/-1.1 mg (P<.0005) on the very low-fat diet and linoleic acid from 6.3%+/-1.5% to 2.5%+/-0.7% (P<.000001) with no significant reduction in linolenic acid. Hormone replacement was not associated with the amount of weight loss. APPLICATIONS: This study demonstrates that adherence to a very low-fat diet consumed ad libitum causes weight loss in the 5% to 10% range and a reduction of body fat. These reductions, along with the observed decreases in fat intake, are associated with improved health outcomes. Because of the decreased vitamin E and n-3 fatty acid intake, emphasis on foods high in these nutrients may need to be encouraged for those consuming a very low-fat diet.     

Arousal,physical activity,and energy balance in eating and body weight and shape disorders

It is argued that psychopathologically driven body weight and shape disorders in the female are intimately bound up with experience of the physical parameters of the self, their perceived implications for self-esteem on the one hand, and survival on the other. The avoidance of turmoil may lead to profound distortions of normal growth processes and resting metabolism, creating a worsening of the psychological problem.     

A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations

BACKGROUND: Ad libitum, low-carbohydrate diets decrease caloric intake and cause weight loss. It is unclear whether these effects are due to the reduced carbohydrate content of such diets or to their associated increase in protein intake. OBJECTIVE: We tested the hypothesis that increasing the protein content while maintaining the carbohydrate content of the diet lowers body weight by decreasing appetite and spontaneous caloric intake. DESIGN: Appetite, caloric intake, body weight, and fat mass were measured in 19 subjects placed sequentially on the following diets: a weight-maintaining diet (15% protein, 35% fat, and 50% carbohydrate) for 2 wk, an isocaloric diet (30% protein, 20% fat, and 50% carbohydrate) for 2 wk, and an ad libitum diet (30% protein, 20% fat, and 50% carbohydrate) for 12 wk. Blood was sampled frequently at the end of each diet phase to measure the area under the plasma concentration versus time curve (AUC) for insulin, leptin, and ghrelin. RESULTS: Satiety was markedly increased with the isocaloric high-protein diet despite an unchanged leptin AUC. Mean (+/-SE) spontaneous energy intake decreased by 441 +/- 63 kcal/d, body weight decreased by 4.9 +/- 0.5 kg, and fat mass decreased by 3.7 +/- 0.4 kg with the ad libitum, high-protein diet, despite a significantly decreased leptin AUC and increased ghrelin AUC. CONCLUSIONS: An increase in dietary protein from 15% to 30% of energy at a constant carbohydrate intake produces a sustained decrease in ad libitum caloric intake that may be mediated by increased central nervous system leptin sensitivity and results in significant weight loss. This anorexic effect of protein may contribute to the weight loss produced by low-carbohydrate diets.     

Anterior cingulate taste activation predicts ad libitum intake of sweet and savory drinks in healthy, normal-weight men

After food consumption, the motivation to eat (wanting) decreases and associated brain reward responses change. Wanting-related brain responses and how these are affected by consumption of specific foods are ill documented. Moreover, the predictive value of food-induced brain responses for subsequent consumption has not been assessed. We aimed to determine the effects of consumption of sweet and savory foods on taste activation in the brain and to assess how far taste activation can predict subsequent ad libitum intake. Fifteen healthy men (age: 27 ± 2 y, BMI: 22.0 ± 1.5 kg/m2) participated in a randomized crossover trial. After a >3-h fast, participants were scanned with the use of functional MRI before and after consumption of a sweet or savory preload (0.35 L fruit or tomato juice) on two occasions. After the scans, the preload juice was consumed ad libitum. During scanning, participants tasted the juices and rated their pleasantness. Striatal taste activation decreased after juice consumption, independent of pleasantness. Sweet and savory taste activation were not differentially affected by consumption. Anterior cingulate taste activation predicted subsequent ad libitum intake of sweet (r = -0.78; P < 0.001(uncorrected)) as well as savory juice (r = -0.70; P < 0.001(uncorrected)). In conclusion, we showed how taste activation of brain reward areas changes following food consumption. These changes may be associated with the food's physiological relevance. Further, the results suggest that anterior cingulate taste activation reflects food-specific satiety. This extends our understanding of the representation of food specific-appetite in the brain and shows that neuroimaging may provide objective and more accurate measures of food motivation than self-report measures.     

Role of protein and carbohydrate sources on acute appetite responses in lean and overweight men

Dietary protein induces greater satiety compared with carbohydrate in lean subjects, which may involve appetite-regulatory gut hormones. Little is known about the duration of effect, influence of protein and carbohydrate source and relevance to non-lean individuals. We compared the effect of various dietary proteins and carbohydrates on post-prandial appetite ratings, ad libitum energy intake (EI) and appetite hormones in lean and overweight men. Three randomised double-blinded cross-over studies examined appetite response (appetite ratings, ghrelin, glucagon-like peptide-1 (GLP-1) and cholecystokinin) to liquid preloads over three to four hours followed by a buffet meal to assess ad libitum EI. The 1-MJ preloads contained ∼55 g of protein (whey, casein, soy and gluten), carbohydrate (glucose, lactose and fructose) or combined whey/fructose. EI was 10% higher following glucose preloads compared with protein preloads, observed at three hours but not four hours. Protein ingestion was followed by prolonged elevation of cholecystokinin and GLP-1 (two hours) and suppression of ghrelin (three to four hours) compared with glucose and independent of protein type. Replacing some whey with fructose attenuated the effect of protein on these hormones. Treatment effects on EI and appetite hormones were independent of bodyweight status, despite higher GLP-1 and lower ghrelin in overweight subjects. Protein-rich liquid preloads reduce EI over three hours in overweight men compared with glucose. These findings suggest a potential application for protein-rich drinks and/or foods to facilitate reduced EI. Future studies should explore additional dietary manipulations that may enhance this relationship, and confirm these effects within the context of energy-restricted dietary patterns.     

Effect of long-term high-fat feeding on energy balance and liver oxidative activity in rats

The purpose of this work was to study the effect of early long-term high-fat feeding on energy balance and liver oxidative activity. To this end, rats aged about 30 d were fed a high-fat or a low-fat diet for 15, 30 or 60 d. Full energy balance and energy partitioning measurements were carried out. In addition, we measured hepatic mitochondrial and peroxisomal oxidative capacities. Serum levels of free triiodothyronine (T3) and leptin were also determined. Rats fed a high-fat diet showed an increase in metabolizable energy intake as well as in energy expenditure, while lipid gain over the whole period was lower than that expected due to a decrease in metabolic efficiency. An increase in serum free T3 levels was also found in rats fed a high-fat diet after 15 and 30 d. Statistically significant correlations between serum leptin levels and body fat mass were found after 15, 30 and 60 d of high-fat feeding. Finally, no variation in hepatic mitochondrial and peroxisomal fatty acid oxidation capacity was found in rats fed a high-fat diet for 15, 30 or 60 d. In conclusion, the results of the present study show that young Wistar rats fed a high-fat diet for up to 60 d are able to counteract, at least in part, obesity development.     

Effect of short-duration physical activity and ventilation threshold on subjective appetite and short-term energy intake in boys

The purpose of this investigation was twofold: (1) to examine the role of low- to moderate-intensity, short-duration physical activity on subjective appetite and (2) to identify the role of and associations between ventilation threshold (VeT) and energy intake at a pizza lunch 30 min after glucose and whey protein drinks in normal weight boys. In 14 boys (age: 12.5+/-0.4 years) subjective appetite was measured before and after a 12 min walking protocol designed to determine physical fitness based on the VeT. On a separate occasion food intake (FI) and subjective appetite were measured in response to sweetened preloads of either a SPLENDA Sucralose control, glucose or whey protein made up to 250 ml with water, given in random order to each boy, 2h after a standardized breakfast. Subjective average appetite and prospective food consumption scores increased after physical activity. VeT was positively associated with FI at a pizza lunch consumed 30 min after glucose and whey protein drinks. Glucose and whey protein reduced FI similarly at lunch compared with control. In conclusion, appetite is increased by low- to moderate-intensity, short-duration physical activity and FI following glucose and protein preloads is positively associated with fitness levels in boys.     

Long-term effect of physical activity on energy balance and body composition.

We studied the effect of an increase in physical activity on energy balance and body composition without interfering with energy intake (EI). Sixteen women and sixteen men, aged 28-41 years, body mass index 19.4-26.4 kg/m2, not participating in any sport before the start of the experiment, prepared to run a half-marathon competition after 44 weeks. Measurements of body composition, EI and energy expenditure (EE) were performed before (0 weeks), and 8, 20, and 40 weeks after the start of training. Body composition was measured with hydrodensitometry and isotope dilution, and EI with a 7 d dietary record. EE was measured overnight in a respiration chamber (sleeping metabolic rate (SMR)) and in a number of subjects over 2-week intervals with doubly-labelled water (average daily metabolic rate (ADMR)). ADMR showed an average increase of 30% in both sexes from the start of training onwards while SMR tended to decrease. EI showed a tendency to drop from week 20 to week 40 in the men and a tendency to increase from week 20 to week 40 in the women. Body mass (BM) did not change in both sexes until the observation at 40 weeks when the median value of the change in men was -1.0 kg (P < 0.01; Wilcoxon signed-rank) while the corresponding change of -0.9 kg in the women was not statistically significant. Body composition changes were most pronounced in men as well. Based on changes in BM, body volume and total body water, men lost 3.8 kg fat mass (FM) (P < 0.001; Wilcoxon signed-rank) and gained 1.6 kg protein mass (P < 0.01; Wilcoxon signed-rank) while the corresponding changes in women were 2.0 kg (P < 0.05; Wilcoxon signed-rank) and 1.2 kg (P < 0.05; Wilcoxon signed-rank). In men the loss of FM was positively correlated with the initial percentage body fat (Pearson r 0.92, P < 0.001). In conclusion, body fat can be reduced by physical activity although women tend to compensate for the increased EE with an increased EI, resulting in a smaller effect on BM and FM compared with men.     

Carbohydrates, appetite and feeding behavior in humans

The view of carbohydrates in relation to obesity has changed over the past few decades from being conducive to overconsumption and weight gain to being protective. This article reviews the mechanisms by which carbohydrate is purported to protect against weight gain. Although carbohydrate is metabolized and stored in the body less efficiently than fat, when de novo lipogenesis is invoked on very high carbohydrate diets, the beneficial effect on energy balance is likely to be minimal when typical high fat Western diets are consumed. However, it has been suggested that high carbohydrate foods may influence energy balance by reducing food intake through greater satiety effects, reducing energy density and displacing fat from the diet-the fat-sugar seesaw effect. To date, there seem to be few differences between sugars and starches on satiety and energy intake, but few studies have examined this. Some reduced-fat, and, therefore, higher carbohydrate, foods are highly energy dense. High carbohydrate foods do not necessarily have a low energy density. Evidence from recent studies suggests that adding carbohydrate, and especially sugar, to the diet neither displaces fat from the diet nor protects against elevated energy intake. Although it is easier to overeat on high fat than low fat foods, simply replacing fat with carbohydrate in the diet may not be as protective against overconsumption as the energy density or fat-sugar seesaw arguments suggest.