Effects of dietary fibre on behaviour and satiety in pigs

During the past decades there has been considerable interest in the use of dietary fibre in both animal and human nutrition. In human subjects dietary fibre has been studied intensively for possible effects on body-weight management and health. In animal nutrition the interest in dietary fibre has increased because it can be used as a cheap source of energy and because of its potential to improve animal welfare and reduce abnormal (mainly stereotypic) behaviour. Animal welfare is impaired if the diet does not provide sufficient satiety, combined with an environment that does not meet specific behavioural requirements related to natural feeding habits (e.g. rooting in pigs). A considerable proportion of the behavioural effects of dietary fibre are thought to be related to reduced feeding motivation. It has been hypothesized that: (1) bulky fibres increase satiety and thereby decrease physical activity and stereotypic behaviours immediately following a meal in pigs; (2) fermentable fibres prolong postprandial satiety and thereby reduce physical activity and appetitive behaviours for many hours after a meal. The validity of these hypotheses is examined by considering published data. In sows dietary fibres (irrespective of source) reduce stereotypic self-directed behaviours and substrate-directed behaviours, and to a lesser extent overall physical activity, indicating enhanced satiety shortly after a meal. Furthermore, fermentable dietary fibre reduces substrate-directed behaviour in sows and physical activity in sows and growing pigs for many hours after a meal. Evidence of long-term effects of poorly-fermentable fibre sources is inconclusive. The findings suggest that highly-fermentable dietary fibres have a higher potential to prolong postprandial satiety.     

Satiation, satiety and their effects on eating behaviour

• 2.1 Physiological mechanisms of satiation
  • 2.1.1 Gastric mechanisms of satiation
  • 2.1.2 Intestinal mechanisms of satiation
• 2.2 Physiological mechanisms of satiety
  • 2.2.1 Gut hormones – episodic signals of satiety
  • 2.2.2 Tonic satiety signals
• 2.3 The integration of satiety signals in the brain
  • 2.3.1 Anorexigenic pathways in the hypothalamus
  • 2.3.2 Orexigenic pathways in the hypothalamus
  • 2.3.3 Other areas of the brain involved in satiation and satiety
  • 2.3.4 Reward pathways

3 Measuring satiation and satiety

• 3.1 Measuring satiation
• 3.2 Measuring satiety
  • 3.2.1 Free living vs. laboratory studies
  • 3.2.2 Preload studies
  • 3.2.3 Self‐reported measures of satiety
  • 3.2.4 Measuring food intake
  • 3.2.5 Quantifying satiety
• 3.3 Confounders in satiety research
  • 3.3.1 Physiological confounders
  • 3.3.2 Behavioural confounders

4 The effects of foods and drinks on satiety

• 4.1 Protein and satiety
• 4.2 Carbohydrates and satiety
• 4.3 Fibre and satiety
• 4.4 Intense sweeteners and satiety
• 4.5 Fat and satiety
• 4.6 Liquids and satiety
• 4.7 Alcohol and satiety
• 4.8 Energy density and satiety

5 The effect of external factors on satiation and satiety

• 5.1 Palatability
• 5.2 Variety
• 5.3 Portion size
• 5.4 Sleep
• 5.5 Physical activity
• 5.6 Television viewing and other distractions
• 5.7 Social situations

6 Satiation, satiety and weight control

• 6.1 Obesity genes and satiety
• 6.2 Physiological differences in satiation and satiety responses in obese people
• 6.3 Behavioural differences in the response to satiation and satiety in obesity

7 Conclusions

Summary

In the context of the rising prevalence of obesity around the world, it is vital to understand how energy balance and bodyweight are controlled. The ability to balance energy intake and expenditure is critical to survival, and sophisticated physiological mechanisms have developed in order to do this, including the control of appetite. Satiation and satiety are part of the body's appetite control system and are involved in limiting energy intake. Satiation is the process that causes one to stop eating; satiety is the feeling of fullness that persists after eating, suppressing further consumption, and both are important in determining total energy intake. Satiation and satiety are controlled by a cascade of factors that begin when a food or drink is consumed and continues as it enters the gastrointestinal tract and is digested and absorbed. Signals about the ingestion of energy feed into specific areas of the brain that are involved in the regulation of energy intake, in response to the sensory and cognitive perceptions of the food or drink consumed, and distension of the stomach. These signals are integrated by the brain, and satiation is stimulated. When nutrients reach the intestine and are absorbed, a number of hormonal signals that are again integrated in the brain to induce satiety are released. In addition to these episodic signals, satiety is also affected by fluctuations in hormones, such as leptin and insulin, which indicate the level of fat storage in the body. Satiation and satiety can be measured directly via food intake or indirectly via ratings of subjective sensations of appetite. The most common study design when measuring satiation or satiety over a short period is using a test preload in which the variables of interest are carefully controlled. This is followed by subjects rating aspects of their appetite sensations, such as fullness or hunger, at intervals and then, after a predetermined time interval, a test meal at which energy intake is measured. Longer‐term studies may provide foods or drinks of known composition to be consumed ad libitum and use measures of energy intake and/or appetite ratings as indicators of satiety. The measurement of satiation and satiety is complicated by the fact that many factors besides these internal signals may influence appetite and energy intake, for example, physical factors such as bodyweight, age or gender, or behavioural factors such as diet or the influence of other people present. For this reason, the majority of studies on satiation and satiety take place in a laboratory, where confounders can be controlled as much as possible, and are, therefore, of short duration. It is possible for any food or drink to affect appetite, and so it is important to determine whether, for a given amount of energy, particular variables have the potential to enhance or reduce satiation or satiety. A great deal of research has been conducted to investigate the effect of different foods, drinks, food components and nutrients on satiety. Overall, the characteristic of a food or drink that appears to have the most impact on satiety is its energy density. That is the amount of energy it contains per unit weight (kJ/g, kcal/g). When energy density is controlled, the macronutrient composition of foods does not appear to have a major impact on satiety. In practice, high‐fat foods tend to have a higher energy density than high‐protein or high‐carbohydrate foods, and foods with the highest water content tend to have the lowest energy density. Some studies have shown that energy from protein is more satiating than energy from carbohydrate or fat. In addition, certain types of fibre have been shown to enhance satiation and satiety. It has been suggested that energy from liquids is less satiating then energy from solids. However, evidence for this is inconsistent, and it may be the mode of consumption (i.e. whether the liquid is perceived to be a food or drink) that influences its effect on satiety. Alcohol appears to stimulate energy intake in the short‐term, and consuming energy from alcohol does not appear to lead to a subsequent compensatory reduction in energy intake. The consumption of food and drink to provide energy is a voluntary behaviour, and, despite the existence of sophisticated physiological mechanisms to match intake to requirements, humans often eat when sated and sometimes refrain from eating when hungry. Thus, there are numerous influences on eating behaviour beyond satiation and satiety. These include: the portion size, appeal, palatability and variety of foods and drinks available; the physiological impact on the body of physical activity and sleep; and other external influences such as television viewing and the effect of social situations. Because satiation and satiety are key to controlling energy intake, inter‐individual differences in the strength of these signals and responsiveness to their effects could affect risk of obesity. Such differences have been observed at a genetic, physiological and behavioural level and may be important to consider in strategies to prevent or treat obesity. Overall, it is clear that, although the processes of satiation and satiety have the potential to control energy intake, many individuals override the signals generated. Hence, in such people, satiation and satiety alone are not sufficient to prevent weight gain in the current obesogenic environment. Knowledge about foods, ingredients and dietary patterns that can enhance satiation and satiety is potentially useful for controlling bodyweight. However, this must be coupled with an understanding of the myriad of other factors that influence eating behaviour, in order to help people to control their energy intake.     

Dietary fibres in the regulation of appetite and food intake. Importance of viscosity

Dietary fibres have many functions in the diet, one of which may be to promote control of energy intake and reduce the risk of developing obesity. This is linked to the unique physico-chemical properties of dietary fibres which aid early signalling of satiation and prolonged or enhanced sensation of satiety. Particularly the ability of some dietary fibres to increase viscosity of intestinal contents offers numerous opportunities to affect appetite regulation. Few papers on the satiating effect of dietary fibres include information on the physico-chemical characteristics of the dietary fibres being tested, including molecular weight and viscosity. For viscosity to serve as a proxy for soluble dietary fibres it is essential to have an understanding of individual dietary fibre viscosity characteristics. The goal of this paper is to provide a brief overview on the role of dietary fibres in appetite regulation highlighting the importance of viscosity.     

Pulse grain consumption and obesity: effects on energy expenditure, substrate oxidation, body composition, fat deposition and satiety

Pulses have been identified as important components of a healthy diet. Assessment of pulse grains' nutritional composition alongside data from available preclinical and clinical trials suggests that pulses can modulate biological processes that lead to obesity. Components of pulse grains, including pulse-derived fibre and resistant starch, have been shown to alter energy expenditure, substrate trafficking and fat oxidation as well as visceral adipose deposition. Although mechanistic studies are scarce, studies have indicated that fibres found in pulses can have an impact on the expression of genes that modulate metabolism. Arginine and glutamine may produce thermogenic effects as major components of pulse grain proteins. Finally, evidence suggests that pulse-derived fibres, trypsin inhibitors and lectins may reduce food intake by inducing satiety via facilitating and prolonging cholecystokinin secretion. Nonetheless, the aforementioned data remain controversial and associations between dietary pulse grains and energy intake require further study. Given the available evidence, it can be concluded that pulses could be useful as functional foods and food ingredients that combat obesity.     

Strategies for healthy weight loss: from vitamin C to the glycemic response

America is experiencing a major obesity epidemic. The ramifications of this epidemic are immense since obesity is associated with chronic metabolic abnormalities such as insulin resistance, dyslipidemia, and heart disease. Reduced physical activity and/or increased energy intakes are important factors in this epidemic. Additionally, a genetic susceptibility to obesity is associated with gene polymorphisms affecting biochemical pathways that regulate fat oxidation, energy expenditure, or energy intake. However, these pathways are also impacted by specific foods and nutrients. Vitamin C status is inversely related to body mass. Individuals with adequate vitamin C status oxidize 30% more fat during a moderate exercise bout than individuals with low vitamin C status; thus, vitamin C depleted individuals may be more resistant to fat mass loss. Food choices can impact post-meal satiety and hunger. High-protein foods promote postprandial thermogenesis and greater satiety as compared to high-carbohydrate, low-fat foods; thus, diet regimens high in protein foods may improve diet compliance and diet effectiveness. Vinegar and peanut ingestion can reduce the glycemic effect of a meal, a phenomenon that has been related to satiety and reduced food consumption. Thus, the effectiveness of regular exercise and a prudent diet for weight loss may be enhanced by attention to specific diet details.     

Biomarkers of satiation and satiety

This review's objective is to give a critical summary of studies that focused on physiologic measures relating to subjectively rated appetite, actual food intake, or both. Biomarkers of satiation and satiety may be used as a tool for assessing the satiating efficiency of foods and for understanding the regulation of food intake and energy balance. We made a distinction between biomarkers of satiation or meal termination and those of meal initiation related to satiety and between markers in the brain [central nervous system (CNS)] and those related to signals from the periphery to the CNS. Various studies showed that physicochemical measures related to stomach distension and blood concentrations of cholecystokinin and glucagon-like peptide 1 are peripheral biomarkers associated with meal termination. CNS biomarkers related to meal termination identified by functional magnetic resonance imaging and positron emission tomography are indicators of neural activity related to sensory-specific satiety. These measures cannot yet serve as a tool for assessing the satiating effect of foods, because they are not yet feasible. CNS biomarkers related to satiety are not yet specific enough to serve as biomarkers, although they can distinguish between extreme hunger and fullness. Three currently available biomarkers for satiety are decreases in blood glucose in the short term (<5 min), which have been shown to be involved in meal initiation; leptin changes during longer-term (>2-4 d) negative energy balance; and ghrelin concentrations, which have been implicated in both short-term and long-term energy balance. The next challenge in this research area is to identify food ingredients that have an effect on biomarkers of satiation, satiety, or both. These ingredients may help consumers to maintain their energy intake at a level consistent with a healthy body weight.     

Strategies for Healthy Weight Loss: From Vitamin C to the Glycemic Response

Abstract America is experiencing a major obesity epidemic. The ramifications of this epidemic are immense since obesity is associated with chronic metabolic abnormalities such as insulin resistance, dyslipidemia, and heart disease. Reduced physical activity and/or increased energy intakes are important factors in this epidemic. Additionally, a genetic susceptibility to obesity is associated with gene polymorphisms affecting biochemical pathways that regulate fat oxidation, energy expenditure, or energy intake. However, these pathways are also impacted by specific foods and nutrients. Vitamin C status is inversely related to body mass. Individuals with adequate vitamin C status oxidize 30% more fat during a moderate exercise bout than individuals with low vitamin C status; thus, vitamin C depleted individuals may be more resistant to fat mass loss. Food choices can impact post-meal satiety and hunger. High-protein foods promote postprandial thermogenesis and greater satiety as compared to high-carbohydrate, low-fat foods; thus, diet regimens high in protein foods may improve diet compliance and diet effectiveness. Vinegar and peanut ingestion can reduce the glycemic effect of a meal, a phenomenon that has been related to satiety and reduced food consumption. Thus, the effectiveness of regular exercise and a prudent diet for weight loss may be enhanced by attention to specific diet details.     

Lack of energy compensation over 4 days when white button mushrooms are substituted for beef

Increasing intake of low energy density (ED) foods in place of high ED foods has been proposed as a strategy for preventing or treating obesity. This study investigated how substituting mushrooms for beef in a test lunch affected energy intake, fat intake, palatability, appetite, satiation and satiety in normal weight, overweight and obese adults. Each subject consumed a total of eight test lunches in our lab over two consecutive weeks. The order of presentation of four consecutive meat lunches and four consecutive mushroom lunches was randomized. Energy content of meat and mushroom lunches varied (783 kcal versus 339 kcal), while volume was held constant. Energy intakes were significantly higher during meat lunches than mushroom lunches (730+/-7.9 kcal versus 310+/-5.8 kcal). Subjects exhibited only partial compensation (11.4+/-12.0%) for this difference over 4 days. Total daily energy intake and fat intake were significantly greater in the meat condition than in the mushroom condition, while ratings of palatability, appetite, satiation and satiety did not differ significantly. These results suggest that substituting low ED foods for high ED foods in otherwise similar recipes can be an effective method for reducing daily energy and fat intake.     

Current and emerging concepts on the role of peripheral signals in the control of food intake and development of obesity

The gastrointestinal peptides are classically known as short-term signals, primarily inducing satiation and/or satiety. However, accumulating evidence has broadened this view, and their role in long-term energy homeostasis and the development of obesity has been increasingly recognised. In the present review, the recent research involving the role of satiation signals, especially ghrelin, cholecystokinin, glucagon-like peptide 1 and peptide YY, in the development and treatment of obesity will be discussed. Their activity, interactions and release profile vary constantly with changes in dietary and energy influences, intestinal luminal environment, body weight and metabolic status. Manipulation of gut peptides and nutrient sensors in the oral and postoral compartments through diet and/or changes in gut microflora or using multi-hormone 'cocktail' therapy are among promising approaches aimed at reducing excess food consumption and body-weight gain.     

Mechanisms of cholesterol-lowering effects of dietary insoluble fibres: relationships with intestinal and hepatic cholesterol parameters

Fibres with a range of abilities to perturb cholesterol homeostasis were used to investigate how the serum cholesterol-lowering effects of insoluble dietary fibres are related to parameters of intestinal cholesterol absorption and hepatic cholesterol homeostasis in mice. Cholestyramine, chitosan and cellulose were used as examples of fibres with high, intermediate and low bile acid-binding capacities, respectively. The serum cholesterol levels in a control group of mice fed a high fat/high cholesterol (HFHC) diet for 3 weeks increased about 2-fold to 4.3 mm and inclusion of any of these fibres at 7.5 % of the diet prevented this increase from occurring. In addition, the amount of cholesterol accumulated in hepatic stores due to the HFHC diet was reduced by treatment with these fibres. The three kinds of fibres showed similar hypocholesterolaemic activity; however, cholesterol depletion of liver tissue was greatest with cholestyramine. The mechanisms underlying the cholesterol-lowering effect of cholestyramine were (1) decreased cholesterol (food) intake, (2) decreased cholesterol absorption efficiency, and (3) increased faecal bile acid and cholesterol excretion. The latter effects can be attributed to the high bile acid-binding capacity of cholestyramine. In contrast, incorporation of chitosan or cellulose in the diet reduced cholesterol (food) intake, but did not affect either intestinal cholesterol absorption or faecal sterol output. The present study provides strong evidence that above all satiation and satiety effects underlie the cholesterol-lowering properties of insoluble dietary fibres with moderate or low bile acid-binding capabilities.     

Food texture and the satiety cascade

Using the satiety cascade model as a framework, this paper describes how food texture can influence the strength and duration of sensory, cognitive and post‐ingestive signals that determine when a meal ends (satiation) and the inhibition of appetite between meals (satiety). The influence of food texture on oro‐sensory exposure time, expectations about the satiating effect of a food and processing of food in the gastrointestinal system is considered, as well how the interaction of these processes may impact on the overall experience of satiety. This body of work suggests that texture is one element of a food's flavour profile which could be a candidate for manipulation in the development of ‘high‐satiety’ foods.     

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

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

Faecal bulking efficacy of Australasian breakfast cereals

Faecal bulk may play an important role in preventing a range of disorders of the large bowel, but as yet there is little information available on the relative faecal bulking capacities of various foods. Breakfast cereals are often promoted as a good source of potential bulk for 'inner health' because they provide dietary fibre, but their relative abilities to provide faecal bulk per se have not been described. The faecal bulking efficacy of 28 representative Australasian breakfast cereals was therefore measured. A rat model developed for the purpose, and shown to give similar responses as humans to cereal fibres, was used to measure faecal bulking efficacy as increases in fully hydrated faecal weight/100 g diet, based on precise measurements of food intake, faecal dry matter output and faecal water-holding capacity (g water held without stress/g faecal dry matter). Compared to a baseline diet containing 50% sucrose, increments in hydrated faecal weight due to 50% breakfast cereal ranged from slightly negative (Cornflakes, -2 g/100 g diet) to about 80 g/100 g diet (San Bran). Most breakfast cereals increased hydrated faecal weight by between 10 and 20 g/100 g diet from a baseline of 21 +/- 1.5 g/100 g diet, but four products containing high levels of wheat bran had an exceptionally large impact on hydrated faecal weight (increment > 20 g/100 g diet), and the changes resulted more from relative changes in dry matter output than in faecal water retention/gram. However, as faecal water retention was about 2.5 g water/g faecal dry matter on average, increases in dry matter represented large increases in faecal water load. Faecal bulking indices (FBI) for most of the breakfast cereals were less than 20 (wheat bran = 100). The content of wheat bran equivalents for faecal bulk (WBE(fb)) in the breakfast cereals was calculated from FBI. Most breakfast cereals contributed, per serve, less than 10% of a theoretical daily reference value for faecal bulk (DRV(fb) = 63 WBE(fb)/day), which was based on data from human clinical trials and dietary fibre recommendations. Based on the WBE(fb) contribution/serving that would be required to meet the DRV(fb) from the number of servings of dietary fibre sources in the CSIRO 12345+ food and nutrition plan, the results suggest that although some high bran breakfast cereals may contribute substantially to, and many are reasonable sources of, faecal bulk, for most of them, one or two servings at breakfast cannot be relied on to effectively redress shortfalls in faecal bulk elsewhere in the diet.     

Whole grain consumption and weight gain: a review of the epidemiological evidence,potential mechanisms and opportunities for future research

The epidemiological data that directly examine whole grain v. refined grain intake in relation to weight gain are sparse. However, recently reported studies offer insight into the potential role that whole grains may play in body-weight regulation due to the effects that the components of whole grains have on hormonal factors, satiety and satiation. In both clinical trials and observational studies the intake of whole-grain foods was inversely associated with plasma biomarkers of obesity, including insulin, C-peptide and leptin concentrations. Whole-grain foods tend to have low glycaemic index values, resulting in lower postprandial glucose responses and insulin demand. High insulin levels may promote obesity by altering adipose tissue physiology and by enhancing appetite. The fibre content of whole grains may also affect the secretion of gut hormones, independent of glycaemic response, that may act as satiety factors. Future studies may examine whether whole grain intake is directly related to body weight, and whether the associations are primarily driven by components of the grain, including dietary fibre, bran or germ.     

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.     

High-level dietary fibre up-regulates colonic fermentation and relative abundance of saccharolytic bacteria within the human faecal microbiota in vitro

Background

Health authorities around the world advise citizens to increase their intake of foods rich in dietary fibre because of its inverse association with chronic disease. However, a few studies have measured the impact of increasing mixed dietary fibres directly on the composition of the human gut microbiota.

Aims of the study

We studied the impact of high-level mixed dietary fibre intake on the human faecal microbiota using an in vitro three-stage colonic model.

Methods

The colonic model was maintained on three levels of fibre, a basal level of dietary fibre, typical of a Western-style diet, a threefold increased level and back to normal level. Bacterial profiles and short chain fatty acids concentrations were measured.

Results

High-level dietary fibre treatment significantly stimulated the growth of Bifidobacterium, Lactobacillus-Enterococcus group, and Ruminococcus group (p?Faecalibacterium prausnitzii in vessel 1 mimicking the proximal colon (p?p?Conclusions This study shows that high-level mixed dietary fibre intake can up-regulate both colonic fermentation and the relative abundance of saccharolytic bacteria within the human colonic microbiota. Considering the important role of short chain fatty acids in regulating human energy metabolism, this study has implications for the health-promoting potential of foods rich in dietary fibres.     

Satiety from rice-based, wheat-based and rice-pulse combination preparations

The satiety values of six breakfast items commonly consumed in India were determined on the basis of area under the curve. A repeated measures design was used wherein energy intake, hunger, and satiety scores were assessed for one rice-based, three wheat-based and a rice-pulse fermented preparation, using white bread as the reference. Subjects were provided equi-caloric portions of the six breakfast items on separate occasions, and satiety ratings were recorded every 15 min over a 120 min period, after which time they were free to consume whatever they desired. Satiety scores were in the order of fermented cereal-pulse preparation> savoury broken wheat preparation>whole wheat flour flat bread>savoury semolina preparation> savoury rice flakes preparation>white bread standard. Among the various factors examined for their influence on satiety scores, fibre content, energy density and cooked weight of the food items positively influenced satiety scores. Neither fat nor carbohydrate content showed any correlation with satiety scores. These data indicate that isoenergetic portions of various foods influence satiety to different extents. Thus results suggest that consumption of high protein, high fibre and foods with greater water/volume leading to low energy density may be effective in delaying the return of hunger.     

Fibre,satiety and insulin -a new approach to overnutrition and obesity

Overnutrition or energy imbalance is a major problem in civilised communities. The energy potential of food depends not only on its energy content but also on its satiating capacity. In removing fibre from carbohydrate foods man creates foods which are artificially low in satiety. This has been demonstrated by compariso ns of equivalent meals of apple juice and whole apples and of white and wholemeal bread. Simply disruptit1g fibre by turning apples into a purée also reduces their satiety potential. Insulin is a hormone which favours the synthesis and deposition of fat. Fibre-depleted apple juice evokes a greater insulin response than whole apples, while purée has an intermediate effect. Refined carbohydrate probably causes hyperinsulinism by being readily and rapidly absorbed. This provides a further link between such foods and obesity, as well as a possible mechanism for the causation of diabetes and atherosclerosis.     

Effects of a controlled diet supplemented with chickpeas on serum lipids, glucose tolerance, satiety and bowel function

OBJECTIVE: To compare the effect of a diet supplemented with chickpeas to a wheat-based diet of similar fibre content on serum lipids, glucose tolerance, satiety and bowel function. A third, lower-fibre wheat diet provided further information on dietary fibre quantity and bowel function and satiety. METHOD: Twenty-seven free-living adults followed two randomized, crossover dietary interventions each of five weeks duration. The chickpea diet included canned drained chickpeas, bread and shortbread biscuits containing 30% chickpea flour. The wheat diet included high-fibre wheat breakfast cereals and wholemeal bread. The diets were isoenergetic to the participants' usual diet, matched for macronutrient content and controlled for dietary fibre. Following on from the second randomised intervention, a sub-group of 18 participants underwent a third, isoenergetic lower-fibre wheat diet that included low-fibre breakfast cereals and bread. RESULTS: Repeated measures ANOVA revealed reductions in serum TC of 0.25 mmol/L (p < 0.01) and LDL-C of 0.20 mmol/L (p = 0.02) following the chickpea diet compared to the wheat. An unintended significant increase in PUFA and corresponding decrease in MUFA consumption occurred during the chickpea diet and statistical adjustment for this reduced but did not eliminate the effect on serum lipids. There was no significant difference in glucose tolerance. Perceived general bowel health improved significantly during the chickpea diet although there was considerable individual variation. Some participants reported greater satiety during the chickpea diet. CONCLUSIONS: The small but significant decrease in serum TC and LDL-C during the chickpea diet compared to the equivalent fibre wheat diet was partly due to unintentional changes in macronutrient intake occurring because of chickpea ingestion. If dietary energy and macronutrients were not controlled, chickpea consumption might result in greater benefits via influence on these factors.     

Influence of substrate oxidation on the reward system, no role of dietary fibre

It has been suggested that a high intake of dietary fibre helps regulate energy intake and satiety. The present study aimed to examine whether dietary fibre influenced the liking and wanting components of the food reward system, the metabolic state or subsequent intake. Five sessions involving 32 normal-weight subjects (16 men and 16 women, 30.6 ± 7.6 year) were held. The sessions differed in the composition of the bread eaten during breakfasts (dietary fibre content varied from 2.4 to 12.8 g/100 g). Several factors such as the palatability, weight, volume, energy content and macronutrient composition of the breakfasts were adjusted. Energy expenditure, the respiratory quotient (R), olfactory liking for four foods, wanting for six other foods, and hunger sensations were evaluated before and after the breakfast, as well as before a morning snack. The results showed no significant differences after ingestion of the various breads. Interestingly, R correlated with olfactory liking and with wanting, which highlights in an original manner the influence of the metabolic state on hedonic sensations for food. In conclusion, dietary fibre was found to have no effect on olfactory liking and wanting, and had no detectable effect on satiety sensations or on subsequent energy intake.