Effects of physical and chemical characteristics of food on specific and general satiety

Impact of Agaricus bisporus mushroom consumption on satiety and food intake

Previous studies on mushrooms suggest that they can be more satiating than meat, but this effect has not been studied with protein-matched amounts. The objective of this study was to assess the differences with satiety and ten-day food intake between A. bisporus mushrooms (226 g) and meat (28 g) in a randomized open-label crossover study. Thirty-two healthy participants (17 women, 15 men) consumed two servings of mushrooms or meat for ten days. On the first day, fasted participants consumed protein-matched breakfasts. Participants rated their satiety using visual analogue scales (VAS) at baseline and at regular intervals after the meal. Three hours later, participants were served an ad libitum lunch. Participants were given mushrooms or meat to consume at home for the following nine days. Energy intake was assessed at the ad libitum lunch, and participants also completed diet diaries on the day of the study, day 2, and day 10. Participants reported less hunger (p = 0.045), greater fullness (p = 0.05), and decreased prospective consumption (p = 0.03) after the mushroom breakfast. There were no significant differences in participant ratings of satisfaction (p = 0.10). There were also no statistically significant differences in energy intake at the ad libitum lunch or with the diet diaries from days 1 (p = 0.61), 2 (p = 0.77), or 10 (p = 0.69). Mushroom consumption did increase fiber intake on days 1, 2, and 10 but the difference in fiber consumption was only statistically significant on day 2 (p = 0.0001). The mushroom intervention also did not affect energy intake over the ten day feeding period.

A brief review of salient factors influencing adult eating behaviour

A better understanding of the factors that influence eating behaviour is of importance as our food choices are associated with the risk of developing chronic diseases such as obesity, CVD, type 2 diabetes or some forms of cancer. In addition, accumulating evidence suggests that the industrial food production system is a major contributor to greenhouse gas emission and may be unsustainable. Therefore, our food choices may also contribute to climate change. By identifying the factors that influence eating behaviour new interventions may be developed, at the individual or population level, to modify eating behaviour and contribute to society’s health and environmental goals. Research indicates that eating behaviour is dictated by a complex interaction between physiology, environment, psychology, culture, socio-economics and genetics that is not fully understood. While a growing body of research has identified how several single factors influence eating behaviour, a better understanding of how these factors interact is required to facilitate the developing new models of eating behaviour. Due to the diversity of influences on eating behaviour this would probably necessitate a greater focus on multi-disciplinary research. In the present review, the influence of several salient physiological and environmental factors (largely related to food characteristics) on meal initiation, satiation (meal size) and satiety (inter-meal interval) are briefly discussed. Due to the large literature this review is not exhaustive but illustrates the complexity of eating behaviour. The present review will also highlight several limitations that apply to eating behaviour research.

Effects of fruit and vegetable, consumed in solid vs beverage forms, on acute and chronic appetitive responses in lean and obese adults

BACKGROUND

The effects of fruits and vegetables in solid vs beverage forms on human appetite and food intake, acutely and chronically, are unclear.

METHODS

This 21-week, randomized, crossover study assessed appetitive ratings following the inclusion of fruits and vegetables, in solid and beverage form, into the habitual diet of healthy lean (n=15) and overweight/obese (n=19) adults with low customary consumption. The primary acute outcomes were satiation (amount of challenge meal consumed), satiety (latency of subsequent eating event) and dietary compensation after a 400 kcal fruit preload. Ratings of appetite were also obtained before and after 8 weeks of required increased fruit and vegetable consumption (20% estimated energy requirement).

RESULTS

Acutely, overweight/obese participants reported smaller reductions of hunger after consuming the fruit preload in beverage compared with solid form (preload × form × body mass index effects, P=0.03). Participants also consumed significantly less of a challenge meal (in both gram and energy) after the ingestion of the solid fruit preload (P<0.005). However, the subsequent meal latency was not significantly different between the solid and the beverage fruit preloads. Total daily energy intake was significantly higher when the obese participants consumed the beverage fruit preload compared with the solid (P<0.001). Daily energy intake was markedly, but not significantly, higher among the lean with the beverage vs solid food form. Hunger and fullness ratings remained stable when participants consumed fruits and vegetables in solid or beverage form for 8 weeks each.

CONCLUSION

Acute post-ingestive appetitive responses were weaker following consumption of fruits in beverage vs solid food forms. Consumption of beverage or solid fruit and vegetable food loads for 8 weeks did not chronically alter appetitive responses.

Factors that determine energy compensation: a systematic review of preload studies

Insufficient energy compensation after a preload (meal, snack, or beverage) has been associated with excess energy intake, but experimental studies have used heterogeneous methodologies, making energy compensation difficult to predict. The aim of this systematic review was to analyze the relative contributions of two key variables, preload physical form and intermeal interval (IMI), to differences in energy compensation. Forty-eight publications were included, from which percent energy compensation (%EC) data were extracted for 253 interventions (121 liquid, 69 semisolid, 20 solid, and 43 composite preloads). Energy compensation ranged from −370% (overconsumption, mostly of liquids) to 450% (overcompensation). A meta-regression analysis of studies reporting positive energy compensation showed that IMI (as the predominant factor) together with preload physical form and energy contributed significantly to %EC differences, accounting for 50% of the variance, independently from gender and BMI. Energy compensation was maximized when the preload was in semisolid/solid form and the IMI was 30–120 min. These results may assist in the interpretation of studies assessing the relative efficacy of interventions to enhance satiety, including functional foods and weight management products.

Specific food structures supress appetite through reduced gastric emptying rate

The aim of this study was to determine the extent to which gastric layering and retention of a meal could be used to reduce appetite using the same caloric load. Liquid (control) and semi-solid (active) meals were produced with the same protein, fat, carbohydrate, and mass. These were fed to 10 volunteers on separate days in a crossover study, and subjective appetite ratings, gastric contents, and plasma cholecystokinin (CCK) were assessed over a period of 3 h. The active meal showed food boluses in the stomach persisting for ~45 min, slower emptying rates, and lower plasma CCK levels over the first hour. After the first hour, both gastric emptying rates and plasma CCK levels were similar for both systems and slightly increased compared with the unfed situation. Despite the lower plasma CCK levels for the active meal over the first hour, this meal reduced appetite more than the control meal over the 3 h of the study. For a moderately increased plasma CCK level in the fed state, appetite was correlated with the volume of gastric contents rather than gastric emptying rates or plasma CCK. This suggests that enhanced gastric retention was the key factor in decreasing appetite and was probably mediated by a combination of intestinal nutrient sensing and increased viscosity in the stomach.

Prebiotic potential and gastrointestinal effects of immature wheat grain (IWG) biscuits

In this study the effects of immature wheat grains (IWG), a natural source of fructo-oligosaccharides (FOS), on intestinal microbiota and gastrointestinal function were evaluated. Ileal effluents from three ileostomates were collected for 8 h after IWG-enriched or Control biscuit administration, and then fermented in vitro with human faecal inoculum. On fermentation broths, microbial counts and SCFA were measured. Moreover, we investigated the effect of IWG biscuits on gastric emptying. Twelve healthy volunteers underwent ultrasound measurement of gastric emptying of a standard meal consumed 5 h after a breakfast composed by lactose-free milk and IWG or Control biscuits; hunger and satiety sensations were also evaluated in this period. Bifidobacteria and lactic acid bacteria counts were higher (P < 0.05) in IWG than in Control cultures, supporting the prebiotic effects of IWG, probably linked to its FOS content; moreover IWG fermentation produced more acetate. In vivo IWG biscuits delayed gastric emptying of the next meal (P < 0.05), decreased hunger (P < 0.001) and increased satiety (P < 0.005). Therefore in vitro results substantiate the potential of IWG as a prebiotic ingredient and in vivo data suggest an effect of IWG on gastric emptying and on persistent satiety. These preliminary data tend to support the use of IWG in formulating functional prebiotic products suitable to promote satiety.

Satiating effect of a barley beta-glucan-enriched snack

OBJECTIVE

Increasing viscous dietary fiber in snacks may have several nutritional advantages, especially for adolescents. Having a snack that may exert direct health benefits and that may, at the same time, contribute to the voluntary reduction of energy intake through modulation of appetite may be a useful dietary strategy for energy control in adolescence. In this short-term study, a new type of biscuit containing 5.2% barley beta-glucan was produced and its effect on appetite moods and food intake was investigated.

METHODS

Twenty healthy adolescents were selected and randomly assigned to receive, as a midmorning snack, a 628 kJ (SP) or 1884 kJ (LP) preload of barley beta-glucan-enriched (BB) or control (CB) biscuits. Appetite ratings before and within 2 hours following the snack, as well as the energy intake at lunch, were recorded.

RESULTS

For all sensations, a peak at 15 minutes post-snack and a subsequent return to baseline value were shown. A decrease of the area under the curve (AUC) of the desire to eat and an increase of the AUC of fullness and satiety were recorded with SP-BB compared to SP-CB. The energy intake recorded at the lunch test was always significantly lower than that at the control lunch only in females (3048 kJ vs. 3890 kJ) independently from the type of snack consumed. Total energy intake significantly correlated with preload values both in females and in males, but not with the type of biscuit. Nutritional composition of meals consumed ad libitum did not vary significantly from those with different preloads.

CONCLUSIONS

The BB, consumed as a midmorning snack, although able to influence appetite ratings, did not modify food intake in a short time period.

beta-Glucan-enriched bread reduces energy intake and modifies plasma ghrelin and peptide YY concentrations in the short term

Dietary fibre consumption may help to control appetite and to reduce calorie intake. Underlying molecular mechanisms were not fully investigated. The aim of this study was to evaluate the effect of barley beta-glucans on short-term appetite and on satiety-related hormones in healthy subjects. Fourteen volunteers were selected and randomly assigned to have isocaloric breakfasts including a 3% beta-glucan-enriched bread (betaGB) or a control bread (CB). Post-breakfast individual self-records of appetite ratings and measure of calorie intake at an ad libitum lunch as well as measure of blood glucose, insulin, ghrelin and PYY concentrations, were performed. betaGB determined a significant higher reduction of hunger and increase of fullness and satiety than CB. Accordingly, a 19% reduction of energy intake at lunch subsequent to betaGB consumption compared to CB, was recorded. A 23% lower AUC(60-180) of plasma ghrelin and a 16% higher total AUC of PYY response after betaGB than CB consumption, independent from insulin response, was found. Glucose response was also blunted by betaGB vs CB. Barley beta-glucans were able to control appetite in the short term by modulating sensations and reducing energy intake. Data suggested for the first time that satiety effect of beta-glucans are mediated by ghrelin and PYY.

Eating slowly led to decreases in energy intake within meals in healthy women

Although reducing eating rate is frequently advocated for control of food intake and thus body weight, empirical evidence is extremely limited and inconsistent. We sought to compare the impact of slow and quick eating rates on development of satiation in healthy women. In a randomized design, 30 healthy women (22.9+/-7.1 years; body mass index [calculated as kg/m(2)] 22.1+/-2.9) were studied on two test visits to compare slow and quick eating rates. Satiation was examined as the main outcome, using the objective measure of energy intake during ad libitum meals. At designated times, subjects also rated perceived hunger, satiety, desire to eat, thirst and meal palatability on visual analogue scales. Slow rates of ingestion led to significant decreases in energy intake (quick: 645.7+/-155.9 kcal; slow: 579.0+/-154.7 kcal; P<0.05) and significant increases in water consumption (quick: 289.9+/-155.1 g; slow: 409.6+/-205.8 g; P<0.05). Despite higher energy intake upon meal completion under the quick condition, satiety was significantly lower than the slow condition (P<0.05). Accordingly, the quick condition showed a lower Satiating Efficiency Index (quick: 0.1; slow: 0.2; P<0.05). After meal completion, pleasantness ratings tended to be higher under the slow condition (P=0.04; but not significant after Bonferroni adjustment). Ad libitum energy intake was lower when the meal was eaten slowly, and satiety was higher at meal completion. Although more study is needed, these data suggest that eating slowly may help to maximize satiation and reduce energy intake within meals.

Higher satiety ratings following yogurt consumption relative to fruit drink or dairy fruit drink

OBJECTIVES

To compare the satiating power of semisolid and liquid yogurts with fruit beverages and dairy fruit drinks.

DESIGN AND PROCEDURES

Thirty-two volunteers (16 men and 16 women), ages 18 to 35 years, consumed a 200-kcal preload stimulus on four separate occasions. A tray lunch was presented 90 minutes after the preload and food consumption was measured.

METHODS

The stimuli were: a semisolid yogurt containing pieces of peach and eaten with a spoon (378 g), the same yogurt in a drinkable homogenized form (378 g), a peach-flavored dairy beverage (400 mL), and a peach juice beverage (400 mL). Participants rated hunger, thirst, satiety, and desire to eat at baseline and at 20-minute intervals after ingestion.

RESULTS

The two yogurts (semisolid and liquid) led to lower hunger and higher fullness ratings as compared with the fruit drink or dairy fruit drink. There was no difference in satiety profiles between the yogurt that was eaten with a spoon and the drinkable version. Energy intakes at lunch were the same across all four conditions (mean+/-standard deviation, 806+/-43 kcal).

CONCLUSIONS

The two yogurts were more satiating than the two beverages. However, lower hunger and higher fullness ratings after yogurt consumption did not lead to energy compensation at the next meal.

Dissociation of the effects of preload volume and energy content on subjective appetite and food intake

Previous research suggests that enhancing the volume of a food preload without altering energy content can result in reduced appetite, although the limited evidence means that the conditions under which this effect will occur are not yet clear. In the present study, we used a Universal Eating Monitor (UEM) to record test meal intake constantly, in parallel with appetite ratings, following soup-based preloads that varied both in volume (150 vs. 450 ml) and energy density (1.4 vs. 4.2 kJ/ml). Healthy young men (n=20) received four different preload conditions (repeated measures) followed by unlimited hot pasta test meals (interval 30 min). They completed appetite ratings during and after each laboratory session, and food diaries for the afternoon and evening following each session. Subjective appetite after the preloads was reduced by the high-volume preloads relative to low-volume preloads, with no difference between the two at each volume level. This indicates an effect of volume, but no effect of energy. Test meal intake in the high-volume, high-energy-density condition was reduced relative to the other conditions, which did not differ from one another. This indicates an effect of total energy, but no effect of volume. The dissociation between these different measures of appetite might be explained in terms of largely cognitive influences on subjective appetite between preload and test meal, contrasted with stronger physiological influences on actual intake during the test meal. With regard to previous studies, it is argued that food volume is more influential under circumstances where gastric volume is closer to its normal limits.

Beverage viscosity is inversely related to postprandial hunger in humans

Accumulating evidence indicates that energy-yielding beverages evoke weaker appetitive responses than more solid food items, but the properties responsible have not been characterized. The present study attempted to isolate an influence of viscosity. At weekly intervals, 84 adults ingested 325-ml (220 kcal) shakes that were matched on weight, volume, temperature, energy, macronutrient content, energy density, rate of consumption, cognitive expectations, palatability, appearance, and requirements for mechanical processing, but varied in viscosity. Twice appetitive ratings were obtained over the subsequent 4 h, while all intake was proscribed, and twice ratings were kept until the first spontaneous eating occasion comprised of > or =100 kcal. Dietary intake was recorded over the 24 h after shake ingestion. Significantly greater and more prolonged reductions of hunger were observed with the thicker shake. No significant differences were noted in the size or time to first meal or 24 h energy intake. These data indicate viscosity exerts an independent inverse effect on hunger in humans.

Dietary energy density and weight regulation

Dietary energy density (ED) has been suggested as an important determinant of energy intake and, therefore, energy regulation. This review summarizes published studies on the effects of dietary ED on hunger, satiety, energy intake, and body weight in healthy individuals, and compares the relative effects of ED manipulated by dietary fat only, fat and fiber, water, and type of sweetener. In short-term studies, consumption of low-ED foods promotes satiety, reduces hunger, and decreases energy intake with no marked differences between different dietary manipulations used to change ED. In addition, low-ED diets promote moderate weight loss in long-term studies. In studies lasting longer than 6 months, weight loss was more than three times as great in individuals consuming diets both low in fat and high in fiber compared with diets only low in fat (-3.4 kg versus -1.0 kg). Combined, these studies suggest that diets low in fat and high in fiber may be the most effective low-ED diets for promoting weight loss. Further research is needed on the effects of dietary ED by changing water or sweetener content.

The effects of a high-carbohydrate, high-protein or balanced lunch upon later food intake and hunger ratings

This study compared the satiating properties of three liquid lunches (450 kcal each), one dominant in protein (71.5% of energy), a second in carbohydrates (99% of energy) and a third containing an equal mixture of the first two formulations, in a within-subjects, repeated measures design. At an ad libitum dinner meal, 12 women consumed 31% more kilocalories in the high-carbohydrate lunch condition than in the high-protein lunch condition and 20% more kilocalories than in the mixture lunch condition. Similar results emerged for the amounts of protein and fat ingested at dinner. Subjects also reported significantly greater pre-dinner hunger and excitement about eating in the carbohydrate lunch condition than in the protein lunch condition. Greater enjoyment of dinner was also found after the carbohydrate lunch than after the mixture and protein lunches.

Physical state of meal affects gastric emptying, cholecystokinin release and satiety

To verify the influence of food consistency on satiety mechanisms we evaluated the effects of the same meal in solid-liquid (SM) and homogenized (HM) form on satiety sensation, gastric emptying rate and plasma cholecystokinin (CCK) concentration. Eight healthy men, aged 21-28 (mean 24.5) years were given two meals (cooked vegetables 250 g, cheese 35 g, croutons 50 g and olive oil 25 g, total energy 2573 kJ, with water 300 ml) differing only in physical state: SM and HM. The subjects consumed the meals in randomized order on non-consecutive days. The sensations of fullness, satiety and desire to eat were evaluated by means of a questionnaire, gastric emptying was assessed by ultrasonographic measurement of antral area, and plasma CCK concentration was measured by radioimmunoassay. The vegetable-rich meal was significantly more satiating (P < 0.05) when in the HM form than when eaten in a SM state. Furthermore, the overall gastric emptying time was significantly slowed (255 (SEM 11) min after HM v. 214 (SEM 12) min after SM; P < 0.05) and CCK peak occurred later (94 (SEM 12) min after HM v. 62 (SEM 11) min after SM; NS) when the food was consumed in the HM form. Independently of the type of meal, antral area was significantly related to fullness sensations (r2 0.46, P = 0.004). These results demonstrate that meal consistency is an important physical food characteristic which influences both gastric emptying rate and satiety sensation. Moreover, the relationship observed between antral area and fullness sensation confirms that antral distension plays a part in the regulation of eating behaviour.

A satiety quotient: a formulation to assess the satiating effect of food

This paper introduces a satiety quotient (SQ) to assess the satiating effect of an eating episode. This procedure constitutes an improvement on previous measures by considering the satiating effects of the eating episode over time. A satiety quotient was calculated from data obtained from several studies involving the presentation of a preload/meal to young lean male and female subjects. Subjects were presented with preloads/meals of varying composition, and motivation to eat immediately prior to, and periodically following, the eating episode were measured. Food and fluids were not consumed whilst motivation to eat was measured in the post preload/meal period. The SQ was calculated by dividing the difference between ratings of motivation to eat before and after the eating episode (pre minus post) by the weight or energy content of intake during the episode. This quotient relates intake to the rate of return of motivation to eat in the post-ingestive period, a relationship which is not apparent on separate examination of the amount consumed or ratings of motivation to eat. Development of this satiety quotient is a further contribution to the evolution of the concept of quantifying satiating effects of foods, and provides additional information on the effects of food attributes on short-term appetite control.