Measuring ‘expected satiety’ in a range of common foods using a method of constant stimuli

An afternoon snack of berries reduces subsequent energy intake compared to an isoenergetic confectionary snack

Observational studies suggest that increased fruit and vegetable consumption can contribute to weight maintenance and facilitate weight loss when substituted for other energy dense foods. Therefore, the purpose of the present study was to assess the effect of berries on acute appetite and energy intake. Twelve unrestrained pre-menopausal women (age 21 ± 2 y; BMI 26.6 ± 2.6 kg m(-2); body fat 23 ± 3%) completed a familiarisation trial and two randomised experimental trials. Subjects arrived in the evening (~5pm) and consumed an isoenergetic snack (65 kcal) of mixed berries (BERRY) or confectionary sweets (CONF). Sixty min later, subjects consumed a homogenous pasta test meal until voluntary satiation, and energy intake was quantified. Subjective appetite (hunger, fullness, desire to eat and prospective food consumption) was assessed throughout trials, and for 120 min after the test meal. Energy intake was less (P<0.001) after consumption of the BERRY snack (691 ± 146 kcal) than after the CONF snack (824 ± 172 kcal); whilst water consumption was similar (P=0.925). There were no trial (P>0.095) or interaction (P>0.351) effects for any subjective appetite ratings. Time taken to eat the BERRY snack (4.05 ± 1.12 min) was greater (P<0.001) than the CONF snack (0.93 ± 0.33 min). This study demonstrates that substituting an afternoon confectionary snack with mixed berries decreased subsequent energy intake at dinner, but did not affect subjective appetite. This dietary strategy could represent a simple method for reducing daily energy intake and aiding weight management.

Energy-dense snacks can have the same expected satiation as sugar-containing beverages

Sugar-sweetened beverages (SSBs) are thought to be problematic for weight management because energy delivered in liquid form may be less effective at suppressing appetite than solid foods. However, little is known about the relative 'expected satiation' (anticipated fullness) of SSBs and solid foods. This is relevant because expected satiation is an important determinant of portion selection and energy intake. Here, we used a method of constant stimuli to assess the expected satiation of test meals that were presented in combination with different caloric and non-caloric beverages (500 ml) (Experiment 1 and 2), as well as with high-energy solid snack foods (Experiment 2). All energy-containing beverages and snack foods were presented in 210 kcal portions. Both experiments found that expected satiation was greater for meals containing caloric versus non-caloric beverages (201.3 ± 17.3 vs. 185.4 ± 14.1 kcal in Experiment 2; p < 0.05). Further, Experiment 2 showed that this difference was greater in participants who were familiar with our test beverages, indicating a role for learning. Notably, we failed to observe a significant difference in expected satiation between any of the caloric beverages and snack foods in Experiment 2 (range: 192.5-205.2 kcal; p = 0.87). This finding suggests that it may be more appropriate to consider beverages and solid foods on the same continuum, recognizing that the expected satiation of some solid foods is as weak as some beverages.

Are You Sure? Confidence about the Satiating Capacity of a Food Affects Subsequent Food Intake

Expectations about a food’s satiating capacity predict self-selected portion size, food intake and food choice. However, two individuals might have a similar expectation, but one might be extremely confident while the other might be guessing. It is unclear whether confidence about an expectation affects adjustments in energy intake at a subsequent meal. In a randomized cross-over design, 24 subjects participated in three separate breakfast sessions, and were served a low-energy-dense preload (53 kcal/100 g), a high-energy-dense preload (94 kcal/100 g), or no preload. Subjects received ambiguous information about the preload’s satiating capacity and rated how confident they were about their expected satiation before consuming the preload in its entirety. They were served an ad libitum test meal 30 min later. Confidence ratings were negatively associated with energy compensation after consuming the high-energy-dense preload (r = −0.61; p = 0.001). The same relationship was evident after consuming the low-energy-dense preload, but only after controlling for dietary restraint, hunger prior to, and liking of the test meal (p = 0.03). Our results suggest that confidence modifies short-term controls of food intake by affecting energy compensation. These results merit consideration because imprecise caloric compensation has been identified as a potential risk factor for a positive energy balance and weight gain.

Effect of training on the reliability of satiety evaluation and use of trained panellists to determine the satiety effect of dietary fibre: a randomised controlled trial

Background

The assessment of satiety effects on foods is commonly performed by untrained volunteers marking their perceived hunger or fullness on line scales, marked with pre-set descriptors. The lack of reproducibility of satiety measurement using this approach however results in the tool being unable to distinguish between foods that have small, but possibly important, differences in their satiety effects. An alternate approach is used in sensory evaluation; panellists can be trained in the correct use of the assessment line-scale and brought to consensus on the meanings of descriptors used for food quality attributes to improve the panel reliability. The effect of training on the reliability of a satiety panel has not previously been reported.

Method

In a randomised controlled parallel intervention, the effect of training in the correct use of a satiety labelled magnitude scale (LMS) was assessed versus no-training. The test-retest precision and reliability of two hour postprandial satiety evaluation after consumption of a standard breakfast was compared. The trained panel then compared the satiety effect of two breakfast meals containing either a viscous or a non-viscous dietary fibre in a crossover trial.

Results

A subgroup of the 23 panellists (n = 5) improved their test re-test precision after training. Panel satiety area under the curve, “after the training” intervention was significantly different to “before training” (p < 0.001). Reliability of the panel determined by intraclass correlation (ICC) of test and retest showed improved strength of the correlation from 0.70 pre-intervention to 0.95 post intervention. The trained “satiety expert panel” determined that a standard breakfast with 5g of viscous fibre gave significantly higher satiety than with 5g non-viscous fibre (area under curve (AUC) of 478.2, 334.4 respectively) (p ≤ 0.002).

Conclusion

Training reduced between panellist variability. The improved strength of test-retest ICC as a result of the training intervention suggests that training satiety panellists can improve the discriminating power of satiety evaluation.

So Many Brands and Varieties to Choose from: Does This Compromise the Control of Food Intake in Humans?

The recent rise in obesity is widely attributed to changes in the dietary environment (e.g., increased availability of energy-dense foods and larger portion sizes). However, a critical feature of our "obesogenic environment" may have been overlooked - the dramatic increase in "dietary variability" (the tendency for specific mass-produced foods to be available in numerous varieties that differ in energy content). In this study we tested the hypothesis that dietary variability compromises the control of food intake in humans. Specifically, we examined the effects of dietary variability in pepperoni pizza on two key outcome variables; i) compensation for calories in pepperoni pizza and ii) expectations about the satiating properties of pepperoni pizza (expected satiation). We reasoned that dietary variability might generate uncertainty about the postingestive effects of a food. An internet-based questionnaire was completed by 199 adults. This revealed substantial variation in exposure to different varieties of pepperoni pizza. In a follow-up study (n= 66; 65% female), high pizza variability was associated with i) poorer compensation for calories in pepperoni pizza and ii) lower expected satiation for pepperoni pizza. Furthermore, the effect of uncertainty on caloric compensation was moderated by individual differences in decision making (loss aversion). For the first time, these findings highlight a process by which dietary variability may compromise food-intake control in humans. This is important because it exposes a new feature of Western diets (processed foods in particular) that might contribute to overeating and obesity.

Mind over platter: pre-meal planning and the control of meal size in humans

It is widely accepted that meal size is governed by psychological and physiological processes that generate fullness towards the end of a meal. However, observations of natural eating behaviour suggest that this preoccupation with within-meal events may be misplaced and that the role of immediate post-ingestive feedback (for example, gastric stretch) has been overstated. This review considers the proposition that the locus of control is more likely to be expressed in decisions about portion size, before a meal begins. Consistent with this idea, we have discovered that people are extremely adept at estimating the ‘expected satiety' and ‘expected satiation' of different foods. These expectations are learned over time and they are highly correlated with the number of calories that end up on our plate. Indeed, across a range of foods, the large variation in expected satiety/satiation may be a more important determinant of meal size than relatively subtle differences in palatability. Building on related advances, it would also appear that memory for portion size has an important role in generating satiety after a meal has been consumed. Together, these findings expose the importance of planning and episodic memory in the control of appetite and food intake in humans.

Expected Satiety: Application to Weight Management and Understanding Energy Selection in Humans

Recent advances in the approaches used to quantify expectations of satiation and satiety have led to a better understanding of how humans select and consume food, and the associated links to energy intake regulation. When compared calorie for calorie some foods are expected to deliver several times more satiety than others, and multiple studies have demonstrated that people are able to discriminate between similar foods reliably and with considerable sensitivity. These findings have implications for the control of meal size and the design of foods that can be used to lower the energy density of diets. These methods and findings are discussed in terms of their implications for weight management. The current paper also highlights why expected satiety may also play an important role beyond energy selection, in moderating appetite sensations after a meal has been consumed, through memory for recent eating and the selection of foods across future meals.

Effects of meal variety on expected satiation: evidence for a 'perceived volume' heuristic

Meal variety has been shown to increase energy intake in humans by an average of 29%. Historically, research exploring the mechanism underlying this effect has focused on physiological and psychological processes that terminate a meal (e.g., sensory-specific satiety). We sought to explore whether meal variety stimulates intake by influencing pre-meal planning. We know that individuals use prior experience with a food to estimate the extent to which it will deliver fullness. These 'expected satiation' judgments may be straightforward when only one meal component needs to be considered, but it remains unclear how prospective satiation is estimated when a meal comprises multiple items. We hypothesised that people simplify the task by using a heuristic, or 'cognitive shortcut.' Specifically, as within-meal variety increases, expected satiation tends to be based on the perceived volume of food(s) rather than on prior experience. In each trial, participants (N = 68) were shown a plate of food with six buffet food items. Across trials the number of different foods varied in the range one to six. In separate tasks, the participants provided an estimate of their combined expected satiation and volume. When meal variety was high, judgments of perceived volume and expected satiation 'converged.' This is consistent with a common underlying response strategy. By contrast, the low variety meals produced dissociable responses, suggesting that judgments of expected satiation were not governed solely by perceived volume. This evidence for a 'volume heuristic' was especially clear in people who were less familiar with the meal items. Together, these results are important because they expose a novel process by which meal variety might increase food intake in humans.

High satiety expectations of a first course promote selection of less energy in a main course picture task

One of the factors determining meal size is the expectation one has about satiating properties of foods. Foods eliciting low satiety expectations are often chosen in larger portions. We investigated whether satiety expectations of one food lead to a different portion size selection of other foods, using an online picture task. One hundred and twenty-six subjects (64 unrestrained, 62 restrained) participated in three conditions (within-subject). In two conditions subjects were asked to imagine they consumed soup as a first course. They were shown pictures of soups differing in terms of visual attributes, e.g. colour intensity, ingredients variety, etc. that conveyed a high or low expected satiety. In the control condition, no picture was shown. After viewing either a soup picture or no picture, subjects chose an ideal menu and portion size out of several other foods (meat, side dishes and vegetables) via an online choice task, specifically developed for this experiment. The energy (kcal) and weight (grams) selected for the main course was measured. More energy was chosen in the low satiety compared with the high satiety soup picture condition, but this effect was only significant for restrained eaters. This study shows that satiety expectations of a first course 'carry over' to the rest of the menu in people who carefully watch their diet, i.e. restrained eaters make satiety estimations for an entire menu. Our online choice task was able to capture these estimations in an implicit manner.

Mechanisms of the portion size effect. What is known and where do we go from here?

Childhood obesity is a persistent problem worldwide, and of particular concern in the United States. Clarifying the role of the food environment in promoting overeating is an important step toward reducing the prevalence of obesity. One potential contributor to the obesity epidemic is the increased portion sizes of foods commonly served. Portion sizes of foods served both at home and away from home have dramatically increased over the past 40 years. Consistently, short-term studies have demonstrated that increasing portion size leads to increased food intake in adults and children, a phenomenon known as the portion size effect. However, the mechanisms underlying this effect are poorly understood. Understanding these mechanisms could assist in clarifying the relationship between portion size and weight status and help inform the development of effective obesity interventions. First, we review the role of visual cues, such as plate size, unit, and utensil size as a potential moderator of the portion size effect. In addition, we discuss meal microstructure components including bite size, rate, and frequency, as these may be altered in response to different portion sizes. We also review theories that implicate post-ingestive, flavor-nutrient learning as a key moderator of the portion size effect. Furthermore, we present preliminary data from an ongoing study that is applying neuroimaging to better understand these mechanisms and identify modifiable child characteristics that could be targeted in obesity interventions. Our tentative findings suggest that individual differences in cognitive (e.g. loss of control eating) and neural responses to food cues may be critical in understanding the mechanisms of the portion size effect. To advance this research area, studies that integrate measures of individual subject-level differences with assessment of food-related characteristics are needed.

Oleic acid content of a meal promotes oleoylethanolamide response and reduces subsequent energy intake in humans

Animal data suggest that dietary fat composition may influence endocannabinoid (EC) response and dietary behavior. This study tested the hypothesis that fatty acid composition of a meal can influence the short-term response of ECs and subsequent energy intake in humans. Fifteen volunteers on three occasions were randomly offered a meal containing 30 g of bread and 30 mL of one of three selected oils: sunflower oil (SO), high oleic sunflower oil (HOSO) and virgin olive oil (VOO). Plasma EC concentrations and appetite ratings over 2 h and energy intake over 24 h following the experimental meal were measured. Results showed that after HOSO and VOO consumption the circulating oleoylethanolamide (OEA) was significantly higher than after SO consumption; a concomitantly significant reduction of energy intake was found. For the first time the oleic acid content of a meal was demonstrated to increase the post-prandial response of circulating OEA and to reduce energy intake at subsequent meals in humans.

Effects of repeated consumption on sensory-enhanced satiety

Previous research has suggested that sensory characteristics of a drink modify the acute satiating effects of its nutrients, with enhanced satiety being evident when a high-energy drink was thicker and tasted creamier. The present study tested whether this modulation of satiety by sensory context was altered by repeated consumption. Participants (n 48) consumed one of four drinks mid-morning on seven non-consecutive days, with satiety responses being measured pre-exposure (day 1), post-exposure (day 6) and at a 1-month follow-up. The drinks combined two levels of energy (lower energy (LE), 326 kJ and higher energy, 1163 kJ) with two levels of satiety-predictive sensory characteristics (low sensory (LS) or enhanced sensory). Test lunch intake 90 min after drink consumption depended on both the energy content and sensory characteristics of the drink before exposure, but on the energy content alone after exposure and at the follow-up. The largest change was an increase in test meal intake over time in the LE/LS condition. The effects on intake were reflected in appetite ratings, with rated hunger and expected filling affected by sensory characteristics and energy content pre-exposure, but were largely determined by energy content post-exposure and at the follow-up. In contrast, a measure of expected satiety reflected sensory characteristics regardless of energy content on all the three test days. Overall, these data suggest that some aspects of the sensory modulation of satiety are changed by repeated consumption, with covert energy becoming more effective in suppressing appetite over time, but also suggest that these behavioural changes are not readily translated into expectations of satiety.

Acute sleep deprivation increases portion size and affects food choice in young men

Acute sleep loss increases food intake in adults. However, little is known about the influence of acute sleep loss on portion size choice, and whether this depends on both hunger state and the type of food (snack or meal item) offered to an individual. The aim of the current study was to compare portion size choice after a night of sleep and a period of nocturnal wakefulness (a condition experienced by night-shift workers, e.g. physicians and nurses). Sixteen men (age: 23 ± 0.9 years, BMI: 23.6 ± 0.6 kg/m(2)) participated in a randomized within-subject design with two conditions, 8-h of sleep and total sleep deprivation (TSD). In the morning following sleep interventions, portion size, comprising meal and snack items, was measured using a computer-based task, in both fasted and sated state. In addition, hunger as well as plasma levels of ghrelin were measured. In the morning after TSD, subjects had increased plasma ghrelin levels (13%, p=0.04), and chose larger portions (14%, p=0.02), irrespective of the type of food, as compared to the sleep condition. Self-reported hunger was also enhanced (p<0.01). Following breakfast, sleep-deprived subjects chose larger portions of snacks (16%, p=0.02), whereas the selection of meal items did not differ between the sleep interventions (6%, p=0.13). Our results suggest that overeating in the morning after sleep loss is driven by both homeostatic and hedonic factors. Further, they show that portion size choice after sleep loss depend on both an individual's hunger status, and the type of food offered.

Estimating food portions. Influence of unit number, meal type and energy density

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University staff/students showed poor awareness of appropriate portion sizes.

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Unit number and meal classification affected portion size estimation.

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Portion sizes in sugary drinks, pizza and pasta were underestimated by 30–46%.

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Women were better at estimating food portion sizes than men.

Estimating how much is appropriate to consume can be difficult, especially for foods presented in multiple units, those with ambiguous energy content and for snacks. This study tested the hypothesis that the number of units (single vs. multi-unit), meal type and food energy density disrupts accurate estimates of portion size. Thirty-two healthy weight men and women attended the laboratory on 3 separate occasions to assess the number of portions contained in 33 foods or beverages of varying energy density (1.7–26.8 kJ/g). Items included 12 multi-unit and 21 single unit foods; 13 were labelled “meal”, 4 “drink” and 16 “snack”. Departures in portion estimates from reference amounts were analysed with negative binomial regression. Overall participants tended to underestimate the number of portions displayed. Males showed greater errors in estimation than females (p = 0.01). Single unit foods and those labelled as ‘meal’ or ‘beverage’ were estimated with greater error than multi-unit and ‘snack’ foods (p = 0.02 and p < 0.001 respectively). The number of portions of high energy density foods was overestimated while the number of portions of beverages and medium energy density foods were underestimated by 30–46%. In conclusion, participants tended to underestimate the reference portion size for a range of food and beverages, especially single unit foods and foods of low energy density and, unexpectedly, overestimated the reference portion of high energy density items. There is a need for better consumer education of appropriate portion sizes to aid adherence to a healthy diet.

Plate size does not affect perception of food portion size

BACKGROUND

Evidences have suggested that larger utensils may provoke 'size-contrast illusions', influencing the perceived volume and food consumption.

OBJECTIVE

To analyse the influence of plate size on the visual estimate of food portion size.

METHODS

Two 400 g portions of pasta with tomato sauce were presented on two plates of different diameters (24.0 and 9.0 cm). Each participant visually estimated on an individual basis the quantities of the pasta portions (g) present on each plate. In addition, each subject classified the size of the portions on each plate as 'small', 'medium' and 'large'. The mean estimates of the amount of pasta on each plate were compared by the nonparametric Mann-Whitney. The differences in the frequencies of portion classifications between plates were evaluated by the chi-squared test.

RESULTS

Forty-eight students (average 25.8 ± 8.9 years) participated in the study. There was no difference in the median amount of pasta estimated for the large and small plates (150 g; range 50-500 and 115 g; range 40-500 g, respectively). The classification of the portion size as 'large' was reported by a significantly greater number of persons when they evaluated the amount of pasta arranged on the large plate compared to the small plate (47.9 versus 22.9%, respectively; P = 0.018).

CONCLUSION

The size of the plate did not influence the estimate of food portions, even though it did influence the classification of portion size.

Increased familiarity with eating a food to fullness underlies increased expected satiety

Expected satiety informs self-selected portion sizes and thereby influences energy intake. At present the extent to which these beliefs are learned remains unclear. In an initial study the proposition that familiarity influences expected satiety was explored. Self-report measures of familiarity, along with other measures such as degree of liking, were collected for wine gums and milk chocolate, together with expected satiety estimates obtained using a psychophysical task. Familiarity was indeed significantly correlated with expected satiety, but only in respect of frequency of having eaten the food to fullness. In a second experiment a significant increase in expected satiety was observed after eating a large portion of wine gums at a subsequent test session. Together, these findings indicate that expected satiety changes in response to increased familiarity of eating a food to satiety.

Serving size guidance for consumers: is it effective?

Larger portion sizes (PS) may be inciting over-eating and contributing to obesity rates. Currently, there is a paucity of data on the effectiveness of serving size (SS) guidance. The aims of the present review are to evaluate SS guidance; the understanding, usability and acceptability of such guidance, its impact on consumers and potential barriers to its uptake. A sample of worldwide SS guidance schemes (n 87) were identified using targeted and untargeted searches, overall these were found to communicate various inconsistent and often conflicting messages about PS selection. The available data suggest that consumers have difficulty in understanding terms such as 'portion size' and 'serving size', as these tend to be used interchangeably. In addition, discrepancies between recommended SS and those present on food labels add to the confusion. Consumers generally understand and visualise SS best when expressed in terms of household measures rather than actual weights. Only a limited number of studies have examined the direct impact of SS guidance on consumer behaviour with equivocal results. Although consumers recognise that guidance on selecting SS would be helpful, they are often unwilling to act on such guidance. The challenge of achieving consumer adherence to SS guidance is formidable due to several barriers including chronic exposure to larger PS, distorted consumption norms and perceptions, the habit of 'cleaning one's plate' and language barriers for ethnic minorities. In conclusion, the impact of SS guidance on consumers merits further investigation to ensure that future guidance resonates with consumers by being more understandable, usable and acceptable.

Mapping the tip of the tongue--deprivation, sensory sensitisation, and oral haptics

We investigated the impact of food deprivation on oral and manual haptic size perception of food and non-food objects. From relevant theories (need-proportional perception, motivated perception, frustrative nonreward, perceptual defence, and sensory sensitisation) at least four completely different competing predictions can be derived. Testing these predictions, we found across four experiments that participants estimated the length of both non-food and food objects to be larger when hungry than when satiated, which was true only for oral haptic perception, while manual haptic perception was not influenced by hunger state. Subjectively reported hunger correlated positively with estimated object size in oral, but not in manual, haptic perception. The impact of food deprivation on oral perception vanished after oral stimulations even for hungry individuals. These results favour a sensory sensitisation account maintaining that hunger itself does not alter oral perception but the accompanying lack of sensory stimulation of the oral mucosa. Both oral and manual haptic perception tended to underestimate actual object size. Finally, an enhancing effect of domain-target matching was found, ie food objects were perceived larger by oral than by manual haptics, while non-food objects were perceived larger by manual than by oral haptics.

Texture and satiation: the role of oro-sensory exposure time

One of the characteristics of the current obesogenic food supply is the large availability of foods that can be ingested quickly. Controlled nutrition intervention studies have shown that the ingestion of simple energy containing beverages, which are consumed very quickly, do not lead to a lower compensatory intake of other foods. One of the theories behind this observation is that calories that are ingested quickly are not well sensed by the sense of taste, and do not lead to an adequate satiety response. This idea is confirmed by the results of a series of studies, where we have shown that the low satiation/satiety response of beverages can be largely attributed to their short oral residence time. Prolonging the oro-sensory exposure time to foods leads to earlier meal termination and/or a higher satiety response. The low satiation/satiety response to simple energy containing beverages is congruent with the observation from studies on the cephalic phase response to foods, i.e. the physiological response to sensory signals. Energy containing beverages do not lead to an adequate cephalic phase response. Various recent studies showed that slower eating leads to higher levels of satiety hormones. These results are in line with the idea that the sense of taste is a nutrient sensor which informs the brain and the gut about the inflow of nutrients. The sense of taste has an important contribution to the satiating effect of foods. One of the challenges in future research is to see whether or not these proofs of principles can be applied in longer term studies with regular commercial foods. This may make our obesogenic food supply more satiating, and may lead to a lower energy intake.

The weight of the container influences expected satiety, perceived density, and subsequent expected fullness

We report a study designed to investigate the influence of the weight of the container on expected satiety prior to tasting the food within and on the perceived density of the food and any feelings of fullness expected to follow consumption (expected satiation). The results demonstrate that the contents of a heavier container are expected to be more satiating than when exactly the same contents are presented in a visually-identical, but physically lighter, container (even before the food has been tasted). In addition, we were able to validate a "weight-density" illusion, since the weight of the container was shown to influence the perceived density of the sample. Put simply, the heavier the container, the denser the food sample was perceived to be.

Successful development of satiety enhancing food products: towards a multidisciplinary agenda of research challenges

In the context of increasing prevalence of overweight and obesity in societies worldwide, enhancing the satiating capacity of foods may help people control their energy intake and weight. This requires an integrated approach between various food-related disciplines. By structuring this approach around the new product development process, this paper aims to present the contours of such an integrative approach by going through the current state of the art around satiety enhancing foods. It portrays actual food choice as the end result of a complex interaction between internal satiety signals, other food benefits, and environmental cues. Three interrelated routes to satiating enhancement are to change the food composition to develop stronger physiological satiation and satiety signals, anticipate and build on smart external stimuli at the moment of purchase and consumption, and improve palatability and acceptance of satiety enhanced foods. Key research challenges in achieving these routes in the field of nutrition, food technology, consumer, marketing, and communication are outlined.

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.

Satiety-relevant sensory qualities enhance the satiating effects of mixed carbohydrate-protein preloads

BACKGROUND

Orosensory cues such as food texture and flavor have been shown to play a role in satiation, but their role in satiety remains less clear.

OBJECTIVE

The objective was to determine whether satiety-relevant orosensory cues enhance the satiating effects of energy in the context of beverage preloads.

DESIGN

The effects of 6 drink preloads that combined 2 amounts of energy [high energy (HE): 279 kcal; low energy (LE): 78 kcal] and 3 satiety-relevant sensory contexts [low sensory (LS), medium sensory (MS), and high sensory (HS)] on subsequent appetite and test meal intake were assessed in 36 healthy nonobese volunteers.

RESULTS

The ability of the preloads to modify appetite 30 min after consumption depended on both energy content and sensory context (P-interaction < 0.05), with hunger significantly being lower after consumption of the HE than after the LE preload in the HS context (P < 0.001), tending to be lower in the MS context (P = 0.08), but not different in the LS context. Food intake at lunch was lower after the HE than after the LE preloads (effect of energy P < 0.001), but this effect depended on sensory context (P < 0.005). The degree to which reduced test meal intake compensated for the added energy in the HE preloads was 88% in the HS context, which was significantly greater than in the MS (47%) and LS (18%) contexts.

CONCLUSION

Small changes in the sensory characteristics of drinks altered the degree to which added energy was satiating, which implies that nutrients become more satiating when they are predicted by relevant sensory cues such as thickness and creaminess. This trial was registered at http://www.controlled-trials.com as ISRCTN36258511.

Children's familiarity with snack foods changes expectations about fullness

BACKGROUND

Palatability is regarded as a major determinant of children's energy intake. However, few studies have considered nonhedonic beliefs about foods. In adults, there is emerging evidence that expectations about the satiating properties of foods are an important determinant of meal size, and these beliefs are learned.

OBJECTIVE

We measured and quantified children's expected satiation across energy-dense snack foods by using a method of adjustment. Participants changed a comparison-food portion (pasta and tomato sauce) to match the satiation that they expected from a snack food. We predicted that children who were especially familiar with snack foods would expect the foods to generate greater satiation and that children who were unfamiliar with snack foods would match expected satiation on the basis of the physical characteristics (perceived volume) of the foods.

DESIGN

Seventy 11- to 12-y-old children completed measures of expected satiation, perceived volume, familiarity, and liking across 6 snack foods.

RESULTS

As anticipated, familiarity and expected satiation were positively related (r = 0.37, P = 0.002), and this association remained after liking was controlled for. Furthermore, expected-satiation and perceived-volume judgments were more dissimilar as familiarity with the foods increased.

CONCLUSIONS

Our findings highlight the role of learning in shaping children's beliefs about the postingestive effects of the consumption of foods; children who ate the foods more often expected them to deliver greater satiation. Furthermore, our findings suggest that, in the absence of prior experience, children rely on a food's physical characteristics (a less-complex strategy) when they judge expected satiation. This trial was registered at clinicaltrials.gov as NCT01403753.

Expected satiation after repeated consumption of low- or high-energy-dense soup

We investigated whether repeated consumption of a low-energy-dense (LED; 208 kJ/100 g) or high-energy-dense (HED; 645 kJ/100 g) soup modifies expectations relating to the satiating capacity of the food, and its subsequent intake. In study 1, participants consumed either a novel-flavoured LED (n 32; 21 (SD 1·6) years, BMI 21·4 (SD 1·6) kg/m(2)) or HED soup (n 32; 21 (SD 1·6) years, BMI 21·3 (SD 1·7) kg/m(2)). Soup was served in a fixed amount on days 1-4 and ad libitum on day 5. 'Expected satiation' was measured on days 1, 2 and 5. Expected satiation did not change after repeated consumption of the LED or HED soup. Ad libitum intake did not differ between the LED (461 (SD 213) g) and HED soup (391 (SD 164) g). Only on day 1, expected satiation was higher for the HED soup than for the LED soup (P = 0·03), suggesting a role for sensory attributes in expected satiation. In study 2, thirty participants (21 (SD 1·6) years, BMI 21·3 (SD 1·7) kg/m(2)) performed a single measurement of expected satiation of the LED and HED soup, and four commercially available types of soup. Ratings on sensory attributes were associated with expected satiation. Results on expected satiation coincided with those of study 1. Thickness and intensity of taste were independently associated with expected satiation. Expectations may initially rely on sensory attributes and previous experiences, and are not easily changed.

The effect of within-meal protein content and taste on subsequent food choice and satiety

It is posed that protein intake is tightly regulated by the human body. The role of sensory qualities in the satiating effects of protein, however, requires further clarification. Our objective was to determine the effect of within-meal protein content and taste on subsequent food choice and satiety. We used a cross-over design whereby sixty healthy, unrestrained subjects (twenty-three males and thirty-seven females) with a mean age of 20·8 (sd 2·1) years and a mean BMI of 21·5 (sd 1·6) kg/m2 were offered one of four isoenergetic preloads (rice meal) for lunch: two low in protein (about 7 % energy derived from protein) and two high in protein (about 25 % energy from protein). Both had a sweet and savoury version. At 30 min after preload consumption, subjects were offered an ad libitum buffet, consisting of food products differing in protein content (low/high) and taste (sweet/savoury). In addition, the computerised Leeds Food Preference Questionnaire (LFPQ) was run to assess several components of food reward. The results showed no effect of protein content of the preloads on subsequent food choice. There was an effect of taste; after eating the savoury preloads, choice and intake of sweet products were higher than of savoury products. No such preference was seen after the sweet preloads. No differences in satiety were observed. To conclude, within one eating episode, within-meal protein content in these quantities seems not to have an effect on subsequent food choice. This appears to be mostly determined by taste, whereby savoury taste exerts the strongest modulating effect. The results of the LFPQ provided insight into underlying processes.

Estimated portion sizes of snacks and beverages differ from reference amounts and are affected by appetite status in non-obese men

Objective

To explore the extent to which appetite status influences portion size estimation in men under laboratory conditions and to quantify how much participants’ portion estimates differed from the recommended portion sizes defined by authoritative bodies (i.e. government and health professionals’ reference amounts).

Design

Repeated, randomized cross-over trial with each participant attending the laboratory on four separate occasions. At each session, participants rated the number of portions of eight foods and beverages displayed in front of them. Participants rated portions twice after consuming breakfast (full conditions) and twice after an overnight fast (hungry conditions). Portion estimates were compared with reference amounts from the British and American Dietetic Associations, from the UK Food Standards Agency and from the US Food and Drug Administration.

Setting

Food skills laboratory, University of Chester, UK.

Subjects

Twenty-seven non-obese men (mean age 24·9 (sd 6·5) years).

Results

Portion size estimates for all items were significantly smaller under hungry than under full conditions (P < 0·01). Relative to reference instruments, estimates were significantly smaller for all foods except banana, irrespective of appetite status (P < 0·001).

Conclusions

In this data set, appetite status altered the perception of food amounts. There were large discrepancies between participants’ perception of a portion and recommendations from health professionals and government standards. Nutritional educational strategies should take into account the role of hunger along with a person's familiarity with existing portion size systems when advising on portion sizes.

Why liquid energy results in overconsumption

Liquids have been shown to have a low satiating efficiency. The may be related to the high rate of consumption for liquids which may be higher than 200 g/min. In a number of studies, we showed that the positive relationship between eating rate and energy intake is mediated by oro-sensory exposure time. Longer sensory exposure times are consistently associated with lower food intakes. This observation maybe linked to the role of cephalic phase responses to foods. Cephalic phase responses are a set of physiological responses, which are conceived to prepare the digestive system for the incoming flow of nutrients after ingestion, with the aim of maintaining homeostasis. Results from various studies suggest that cephalic phase responses are much smaller (absent) for liquids compared to solids. It is hypothesised that the absence of cephalic phase responses to liquid foods may be one of the causes why liquid energies enter the body undetected and lead to weak energy intake compensation. This idea fits with the concept of the taste system as a nutrient-sensing system that informs the brain and the gastro-intestinal system about what is coming into our body. With liquids, this system is bypassed. Slower eating may help the human body to associate the sensory signals from food with their metabolic consequences. Foods that are eaten quickly may impair this association, and may therefore lead to overconsumption of energy, and ultimately to weight gain.

The control of meal size in human subjects: a role for expected satiety, expected satiation and premeal planning

Unlike energy expenditure, energy intake occurs during discrete events: snacks and meals. The prevailing view is that meal size is governed by physiological and psychological events that promote satiation towards the end of a meal. This review explores an alternative and perhaps controversial proposition. Specifically that satiation plays a secondary role, and that meal size (kJ) is controlled by decisions about portion size, before a meal begins. Recently, techniques have been developed that enable us to quantify ‘expected satiation’ and ‘expected satiety’ (respectively, the fullness and the respite from hunger that foods are expected to confer). When compared on a kJ-for-kJ basis, these expectations differ markedly across foods. Moreover, in self-selected meals, these measures are remarkably good predictors of the energy content of food that ends up on our plate, even more important than palatability. Expected satiation and expected satiety are influenced by the physical characteristics of a food (e.g. perceived volume). However, they are also learned. Indeed, there is now mounting evidence for ‘expected-satiation drift’, a general tendency for a food to have higher expected satiation as it increases in familiarity. Together, these findings show that important elements of control (discrimination and learning/adaptation) are clearly evident in plans around portion size. Since most meals are eaten in their entirety, understanding the nature of these controls should be given high priority.

'Expected satiety' changes hunger and fullness in the inter-meal interval

Previously, we have shown that foods differ markedly in the satiety that they are expected to confer (compared calorie-for-calorie). In the present study we tested the hypothesis that 'expected satiety' plays a causal role in the satiety that is experienced after a food has been consumed. Before lunch, participants (N=32) were shown the ingredients of a fruit smoothie. Half were shown a small portion of fruit and half were shown a large portion. Participants then assessed the expected satiety of the smoothie and provided appetite ratings, before, and for three hours after its consumption. As anticipated, expected satiety was significantly higher in the 'large portion' condition. Moreover, and consistent with our hypothesis, participants reported significantly less hunger and significantly greater fullness in the large-portion condition. Importantly, this effect endured throughout the test period (for three hours). Together, these findings confirm previous reports indicating that beliefs and expectations can have marked effects on satiety and they show that this effect can persist well into the inter-meal interval. Potential explanations are discussed, including the prospect that satiety is moderated by memories of expected satiety that are encoded around the time that a meal is consumed.

Effects of repeated exposure on liking for a reduced-energy-dense food

BACKGROUND

Reduced-energy-dense diet foods are often formulated to match the sensory characteristics of their regular-energy-dense counterparts. However, the extent to which attitudes toward a reduced-energy-dense food remain constant, even after repeated ingestion, remains to be explored systematically.

OBJECTIVE

The objective was to determine whether liking, "expected satiety," and "expected satiation" change after repeated exposure to a familiar food that has been reduced in energy density. Expected satiety and expected satiation refer to the extent to which foods are expected to stave off hunger and to deliver "fullness," respectively, when compared on a calorie-for-calorie basis.

DESIGN

Participants (n = 36) consumed either reduced-energy-dense (374 kcal) or standard-energy-dense (567 kcal) spaghetti Bolognese for lunch over 5 test sessions. During each test session, liking for the spaghetti Bolognese was assessed, together with measures of expected satiety and expected satiation.

RESULTS

Participants in the reduced-energy-dense condition reported a decrease in liking for the spaghetti Bolognese over the test sessions ( approximately 30%), whereas liking in the standard condition remained constant [condition (reduced/standard) x session (1-5) interaction, P < 0.008]. By contrast, both expected satiation and expected satiety remained similar across conditions and test sessions.

CONCLUSIONS

Over time, the pleasantness of a reformulated low-energy-dense food can decrease, and this may undermine its efficacy as a weight-loss product. It remains to be determined whether a longer period of "flavor-nutrient learning" is needed for shifts in expected satiety and expected satiation to be observed.

Intake during repeated exposure to low- and high-energy-dense yogurts by different means of consumption

BACKGROUND

An important question in the regulation of energy intake is whether dietary learning of energy content depends on the food's characteristics, such as texture. Texture might affect the duration of sensory exposure and eating rate.

OBJECTIVE

The objective was to investigate whether a long sensory exposure, due to differences in means of consumption and in viscosity, enhances learned associations between sensory signals and metabolic consequences and hence facilitates energy intake compensation.

DESIGN

A total of 105 healthy young adults with a mean (+/-SD) age of 22 +/- 3 y and a body mass index (in kg/m(2)) of 21.6 +/- 1.7 participated in a parallel intervention in 3 groups: liquid yogurt with a straw (liquid/straw; n = 34), liquid yogurt with a spoon (liquid/spoon; n = 36), or semisolid yogurt with a spoon (semisolid/spoon; n = 35). Novel flavored yogurts were offered ad libitum for breakfast in 2 energy densities: low ( approximately 215 kJ/100 g) and high ( approximately 600 kJ/100 g). Subjects were repeatedly exposed to the yogurt products (10 times), and yogurt intake was measured.

RESULTS

Intakes (P = 0.01) and eating rates (P = 0.01) were highest in the liquid/straw group. Average intakes over 10 exposures were 575 +/- 260 g for liquid/straw, 475 +/- 192 g for liquid/spoon, and 470 +/- 223 g for semisolid/spoon; average eating rates were 132 +/- 83 g/min for liquid/straw, 106 +/- 53 g/min for liquid/spoon, and 105 +/- 88 g/min for semisolid/spoon. No significant interaction for intake between intervention group, energy density, and repeated exposure was observed, and intakes of the low- and high-energy-dense yogurts did not change over time in any of the intervention groups.

CONCLUSIONS

We observed no energy intake compensation after repeated exposure to yogurt products. Differences in ad libitum yogurt intake could be explained by eating rate, which was affected by the different means of consumption. This trial was registered with the Dutch trial registration at http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=1853 as NTR1853.

Familiarity changes expectations about fullness

Expected satiation (the extent to which a food is expected to deliver fullness) is an excellent predictor of self-selected portion size (kcal). Here, we explored the prospect that expected satiation changes over time. Fifty-eight participants evaluated expected satiation in eight test foods (including two 'candidate' foods: sushi and muesli) and reported how often they consumed each food. In one of the candidate foods (sushi), and across other test foods, expected satiation increased with familiarity. Together, these findings are considered in the context of 'satiation drift' - the hypothesis that foods are expected to deliver poor satiation until experience teaches us otherwise.