Current appetite influences relative differences in the expected satiety of foods for momentary, but not hypothetical, expected satiety assessments.

Research has shown that expected satiety is highly associated with portion-size selection and can vary (kcal-for-kcal) significantly between foods. However, research has not adequately investigated whether current appetite influences relative differences in the expected satiety of foods. This is important to explore to better understand how current motivational state influences food choice and portion selection. This study used 'hypothetical' and 'momentary' expected-satiety assessments to understand whether methods requiring a reflection on current motivational state [momentary] versus more hypothetical considerations when assessing expected satiety can influence the interpretation of results. It was hypothesised that current appetite would only influence relative differences in expected satiety between foods for momentary, but not hypothetical, expected satiety assessments. Participants (n = 54) were shown images of twelve foods, once when hungry and once when full. In each case, they selected a portion for each food to 1) match the expected satiety of a fixed-portion 'standard' food [hypothetical], and 2) stave off hunger until their next meal [momentary]. Results showed that the relative between-food comparison of expected satiety was stable for hypothetical (p=.73) but not momentary assessments (p<.001) suggesting that while current motivational state may influence food choice and portion selection in the moment, more generalised comparisons of the satiating abilities of foods (learned over a longer period) remain stable. This is important 1) for methods in future studies, as immediate dietary intake does not appear to influence hypothetical expected satiety, thus dietary control is not necessary before participants undertake these assessments, and 2) as it confirms that difficulties associated with dietary regulation may not be due to inaccurate hypothetical judgements about foods, but instead appear to be influenced by contextual nuances that occur in the moment.

Development and validation of a new methodological platform to measure behavioral, cognitive, and physiological responses to food interventions in real time.

To fully understand the causes and mechanisms involved in overeating and obesity, measures of both cognitive and physiological determinants of eating behavior need to be integrated. Effectively synchronizing behavioral measures such as meal micro-structure (e.g., eating speed), cognitive processing of sensory stimuli, and metabolic parameters, can be complex. However, this step is central to understanding the impact of food interventions on body weight. In this paper, we provide an overview of the existing gaps in eating behavior research and describe the development and validation of a new methodological platform to address some of these issues. As part of a controlled trial, 76 men and women self-served and consumed food from a buffet, using a portion-control plate with visual stimuli for appropriate amounts of main food groups, or a conventional plate, on two different days, in a random order. In both sessions participants completed behavioral and cognitive tests using a novel methodological platform that measured gaze movement (as a proxy for visual attention), eating rate and bite size, memory for portion sizes, subjective appetite and portion-size perceptions. In a sub-sample of women, hormonal secretion in response to the meal was also measured. The novel platform showed a significant improvement in meal micro-structure measures from published data (13 vs. 33% failure rate) and high comparability between an automated gaze mapping protocol vs. manual coding for eye-tracking studies involving an eating test (ICC between methods 0.85; 90% CI 0.74, 0.92). This trial was registered at Clinical Trials.gov with Identifier NCT03610776.

The influence of expected satiety on portion size selection is reduced when food is presented in an 'unusual' meal context.

Research shows that expected satiety is highly correlated with ideal portion size, however this correspondence has not been explored when a food is presented in an 'unusual' (incongruous) meal context. This study's aim was to explore whether expected satiety influences portion selection to the same extent in both congruous and incongruous meal contexts. Forty participants completed two trials (one at breakfast and one at lunch) on separate days in a randomised counterbalanced order. They completed measures of expected satiety and ideal portion size for four typical breakfast foods and four typical lunch foods, using a bespoke computer program. Our results showed a significant difference between expected satiety and ideal portion size for lunch foods presented at breakfast time (an incongruous meal context; t(39) = 2.95, p = 0.02). There was no significant difference between expected satiety and ideal portion size in the other incongruous meal context (breakfast foods at lunch; t(39) = 2.10, p = 0.17) or in congruous meal contexts (breakfast foods at breakfast time, lunch foods at lunch time; both t(39) ≤ -0.15, p > 0.999). These results suggest that expected satiety does not have as strong an influence on portion selection when food is presented in an unusual context. Furthermore, in such contexts, smaller portions were selected 1) to stave off hunger until the next meal and 2) as ideal portions compared to in more usual meal contexts. Research is warranted to explore this finding further to understand its implications for weight management.

Protein for Life: Towards a focussed dietary framework for healthy ageing.

'Ageing well' has been highlighted as an important research area by the World Health Organization. In the UK, healthy ageing has been identified as a priority research area by multiple Research Councils and is a key NHS priority. Sarcopaenia, the decline of muscle mass/strength and a key component of healthy ageing, can have a major impact on quality of life and is associated with premature mortality. Increasing protein intake at all stages of the life course may help to reduce the rate of muscle decline and the onset of associated health conditions. However, there is a lack of understanding of the social, demographic and psychological drivers of food choices surrounding protein intake. This report describes the multidisciplinary approach that has been adopted by the Protein for Life project to create a framework for the development of palatable, cost-effective higher-protein foods suitable for an ageing population.

Parental beliefs about portion size, not children's own beliefs, predict child BMI.

BACKGROUND: Increases in portion size are thought by many to promote obesity in children. However, this relationship remains unclear. Here, we explore the extent to which a child's BMI is predicted both by parental beliefs about their child's ideal and maximum portion size and/or by the child's own beliefs. METHODS: Parent-child (5-11 years) dyads (N = 217) were recruited from a randomized controlled trial (n = 69) and an interactive science centre (n = 148). For a range of main meals, parents estimated their child's 'ideal' and 'maximum tolerated' portions. Children completed the same tasks. RESULTS: An association was found between parents' beliefs about their child's ideal (ß = .34, p < .001) and maximum tolerated (ß = .30, p < .001) portions, and their child's BMI. By contrast, children's self-reported ideal (ß = .02, p = .718) and maximum tolerated (ß = -.09, p = .214) portions did not predict their BMI. With increasing child BMI, parents' estimations aligned more closely with their child's own selected portions. CONCLUSIONS: Our findings suggest that when a parent selects a smaller portion for their child than their child self-selects, then the child is less likely to be obese. Therefore, public health measures to prevent obesity might include instructions to parents on appropriate portions for young children.

Obese and overweight individuals are less sensitive to information about meal times in portion-size judgements.

BACKGROUND: Obesity is related to a tendency to discount the future. Information regarding inter-meal interval (IMI) allows meal planning. We sought to assess how obese, overweight and lean people select portion sizes based on the length of an IMI. We hypothesised that individuals with a high body mass index (BMI) would discount information about the IMI. In addition, we investigated how reduced sensitivity to IMIs relates to monetary temporal discounting. METHODS: Participants (lean, n=35; overweight, n=31; obese, n=22) selected lunchtime portion sizes in response to information about the timings of their next meal. In seven trials, the time of the IMI was systematically manipulated, ranging from 'right now' to '8 h'. Participants then completed a monetary temporal discounting task. BMI was included as a continuous measure. For each participant, we conducted a linear regression of portion size on IMI to yield a gradient that reflected reduced sensitivity to future meal timings. RESULTS: As expected, participants selected larger portion sizes in response to a long IMI. Consistent with our hypothesis, individuals with a high BMI discounted information about the IMI (ß=-3.49, P=0.015; confidence interval (CI) 6.29 to -0.70). Monetary discounting also negatively predicted BMI (ß=-8.1, P=0.003; CI=-13.43 to -2.77), but did not correlate with IMI sensitivity (P>0.05). CONCLUSIONS: These results are the first to demonstrate that temporal discounting operates in planning from one meal to the next, and is more prevalent in obese and overweight, relative to lean individuals. Participants with a high BMI discounted concerns about potential future fullness and hunger in the IMI. Our observations might begin to explain associations between obesity and irregular meal timings or help to form the basis for a targeted intervention that promotes future thinking in meal planning.

Disinhibited eating mediates differences in attachment insecurity between bariatric surgery candidates/recipients and lean controls.

Previous research has shown that attachment anxiety is a good predictor of body mass index. This relationship is significantly mediated by disinhibited (over-) eating and is likely to reflect a specific form of affect regulation. This study explored whether obese bariatric surgery candidates (BSC; N=34) and bariatric surgery recipients (BSR; N=15) would show higher levels of attachment insecurity (higher attachment anxiety and/or higher attachment avoidance) than a group of age and gender-matched lean controls (N=54). Mediation analyses showed that compared to lean controls (M=2.96, SE=0.1), both BSC (M=3.5, SE=0.2) and BSR (M=3.4, SE=0.2) groups had a more insecure attachment orientation. These relationships were significantly mediated by disinhibited eating (BSC: lower limit confidence interval (LLCI)=0.06 and upper limit confidence interval (ULCI)=0.62; BSR: LLCI=0.02 and ULCI=0.76). There was no such relationship when the BSC and BSR groups were compared (LLCI=-0.15 & ULCI=0.3). These observations suggest that attachment insecurity may be a risk factor for obesity and bariatric surgery because of associated disinhibited eating. Moreover, these factors may be important to consider when bariatric surgery results in poor outcomes.

Elasticity in portion selection is predicted by severity of anorexia and food type in adolescents.

The size of portions that people select is an indicator of underlying mechanisms controlling food intake. Fears of eating excessive portions drive down the sizes of portions patients with anorexia nervosa (AN) can tolerate eating significantly below those of healthy controls (HC) (Kissileff et al., 2016). To determine whether patients with AN will also reduce the sizes of typical or ideal portions below those of controls, ANOVA was used to compare maximum tolerable, typical, and ideal portions of four foods (potatoes, rice, pizza, and M&M's) in the same group of 24 adolescent AN patients and 10 healthy adolescent controls (HC), on which only the maximal portion data were previously reported. Typical and ideal portion sizes did not differ on any food for AN, but for HC, typical portions sizes (kcals) became larger than ideal as the energy density of the food increased, and were significant for the most energy dense food. Ideal portions of low energy dense foods were the same for AN as for in HC. There was a significant 3-way (group × food × portion type) interaction, such that HC selected larger maximum than typical portions only for pizza. We therefore proposed that individuals of certain groups, depending on the food, can be flexible in the amounts of food chosen to be eaten. We call this difference between maximum-tolerable, and typical portion sizes selected "elasticity." Elasticity was significantly smaller for AN patients compared to HC for pizza and was significantly inversely correlated with severity of illness. This index could be useful for clinical assessment of AN patients, and those with eating problems such as in obesity and bulimia nervosa and tracking their response to treatment.

Computerized measurement of anticipated anxiety from eating increasing portions of food in adolescents with and without anorexia nervosa: Pilot studies.

Dieting and excessive fear of eating coexist in vulnerable individuals, which may progress to anorexia nervosa [AN], but there is no objective measure of this fear. Therefore, we adapted a computer program that was previously developed to measure the satiating effects of foods in order to explore the potential of food to induce anxiety and fear of eating in adolescent girls. Twenty four adolescents (AN) and ten healthy controls without eating disorders rated pictures of different types of foods in varying sized portions as too large or too small and rated the expected anxiety of five different portions (20-320 kcal). Two low energy dense (potatoes and rice) and two high energy dense (pizza and M&Ms) foods were used. The regression coefficient of line lengths (0-100 mm) marked from "No anxiety" to "this would give me a panic attack", regressed from portions shown, was the measure of "expected anxiety" for a given food. The maximum tolerated portion size [kcal] (MTPS), computed by method of constant stimulus from portions shown, was significantly smaller for high energy dense foods, whereas the expected anxiety response was greater, for all foods, for patients compared to controls. For both groups, expected anxiety responses were steeper, and maximum tolerated portion sizes were larger, for low, than high, energy dense foods. Both maximum tolerated portion size and expected anxiety response were significantly predicted by severity of illness for the patients. Those who had larger maximum tolerated portion sizes had smaller anticipated anxiety to increasing portion sizes. Visual size had a greater influence than energy content for these responses. This method could be used to quantify the anxiety inducing potential of foods and for studies with neuro-imaging and phenotypic clarifications.

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.

'I just can't help myself': effects of food-cue exposure in overweight and lean individuals.

OBJECTIVE: Even brief exposure to the sight and smell of food has been shown to increase reported appetite, initiate 'cephalic phase responses,' and increase planned and actual consumption. This experiment tested the hypothesis that overweight individuals are especially sensitive to these established effects of food-cue exposure. DESIGN: Overweight (n = 52) and normal-weight (n = 52) participants were exposed to the sight and smell of a 'cued' food (pizza) for 60 s. Before and after this period, we assessed salivation, prospective (planned) portion size, and desire to eat pizza and other 'non-cued' foods. Participants were then offered ad libitum access to pizza. RESULTS: Consistent with previous studies, food-cue exposure increased rated hunger and desire to eat, increased prospective portion size of all savory foods, and increased salivation. In overweight individuals, cue exposure (i) elicited a significantly greater salivary response and, (ii) evoked a significantly greater increase in desire to eat both the cued food and another non-cued food. CONCLUSION: After cue exposure, overweight individuals experience a greater motivation to consume food but do not desire or consume greater amounts of food. These findings are consistent with evidence that snacking and meal variability predict weight gain and they expose 'cue reactiveness' as a potential predisposing factor for overweight.

Attachment anxiety, disinhibited eating, and body mass index in adulthood.

Several studies report a relationship between body mass index (BMI) and disinhibited eating (a failure to restrict intake and to overeat). However, the aetiology of disinhibited eating has received scant attention. In this study, we consider a role for 'attachment orientation', a trait that reflects the quality of bonding in early life and remains stable throughout adulthood. Participants (N = 200, females = 135, BMI range from 17.4 to 41.1 kg m(-2)) completed measures of disinhibition and attachment orientation. 'Attachment anxiety' was a good predictor of disinhibited eating (P<0.001). Furthermore, mediation analysis confirmed that it is through this relationship that attachment anxiety also predicts BMI (P=0.02). These findings are consistent with other studies, showing an association between attachment orientation and other disinhibited behaviours, including alcohol and substance abuse. Our interpretation is that disinhibited eaters engage in external affect regulation. In doing so, they seek to mitigate the anxiety associated with poor interpersonal attachments.

Potential early-life predictors of dietary behaviour in adulthood: a retrospective study.

OBJECTIVE: Unnecessary dietary restraint (ie in the absence of a need to lose weight) and chronic overeating are both very unhealthy activities. As a precursor to a more involved longitudinal study, we sought to identify potential early-life predictors that merit scrutiny in this context. DESIGN: Four retrospective questionnaire studies were conducted (Study 1, N=242; Study 2, N=297; Study 3, N=175; Study 4, N=261). Female participants (18-30 y) completed measures of current dietary restraint and overeating. They also recalled experiences between 5 and 10 years of age. All were staff or students at Loughborough University (UK). RESULTS: After considering obvious sources of systematic bias, we report evidence that (i) dietary restraint is related to memories of maternal weight and dietary behaviour, and (ii) overeating and meal-size selection are both associated with memories of receiving a high-energy diet. CONCLUSION: The role of maternal factors in dietary restraint is consistent with previous research exploring the early onset of this behaviour. However, the relationship between childhood diet and overeating has not been suggested elsewhere. This is particularly important because it suggests a previously unreported correspondence between childhood experience and behaviours associated with obesity in adulthood.

Effects of asynchrony and ear of presentation on the pitch of mistuned partials in harmonic and frequency-shifted complex tones.

When a partial of a periodic complex is mistuned, its change in pitch is greater than expected. Two experiments examined whether these partial-pitch shifts are related to the computation of global pitch. In experiment 1, stimuli were either harmonic or frequency-shifted (25% of F0) complexes. One partial was mistuned by +/- 4% and played with leading and lagging portions of 500 ms each, relative to the other components (1 s), in both monaural and dichotic contexts. Subjects indicated whether the mistuned partial was higher or lower in pitch when concurrent with the other components. Responses were positively correlated with the direction of mistuning in all conditions. In experiment 2, stimuli from each condition were compared with synchronous equivalents. Subjects matched a pure tone to the pitch of the mistuned partial (component 4). The results showed that partial-pitch shifts are not reduced in size by asynchrony. Similar asynchronies are known to produce a near-exclusion of a mistuned partial from the global-pitch computation. This mismatch indicates that global and partial pitch are derived from different processes. The similarity of the partial-pitch shifts observed for harmonic and frequency-shifted stimuli suggests that they arise from a grouping mechanism that is sensitive to spectral regularity.

Effects of dietary restraint on flavour-flavour learning.

Flavour preference learning in 21 restrained and 21 unrestrained females was explored using an evaluative conditioning paradigm. Each participant was exposed to an adapted version of the procedure used by Johnsrude et al., (1999, Learning & Motivation30, 250-264). During conditioning, participants sampled 10 instances each of three novel flavours presented in a semi-randomized order. After sampling a flavour they were instructed to eat a sweet according to three different flavour-reinforcement contingencies. One flavour was accompanied by a sweet on 90% of trials and was presented alone on 10% of the trials, while the remaining flavours were rewarded at ratios 50% : 50% and 10% : 90%, respectively. The conditioning phase occurred in conjunction with a counting task requiring continuous use of working memory, and was immediately followed by the participants making hedonic ratings of each flavour. Very few participants showed awareness of the purpose of the experiment or the specific reward contingencies. Despite this, the ratings given by the unrestrained eaters were highly correlated with the reward ratio experienced during conditioning. In contrast, restrained eaters exhibited no evidence for evaluative learning. These findings may explain the equivocal nature of results from previous studies of positive flavour-flavour learning (FFL) and may offer a novel theoretical context within which to study dietary restraint.

Perceptual fusion and fragmentation of complex tones made inharmonic by applying different degrees of frequency shift and spectral stretch.

Global pitch depends on harmonic relations between components, but the perceptual coherence of a complex tone cannot be explained in the same way. Instead, it has been proposed that the auditory system responds to a common pattern of equal spacing between components, but is only sensitive to deviations from this pattern over a limited range [Roberts and Brunstrom, J. Acoust. Soc. Am. 104, 2326-2338 (1998)]. This hypothesis predicts that spectral fusion will be largely unaffected either by frequency shifting a harmonic stimulus (because equal spacing is preserved), or by small degrees of spectral stretch (because significant deviations from equal spacing only cumulate over large spectral distances). Complex tones were either shifted by 0%-50% of F0 (200 Hz+/-10%) or stretched by 0%-12% of F0 (100 Hz+/-10%). Subjects heard a complex followed by a pure tone in a continuous loop. One of the components 2-11 was mistuned by +/- 4%, and subjects adjusted the pure tone to match its pitch. Broadly consistent with our hypothesis, frequency shifts had relatively little effect on hit rates and only large degrees of stretch reduced them substantially. The implications for simultaneous grouping are explored with reference to an autocorrelation model of auditory processing.

Separate mechanisms govern the selection of spectral components for perceptual fusion and for the computation of global pitch.

The perceptual fusion of harmonics is often assumed to result from the operation of a template mechanism that is also responsible for computing global pitch. This dual-role hypothesis was tested using frequency-shifted complexes. These sounds are inharmonic, but preserve a regular pattern of equal component spacing. The stimuli had a nominal fundamental (F0) frequency of 200 Hz (+/- 20%), and were frequency shifted either by 25.0% or 37.5% of F0. Three consecutive components (6-8) were removed and replaced with a sinusoidal probe, located at one of a set of positions spanning the gap. On any trial, subjects heard a complex tone followed by an adjustable pure tone in a continuous loop. Subjects were well able to match the pitch of the probe unless it corresponded with a position predicted by the spectral pattern of the complex. Peripheral factors could not account for this finding. In contrast, hit rates were not depressed for probes positioned at integer multiples of the F0(s) corresponding to the global pitch(es) of the complex, predicted from previous data [Patterson, J. Acoust. Soc. Am. 53, 1565-1572 (1973)]. These findings suggest that separate central mechanisms are responsible for computing global pitch and for the perceptual grouping of partials.

The role of mouth state in the termination of drinking behavior in humans.

Drinking behavior produces a reduction in the unpleasant dry-mouth sensations that accompany thirst. However, it is unclear whether or not the termination of drinking behavior is governed by a mechanism that meters this process. Twenty-two participants were tested in both a "dry mouth" and a control condition. In the dry-mouth condition, they exercised for 20 min. Participants then placed two cotton-wool rolls in each cheek, adjacent to the upper and the lower teeth with the mouth closed, and then drank water through a straw until they felt satiated. The control condition was identical except that participants placed only a single roll in each cheek, adjacent to the lower teeth. Pilot testing confirmed that using two rolls in each cheek reduced saliva volume in the main oral cavity more effectively than one roll. In both conditions, thirst increased after exercise. However, intake volumes, the number of drinking bouts, and the duration of the drinking episodes, were significantly greater in the dry-mouth condition (means; episode = 93.8 s, bouts = 7.0, volume = 428 mL) than in the control condition (means; episode = 69.3 s, bouts = 4.7, volume = 300 mL). These findings suggest that the termination of drinking behavior is governed by changes in mouth dryness. More specifically, saliva production increases during drinking, and this attenuates the need to continue drinking to relieve mouth dryness.

Profiling the perceptual suppression of partials in periodic complex tones: further evidence for a harmonic template.

The basis for the perceptual cohesion of periodic complex tones was investigated. In experiment 1, 2-4 consecutive components (harmonics 6 and above) were removed from a 14-harmonic complex and replaced with a sinusoidal "probe," located at one of a set of regularly spaced positions spanning the gap. On each trial, subjects heard a complex tone followed by an adjustable pure tone in a continuous loop. Subjects were better able to match the pure tone to the probe when the probe did not coincide with a harmonic position. Minima in "hit rate" were more pronounced when harmonic probes were in positions adjacent to other harmonics than when they were not. These findings suggest that the pitch of each in-tune partial was actively suppressed by a template whose influence attenuated with distance from regions of consecutive harmonics. In experiment 2, the partials on either side of the spectral gap were harmonics of different fundamental frequencies. Hit-rate minima corresponding to both fundamentals were found, indicating an upward and downward spread of suppression, and also demonstrating the concurrent operation of two templates. The results confirm recent findings in support of template models, and are consistent with the idea that partial-pitch suppression underpins harmonic fusion.

Perceptual segregation and pitch shifts of mistuned components in harmonic complexes and in regular inharmonic complexes.

It is unclear whether the perceptual segregation of a mistuned harmonic from a periodic complex tone depends specifically on harmonic relations between the other components. A procedure used previously for harmonic complexes [W. M. Hartmann et al., J. Acoust. Soc. Am. 88, 1712-1724 (1990)] was adapted and extended to regular inharmonic complexes. On each trial, subjects heard a 12-component complex followed by a pure tone in a continuous loop. In experiment 1, a mistuning of +/- 4% was applied to one of the components 2-11. The complex was either harmonic, frequency shifted, or spectrally stretched. Subjects adjusted the pure tone to match the pitch of the mistuned component. Near matches were taken to indicate segregation, and were almost as frequent in the inharmonic conditions as in the harmonic case. Also, small but consistent mismatches, pitch shifts, were found in all conditions. These were similar in direction and size to earlier findings for harmonic complexes. Using a range of mistunings, experiment 2 showed that the segregation of components from regular inharmonic complexes could be sensitive to mistunings of 1.5% or less. These findings are consistent with the proposal that aspects of spectral regularity other than harmonic relations can also influence auditory grouping.