BMI and explicit-implicit cues on food choice: The fake food buffet in the United Kingdom and Indonesia.

We examined whether people with high BMI sampled from two different countries were more susceptible to behavioural change via an implicit, rather than explicit, intervention. We measured BMI and used three types of cue interventions (implicit vs explicit healthy lifestyle cue vs neutral cue) to examine their impact on our participants' food choice using the Fake Food Buffet. Healthiness of the meal chosen was measured by the percentage of healthy food items in the meal. Portion size of their chosen meal was operationalised by the total number of food items chosen and its total calorie content was also estimated. Participants were recruited from the United Kingdom (N = 264) and Indonesia (N = 264). Our results indicated that while explicit food cues were overall more effective, implicit cues were a more effective strategy to change food choice behaviours among individuals with high BMI. Participants with high BMI were more likely to regulate the healthiness of their meal and less likely to regulate its portion size or calorie content. The efficacy of our healthy eating interventions was cross-culturally generalizable. Our study supports previous research that implicit cues of a healthy lifestyle might be a more effective behavioural change strategy for individuals with high BMI.

The impact of packaging attributes on portion decisions: Consumer values are important.

Research shows that features of food packaging can help to promote healthy food choices. Laboratory-based studies demonstrate that smart design of packaging facilitates portion control. However, the extent to which consumers notice packaging features for portion control is not known. Therefore, this study investigated how individuals interact with food packaging, how they utilise the on-pack serving-size guidelines and how they make portion decisions. To do this, 25 adult participants were recruited to participate in an online semi-structured interview. Data were analysed using thematic analysis until saturation was achieved. Participants reported that they rarely attend to on-pack serving recommendations and indicated some resistance to them. Some structural features (small/single serving, pre-portioned and resealable packaging) were identified as facilitators of portion control. In contrast, the healthiness evaluation of the product from packaging cues was described as a permissive cue to eat more of the product. Participants in this study value their autonomy and control, preferring convenient behavioural choices over recommended portion servings. They also reported future concerns about the effects of their diet on health, but that current context (hunger, convenience) sometimes presented a barrier to healthy eating. Packaging does more than protect its contents, packaging can affect eating decisions to support portion control, and for some, offers permission to overconsume. This study identified ways that participants use packaging to make portion decisions, revealing the role of habits, current context and future health considerations. The interviews revealed the importance of consumer values on food choice in general and portion control in particular. In conclusion, smart food packaging design could use these findings to nudge healthy portion decisions by incorporating consumer values and by recognising consumer needs for habitual, current and future concerns.

Evidence of a self-serving bias in people's attributions for their food intake.

People often fail to acknowledge external influences on their food intake, but there might be some circumstances in which people are willing to report that those external factors influenced their behavior. This study examined whether participants who believed that they had overeaten would indicate that the portion size they were served influenced their food intake. Participants (119 women) ate a pasta lunch at two separate sessions, one week apart. At the second session, participants were randomly assigned to receive either a regular portion of pasta (the same portion as the first session) or a large portion of pasta (a portion that was twice the size), and to receive false feedback about their food intake indicating that they had either eaten about the same as or substantially more than they had at the previous session. Participants were then asked to indicate the extent to which the amount of food served influenced how much they ate at that second session. Compared to participants who were informed that they had eaten the same amount across the two sessions, those who were informed that they ate more at the second session reported a stronger influence of the amount of food served if they also received a large portion of pasta, but not if they received a regular portion of pasta. These findings suggest that the willingness to implicate external influences (e.g., portion size) on one's food intake may be driven by a self-serving bias, providing an "excuse" for overeating. However, the external cue must be salient enough to be a plausible explanation for one's behavior.

Longitudinal associations between psychosomatic and emotional status and selected food portion sizes in European children and adolescents: IDEFICS/I.Family study.

This study aims to investigate the influence of psychosomatic and emotional status on food portion sizes (PSs) consumption from high energy-dense food groups in European children and adolescents. We hypothesized that psychosomatic and emotional status would have a significant association with the PS selection of energy-dense food. The study included 7355 children aged between 2 and 9.9 years at baseline (T0) (48.8% females); 3869 after 2 years (T1) (48.2% females), and 2971 (51.8% females) after 6 years of follow-up (T3). Psychosomatic and emotional status were measured using emotional well-being during the last week score (KINDL) and Strengths and Difficulties Questionnaire. PS was calculated from daily food intake recorded in 24-hour dietary recalls. The associations between emotional status indicators and PS from selected energy-dense food groups were assessed by multilevel linear regression models. In the cross-sectional analysis, we observed that higher KINDL scores were linked to lower PS consumption from sweet bakery products and savory snacks in both genders. Moreover, we found that adolescent females with high emotional and peer problem scores tended to consume larger PS of carbohydrate-rich and sugar-fatty food items (P < .017). Longitudinally, higher peer problem scores were associated with increased PS from bread and rolls, margarine and lipids, and dairy products in all genders and age groups (P< .017). In adolescents, psychosomatic and emotional status could be a trigger for consuming large PS from carbohydrate-rich and sugar-fatty energy-dense foods. Thus, nutritional interventions should consider emotional status to decrease unhealthy dietary habits in children and adolescents.

Breadth of substance use is associated with the selection of a larger food portion size via elevated impulsivity.

Substance use is associated with altered or elevated food consumption and disordered eating. In the present study we examined whether breadth (variety) of drug use was associated with elevated portion size in a general population sample as it was in persons in recovery from substance use disorder. Furthermore, measures of emotional eating, impulsivity, food misuse, food craving were taken as possible mediators and reward responsiveness was examined as a potential moderator of this association. 444 adults (48.6 % women, mean age of 47.8 years) completed an online study in which they were asked to make judgements of ideal portion size for 6 different foods using a validated online tool that allowed participants to adjust the portion size of images of foods. Ideal portion size has been identified as a strong predictor of actual consumption. Participants were also asked to report the number of substances used in the past and provide anthropometric information. The results confirmed that breadth of drug use was associated with selection of higher portion size. Reward responsiveness was not a moderator of this relationship. Of the tested mediators, only impulsivity mediated the association between breadth of drug use and portion size. The results show that impulsivity may underlie the association between eating and substance use.

Children with lower ratings of executive functions have a greater response to the portion size effect.

Deficits in executive functions (EFs), a set of cognitive processes related to self-regulation, are associated with the development of obesity. Prior studies from our group showed that lower food-cue related activation in brain regions implicated in self-regulation was related to a larger portion size effect. We tested the hypothesis that lower EFs in children would be positively related to the portion size effect. Healthy weight children aged 7-8 y (n = 88), who varied by maternal obesity status, participated in a prospective study. At baseline, the parent primarily in charge of feeding completed the Behavior Rating Inventory of Executive Function (BRIEF2) to assess child EFs, including Behavioral (BRI), Emotional (ERI), and Cognitive (CRI) indices. At 4 baseline sessions, children consumed meals in which the portion sizes of foods (pasta, chicken nuggets, broccoli, and grapes) varied by visit (total meal weight of 769, 1011, 1256, or 1492g). Intake increased with increasing portions in a linear trajectory (p < 0.001). EFs moderated the portion size effect such that lower BRI (p = 0.003) and ERI (p = 0.006) were associated with steeper increases in intake as portions increased. As amount of food increased, children in the lowest functioning tertiles for BRI and ERI increased intake by 35% and 36%, respectively, compared to children in the higher tertiles. Increases in intake among children with lower EFs were for higher- but not lower-energy-dense foods. Thus, in healthy weight children who varied by obesity risk, lower parentally reported EFs were associated with a larger portion size effect, and these results were independent of child and parent weight status. Therefore, EFs may be target behaviors that could be strengthened to help children moderate excess intake in response to large portions of energy-dense foods.

Estimation of meal portions in bulimia nervosa compared to anorexia nervosa and healthy controls.

PURPOSE: Bulimia nervosa (BN) and anorexia nervosa (AN) are potentially life-threatening eating disorders (ED) that primarily affect young people, mostly women. The central common pathology is linked to the relationship with food and with abnormalities in food intake. A previous study indicated that individuals with AN tend to overestimate food portion sizes compared to healthy controls (HC), but no study has investigated these patterns in BN, which was the objective of this study. METHODS: Women with BN (27), AN (28), and HC (27) were asked to rate different meal portion sizes in two conditions: as if they were supposed to eat them (intent-to-eat condition) or in general (general condition). BN results were compared to HC and AN using mixed model analyses. RESULTS: BN showed larger estimations compared to HC, while smaller estimations compared to AN. These differences were found mostly for intermediate portion sizes. No difference for conditions (intent-to-eat; general) was found between groups. CONCLUSION: When estimating food portion sizes, individuals with BN seem to fall intermediately between HC and AN. ED symptoms in BN were most strongly associated with higher portion estimation. This might therefore reflect one aspect of the cognitive distortions typically seen also in AN. A therapeutic option could include the frequent visual exposure to increasing portions of food, what may serve to recalibrate visual perceptions of what a "normal-sized" portion of food looks like. LEVEL OF EVIDENCE: Level II: Evidence obtained from well-designed controlled trials without randomization.

Adding more portion-size options to a menu: A means to nudge consumers to choose larger portions of healthy food items.

We propose and find that the extremeness aversion bias when choosing portion-sizes is stronger for healthy food as compared to unhealthy food items. In two studies (and a follow-up) we find that adding an extra-large option to a standard menu of small, medium, and large portions increases the choice share of the larger portion-sizes; but more so for healthy food than for unhealthy food. Furthermore, we find evidence for the lay belief that larger portions of healthy food do not have incremental health costs. When health costs of the larger portions of healthy food were made salient by providing calorie information, the above effects disappeared. These findings show (1) a boundary condition to the extremeness aversion effect when choosing portion sizes, and (2) imply that this bias can act as a nudge to increase the consumption of healthy food.

Portion size can be used strategically to increase intake of vegetables and fruits in young children over multiple days: a cluster-randomized crossover trial.

BACKGROUND: Although dietary guidelines recommend that vegetables and fruits make up half the diet, it is unclear whether serving vegetables and fruits in larger portions will have sustained effects on children's intake over multiple days. OBJECTIVES: This study tested the effects on children's intake of 2 strategies for increasing the proportion of vegetables and fruits: either adding or substituting extra portions as side dishes at meals and snacks over 5 d. METHODS: In a cluster-randomized crossover design with 3 periods, we provided all meals and snacks for 5 d to 53 children aged 3-5 y in classrooms in their childcare centers. In the Control condition, we served typical portions for all food groups. In the Addition condition we increased portions of low-energy-dense vegetables and fruits by 50%, and in the Substitution condition we increased portions of vegetables and fruits by 50% and also reduced portions of other foods by an equivalent weight. RESULTS: For vegetables, the Addition strategy increased daily intake compared with Control by 24% (mean ± SEM = 12 ± 3 g/d; P = 0.0002), and the Substitution strategy increased intake compared with Control by 41% (22 ± 3 g/d; P < 0.0001). For fruits, consumption increased by similar amounts: Addition by 33% (60 ± 6 g/d) and Substitution by 38% (69 ± 8 g/d; both P < 0.0001). Both strategies increased vegetable and fruit intakes compared with Control across all 5 days (all P < 0.004), although the increase in fruit consumption with Addition declined over time (P < 0.0001). Daily energy intake compared with Control increased by 5% with Addition (57 ± 17 kcal; P = 0.001) but decreased by 6% with Substitution (-64 ± 21 kcal; P = 0.004). CONCLUSIONS: Both the Addition and Substitution strategies promoted increases in vegetable and fruit intake over 5 d in preschool children. When excess energy intake is a concern, substituting vegetables and fruits for other foods is a better option than simply serving more.This trial was registered at http://www.clinicaltrials.gov as NCT03242863 (https://clinicaltrials.gov/ct2/show/NCT03242863), where the protocol is available.

Validation of a Web-Based, Time-Use Application to Assess Children's School Meal Intakes: My E-Diary for Activities and Lifestyle (MEDAL).

My E-Diary for Activities and Lifestyle (MEDAL), a web-based application, was developed to assess the diets of children. This study examined the validity of school recess meals reported by children on MEDAL, using meal photography as the reference. Recess meals were photographed by trained researchers, and food items and portion sizes of recess meals reported on MEDAL were compared to recess meal photos. Validity was assessed by percentages of match, omission and intrusion for food items and percentages of the match, underestimation and overestimation for portion sizes. The Mann-Whitney test and the Wilcoxon matched-pairs signed-rank test examined if sex, school and day of recording influenced the validity of food item reporting. We found that participants (n = 33, aged 10-11 years) recalled 60.2% of food items consumed at recess accurately (matches); omissions (24.6%) were more common than intrusions (15.2%). Omissions tended to be side dishes, and intrusions tended to be high-calorie items. Sex, school and day of recording did not influence validity. For food portion sizes, 58.3% of items were accurately reported. Overestimations (33.3%) were more common than underestimations (8.3%). In conclusion, these children were able to report food items consumed during school recess meals using MEDAL, albeit with limitations on the degree of accuracy.

How Do French Parents Determine Portion Sizes for Their Pre-Schooler? A Qualitative Exploration of the Parent-Child Division of Responsibility and Influencing Factors.

Large portion sizes can make children overeat, alter their self-regulation abilities and induce weight gain. However, little is known about how parents determine portion sizes for their children. Using semi-structured interviews with 5 fathers and 32 mothers of pre-schoolers, this study examined French parents' food portioning practices. The division of responsibility between parent and child in deciding portion sizes was explored, as well as the influencing factors and possible sources of information. Parents described a wide range of practices. For most, determining portion sizes is an intuitive action that depends on habits and mainly arises from experiences with feeding their child and his/her appetitive traits. Few parents grant autonomy to their child for portioning and serving food, especially for the first serving. Many influencing factors were identified, including child-related (e.g., appetite, food preferences), parent-related (e.g., avoiding food waste), and external factors (e.g., influence of siblings, French food culture). Most parents do not search for information/recommendations to guide their practices. Stimulating optimal self-regulation of eating in children is important and parents can play a crucial role in this. This study identified barriers and facilitators to guide parents in providing appropriate portion sizes and help include children in this decision process.

Impact of Portion Control Tools on Portion Size Awareness, Choice and Intake: Systematic Review and Meta-Analysis.

Portion control utensils and reduced size tableware amongst other tools, have the potential to guide portion size intake but their effectiveness remains controversial. This review evaluated the breadth and effectiveness of existing portion control tools on learning/awareness of appropriate portion sizes (PS), PS choice, and PS consumption. Additional outcomes were energy intake and weight loss. Published records between 2006-2020 (n = 1241) were identified from PubMed and WoS, and 36 publications comparing the impact of portion control tools on awareness (n = 7 studies), selection/choice (n = 14), intake plus related measures (n = 21) and weight status (n = 9) were analyzed. Non-tableware tools included cooking utensils, educational aids and computerized applications. Tableware included mostly reduced-size and portion control/calibrated crockery/cutlery. Overall, 55% of studies reported a significant impact of using a tool (typically smaller bowl, fork or glass; or calibrated plate). A meta-analysis of 28 articles confirmed an overall effect of tool on food intake (d = -0.22; 95%CI: -0.38, -0.06; 21 comparisons), mostly driven by combinations of reduced-size bowls and spoons decreasing serving sizes (d = -0.48; 95%CI: -0.72, -0.24; 8 comparisons) and consumed amounts/energy (d = -0.22; 95%CI: -0.39, -0.05, 9 comparisons), but not by reduced-size plates (d = -0.03; 95%CI: -0.12, 0.06, 7 comparisons). Portion control tools marginally induced weight loss (d = -0.20; 95%CI: -0.37, -0.03; 9 comparisons), especially driven by calibrated tableware. No impact was detected on PS awareness; however, few studies quantified this outcome. Specific portion control tools may be helpful as potentially effective instruments for inclusion as part of weight loss interventions. Reduced size plates per se may not be as effective as previously suggested.

The Role of Dishware Size in the Perception of Portion Size in Children and Adolescents with Obesity.

PURPOSE: The influence of dishware on portion size perception in children and adolescents is inconclusive. This study investigated how children and adolescents with both obesity and a normal weight perceived portion size in different sized and shaped dishware items. METHODS: The study included 60 children and adolescents with overweight and obesity (OBE) and 27 children and adolescents with normal weight (NW) aged from 9 to 17 years. The participants estimated quantities in three pairs of drinking glasses, one pair of bowls and two pairs of plates which varied in size and shape. The children were instructed to state intuitively which portion they would choose for big or small thirst/hunger. Thereafter they were asked to determine the exact amount by answering which dishware item contained the larger/smaller portion (cognitive evaluation). RESULTS: There were no substantial differences in the intuitive evaluation of portion sizes between OBE and NW. During the cognitive evaluation, OBE estimated the amount of water in the glasses more correctly compared to NW (61% vs. 43%; p = 0.008); OBE estimated the amount of lentils in the bowls and on the plates significantly less correctly (39%) compared to NW (56%; p = 0.013). CONCLUSIONS: Habit formation and environmental stimuli might play a greater role in estimating food amounts in dishware than the child's and adolescent's body weight.

People serve themselves larger portions before a social meal.

One of the most powerful influences on food intake yet identified is the presence of familiar others at an eating occasion: people eat much more when they eat with friends/family than when they eat alone. But why this is the case is unclear. Across two studies (Study 1: N = 98; Study 2: N = 120), we found that the mere anticipation of social interaction is all that is needed to promote the selection of larger meals, and that this occurs even when a person is alone when they make their decision. Adult women served themselves larger portions when they knew they were going to eat socially versus when they knew they were going to eat alone. These data suggest that how other people influence our food intake reaches beyond the specific eating context to affect pre-meal portion size decisions, suggesting that a fundamental shift is required in our thinking about social influences on eating.

Can Visual Cues to Portion Size Reduce the Number of Portions of Consumed? Two Randomized Controlled Trials.

BACKGROUND: Since 1950, the portion size of many snack foods has more than doubled and obesity rates have tripled. Portion size determines energy intake, often unwittingly. PURPOSE: This paper tests whether salient visual cues to portion size on the packaging of high fat, sugar, or salty (HFSS) snacks can reduce consumption. METHODS: Two preregistered randomized controlled trials (N = 253 and N = 674) measured consumption in a lab and the home environment. Cues were salient, labeled stripes that demarcated single portions. Participants were randomized to cue condition or control. Consumption was measured without awareness. RESULTS: The main preregistered effect of the visual cue was not statistically significant. There was some variation by subgroup. In Study 1, men were more likely to eat the whole can of potato chips than women but significantly reduced consumption when visual cues were on the pack. The effect size was large: the number of men eating more than the recommended portion fell by 33%. Study 2 monitored household consumption of chocolate biscuits (cookies) sent to family homes in gift packs. Again, the main effect was nonsignificant but there was significant subgroup variation. When the person receiving the biscuits was female, households were more likely to eat more than the recommended portion per person per day, but less likely when the visual cues were displayed. The gender of the eaters was not known. The effect size was again large: the number of households eating more than the recommended portion fell by 26%. Households with children were also less likely to open packs with visual cues compared to control packs. Both studies recorded significant increases in the likelihood of observing serving size information, together with confusion about what it means. CONCLUSIONS: The studies offer some evidence that salient visual cues could play a role in tackling the high consumption of unhealthy snacks, but the effects are confined to specific subgroups and warrant further investigation.

How do patients with eating disorders perceive and evaluate food portion sizes? A systematic review.

OBJECTIVE: The selection of adequate portion sizes plays a key role in the nutritional treatment of eating disorders (EDs). There is limited knowledge concerning the estimation of portion sizes in individuals with EDs. METHOD: We performed a systematic review according to the PRISMA statement to synthesise current evidence in this field. Of N = 584 hits, four full-texts were included in the qualitative synthesis. RESULTS: While patients with anorexia nervosa (AN) tend to overestimate the size of energy-dense food items and small to medium sized meal portions, they do not show a different estimation compared to healthy controls when judging the amount of food pieces. Large portion sizes were associated with increased anxiety in patients with AN. DISCUSSION: The overestimation of food portion sizes seems to be driven by attitudinal and/or higher cognitive factors associated with AN. Differences between the studies are discussed and suggestions for future studies are given.

Effects of snack portion size on anticipated and experienced hunger, eating enjoyment, and perceived healthiness among children.

BACKGROUND: Large portion sizes encourage overconsumption. Prior studies suggest that this may be due to errors in anticipating the effects of portion size, although the studies were limited to adults and energy-dense foods. OBJECTIVE: Our aim was to investigate potential anticipation errors related to the effects of portion size on hunger, eating enjoyment, and healthiness ratings among 8-to-11-year-old children, for snacks differing in energy density and healthiness perception, and as a function of initial hunger. METHODS: In a within-subject design, 83 children aged 8 to 11 years old were first asked to anticipate how much they would enjoy, how hungry they would feel after eating, and how healthy it would be to eat a recommended serving size, a 50% larger portion, and a 125% larger portion of brownie or applesauce. Over six subsequent sessions, the children were asked to eat all of each of these portions and then rate their post-intake enjoyment, residual hunger, and healthiness perceptions. We also measured hunger at the beginning of each session. RESULTS: For both snacks, larger portions reduced anticipated and experienced residual hunger similarly. In contrast, larger portions increased anticipated but not experienced eating enjoyment for both snacks; although larger portions increased anticipated and experienced enjoyment ratings among extremely hungry children. All children under-anticipated how much they would enjoy the smaller portion sizes. Healthiness ratings were unaffected by portion size for both snacks but differed across foods (applesauce vs. brownie). CONCLUSIONS: Children anticipate the effects of portion size on hunger change accurately, overestimate the effects of portion size on eating enjoyment, and rate food healthiness on food type and not portion size. Helping children better anticipate the enjoyment from smaller (recommended) portion sizes and understand that food quantity, not just quality, matters for healthy eating may be a solution to improve portion control.

Portion size selection in children: Effect of sensory imagery for snacks varying in energy density.

Food sensory imagery - creating a vivid mental image of the sensory experience of eating - can lead to the selection of smaller portions because it serves as a reminder that eating enjoyment does not necessarily increase with portion size. The evidence is mostly limited to adults and to energy-dense foods for which it is particularly difficult to predict the satiating effects of consumption quantity. The objective was to study how food sensory imagery influences portion size selection of foods varying in energy density (brownie and applesauce) by 7- to 11-year-old children. During after-school time, 171 children were randomized into two conditions. Children in the food sensory imagery condition were asked to imagine the taste, smell, and texture of eating palatable foods, i.e., chocolate cereal, chocolate waffle, and chocolate candies. Children in the control condition performed a similar sensory imagery task for non-food-related activities. Children were then asked to choose between the recommended serving size, a 50% larger portion, and a 125% larger portion of either brownie or applesauce. One week later, they were placed in the same condition for the other food. Compared to the control condition, food sensory imagery led children to choose 7.1% less brownie but had no effect on applesauce portion selection. Exploratory findings showed that the food sensory imagery intervention was especially effective at reducing brownie portion size selection among children who were moderately hungry, who usually eat fast, and whose parents pressure them to eat. In conclusion, food sensory imagery may be a useful intervention to nudge children towards healthier portion size choices because it reduces the selected portion size of an energy-dense snack without reducing the selected portion size of a healthier snack.

Reductions to main meal portion sizes reduce daily energy intake regardless of perceived normality of portion size: a 5 day cross-over laboratory experiment.

BACKGROUND: Smaller portions may help to reduce energy intake. However, there may be a limit to the magnitude of the portion size reduction that can be made before consumers respond by increasing intake of other food immediately or at later meals. We tested the theoretical prediction that reductions to portion size would result in a significant reduction to daily energy intake when the resulting portion was visually perceived as 'normal' in size, but that a reduction resulting in a 'smaller than normal' portion size would cause immediate or later additional eating. METHODS: Over three 5-day periods, daily energy intake was measured in a controlled laboratory study using a randomized crossover design (N = 30). The served portion size of the main meal component of lunch and dinner was manipulated in three conditions: 'large-normal' (747 kcal), 'small-normal' (543 kcal), and 'smaller than normal' (339 kcal). Perceived 'normality' of portion sizes was determined by two pilot studies. Ad libitum daily energy intake from all meals and snacks was measured. RESULTS: Daily energy intake in the 'large-normal' condition was 2543 kcals. Daily energy intake was significantly lower in the 'small-normal' portion size condition (mean difference - 95 kcal/d, 95% CI [- 184, - 6], p = .04); and was also significantly lower in the 'smaller than normal' than the 'small-normal' condition (mean difference - 210 kcal/d, 95% CI [- 309, - 111], p < .001). Contrary to predictions, there was no evidence that the degree of additional food consumption observed was greater when portions were reduced past the point of appearing normal in size. CONCLUSIONS: Reductions to the portion size of main-meal foods resulted in significant decreases in daily energy intake. Additional food consumption did not offset this effect, even when portions were reduced to the point that they were no longer perceived as being normal in size. TRIAL REGISTRATION: Prospectively registered protocol and analysis plan: https://osf.io/natws/; retrospectively registered: https://clinicaltrials.gov/ct2/show/NCT03811210.

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.