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.

Wine glass size and wine sales: four replication studies in one restaurant and two bars.

OBJECTIVE: Previous research suggests that wine glass size affects sales of wine in bars, with more wine purchased when served in larger glasses. The current four studies, conducted in one restaurant (Studies 1 and 2) and two bars (Studies 3 and 4) in Cambridge, England, aim to establish the reproducibility of this effect of glass size on sales. A multiple treatment reversal design was used, involving wine being served in sequential fortnightly periods in different sized glasses of the same design (290 ml, 350 ml, and 450 ml). The primary outcome was daily wine volume (ml) sold. RESULTS: Restaurant: Daily wine volume sold was 13% (95% CI 2%, 24%) higher when served with 350 ml vs. 290 ml glasses in Study 1. A similar direction of effect was seen in Study 2 (6%; 95% CI - 1%, 15%). Bars: Daily wine volume sold was 21% (95% CI 9%, 35%) higher when served with 450 ml vs. 350 ml glasses in Study 3. This effect was not observed in Study 4 (- 7%, 95% CI - 16%, 3%). Meaningful differences were not demonstrated with any other glass comparison. These results partially replicate previous studies showing that larger glasses increase wine sales. Considerable uncertainty remains about the magnitude of any effect and the contexts in which it might occur. Trial registration Study 1: ISRCTN17958895 (21/07/2017), Study 2: ISRCTN17097810 (29/03/2018), Study 3 and 4: ISRCTN39401124 (10/05/2018).

Lower socioeconomic status is associated with higher intended consumption from oversized portions of unhealthy food.

Socioeconomic status is one of the strongest predictors of obesity, and of living in deprived neighbourhoods with unhealthy food environments. Little is known, however, about the psychological processes that translate features of such environments into socioeconomic differences in eating behaviour. One important feature of unhealthy food environments is the prevalence of oversized portions of unhealthy food. The present study tested whether individuals with lower socioeconomic status intend to consume more from large portions than those with higher socioeconomic status, and examined the psychological processes underlying this effect. A large-scale online experiment was conducted in which participants (N = 511) indicated how much they would eat from small and large portions of healthy and unhealthy snacks. The mediating effects of trait impulsivity and perceptions of how much was considered appropriate to eat were also assessed. Participants with lower socioeconomic status intended to eat more from the large portions than from the small portions of the unhealthy snacks, which would equate to a potential 15-22% increase in energy intake. These effects were partially mediated by trait impulsivity and perceptions of how much is appropriate to eat. These findings point to a significant health burden of low socioeconomic status: when exposed to unhealthy food environments, specific psychological processes might increase the amount of unhealthy food those with lower socioeconomic intend to consume. This study critically informs the emerging understanding of the psychology of socioeconomic status and eating behaviour.

Personal relative deprivation increases self-selected portion sizes and food intake.

Cues and experiences of the deprivation of financial/material resources have been associated with increased caloric intake and risk for overweight/obesity. Given that social comparisons may serve as a powerful reference for the adequacy of one's standing and resources, the present research tested whether subjective feelings of personal relative deprivation (PRD) or "losing out" to others stimulates calorie selection and intake. Study 1 demonstrated that self-reported chronic experiences of PRD positively predicted calories selected for a portion and consumed during an ad-libitum meal. Study 2 revealed that experimentally-induced PRD resulted in an increase in the amount of calories selected on a portion selection task and a stronger desire to consume the foods. Consequently, these findings demonstrate that chronic and acute subjective deprivation of non-food resources may contribute to socioeconomic gradients in obesity, and that perceived social inequality may have inherently obesogenic properties that promote excess calorie intake.

What makes people leave their food? The interaction of personal and situational factors leading to plate leftovers in canteens.

In order to provide a basis for the reduction of food losses, our study analyzes individual food choice, eating and leftover behavior in a university canteen by consideration of personal, social and environmental determinants. Based on an extended literature review, a structural equation model is derived and empirically tested for a sample of 343 students. The empirical estimates support the derived model with a good overall model fit and sufficient R2 values for dependent variables. Hence, our results provide evidence for a general significant impact of behavioral intention and related personal and social determinants as well as for the relevance of environmental/situational determinants such as portion sizes and palatability of food for plate leftovers. Moreover, we find that environmental and personal determinants are interrelated and that the impact of different determinants is relative to perceived time constraints during a visit of the university canteen. Accordingly, we conclude that simple measures to decrease avoidable food waste may take effects via complex and interrelated behavioral structures and that future research should focus on these effects to understand and change food leftover behavior.

"We don't snack": Attitudes and perceptions about eating in-between meals amongst caregivers of young children.

OBJECTIVE: Little is known about caregiver attitudes and perceptions towards snacking by toddlers and preschool children outside of the U.S. This qualitative study examined caregiver attitudes and perceptions towards the provision of both foods and beverages in-between meals, along with what constitutes a snack, or snacking occasion, amongst Swiss caregivers. STUDY DESIGN, SETTING AND PARTICIPANTS: This qualitative study used in-depth interviews (n = 17) conducted with caregivers (16 = female, 3 = male, ages = 20-46y, low to high income). The "Food Choice Process Model" was used as a theoretical framework. Interviews explored experiences, attitudes and perceptions about the provision of foods and beverages to children (1-5y) in-between meals. Interview transcripts underwent a thematic analysis and key themes were developed from the data. RESULTS: Five key themes were identified; 1) Timing is everything 2) Location + food type = snacking 3) Snacks are junk 4) Snacks are small 5) Not in front of the children. The clock-time at which young children were fed, the location, the food type and the portion size delineated how caregivers conceptualised snacking. Feeding children at 10am and 4pm was not viewed as snacking, nor was providing milk before bedtime. CONCLUSIONS AND IMPLICATIONS: Eating in-between meals and snacking may be perceived by caregivers as different concepts and vary according to geography, contexts, time of day, food type and location. The findings highlight some agreement with similar studies conducted in the U.S. but also provide new insights into how the consumption of foods and beverages in-between meals may vary between geographic settings. The opportunities for better defining "snacking" within nutrition study design, and how this may inform dietary intake data interpretation, are discussed.

The portion size effect on food intake is robust to contextual size information.

Larger portion sizes have consistently been shown to lead to greater food intake. However, studies of the portion size effect typically provided participants with a single portion of food at a time without any objective information about the size of the portion, and hence failed to consider the potential significance of contextual size information. In order to investigate whether contextual size information moderates the portion size effect, participants were served small or large portions of pasta for lunch in the presence or absence of contextual size information. Study 1 found that the portion size effect on food intake was robust to contextual size information. Study 2 replicated this finding in an online paradigm, showing that contextual size information also had no influence on prospective intake, even when participants chose the portion size they preferred. Both studies also showed that participants' perceptions of how much was appropriate to eat mediated the effect of portion size on intake. A practical implication of our findings is that modifying consumption norms may be an effective way to promote healthier consumer food decisions.

In the eye of the beholder: Visual biases in package and portion size perceptions.

As the sizes of food packages and portions have changed rapidly over the past decades, it has become crucial to understand how consumers perceive and respond to changes in size. Existing evidence suggests that consumers make errors when visually estimating package and portion sizes, and these errors significantly influence subsequent food choices and intake. We outline four visual biases (arising from the underestimation of increasing portion sizes, the dimensionality of the portion size change, labeling effects, and consumer affect) that shape consumers' perceptions of package and portion sizes. We discuss the causes of these biases, review their impact on food consumption decisions, and suggest concrete strategies to reduce them and to promote healthier eating. We conclude with a discussion of important theoretical and practical issues that should be addressed in the future.

Leveraging the happy meal effect: Substituting food with modest nonfood incentives decreases portion size choice.

Despite much effort to decrease food intake by altering portion sizes, "super-sized" meals are the preferred choice of many. This research investigated the extent to which individuals can be subtly incentivized to choose smaller portion sizes. Three randomized experiments (2 in the lab and 1 in the field) established that individuals' choice of full-sized food portions is reduced when they are given the opportunity to choose a half-sized version with a modest nonfood incentive. This substitution effect was robust across different nonfood incentives, foods, populations, and time. Experiment 1 established the effect with children, using inexpensive headphones as nonfood incentives. Experiment 2--a longitudinal study across multiple days--generalized this effect with adults, using the mere chance to win either gift cards or frequent flyer miles as nonfood incentives. Experiment 3 demonstrated the effect among actual restaurant customers who had originally planned to eat a full-sized portion, using the mere chance to win small amounts of money. Our investigation broadens the psychology of food portion choice from perceptual and social factors to motivational determinants.

Small, medium, large or supersize? The development and evaluation of interventions targeted at portion size.

In the past decades, portion sizes of high-caloric foods and drinks have increased and can be considered an important environmental obesogenic factor. This paper describes a research project in which the feasibility and effectiveness of environmental interventions targeted at portion size was evaluated. The studies that we conducted revealed that portion size labeling, offering a larger variety of portion sizes, and proportional pricing (that is, a comparable price per unit regardless of the size) were considered feasible to implement according to both consumers and point-of-purchase representatives. Studies into the effectiveness of these interventions demonstrated that the impact of portion size labeling on the (intended) consumption of soft drinks was, at most, modest. Furthermore, the introduction of smaller portion sizes of hot meals in worksite cafeterias in addition to the existing size stimulated a moderate number of consumers to replace their large meals by a small meal. Elaborating on these findings, we advocate further research into communication and marketing strategies related to portion size interventions; the development of environmental portion size interventions as well as educational interventions that improve people's ability to deal with a 'super-sized' environment; the implementation of regulation with respect to portion size labeling, and the use of nudges to stimulate consumers to select healthier portion sizes.

Improving the design of nutrition labels to promote healthier food choices and reasonable portion sizes.

Accurate and easy-to-understand nutrition labeling is a worthy public health goal that should be considered an important strategy among many to address obesity and poor diet. Updating the Nutrition Facts Panel on packaged foods, developing a uniform front-of-package labeling system and providing consumers with nutrition information on restaurant menus offer important opportunities to educate people about food's nutritional content, increase awareness of reasonable portion sizes and motivate consumers to make healthier choices. The aims of this paper were to identify and discuss: (1) current concerns with nutrition label communication strategies; (2) opportunities to improve the communication of nutrition information via food labels, with a specific focus on serving size information; and (3) important future areas of research on nutrition labeling as a tool to improve diet. We suggest that research on nutrition labeling should focus on ways to improve food labels' ability to capture consumer attention, reduce label complexity and convey numeric nutrition information in simpler and more meaningful ways, such as through interpretive food labels, the addition of simple text, reduced use of percentages and easy-to-understand presentation of serving size information.