Impact of dishware size on energy intake in adult females: A randomized control trial examining effects on within-meal and post-meal energy intake

The influence dishware size has on meal energy intake is unclear and no study to date has examined the impact on total daily energy intake. In a pre-registered RCT we investigate the impact of breakfast dishware size on breakfast and post-breakfast energy intake, as well as daily energy intake and hunger/fullness. In a repeated-measures design, 50 females (aged 18-77 years) were randomised to receive smaller or larger breakfast dishware on two separate days. Energy intake was also measured during the rest of the day. The primary outcomes were breakfast and post-breakfast energy intake (kcal). Secondary outcomes were total daily energy intake (kcal), and hunger/fullness (rated from 0 to 100). We examined if results differed by socioeconomic position (SEP). Dishware did not affect energy intake at breakfast (smaller: M = 394.8 kcal; SD = 172.2 larger: M = 394.4 kcal; SD = 164.4; d = 0.003, p = 0.98), and there was no statistically significant evidence that dishware size affected energy intake after breakfast, though post-breakfast energy intake was somewhat higher after using larger breakfast dishware (smaller: M = 1974.6 kcal; SD = 475.2; larger: M = 2077.5 kcal; SD = 525.9; d = -0.27, p = 0.06). Total daily energy intake, hunger and fullness ratings did not significantly differ between dishware conditions. There was no evidence that SEP moderated the effect of dishware size on energy intake. Smaller vs. larger breakfast dishware size had no significant effect on breakfast or post-breakfast energy intake, hunger, fullness, or daily energy intake. Previous studies may have overestimated the promise of dishware size as an intervention for reducing energy intake. Alternative interventions targeting the food environment should now be prioritised.

Thinking about the bigger picture: Influence of holistic processing on the dishware size effect

Individuals vary in the extent to which they engage in holistic and analytic information processing styles. Holistic processing involves focusing on the interconnectivity and relatedness of items being evaluated, while analytic processing involves focusing on items being judged as discrete elements and independent of context. We examined the contribution of these basic processing styles to the dishware size effect, which proposes that food consumption patterns may be influenced by the size of the dishware (i.e., larger plates increase the amount of food consumed). We observed that participants self-served and consumed more food when using and eating from a larger plate (LP) compared with a smaller plate (SP) (p≤0.01). Importantly, participants who reported greater levels of holistic information processing related to attitudes towards contradictions and attention allocation exhibited smaller variations in portions of food self-served and consumed based on the dishware size used (SP vs. LP). These findings suggest that the susceptibility of individuals to the dishware size effect may be associated with an individual's dispositional tendency to process information in a holistic (vs. analytic) manner.

Size and shape of plates and size of wine glasses and bottles: impact on self-serving of food and alcohol

Background

The physical properties of tableware could influence selection and consumption of food and alcohol. There is considerable uncertainty, however, around the potential effects of different sizes and shapes of tableware on how much food and alcohol people self-serve. These studies aimed to estimate the impact of: 1. Plate size and shape on amount of food self-served; 2.Wine glass and bottle size on amount of wine self-poured.

Methods

140 adults participated in two laboratory studies—each using randomised within-subjects factorial designs—where they self-served food (Study 1) and wine (Study 2):

Study 1: 3 plate sizes (small; medium; large) × 2 plate shapes (circular; square).

Study 2: 3 wine glass sizes (small; medium; large) × 2 wine bottle sizes (75 cl; 50 cl).

Results

Study 1: There was a main effect of plate size: less was self-served on small (76 g less, p < 0.001) and medium (41 g less, p < 0.001) plates, compared to large plates. There was no evidence for a main effect of plate shape (p = 0.46) or a size and shape interaction (p = 0.47).

Study 2: There was a main effect of glass size: less was self-served in small (34 ml less, p < 0.001) and medium (17 ml less, p < 0.001) glasses, compared to large glasses. There was no evidence of a main effect of bottle size (p = 0.20) or a glass and bottle size interaction (p = 0.18).

Conclusions

Smaller tableware (i.e. plates and wine glasses) decreases the amount of food and wine self-served in an initial serving. Future studies are required to generate estimates on selection and consumption in real world settings when numerous servings are possible.

Protocol registration information: OSF (https://osf.io/dj3c6/) and ISRCTN (10.1186/ISRCTN66774780).

Supplementary Information

The online version contains supplementary material available at 10.1186/s40359-021-00645-z.

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.

Efficiency of In-Store Interventions to Impact Customers to Purchase Healthier Food and Beverage Products in Real-Life Grocery Stores: A Systematic Review and Meta-Analysis

Grocery stores are important settings to promote healthier food and beverage choices. The present paper aims at reviewing the effectiveness of different types of in-store interventions and how they impact sales of different product category in real grocery stores. Systematic search was conducted in six databases. In-store interventions were categorized according to the framework by Kraak et al. (2017) into one or more of eight interventions (e.g., place, profile, portion, pricing, promotion, healthy default picks, prompting and proximity). This systematic theme-based review follows the preferred reporting items for systematic reviews and meta-analyses (PRISMA) data screening and selection. Thirty-six studies were included in the qualitative synthesis and 30 studies were included in the meta-analysis, representing 72 combinations of in-store interventions. The analysis demonstrates that interventions overall had small significant effect size (ES) using Cohen's d on food purchase behavior (d = 0.17, 95% CI [0.04, 0.09]), with largest ES for pricing (d = 0.21) and targeting fruits and vegetables (d = 0.28). Analysis of ES of in-store interventions show that pricing, and pricing combined with promotion and prompting, effectively impacted purchase behavior. Interventions significantly impacted both sales of healthy and unhealthy products and significantly increased sales of fruits and vegetables, healthy beverage and total volume of healthy products. Results should however be interpreted with some caution, given the relatively low quality of overall evidence and low number of studies and observations for some types of intervention. Further research exploring impact on different in-store interventions and targeting especially unhealthy products are needed.

Out of the lab and into the wild: The influence of portion size on food intake in laboratory vs. real-world settings

External influences on eating behaviour, such as portion size, have been reliably shown to influence food intake in the laboratory. However, little research has examined whether laboratory settings under or overestimate the effect that external influences have on food intake compared to when studied in the real-world. In Study 1, 60 participants (mean age = 32 years) were randomized to consume a large (200 g) or small (100 g) portion of popcorn under controlled laboratory conditions and during a separate session in their home. Results showed that the effect of portion size on food intake was larger at home (d = 0.97) than in the laboratory (d = 0.56). Furthermore, participants reported feeling more relaxed eating at home compared to the laboratory. In Study 2, we examined whether comparable results were observed in a semi-naturalistic laboratory designed to resemble a home setting. 59 participants (mean age = 28 years) completed the same procedure as Study 1 in a standard and a semi-naturalistic laboratory setting. Although participants reported having higher levels of private self-awareness in the standard laboratory, the effect that portion size had on food intake did not differ between the standard laboratory (d = 0.50) and the semi-naturalistic laboratory (d = 0.49). The impact that external influences on eating, such as portion size, have on food intake in the real-world may be underestimated when studied under laboratory conditions.

Unpalatable food for thought: Let marketing research guide effective public obesity interventions

The prevalence of obesity is growing unabatedly despite the considerable efforts directed at the problem. Although abundant research has contributed to our understanding of the multifactorial causes of obesity, there is less attention to research that is relevant for guiding social marketers, public health professionals and policymakers in delivering public health interventions for countering and/or preventing the problem of obesity. This review offers six points for identifying and developing research relevant for guiding community-wide obesity interventions based on the idea that an applied marketing research perspective offers a better model for identifying effective interventions than more theoretical academic research. Specifically, the research guiding public health and social marketing interventions needs to (1) provide information on ultimate outcomes (weight, health and unintended consequences) more than intermediate outcomes (beliefs, attitudes and behaviour), (2) report on observations collected over the longer term, (3) use natural settings (even at a cost of internal validity), (4) endeavour to overcome observer-effects, (5) report effect sizes (rather than statistical significance) and (6) use moderator analyses to capture variation in how a population responds to interventions.

Behavior Change

Despite rapid growth in the empirical research on behavior change, modern science has yet to produce a coherent set of recommendations for individuals and organizations eager to align everyday actions with enduringly valued goals. We propose the process model of behavior change as a parsimonious framework for organizing strategies according to where they have their primary impact in the generation of behavioral impulses. To begin, individuals exist in objective situations, only certain features of which attract attention, which in turn lead to subjective appraisals, then finally give rise to response tendencies. Unhealthy habits develop when conflicting impulses are consistently resolved in favor of momentary temptations instead of valued goals. To change behavior for the better, we can strategically modify objective situations, where we pay attention, how we construct appraisals, and how we enact responses. Crucially, behavior change strategies can be initiated either by the individual (i.e., self-control) or by others (e.g., a benevolent employer).

Self-nudging and the citizen choice architect

This article argues that nudges can often be turned into self-nudges: empowering interventions that enable people to design and structure their own decision environments – that is, to act as citizen choice architects. Self-nudging applies insights from behavioral science in a way that is practicable and cost-effective, but that sidesteps concerns about paternalism or manipulation. It has the potential to expand the scope of application of behavioral insights from the public to the personal sphere (e.g., homes, offices, families). It is a tool for reducing failures of self-control and enhancing personal autonomy; specifically, self-nudging can mean designing one's proximate choice architecture to alleviate the effects of self-control problems, engaging in education to understand the nature and causes of self-control problems and employing simple educational nudges to improve goal attainment in various domains. It can even mean self-paternalistic interventions such as winnowing down one's choice set by, for instance, removing options. Policy-makers could promote self-nudging by sharing knowledge about nudges and how they work. The ultimate goal of the self-nudging approach is to enable citizen choice architects’ efficient self-governance, where reasonable, and the self-determined arbitration of conflicts between their mutually exclusive goals and preferences.

Cognitive and environmental interventions to encourage healthy eating: evidence-based recommendations for public health policy

Policymakers are focused on reducing the public health burden of obesity. The UK average percentage of adults classified as obese is 26%, which is double that of the global average. Over a third of UK adults report using at least one weight management aid. Yet, many people still struggle to change their diet-related behaviour, despite having the awareness, intention and capability to do so. This 'intention-behaviour gap' may be because most existing dietary-choice interventions focus on individual decision-making, ignoring the effects of environmental cues on human behaviour. Behaviour change interventions that 'nudge' people into making healthier choices by modifying the food environment have been shown to be effective. However, this type of intervention is typically challenging for policymakers to implement for economic, ethical and public accessibility reasons. To overcome these concerns, policymakers should consider 'boosting' interventions. Boosting involves enhancing competences that help people make decisions consistent with their goals. Here, we outline cognitive training as a boosting intervention to tackle obesity. We synthesize the evidence for one type of cognitive training (go/no-go training) that may be effective at modifying food-related decisions and reducing body weight. We offer evidence-based recommendations for an obesity-focused Public Health Wales behaviour change programme.

A review of evidence supporting current strategies, challenges, and opportunities to reduce portion sizes

Although there is considerable evidence for the portion-size effect and its potential impact on health, much of this has not been successfully applied to help consumers reduce portion sizes. The objective of this review is to provide an update on the strength of evidence supporting strategies with potential to reduce portion sizes across individuals and eating contexts. Three levels of action are considered: food-level strategies (targeting commercial snack and meal portion sizes, packaging, food labels, tableware, and food sensory properties), individual-level strategies (targeting eating rate and bite size, portion norms, plate-cleaning tendencies, and cognitive processes), and population approaches (targeting the physical, social, and economic environment and health policy). Food- and individual-level strategies are associated with small to moderate effects; however, in isolation, none seem to have sufficient impact on food intake to reverse the portion-size effect and its consequences. Wider changes to the portion-size environment will be necessary to support individual- and food-level strategies leading to portion control.

Plate size and food consumption: a pre-registered experimental study in a general population sample

BACKGROUND

There is considerable uncertainty regarding the impact of tableware size on food consumption. Most existing studies have used small and unrepresentative samples and have not followed recommended procedures for randomised controlled trials, leading to increased risk of bias. In the first pre-registered study to date, we examined the impact on consumption of using larger versus smaller plates for self-served food. We also assessed impact on the underlying meal micro-structure, such as number of servings and eating rate, which has not previously been studied.

METHODS

The setting was a purpose-built naturalistic eating behaviour laboratory. A general population sample of 134 adult participants (aged 18-61 years) was randomly allocated to one of two groups varying in the size of plate used for self-serving lunch: large or small. The primary outcome was amount of food energy (kcal) consumed during a meal. Additionally, we assessed impact on meal micro-structure, and examined potential modifying effects of executive function, socio-economic position, and sensitivity to perceptual cues.

RESULTS

There was no clear evidence of a difference in consumption between the two groups: Cohen's d = 0.07 (95% CI [- 0.27, 0.41]), with participants in the large plate group consuming on average 19.2 (95% CI [- 76.5, 115.0]) more calories (3%) compared to the small plate group (large: mean (SD) = 644.1 (265.0) kcal, versus small: 624.9 (292.3) kcal). The difference between the groups was not modified by individual characteristics. There was no evidence of impact on meal micro-structure, with the exception of more food being left on the plate when larger plates were used.

CONCLUSIONS

This study suggests that previous meta-analyses of a low-quality body of evidence may have considerably overestimated the effects of plate size on consumption. However, the possibility of a clinically significant effect - in either direction - cannot be excluded. Well-conducted trials of tableware size in real-world field settings are now needed to determine whether changing the size of tableware has potential to contribute to efforts to reduce consumption at population-level.

TRIAL REGISTRATION

The study protocol ( https://osf.io/e3dfh/ ) and data analysis plan ( https://osf.io/sh5u7/ ) were pre-registered on the Open Science Framework.

Smaller dishware to reduce energy intake: fact or fiction?

The potential effects of dishware size on energy intake are unclear, as many previous studies have been of low methodological quality. A newly published paper by Kosīte et al. (IJBNPA 10.1186/s12966-019-0826-1, 2019) reports findings from a rigorous, pre-registered investigation of the effects of manipulating plate size on total energy intake within a single eating occasion. This Editorial considers the implications of these new findings in light of previous evidence pertaining to the efficacy of behavioral nudges in particular, and in relation to contextual drivers of food consumption more generally. We conclude that the potential impact of behavioral nudges may have been exaggerated in the past, and call for future high-quality randomized controlled trials to establish whether reducing dishware size and other behavioral nudges might offer an effective complement to more comprehensive, multi-level interventions to reduce overconsumption of foods and beverages at a population-level.

Exploring the Experiences of People with Obesity Using Portion Control Tools-A Qualitative Study

Large portion sizes increase consumption and eating smaller portions is recommended as a weight control strategy. However, many people report difficulties enacting this advice. This study examined the experience of individuals using two commercially available portion-control tools to try to manage their weight. In a crossover design, 29 adults with obesity (18 women) who had attended a previous weight loss intervention in the community were invited to use two portion-control tool sets over a period of four weeks (two weeks each) and to complete a semi-structured questionnaire about their experience. The tools were a guided crockery set (sector plate, calibrated bowl, and calibrated glass) and a set of calibrated serving spoons (one for starch, one for protein, and one for vegetables). Data were analyzed using thematic framework analysis. A key theme was related to the educational benefits of the tools, such as generating awareness, guidance, and gaining an independent ability to judge appropriate portions. Other key themes were tool usability, acceptability, and feasibility of usage. Barriers identified by participants included unclear markings/instructions and the inconvenience of using the tool when eating away from home. Overall, the tools were perceived to be educationally useful, easy to use, and potentially effective for learning to control portions, which suggested that these instruments could help in weight management interventions alongside other strategies. Elements of the tool design could influence the ability of participants to adhere to using the tool, and hence allow the educational effect to be mediated.

Beyond Willpower: Strategies for Reducing Failures of Self-Control

Almost everyone struggles to act in their individual and collective best interests, particularly when doing so requires forgoing a more immediately enjoyable alternative. Other than exhorting decision makers to "do the right thing," what can policymakers do to reduce overeating, undersaving, procrastination, and other self-defeating behaviors that feel good now but generate larger delayed costs? In this review, we synthesize contemporary research on approaches to reducing failures of self-control. We distinguish between self-deployed and other-deployed strategies and, in addition, between situational and cognitive intervention targets. Collectively, the evidence from both psychological science and economics recommends psychologically informed policies for reducing failures of self-control.

Effects of a portion design plate on food group guideline adherence among hospital staff

Food group guideline adherence is vital to prevent obesity and diabetes. Various studies have demonstrated that environmental variables influence food intake behaviour. In the present study we examined the effect of a portion design plate with food group portion guidelines demarcated by coloured lines (ETE Plate™). A two-group quasi-experimental design was used to measure proportions of carbohydrate, vegetable and protein portions and user experience in a hospital staff lounge setting in Singapore. Lunch was served on the portion design plate before 12.15 hours. For comparison, a normal plate (without markings) was used after 12.15 hours. Changes in proportions of food groups from 2 months before the introduction of the design plate were analysed in a stratified sample at baseline (859 subjects, all on normal plates) to 1, 3 and 6 months after (in all 1016 subjects on the design plate, 968 subjects on the control plate). A total of 151 participants were asked about their experiences and opinions. Between-group comparisons were performed using t tests. Among those served on the portion design plate at 6 months after its introduction, the proportion of vegetables was 4·71 % (P < 0·001) higher and that of carbohydrates 2·83 % (P < 0·001) lower relative to the baseline. No significant change was found for proteins (−1·85 %). Over 6 months, we observed different change patterns between the different food group proportions. While participants were positive about the portion design plate, they did not think it would influence their personal behaviour. A portion design plate might stimulate food group guideline adherence among hospital staff and beyond.

Controlled testing of novel portion control plate produces smaller self-selected portion sizes compared to regular dinner plate

Background

Obesity is a global health crisis, and portion control is a key method for reducing excess body weight. Given consumers’ familiarity with large portion sizes, reducing portion sizes can be difficult. Smaller plates are often recommended to reduce portion sizes and appear to reduce portion sizes. However, there are no studies evaluating dishes specifically designed to facilitate portion control. The aim of the present study was to validate the efficacy of a novel portion control plate inspired by the Ebbinghaus and Delboeuf visual illusions to promote serving smaller portions compared to a larger dinner plate.

Methods

In two studies with a total of 110 university students, we determined whether the use of the portion control plate would result in smaller food portions compared to a larger dinner plate. The portion control plate was smaller and incorporated portion size indicators. Study 1 used instructions from My Plate based on plate ratios (e.g., “the USDA recommends filling half your plate with vegetables”) and study 2 used absolute portion size recommendations (e.g., “1 cup of vegetables”).

Results

The portion control plate produced smaller self-selected servings in both studies. However, the servings of vegetables selected were smaller than recommended portion sizes for both the portion control plate and the regular dinner plate.

Conclusions

Portion control plates have the potential to reduce self-selected portion sizes. Future research should include studies in a broader range of ages and clinical trials of portion control dishes for weight loss.

Electronic supplementary material

The online version of this article (doi:10.1186/s40608-017-0167-z) contains supplementary material, which is available to authorized users.

How does plate size affect estimated satiation and intake for individuals in normal-weight and overweight groups?

OBJECTIVE

Manipulating plate sizes could possibly introduce perceptual biases for judging food satiation and intake, which is thought to be related to the Delbeouf illusion - a visual illusion based on the perceived size of one object related to another. This study was to investigate whether an association exists between an individual's susceptibility to the plate-size-effect and their weight status (i.e. normal-weight versus overweight).

METHODS

The study assessed the effect of plate size amongst normal-weight (N = 124) and overweight (N = 79) New Zealand Europeans. All participants were asked to rate estimated satiation (ES) and intake (EI) on Visual Analogue Scales for 20 food images, which comprised photographs of ten different dishes placed on large versus small plates. These responses were analysed by mixed-model ANCOVA.

RESULTS

The results showed that the plate size had significant effects on ES (F_{(1, 1986)} = 19.14, p < 0.001) and EI (F_(1,1986) = 5.25; p = 0.048), with the small plate associated with higher ES and lower EI than the large plate. Significant differences in ES and EI were also evident across the weight groups (ES: F_(1,1986) = 4.26, p = 0.039; EI: F_(1,1986) = 42.22, p < 0.001), with the normal-weight group reported higher ES and lower EI than the overweight group. Furthermore, the weight group and the plate-size-effect were found to be involved in a significant interaction for EI. Post-hoc tests showed that the plate size only had a significant effect for the normal-weight group (p < 0.05), but not for the overweight group.

CONCLUSIONS

Overall, the study demonstrated that the normal-weight and overweight group differed in their susceptibilities to the plate-size-effect (reflected by EI). This study revealed some potential moderators for the plate-size-effect, such as the type of dish, and its associated appeal and familiarity, and provided useful indications about the effectiveness of small plates for food reduction.