Will smaller plates lead to smaller waists? A systematic review and meta-analysis of the effect that experimental manipulation of dishware size has on energy consumption

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.

Acute and two-week effects of neotame, stevia rebaudioside M and sucrose-sweetened biscuits on postprandial appetite and endocrine response in adults with overweight/obesity-a randomised crossover trial from the SWEET consortium

BACKGROUND

Sweeteners and sweetness enhancers (S&SE) are used to replace energy yielding sugars and maintain sweet taste in a wide range of products, but controversy exists about their effects on appetite and endocrine responses in reduced or no added sugar solid foods. The aim of the current study was to evaluate the acute (1 day) and repeated (two-week daily) ingestive effects of 2 S&SE vs. sucrose formulations of biscuit with fruit filling on appetite and endocrine responses in adults with overweight and obesity.

METHODS

In a randomised crossover trial, 53 healthy adults (33 female, 20 male) with overweight/obesity in England and France consumed biscuits with fruit filling containing 1) sucrose, or reformulated with either 2) Stevia Rebaudioside M (StRebM) or 3) Neotame daily during three, two-week intervention periods with a two-week washout. The primary outcome was composite appetite score defined as [desire to eat + hunger + (100 - fullness) + prospective consumption]/4.

FINDINGS

Each formulation elicited a similar reduction in appetite sensations (3-h postprandial net iAUC). Postprandial insulin (2-h iAUC) was lower after Neotame (95% CI (0.093, 0.166); p < 0.001; d = -0.71) and StRebM (95% CI (0.133, 0.205); p < 0.001; d = -1.01) compared to sucrose, and glucose was lower after StRebM (95% CI (0.023, 0.171); p < 0.05; d = -0.39) but not after Neotame (95% CI (-0.007, 0.145); p = 0.074; d = -0.25) compared to sucrose. There were no differences between S&SE or sucrose formulations on ghrelin, glucagon-like peptide 1 or pancreatic polypeptide iAUCs. No clinically meaningful differences between acute vs. two-weeks of daily consumption were found.

INTERPRETATION

In conclusion, biscuits reformulated to replace sugar using StRebM or Neotame showed no differences in appetite or endocrine responses, acutely or after a two-week exposure, but can reduce postprandial insulin and glucose response in adults with overweight or obesity.

FUNDING

The present study was funded by the Horizon 2020 program: Sweeteners and sweetness enhancers: Impact on health, obesity, safety and sustainability (acronym: SWEET, grant no: 774293).

Food portion sizes: trends and drivers in an obesogenic environment

The prevalence of overweight and obesity in children and adults has increased worldwide. A strong environmental factor contributing to the obesity epidemic is food portion size (PS). This review evaluates the current evidence linking food PS to obesity, examines the effects of PS on energy intake (EI), and discusses the drivers of food PS selection. The leading causes of the rise in PS include globalisation, intensive farming methods, the impact of World War II, due to shortage of staple foods, and the notion of 'waste not, want not'. Large PS of energy-dense foods may stimulate overconsumption, leading to high EI levels. However, the studies have not shown a cause-and-effect relationship, due to confounding factors. Important mechanisms explaining the attractiveness of larger PS leading to higher EI levels are value for money, portion distortion, labels on food packaging, and tableware. Consumers depend on external rather than internal PS cues to guide consumption, irrespective of satiety levels. Further research is recommended on food consumption patterns to inform policymakers and provide information and insights about changes in diet.

Weighing heavy: Heavy serving dishes increase food serving

The current work demonstrates that people serve themselves greater amounts of food when carrying heavier serving dishes. This effect occurs because increases in carried weight lower consumers' sensitivity to the weight of the food served. Decreased sensitivity to weight of food served in turn leads people to continue serving past the point where they would normally stop. The paper demonstrates this effect across two lab studies involving actual food serving (with a third lab study extending the outcomes to unhealthy food choices reported in the S1 Appendix). The studies also demonstrate liking for the food moderates the effect, such that carrying greater weight leads people to serve an increased amount of liked, but not of less well liked, foods. The findings extend prior research regarding the effects of dish weight on food judgment to provide a first demonstration of effects of weight not only on judgment but on behavior. In this, they help expand our understanding of the ways in which elements in the eating environment effects food consumption. In addition, the studies provide initial evidence for the mechanism behind the phenomenon: reduced sensitivity to weight. The research carries important implications for public well being, given that increases in serving sizes may contribute to obesity.

Impact of acute consumption of beverages containing plant-based or alternative sweetener blends on postprandial appetite, food intake, metabolism, and gastro-intestinal symptoms: Results of the SWEET beverages trial

Project SWEET examined the barriers and facilitators to the use of non-nutritive sweeteners and sweetness enhancers (hereafter "S&SE") alongside potential risks/benefits for health and sustainability. The Beverages trial was a double-blind multi-centre, randomised crossover trial within SWEET evaluating the acute impact of three S&SE blends (plant-based and alternatives) vs. a sucrose control on glycaemic response, food intake, appetite sensations and safety after a carbohydrate-rich breakfast meal. The blends were: mogroside V and stevia RebM; stevia RebA and thaumatin; and sucralose and acesulfame-potassium (ace-K). At each 4 h visit, 60 healthy volunteers (53% male; all with overweight/obesity) consumed a 330 mL beverage with either an S&SE blend (0 kJ) or 8% sucrose (26 g, 442 kJ), shortly followed by a standardised breakfast (∼2600 or 1800 kJ with 77 or 51 g carbohydrates, depending on sex). All blends reduced the 2-h incremental area-under-the-curve (iAUC) for blood insulin (p < 0.001 in mixed-effects models), while the stevia RebA and sucralose blends reduced the glucose iAUC (p < 0.05) compared with sucrose. Post-prandial levels of triglycerides plus hepatic transaminases did not differ across conditions (p > 0.05 for all). Compared with sucrose, there was a 3% increase in LDL-cholesterol after stevia RebA-thaumatin (p < 0.001 in adjusted models); and a 2% decrease in HDL-cholesterol after sucralose-ace-K (p < 0.01). There was an impact of blend on fullness and desire to eat ratings (both p < 0.05) and sucralose-acesulfame K induced higher prospective intake vs sucrose (p < 0.001 in adjusted models), but changes were of a small magnitude and did not translate into energy intake differences over the next 24 h. Gastro-intestinal symptoms for all beverages were mostly mild. In general, responses to a carbohydrate-rich meal following consumption of S&SE blends with stevia or sucralose were similar to sucrose.

Portion-control tableware differentially impacts eating behaviour in women with and without overweight

Portion control tableware has been described as a potentially effective approach for weight management, however the mechanisms by which these tools work remain unknown. We explored the processes by which a portion control (calibrated) plate with visual stimuli for starch, protein and vegetable amounts modulates food intake, satiety and meal eating behaviour. Sixty-five women (34 with overweight/obesity) participated in a counterbalanced cross-over trial in the laboratory, where they self-served and ate a hot meal including rice, meatballs and vegetables, once with a calibrated plate and once with a conventional (control) plate. A sub-sample of 31 women provided blood samples to measure the cephalic phase response to the meal. Effects of plate type were tested through linear mixed-effect models. Meal portion sizes (mean ± SD) were smaller for the calibrated compared with the control plate (served: 296 ± 69 vs 317 ± 78 g; consumed: 287 ± 71 vs 309 ± 79 g respectively), especially consumed rice (69 ± 24 vs 88 ± 30 g) (p < 0.05 for all comparisons). The calibrated plate significantly reduced bite size (3.4 ± 1.0 vs 3.7 ± 1.0 g; p < 0.01) in all women and eating rate (32.9 ± 9.5 vs 33.7 ± 9.2 g/min; p < 0.05), in lean women. Despite this, some women compensated for the reduced intake over the 8 h following the meal. Pancreatic polypeptide and ghrelin levels increased post-prandially with the calibrated plate but changes were not robust. Plate type had no influence on insulin, glucose levels, or memory for portion size. Meal size was reduced by a portion-control plate with visual stimuli for appropriate amounts of starch, protein and vegetables, potentially because of the reduced self-served portion size and the resulting reduced bite size. Sustained effects may require the continued use of the plate for long-term impact.

Diet Therapy Using a Small Rice Bowl among Japanese Men with Diabetes: A Randomized Controlled Trial

Background

This study aimed to investigate the effectiveness at 1 and 3 months of using a smaller rice bowl for diet therapy among Japanese men with type 2 diabetes.

Methods

A parallel-group randomized controlled trial was conducted at a medical clinic in Japan. The participants were men with type 2 diabetes mellitus, aged 20-80 years, with glycosylated hemoglobin <8.5%, and who ate rice one or more times per day at home. The intervention group (36 men) received a small rice bowl from which to eat the usual diet therapy, and the control group (38 men) received only the usual diet therapy.

Results

The changes in weight and body mass index among the intervention group at 1 month were significantly higher than those in the control group. There were no significant differences between the two groups at 3 months.

Conclusion

The effects of using a small rice bowl were minor and short-term.

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.

Guppies (Poecilia reticulata) are deceived by visual illusions during obstacle negotiation

Animals travelling in their natural environment repeatedly encounter obstacles that they can either detour or go through. Gap negotiation requires an accurate estimation of the opening's size to avoid getting stuck or being injured. Research on visual illusions has revealed that in some circumstances, transformation rules used to generate a three-dimensional representation from bidimensional retinal images fail, leading to systematic errors in perception. In Ebbinghaus and Delboeuf illusions, the presence of task-irrelevant elements causes us to misjudge an object's size. Susceptibility to these illusions was observed in other animals, although with large intraspecific differences. In this study, we investigated whether fish can accurately estimate gap size and whether during this process they may be deceived by illusory patterns. Guppies were extremely accurate in gap negotiation, discriminating holes with a 10% diameter difference. When presented with two identical holes surrounded by inducers to produce Ebbinghaus and Delboeuf patterns, guppies misperceived gap size in the predicted direction. So far, researchers have principally considered illusions as useful tools for exploring the cognitive processing underlying vision. Our findings highlight the possibility that they have important ecological implications, affecting the everyday interactions of an animal with its physical world besides its intra- and interspecific relationships.

Where and when are portion sizes larger in young children? An analysis of eating occasion size among 1·5-5-year-olds in the UK National Diet and Nutrition Survey (2008-2017)

OBJECTIVE

To identify eating occasion-level and individual-level factors associated with the consumption of larger portions in young children and estimate their relative importance.

DESIGN

Cross-sectional.

SETTING

Data from parent-reported 4-d food diaries in the UK National Diet and Nutrition Survey (2008-2017) were analysed. Multilevel models explored variation in eating occasion size (kJ) within (n 48 419 occasions) and between children (n 1962) for all eating occasions. Eating contexts: location, eating companion, watching TV, and sitting at a table and individual characteristics: age, gender, ethnicity and parental socio-economic status were explored as potential correlates of eating occasion size.

PARTICIPANTS

Children aged 1·5-5 years.

RESULTS

Median eating occasion size was 657 kJ (IQR 356, 1117). Eating occasion size variation was primarily attributed (90 %) to differences between eating occasions. Most (73 %) eating occasions were consumed at home. In adjusted models, eating occasions in eateries were 377 kJ larger than at home. Eating occasions sitting at a table, v. not, were 197 kJ larger. Eating in childcare, with additional family members and friends, and whilst watching TV were other eating contexts associated with slightly larger eating occasion sizes.

CONCLUSIONS

Eating contexts that vary from one eating occasion to another are more important than demographic characteristics that vary between children in explaining variation in consumed portion sizes in young children. Strategies to promote consumption of age-appropriate portion sizes in young children should be developed, especially in the home environment, in eating contexts such as sitting at the table, eating with others and watching TV.

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.

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.

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.

Negative energy balance during military training: The role of contextual limitations

During multiday training exercises, soldiers almost systematically face a moderate-to-large energy deficit, affecting their body mass and composition and potentially their physical and cognitive performance. Such energy deficits are explained by their inability to increase their energy intake during these highly demanding periods. With the exception of certain scenarios in which rations are voluntarily undersized to maximize the constraints, the energy content of the rations are often sufficient to maintain a neutral energy balance, suggesting that other limitations are responsible for such voluntary and/or spontaneous underconsumption. In this review, the overall aim was to present an overview of the impact of military training on energy balance, a context that stands out by its summation of specific limitations that interfere with energy intake. We first explore the impact of military training on the various components of energy balance (intake and expenditure) and body mass loss. Then, the role of the dimensioning of the rations (total energy content above or below energy expenditure) on energy deficits are addressed. Finally, the potential limitations inherent to military training (training characteristics, food characteristics, timing and context of eating, and the soldiers' attitude) are discussed to identify potential strategies to spontaneously increase energy intake and thus limit the energy deficit.

Does food deprivation affect perceived size?

Exposure to food-related stimuli could lead to the triggering of a set of biological, emotional and cognitive responses. Such responses can be pronounced following food deprivation. Indeed, previous research showed that even a moderate period of food deprivation is sufficient to increase perceptual precision to detect changes along food size and to change the processing style of food-related stimuli. It is unclear, however, whether food deprivation also leads to systematic biases along the perception of food size. Here, we used two classic psychophysical methods, the method of constant stimuli and the method of adjustment, adapted to the field of food perception, to study the effect of food deprivation on average perceived food size. In two experiments, food deprived and non-deprived participants were asked to compare a series of food and non-food visual stimuli along their size. The results were inconsistent and depended upon the method used. When found, small bias effects resulted in food stimuli perceived as bigger following food deprivation. The results show that unlike the reliable effects motivational factors have on perceptual precision and on perceptual processing style, they have an inconsistent influence on average perceived food size.

Do Adults Draw Differently-Sized Meals on Larger or Smaller Plates? Examining Plate Size in a Community Sample

Background

Prior research has reported that plate size may influence an individual's perceptions and recall of food and meal size. Therefore, manipulating plate size could influence projected meal quantities and portion size among community dwelling adults.

Methods

The present study interviewed 281 adult parents in their own homes in a medium-sized city in the United States. Participants were asked to accurately draw and label the foods they expected to eat for dinner that night, drawing on either a 23 cm or 28 cm paper plate. The respondents were then asked to label each food drawn in order to ensure proper recording of meals.

Results

Results showed clear differences in drawn food sizes between plate sizes as well as between sexes. Larger plates had about 24% more food drawn on them than small plates. Men drew their meals on 28 cm plates to be 37% larger than men who received 23 cm plates, while women with 28 cm plates drew their meals to be about 17% larger than women given 23 cm plates. Most (60%) of the overall differences in food size between plates came from the biggest food that was drawn. Women and men both drew bigger meat portions on 28 cm plates when compared to the meat portions on 23 cm plates.

Conclusions

Overall, these findings support the concept that adult participants' estimates of dinner meal size may be shaped by plate size. The effect of differing plate sizes appears to be more powerful for men than women, and may encourage greater food consumption among men, primarily as meat products.

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.

Child and adult snack food intake in response to manipulated pre-packaged snack item quantity/variety and snack box size: a population-based randomized trial

OBJECTIVES

Snacks contribute to overconsumption of energy-dense foods and thence obesity. Previous studies in this area are limited by self-reported data and small samples. In a large population-based cohort of parent-child dyads, we investigated how modification of pre-packaged snack food, i.e. (a) item quantity and variety, and (b) dishware (boxed container) size affected intake.

METHODS

Design: Randomized trial nested within the cross-sectional Child Health CheckPoint of the Longitudinal Study of Australian Children, clustered by day of visit.

SAMPLE

1299 11-12 year olds, 1274 parents.

EXPOSURE

2 × 2 manipulation of snack box container size and item quantity/variety: (1) small box, few items, (2) large box, few items, (3) small box, more items, (4) large box, more items.

PROCEDURE

Participants received a snack box during a 15 min break within their 3.5 h visit; any snacks remaining were weighed.

OUTCOMES

Consumed quantity (grams) and energy intake (kilojoules).

ANALYSES

Unadjusted linear regression.

RESULTS

Children who were offered a greater quantity and variety of snack items consumed considerably more energy and a slightly higher food mass (main effect for energy intake: 349 kJ, 95% CI 282-416, standardized mean difference (effect size) 0.66; main effect for mass: 10 g, 95% CI 3-17, effect size 0.17). In contrast, manipulating box size had little effect on child consumption, and neither box size nor quantity/variety of items consistently affected adults' consumption.

CONCLUSION

In children, reducing the number and variety of snack food items available may be a more fruitful intervention than focusing on container or dishware size. Effects observed among adults were small, although we could not exclude social desirability bias in adults aware of observation.

Preschoolers exhibit conformity to computer-simulated food portion selection behaviors of remote peers

Children have been found to rely on others for food choice and food intake cues, but it is unclear whether a similar type of social modeling occurs for food portion selection, especially among young children. Given that portion size predicts energy intake, it is important to understand the role of social influence on portion selection behavior early in life. The present study aimed to determine preschoolers' conformity to food portion selection patterns of remote peers using a computerized Portion Selection Task and examined the role of parents' feeding styles in children's susceptibility to others' food portion choices. Seventy-five 3-6 year old Singaporean children (M = 62 ± 0.72 months) were asked to make food portion selections of high-energy-density (ED) foods and low-ED foods both independently and after having viewed remote peers' portion selections of the same foods. In the unhealthy peers condition, children saw peers choose large portions of high-ED foods and small portions of low-ED foods, while in the healthy peers condition, children saw peers select large portions of low-ED foods and small portions of high-ED foods. Parents were surveyed about their child feeding practices. Results revealed that participants exhibited conformity to the portion sizes of remote peers for both high-ED and low-ED foods under the healthy peers condition, but only marginally for high-ED foods under the unhealthy peers condition. Parents' higher restriction of foods for child's health was marginally associated with lower conformity to peers' portion selections of unhealthy foods and higher conformity to peers' portion selections of healthy foods. This study provides support for social modeling of food portion selection among young children, but the extent of social modeling may be contingent on characteristics of the food.

The rewarding effects of number and surface area of food in rats

Visual cues have an important role in food preference for both rats and humans. Here, we aim to isolate the effects of numerosity, density, and surface area on food preference and running speed in rats, by using a forced-choice maze paradigm. In Experiment 1, rats preferred and ran faster for a group of multiple smaller pellets rather than a single large pellet, corroborating previous research (Capaldi, Miller, & Alptekin Journal of Experimental Psychology: Animal Behavior Processes, 15(1), 75-80, 1989). Further experiments tested the prevailing hypothesis that multiple food pieces are more reinforcing because they occupy a larger surface area. Experiment 2 controlled for numerosity by utilizing a continuous food: mashed potatoes flattened to cover a larger surface area or rounded into a ball. The rats preferred and ran faster for the flattened potatoes, suggesting surface area plays a role in quantity estimations. Finally, in Experiment 3, rats displayed no preference or difference in running speed between a group of scattered and clustered pellets when number of pellets were kept constant. Taken together, these results suggest that density has an important role in food perception-that is, the rewarding effect of higher numerosity or larger surface area is removed when the food does not fill out the entire space. Alternative explanations and implications for human diet are discussed.

Eating with a smaller spoon decreases bite size, eating rate and ad libitum food intake in healthy young males

There is a paucity of data examining the effect of cutlery size on the microstructure of within-meal eating behaviour or food intake. Therefore, the present studies examined how manipulation of spoon size influenced these eating behaviour measures in lean young men. In study one, subjects ate a semi-solid porridge breakfast ad libitum, until satiation. In study two, subjects ate a standardised amount of porridge, with mean bite size and mean eating rate covertly measured by observation through a one-way mirror. Both studies involved subjects completing a familiarisation visit and two experimental visits, where they ate with a teaspoon (SMALL) or dessert spoon (LARGE), in randomised order. Subjective appetite measures (hunger, fullness, desire to eat and satisfaction) were made before and after meals. In study one, subjects ate 8 % less food when they ate with the SMALL spoon (SMALL 532 (SD 189) g; LARGE 575 (SD 227) g; P=0·006). In study two, mean bite size (SMALL 10·5 (SD 1·3) g; LARGE 13·7 (SD 2·6) g; P<0·001) and eating rate (SMALL 92 (SD 25) g/min; LARGE 108 (SD 29) g/min; P<0·001) were reduced in the SMALL condition. There were no condition or interaction effects for subjective appetite measures. These results suggest that eating with a small spoon decreases ad libitum food intake, possibly via a cascade of effects on within-meal eating microstructure. A small spoon might be a practical strategy for decreasing bite size and eating rate, likely increasing oral processing, and subsequently decreasing food intake, at least in lean young men.

The effects of bowl size and portion size on food intake and fullness ratings in a sample of Japanese men

OBJECTIVE

Portion sizes and bowl sizes may be related to food intake and perceived fullness. The objective of the present study was to investigate the effects of portion size and bowl size and possible interactions between these variables on food intake and fullness in a sample of Japanese men.

DESIGN

Participants ate four different experimental meals across four weeks and completed questionnaires about their fullness using a visual analogue scale administered before and after meals. The four meal patterns included consistent portions of several foods commonly eaten together in typical Japanese meals, along with 150 g of rice served in a small rice bowl (diameter of 11·5 cm), 150 g of rice served in a large rice bowl (diameter of 13·5 cm), 250 g of rice served in a small rice bowl or 250 g of rice served in a large rice bowl.

SETTING

Tokyo.SubjectTwenty-one adult men participated in the study.

RESULTS

Portion size had a significant main effect on rice intake (F (1,20)=83, P<0·001) and fullness (F (1,20)=8·0, P=0·010), but no significant effects of bowl size on the outcome variables were found. The interactions between portion size and bowl size on intake and fullness were not significant.

CONCLUSIONS

The sample of Japanese men showed an influence of portion size on food intake. Further research is needed to clarify the combined effects of bowl size and portion size on intake and fullness.

Food deprivation reduces the susceptibility to size-contrast illusions

Hunger, caused by mild amount of food deprivation, is an everyday physiological state familiar to us all. Ongoing research has pinpointed the way hunger affects people's physiological functions as well as their attitudes and allocation of attention toward domain-specific, food-related objects. Yet, little is known about the way food deprivation affects basic perceptual abilities. Here, we utilized size-contrast visual illusions commonly associated with food to explore the way deprivation affects relative processing of food size. In two experiments (N_exp1 = 32 females, mean age: 24.31; N_expt2 = 41 females, 40 males, mean age: 23.84), we examined the effect food deprivation has on participants' susceptibility to the Delboeuf illusion, which biases the perceived size of a neutral or of a food-related object when it is placed within the context of another object (e.g., a pizza is perceived as smaller when placed on a larger plate or tray). The results showed that food deprivation reduces the illusory bias for food-related but not for neutral stimuli. Such reduction in the illusory effect indicates reliance on analytic, rather than on relative processing style, for domain-specific stimuli when in the state of hunger.

Research into food portion size: methodological aspects and applications

Portion sizes for certain foods have been increasing dramatically in recent years alongside obesity rates, concurring with the phenomenon of the portion size effect (more is consumed when more is offered). Portion size may be defined based on different purposes such as for dietary assessment, or therapeutic advice or food labelling, resulting in a variety of measurement methods and specifications. This situation has resulted in disagreements on establishing portion size recommendations by manufacturers, food distributors, restaurants, health professionals and policy makers, contributing to confusion amongst consumers on the amounts of food to be consumed, and potentially increasing the likelihood of overeating and other obesity-related behaviours. Such variability is also reflected in the research field making comparison across studies on portion size difficult. The aim of this review is to provide an overview of definitions and methods used in research to evaluate portion-size related outcomes, including methods to estimate amounts consumed by individuals as part of dietary assessment; methods to analyse cognitive mechanisms related to portion size behaviour; and methods to evaluate the impact of portion size manipulations as well as individual plus environmental factors on portion size behaviour. Special attention has been paid to behavioural studies exploring portion size cognitive processes given the lack of previous methodological reviews in this area. This information may help researchers, clinicians and other stakeholders to establish clearer definitions of portion size in their respective areas of work and to standardise methods to analyse portion size effects.

Dietary Management of Obesity: Cornerstones of Healthy Eating Patterns

Several dietary patterns, both macronutrient and food based, can lead to weight loss. A key strategy for weight management that can be applied across dietary patterns is to reduce energy density. Clinical trials show that reducing energy density is effective for weight loss and weight loss maintenance. A variety of practical strategies and tools can help facilitate successful weight management by reducing energy density, providing portion control, and improving diet quality. The flexibility of energy density gives patients options to tailor and personalize their dietary pattern to reduce energy intake for sustainable weight loss.

An overture to overeating: The cross-modal effects of acoustic pitch on food preferences and serving behavior

Billions of dollars are spent annually with the aim of enticing consumers to purchase food. Yet despite the prevalence of such advertising, little is known about how the actual sensation of this advertising media affects consumer behavior, including consequential choices regarding food. This paper explores the effect of acoustic pitch in food advertising, demonstrating in two studies, including a field study in a live retail environment, how the perception of pitch in advertising can impact food desirability and decisions regarding serving size. In study 1, a field study, pitch affects actual serving sizes and purchase behavior in a live, self-serve retail setting, with low pitch leading to larger serving sizes. Study 2 demonstrates how low pitch increases desire for a food product among hungry consumers, and that this effect is mediated by perceptions of size and how filling consumers believe the product will be. We discuss these results in the context of cross-modal correspondence and mental imagery.

Wine glass size in England from 1700 to 2017: a measure of our time

Wine glass capacity in England has increased sevenfold in 300 years. Can downsizing reduce wine consumption? Theresa Marteau and colleagues investigate

Multisensory influence on eating behavior: Hedonic consumption

Research in obesity has traditionally focused on prevention strategies and treatments aimed at changing lifestyle habits. However, recent research suggests that eating behavior is a habit regulated not only by homeostatic mechanisms, but also by the hedonic pathway that controls appetite and satiety processes. Cognitive, emotional, social, economic, and cultural factors, as well as organoleptic properties of food, are basic aspects to consider in order to understand eating behavior and its impact on health. This review presents a multisensory integrative view of food at both the homeostatic and non-homeostatic levels. This information will be of scientific interest to determine behavior drivers leading to overeating and, thus, to propose effective measures, at both the individual and population levels, for the prevention of obesity and associated metabolic diseases.

Interventions to promote healthy eating choices when dining out: A systematic review of reviews

PURPOSE

To synthesize review research pertaining to the effectiveness of interventions in dining-out settings to reduce food/calorie consumption.

METHODS

A rapid review methodology was employed to focus on synthesized research. A comprehensive search for peer-reviewed systematic reviews from 2010 to 2015 yielded 1,847 citations. Following screening, ten systematic reviews were included.

RESULTS

The 10 included systematic reviews identified 183 primary studies evaluating evidence in three behavioural intervention areas: social models/norms, manipulation of size, and provision of health information. Three systematic reviews evaluating the use of social models/norms found this was an effective intervention for influencing food intake. Five systematic reviews that assessed manipulation of portion/dishware/cutlery size found a small-to-moderate effect on food consumption. Three systematic reviews looked at the provision of health information, which was not effective alone; however, in combination with contextual or interpretive material such as traffic lights or exercise equivalence, this was shown to reduce calorie consumption. One systematic review covered two topic areas.

CONCLUSIONS

The results indicate that policies or interventions that aim to improve healthy choices or consumption when dining out would benefit from harnessing social norms and positive positioning of social identity. Furthermore, provision of health information should always be accompanied by an interpretative guide, such as traffic lights. Manipulation of plate/portion/cutlery size may be effective; however, the effect size is small and further research is required to investigate whether this effect is retained in overweight or obese populations. Statement of contribution What is already known on this subject? Eating behaviours (food choices, consumption) have played a role in the obesity epidemic. Behavioural 'nudges' have tried to increase healthier eating choices. What does this study add? Social norms and modelling have a strong influence in both directions on how much people consume. Provision of nutritional information needs to be paired with interpretative aids (e.g., traffic lights). Manipulation of portion size is less effective in overweight populations.

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.

Portion Size: Latest Developments and Interventions

PURPOSE OF REVIEW

The aim of this review is to provide an overview of (1) underlying mechanisms of the effect of portion size on energy intake, (2) external factors explaining the portion size effect and (3) interventions and measurements aimed at food portion size.

RECENT FINDINGS

Previous studies have shown that portion sizes have increased in recent decades. Many experimental studies have been conducted to unravel the mechanisms underlying the portion-size effect on food intake (e.g. the appropriateness mechanism, the 'unit bias' mechanism, the 'previous experience/expectation' mechanism, the 'visual cue' mechanism and the 'bite size' mechanism). In addition, external factors have been found to drive food portion selection and consumption (e.g. value for money, mindless eating, levels of awareness, estimation bias. Research on several interventions (ranging from 'providing information' to 'eliminating choice') have been conducted, but remain scarce, especially intervention studies in which portion size is a key focus in weight loss. Moreover, only three new instruments with respect to portion control behavior have been developed. There is considerable evidence for the portion-size effect on energy intake. However, the work on interventions targeting portion size and measurements for portion control behavior are limited. Moreover, from the literature it is not yet clear what type of interventions work best, for whom and in what context.

Effect of plate size on meal energy intake in normal weight women

BACKGROUND/OBJECTIVES

Use of smaller plates to control food intake is a commonly recommended strategy for restricting energy intake, despite conflicting results. Therefore, the aim of this study was to examine whether or not three different sizes of plates influence energy intake during a multi-itemed buffet meal in normal weight women.

SUBJECTS/METHODS

This was a cross-over study conducted on 37 female participants aged 19-25 years with normal BMI levels. Participants were recruited from Hacettepe University and the surrounding community. On experimental days, participants ate a standard breakfast and were then randomly assigned to eat lunch using a small (19 cm), medium (23 cm), or large (28 cm) diameter plate. Visual analogue scale (VAS) scores on sensory and satiety outcomes were measured for all meals. Energy and macronutrient intakes during lunch were recorded.

RESULTS

There was no evidence that use of a smaller plate size reduced energy or specific macronutrient intake during the free choice lunch meal. Multiple visits to the serving table were not associated with energy or macronutrient intake. Plate size did not affect VAS scores during the test days.

CONCLUSIONS

Plate size did not influence energy intake, meal composition, or palatability in normal weight women during a multi-itemed open buffet lunch. Studies in natural settings at the population level are needed to clarify current outcomes.

The effect of heightened awareness of observation on consumption of a multi-item laboratory test meal in females

Human eating behaviour is often studied in the laboratory, but whether the extent to which a participant believes that their food intake is being measured influences consumption of different meal items is unclear. Our main objective was to examine whether heightened awareness of observation of food intake affects consumption of different food items during a lunchtime meal. One hundred and fourteen female participants were randomly assigned to an experimental condition designed to heighten participant awareness of observation or a condition in which awareness of observation was lower, before consuming an ad libitum multi-item lunchtime meal in a single session study. Under conditions of heightened awareness, participants tended to eat less of an energy dense snack food (cookies) in comparison to the less aware condition. Consumption of other meal items and total energy intake were similar in the heightened awareness vs. less aware condition. Exploratory secondary analyses suggested that the effect heightened awareness had on reduced cookie consumption was dependent on weight status, as well as trait measures of dietary restraint and disinhibition, whereby only participants with overweight/obesity, high disinhibition or low restraint reduced their cookie consumption. Heightened awareness of observation may cause females to reduce their consumption of an energy dense snack food during a test meal in the laboratory and this effect may be moderated by participant individual differences.

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We examined the effect of heightened awareness of observation on food intake.

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This caused female participants to eat less of an energy dense snack food.

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This effect was moderated by weight status and trait eating behaviour measures.

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Heightened awareness of observation had little effect on intake of other foods.

Sensory influences on food intake control: moving beyond palatability

The sensory experience of eating is an important determinant of food intake control, often attributed to the positive hedonic response associated with certain sensory cues. However, palatability is just one aspect of the sensory experience. Sensory cues based on a food's sight, smell, taste and texture are operational before, during and after an eating event. The focus of this review is to look beyond palatability and highlight recent advances in our understanding of how certain sensory characteristics can be used to promote better energy intake control. We consider the role of visual and odour cues in identifying food in the near environment, guiding food choice and memory for eating, and highlight the ways in which tastes and textures influence meal size and the development of satiety after consumption. Considering sensory characteristics as a functional feature of the foods and beverages we consume provides the opportunity for research to identify how sensory enhancements might be combined with energy reduction in otherwise palatable foods to optimize short-term energy intake regulation in the current food environment. Moving forward, the challenge for sensory nutritional science will be to assess the longer-term impact of these principles on weight management.

Portion, package or tableware size for changing selection and consumption of food, alcohol and tobacco

BACKGROUND

Overeating and harmful alcohol and tobacco use have been linked to the aetiology of various non-communicable diseases, which are among the leading global causes of morbidity and premature mortality. As people are repeatedly exposed to varying sizes and shapes of food, alcohol and tobacco products in environments such as shops, restaurants, bars and homes, this has stimulated public health policy interest in product size and shape as potential targets for intervention.

OBJECTIVES

1) To assess the effects of interventions involving exposure to different sizes or sets of physical dimensions of a portion, package, individual unit or item of tableware on unregulated selection or consumption of food, alcohol or tobacco products in adults and children.2) To assess the extent to which these effects may be modified by study, intervention and participant characteristics.

SEARCH METHODS

We searched CENTRAL, MEDLINE, EMBASE, PsycINFO, eight other published or grey literature databases, trial registries and key websites up to November 2012, followed by citation searches and contacts with study authors. This original search identified eligible studies published up to July 2013, which are fully incorporated into the review. We conducted an updated search up to 30 January 2015 but further eligible studies are not yet fully incorporated due to their minimal potential to change the conclusions.

SELECTION CRITERIA

Randomised controlled trials with between-subjects (parallel-group) or within-subjects (cross-over) designs, conducted in laboratory or field settings, in adults or children. Eligible studies compared at least two groups of participants, each exposed to a different size or shape of a portion of a food (including non-alcoholic beverages), alcohol or tobacco product, its package or individual unit size, or of an item of tableware used to consume it, and included a measure of unregulated selection or consumption of food, alcohol or tobacco.

DATA COLLECTION AND ANALYSIS

We applied standard Cochrane methods to select eligible studies for inclusion and to collect data and assess risk of bias. We calculated study-level effect sizes as standardised mean differences (SMDs) between comparison groups, measured as quantities selected or consumed. We combined these results using random-effects meta-analysis models to estimate summary effect sizes (SMDs with 95% confidence intervals (CIs)) for each outcome for size and shape comparisons. We rated the overall quality of evidence using the GRADE system. Finally, we used meta-regression analysis to investigate statistical associations between summary effect sizes and variant study, intervention or participant characteristics.

MAIN RESULTS

The current version of this review includes 72 studies, published between 1978 and July 2013, assessed as being at overall unclear or high risk of bias with respect to selection and consumption outcomes. Ninety-six per cent of included studies (69/72) manipulated food products and 4% (3/72) manipulated cigarettes. No included studies manipulated alcohol products. Forty-nine per cent (35/72) manipulated portion size, 14% (10/72) package size and 21% (15/72) tableware size or shape. More studies investigated effects among adults (76% (55/72)) than children and all studies were conducted in high-income countries - predominantly in the USA (81% (58/72)). Sources of funding were reported for the majority of studies, with no evidence of funding by agencies with possible commercial interests in their results.A meta-analysis of 86 independent comparisons from 58 studies (6603 participants) found a small to moderate effect of portion, package, individual unit or tableware size on consumption of food (SMD 0.38, 95% CI 0.29 to 0.46), providing moderate quality evidence that exposure to larger sizes increased quantities of food consumed among children (SMD 0.21, 95% CI 0.10 to 0.31) and adults (SMD 0.46, 95% CI 0.40 to 0.52). The size of this effect suggests that, if sustained reductions in exposure to larger-sized food portions, packages and tableware could be achieved across the whole diet, this could reduce average daily energy consumed from food by between 144 and 228 kcal (8.5% to 13.5% from a baseline of 1689 kcal) among UK children and adults. A meta-analysis of six independent comparisons from three studies (108 participants) found low quality evidence for no difference in the effect of cigarette length on consumption (SMD 0.25, 95% CI -0.14 to 0.65).One included study (50 participants) estimated a large effect on consumption of exposure to differently shaped tableware (SMD 1.17, 95% CI 0.57 to 1.78), rated as very low quality evidence that exposure to shorter, wider bottles (versus taller, narrower bottles) increased quantities of water consumed by young adult participants.A meta-analysis of 13 independent comparisons from 10 studies (1164 participants) found a small to moderate effect of portion or tableware size on selection of food (SMD 0.42, 95% CI 0.24 to 0.59), rated as moderate quality evidence that exposure to larger sizes increased the quantities of food people selected for subsequent consumption. This effect was present among adults (SMD 0.55, 95% CI 0.35 to 0.75) but not children (SMD 0.14, 95% CI -0.06 to 0.34).In addition, a meta-analysis of three independent comparisons from three studies (232 participants) found a very large effect of exposure to differently shaped tableware on selection of non-alcoholic beverages (SMD 1.47, 95% CI 0.52 to 2.43), rated as low quality evidence that exposure to shorter, wider (versus taller, narrower) glasses or bottles increased the quantities selected for subsequent consumption among adults (SMD 2.31, 95% CI 1.79 to 2.83) and children (SMD 1.03, 95% CI 0.41 to 1.65).

AUTHORS' CONCLUSIONS

This review found that people consistently consume more food and drink when offered larger-sized portions, packages or tableware than when offered smaller-sized versions. This suggests that policies and practices that successfully reduce the size, availability and appeal of larger-sized portions, packages, individual units and tableware can contribute to meaningful reductions in the quantities of food (including non-alcoholic beverages) people select and consume in the immediate and short term. However, it is uncertain whether reducing portions at the smaller end of the size range can be as effective in reducing food consumption as reductions at the larger end of the range. We are unable to highlight clear implications for tobacco or alcohol policy due to identified gaps in the current evidence base.