Portion size and later food intake: evidence on the "normalizing" effect of reducing food portion sizes

Impact on beer sales of removing the pint serving size: An A-B-A reversal trial in pubs, bars, and restaurants in England

BACKGROUND

Smaller serving sizes could contribute towards reducing alcohol consumption across populations and thereby decrease the risk of 7 cancers and other diseases. To our knowledge, the current study is the first to assess the impact on beer, lager, and cider sales (hereafter, for ease, referred to just as "beer sales") of removing the largest draught serving size (1 imperial pint) from the options available in licensed premises under real-word conditions.

METHODS AND FINDINGS

The study was conducted between February and May 2023, in 13 licensed premises in England. It used an A-B-A reversal design, set over 3 consecutive 4-weekly periods with "A" representing the nonintervention periods during which standard serving sizes were served, and "B" representing the intervention period when the largest serving size of draught beer (1 imperial pint (568 ml)) was removed from existing ranges so that the largest size available was two-thirds of a pint. Where two-third pints were not served, the intervention included introducing this serving size in conjunction with removing the pint serving size. The primary outcome was the mean daily volume of all beer sold, including draught, bottles, and cans (in ml), extracted from electronic sales data. Secondary outcomes were mean daily volume of wine sold (ml) and daily revenue (£). Thirteen premises completed the study, 12 of which did so per protocol and were included in the primary analysis. After adjusting for prespecified covariates, the intervention resulted in a mean daily change of -2,769 ml (95% CI [-4,188, -1,578] p < 0.001) or -9.7% (95% CI [-13.5%, -6.1%] in beer sold. The daily volume of wine sold increased during the intervention period by 232 ml (95% CI [13, 487], p = 0.035) or 7.2% (95% CI [0.4%, 14.5%]). Daily revenues decreased by 5.0% (95% CI [9.6%, -0.3%], p = 0.038).

CONCLUSIONS

Removing the largest serving size (the imperial pint) for draught beer reduced the volume of beer sold. Given the potential of this intervention to reduce alcohol consumption, it merits consideration in alcohol control policies.

TRIAL REGISTRATION

ISRCTN.com ISRCTN18365249.

Impact on sales of adding a smaller serving size of beer and cider in licensed premises: an A-B-A reversal design

BACKGROUND

Smaller serving sizes of alcoholic drinks could reduce alcohol consumption across populations thereby lowering the risk of many diseases. The effect of modifying the available range of serving sizes of beer and cider in a real-world setting has yet to be studied. The current study assessed the impact on beer and cider sales of adding a serving size of draught beer and cider (2/3 pint) that was between the current smallest (1/2 pint) and largest (1 pint) standard serving sizes.

METHODS

Twenty-two licensed premises in England consented to taking part in the study. The study used an ABA reversal design, set over three 4-weekly periods, with A representing the non-intervention periods, during which standard serving sizes were served and B the intervention period when a 2/3 pint serving size of draught beer and cider was added to the existing range, along with smaller 1/2 pint and larger 1 pint serving sizes. The primary outcome was the daily volume of beer and cider sold, extracted from sales data.

RESULTS

Fourteen premises started the study, of which thirteen completed it. Twelve of those did so per protocol and were included in the primary analysis. After adjusting for pre-specified covariates, the intervention did not have a significant effect on the volume of beer and cider sold per day (3.14 ml; 95%CIs -2.29 to 8.58; p = 0.257).

CONCLUSIONS

In licensed premises, there was no evidence that adding a smaller serving size for draught beer and cider (2/3 pint) when the smallest (1/2 pint) and largest (1 pint) sizes were still available, affected the volume of beer and cider sold. Studies are warranted to assess the impact of removing the largest serving size.

TRIAL REGISTRATION

ISRCTN: https://doi.org/10.1186/ISRCTN33169631 (08/09/2021), OSF: https://osf.io/xkgdb/ (08/09/2021).

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.

Downsizing food: a systematic review and meta-analysis examining the effect of reducing served food portion sizes on daily energy intake and body weight

Portion sizes of many foods have increased over time. However, the size of effect that reducing food portion sizes has on daily energy intake and body weight is less clear. We used a systematic review methodology to identify eligible articles that used an experimental design to manipulate portion size served to human participants and measured energy intake for a minimum of 1 d. Searches were conducted in September 2020 and again in October 2021. Fourteen eligible studies contributing eighty-five effects were included in the primary meta-analysis. There was a moderate-to-large reduction in daily energy intake when comparing smaller v. larger portions (Standardised Mean Difference (SMD) = -0·709 (95 % CI: -0·956, -0·461), approximately 235 kcal (983·24 kJ)). Larger reductions to portion size resulted in larger decreases in daily energy intake. There was evidence of a curvilinear relationship between portion size and daily energy intake; reductions to daily energy intake were markedly smaller when reducing portion size from very large portions. In a subset of studies that measured body weight (four studies contributing five comparisons), being served smaller v. larger portions was associated with less weight gain (0·58 kg). Reducing food portion sizes may be an effective population-level strategy to prevent weight gain.

The Economics of a "portion size reduction" policy

This study develops novel models of heterogeneous consumer preferences for different dining options and imperfect competition among food suppliers to analyze the market and welfare effects of portion size reduction (PSR) for food away from home. Different scenarios on the nature of differentiation of the dining options, the information available to consumers, and their response to links between portion size and obesity, food waste, and climate change are considered within this framework. The market and welfare effects of the policy are quantified using a simulation analysis. The analysis shows that the market and welfare effects of the policy are case-specific and dependent on the relative magnitude of the cost and utility effects of PSR, the strength of the consumer preference for dining out, and the food suppliers' initial costs and degree of market power in the relevant markets. The policy can create winners and losers among consumers and accounting for consumer heterogeneity, as done in this study, is essential for capturing the asymmetric welfare effects of PSR. Intriguingly, consumers and suppliers can benefit from PSR even without accounting for any health or/and environmental benefits of reduced portion sizes.

Evaluating augmented reality for 'real life' teaching of food portion concepts

BACKGROUND

Estimation of food portions is a vital skill for dietitians, which is developed during formal nutrition training. Skill development is often accomplished by training with food portion estimation tools. These tools can vary in design but evaluations often reveal them to be limited in their effectiveness and generally impractical for everyday use. The aim of this study was to develop and evaluate an augmented reality (AR) tool for the estimation food portions.

METHODS

An online, quasi-experimental, randomised pre-test post-test study was conducted to evaluate the effectiveness of three food portion tools with nutrition students. These tools consisted of an online, AR, and an infographic tool (control). Students tested 10 different food images and were asked to estimate food portion sizes with and without assistance of a portion tool to determine absolute error, relative error, and overall improvement in estimation.

RESULTS

A total of 33 participants enrolled in the study with 26 (72.0%) completing the study. The mean absolute error was lowest in the online group (53.0%), followed by AR (59.5%) and control (64.0%). Relative error scores revealed higher accuracy for the AR group (45.5%) followed by online (43.5%), and control group (29.0%). Overall improvement in estimation was highest in the AR group (+12.2%) followed by the online (+11.6%) tool with a decrease seen for the infographic (-1.7%) tool.

CONCLUSIONS

The use of technology, notably AR technology, may provide some advantage when training nutrition students in food portion estimation, although further investigation is advised.

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

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

Impact of Sizes of Servings, Glasses and Bottles on Alcohol Consumption: A Narrative Review

This review summarises the evidence on the impact of serving and container size on how much people drink, interventions that have the potential to reduce alcohol consumption across populations, thereby improving health. A rapid search identified 10 published reports of 15 studies and 1 review. Four studies focused on serving size, eight studies and the review on glass size, two studies on bottle size and one on both glass and bottle size. Twelve studies and the review focused on wine, one study on beer and two on both. All were conducted in England, by just two research groups. Removing the largest serving size of wine decreased wine sales by 7.6% (95% CI -12.3%, -2.9%) in a study in 21 licenced premises, reflecting findings from two prior studies in semi-naturalistic settings. Adding a serving size for beer that was a size smaller than the largest was assessed in one study in 13 licenced premises, with no evident effect. Reducing the size of wine glasses in restaurants decreased wine sales by 7.3% (95% CI -13.5%, -1.5%) in a mega-analysis of eight datasets from studies in five licensed premises. Using smaller wine glasses at home may also reduce consumption, but the evidence from just one study is less certain. No studies have assessed the impact of glass size for drinking beer. The effect of bottles smaller than the standard 750 mL on wine consumed at home was assessed in two studies: 500 mL bottles reduced consumption by 4.5% (95% CI -7.9%, -1.0%) in one study, but in another, using 375 mL bottles there was no evident effect. No studies assessed the impact of bottle or other container size for drinking beer. Reducing the size of servings, glasses and bottles could reduce wine consumption across populations. The impact of similar interventions for reducing consumption of other alcoholic drinks awaits evaluation. Further studies are also warranted to assess the generalisability of existing evidence.

Systematic review of the portion size norm of discretionary foods

CONTEXT

Portion size norm is described as the perception of how much of a given food people choose to eat. Reducing the portion size norm of foods that are high in saturated fat, added sugar, and added salt toward smaller sizes might be a potential strategy to promote appropriate portion size selections. However, an overview of existing portion size norms for discretionary foods has yet to be established.

OBJECTIVE

The aim of this systematic review was to examine the portion size norm of discretionary foods and assess the methodologies used to investigate the norm.

DATA SOURCES

The literature search was conducted in 6 databases following the PRISMA guidelines (from inception to January 2022).

DATA EXTRACTION

Forty studies were eligible and grouped into 3 categories by portion size norm measures: normal (n = 26), appropriate (n = 8), and preferred portion sizes (n = 3). Study quality was assessed using the Joanna Briggs Institute Critical Appraisal Tools.

DATA ANALYSIS

A wide range of portion sizes were considered normal for each food type, with means/medians varying from 2- to 4-fold among studies. Studies differed considerably in design, with variables including the setting, food type, food presentation, the manner in which portion-size-related questions were formulated, and the range and number of displayed serving size options. The quality of reviewed studies was mixed (25 studies had low or moderate risk of bias, 15 had high risk of bias), and the method of assessing portion size was not validated in 15 of 33 quantitative studies.

CONCLUSION

The assessment of portion size in future studies should be conducted using tools that are validated for the population of interest so that more definitive conclusions can be drawn regarding portion size norms for discretionary foods.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42021249911.

Changes in Package Sizes of Savoury Snacks through Exploration of Euromonitor and Industry Perspectives

Portion sizes of many energy-dense and nutrient-poor foods and drinks have increased in the past decade, whereas our understanding of the pattern of changes in package sizes remains limited. This study aimed to determine changing trends in sales and package sizes of savoury snacks in Australia, the USA, Japan and Hong Kong, and to investigate industry perspectives for these changes. Sales data (units per capita) between 2006−2020 on savoury snacks were extracted from the Euromonitor International database. Industry perspectives on package size changes were extracted systematically from selected databases, company reports and related websites following the PRISMA-ScR guidelines. The findings showed that sales per capita of savoury snacks of all package sizes increased across all four countries/regions between 2006−2020. Although changes in the proportion of smaller (<100 g) versus larger (>100 g) package size sales in each country/region over time were modest, Japan and Hong Kong exhibited a consistently higher proportion of smaller package sales compared with Australia and the USA (83.3%, 64.4%, 44.3%, 20.2%, respectively). Industry perspectives showed that increasing consumer health consciousness, demands for convenience and portion control were the main contributors to decreasing package sizes of savoury snacks. Industry reports from 2020 showed an increase in larger package size sales due to consumer purchasing behaviour amidst the COVID-19 pandemic.

Gender, Age, Hunger, and Body Mass Index as Factors Influencing Portion Size Estimation and Ideal Portion Sizes

Portion sizes of meals have been becoming progressively larger which contributes to the onset of obesity. So far, little research has been done on the influence of body weight on portion size preferences. Therefore, we assessed whether Body Mass Index (BMI), as well as other selected factors, contribute to the estimation of food portions weight and the subjective perception of portion sizes. Through online questionnaires, the participants were asked to estimate the weight of pictured foods in the first study. In the second study, the participants indicated how the depicted varying portion sizes of different meals relate to their actual consumed real-life portion sizes. A total of 725 and 436 individuals were included in the statistical analysis in the first and second study, respectively. BMI and gender had a small effect on the capacity to estimate the weight of foods. The main predictor for portion size choices was the factor gender with men estimating ideal portion sizes as larger than women. Further, age and hunger together with external and restrictive eating behaviors were among the deciding factors for portion size choices. As expected, externally motivated eaters chose bigger portions while restrictive individual smaller ones. Gender- and age-related differences in portion size preferences likely reflect distinct energy requirements. The individuals with a higher BMI do not differ strongly from other BMI groups in their portion-related preferences. Therefore, other factors such as meal frequency, snacking, or a lifestyle, may contribute more to the onset, development, and maintenance of overweight.

The Effect of Downsizing Packages of Energy-Dense, Nutrient-Poor Snacks and Drinks on Consumption, Intentions, and Perceptions-A Scoping Review

The single-serve packaging of discretionary foods is becoming increasingly popular, but evidence is limited on whether smaller package sizes can reduce food intake. The aim of this scoping review is to assess the effect of reducing the package size of energy-dense, nutrient-poor (EDNP) snacks and drinks on consumption, intentions, and perception, and to examine the effects of potential moderators or mediators. The search was conducted in six selected databases and grey literature sources, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for the scoping review process (PRISMA-ScR) guidelines. After screening 5562 articles, 30 articles comprising 47 intervention studies were included. Twelve of 15 studies found a significant effect in lowering the actual or intended consumption when a single smaller package was offered compared with a single larger package. When the total serving size was held constant between varying package conditions, such as a multipack, single package, or unpackaged, the results on the actual and intended consumption were inconsistent and varied according to the presence of moderators. Overall, these findings suggest that an overall reduction in the size of a single package is a more promising strategy than providing multipacks to reduce consumption. Changes to the current food environment to promote single smaller packages of EDNP snacks and drinks are necessary to support the better selection of appropriate portion sizes and reduce consumption.

Portion Sizes of Ultra-Processed Foods in the United States, 2002 to 2021

Objectives. To assess the US food industry's response to calls from public health authorities to reduce portion sizes by comparing current with past sizes of selected examples of single-serve ultra-processed packaged and fast foods. Methods. We obtained manufacturers' information about current portion sizes and compared it with sizes when first introduced and in 2002. Results. Few companies in our sample reduced portion sizes since 2002; all still sold portions of ultra-processed foods in up to 5-times-larger sizes than when first introduced. Conclusions. Policies and practices focused on reducing portion size could help discourage the consumption of excessive amounts of ultra-processed foods. (Am J Public Health. 2021;111(12):2223-2226. https://doi.org/10.2105/AJPH.2021.306513).

The nurse's role in providing strategies and advice on weight management

Maintaining a healthy weight is a concern for a large proportion of adults in the UK, with obesity rates having almost doubled between 1993 and 2011. With overweight and obesity linked to several diseases and health conditions, nurses are often tasked with raising the subject with their clients/patients and advising on lifestyle modifications. This article examines ways to identify whether a person needs to lose weight and establishing targets. It then reviews the evidence base for different approaches to weight management currently available and the advice nurses can provide.

Impact of decreasing the proportion of higher energy foods and reducing portion sizes on food purchased in worksite cafeterias: A stepped-wedge randomised controlled trial

BACKGROUND

Overconsumption of energy from food is a major contributor to the high rates of overweight and obesity in many populations. There is growing evidence that interventions that target the food environment may be effective at reducing energy intake. The current study aimed to estimate the effect of decreasing the proportion of higher energy (kcal) foods, with and without reducing portion size, on energy purchased in worksite cafeterias.

METHODS AND FINDINGS

This stepped-wedge randomised controlled trial (RCT) evaluated 2 interventions: (i) availability: replacing higher energy products with lower energy products; and (ii) size: reducing the portion size of higher energy products. A total of 19 cafeterias were randomised to the order in which they introduced the 2 interventions. Availability was implemented first and maintained. Size was added to the availability intervention. Intervention categories included main meals, sides, cold drinks, snacks, and desserts. The study setting was worksite cafeterias located in distribution centres for a major United Kingdom supermarket and lasted for 25 weeks (May to November 2019). These cafeterias were used by 20,327 employees, mainly (96%) in manual occupations. The primary outcome was total energy (kcal) purchased from intervention categories per day. The secondary outcomes were energy (kcal) purchased from nonintervention categories per day, total energy purchased per day, and revenue. Regression models showed an overall reduction in energy purchased from intervention categories of -4.8% (95% CI -7.0% to -2.7%), p < 0.001 during the availability intervention period and a reduction of -11.5% (95% CI -13.7% to -9.3%), p < 0.001 during the availability plus size intervention period, relative to the baseline. There was a reduction in energy purchased of -6.6% (95% CI -7.9% to -5.4%), p < 0.001 during the availability plus size period, relative to availability alone. Study limitations include using energy purchased as the primary outcome (and not energy consumed) and the availability only of transaction-level sales data per site (and not individual-level data).

CONCLUSIONS

Decreasing the proportion of higher energy foods in cafeterias reduced the energy purchased. Decreasing portion sizes reduced this further. These interventions, particularly in combination, may be effective as part of broader strategies to reduce overconsumption of energy from food in out-of-home settings.

TRIAL REGISTRATION

ISRCTN registry ISRCTN87225572.

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.

Trends in Sales and Industry Perspectives of Package Sizes of Carbonates and Confectionery Products

Discretionary food package sizes are an important environmental cue that can affect the amount of food consumed. The aim of this study was to determine sales trends and reported food industry perspectives for changing food package sizes of carbonates and confectionery between 2005 and 2019. Changes in package sizes of carbonates and confectionery were investigated in Australia, the USA, Canada, and the UK. Sales data (units per capita and compound annual growth rate between 2005 and 2019) were extracted from the Euromonitor database. Qualitative data (market research reports) on industry perspectives on package size changes were extracted from industry and marketing databases. Carbonate sales data showed increased growth of smaller package sizes (<300 mL) and a decrease in sales of larger package sizes (≥2000 mL) in all four countries. In contrast, confectionery sales data showed no consistent trends across the selected countries. No growth was observed for smaller confectionery package sizes but an increase in growth of larger package sizes (50–99 g, >100 g), including share packages, was observed in Australia. Qualitative data (n = 92 articles) revealed key reasons identified by industry for changes in package size related to consumer health awareness, portion size control, convenience, market growth, and government or industry initiatives. Monitoring of discretionary food package sizes provides additional insights into consumers’ food environment.

Individual differences and moderating participant characteristics in the effect of reducing portion size on meal energy intake: Pooled analysis of three randomized controlled trials

Portion size impacts on the amount of energy consumed during a meal. However, research findings on participant characteristics that moderate the effect of portion size on energy intake are mixed. Using data pooled across three randomized control trials, we examined the impact of reducing meal portion size on meal energy intake in 111 adult participants varying in sex (55 M, 56 F), body weight (BMI range = 19-42) and a broad range of participant characteristics, including usual portion size, restrained, emotional and external eating, satiety responsiveness, plate clearing tendencies, concerns about wasting food and self-control. In each trial, a repeated-measures design was used and participants consumed three ad-libitum lunchtime meals differing in portion size; large-normal portion size condition (100%) vs. small-normal portion size condition (~ 75%) vs. smaller than normal portion size condition (~ 50%). In mixed ANOVAs, we did not find convincing evidence that any participant characteristic reliably moderated the impact that reducing portion size had on energy intake. For the majority of participants energy intake decreased when portion size was reduced and it was more common for participants to consistently reduce their energy intake than consume a similar amount when portion size was reduced. We also found little evidence that a sub-group of participants existed whose energy intake was consistently resistant to portion size reductions. Portion size may be a universal driver of energy intake, as reducing meal portion size appears to decrease meal energy intake among most people. Food portion downsizing may therefore be an equitable intervention approach to reducing population level energy intake.

Impact of bottle size on in-home consumption of wine: a randomized controlled cross-over trial

AIM

To assess the impact of purchasing wine in 50 cl bottles compared with 75 cl bottles on the amount of wine consumed at home.

DESIGN

Cross-over randomized controlled trial with a 'usual behaviour' period of a maximum of 3 weeks between conditions.

SETTING

Households in the United Kingdom.

PARTICIPANTS

One hundred and eighty-six households that consumed between two and eight 75 cl bottles of wine each week.

INTERVENTION

Households were randomized to the order in which they purchased wine in two bottle sizes. During two 14-day intervention periods, households purchased a pre-set volume of wine-based on their baseline self-reported weekly consumption-in either 75 cl bottles or 50 cl bottles. On days 7 and 14 of each study period, participating households sent photographs of each purchased wine bottle.

MEASUREMENTS

The primary outcome was the volume of study wine in millilitres (ml) consumed during each study period estimated through returned photographs. The secondary outcome was the rate of consumption measured by the mean number of days taken to drink 1.5 litres from each bottle size.

FINDINGS

One hundred and sixty-six of 186 enrolled households satisfactorily completed the study. After accounting for pre-specified covariates, 191.1 ml [95% confidence interval (CI) = 42.03-339.2] or 4.5% (95% CI = 1.0-7.9%) more wine was consumed per 14-day period from 75-cl bottles than from 50-cl bottles. Consumption was 5.8% faster (95% CI = -10.9 to -0.4%) from 75 cl bottles than from 50 cl bottles.

CONCLUSIONS

Consuming wine at home from 50 cl bottles, compared with 75 cl bottles, may reduce both amount consumed and rate of consumption.

An Overview of the Sociological and Environmental Factors Influencing Eating Food Behavior in Canada

This review extensively discusses various socio environmental factors affecting eating behavior of the general public within Canada including the development and implementation of national policies. A framework representing the determinants of healthy eating can be grouped into four categories i.e., the individual determinants, the economic environment, the social environment and the physical environment. This framework allowed for addressing food insecurity and social economic ecosystem of Canadians. Lastly, we investigate the role in which biotechnology plays in improving food security and addresses the significant impact biotechnology has contributed toward on agriculture and the food market. Overall, this review using such sources as Web of Science, Pub Med and Scopus provides significant contribution toward understanding the social economic environment and eating behavior of people living in Canada. In conclusion, this has led to identify a research gap as there is a significant need to address the development and implementation of policies in the food and nutrition environment.

The Kids Obesity Prevention Program: Cluster Randomized Controlled Trial to Evaluate a Serious Game for the Prevention and Treatment of Childhood Obesity

Background

Health games provide opportunities for the treatment and prevention of childhood obesity. We developed a motion-controlled serious game for children that addresses 3 core topics of nutrition, physical activity, and stress coping. It is the first serious game that extensively targets the dietary energy density principle (DED-P) in relation to nutrition. The game is intended to provide an additional educational component for the prevention and treatment of obesity in children.

Objective

The Kids Obesity Prevention study aimed to evaluate the newly developed game and to evaluate how well children are able to understand and apply the DED-P.

Methods

This cluster randomized controlled trial collected data from 82 primary school children aged 9 to 12 years and their parents at baseline (T0), at 2 weeks after study commencement (T1), and at the 4-week follow-up (T2). The dropout rate was 3.6%. The intervention group (IG) played the game within 2 weeks (2 sessions with different game modules). One part of the game involves selection of food with the lower energy density when presented with a pair of foods. This allows assessment of whether the children have understood the DED-P and whether they can apply it to unknown foods under time pressure. The control group (CG) received a brochure about the food pyramid concept and physical activity. The primary outcome was the gain in knowledge (nutrition and stress coping) and measured with a pretested questionnaire. The secondary outcomes were the maintenance of knowledge, application of the DED-P, feelings during game play, game acceptance, and behavioral measures (physical activity, media consumption, and dietary intake).

Results

The knowledge score ranging from 0 to 100 increased from T0 (IG: 53 [SD 10], CG: 50 [SD 11]) to T1 (IG: 69 [SD 11], CG: 52 [SD 12]) in IG versus CG (P<.001). At T2, the knowledge score of IG remained at the same level as that of T1. Game data showed that after DED-P education, the classification under time pressure of unknown versus known food pairs according to their DED category was similar (hit rate around 70%). Overall, 95% of the children liked the game very much or much. No group changes were observed at the behavioral level.

Conclusions

The Kids Obesity Prevention program sustainably increased knowledge in the areas of nutrition and stress coping, and children were able to apply the DED-P.

Trial Registration

ClinicalTrials.gov NCT02551978; https://clinicaltrials.gov/ct2/show/NCT02551978

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

BACKGROUND

Smaller portions may help to reduce energy intake. However, there may be a limit to the magnitude of the portion size reduction that can be made before consumers respond by increasing intake of other food immediately or at later meals. We tested the theoretical prediction that reductions to portion size would result in a significant reduction to daily energy intake when the resulting portion was visually perceived as 'normal' in size, but that a reduction resulting in a 'smaller than normal' portion size would cause immediate or later additional eating.

METHODS

Over three 5-day periods, daily energy intake was measured in a controlled laboratory study using a randomized crossover design (N = 30). The served portion size of the main meal component of lunch and dinner was manipulated in three conditions: 'large-normal' (747 kcal), 'small-normal' (543 kcal), and 'smaller than normal' (339 kcal). Perceived 'normality' of portion sizes was determined by two pilot studies. Ad libitum daily energy intake from all meals and snacks was measured.

RESULTS

Daily energy intake in the 'large-normal' condition was 2543 kcals. Daily energy intake was significantly lower in the 'small-normal' portion size condition (mean difference - 95 kcal/d, 95% CI [- 184, - 6], p = .04); and was also significantly lower in the 'smaller than normal' than the 'small-normal' condition (mean difference - 210 kcal/d, 95% CI [- 309, - 111], p < .001). Contrary to predictions, there was no evidence that the degree of additional food consumption observed was greater when portions were reduced past the point of appearing normal in size.

CONCLUSIONS

Reductions to the portion size of main-meal foods resulted in significant decreases in daily energy intake. Additional food consumption did not offset this effect, even when portions were reduced to the point that they were no longer perceived as being normal in size.

TRIAL REGISTRATION

Prospectively registered protocol and analysis plan: https://osf.io/natws/; retrospectively registered: https://clinicaltrials.gov/ct2/show/NCT03811210.

Increasing the proportion of healthier foods available with and without reducing portion sizes and energy purchased in worksite cafeterias: protocol for a stepped-wedge randomised controlled trial

BACKGROUND

Overconsumption of energy from food contributes to high rates of overweight and obesity in many populations. A promising set of interventions tested in pilot studies in worksite cafeterias, suggests energy intake may be reduced by increasing the proportion of healthier - i.e. lower energy - food options available, and decreasing portion sizes. The current study aims to assess the impact on energy purchased of i. increasing the proportion of lower energy options available; ii. combining this with reducing portion sizes, in a full trial.

METHODS

A stepped-wedge randomised controlled trial in 19 worksite cafeterias, where the proportion of lower energy options available in targeted food categories (including main meals, snacks, and cold drinks) will be increased; and combined with reduced portion sizes. The primary outcome is total energy (kcal) purchased from targeted food categories using a pooled estimate across all sites. Follow-up analyses will test whether the impact on energy purchased varies according to the extent of intervention implementation.

DISCUSSION

This study will provide the most reliable estimate to date of the effect sizes of two promising interventions for reducing energy purchased in worksite cafeterias.

TRIAL REGISTRATION

The study was prospectively registered on ISRCTN (date: 24.05.19; TRN: ISRCTN87225572; doi: https://doi.org/10.1186/ISRCTN87225572).

Served Portion Sizes Affect Later Food Intake Through Social Consumption Norms

Portion sizes of commercially available foods have increased, and there is evidence that exposure to portion sizes recalibrates what is perceived as 'normal' and subsequently, how much food is selected and consumed. The present study aims to explore the role of social (descriptive and injunctive) and personal portion size norms in this effect. Across two experiments, participants were either visually exposed to (Study 1, N = 329) or actually served (Study 2, N = 132) a smaller or larger than normal food portion. After 24 h, participants reported their intended consumption (Study 1) or served themselves and consumed (Study 2) a portion of that food and reported perceived portion size norms. In Study 1, visual exposure to portion size did not significantly affect intended consumption and perceived portion size norms. In Study 2, participants consumed a smaller portion of food when they were served a smaller rather than a larger portion the previous day, which was mediated by perceived descriptive and injunctive social (but not personal) portion size norms. Results suggest that being served (but not mere visual exposure to) smaller (relative to larger) portions changes perceived social norms about portion size and this may reduce future consumption of that food.

Portion size normality and additional within-meal food intake: two crossover laboratory experiments

Reducing food portion size could reduce energy intake. However, it is unclear at what point consumers respond to reductions by increasing intake of other foods. We predicted that a change in served portion size would only result in significant additional eating within the same meal if the resulting portion size was no longer visually perceived as 'normal'. Participants in two crossover experiments (Study 1: n 45; Study 2: n 37; adults, 51 % female) were served different-sized lunchtime portions on three occasions that were perceived by a previous sample of participants as 'large-normal', 'small-normal' and 'smaller than normal', respectively. Participants were able to serve themselves additional helpings of the same food (Study 1) or dessert items (Study 2). In Study 1 there was a small but significant increase in additional intake when participants were served the 'smaller than normal' compared with the 'small-normal' portion (m difference = 161 kJ, P = 0·002, d = 0·35), but there was no significant difference between the 'small-normal' and 'large-normal' conditions (m difference = 88 kJ, P = 0·08, d = 0·24). A similar pattern was observed in Study 2 (m difference = 149 kJ, P = 0·06, d = 0·18; m difference = 83 kJ, P = 0·26, d = 0·10). However, smaller portion sizes were each associated with a significant reduction in total meal intake. The findings provide preliminary evidence that reductions that result in portions appearing 'normal' in size may limit additional eating, but confirmatory research is needed.

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.

When a portion becomes a norm: Exposure to a smaller vs. larger portion of food affects later food intake

BACKGROUND

Portion sizes in the food environment may communicate information about what constitutes a 'normal' amount of food to eat. Here we examined whether mere visual exposure to a smaller vs. larger portion size of snack food affects perceptions of how much a 'normal' sized portion is and how much people choose to eat of that food in future.

METHODS

Under the guise of a study on taste preference and personality, 104 female participants were randomly allocated to be exposed to either a smaller or larger portion size of snack food. Twenty-four hours later participants freely selected a portion of the snack food to consume and reported on their perception of what constituted a normal sized portion of the snack food.

RESULTS

Participants that were exposed to a smaller, as opposed to larger portion size subsequently believed that a normal portion of the snack food was smaller in size. Exposure to the smaller as opposed to the larger portion size also resulted in participants consuming less snack food the next day.

CONCLUSIONS

Environmental exposure to smaller, as opposed to larger portion sizes of food may change perceptions of what constitutes a normal amount of food to eat and affect the amount of food people choose to eat in future.

Portion size and meal consumption in domesticated dogs: An experimental study

Increases in food portion sizes have been identified as a possible contributor to the increased prevalence of obesity in humans. However, little is known about the origin of behavioural tendencies to overeat from larger portion sizes or whether other non-human animals are affected by meal portion size. In the present experimental study, we examined the effect that larger portion sizes have on meal consumption among domesticated dogs (N = 32). Dogs were fed three meals that varied in size on different occasions (150%, 200% and 300% of usual portion size). A repeated measures design was used and food consumption was measured for each meal. Portion size positively affected food consumption, with dogs eating significantly more food as the portion size of meal increased. The effect of portion size on food consumption was also observed when the dogs that finished all available food were excluded from analyses, however not among dogs who did not finish any of the meals. We conclude that the influence larger portions have on food consumption observed in humans is also observed in domesticated dogs. However, it is unclear whether portion size directly biases the amount of food dogs choose to consume, as has been suggested in humans. Further research is now warranted to examine commonalities between human and non-human animal eating behaviour to understand shared behavioural tendencies and their origins.

Identifying Barriers to Reducing Portion Size: A Qualitative Focus Group Study of British Men and Women

Reducing portion size might reduce meal satisfaction, which could minimize adherence to portion size interventions. The present study sought to identify the perceived barriers for consumers to eat smaller portions. A secondary aim explored the relative contribution of enjoyment of taste and post-meal fullness as determinants of meal satisfaction. Focus groups (N = 42) evaluated consumers' feelings toward a small reduction in portion size. Thematic analysis of written free association tasks and open-ended group discussions revealed that most participants expected to feel hungry and unsatisfied, which motivated them to consume something else. However, others expected to feel comfortable, healthy, and virtuous. The acceptability of the reduced portion was also determined by meal characteristics (e.g., time and setting) and individual characteristics (e.g., predicted energy requirements). Compared to post-meal fullness, enjoyment of taste was perceived to be the more important determinant of meal satisfaction. In conclusion, interventions should present portion reduction as a marginal modification with little physiological consequence to energy reserves, while emphasizing the positive feelings (e.g., comfort, satisfaction, and self-worth) experienced after consuming a smaller portion. Additionally, focusing on taste enjoyment (rather than fullness) might be a useful strategy to maintain meal satisfaction despite a reduction in meal size.

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

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

Comparison between serving sizes of cakes and muffins sold in Australian supermarkets and coffee shop chains

AIM

Cakes and muffins are commonly consumed discretionary foods that have increased significantly in portion size over the past decades. The present study aimed to (i) investigate serving sizes and energy per serving of cakes and muffins sold in supermarkets and coffee chains, (ii) compare to standard discretionary serves and (iii) propose feasible and appropriate serving size recommendations.

METHODS

Serving sizes and energy content of cakes and muffins were collected from four major Australian supermarkets (n = 219) and eight coffee chains (n = 248) between March and April 2017 and classified into eight categories and compared using Mann-Whitney tests. Median energy per serving of cakes and muffins from supermarkets and coffee chains were compared to the Australian Dietary Guidelines standard serve of 600 kJ for discretionary food.

RESULTS

The median serving size of cakes and muffins from supermarkets, 58 g (interquartile range, IQR: 47-83) and their energy content, 915 kJ (IQR: 745-1243) were significantly smaller compared with coffee chain equivalents, 148 g (IQR: 115-171, P < 0.001) and 1805 kJ (IQR: 1436-2004, P < 0.001), respectively. The majority of cakes and muffins exceeded the Australian Dietary Guidelines standard serve (78% from supermarkets and 99% from coffee chains).

CONCLUSIONS

The larger servings of cakes and muffins sold in coffee chains contain nearly double the energy content of smaller servings sold in supermarkets. We recommend reference serving sizes for industry and food retail are set for this category, in combination with consumer education to guide consumers to select appropriate portion sizes.

Portion size has sustained effects over 5 days in preschool children: a randomized trial

BACKGROUND

Although short-term studies have found that serving larger portions of food increases intake in preschool children, it is unknown whether this portion size effect persists over a longer period or whether energy intake is moderated through self-regulation.

OBJECTIVES

We tested whether the portion size effect is sustained in preschool children across 5 consecutive days, a period thought to be sufficient for regulatory systems to respond to the overconsumption of energy.

METHODS

With the use of a crossover design, over 2 periods we served the same 5 daily menus to 46 children aged 3-5 y in their childcare centers. In 1 period, all foods and milk were served in baseline portions, and in the other period, all portions were increased by 50%. The served items were weighed to determine intake.

RESULTS

Increasing the portion size of all foods and milk by 50% increased daily consumption: weighed intake increased by a mean ± SEM of 143 ± 21 g/d (16%) and energy intake increased by 167 ± 22 kcal/d (18%; both P < 0.0001). The trajectories of intake by weight and energy across the 5-day period were linear and the slopes did not differ between portion conditions (both P > 0.13), indicating that there were sustained increases in intake from larger portions without compensatory changes over time. Children differed in their response to increased portions: those with higher weight status, lower ratings for satiety responsiveness, or higher ratings for food responsiveness had greater increases in intake from larger portions (all P < 0.03).

CONCLUSIONS

This demonstration that preschool children failed to adjust their intake during prolonged exposure to larger portions challenges the suggestion that their self-regulatory behavior is sufficient to counter perturbations in energy intake. Furthermore, overconsumption from large portions may play a role in the development of overweight and obesity, as the magnitude of the effect was greater in children of higher weight status. This trial was registered at www.clinicaltrials.gov as NCT02963987.

Potential moderators of the portion size effect

AIM

The robust effect of portion size on intake has led to growing interest in why individuals consume more food when served larger portions. A number of explanations have been proposed, and this review aims to provide insight into potential underlying factors by summarizing recent studies testing moderators of the portion size effect.

SUMMARY OF FINDINGS

Provision of portion size information, such as through labeling or training in portion control, failed to attenuate food intake in response to increasing meal size. This indicates that a lack of knowledge about appropriate portions may not be sufficient to explain the portion size effect. In contrast, there is evidence for a role of decision making in the response to large portions, with value being one consideration of importance. The portion size effect may be more closely related to the inherent value of food than monetary value, since provision of the opportunity to take away uneaten food after a meal, which can reduce food waste, attenuated the portion size effect but variations in pricing did not. A number of studies also support an influence of orosensory processing on the portion size effect; large portions have been shown to relate to increased bite size and faster eating rate. Reduced oral processing time when consuming large portions could contribute to the effect by delaying sensory-specific satiety. Findings from a recent study supported this by demonstrating that sensory-specific satiety did not differ between larger and smaller portions despite substantial differences in intake.

CONCLUSIONS

A number of moderators of the portion size effect have been identified, including factors related to the environment, the food, and the individual. It is likely that multiple variables contribute to the response to large portions. Future research should aim to determine the relative contribution of explanatory variables across different contexts and individuals.

(Over)eating out at major UK restaurant chains: observational study of energy content of main meals

OBJECTIVES

To examine the energy content of main meals served in major UK restaurant chains and compare the energy content of meals in fast food and "full service" restaurant chains.

DESIGN

Observational study.

SETTING

Menu and nutritional information provided by major UK restaurant chains.

MAIN OUTCOME MEASURES

Mean energy content of meals, proportion of meals meeting public health recommendations for energy consumption (≤600 kcal), and proportion of meals with excessive energy content (≥1000 kcal).

RESULTS

Main meals from 27 restaurant chains (21 full service; 6 fast food) were sampled. The mean energy content of all eligible restaurant meals (13 396 in total) was 977 (95% confidence interval 973 to 983) kcal. The percentage of all meals that met public health recommendations for energy content was low (9%; n=1226) and smaller than the percentage of meals with an excessive energy content (47%; 6251). Compared with fast food restaurants, full service restaurants offered significantly more excessively calorific main meals, fewer main meals meeting public health recommendations, and on average 268 (103 to 433) kcal more in main meals.

CONCLUSIONS

The energy content of a large number of main meals in major UK restaurant chains is excessive, and only a minority meet public health recommendations. Although the poor nutritional quality of fast food meals has been well documented, the energy content of full service restaurant meals in the UK tends to be higher and is a cause for concern.

REGISTRATION

Study protocol and analysis strategy pre-registered on Open Science Framework (https://osf.io/w5h8q/).

The Feasibility and Acceptability of Two Methods of Snack Portion Control in United Kingdom (UK) Preschool Children: Reduction and Replacement

Large portions of high energy dense (HED) snacks are offered to children from a young age and are pervasive in our food environment. This study aimed to explore the feasibility, acceptability, and preliminary efficacy of two strategies of snack portion control: reduction and replacement. Forty-six mother-child dyads aged 22⁻56 months (36.6 ± 9.5 m, 48% female) completed a three-week intervention. In week 1 (baseline) no changes were made to the child's diet; week 2 (acclimation) children received a standardised selection of HED snacks, and in week 3 (intervention) participants were randomly assigned to snack replacement (n = 24) or snack reduction (n = 22). Snack replacement involved swapping HED snacks for fruits and vegetables, whilst snack reduction involved reducing the size of HED snacks by 50%. Food and energy intake were measured using a weighed food diary for four consecutive days. Snack replacement resulted in more positive changes to children's diets; vegetable intake increased (p < 0.01), and total daily energy intake decreased when compared to snack reduction (p < 0.05). Mothers expressed a more favourable attitude to snack replacement, although snack reduction was also well received by mothers. Despite increased preliminary efficacy of snack replacement on dietary intake, both strategies were feasible and acceptable. The current pilot study provides the necessary information to inform the design of future interventions.