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Objective Reducing meat consumption would have substantial benefits both in terms of health and environmental impact, but meat options may be more attractive to customers than meat-free options. This study tested this by presenting UK adults (n = 540) with a series of pictures showing two meal options and asking them to select which they would prefer to eat right now. They completed this task for every possible pair from a pool of six comparator meat-based options and six target options (66 pairs). Participants all saw identical comparator options, and were randomised to see the same pictures of target options but with descriptions that suggested they were either meat-based or vegetarian. Results Selections were used to rank the options for each individual from 1 (most-selected) to 12 (least-selected). Vegetarian target options were ranked worse [by 1.23 places (95% CI: 1.02, 1.44)] than meat target options. Higher self-reported consumption of meat predicted worse mean rankings of target options when these were vegetarian, but not when target options were meat-based. This suggests meat options are preferred to equivalent vegetarian options and may be more likely to be selected. This has implications for interventions aiming to reduce meat consumption to make diets healthier and more sustainable.

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 p 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 p 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).

BackgroundReducing alcohol consumption across populations would prevent many non-communicable diseases. Large packages increase food and non-alcoholic drink consumption and large glasses increase wine consumption. Smaller bottles may reduce alcohol consumption but their impact is uncertain. This study aims to (i) explore the feasibility and acceptability of conducting a large-scale randomised study to assess the impact of bottle size on in-home wine consumption and (ii) estimate the effect size and variance of the intervention on consumption to inform the design of future studies.MethodsCross-over randomised study in which 16 households in Cambridge, England, consuming at least two 750-ml bottles of wine each week, received a pre-set volume of wine biweekly for 4 weeks, in 750-ml and 375-ml bottles, in random order. Consumption was assessed by recording the number of empty and partially full bottles at the end of each biweekly period. At the end of the study, household representatives were interviewed about their experiences of participating in the study.ResultsThe study procedures proved feasible. Comparable to similar trials, 14% of identified eligible households (18/125) consented to participate in the study. Attrition between consent and study completion was 11% (2/18) and 0% between study periods and 13% of households (2/16) correctly identified the study aim. The study procedures were considered acceptable. After adjusting for guest and out-of-home consumption, the difference in consumption between the 750-ml (3385.2 ml; SD = 1698.5) and 375-ml bottles (3376.7 ml; SD = 1719.0) was 8.4 ml (SD = 1235.4; 95%CI − 596.9, 613.8). Results suggest a possible order effect, with households receiving the 375-ml bottles first consuming more wine out of the 750-ml bottles and vice versa. This might also reflect an increase in consumption with study duration. Households receiving the 375-ml bottles first (6315.9 ml; SD = 3293.5) also drank less wine overall than those receiving the 750-ml bottles first (7335.4 ml; SD = 3735.4).DiscussionThe findings support the feasibility and acceptability of running a large-scale randomised study to assess the impact of bottle size on in-home wine consumption. Due to the heterogeneous patterning of results, a future study will be powered using the variance observed in the current study to detect a meaningful reduction of 250 ml of wine when consumed from smaller compared with larger bottles.Trial registrationOpen Science Framework (OSF):rmk43; May 23, 2017.

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., James Reynolds and co-workers investigate the provision of smaller food portions and substitution of less calorific foods in workplace cafeterias., Author summary Why was this study done? Overconsumption of energy from food and drink contributes to the high and rising rates of obesity in many countries. Creating healthier food environments is the key to enabling healthier diets. There is insufficient real-world evidence on the best ways to improve food environments. What did the researchers do and find? Two interventions were evaluated: (i) availability: replacing some higher energy foods with lower energy foods; and (ii) size: reducing the portion size of some higher energy foods. We carried out a randomised stepped-wedge trial in 19 cafeterias spanning 25 weeks. The availability reduced energy purchased by 4.8%, and the availability plus size intervention reduced energy purchased by 11.5%. What do these findings mean? Replacing some higher energy foods in cafeterias with lower energy options and reducing the portion size of some higher energy foods both appear to be effective strategies for reducing energy purchased in worksite cafeterias. These interventions can contribute to broader strategies to reduce energy intake out of the home, as part of national and international efforts to tackle overweight and obesity.

Background Altering the availability of healthier or less-healthy products may increase healthier purchases, but evidence is currently limited. The current study aimed to investigate the impact of altering the absolute-and-relative availability of healthier and less-healthy products – i.e. simultaneously altering the number of options available and the proportion of healthier options – in hospital vending machines. Methods An adapted multiple treatment reversal design was used, altering products available in ten vending machines serving snack foods and/or cold drinks in one English hospital. Machines were randomised to one of two sequences for the seven 4-week study periods: ABCADEA or ADEABCA. In Condition A (study periods 1, 4 and 7) the proportions of healthier products were standardised across all machines, so that 25% of all snack slots and 75% of drink slots were healthier. In Condition B, 20% of vending machine slots were emptied by removing less-healthy products. In Condition C, the empty slots created in Condition B were filled with healthier products. Conditions D and E were operationalised in the same way as B and C, except healthier products were removed in D, and then less-healthy products added in E. Sales data were obtained from machine restocking records. Separate linear mixed models were conducted to examine the impact of altering availability on energy purchased (kcal) from (i) snacks or (ii) drinks each week, with random effects for vending machine. Results The energy purchased from drinks was reduced when the number of slots containing less-healthy drinks was decreased, compared to standardised levels (− 52.6%; 95%CI: − 69.3,-26.9). Findings were inconclusive for energy purchased from snacks when less-healthy snack slots were reduced (− 17.2%; 95%CI: − 47.4,30.5). Results for altering the number of slots for healthier drinks or snacks were similarly inconclusive, with no statistically significant impact on energy purchased. Conclusions Reducing the availability of less-healthy drinks could reduce the energy purchased from drinks in vending machines. Further studies are needed to establish whether any effects might be smaller for snacks, or found with higher baseline proportions of healthier options.

Background Calorie labelling may help to reduce energy consumption, but few well-controlled experimental studies have been conducted in real world settings. In a previous randomised controlled pilot trial we did not observe an effect of calorie labelling on energy purchased in worksite cafeterias. In the present study we sought to enhance the effect by making the labels more prominent, and to address the operational challenges reported previously by worksites. Methods Three worksite cafeterias were randomised in a stepped wedge design to start the intervention at one of three fortnightly periods between March and July 2018. The intervention comprised introducing prominent calorie labelling for all cafeteria products for which calorie information was available (on average 87% of products offered across the three sites were labelled). Calorie content was displayed in bold capitalised Verdana typeface with a minimum font size of 14 e.g. 120 CALORIES. Feasibility and acceptability were assessed using post-intervention surveys with cafeteria patrons and semi-structured interviews with managers. Effectiveness was assessed using total daily energy (kcal) purchased from intervention items across the three sites, analysed using semi-parametric GAMLSS models. Results Recruitment and retention of worksite cafeterias proved feasible: all three randomised sites successfully completed the study. Post-intervention feedback suggested high levels of intervention acceptability: 87% of responding patrons wanted calorie labelling to remain in place. No effect of the intervention on daily energy purchased was observed: −0.6% (95%CI -2.5 to 1.2, p = .487). By-site analyses showed similar null effects at each of the three sites, all ps > .110. Conclusions There was no evidence that prominent calorie labelling changed daily energy purchased across three English-based worksite cafeterias. The intervention was feasible to implement and acceptable to patrons and managers.

Altering the availability of products (e.g. food, alcohol or tobacco products) is one potential intervention to change behaviours to help reduce preventable premature deaths worldwide. However, research on these interventions lacks consistent conceptualisation, hindering clear reporting and cumulative synthesis. This paper proposes a conceptual framework – categorising intervention types and summarising constituent components – with which interventions can be reliably described and evidence synthesised. Three principal distinctions are proposed: interventions altering: (i) Absolute Availability (changing the overall number of options, while keeping the proportions comprised by any subsets of options constant); (ii) Relative Availability (changing the proportion comprised by a subset of options, yet keeping the overall number of options constant); (iii) Absolute and Relative Availability (changing both the overall number of options and the proportions comprised by subsets of options). These are subdivided into those targeting (a) a product or (b) a category of products. Mechanisms that might underlie each of these intervention types are discussed, and implications for future research highlighted. The proposed framework aims to facilitate study of a set of interventions that could contribute significantly to healthier behaviour across populations.

Sugar-sweetened beverage (SSB) consumption increases obesity risk and is linked to adverse health consequences. Large packages increase food consumption, but most evidence comes from studies comparing larger with standard packages, resulting in uncertainty regarding the impact of smaller packages. There is also little research on beverages. This qualitative study explores the experiences of consuming cola from smaller compared with larger bottles, to inform intervention strategies. Sixteen households in Cambridge, England, participating in a feasibility study assessing the impact of bottle size on in-home SSB consumption, received a set amount of cola each week for four weeks in one of four bottle sizes: 1500 ml, 1000 ml, 500 ml, or 250 ml, in random order. At the study end, household representatives were interviewed about their experiences of using each bottle, including perceptions of i) consumption level; ii) consumption-related behaviours; and iii) factors affecting consumption. Interviews were semi-structured and data analysed using the Framework approach. The present analysis focuses specifically on experiences relating to use of the smaller bottles. The smallest bottles were described as increasing drinking occasion frequency and encouraging consumption of numerous bottles in succession. Factors described as facilitating their consumption were: i) convenience and portability; ii) greater numbers of bottles available, which hindered consumption monitoring and control; iii) perceived insufficient quantity per bottle; and iv) positive attitudes. In a minority of cases the smallest bottles were perceived to have reduced consumption, but this was related to practical issues with the bottles that resulted in dislike. The perception of greater consumption and qualitative reports of drinking habits associated with the smallest bottles raise the possibility that the ‘portion size effect’ has a lower threshold, beyond which smaller portions and packages may increase consumption. This reinforces the need for empirical evidence to assess the in-home impact of smaller bottles on SSB consumption.

Aims To evaluate the impact of the 2011 Scottish ban on multi-buy promotions of alcohol in retail stores. Design and setting Difference-in-differences analysis was used to estimate the impact of the ban on the volume of alcohol purchased by Scottish households, compared with those in England and Wales, between January 2010 and June 2012. Participants A total of 22 356 households in Scotland, England and Wales. Measurements Records of alcohol purchasing from each of four categories (beer and cider, wine, spirits and flavoured alcoholic beverages), as well as total volume of pure alcohol purchased. Findings Controlling for general time trends and household heterogeneity, there was no significant effect of the multi-buy ban in Scotland on volume of alcohol purchased either for the whole population or for individual socio-economic groups. There was also no significant effect on those who were large pre-ban purchasers of alcohol. Most multi-buys were for beer and cider or for wine. The frequency of shopping trips involving beer and cider purchases increased by 9.2% following the ban (P

Wine glass size may influence perceived volume and subsequently purchasing and consumption. Using a larger glass to serve the same portions of wine was found to increase wine sales by 9.4% (95% CI 1.9, 17.5) in a recent study conducted in one bar. The current study aimed to replicate this previous work in two other bars using a wider range of glass sizes. To match the previous study, a repeated multiple treatment reversal design, during which wine was served in glasses of the same design but different sizes, was used. The study was conducted in two bars in Cambridge, England, using glass sizes of 300, 370, 510 ml (Bar 1) and 300 and 510 ml (Bar 2). Customers purchased their choice of a 750 ml bottle, or standard UK measures of 125, 175 or 250 ml of wine, each of which was served with the same glass.Bar 1: Daily wine volume (ml) purchased was 10.5% (95% CI 1.0, 20.9) higher when sold in 510 ml compared to 370 ml glasses; but sales were not significantly different with 300 ml vs. 370 ml glasses (6.5%, 95% CI −5.2, 19.6) [corrected]. Bar 2 Findings were inconclusive as to whether daily wine purchased differed when using 510 ml versus 300 ml glasses (-1.1%, 95% CI -12.6, 11.9). These results provide a partial replication of previous work showing that introducing larger glasses (without manipulating portion size) increases purchasing. Understanding the mechanisms by which wine glass size influences consumption may elucidate when the effect can be expected and when not. Trial registration This study is a replication study, based on the procedure set out in the trial registration for the study that it attempts to replicate (ISRCTN registry: ISRCTN12018175).

Objective Wine glass size may influence perceived volume and subsequently purchasing and consumption. Using a larger glass to serve the same portions of wine was found to increase wine sales by 9.4% (95% CI 1.9, 17.5) in a recent study conducted in one bar. The current study aimed to replicate this previous work in two other bars using a wider range of glass sizes. To match the previous study, a repeated multiple treatment reversal design, during which wine was served in glasses of the same design but different sizes, was used. The study was conducted in two bars in Cambridge, England, using glass sizes of 300, 370, 510 ml (Bar 1) and 300 and 510 ml (Bar 2). Customers purchased their choice of a 750 ml bottle, or standard UK measures of 125, 175 or 250 ml of wine, each of which was served with the same glass. Results Bar 1 Daily wine volume (ml) purchased was 10.5% (95% CI 1.0, 20.9) higher when sold in 510 ml compared to 370 ml glasses; but sales were not significantly different with 300 ml vs. 370 ml glasses (6.5%, 95% CI −5.2, 19.6). Bar 2 Findings were inconclusive as to whether daily wine purchased differed when using 510 ml versus 300 ml glasses (−1.1%, 95% CI −12.6, 11.9). These results provide a partial replication of previous work showing that introducing larger glasses (without manipulating portion size) increases purchasing. Understanding the mechanisms by which wine glass size influences consumption may elucidate when the effect can be expected and when not. Trial registration This study is a replication study, based on the procedure set out in the trial registration for the study that it attempts to replicate (ISRCTN registry: ISRCTN12018175)

Background: An estimated one third of energy is consumed in the workplace. The workplace is therefore an important context in which to reduce energy consumption to tackle the high rates of overweight and obesity in the general population. Altering environmental cues for food selection and consumption—physical microenvironment or 'choice architecture' interventions—has the potential to reduce energy intake. The first aim of this pilot trial is to estimate the potential impact upon energy purchased of three such environmental cues (size of portions, packages and tableware; availability of healthier vs. less healthy options; and energy labelling) in workplace cafeterias. A second aim of this pilot trial is to examine the feasibility of recruiting eligible worksites, and identify barriers to the feasibility and acceptability of implementing the interventions in preparation for a larger trial. Methods: Eighteen worksite cafeterias in England will be assigned to one of three intervention groups to assess the impact on energy purchased of altering (a) portion, package and tableware size (n = 6); (b) availability of healthier options (n = 6); and (c) energy (calorie) labelling (n = 6). Using a stepped wedge design, sites will implement allocated interventions at different time periods, as randomised. Discussion: This pilot trial will examine the feasibility of recruiting eligible worksites, and the feasibility and acceptability of implementing the interventions in preparation for a larger trial. In addition, a series of linear mixed models will be used to estimate the impact of each intervention on total energy (calories) purchased per time frame of analysis (daily or weekly) controlling for the total sales/transactions adjusted for calendar time and with random effects for worksite. These analyses will allow an estimate of an effect size of each of the three proposed interventions, which will form the basis of the sample size calculations necessary for a larger trial. Trial registration: ISRCTN52923504

Public acceptability influences policy action, but the most acceptable policies are not always the most effective. This discrete choice experiment provides a novel investigation of the acceptability of different interventions to reduce alcohol consumption and the effect of information on expected effectiveness, using a UK general population sample of 1202 adults. Policy options included high, medium and low intensity versions of: Minimum Unit Pricing (MUP) for alcohol; reducing numbers of alcohol retail outlets; and regulating alcohol advertising. Outcomes of interventions were predicted for: alcohol-related crimes; alcohol-related hospital admissions; and heavy drinkers. First, the models obtained were used to predict preferences if expected outcomes of interventions were not taken into account. In such models around half of participants or more were predicted to prefer the status quo over implementing outlet reductions or higher intensity MUP. Second, preferences were predicted when information on expected outcomes was considered, with most participants now choosing any given intervention over the status quo. Acceptability of MUP interventions increased by the greatest extent: from 43% to 63% preferring MUP of £1 to the status quo. Respondents' own drinking behaviour also influenced preferences, with around 90% of non-drinkers being predicted to choose all interventions over the status quo, and with more moderate than heavy drinkers favouring a given policy over the status quo. Importantly, the study findings suggest public acceptability of alcohol interventions is dependent on both the nature of the policy and its expected effectiveness. Policy-makers struggling to mobilise support for hitherto unpopular but promising policies should consider giving greater prominence to their expected outcomes., Highlights • Novel UK-representative study predicting the acceptability of alcohol interventions. • Acceptability varied by policy: regulating advertising was the most popular option. • Acceptability increased for all policies with information on expected effectiveness. • Information on expected effectiveness changed the order of preference for policies.

In-store product placement is perceived to be a factor underpinning impulsive food purchasing but empirical evidence is limited. In this study we present the first in-depth estimate of the effect of end-of-aisle display on sales, focussing on alcohol. Data on store layout and product-level sales during 2010–11 were obtained for one UK grocery store, comprising detailed information on shelf space, price, price promotion and weekly sales volume in three alcohol categories (beer, wine, spirits) and three non-alcohol categories (carbonated drinks, coffee, tea). Multiple regression techniques were used to estimate the effect of end-of-aisle display on sales, controlling for price, price promotion, and the number of display locations for each product. End-of-aisle display increased sales volumes in all three alcohol categories: by 23.2% (p = 0.005) for beer, 33.6% (p, Highlights • An estimated 30% of supermarket sales come from aisle-ends, providing an impetus to evaluate the influence of such locations. • This novel analysis within one UK store suggested that placing beverages in end-of-aisle locations uplifts sales sharply. • This sales uplift was larger for non-alcoholic beverages (by 52–114%) than for alcoholic beverages (by 23–46%). • Restricting aisle-end displays of alcohol or sugar-sweetened beverages may be as effective as some pricing interventions. • Although currently limited to product-level effects, this initial evidence highlights the influence of aisle-end displays.

BACKGROUND: Intake of free sugars in the population exceeds recommendations, with the largest source in the diet being sugar-sweetened beverages (SSBs). SSB consumption is linked to adverse health consequences and contributes to health inequalities, given greater consumption amongst the most deprived. One possible intervention is to reduce the available sizes of SSB packaging but there is an absence of evidence that this would reduce consumption. Based on evidence from studies targeting food consumption that people consume less when exposed to smaller package sizes, we hypothesise that presenting SSBs in smaller containers reduces consumption. We are planning a crossover randomised controlled trial to assess the impact of presenting a fixed volume of SSB in different bottle sizes on consumption at home. To reduce the uncertainties related to this trial, we propose a preliminary study to assess the feasibility and acceptability of the recruitment, allocation, measurement, retention and intervention procedures. METHODS/DESIGN: Households which purchase at least 2 l of regular cola drinks per week and live in Cambridgeshire, UK will have a set amount of a cola SSB (based on their typical weekly purchasing of cola) delivered to their homes each week by the research team. This total amount of cola will be packaged into bottles of one of four sizes: (i) 1500 ml, (ii) 1000 ml, (iii) 500 ml or (iv) 250 ml. A crossover design will be used in which households will each receive all four of the week-long interventions (the four different bottle sizes) over time, randomised in their order of presentation. Approximately 100 eligible households will be approached to assess the proportion interested in actively participating in the study. Of those interested, 16 will be invited to continue participation. DISCUSSION: The findings will inform the procedures for a crossover randomised controlled trial assessing the impact of presenting a fixed volume of SSB in different bottle sizes on consumption at home. The findings from such a trial are expected to provide the best estimate to date of the effect of container size on beverage consumption and inform ongoing scientific and policy discussions about the effectiveness of this intervention at reducing population intake of free sugars in beverages. TRIAL REGISTRATION: ISRCTN14964130.

Background Governments sometimes face important decisions in the absence of direct evidence. In these cases, expert elicitation methods can be used to quantify uncertainty. We report the results of an expert elicitation study regarding the likely impact on smoking rates in adults and children of plain packaging of tobacco products. Methods Thirty-three tobacco control experts were recruited from the UK (n = 14), Australasia (n = 12) and North America (n = 7). Experts’ estimates were individually elicited via telephone interviews, and then linearly pooled. Elicited estimates consisted of (1) the most likely, (2) the highest possible, and (3) the lowest possible value for the percentage of (a) adult smokers and (b) children trying smoking, two years after the introduction of plain packaging (all other things being constant) in a target country in the expert’s region of residence. Results The median estimate for the impact on adult smoking prevalence was a 1 percentage point decline (99% range 2.25 to 0), and for the percentage of children trying smoking was a 3 percentage point decline (99% range 6.1 to 0), the latter estimated impact being larger than the former (P 2: Adults: 0; Children: 0) but there was considerable variability between experts’ estimates within regions (I2: Adults: 0.91; Children: 0.89). Conclusions In the absence of direct evidence for the impact of introducing plain packaging on smoking rates in adults and children, this study shows that tobacco control experts felt the most likely outcomes would be a reduction in smoking prevalence in adults, and a greater reduction in the numbers of children trying smoking, although there was substantial variability in the estimated size of these impacts. No experts judged an increase in smoking as a likely outcome.

Background Consumption of sugars-sweetened beverages (SSB) increases energy intake and the risk of obesity. Large packages increase consumption of food, implying that smaller bottle sizes may help curb SSB consumption, but there is a lack of relevant evidence relating to these products. This study explores the feasibility and acceptability of conducting a randomised controlled trial to assess the impact of different bottle sizes on SSB consumption at home. Methods Households in Cambridge, England, which purchased at least 2 l of regular cola drinks per week, received a set amount of cola each week for four weeks, in bottles of one of four sizes (1500 ml, 1000 ml, 500 ml, or 250 ml) in random order. The total volume received consisted of a modest excess of households’ typical weekly purchasing, but was further increased for half the study households to avoid ceiling effects. Consumption was measured by recording the number of empty bottles at the end of each week. Eligible households were invited to complete a run-in period to assess levels of active participation. Results Thirty-seven of 111 eligible households with an interest in the study completed the run-in period. The study procedures proved feasible. The target for recruitment (n = 16 households) was exceeded. Measuring consumption was feasible: over three quarters (n = 30/37) of households returned all bottles on the majority (n = 88/101) of the study weeks completed across households. The validity of this measure was compromised by guests from outside the household who drank the study cola (n = 18/37 households on 48/101 study weeks) and consumption of the study cola outside the home. Supplying enhanced volumes of cola to nine households was associated with higher consumption (11,592 ml vs 7869 ml). The intervention and study procedures were considered acceptable. Thirteen households correctly identified the study aims. Conclusion The findings support the feasibility and acceptability of running a randomised controlled trial to assess the impact of presenting a fixed volume of SSB in different bottle sizes on in-home consumption. However, methods that avoid consumption being influenced by the amount of cola supplied weekly by the study and that capture out of home consumption are needed before conducting a randomised controlled trial. Trial registration ISRCTN14964130; Registered on 18th May, 2015.

BACKGROUND: Wine glass size can influence both perceptions of portion size and the amount poured, but its impact upon purchasing and consumption is unknown. This study aimed to examine the impact of wine glass size on wine sales for on-site consumption, keeping portion size constant.METHODS: In one establishment (with separate bar and restaurant areas) in Cambridge, England, wine glass size (Standard; Larger; Smaller) was changed over eight fortnightly periods. The bar and restaurant differ in wine sales by the glass vs. by the bottle (93 % vs. 63 % by the glass respectively).RESULTS: Daily wine volume purchased was 9.4 % (95 % CI: 1.9, 17.5) higher when sold in larger compared to standard-sized glasses. This effect seemed principally driven by sales in the bar area (bar: 14.4 % [3.3, 26.7]; restaurant: 8.2 % [-2.5, 20.1]). Findings were inconclusive as to whether sales were different with smaller vs. standard-sized glasses.CONCLUSIONS: The size of glasses in which wine is sold, keeping the portion size constant, can affect consumption, with larger glasses increasing consumption. The hypothesised mechanisms for these differential effects need to be tested in a replication study. If replicated, policy implications could include considering glass size amongst alcohol licensing requirements.TRIAL REGISTRATION: ISRCTN registry: ISRCTN12018175 . Registered 12(th) May 2015.