No Impact of Calorie or Unit Information on Ad Libitum Alcohol Consumption

Two online randomised controlled trials examining effects of alcohol calorie labelling on hypothetical ordering of calories from alcohol and food

BACKGROUND

Providing calorie information for alcoholic beverages is a potential public-health intervention which may serve to reduce alcohol use but also prevalence of overweight/obesity. Equivocal evidence has been found for the effectiveness of alcohol calorie information at reducing drinking intentions as well as purchasing and consumption. However, the extent at which calorie information 'on-trade' will impact consumer behaviour for both alcohol and food consumption has not been investigated.

AIMS

(1) To examine the presence of alcohol calorie labelling for hypothetical purchasing of alcohol and food in typical UK restaurant scenarios. (2) To determine the characteristics of individuals who will be likely to choose to view alcohol calorie labels.

METHODS

Two online randomised control trials using a hypothetical menu selection. In experiment one (N = 325) participants were randomised to the presence or absence of alcohol calorie labels. In experiment two (N = 1081) individuals were randomised to alcohol calorie labels absent or the choice to view alcohol calorie labels. The primary outcome for each study was calories ordered from alcoholic beverages.

RESULTS

There was no evidence that the presence of alcohol calorie information on restaurant menus impacted the number of calories ordered from alcoholic beverages or from food and soft drinks. Younger individuals and individuals who exhibit greater motives for good health were more likely to choose to view alcohol calorie labels.

CONCLUSIONS

In two online, hypothetical experiments there is no evidence for alcohol calorie labelling impacting consumer decisions to order alcohol or food. Given the choice, a self-selecting group of individuals who are more motivated by health concerns will view alcohol calorie labels, and in turn may be less likely to order alcohol.

Impact of health warning labels and calorie labels on selection and purchasing of alcoholic and non-alcoholic drinks: A randomized controlled trial

AIMS

To estimate the impact on selection and actual purchasing of (a) health warning labels (text-only and image-and-text) on alcoholic drinks and (b) calorie labels on alcoholic and non-alcoholic drinks.

DESIGN

Parallel-groups randomised controlled trial.

SETTING

Drinks were selected in a simulated online supermarket, before being purchased in an actual online supermarket.

PARTICIPANTS

Adults in England and Wales who regularly consumed and purchased beer or wine online (n = 651). Six hundred and eight participants completed the study and were included in the primary analysis.

INTERVENTIONS

Participants were randomized to one of six groups in a between-subjects three [health warning labels (HWLs) (i): image-and-text HWL; (ii) text-only HWL; (iii) no HWL] × 2 (calorie labels: present versus absent) factorial design (n per group 103-113).

MEASUREMENTS

The primary outcome measure was the number of alcohol units selected (with intention to purchase); secondary outcomes included alcohol units purchased and calories selected and purchased. There was no time limit for selection. For purchasing, participants were directed to purchase their drinks immediately (although they were allowed up to 2 weeks to do so).

FINDINGS

There was no evidence of main effects for either (a) HWLs or (b) calorie labels on the number of alcohol units selected (HWLs: F(2,599)  = 0.406, P = 0.666; calorie labels: F(1,599)  = 0.002, P = 0.961). There was also no evidence of an interaction between HWLs and calorie labels, and no evidence of an overall difference on any secondary outcomes. In pre-specified subgroup analyses comparing the 'calorie label only' group (n = 101) with the 'no label' group (n = 104) there was no evidence that calorie labels reduced the number of calories selected (unadjusted means: 1913 calories versus 2203, P = 0.643). Among the 75% of participants who went on to purchase drinks, those in the 'calorie label only' group (n = 74) purchased fewer calories than those in the 'no label' group (n = 79) (unadjusted means: 1532 versus 2090, P = 0.028).

CONCLUSIONS

There was no evidence that health warning labels reduced the number of alcohol units selected or purchased in an online retail context. There was some evidence suggesting that calorie labels on alcoholic and non-alcoholic drinks may reduce calories purchased from both types of drinks.

Socioeconomic position and the effect of energy labelling on consumer behaviour: a systematic review and meta-analysis

BACKGROUND

There are well documented socioeconomic disparities in diet quality and obesity. Menu energy labelling is a public health policy designed to improve diet and reduce obesity. However, it is unclear whether the impact energy labelling has on consumer behaviour is socially equitable or differs based on socioeconomic position (SEP).

METHODS

Systematic review and meta-analysis of experimental (between-subjects) and pre-post implementation field studies examining the impact of menu energy labelling on energy content of food and/or drink selections in higher vs. lower SEP groups.

RESULTS

Seventeen studies were eligible for inclusion. Meta-analyses of 13 experimental studies that predominantly examined hypothetical food and drink choices showed that energy labelling tended to be associated with a small reduction in energy content of selections that did not differ based on participant SEP (X2(1) = 0.26, p = .610). Effect estimates for higher SEP SMD = 0.067 [95% CI: -0.092 to 0.226] and lower SEP SMD = 0.115 [95% CI: -0.006 to 0.237] were similar. A meta-analysis of 3 pre-post implementation studies of energy labelling in the real world showed that the effect energy labelling had on consumer behaviour did not significantly differ based on SEP (X2(1) = 0.22, p = .636). In higher SEP the effect was SMD = 0.032 [95% CI: -0.053 to 0.117] and in lower SEP the effect was SMD = -0.005 [95% CI: -0.051 to 0.041].

CONCLUSIONS

Overall there was no convincing evidence that the effect energy labelling has on consumer behaviour significantly differs based on SEP. Further research examining multiple indicators of SEP and quantifying the long-term effects of energy labelling on consumer behaviour in real-world settings is now required.

REVIEW REGISTRATION

Registered on PROSPERO (CRD42022312532) and OSF ( https://doi.org/10.17605/OSF.IO/W7RDB ).

Calling time on responsible drinking: A qualitative study of perceptions of information on alcohol product labels

OBJECTIVES

This study aimed to explore (a) how people interpret responsible drinking messages on alcohol product labels, and (b) the acceptability of including health information on labels.

DESIGN

Qualitative interviews.

METHODS

Face-to-face semi-structured interviews were conducted with 20 people aged 21-63; 18 were classified risky drinkers using AUDIT-C. They were shown three sets of alcohol product labels: one including three responsible drinking messages (drink responsibly), one with three positively worded health messages (drinking less reduces risks) and one with three negatively worded health messages (drinking more increases risks). Health messages included information about cancer, liver and heart disease.

RESULTS

Thematic analysis identified three themes: ambiguity about alcohol labelling; identifying oneself as responsible; and acceptability of enhanced product labelling. Participants were critical of responsible drinking messages and wary of conflicting health information in the media. They positioned themselves as responsible, knowledgeable drinkers and distanced themselves from problem drinkers. They did not appear to support the inclusion of health information on labels; however, novel information was considered more impactful.

CONCLUSIONS

Responsible drinking messages were seen by our sample as an alcohol industry ploy. Although health messages about cancer were seen as potentially impactful, the ability of consumers to position themselves as unproblematic drinkers means that they may not see the information on the label as relevant to themselves. Understanding factors that increase the personal relevance of messages is needed, alongside an exploration of a wider range of methods for alcohol health communication.

“Doctor, Can I Drink an Alcohol-Free Beer?” Low-Alcohol and Alcohol-Free Drinks in People with Heavy Drinking or Alcohol Use Disorders: Systematic Review of the Literature

No- and low-alcohol drinks (NoLo) have been proposed as a potential way forward for the reduction in the alcohol burden of disease. So far, there is scarce synthesized evidence on the effects of these products on people with alcohol use disorder (AUD), or with a heavy or high-risk drinking pattern. The aim of the present study is to systematically review the evidence of the use of NoLo drinks in these populations. A total of 4045 records were screened and 10 studies were included in the review. Craving and desire to drink have been found to increase after the consumption of NoLo drinks in patients with AUD. The increase in craving correlates with the severity of alcohol dependence. In addition, in this population, alcohol-related cues might trigger physiological responses similar to those experienced when using alcohol. Furthermore, as mentioned, in some of the studies, consumption was shown to increase as the %ABV or verbal descriptors indicate lower alcohol. Last, according to the epidemiological data, heavy drinkers tend to use NoLo drinks on top of their usual alcohol consumption rather than as part of regular drinking patterns. Further studies should be conducted in people with AUD or people with a high-risk drinking pattern to provide new insight to guide clinicians, patients, and other stakeholders to make evidence-based informed decisions.

Energy labelling of alcoholic drinks: An important or inconsequential obesity policy?

Alcohol is calorie dense, but unlike food products, alcoholic drinks tend to be exempt from nutritional labelling laws that require energy content information to be displayed on packaging or at point of purchase. This review provides a perspective on the likely efficacy of alcoholic drink energy labelling as a public health policy to reduce obesity and discusses key questions to be addressed by future research. First, the contribution that alcohol makes to population level daily energy intake and obesity is outlined. Next, consumer need for alcohol energy labelling and the potential impacts on both consumer and industry behavior are discussed. Pathways and mechanisms by which energy labelling of alcoholic drinks could reduce obesity are considered, as well as possible unintended consequences of alcoholic drink energy labelling. Would widespread energy labelling of alcoholic drinks reduce obesity? The unclear effect that alcohol has on population level obesity, the modest contribution calories from alcohol make to daily energy intake and limited impact nutritional labelling policies tend to have on behavior, suggest alcohol energy labelling may have limited impact on population obesity prevalence as a standalone policy. However, there are a number of questions that will need to be answered by future research to make definitive conclusions on the potential for alcohol energy labelling policies to reduce obesity.

Nature and Potential Impact of Alcohol Health Warning Labels: A Scoping Review

Alcohol is toxic to human health. In addition to providing nutritional information, labels on alcohol products can be used to communicate warnings on alcohol-related harms to consumers. This scoping review examined novel or enhanced health warning labels to assess the current state of the research and the key studied characteristics of labels, along with their impact on the studied outcomes. Four databases (Web of Science, MEDLINE, PsycInfo, CINAHL) were searched between January 2010 and April 2021, and 27 papers were included in the review. The results found that most studies were undertaken in English-speaking populations, with the majority conducted online or in the laboratory setting as opposed to the real world. Seventy percent of the papers included at least one cancer-related message, in most instances referring either to cancer in general or to bowel cancer. Evidence from the only real-world long-term labelling intervention demonstrated that alcohol health warning labels designed to be visible and contain novel and specific information have the potential to be part of an effective labelling strategy. Alcohol health warning labels should be seen as tools to raise awareness on alcohol-related risks, being part of wider alcohol policy approaches.

Alcohol, calories, and obesity: A rapid systematic review and meta-analysis of consumer knowledge, support, and behavioral effects of energy labeling on alcoholic drinks

Mandatory energy (calorie) labeling of alcoholic drinks is a public health measure that could be used to address both alcohol consumption and obesity. We systematically reviewed studies examining consumer knowledge of the energy content of alcoholic drinks, public support for energy labeling, and the effect of energy labeling of alcoholic drinks on consumption behavior. Eighteen studies were included. Among studies examining consumer knowledge of the energy content of alcoholic drinks (N = 8) and support for energy labeling (N = 9), there was moderate evidence that people are unaware of the energy content of alcoholic drinks (pooled estimate: 74% [95% CI: 64%-82%] of participants inaccurate) and support energy labeling (pooled estimate: 64% [95% CI: 53%-73%] of participants support policy). Six studies examined the effect of energy labeling on consumption behavior. In these studies, there was no evidence of a beneficial effect of labeling on alcohol drinking-related outcome measures. However, the majority of studies were of low methodological quality and used proxy outcome measures, and none of the studies were conducted in real-world settings, resulting in a very low level of evidence and high degree of uncertainty. Further research is required to determine whether energy labeling of alcoholic drinks is likely to be an effective public health policy.

The effect of calorie and physical activity equivalent labelling of alcoholic drinks on drinking intentions in participants of higher and lower socioeconomic position: An experimental study

OBJECTIVES

The primary objective of the study was to examine the effect of calorie labelling and physical activity equivalence labelling of alcoholic drinks on drinking intentions in participants of lower and higher socioeconomic position (SEP).

METHODS

Participants (N = 1,084) of higher and lower SEP were recruited into an online study and randomized into one of three drink label conditions; Control (standard alcohol labelling), kcal labelling (standard labelling plus drink kilocalorie information), or kcal + PACE labelling (standard labelling and kilocalorie information, plus information on physical activity needed to compensate for drink calories). After viewing drink labels, participants reported alcohol drinking intentions. Participants also completed measures of alcoholic drink energy content estimation, beliefs about how calorie labelling would affect health behaviour and support for calorie labelling of alcoholic drinks.

RESULTS

kcal labelling (d = 0.31) and kcal + PACE labelling (d = 0.38) conditions had significantly lower drinking intentions compared to the control condition (ps < .001). There was no evidence that effect of labelling condition on drinking intentions was moderated by SEP. A subset of participants also reported that they believed calorie labelling would be likely to positively change their eating and exercise behaviour. Estimates of the energy content of alcoholic drinks tended to be inaccurate and the majority of participants supported the introduction of calorie labelling on alcoholic drinks.

CONCLUSIONS

Calorie labelling of alcoholic drinks resulted in small reductions to intended drinking and testing of the effect calorie labelling has on behaviour in real-world settings is now warranted.

Use as directed: do standard drink labels on alcohol containers help consumers drink (ir)responsibly? Real-world evidence from a quasi-experimental study in Yukon, Canada

INTRODUCTION AND AIMS

This paper examines the impact of an alcohol labelling intervention on recall of and support for standard drink (SD) labels, estimating the number of SDs in alcohol containers, and intended and unintended use of SD labels.

DESIGN AND METHODS

A quasi-experimental study was conducted in Canada where labels with a cancer warning, national drinking guidelines and SD information were applied to alcohol containers in the single liquor store in the intervention site, while usual labelling continued in the two liquor stores in the comparison site. Three waves of surveys were conducted in both sites before and at two time-points after the intervention with 2049 cohort participants. Generalised estimating equations were applied to estimate changes in all outcomes.

RESULTS

Participants in the intervention relative to the comparison site had greater odds of recalling [adjusted odds ratio (AOR) 5.69, 95% confidence interval (CI) 3.02, 10.71] and supporting SD labels (AOR 1.49, 95% CI 1.04, 2.12) and lower odds of reporting using SD labels to purchase high strength, low-cost alcohol (AOR 0.65, 95% CI 0.45, 0.93). Exposure to the labels had negligible effects on accurately estimating the number of SDs (AOR 1.06, 95% CI 0.59, 1.93) and using SD labels to drink within guidelines (AOR 1.04, 95% CI 0.75, 1.46).

DISCUSSION AND CONCLUSIONS

Evidence-informed labels increased support for and decreased unintended use of SD labels. Such labels can improve accuracy in estimating the number of SDs in alcohol containers and adherence to drinking guidelines.

The impact of promoting revised UK low-risk drinking guidelines on alcohol consumption: interrupted time series analysis

Background

The UK’s Chief Medical Officers revised the UK alcohol drinking guidelines in 2016 to ≤ 14 units per week (1 unit = 10 ml/8 g ethanol) for men and women. Previously, the guideline stated that men should not regularly consume more than 3–4 units per day and women should not regularly consume more than 2–3 units per day.

Objective

To evaluate the impact of promoting revised UK drinking guidelines on alcohol consumption.

Design

Interrupted time series analysis of observational data.

Setting

England, March 2014 to October 2017.

Participants

A total of 74,388 adults aged ≥ 16 years living in private households in England.

Interventions

Promotion of revised UK low-risk drinking guidelines.

Main outcome measures

Primary outcome – alcohol consumption measured by the Alcohol Use Disorders Identification Test – Consumption score. Secondary outcomes – average weekly consumption measured using graduated frequency, monthly alcohol consumption per capita adult (aged ≥ 16 years) derived from taxation data, monthly number of hospitalisations for alcohol poisoning (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision: T51.0, T51.1 and T51.9) and assault (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision: X85–Y09), and further measures of influences on behaviour change.

Data sources

The Alcohol Toolkit Study, a monthly cross-sectional survey and NHS Digital’s Hospital Episode Statistics.

Results

The revised drinking guidelines were not subject to large-scale promotion after the initial January 2016 announcement. An analysis of news reports found that mentions of the guidelines were mostly factual, and spiked during January 2016. In December 2015, the modelled average Alcohol Use Disorders Identification Test – Consumption score was 2.719 out of 12.000 and was decreasing by 0.003 each month. After the January 2016 announcement, Alcohol Use Disorders Identification Test – Consumption scores did not decrease significantly (β = 0.001, 95% confidence interval –0.079 to 0.099). However, the trend did change significantly such that scores subsequently increased by 0.005 each month (β = 0.008, 95% confidence interval 0.001 to 0.015). This change is equivalent to 0.5% of the population moving each month from drinking two or three times per week to drinking four or more times per week. Secondary analyses indicated that the change in trend began 6 months before the guideline announcement. The secondary outcome measures showed conflicting results, with no significant changes in consumption measures and no substantial changes in influences on behaviour change, but immediate reductions in hospitalisations of 7.3% for assaults and 15.4% for alcohol poisonings.

Limitations

The pre-intervention data collection period was only 2 months for influences on behaviour change and the graduated frequency measure. Our conclusions may be generalisable only to scenarios in which guidelines are announced but not promoted.

Conclusions

The announcement of revised UK low-risk drinking guidelines was not associated with clearly detectable changes in drinking behaviour. Observed reductions in alcohol-related hospitalisations are unlikely to be attributable to the revised guidelines. Promotion of the guidelines may have been prevented by opposition to the revised guidelines from the government's alcohol industry partners or because reduction in alcohol consumption was not a government priority or because practical obstacles prevented independent public health organisations from promoting the guidelines. Additional barriers to the effectiveness of guidelines may include low public understanding and a need for guidelines to engage more with how drinkers respond to and use them in practice.

Trial registration

Current Controlled Trials ISRCTN15189062.

Funding

This project was funded by the National Institute for Health Research (NIHR) Public Health Research programme and will be published in full in Public Health Research; Vol. 8, No. 14. See the NIHR Journals Library website for further project information.

Glass shape influences drinking behaviours in three laboratory experiments

Reducing consumption of drinks which contain high levels of sugar and/or alcohol may improve population health. There is increasing interest in health behaviour change approaches which work by changing cues in physical environments ("nudges"). Glassware represents a modifiable cue in the drinking environment that may influence how much we drink. Here, we report three laboratory experiments measuring consumption of soft drinks served in different glasses (straight-sided vs. outward-sloped), using distinct paradigms to measure drinking. In Study 1 (N = 200), though total drinking time was equivalent, participants consumed a soft drink with a more 'decelerated' trajectory from outward-sloped tumblers, characterised by a greater amount consumed in the first half of the drinking episode. In Study 2 (N = 72), during a bogus taste test, participants consumed less from straight-sided wine flutes than outward-sloped martini coupes. In Study 3 (N = 40), using facial electromyography to explore a potential mechanism for decreased consumption, straight-sided glasses elicited more 'pursed' lip embouchures, which may partly explain reduced consumption from these glasses. Using a combination of methods, including objective measures of volume drunk and physiological measures, these findings suggest that switching to straight-sided glasses may be one intervention contributing to the many needed to reduce consumption of health-harming drinks.

Perceptions of cannabis health information labels among people who use cannabis in the U.S. and Canada

BACKGROUND

The emergence of legal cannabis industries poses a new public health challenge. Health information labels are part of the public health strategy for tobacco and alcohol, but there is limited research on cannabis-related messaging. This study explored perceptions of cannabis health information labels among people who used cannabis in the last 12 months residing in the U.S. and Canada.

METHODS

The Global Drug Survey (GDS) is a large anonymous cross-sectional web-survey. In GDS2019, respondents were presented with six labels with cannabis-related health information (dependence; driving stoned; harms of smoking; harms to developing brain; lack of motivation; effects on memory), and asked if information was new, believed, would it change behavior, and about acceptability of having health labels on legal products. This paper includes 1,275 respondents from Canada and 2,224 from U.S. states where cannabis was legal at the time of the survey, and 5,230 from other U.S. states.

RESULTS

Few respondents said that the information was new (6.6-24.6%). Most said the information was believable (63.5-72.0%) other than for the dependence message (28.1% new, 56.8% believed), which was perceived to be the least likely to change behavior (10.2%). Driving stoned was the message perceived to be the most likely to change behavior (58.5%). Respondents living in Canada were less likely to say information was new and rated most messages more believable than those in the U.S. Respondents from legal U.S. states were less likely to say information was new compared to other states. Respondents who used cannabis daily rated acceptability of labels lower (27.8%) than those using 1-48 days (40.6%).

CONCLUSIONS

Novel, believable information may be more effective at changing behavior. Regular consumers may be less susceptible to messages. Information focusing on safer use strategies and benefits of reducing use may be more acceptable and should be assessed in future research.

Older Australians' perceptions of alcohol-related harms and low-risk alcohol guidelines

INTRODUCTION AND AIMS

Australia has an ageing population. Given the concomitant increase in the numbers and proportion of risky drinkers among older adults, research examining contributory factors is a priority. The current study examined older adults' estimates of the NHMRC low-risk drinking guidelines, consumption patterns and associated harms and self-identification of drinking type.

DESIGN AND METHODS

Data from respondents aged 50+ years (N = 11 886) in the 2016 National Drug Strategy Household Survey were subjected to secondary analyses. Estimates of low-risk drinking levels, perceived level of harm from current drinking, self-identification of drinking type and awareness of standard drinks and labelling were included. Data were examined for those aged 50-59 years and 60+.

RESULTS

Seventeen percent of older Australians drank at both long-term and short-term risk levels. Approximately 39% of males and 11% of females overestimated the long-term low-risk levels and 54% of males and 20% of females overestimated the short-term low-risk levels. Overestimation was highest among risky drinkers. Most older risky drinkers were aware of standard drinks and labelling; however, less than half perceived their drinking as harmful, instead identifying as social drinkers.

DISCUSSION AND CONCLUSIONS

Although substantial gaps are evident in older respondents' estimates of low-risk drinking, additional public awareness campaigns are likely to be of limited use. Older peoples' engagement with the public health system presents 'windows of opportunity' to provide targeted, age-appropriate harm reduction strategies. Appropriate intervention and policy responses are required to direct resources to this emerging area of concern.

A machine learning perspective on responsible gambling

Gamblers are frequently reminded to ‘gamble responsibly’. But these qualitative reminders come with no quantitative information for gamblers to judge relative product risk in skill-based gambling forms. By comparison, consumers purchasing alcohol are informed of product strength by alcohol by volume percentage (ABV%) or similar labels. This paper uses mixed logistic regression machine learning to uncover the potential variation in soccer betting outcomes. This paper uses data from four bet types and eight seasons of English Premier League soccer, ending in 2018. Outcomes across each bet type were compared using three betting strategies: the most-skilled prediction, a random strategy and the least-skilled prediction. There was a large spread in betting outcomes, with, for example, the per-bet average loss varying by a factor of 54 (from 1.1% to 58.9%). Gamblers’ losses were positively correlated with the observable betting odds across all bets, indicating that betting odds are one salient feature that could be used to inform gamblers about product risk. Such large differences in product risk are relevant to the promotion of responsible gambling.

Impact on product appeal of labeling wine and beer with (a) lower strength alcohol verbal descriptors and (b) percent alcohol by volume (%ABV): An experimental study

Lower strength alcohol products may help reduce alcohol consumption and associated harms. This study assessed the impact of labeling wine and beer with different verbal descriptors denoting lower strength, with and without percent alcohol by volume (%ABV), on product appeal and understanding of strength. Three thousand three hundred ninety adult survey-panel members were randomized to 1 of 18 groups with 1 of 3 levels of verbal descriptor (Low vs. Super Low vs. No verbal descriptor) and 6 levels of %ABV (5 levels varying for wine and beer, and no level given). Products with verbal descriptors denoting lower strength (Low and Super Low) had lower appeal than Regular strength products. Appeal decreased as %ABV decreased. Understanding of strength was generally high across the various drinks with majority of participants correctly identifying or erring on the side of caution when estimating the units and calories in a given drink, appropriateness for consumption by children, and drinking within the driving limit. We discuss the theoretical and policy implications of these findings for public health. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Impact of glass shape on time taken to drink a soft drink: A laboratory-based experiment

BACKGROUND

Glassware design may affect drinking behaviour for alcoholic beverages, with glass shape and size influencing drinking speed and amount consumed. Uncertainty remains both about the extent to which these effects are restricted to alcohol and the underlying mechanisms. The primary aim of the current study was to examine the effect of differently shaped glasses on time taken to drink a soft drink. The secondary aim was to develop hypotheses about mechanisms concerning micro-drinking behaviours and perceptual effects.

METHOD

In a single-session experiment, 162 participants were randomised to receive 330ml of carbonated apple juice in a glass that was either inward-sloped, straight-sided, or outward-sloped. The primary outcome measure was total drinking time. Secondary outcome measures included micro-drinking behaviours (sip size, sip duration, interval duration), and perceptual measures (midpoint bias, drink enjoyment).

RESULTS

Participants drank 21.4% faster from the outward-sloped glass than from the straight-sided glass [95%CI: 0.2%,38.0%] in adjusted models. They were also 18.2% faster from the inward-sloped glass than the straight-sided glass, but this did not reach statistical significance with wide confidence intervals also consistent with slower drinking [95%CI: -3.8%,35.6%]. Larger sips were associated with faster drinking times (Pearson's r(162) = -.45, p < .001). The direction of effects suggested sips were larger from the outward-sloped and inward-sloped glasses, compared to the straight-sided glass (15.1%, 95%CI: -4.3%,38.0%; 19.4%, 95%CI: -0.5%,43.6%, respectively). There were no significant differences between glasses in mean sip or interval duration. Bias in midpoint estimation was greater for the outward-sloped glass (12.9ml, 95%CI: 6.6ml,19.2ml) than for the straight-sided glass, although the degree of bias was not associated with total drinking time (Pearson's r(162) = 0.01, p = .87).

DISCUSSION

Individuals drank a soft drink more quickly from an outward-sloped glass, relative to a straight-sided glass. Micro-drinking behaviours, such as sip size, are promising candidates for underlying mechanisms.