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 health warning labels on selection and consumption of food and alcohol products: systematic review with meta-analysis

Health warning labels (HWLs) could reduce harmful consumption of food (including non-alcoholic drinks) and alcoholic drinks. A systematic review with meta-analysis using Cochrane methods was conducted to assess the impact on selection (including hypothetical selection) or consumption of food or alcoholic drink products displaying image-and-text (sometimes termed 'pictorial') and text-only HWLs. Fourteen randomised controlled trials were included, three for alcohol, eleven for food. For the primary outcomes, eleven studies measured selection and one measured consumption (two measured only other secondary outcomes). Meta-analysis of twelve comparisons from nine studies (n=12,635) found HWLs reduced selection of the targeted product compared with no HWL (RR=0.74 (95%CI 0.68-0.80)), with participants 26% less likely to choose a product displaying a HWL. A planned subgroup analysis suggested a larger (although not statistically significant) effect on selection of image-and-text HWLs (RR=0.65 (95%CI 0.54-0.80)) than text-only HWLs (RR=0.79 (95%CI 0.74-0.85)). These findings suggest significant potential for HWLs to reduce selection of food and alcoholic drinks, but all experimental studies to date were conducted in laboratory or online settings with outcomes assessed immediately after a single exposure. Studies in field and naturalistic laboratory settings are needed to estimate the potential effects of food and alcohol HWLs.Study registration: PROSPERO 2018 (registration number: CRD42018106522).

Policies for Tobacco and E-Cigarette Use: A Survey of All Higher Education Institutions and NHS Trusts in England

INTRODUCTION

There is an absence of evidence regarding the impact of treating tobacco smoking and vaping equivalently in workplace policies. We aimed to describe and compare smoking and vaping policies in acute nonspecialist NHS Trusts (n = 131) and Higher Education Institutions (HEIs) (n = 131) in England.

METHODS

We conducted a census of smoking and vaping policies through organizational websites searches and direct requests for information. We recorded whether and where smoking and vaping were permitted.

RESULTS

Smoking was prohibited indoors in all organizations. No NHS Trust permitted smoking freely outdoors, in contrast with 60% of HEIs. In 27% of NHS Trusts and 33% of HEIs smoking was permitted in designated areas, while in 73% of NHS Trusts and 8% of HEIs smoking was prohibited anywhere on site. Vaping was prohibited indoors in all NHS Trusts and all but one HEI, but permitted freely outdoors in 18% of NHS Trusts and 75% of HEIs. Vaping was permitted in designated outdoor spaces in 23% of NHS Trusts: 21% had areas shared with smokers; 2% had separate vaping areas. Vaping was permitted in designated outdoor areas in 18% of HEIs, all of which were shared with smokers. Vaping was prohibited anywhere on site in 54% of NHS Trusts and 6% of HEIs.

CONCLUSIONS

Policies vary considerably in whether vaping and smoking are treated equivalently. Smoking policies in most HEIs should be reviewed to include more effective tobacco control approaches. Evidence is needed on the impact of imposing shared or separate spaces on vapers and smokers.

IMPLICATIONS

This report provides a comprehensive review of smoking and vaping policies in two types of organization across England. It highlights key discrepancies between current public health recommendations for vaping and existing workplace policies, which often lead to smokers and vapers sharing spaces. The report identifies the need for evidence on the impact of imposing shared spaces on smokers and vapers to inform workplace policies that maximize public health benefit.

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).

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.

From Face-to-Face to Facebook: Probing the Effects of Passive Consumption on Interpersonal Attraction

Social media is radically altering the human social landscape. Before the internet era, human interaction consisted chiefly of direct and reciprocal contact, yet with the rise of social media, the passive consumption of other users’ information is becoming an increasingly popular pastime. Passive consumption occurs when a user reads the posts of another user without interacting with them in any way. Previous studies suggest that people feel more connected to an artificial person after passively consuming their Facebook posts. This finding could help explain how relationships develop during passive consumption and what motivates this kind of social media use. This protocol proposes two studies that would make both a methodological and a theoretical contribution to the field of social media research. Both studies investigate the influence of passive consumption on changes in interpersonal attraction. The first study tests whether screenshots, which are widely used in present research, can be used as a proxy for real Facebook use. It measures the changes in interpersonal attraction after passive consumption of either a screenshot, an artificial in situ profile, or an acquaintance’s real Facebook profile. The second study relies on traditional theories of relationship formation and motivation to investigate which variables (perceived intimacy, perceived frequency of posts, perceived variety of post topics, attributional confidence, and homophily) moderate the link between interpersonal attraction before and after passive consumption. The results of the first study provide insights into the generalizability of the effect by using different stimuli, while also providing a valuable investigation into a commonly used method in the research field. The results of the second study supplement researchers’ understanding of the pathways linking passive use and interpersonal attraction, giving the field further insight into whether theories about offline relationship formation can be used in an online context. Taken together, this protocol aims to shed light on the intricate relation between passive consumption and interpersonal attraction, and variables moderating this effect.