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.
Ontology highlight
ABSTRACT: 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).
SUBMITTER: Reynolds JP
PROVIDER: S-EPMC6889705 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:BackgroundOverconsumption 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 findingsThis 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).ConclusionsDecreasing 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 registrationISRCTN registry ISRCTN87225572.
| S-EPMC8439477 | biostudies-literature
Project description:Increasing the proportion of healthier foods available could encourage healthier consumption, but evidence to date is limited in scope and quality. The current study aimed to: (a) examine the feasibility and acceptability of intervening to change product availability in worksite cafeterias; and (b) estimate the impact on energy purchased of increasing the proportion of healthier (i.e. lower energy) cooked meals, snacks, cold drinks and sandwiches. Six English worksite cafeterias increased the proportion of healthier foods available, aiming to keep the total number of options constant, in a stepped wedge randomized controlled pilot trial conducted between January and May 2017. The intervention was generally successfully implemented and acceptable to clientele. Generalized linear mixed models showed a reduction of 6.9% (95%CI: -11.7%, -1.7%, p?=?0.044) in energy (kcal) purchased from targeted food categories across all sites. However, impact varied across sites, with energy purchased from targeted categories significantly reduced in two sites (-10.7% (95%CI: -18.1% to -2.6%, p?=?0.046); -18.4% (95%CI: -26.9% to -8.8%, p?=?0.013)), while no significant differences were seen in the other four sites. Overall, increasing the proportion of healthier options available in worksite cafeterias seems a promising intervention to reduce energy purchased but contextual effects merit further study.
| S-EPMC6335439 | biostudies-other
Project description:BACKGROUND:Reducing the portion sizes of foods available in restaurants and cafeterias is one promising approach to reducing energy intake, but there is little evidence of its impact from randomised studies in field settings. This study aims to i. examine the feasibility and acceptability, and ii. estimate the impact on energy purchased, of reducing portion sizes in worksite cafeterias. METHODS:Nine worksites in England were recruited to reduce by at least 10% the portion sizes of foods available in their cafeterias from targeted categories (main meals, sides, desserts, cakes). In a stepped wedge randomised controlled pilot trial, each site was randomised to a date of implementation, staggered fortnightly, following a baseline period of four weeks. Impact on energy purchased was analysed using generalised linear mixed modelling. We also assessed feasibility, acceptability, and fidelity of intervention implementation. RESULTS:Data from six of the nine randomised sites were analysed, with three sites excluded for not providing sufficient data and/or not implementing the intervention. The extent to which the intervention was implemented varied by site, with between 6 and 49% of products altered within targeted categories. Feedback following the intervention suggested it was broadly acceptable to customers and cafeteria staff. For the primary outcome of daily energy (kcal) purchased from intervention categories, there was no statistically significant change when data from all six sites were pooled: percentage change -?8.9% (95% CI: -16.7, -?0.4; p?=?0.081). Each of these six sites showed reductions in energy purchased, ranging from -?15.6 to -?0.3%, which were borderline statistically significant at two sites (respective percentage changes (95% CIs): -?15.6% (-?26.7, -?2.8); -?14.0% (-?25.0, -?1.2)). Secondary outcome data are suggestive of a compensatory increase in energy purchased from food categories not targeted by the intervention, with no overall effect observed on energy purchased across all categories. CONCLUSIONS:The results of this pilot trial suggest that reducing portion sizes could be effective in reducing energy purchased and consumed from targeted food categories, and merits investigation in a larger trial. Future studies will need to address factors that prevented optimal implementation including site dropout and application across a limited range of products. TRIAL REGISTRATION:( ISRCTN52923504 ). Registered on 20th September 2016.
| S-EPMC6097301 | biostudies-literature
Project description:BACKGROUND:For working adults, about one-third of energy is consumed in the workplace making this an important context in which to reduce energy intake to tackle obesity. The aims of the current study were first, to identify barriers to the feasibility and acceptability of implementing calorie labelling in preparation for a larger trial, and second, to estimate the potential impact of calorie labelling on energy purchased in worksite cafeterias. METHODS:Six worksite cafeterias were randomised to the intervention starting at one of six fortnightly periods, using a stepped wedge design. The trial was conducted between August and December 2016, across 17 study weeks. The intervention comprised labelling all cafeteria products for which such information was available with their calorie content (e.g. "250 Calories") displayed in the same font style and size as for price. A post-intervention survey with cafeteria patrons and interviews with managers and caterers were used to assess the feasibility and acceptability of the intervention. Intervention impact was assessed using generalised linear mixed modelling. The primary outcome was the total energy (kcal) purchased from intervention items in each cafeteria each day. RESULTS:Recruitment and retention of worksite cafeterias proved feasible, with post-intervention feedback suggesting high levels of intervention acceptability. Several barriers to intervention implementation were identified, including chefs' discretion at implementing recipes and the manual recording of sales data. There was no overall effect of the intervention: -0.4% (95%CI -3.8 to 2.9, p?=?.803). One site showed a statistically significant effect of the intervention, with an estimated 6.6% reduction (95%CI -12.9 to -?0.3, p?=?.044) in energy purchased in the day following the introduction of calorie labelling, an effect that diminished over time. The remaining five sites did not show robust changes in energy purchased when calorie labelling was introduced. CONCLUSIONS:A calorie labelling intervention was acceptable to both cafeteria operators and customers. The predicted effect of labelling to reduce energy purchased was only evident at one out of six sites studied. Before progressing to a full trial, the calorie labelling intervention needs to be optimised, and a number of operational issues resolved. TRIAL REGISTRATION:ISRCTN52923504 ; Registered: 22/09/2016; retrospectively registered.
| S-EPMC5950179 | biostudies-literature
Project description:BACKGROUND: Environmental interventions directed at portion size might help consumers to reduce their food intake. OBJECTIVE: To assess whether offering a smaller hot meal, in addition to the existing size, stimulates people to replace their large meal with a smaller meal. DESIGN: Longitudinal randomized controlled trial assessing the impact of introducing small portion sizes and pricing strategies on consumer choices. SETTING/PARTICIPANTS: In all, 25 worksite cafeterias and a panel consisting of 308 consumers (mean age=39.18 years, 50% women). INTERVENTION: A small portion size of hot meals was offered in addition to the existing size. The meals were either proportionally priced (that is, the price per gram was comparable regardless of the size) or value size pricing was employed. MAIN OUTCOME MEASURES: Daily sales of small and the total number of meals, consumers' self-reported compensation behavior and frequency of purchasing small meals. RESULTS: The ratio of small meals sales in relation to large meals sales was 10.2%. No effect of proportional pricing was found B=-0.11 (0.33), P=0.74, confidence interval (CI): -0.76 to 0.54). The consumer data indicated that 19.5% of the participants who had selected a small meal often-to-always purchased more products than usual in the worksite cafeteria. Small meal purchases were negatively related to being male (B=-0.85 (0.20), P=0.00, CI: -1.24 to -0.46, n=178). CONCLUSION: When offering a small meal in addition to the existing size, a percentage of consumers that is considered reasonable were inclined to replace the large meal with the small meal. Proportional prices did not have an additional effect. The possible occurrence of compensation behavior is an issue that merits further attention.
| S-EPMC3172584 | biostudies-other
Project description:BackgroundCalorie 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.MethodsThree 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.ResultsRecruitment 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.ConclusionsThere 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.
| S-EPMC8161726 | biostudies-literature
Project description:OBJECTIVES:To investigate the extent to which cluster sizes vary in stepped-wedge cluster randomised trials (SW-CRT) and whether any variability is accounted for during the sample size calculation and analysis of these trials. SETTING:Any, not limited to healthcare settings. PARTICIPANTS:Any taking part in an SW-CRT published up to March 2016. PRIMARY AND SECONDARY OUTCOME MEASURES:The primary outcome is the variability in cluster sizes, measured by the coefficient of variation (CV) in cluster size. Secondary outcomes include the difference between the cluster sizes assumed during the sample size calculation and those observed during the trial, any reported variability in cluster sizes and whether the methods of sample size calculation and methods of analysis accounted for any variability in cluster sizes. RESULTS:Of the 101 included SW-CRTs, 48% mentioned that the included clusters were known to vary in size, yet only 13% of these accounted for this during the calculation of the sample size. However, 69% of the trials did use a method of analysis appropriate for when clusters vary in size. Full trial reports were available for 53 trials. The CV was calculated for 23 of these: the median CV was 0.41 (IQR: 0.22-0.52). Actual cluster sizes could be compared with those assumed during the sample size calculation for 14 (26%) of the trial reports; the cluster sizes were between 29% and 480% of that which had been assumed. CONCLUSIONS:Cluster sizes often vary in SW-CRTs. Reporting of SW-CRTs also remains suboptimal. The effect of unequal cluster sizes on the statistical power of SW-CRTs needs further exploration and methods appropriate to studies with unequal cluster sizes need to be employed.
| S-EPMC5695383 | biostudies-literature
Project description:BackgroundOn 6 April 2022, legislation came into effect in England requiring calorie labels to be applied to food items on menus of larger food businesses. This study aimed to assess the impact of calorie labelling on (a) food purchased and (b) energy content of menu options in worksite cafeterias.MethodsProduct-level sales data and energy content of available items was obtained from 142 worksite cafeterias from January 2022-October 2022. Interrupted-time-series (ITS) analysis with level and slope change evaluated daily energy (kcal) purchased per item, and ITS with level change assessed mean energy per option available on menus before and after calorie labelling. Each analysis was conducted 6 weeks and 6 months from implementation. A post-hoc ITS examined weekly energy purchased per item over a longer period (March 2021-October 2022; 135 sites).ResultsThere was no evidence calorie labelling changed the energy content of foods purchased (6-week: + 0.60 cal/product, 95%CI:-2.54, + 3.75; 6-month: + 1.59 cal/product, 95%CI:-0.96, + 4.16). Post-hoc analyses suggested calorie labels were associated with a reduction in mean energy of items purchased over time (-0.65 kcal/week, 95%CI:-0.81,-0.49), but a significant increase (+ 3 kcal, 95%CI: + 0.43, + 5.60) at the point of implementation. There was a reduction in the mean energy content of menu options at each seasonal menu change (April 2022:-1.79 kcal, 95%CI:-3.42,-0.15; July 2022:-4.18 kcal, 95% CI:-7.65,-0.73).ConclusionThis large observational study in worksite cafeterias found no evidence to indicate the introduction of calorie labelling led to any immediate reduction in energy purchased by customers. There was some evidence of increasing impact over time, possibly associated with changes in menu offerings, but this effect was small and cannot be directly attributed to calorie labelling.
| S-EPMC11321062 | biostudies-literature
Project description:Accurate and easy-to-understand nutrition labeling is a worthy public health goal that should be considered an important strategy among many to address obesity and poor diet. Updating the Nutrition Facts Panel on packaged foods, developing a uniform front-of-package labeling system and providing consumers with nutrition information on restaurant menus offer important opportunities to educate people about food's nutritional content, increase awareness of reasonable portion sizes and motivate consumers to make healthier choices. The aims of this paper were to identify and discuss: (1) current concerns with nutrition label communication strategies; (2) opportunities to improve the communication of nutrition information via food labels, with a specific focus on serving size information; and (3) important future areas of research on nutrition labeling as a tool to improve diet. We suggest that research on nutrition labeling should focus on ways to improve food labels' ability to capture consumer attention, reduce label complexity and convey numeric nutrition information in simpler and more meaningful ways, such as through interpretive food labels, the addition of simple text, reduced use of percentages and easy-to-understand presentation of serving size information.
| S-EPMC4105581 | biostudies-other
Project description:Standard sample size calculation formulas for stepped wedge cluster randomized trials (SW-CRTs) assume that cluster sizes are equal. When cluster sizes vary substantially, ignoring this variation may lead to an under-powered study. We investigate the relative efficiency of a SW-CRT with varying cluster sizes to equal cluster sizes, and derive variance estimators for the intervention effect that account for this variation under a mixed effects model-a commonly used approach for analyzing data from cluster randomized trials. When cluster sizes vary, the power of a SW-CRT depends on the order in which clusters receive the intervention, which is determined through randomization. We first derive a variance formula that corresponds to any particular realization of the randomized sequence and propose efficient algorithms to identify upper and lower bounds of the power. We then obtain an "expected" power based on a first-order approximation to the variance formula, where the expectation is taken with respect to all possible randomization sequences. Finally, we provide a variance formula for more general settings where only the cluster size arithmetic mean and coefficient of variation, instead of exact cluster sizes, are known in the design stage. We evaluate our methods through simulations and illustrate that the average power of a SW-CRT decreases as the variation in cluster sizes increases, and the impact is largest when the number of clusters is small.
| S-EPMC7165039 | biostudies-literature