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

James P. Reynolds, Daina Kosīte, Brier Rigby Dames, Laura A. Brocklebank, Mark Pilling, Rachel Pechey, Gareth J. Hollands, Theresa M. Marteau

Research output: Contribution to journalArticlepeer-review


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:

Original languageEnglish
Article number1611
JournalBMC Public Health
Issue number1
Publication statusPublished - 2 Dec 2019


  • Availability
  • Choice architecture
  • Healthier eating
  • Nudging
  • Obesity
  • Physical micro-environment interventions
  • Portion size
  • Randomised controlled trial
  • Stepped wedge trial
  • Workplace interventions

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health

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