the effectiveness of workplace dietary interventions protocol for a systematic review and metaanalysis background the lack of evidence of the role of workplaces as settings for behaviour change delivery and the failure to recognise and address the complexity of the work environment has been acknowledged this systematic review and metaanalysis will identify the effectiveness of dietary interventions in the workplace facilitating an understanding of what works why and how by identifying key components of and examining the theoretical models of behaviour change underpinning successful dietary interventions in the workplacemethodsdesign we will conduct searches in medline embase cinahl psycinfo central and pubmed for studies that assess dietary interventions based within workplace settings in any country of any length of time or duration of followup we will include all randomised controlled trials rcts nonrandomised controlled trials nrcts controlled beforeafter studies cbas and interrupted time series its studies with a control group risk of bias of included studies will be assessed using a tool adapted from the cochrane public health review groups recommended effective public health practice project quality assessment tool for quantitative studies metaanalysis will be conducted if appropriate or a narrative synthesis will be conducted following the esrc narrative synthesis guidancediscussion this paper outlines the study protocol for a systematic review and metaanalysis that will identify critically appraise and summarise the relevant evidence on the effectiveness and implications of interventions to promote healthier dietary behaviours in the workplace this review will give an overview of the evidence and provide a guide for development of interventions promoting dietary behaviour change in workplacessystematic review registration prospero crd42015015175