Barriers to and facilitators of implementing complex workplace dietary interventions: process evaluation results of a cluster controlled trial

A much-needed qualitative analysis of workplace interventions focusing on what can help or hinder dietary change using the workplace as the site for change was led by Sarah Fitzgerald, a PhD scholar at the HRB Centre for Health and Diet Research.

The workplace has been identified as an ideal setting to promote healthy dietary behaviours as two-thirds of people’s waking hours are spent at work. However, the effectiveness and cost-effectiveness of workplace dietary interventions are uncertain.

About the study

As part of the Food Choice at Work study, funded by HRB Centre for Health and Diet Research, the Irish Heart Foundation and the Nutritional and Health Foundation, four large manufacturing workplaces in Cork, with a minimum of 250 employees and a daily workplace canteen, were identified and approached to be included in a clustered non-randomised controlled trial.

A total of 850 participants across the four workplaces took part in the study. Participants were measured at baseline for dietary intakes and health status (BMI, waist circumference and blood pressure). They were subsequently followed up at 3–4 months and finally at 7–9 months. Three interventions (nutrition education, environmental dietary modification and a combination of both nutrition education and dietary modification) and a control group were allocated across the four organisations.

In terms of the process evaluation, purposive sampling was used within these organisations to recruit management stakeholders and employees to participate in semi-structured interviews. A total of 27 participants were chosen with roughly 50% from management. Participants were measured at baseline for dietary intakes and health status (BMI, waist circumference and blood pressure). They were subsequently followed up at 3–4 months and finally at 7–9 months.

Three interventions (educational, environmental and a combination of both – see Table 1) and a control group were split over the four organisations.

Four core themes emerged from the interviews: perceived benefits of participation; negotiation and flexibility of the implementation team; viability and intensity of intervention design; and workplace structures and cultures.

Change theory model

The Kurt Lewin change theory model, based around a 3-step process Unfreeze, Change and the Refreeze, was incorporated into this study. The researchers foresaw the first stage, marked by inertia, and initiated consultations before the study began between the research team and workplace stakeholders. This facilitated buy-in and ownership of the idea of change.

According to Lewin, once stakeholders have taken ownership, change can start. The change process can be a very dynamic one and, if it is to be effective, it will probably take some time and involve a transition stage. This stage meant implementing the Food Choice at Work interventions (Table 1) while negotiating with structural resistance and general issues. This part was a challenge to the researchers but, as noted in the study, flexibility on the part of the researcher as well as the organisations was key.

The final stage – ‘Refreezing’ – is the process of setting new norms whereby the intervention, although considered radical at the beginning, is now taken on board and becomes fixed in the workplace culture of the organisation.

Success of intervention

The success of this is reflected in the words of one of the catering managers who helped to execute the combined intervention:

“Even though the study is over, it still continued. There was no dramatic ‘okay that’s done go back to the old ways’ – there are a lot of things that we kept on board.” (Catering manager, combined intervention site – follow-up stage).

The study also demonstrated how process evaluations can be used to explore factors that may influence implementation in controlled intervention studies.

Further information

Sarah Fitzgerald

Sarah Fitzgerald is a HRB PhD Scholar in Health Services Research at the Department of Epidemiology and Public Health.

To read more about Sarah and her work, see

To read more about Sarah’s study, see the published article at BMC Health Services Research.

To read more about the Food Choice at Work project, see the extensive and accumulating outputs from this CHDR spin-off company.

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