Workplaces are increasingly recognized as influential settings for promoting healthier dietary behaviours and improving employee well-being (1) . Numerous studies have examined the effectiveness of workplace nutrition interventions, but their theoretical foundations and underlying mechanisms remain insufficiently understood (2) . This study aimed to evaluate how Behaviour Change Theories are applied in workplace dietary interventions, and to assess associated implementation challenges and process evaluation practices in relation to organizational and business-related outcomes. This project was a secondary analysis of 168 studies identified in a previous systematic review investigating efficacy of workplace health and wellbeing programs that included a nutrition component on organizational outcomes (PROSPERO CRD42023454673). The first aim was to examine the extent to which Behaviour Change Theories were explicitly applied in workplace interventions and how this influenced outcomes. A further objective was to investigate reported implementation challenges and process evaluation elements, which were categorized through the same systematic extraction process. Analysis was conducted through systematic data extraction using three structured templates, one per objective, that enabled mapping of intervention components to theoretical frameworks and comparison across studies. The Behaviour Change Wheel and COM-B model guided the analysis, alongside Social Cognitive Theory, Theory of Planned Behaviour, Health Belief Model, Transtheoretical Model, and Behaviourist Theory (3) . Data extraction focused on theory use, methodology, implementation challenges, and process evaluation components (fidelity, reach, delivery). A narrative synthesis was undertaken. Of the 168 studies, 21 (12.5%) explicitly cited a Behaviour Change Theory. The most frequently used were Social Cognitive Theory (n=10), the Transtheoretical Model (n=5), and the Health Belief Model (n=5). In interventions explicitly citing theory, 14.3% (3/21) reported non-significant results, compared with 22% (32/147) of those without a cited theory. Process evaluation components were reported in most studies, with 72% addressing participant engagement or attendance and 33.9% including participant feedback for adaptation. However, no formal research-based fidelity assessments were reported. Implementation challenges occurred at organizational, individual, and external levels. Almost half of the interventions (45%) used pre-post assessments without control groups, limiting causal inference. Only 12.5% of workplace nutrition interventions explicitly cited a Behaviour Change Theory, most often Social Cognitive Theory or the Health Belief Model, yet theory-based designs tended to yield more consistent positive outcomes. Process evaluation elements such as engagement were often reported, but formal fidelity assessments were rare, and nearly half of studies relied on pre–post designs without control groups, limiting causal inference. Common implementation barriers included time constraints, limited leadership support, and workplace infrastructure challenges. Future research should more firmly ground interventions in theory, apply structured evaluation frameworks, and address barriers at both organizational and individual levels to strengthen effectiveness and long-term sustainability.
Burzin et al. (Fri,) studied this question.