Abstract
Background: Most research indicates that significant dietary change is difficult to initiate and maintain but also that it is feasible for a minority of individuals. Aims: The thesis aimed to investigate the phenomenon of dietary change across the lifespan using four different research methodologies. Methods: A systematic review was conducted to ascertain evidence for a health-benefiting, long-term dietary change. A qualitative study was carried out in which twenty participants’ narratives of dietary changes across their lifespan were analysed using Interpretative Phenomenological Analysis. To assess the prevalence of dietary change, a study with a cross-sectional design operationalized the results obtained in the qualitative study. Finally, an intervention was carried out in the university canteen to test one of the mechanisms of dietary change identified in the qualitative study. Results: The systematic review supported evidence for highly motivated participants’ successful dietary change in the long-term. The qualitative study revealed that dietary change can occur either with or without the individual’s active involvement through processes that were labelled: active path and passive path. Four themes emerged, denoting the mechanisms of dietary change: accumulation of evidence, trigger to action, imposed change and seamless change. These were operationalized in the survey, which suggested that dietary change appears to be a frequent occurrence in the lives of both men and women regardless of their socioeconomic or ethnic background. The results of an intervention in a cafeteria showed the efficacy of two ways of Imposing Changes on customers: changes in location of fruit and confectionary and the reduction of food choices at lunch time. Both were shown to influence customers’ purchases. The sales of fruit and brown baguettes rose as a result of intervention. Conclusions: These results indicate that dietary changes are not as infrequent and difficult as often assumed and that they happen across the lifespan for most people. Dietary change happens in a passive or in an active way with four underlying mechanisms.