This report explores some of the current body of research within the field of persuasive technologies, specifically in the context of health and dietary habits. Additionally, an approach aimed to explore a gap in the current body of research is proposed. Specifically, the approach is concerned with technology-assisted intervention design for shoppers when they are shopping at a supermarket. A prototype smartphone application was developed and deployed in the field to 11 participants for a total of 5 weeks of study. The persuasive properties of the prototype are facilitated by notifying the participants of an overview of their recent purchases related to the Danish food pyramid. Detailed findings are presented in the enclosed research paper, and includes just-in-time considerations for persuasive design of technologies used in an in-situ context. This report is concluded by design proposals and suggestions for further research on persuasive technologies.