A Health App Using Recipes and Education Components to Facilitate Sustainable and Healthier Diets.

As the app has not been evaluated before in terms of its impact on dietary change, the first intervention group will have the app as it stands. The overall aim of the syd is to improve general wellbeing across several health-related domains, which is achieved through engaging with its main features (the daily plan, journal, user profile, and chat function).

The plant-forward recipes and information pages available on the app will be made more salient for app users in this group through sending them via targeted messages in the chat function at specific times. Each day, the information pages will be sent at 09:30 and the recipes will be sent at 13:00.

The (no app) control group will be sent general health and sustainability information via email immediately after randomisation is done. To incentivise participation in both baseline and follow-up assessments, the control group will be offered lifetime access to the app and a summary of their self-reported food intake at week 10. The control group will be sent one email reminder halfway through (week 5) to remind them that they are involved in the study, provide them with instructions on the follow-up assessment, and that they will receive the intervention and dietary feedback at week 10.