This study is a pilot trial of a smartphone app to promote sustainable and healthy eating, running for 10 weeks. The app aims to promote general wellbeing in the working population. The investigators are interested in the feasibility and acceptability of the plant-based recipes and information pages, so the focus will be on how people engage with these features and how they meet their needs.

Participants will be randomised into three groups:

1. General information (no app).
2. Standard app (app as it stands).
3. Enhanced app with recipes and behaviour change recommendations (app + messages).

Data on demographics and food choice will be collected at the start and end of the intervention. A subset of participants will also take part in short interviews to talk about their experiences.

Overall aim:

This pilot trial aims to understand the feasibility and acceptability of a health and wellbeing app. The main focus is around the plant-based recipes and information pages delivered through the chat functionality.

Specific objectives:

The primary objective is to understand the feasibility and acceptability of setting up and running a trial with the app, focusing on the reach, adoption, implementation, and maintenance. The secondary objectives are to explore the indicative efficacy of the app in facilitating more sustainable and healthier diets, measured by a change in meat and legume intake, to what extent the recipes and information pages contribute to this effect, and whether there is a relationship between the self-perceived capabilities, opportunities and motivations to consume a sustainable and healthier diet.

Intervention:

The overall aim of the app is to enhance general wellbeing. The information pages contain general information on certain aspects of diets for health and sustainability. The recipes are available for breakfast, lunch and dinner, and vary in their composition of healthy and sustainable foods.

Sample size:

The target sample size will be 99 (33 per arm), which will account for the possibility of 40% dropout in the first two weeks, which is typical for smartphone apps, and would still suffice the rule of thumb for 25 per group to be included in a pilot study to yield a small standardised effect size.

Outcomes:

Outcomes (and data) that will be collected and include 1) programme reach (population characteristics), 2) adoption of the app (participation and retention rates), 3) acceptability of the intervention (engagement with and usefulness of the app features), 4) implementation of delivering the intervention (compliance), 5) maintenance of the intervention (participant and organizational sustainability), and 6) efficacy of the intervention (indications of change in behavioural determinants and behaviours).

Inclusion Criteria:

• Have a personal (not work) smartphone
• Have access to WiFi at home
• Have an out-of-home data package
• Be 18 years of age or older

Exclusion Criteria:

• Underweight for their age and gender
• Follow a restrictive diet (e.g., pregnant, breastfeeding, food intolerant/allergic, attempting to lose weight, diabetes, cardiovascular disease, or other long-term disease including eating disorders)
• Have a mental disability or learning difficulty

The investigators plan to upload IPD and related data dictionaries available on LSHTM's data repository called Data Compass.

Beginning 3 months and ending 10 years after the publication of results.

The data will be provided to other researchers for use in secondary research upon reasonable request through LSHTM's Data Compass repository. The provision of data will be subject to information being provided on the research objectives and ethics status of the project. Ethical approval will need to be sought before receiving the data.