To explore non-users perceptions of a realistic and tailored representation of an anatomical body (Digital Twin), which provides normative and risk information on a mobile health app. The aim was to investigate potential mechanisms important for behaviour change (particularly weight management). Design A qualitative methodology was used to explore the experiences of people, in this case non-users wanting to self-manage their health. Method Semi-structured interviews were carried out using Zoom. An explorative and participant-led approach was taken to allow the participant to express what was important to them. Twenty participants who had not used the Digital twin were recruited (13 females and 7 males; mean age was 30). The interviews were transcribed verbatim and analysed using Thematic Analysis. Results Four main themes were developed: Psychosocial initiators of behaviour change (health beliefs and social support); psychosocial facilitators or maintenance of behaviour (usefulness, cues to action and tailoring); barriers to mHealth app use (biases and sharing information); barriers to maintenance of behaviour change (adverse reactions, loss of motivation and sociocultural factors). The results will inform the design of an intervention for weight loss using the Digital Twin. Conclusion Overall, the participants responded positively to the concept of the Digital Twin. It was suggested that the Digital Twin should be tailored to represent their personalised health information and BMI. These results will feed into an intervention designed to use the Digital Twin to initiate and maintain weight behaviour change and will further our understanding of using such technology in behaviour change.