Summary
The ViTraS project was a BMBF-funded research initiative led by the University of Würzburg. Its main goal was to explore how eXtended Reality (XR) can support improving outcomes in therapy for body image disorders. The project focused especially on obesity, a major global health challenge with significant health and socioeconomic impacts, where relapse after weight loss is common. ViTraS investigated how XR’s unique capabilities could foster body awareness, improve body perception, motivate healthy eating behaviour, and enhance therapy engagement by supporting realistic goal setting.
Motivation
Obesity is a complex health issue involving both physiological and psychological factors, such as reduced body awareness, distorted body image, and low self-esteem. Effective treatment benefits from integrated psycho-physical approaches, not just isolated interventions. Previous investigations on XR-based treatments for these disorders showed promise, but often lacked immersion, realistic self-representations, or interactive, first-person experiences. ViTraS addressed these gaps by developing photorealistic, modifiable, embodied avatars and active, goal-oriented interaction techniques.
Concept
To address prior limitations, ViTraS focused on two main XR exposure experiences, utilizing XR-specific effects as key factors for behavioral and perceptual adaptations:
- Mirror exposure in XR: Participants interacted with a realistic self-avatar in a virtual mirror, dynamically adjusting weight and body shape. This allowed them to visualize self-perception, calibrate therapy goals, and safely explore “what-if” scenarios.
- Self-sketch, self-touch, and body swapping exercises in XR: Multisensory interactions enabled haptic and visual engagement with the avatar, supporting richer embodiment and subjective feedback for reflection and therapeutic dialogue.
Both concepts emphasized first-person experiences with personalized, high-fidelity avatars and interactive features, aiming to heighten emotional salience, deepen the sense of ownership, and translate insights into real-world motivation and action.
Technological Approach
Photorealistic Avatars: ViTraS started with a 360° DSLR rig and avatar reconstruction pipeline, later moving to a 180° multi-view system (front, right, back, left) for a more accessible setup. Ultimately, a smartphone-based method was developed, achieving realistic avatars with minimal hardware requirements, making the technology more scalable and affordable.
Body Weight Manipulation: To enable interactive weight change in XR mirror exposures, ViTraS used a statistical model based on the CAESAR body-scan dataset and a principal component analysis (PCA) to identify shape directions linked to weight. Adjustments were refined to preserve facial identity, so users could explore body changes without losing self-recognition.
Avatar Embodiment in XR: The developed ViTraS application relies on a modular Unity architecture, with reusable components for tracking, avatar retargeting and animation, networked distribution, and rendering on different XR devices. Body tracking evolved from marker-based to markerless multi-camera systems, reducing bodily intrusion and increasing comfort and accessibility. Interaction surfaces and controls were designed to be easy to use for people facing mobility limitations, as is often the case with obesity.
Outcomes and Impact
ViTraS resulted in more than 30 peer-reviewed scientific publications in top venues. The project demonstrated that XR can be tailored to the psycho-physical needs of individuals with obesity, showing high acceptance and strong therapeutic potential. The results established foundations also for applications in related disorders, such as anorexia nervosa. ViTraS received notable awards and media coverage, reflecting its scientific merit and societal relevance.
Media
ARD featured ViTraS in their documentary “Mein Körper. Mein (Mehr-) Gewicht”.