Dr Deirdre Cowman is a psychologist, lecturer at All Hallows College, Dublin, and representative for Endangered Bodies (endangeredbodies.org) an organisation promoting positive self body image.
She says: "Research suggests that focusing on the functionality of our bodies, rather than on appearance, may contribute to positive body image, which may in turn be related to our overall self-esteem. While I've not come across any published research on the impact of 'mirror fasts', it may be an effective way to help people to focus on qualities other than appearance.
"But interestingly, research has also pointed to the value of mirror exposure in helping individuals with negative body image and it could be argued that avoiding mirrors completely may perpetuate unrealistic negative beliefs about our appearance.
"While the mirror fast is an interesting and challenging idea, if we really want people to be less concerned about their appearance, we also need to address the unrealistic and limited images of bodies that we see in mainstream media."