Warning on web 'thinspiration'

A total of 85 per cent contained "thinspiration" photographs, while 83 per cent offered encouragement for disordered eating behaviours.

Some websites contained "very hardcore" information to fuel eating disorders and 79 per cent had calorie counters or body mass index (BMI) calculators.

The study of 180 websites aimed at people with disorders such as anorexia and bulimia, was carried out by experts at the Johns Hopkins Bloomberg School of Public Health in the US and the Stanford University School of Medicine.

They found many websites had forums where sufferers could contact each other for ideas, yet most websites also recognised eating disorders as a disease and around a third had information on recovery.

Dina Borzekowski, lead author of the study, said: "Some of the reviewed sites present very dangerous ideas and disturbing material that serve to inform and motivate users to continue behaviours in line with disordered eating and exercise behaviours.