A cult of clean eating is a “ticking timebomb” that could leave young people with weak bones, the National Osteoporosis Society has warned.

Research by the charity shows that four in ten of those aged between 18 and 24 have tried such regimes, which are now coming under attack for cutting out major food groups, such as dairy.

The diets have become increasingly fashionable, and are associated with a number of celebrities, who have boasted how they have cut out gluten, dairy, grains and refined sugars.