Gluten-free diets could be damaging to the health of people who do not have coeliac disease, raising the risk of obesity, diabetes and malnutrition, an expert has warned.

The diet, which excludes all food containing grains like wheat, barley and rye, such as bread and pasta, have been popularised by celebrities like Gwyneth Paltrow who claims cutting out gluten boosts health and aids weight loss.

Wimbledon champion Novak Djokovic, said it helped propel him to World No 1. while Victoria Beckham claims it is how she keeps her trim figure.