While other diet methods come and go, the ultra -low carbohydrate keto diet seems to last. But while scientists are starting to understand how the diet works, more is also discovered on its risks. To find out more, Madeleine Finlay speaks to Javier Gonzalez, professor in the health department of the University of Bath, with a particular interest in personal nutrition. He explains how the diet works, what he could do to our body and what could really be behind the weight loss that people experience