Ketogenic dietary therapies are an effective treatment option for children with drug-resistant epilepsy. There is an increasing worldwide interest in using these diets to manage adult epilepsy; uncontrolled studies show similar response rates to those in children. Despite this, there are only a few centres with dedicated services for adults. We clearly need controlled studies of this treatment in adults. Here, we aim to familiarise adult neurologists with the evidence base for these diets and give practical advice on starting and maintaining them in adults.