The other trials compared types of diets or ways of introducing them to make them more tolerable. In the largest trial of the ketogenic diet with a non-diet control, nearly 38% of the children and young people had half or fewer seizures with the diet compared 6% with the group not assigned to the diet. Two large trials of the Modified Atkins Diet compared to a non-diet control had similar results, with over 50% of children having half or fewer seizures with the diet compared to around 10% in the control group. A systematic review in 2018 looked at 16 studies on the ketogenic diet in adults. It concluded that the treatment was becoming more popular for that group of patients, that the efficacy in adults was similar to children, the side effects relatively mild. However, many patients gave up the diet, for various reasons, and the quality of evidence was inferior to studies on children. Health issues include high levels of low-density lipoprotein, high total cholesterol, and weight loss. Indications and contraindications The ketogenic diet is indicated as an adjunctive (additional) treatment in children and young people with drug-resistant epilepsy. It is approved by national clinical guidelines in Scotland, England, and Wales and reimbursed by nearly all US insurance companies. Children with a focal lesion (a single point of brain abnormality causing the epilepsy) who would make suitable candidates for surgery are more likely to become seizure-free with surgery than with the ketogenic diet. About a third of epilepsy centres that offer the ketogenic diet also offer a dietary therapy to adults. The two less restrictive dietary variants—the low glycaemic index treatment and the modified Atkins diet—are more appropriate for adolescents and adults, mainly due to better adherence. A liquid form of the ketogenic diet is particularly easy to prepare for, and well tolerated by infants on formula and by others who are tube-fed. Advocates for the diet recommend that it be seriously considered after two medications have failed, as the chance of other drugs succeeding is only 10%. The diet is recommended earlier for some epilepsy and genetic syndromes where it has shown particular usefulness. These include Dravet syndrome, infantile spasms, myoclonic-astatic epilepsy, tuberous sclerosis complex and for children fed by gastrostomy tube. A survey in 2005 of 88 paediatric neurologists in the US found that 36% regularly prescribed the diet after three or more drugs had failed,