 A study with an intent @-@ to @-@ treat prospective design was published in 1998 by a team from the Johns Hopkins Hospital and followed @-@ up by a report published in 2001 . As with most studies of the ketogenic diet , there was no control group ( patients who did not receive the treatment ) . The study enrolled 150 children . After three months , 83 % of them were still on the diet , 26 % had experienced a good reduction in seizures , 31 % had had an excellent reduction and 3 % were seizure @-@ free . At twelve months , 55 % were still on the diet , 23 % had a good response , 20 % had an excellent response and 7 % were seizure @-@ free . Those who had discontinued the diet by this stage did so because it was ineffective , too restrictive or due to illness , and most of those who remained were benefiting from it . The percentage of those still on the diet at two , three and four years was 39 % , 20 % and 12 % respectively . During this period the most common reason for discontinuing the diet was because the children had become seizure @-@ free or significantly better . At four years , 16 % of the original 150 children had a good reduction in seizure frequency , 14 % had an excellent reduction and 13 % were seizure @-@ free , though these figures include many who were no longer on the diet . Those remaining on the diet after this duration were typically not seizure @-@ free but had had an excellent response . 
