After 90 days of the keto diet you will likely see some significant weight loss results. Those with significant weight to lose could drop as much as 30lbs of fat in this time, though of course results vary.
The ketogenic diet has been shown in controlled studies to be effective in children and adults who have failed two lines of standard antiseizure medication. However, it is not safe for use in people with certain genetic conditions that affect the metabolism of fatty acids.