It's a last resort because adults can't reliably stick to the diet and doctors know it. People don't even stick to medication very well. It's really only prescribed in kids with severe forms of genetic epilepsy because it works well for those conditions, and their parents control what they eat. It's a lot easier to take a pill than to change your entire lifestyle.

Unfortunately, keto doesn't always control seizures either. Pills still work better than diet for some people.