I'd like to chime in. I'm a big fan, but Ketogenic diets can be dangerous! I did less than 20g of carbs between October and January, with something more liberal the summer before. My ketosticks were 40 to 80. Over time my nearly (or actually) constant simple partials all but disappeared. I felt better, my brain fog was gone, I had more energy, and could get along with hardly any sleep when necessary. However, it caused or contributed to some problems which can be summed up as aging at a tremendous pace. I'm sure I wasn't getting enough nutrition, and I'm not sure that my body was able to handle all the the fat. I'm off the diet now and my seizures are coming back. Children on the diet experience a slowing of growth, which they can make up once they get off the diet. Kidneystones can be a problem. Constipation is a problem.
Based on my experience I would say that no one should do it without an epileptologist and a nutritionist who really know what they are doing. Johns Hopkins has an adult program. Something that would help a lot is getting a nutritionist to sign you up for the Charlie Foundation Ketocalulator, which will take a lot of guesswork out of it and help you maximize nutrition. If you are doing something less extreme, like Atkins, etc. it may not be as critical, but I would still advise regular blood tests with a team that knows what they are doing. I DID have a team, but they didn't know what they were doing, and were no help. Eventually I saw a qualified dietician, but it was too late.
I would consider doing it again in time with proper help. The hardest thing is locating food. If you don't have a great grocery everything is low fat and crammed full of sugar. Even the carbs in heavy cream start to add up. Sugar free stuff isn't. You have to be careful about quantities of vegetables. I REALLY missed healthy food. After the diet, the first time I ate a whole pear I thought I was in heaven. About the only thing you can safely order in a restaurant is a bunless cheeseburger (no American cheese) with bacon. You have to take cream with you everywhere.
Less restrictive diets are great if they are working for you. One thing the diet did for me is enlighten me as to how much pointless corn syrup and other added sweeteners are in everything. Carbs per se, like fruit, vegetables, or grains aren't bad for you (unless you are allergic). The gallons of corn syrup in low fat products is. No wonder people are so fat, it's not because they have pasta once and a while, it's because there are more than 2 tablespoons of sugar in fat free yogurt!