The ketogenic diet was first tested as a treatment for epilepsy in the 1920’s. It was relatively successful and was used as a form of treatment. The diet basically consists of a very low daily carbohydrate content (15 or so grams per day) with the bulk of the remaining calories consumed coming from fat and a small amount of protein.
This diet was never meant to be used for weight loss rather it was meant as a clinical treatment for a disease state. But somehow just about any nutrition intervention (no matter what it’s for) ends up getting turned into a diet/weight loss program.
Anyway here is the quick review of what ketosis is.
Ketosis is a state when your body does not have sufficient carbohydrate intake to fuel your normal daily functioning so it starts to rely more on ketone bodies (which are made from fat) as a primary fuel source.
This happens during starvation, however you can recreate this state by eating a zero carbohydrate diet.
After a few weeks of eating in this pattern most healthy individuals seem to be able to adapt to this style of eating although it’s not necessarily fun to do for more than a couple of days (which isn’t really long enough to really get into ketosis).
In other words, you’re likely not going to want to do this for very long if you don’t have to.
The bottom line is that ketogenic diets are a rather extreme way to modify your diet. It’s not dangerous per se, but it’s also not necessary and probably unsustainable for most people. There is simply too many fun and tasty carbohydrate foods to eat (that can be incorporated into an effective weight loss program) to justify going on a restrictive ketogenic diet.
P.S. A simpler way to lose weight without restricting food choices is Eat Stop Eat, if you haven’t already read it I suggest you check it out.