Ketones are for good and also for bad. A high amount of ketones can result in diabetes. You can check the amount of ketones in your body by doing a urine test, and it will be able to tell you quickly the current levels in your body.
If you are a 200 lb male, this would be a typical day in the KETO diet. For breakfast you would have 5 whole eggs, 3 egg whites, coffee, with whole cream. For a snack you would have a juice with whey protein and no sugar added peanut butter. For lunch, you would have 8 ounces of meat or fish with fresh veggies. For a snack with lean protein and half a cup of nuts. Dinner can be the same as lunch with 8 ounces of meat or fish with veggies. Before bed, the last snack the same as your breakfast with whole cream. Remember, this is for a 200 lb male that is training. People have said that they have "brain fog" because of the ketosis to occur when your ketones are being pushed to your brain.
Consuming high amounts of fats goes against all that we've been told. We've been told to stay away from fat. But, there are tons of studies out there that show the KETO diet have a positive effect on our cholesterol and triglycerides. As far as the long term, there aren't too many studies that go above 24 weeks in providing factual statistics. We can maintain optimal performance so long as you are ingesting 2-3 grams of sodium and potassium.
You would do 7 straight days of KETO, with 2 days of carbs, and so on. It will take 5 days for your body to get past the ketogenesis. On your carb days, make sure not to go above your maintenance calories otherwise you might intake fat instead of muscle.