"During the initial stages of this process, the adult brain does not burn ketones; however, the brain makes immediate use of this important substrate for lipid synthesis in the brain. After about 48 hours of this process, the brain starts burning ketones in order to more directly utilize the energy from the fat stores that are being depended upon, and to reserve the glucose only for its absolute needs, thus avoiding the depletion of the body's protein store in the muscles."
Kilde: http://en.wikipedia.org/wiki/Ketosis

" In addition, the liver begins to break down certain proteins into their constituent amino acids to make glucose (gluconeogenesis). Since most cells in the body can use ketone bodies for energy if glucose is unavailable, non-starvation diets low in carbohydrates seldom result in dangerously low levels of blood sugar (hypoglycemia), or dangerously high levels of ketones also known as ketoacidosis. People who eschew low carbohydrate diets cite hypoglycemia and ketoacidosis as a risk factor, but these issues are only problematic for people such as diabetics, who already have gluconeogenesis and ketone body regulation impairments."
Kilde: http://en.wikipedia.org/wiki/Low-carbohydrate_diet

Så lenge dietten er kontrollert, med nok protein og nok fett. Så er det ingen problem å gå på en ketose diett.