Not true. The body can also operate in a ketosis state, including the brain.
Actually, the heart muscle and kidneys, prefer ketones to glucose as their energy source. The brain does not use glucose as its sole energy source.
Learned something new, thanks. (Not the first time I’ve discovered my pathophysiology teacher over-simplified.)
http://en.wikipedia.org/wiki/Ketone_bodies
You missed the part that people like my husband just keep on losing weight on the Atkins diet, looking purely anorexic.