I have and saw the predictable change when I stepped on the scale. However, I've come to learn that while this is a universally attractive thing, it's deceiving. You're losing water weight and muscle mass. More disturbingly, ketones observed with cancer cells in a petri dish act as fuel to help the cancer cells multiply. Everyone has cancer cells. It's only a matter of your habits if or when those cells decide to become a problem. There are no long-term benefits for anyone. The only exception is if you're epileptic. The research army at nutritionfacts.org has done well to balance the available evidence -- and it's a considerable task.