I've thought about your question logically ( I'm not a CDC, just a nurse). I wouldn't if I were you. I can't imagine that the diet would effect your major blood constituents, your cells but it is likely to alter the minerals in your blood. So your plasma wouldn't be the same? Plus you wold have higher levels of ketones in it. Your kidneys are working hard right now so I would hesitate to give them extra work.....I wouldn't be doing CD if I didn't think it was safe but I'd hesitate to let my blood go...I need it! I may be wrong!