What is meant by a keto diet? Something that puts your body in ketosis? If so, how many days a week? I hear keto bandied about a lot, but not sure a) if everyo

What is meant by a keto diet? Something that puts your body in ketosis? If so, how many days a week? I hear keto bandied about a lot, but not sure a) if everyone's talking about the same thing, b) the difference between it and paleo, and c) if it's actually healthy :)