If the keto diet sounds difficult and complicated - well, it can be. With as little as 12 hours of fasting, your brain begins shifting toward ketone metabolism, and as ketosis ramps up, ketones can supply more than 60 percent of your brain’s energy, which helps it overcome the problem of sugar metabolism. In this case, a one-cup serving has more than a day’s worth of vitamin C and helps you get some much-needed fiber.