I've been breaking ketosis regularly since February which is 3 months after my fast. When you go long with it, you feel a buzzing sensation. Feels like it's in the blood. As though countless into the trillions of DNA ori is grinding away at unused reserves for replication and the gears of the Helicase is grindy, and it's happening to all of them over time gradually until all of them are grindy, the blood really seems to fizzle. Totally feels like soda. I think that causes the body to dehydrate quicker which is why we take electrolyte supplements when going long to stay hydrated.
It does feel like its in the blood. Or maybe its because your veins start to pop from forearms.