I think the intuition behind Ketone drinks is completely fine for cyclists; pretty much all cyclists follow a high-carb, low-fat diet to maximise body glycogen stores, but the liver doesn't produce as much Ketones as if they were following a Ketogenic, high-fat, low-carb diet, and they use the drinks to promote the levels of these molecules. I wouldn't outright say it's natural but it definitely isn't a performance enhancing "drug" per say.

That being said, Ketone drinks are definitely widening the gap between WorldTour level teams and Continental level teams - I read somewhere that a litre of Ketone drink can cost you upwards of $1000. Just a dip in the ocean for Team INEOS or any of the other big cycling team, but for a low-budget continental team trying to get exposure it 's not a level playing field. For that reason I think they should be banned completely by the UCI.