On a keto diet, the smell of acetone on your breath confirms ketosis, no need of blood/urine tests. I know from experience, it is very noticeable. I did a ketogenic diet many years ago, I didn't notice any difference in my speech, but I was much younger and my self-observation was limited, so maybe I'll consider do it again and see results on speech. Anyway, as I understand it, keto diet are not healthy in the long term. Thank you for the idea. (sorry my english, i'm spanish)