I've been on Keto for about 5 weeks. I had no idea of this theory, I was just supporting my wife with her weight loss journey after having baby. I've lost almost 20 pounds, yay! Anyway, I haven't been specifically looking for changes in my fluency. But I wouldn't say that I have noticed a significant change. That doesn't mean it couldn't be different for someone else. But I would caution anyone to try it as a fun experiment. What helped me the most is working on acceptance and talking to others in my local NSA chapter. I also do toastmasters to work on my confidence in the fluency I have. Good luck!