I am in the same situation as Mattrix. Keto and fasting improve self control tremendously.
And to answer your question . . . the difference is not subtle, so it's really obvious. For example, I was fasting last Sunday and did 6 hours of housework on a day I would normally play video games. I am fasting right now, and am destroying my work, doing chores on breaks, and cooking food for dinner. I can smell delicious food in the crock pot that I can't have for another four hours, and I do want it . . . but the desire is bothering me approximately as much as unwanted birdsong. Which is to say I barely even notice.
It's a heck of a thing. Everyone should try it at least once.
