At most, your brain can run with 75% ketones/25% glucose. Other organs (kidneys, red blood cells, cornea) need about 15-25 grams/carb per day. If you do not get glucose from diet, your body will build it (gluconeogenesis).
Must see if you want to understand/practice keto right:
Must see if you want to understand/practice keto right:
https://www.youtube.com/user/chrismasterjohn/videos