feeling light headed and shaky

I’m feeling light headed and shaky at times. I’m at the very beginning of cutting out sugar, eating until I’m satisfied and not “over full”, and not eating between meals and fasting at least 12 hours at night. Is this a part of the process of fat adaptation? I know I’ve felt like this before when I’ve cut calories and my response has been to eat more because I get panicked that I’m going to die if I’m feeling so shitty by not eating enough! LOL. If this is normal, typically how long does it last? Thanks!