when you fast your blood sugar doesn't keep dropping and dropping to 0. that is a common misconception that people think. when i did my prolong fast my blood sugar dropped into the 60's then rebounded a bit then went up and down in the 65-75 range. now why does this happen? because once you reach ketosis your body starts going after fat cells and you start excreting them. as this happens your blood sugar actually bounces up a bit. so in other words your blood sugar when fasting doesn't just drop and drop and drop down. it actually will stabilize and then bounce back as your body is releasing stored up glycogen from your liver. and trust me unless you are 2-3% body fat you have A LOT of stored up fat/glycogen that needs to be worked through.
now the only caveat is 2 things
1. you are on anti-diabetes meds/insulin
2. you have some sort of very rare medical condition seen in .001% of the population
otherwise that hypo feeling you are going through is just a sugar addiction. just like being addicted to alcohol, weed, drugs, or anything else. you have to fight that urge. it will take 2-3 weeks for your body to adjust. if you have spent your life throwing sugar and carbs at your body everytime you get 'hungry' you have trained your body to be too insulin resistant. you aren't alone. 33% of americans are insulin resistant and on the verge of becoming diabetics
when i first started training fasted i was miserable. hated it. but 3 weeks later i adjusted. now i can't train unless i am fasted. you are lighter, more agile, body isn't having do digest food while you train. its a clean way to train