Question about fasting until completion?

Okay, I've been fasting for 22 days now. I currently weigh 165 lbs and I'm 5'11", so that's alright, I guess. I'd like to go down to 140. But I used to check out this forum before my fast and people were talking about fasting until completion?

This may sound like stupid question that's asked many a time, but what exactly does fasting until completion mean? Does that mean until your tongue stops with the awful taste/discoloration? Or until you feel actual hunger? How does one know when actual hunger returns? Like, my stomach growls, but I don't know if that's hunger or what.

My throat feels weird and feels like it's closing up sometimes. Sometimes, it feels like I'm getting heart burn. Does anyone know WHY this is caused? And when I went to the fair, I almost threw up because the smell of grease when my friend ate these fried mini donuts. Ew... But it seems that I'm appealed to fruits more than usual. I don't why, but they look so good.

Sorry for the question. I know it's probably been asked a lot, but I just wanted to know. Thanks a lot. This forum has been helpful.