You should never EVER post your phone number on line. It's not safe.
If you have 80# to lose, the longest I'd fast is 30-40 days, like the above poster said. After that, break for a week or two and do a plant based (no fat no oil no animal no dairy) diet, just whole grains, beans, veggies, and fruits. Do it for a couple weeks, then start tapering your food and start fasting again for 20-30 days. Repeat until weight is lost then do not deviate from whole plant diet and your weight should stay off. Add exercise as you are able.
You have to white knuckle the first 3-4 days of a fast, after that you should not feel hunger of if you do it comes and goes and should be tolerable. That's why people can go for days on end, because ketosis decreases hunger.
There's a YouTube series of a woman who did three consecutive 40-day fasts and she seemed fine, but YMMV. I can't imagine the mental focus it takes to do something like that, it would be beyond my ability. She even worked while she did it and had a bunch of kids. Good luck!