finished my first 36 hour fast. Already lost more than 1 kg, how long can I keep this up?

I finished my first 36 hour fast, I felt discomfort but I went from 89 kg to 87.8 kg in just 36 hours??

I felt a lot of discomfort as expected and my hands are very cold while typing as well (as glycogen drops so its normal while fasting). I had many cravings throughout but I fought through.

Is it safe to continue this again tomorrow? My goal is to get to 80 kg by January 30th. I feel fasting might be my way to my goal but I don't know if its sustainable and I can continue. Anyone been in a similar boat can help?