for reference, im 5’4” and around 46-47kg (last time i checked- it’s likely gone up since then).
Are you concerned about losing too much? I did a ten-day fast recently (5 days dry). You lose the 6-10 pounds of water weight very fast, but will gain that all back after you return to carbs (you don’t weigh much, so you’ll probably be on the lower edge of this spectrum). Then I tend to lose about 1.5-2 pounds per day of the dry fast (your mileage may vary). Chances are you’ll be down about 12-15 lbs after the fast, which will be potentially scary, but a lot of it will come right back in a few days. The rest of the weight should return in a couple of weeks to a month.
For reference, I’m 165 lbs. I was down to about 138 lbs by the end of the fast, but was back to 165 in 3 weeks.