my details will be a little off but i did make a thread if you wanted to verify anything.
i lost 8.4ish pounds in the 3 days on pure water fast at a final weigh around 148 pounds at 5’10”. i am middle aged male and did some wood splitting for a couple hours during the fast but otherwise not too active.
I think this really depends on your starting point. Someone already on a low carb diet will appear to lose far less than someone on a traditional diet because they’ve already lost their water weight. I’d just stick with the basics of your calories in vs calories out to estimate your results.