True to what it says

I think the key part is the ”if every day were like this”. Generally, no two days are exactly the same, let alone every day for five weeks. Even if they were, projected weight loss and actual weight loss are two different things.

Maybe... If you took the value every day and plotted it on a graph and then trended that. The average may be close. But it's only as reliable as your logging and honesty, and can be quite different when you account for monthly cycles, water weight, new exercises, etc.