It's not unusual to see your weight go up and down 4 to 6 pounds from day to day depending on what's in your system.

Yes I read this, that's why I made sure to include information that shows how I know that it's outside of what to expect from daily fluctuations.

I understand that we see such variations in populations but I don't need to use population data since I have available the data that's specific to me, and no such dramatic shift has occurred until now. In fact, I had enough data that I could accurately predict my expected weight based on consumption within a few 10ths of a pound 90% of the time.

Your weight fluctuates because of the amount of waste you might have in you, water intake, how much food you ate, etc. I'm just trying to figure out physically/scientifically, what could account for that change? I didn't lose that much waste, I didn't sweat a lot, nothing about my eating has changed. So if maybe I'm missing one of the contributing factors to daily fluctuations, I just want to know what it is.

I mean, its one reading over the course of 24hrs and you want to quit?

Yes. Well it's not just that it's one reading, it's that it's a reading that hasn't been observed in almost a month. Like I said, I HATE eating like this, especially while I'm stuck in the US. It makes me miserable and so I hope to be able to get to a maintenance diet as soon as possible. Seeing negative progress after 3 entire weeks of suffering is definitely enough to make me lose interest.

If that trend continues then an adjustment needs to be made, but shit happens, there could be a number of reason why.

What would I need to look at? Macro adjustments? Quantity (please god no)? Could my workouts be too weak? Too intense? Should I start doing cardio (again, raising my calorie intake beyond what I'm doing would be very very demotivating)?