This is one of the most loaded questions in regards to flexible dieting. It feels as though new research comes out constantly pertaining to this. Yet, we had an article written which outlines how much protein is enough while in a calorie deficit.
We base it on lean body mass rather than body weight which is the amount of weight carried on your body that isn’t fat.
With this said, the reason most go off of body weight is that figuring out your LBM can be difficult. This is why the common recommendation is .7-1 gram/lb. of bodyweight/day.
While in a calorie deficit this is the most straightforward answer, but it may take some trial-and-error.