CALORIE / ENERGY BALANCE does dictate the rate of loss so yes there does need to be some control / plan around what we are eating when body fat loss is the goal.
Weather it is mostly FAT or just simply a number on the scales dropping is determined by the approach taken to achieve the result.
Maintaining current lean muscle mass while cutting is the main focus & mindset to be in rather than just trying to lose weight.
If the number on the scales is the main focus lean muscle tissue often makes up a big percentage of the “weight” being lost, this is not a good thing long term.