Just so she can be stuck in a plateau like you are now?
Why is YOUR advice better than mine? What scientific reasoning do you have to back yours up, don't just say it's fact, show me research? I plateaued once like you... once. Because I was being stupid by going too low. But, again, you should really research what your are talking about before you talk about what the body does and how it "burns" fat to compensate, actually you should research it before you try spouting off shitty advice.
A safe deficit should be about 500 calories a day (that's a lb a week), anything more, your getting into more complex body mechanisms that you just don't know anything about, obviously. That deficit should come from a combination of physical activity and calorie reduction for optimum health benefits.