she reveals in a new interview with Attitude.
“I was smoking 15 joints a day,” admits the singer. “It was a habit that eventually occurred when the pain got so bad with the hip.”
Gaga explains, “I was just numbing, numbing, numbing myself and then sleeping it off and then getting on stage, killing it in pain, then getting off and smoking, smoking, smoking, not knowing what the pain was.”
She says that her experience with performance artist Marina Abramovic helped her kick the habit.

source:http://teewodavie..com/2013/11/i-smoke-15-joints-day-lady-gaga.html

Is she sure she has kicked the habit? Didn't think so.