Hi i'm 19.140 pd 5'5 ft tall and i want to have a brazilian buttlift i wanted to know should i gain a extra 15pds just for the procedure ?

No: Further weight gain may cause other problems check with the doctor who will do the procedure.

Brazilian Butt Lift: I have performed the brazilian butt lift procedure on women weighing 120 pound and 5' 5" tall, so you are not too thin! at 140 pounds you should have enough fat available for redistribution to your buttocks. In fact, the body frame you describe is typical of many of my patients.

Depends: On what expected size you desire. Most patients can have satisfying results with the fat content one would expect you to have with your current weight, and height