Hello Jessi_howey, It’s a pleasure to answer your questions! Fortunately, a patient’s body would not reject his/her own transferred fat cells. One of the many advantages of Brazilian Butt Lift (BBL) surgery is that it utilizes autologous fat (from the own patient’s body) so the chance of allergic reactions to foreign substances, such as dermal fillers and silicone prosthesis (implants) are significantly reduced, and the final results are longer lasting and more natural looking. Recovery is also better with butt augmentation with autologous fat grafting. BBL’s patients are less prone to suffer post-operative complications and they can typically return to work and their regular activities as soon as one week after surgery. Bear in mind that sitting on the buttocks too soon and for too long after the butt enhancement will result in volume loss due to the resorption of the newly transplanted fat cells. Kind regards! Dr. de La Cruz.