I have done a lot of buttock augmentations over the past 5 years, and like a lot of people, I thought I would end up doing a balance of fat and implants. This has not been the case. Thin patients, on whom you would think implants would be ideal, are in fact, not that easy to deal with. The implants can be palpable at the outer edges. Secondly, because of anatomic constraints, the implants can't go down as far as you would like, or it can cause nerve compression. I have had to do implant revisions for both palpable edges (used fat injections to increase soft tissue at the edge), and pain from nerve compression. Finally, the implant can't give the volume augmentation you want, because the larger the implant, the more noticeable it is. A "fake" appearance of a buttock implant is not troublesome by itself, it's just that it causes problems when you sit, especially if you are thin. I have done a few skinny patients with fat injections, telling them to focus instead on the change in body contour, and that when the fat grafts take, the weight gain will be predominantly in the buttocks. One patient in particular has gained a lot of weight, and now wants a lipo to the upper pole of the buttocks to reduce the size of the "shelf" I had created. As far as to how long fat lasts, when done correctly, a large percentage of the fat grafted is permanent.