Dear Gaby, The reasons for your perceived loss of butt volume 8 years after your butt implants surgery , can be different: 1. Weight loss can affect the butt projection and size.2. Capsule contracture can shrink the butt size if the implants are silicone gel or saline, even if the implants are intact. It does not happen with semi solid ultra soft implants that are used most commonly in the US.3. Saline implants (I operated on a Canadian who had this type of implants ?! ) can break due to intense activity , like sex and the fluid gets absorbed. I consider these implants as well as the silicone gel implants inappropriate for butt implants surgery, because they do not maintain form and can break. You do not have to change the implants per se, unless you want bigger implants , or, you developed asymmetry due to implant's rapture. In any event, to assess your situation, consult with experienced board certified plastic surgeons who operate in accredited surgery center for your safety. Most importantly, check the before and after pictures in the photo gallery, to make sure that they are numerous, consistent and attractive with nice 'S' curve, nice projection, round hips, single hidden scar and natural look. As far as fat injection to the butt, it will be a total waste of your time and your money, since the fat disappears completely , or almost completely within months or even sooner. I have seen it on many patients who came to my surgery center for butt implants surgery, after their big and costly disappointment from the fat injection procedure that was done by other surgeons (I never performed fat injection to the butt) . Think about it this way, Gaby. If fat injection would have been consistent and reliable, most women would have preferred it for breasts augmentation over breasts implants. The reality is, though, that the number one cosmetic surgery in the US is breasts augmentation with implants... So, use your common sense and make your own judgment, regardless of what other doctors tell you. Best of luck, Dr Widder