The idea that fat can be moved from one part of our body where it can be spared to another where it can fill, inflate and rejuvenate is very seductive. But, as with all apparently simple ideas, it is not that simple. The reason why breasts are droopy is multi causal. The unifying reasons are that the RATIO of breast SKIN to breast FILL (gland and fat) has increased. With more a larger stretched skin envelope, EVEN IF the "old" fill (breast tissue and fat were unchanged, the breasts will sag much like a wind sock at the airport or a sail boat when the winds die down. Other factors include loss of support by the cables holding the breast anchored to the chest wall (Cooper's Ligaments) which have been stretched or torn. To correct it our choices are to either REALLY fill the skin envelope (ie VERY large implants or, filler -- a poor choice) OR reduce the size of the envelope with a breast lift (Mastopexy) with or without a breast implant. The trouble with fat grafts to the breasts is that when large portions of the transferred fat does not make it and die, the resulting scar tissue in the breast MAY make it confusing to SOME radiologists reading mammograms to differentiate it from scarring caused by some breast disease including cancer. Moreover, dead fat can be lumpy and hard and drain for months. For this reason most Plastic surgeons approach breast fat grafts with great trepidation. It has become more accepted in breast reconstruction, where the original breast was removed for cancer and the fat is added to a Plastic surgeon-built breast, where it is unlikely to mask or misrepresent a breast cancer. BUT, few of us are comfortable transferring large amounts of fat into a normal breast for the reasons above. I would suggest you see a board certified Plastic surgeon to aid you in your decision making. Good Luck.