Fat grafting is more commonly used than ever in plastic surgery, and I use it regularly to enhance results for breast reconstruction patients. The problem is that there are too many risks and limitations to make it the best option for cosmetic breast augmentation, especially with the expectation that size will increase by more than a cup.
Two cup sizes is unrealistic from one procedure since a lot of the fat won’t survive liposuction and processing, and some of it won’t establish new blood flow once injected. Most patients are happy right after surgery but are disappointed 6-12 months later. Even the best fat grafting surgeons in the country are only able to get around a cup size for most patients in the long run.
About 50% of fat is reabsorbed by the body or walled off to form scar tissue or cysts. This can lead to calcium deposits which are visible on mammogram and can be confused with breast cancer. Most radiologists are usually pretty good at telling the difference between the two, but there may be no way other than biopsy to make sure a it doesn’t represent breast cancer.
Finally, although nearly every woman says “I have plenty of fat”, many women simply don’t have enough fat to create the breast size they want. Aggressive lipo can’t be performed (nor can laser or ultrasound lipo) since any damage to fat cells and any blood in the lipoaspirate can affect survival rates.
If you are really set on fat grafting, I recommend going to someone who specializes in this for cosmetic patients and is involved in clinical trials, and ask to see plenty of before and after pictures.