Why don't fat transfers stick in breasts?

You’re taking the words right out of my mouth.  Plastic surgeons promote fat transfer to the breast as a highly successful procedure.  If that’s the case, why so few photos on their websites.  Fat transfers simply do not take well anywhere on the body.  To survive the cells need to obtain a good blood supply which they simply do not when injected in the breasts.  Patients are buying into the hope that fat transfer to the breasts works and plastic surgeons are more than happy to perform it.  If any surgeon recommends fat transfer to you go their website and look at their photos and make sure the photos are at least one year out.  Then bearing in mind these are probably the surgeons best results, judge yourself if that change is worthwhile.

Fat transfers are effective to the chest and approximately 60% survives.  It is good for small volume but large volumes usually will not survive.  The amount of fat capable of survival is proportionate to the recipient site volume.  Unfortunately, you have not provided photographs or told us your bra size.  I would need more information to give you more details.    Best Wishes,Gary Horndeski, M.D.

In general, 200 cc per breast is typically the upper limit of fat injection recommended by most plastic surgeons.  It is not that more cannot be injected; but on average, this has been determined to be the most that can be expected to live during one transfer.  Multiple transfers would be required for additional cc's.  In general, the abdomen and thighs are preferred donor sites but fat from other areas can be used.
Some of the retention rate will depend upon the amount of fat transferred, as smaller volumes will likely have a higher survival.  Occasionally, a patient can resorb a great deal of the fat despite optimal transfer procedures. I typically transfer from 250 cc to 400 cc or so per breast.  Thinner patients are outstanding candidates in my opinion, because the fat transferred is extremely resistant.  
Results are largely dependent upon the skill of the surgeon, his/her ability to remove fat without creating contour deformities, and your expectations. You would need a consultation with a board certified PS to determine your available fat stores.