Does Fat Transfer to Breasts really work? How long does it last?

Breast fat transfers (lipoaugmentation is what I like to call it) can give you the most natural looking and most natural feeling results possible in the right hands and for the right patient.  The short answer to your question is that nothing lasts forever especially living tissue, and fat is living tissue which is also the best thing about fat transfers.  If it survives the initial transfer process (which you won't know until about 2- 3 months later), it will act like fat where you took it from.  It will enlarge and plump up when you gain weight and shrink when you lose weight (and plump up again when you gain weight).  As you get older (much older) (and like the rest of the tissues of your body) it will slowly whither away (which is one of the reasons why your face gets more gaunt and hollowed out (and why your natural breasts shrink as you get much older)).  The younger you are when you do your fat transfers, the more robust and hardy your fat is, and the more likely a greater percentage of it will survive.  Here is the other thing to remember though- breast implants don't last forever either, and you are looking at several surgeries at a minimum to deal with certain issues as they age such as rupture, capsular contracture, rippling/ wrinkling, implant migration and just routine preventive maintenance replacement should you decide to have silicone gel implants.  These are things you don't have to worry about with lipoaugmentation.
Having said that though, there is no procedure that is ideal for everyone. Every procedure has advantages and disadvantages. The best procedure in the wrong hands or selected for the wrong patient will always result in unhappy patients. There are limitations in what fat transfers can do such as the maximum volume that can be achieved per transfer session (usually not more than one cup size). Unless you are willing to maybe have to do more than one session to achieve more than one cup size, then the procedure is not for you. Also it may cause some lumpiness (but so can implants) but in more experienced hands and for patients who are better candidates, there is less chance of this. Not all surgeons have the same type of experience or have the same hands or use the same techniques so choosing the right surgeon who knows not only how to safely perform the procedure but who also knows how to select the proper patient is very important. Being a good candidate is also important. If you have more good quality fat to give, if you have more breast tissue to begin with and if your breast skin is not too tight, then you would be a better candidate. Also having the right expectations is key. If you are wanting to be 2 cup sizes bigger and are not open to having to possibly do more than one fat transfer session, then you should give serious consideration for breast implants. If you choose fat transfers to the breasts in place of implants, you would be able to avoid inherent risks of implants such as rupture, capsular contracture, rippling, wrinkling and migration of implants.
Getting a consultation from some reputable board certified plastic surgeons who have a lot of experience doing this is a good place to start to see if this is a good option for you.

Fat transfer to the breasts can be an effective form of breast augmentation for up to one cup size increase.Kenneth Hughes, MDLos Angeles, CA

A fat transfer to your breasts is an alternative to undergoing a traditional breast augmentation with implants. Generally, the procedure can increase your cup size some if you have enough donor fat to harvest from other areas of your body. I have had excellent results with  purified fat transfer to the breast but managing expectations with the patient is key. I recommend an in person consult with a board certified plastic surgeon to address a cosmetic treatment plan that best suits your needs.