Injecting only your own fat would be ideal, but some of the fat will be reabsorbed by your body during recovery, so relying completely on your own fat gives less guarantee for a specific size of the breast.
Also injecting a large amount of fat into your breasts has increased the risk of developing oil cysts.
If a moderate to larger size increase is required then the safest way to achieve this is to use a silicone implant combined with fat used to enhance the cleavage and to provide additional cover below and to the side of the implant.

