There is a limited space in the breast for the fat transferred to develop an adequate blood supply. Fat which does not survive can disappear or cause hardening. If large volume breast enhancement is desired, you may need a couple of sessions of fat grafting usually spaced 3 to 6 months apart. You should expect about 50-70% of the fat transferred to remain, with the final result seen at 3 months after the procedure and lasting a lifetime. The fat injected into your breasts would fluctuate with your weight.