Fat transfer is a relatively comfortable procedure. During the procedure, the most sensitive part is when the local anesthesia or 'numbing' medication is placed. This only takes a minute or two and once placed, the procedure is essentially painless. You will fell a weird pressure sensation from wherever the fat is harvested (usually your abdomen area). Post operatively, my patients end up taking just tylenol 90% of the time. They complain of mild 'pinching sensations' at the harvest site for a few days afterwards. Risks of the procedure vary and are not very common, and can include bleeding, infection, mild unevenness. Your surgeon will discuss with you the complete list. Be reassured that when done correctly and in experienced hands, the risks are significantly lower.