Where does the fat that does not survive after a fat grafting procedure go?

During a fat grafting procedure some cells will simply die and not be viable. The body will then break down the cells and fat into metabolite products. The non viable cells can also turn into scar tissue will act as a volume enhancer as well.

Fat grafting is plastic surgery that transfers fat from one area of the body (abdomen, hips, legs) to another (face, breast, buttocks). Unfortunately, not all the fat survives after being re-injected. The fat that does not live ends up being broken down by the body.

Dr. Chaboki

 

Fat that does not survive the injection process releases its free fatty acid content which is picked up and transported the liver where it is broken down and excreted. Some residual non-viable fat may also serve as a stimulus for scar formation. In short, it does not return from whence it came. 

Fat, also known as adipose tissue, is stored in fat cells, adipocytes. These cells are viable, limited in number and are sensitive to physical stressors, such as heat. When fat is transferred from one place to the other, some of the cells do not make it or go into "shock". When those cells die, the body degrades them into inert materials or disposed of.