“An ideal substance would be readily available, inexpensive, long-lasting, natural-feeling, and would not cause adverse immunologic reactions,” writes Dr. Thomas J. Gampper, vice chairman of the Department of Plastic Surgery at University of Virginia School of Medicine. Fat, he concludes, has the potential to hit all of those marks, though, for the moment at least, it’s not necessarily a less expensive option because of the labor involved in removing it, processing it, and injecting it back into the body.