Imagine if one could drop in at a laser light booth and come out svelte and blemish-free! Don’t count on doing it before your next high school reunion, but studies are already in the works using a free-electron laser to explore how light can target fat cells. Researchers at Massachusetts General Hospital and at Harvard Medical School, both in Boston, and at the US Department of Energy’s Jefferson Lab in Newport News, Va., have shown that a laser can heat fatty tissue without damaging the skin covering it. Relying on the precise tuning of the free-electron laser, they found that light at 915, 1210 and 1720 nm heated lipid-rich tissue nearly twice as efficiently as water. They exposed pig fat samples for about 16 seconds and discovered that, at 1210 nm, the laser-induced heating of fat was more than twice that of the skin. The researchers, who reported their work at the 26th annual meeting of the American Society for Laser Medicine and Surgery in Boston in April, believe that this shows proof of principle for the use of selective photothermolysis, or light-based heat treatments, for a variety of medical applications involving fatty deposits. They envision the development of a “fat-seeking laser” to target the sebaceous glands underlying acne, to reduce the plaques that contribute to atherosclerosis and, yes, perhaps even to help dissolve the unsightly pudge known as cellulite.