A study led by Joslin Diabetes Center researchers and published in the Jan. 24, 2003 issue of the journal Science brings scientists one step closer to turning the dream of an estimated 60 million overweight American adults into a reality. The study, conducted in laboratory animals, raises the possibility that new drugs can be developed to make fat cells in the body less sensitive to insulin. Perhaps one day humans, like the genetically altered mice studied, may be able to eat whatever they want and still stay slim — and live longer. The researchers, headed by C. Ronald Kahn at the Joslin Diabetes Center, reported on their experiments with mice that have been genetically altered to have no insulin receptor in fat. These FIRKO mice were able to eat all they wanted and remain lean. In fact, even when they were stimulated to overeat, they failed to gain any extra weight. Matthias Bluher of Joslin and Barbara B. Kahn of Boston’s Beth Israel Deaconess Medical Center’s Department of Medicine also participated in the study. Both institutions are affiliated with Harvard Medical School, where C. Ronald Kahn is the Mary K. Iacocca Professor of Medicine and Barbara Kahn is professor of medicine.