Leptin leapt into the headlines when it was identified in 1995
as a protein that triggers weight loss in mice. But the
appetite-taming hormone lost some luster as the ultimate diet
drug when scientists found last year that obese people already
have high levels of leptin in their blood. This finding
suggested that overweight people may become unable to respond to
leptin, though little is known about leptin's interactions in
the body. Now investigators at Washington University School of
Medicine in St. Louis have identified the first factor to
significantly boost human leptin concentrations. And
surprisingly, this substance also boosted leptin levels in some
overweight individuals. In the study conducted by
endocrinologist Samuel Dagogo-Jack, M.D., assistant professor of
medicine, and by John W. Newcomer, M.D., assistant professor of
psychiatry and of psychology, oral administration of a steroid
hormone for four days doubled the amount of circulating leptin
in 52 patients. Levels of leptin, a product of fat cel