Treatment with leptin, a natural hormone that helps control body weight, could help many overweight people slim down. Discovered in 1994, leptin is normally produced by fat cells and is believed to provide a signal about the amount of body fat to the body's energy-regulation system.
Leptin treatment has already helped people who completely lack the hormone because of a genetic mutation. But only a handful of people don't have any leptin at all naturally. Results of treatment with other obese people have been disappointing, with only some subjects losing small amounts of weight.
The work suggests that leptin treatment can help not only those very rare overweight people who completely lack the hormone, but also those with low levels. There may be some unknown problems with their leptin genes or their body's ability to produce leptin. Individuals with such problems might be predisposed to become obese and might benefit from leptin therapy.