Weight-loss Power of Leptin

The instructions for the body to make leptin are found in the obese (ob) gene. Scientists cloned the ob gene in mice in 1994 and reported in July
1995 that it makes leptin, which is produced only in fat and then is released into the bloodstream. Leptin’s signaling ability may also help explain the high rates of regaining weight found among dieters, says Jeffrey Friedman, M.D., Ph.D., professor at The Rockefeller University and an associate investigator with the Howard Hughes Medical Institute. “After dieting, the levels of leptin drop, suggesting that less leptin is made and available to signal the brain,” Friedman says. “This reduction may contribute to increased hunger and slower metabolism.” Purdue University Professor Ki- Han Kim is in the forefront of research on leptin. Kim, of Purdue’s Department of Biochemistry, says that when his team injected laboratory mice with leptin, previously obese mice became as thin as rodent track stars. “It’s true that the animal isn’t eating as much when it is given leptin,” Kim says. “But that doesn’t mean that the brain is initiating this.

Whenever we eat, we alter the hormonal status of the body. The body has to tell its various parts to do something with this food that has been
ingested. When leptin inhibits fat synthesis, it causes the body to have extra food in its system, which causes the hormonal system to send a message
back to the brain saying that the body is satiated and to stop eating. Recently, the taste organ was also found to be one of the peripheral targets
for leptin. The hormone specifically inhibits sweet taste responses in lean mice. Thus, leptin appears to act as a modulator of sweet taste.
“So leptin’s interaction in the brain isn’t the whole story,” says the Purdue researcher. “Leptin also appears to act via pathways that
are independent of the brain.