LONDON (Reuters) - U.S. researchers said on Wednesday they had discovered clues about how leptin, the appetite-suppresser protein that regulates weight and metabolism in humans, works. Scientists at the Albert Einstein College of Medicine in New York have identified the biochemical pathway — the way fat cells that produce leptin detect an increase in fat and carbohydrate intake after a meal. The leptin protein, which is regulated by the so-called obese (ob) gene, was discovered in 1994. Obese people have been found to have excess levels of leptin, which scientists believe indicates their body is not reacting to leptin signals. In a report, Rossetti and his colleagues described how their research on rats helped them link leptin to the nutrient-sensing pathway.

Leptin is regulated in two different ways. When a person‘s fat mass increases the body produces more leptin, which tends to decrease the accumulation of more fat by reducing appetite. There is also a rise in leptin about five or six hours after a meal which the researchers believe could be very important in controlling weight and reducing obesity. Rossetti and his team demonstrated that leptin, which is produced by fat cells and the placenta in pregnant women, is also induced in skeletal muscle, which may help to explain how it regulates energy and metabolism. The research could have important implications for diabetics.