Sydney: A hormone like leptin could hold the key to why and how people pile on pounds.
Our bodies secrete leptin in response to increasing fat deposits, said Tony Tiganis, professor in biochemistry at the Monash University`s Obesity and Diabetes Institute.
"Leptin instructs the body to increase energy expenditure and decrease food intake, and so helps us maintain a healthy body weight," said Tiganis, who led the study.
"The body`s response to leptin is diminished in overweight and obese individuals, giving rise to the concept of `leptin-resistance`," said Tiganis, the journal Cell Metabolism reports.
Two proteins are already known to inhibit leptin in the brain. Tiganis` team have discovered a third, according to a Monash statement.
In mice, this third protein becomes more abundant with weight-gain, exacerbating leptin-resistance and hastening progression to morbid obesity.
The study showed that these three proteins that regulate leptin take effect at different stages, shedding light on how obesity progresses.
High fat diet-induced weight gain is largely prevented in engineered mice when two of these proteins are deleted in the brain, the study suggested.
"We now have to determine what happens when all three negative regulators are neutralised. Do we prevent high fat diet-induced obesity?
"Humans have a deep-seated attraction to overeating and nutrient-rich food, inherited from our hunter-gatherer ancestors. Now that food is more readily available and our lifestyles are less active, our evolutionary drive to overeat is becoming problematic," said Tiganis.