Abdominal fat increases the risk of conditions such as heart disease
The fat that some people carry around their middles could be making them even fatter, researchers have said.
The Canadian team found abdominal fat tissue produces a hormone called NPY - which also prompts the development of cells that turn into fat.
It is already known that high levels of the hormone in the brain produce constant feelings of hunger.
A UK expert said better understanding of how the hormone worked might lead to drugs to stop its effects.
Being overweight is bad for health, no matter where the weight lies - but abdominal fat is known to be the most dangerous, increasing the risk of heart disease, Type 2 diabetes, high blood pressure and some cancers.
The researchers, from Lawson Health Research Institute which is linked to the University of Western Ontario, carried out tests on rats which showed abdominal fat, as well as the brain, produces NPY - or Neuropeptide Y.
It is thought the excessive production of NPY in the brain is one of the main reasons why overweight people eat more food.
But the scientists found NPY in abdominal tissues increases fat cell number by stimulating the replication of fat cell precursor cells - which then change into fat cells.
Their findings were published in the Federation of American Societies of Experimental Biology journal.
Dr Kaiping Yang, who led the research, said: "This may lead to a vicious cycle where NPY produced in the brain causes you to eat more and therefore gain more fat around your middle - and then that fat produces more NYP hormone which leads to even more fat cells."
The team will now look at whether NPY produced in the abdomen is released into the body's circulatory system, and therefore affecting hunger messages in the brain.
If it is, it may be possible to develop a simple blood test to detect increased levels of NPY they say.
Dr Yang added: "If you can detect NPY early and identify those at risk for abdominal obesity we can then target therapy to turn off NPY.
"It would be much easier to use drugs to prevent obesity than to treat the diseases caused by obesity."
Dr David Haslam, clinical director of the National Obesity Forum, said the study provided more information on the "complex mechanisms" which regulate how the body stores and processes fat.
He added: "This is one of those findings that, in the not too distant future, might lead to a way of manipulating this hormone's feedback loop.
"It's not science fiction to think you could find some way to block it."