Fat Cells, Hunger, and Heart Disease

Scientists previously thought that fat cells were relatively passive and inert. Now they have evidence that fat cells are metabolically active, continuously communicating with the brain and other organs through at least 25 hormones and other signaling chemicals.

For example, fat cells seem to release hormones that inform the brain how much energy is left and when to stop or start eating, guide muscles in deciding when to burn fat, and tell the liver when to replensis its fat stores.

All this cross talk can be a mixed blessing in the body, however. A healthy population of fat cells, for expample, helps the immune system fight off infection by releasing chemials that cause mild inflammation. But an overactive group of fat cells might keep the inflammation permanently in the "on" position, eventually leading to heart disease.

Sometimes the whole communication system takes on a life of it own. Researchers at the University of western Ontario working with mice found that fat cells in the belly are particularly adept at producing a hormone that not only stimulates appetite, but also spurs nearby immature cells to become full-fledged fat cells.

The results suggest a vicious cycle: Fat cells in the belly cause a person to be hungry and eat more, thus producing more fat cells- leading to even more hunger and even more fat cells.